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Sample records for resistant laboratory strain

  1. Genetic and biochemical analysis of a laboratory-selected spirodiclofen-resistant strain of Tetranychus urticae Koch (Acari: Tetranychidae).

    Science.gov (United States)

    Van Pottelberge, Steven; Van Leeuwen, Thomas; Khajehali, Jahangir; Tirry, Luc

    2009-04-01

    Spirodiclofen is a selective, non-systemic acaricide from the new chemical class of tetronic acid derivatives. In order to develop strategies to minimise resistance in the field, a laboratory-selected spirodiclofen-resistant strain of the two-spotted spider mite, Tetranychus urticae Koch, was used to determine genetic, toxicological, biochemical and cross-resistance data. Selecting for spirodiclofen resistance in the laboratory yielded a strain (SR-VP) with a resistance ratio of 274, determined on the larval stage. The egg stage remained far more susceptible. No cross-resistance was found against other established acaricides, except for spiromesifen. Based on synergist experiments and enzyme assays, it appeared that especially P450 monooxygenases, but also esterases and glutathione-S-transferases, could be involved in the metabolic detoxification of spirodiclofen. Genetic analysis showed that the resistance is inherited as an intermediate trait under control of more than one gene. Resistance to spirodiclofen exceeded by far the recommended field rate. A good acaricide resistance management programme is necessary to prevent fast resistance build-up in the field. Spirodiclofen can be used in alternation with most established acaricides, except for other tetronic acid derivatives. Without selection pressure, resistance tends to be unstable and can decrease in the presence of susceptible individuals owing to the intermediate, polygenic inheritance mode. Copyright (c) 2009 Society of Chemical Industry.

  2. Molecular characterization, fitness and mycotoxin production of Fusarium graminearum laboratory strains resistant to benzimidazoles.

    Science.gov (United States)

    Sevastos, A; Markoglou, A; Labrou, N E; Flouri, F; Malandrakis, A

    2016-03-01

    Six benzimidazole (BMZ)-resistant Fusarium graminearum strains were obtained after UV mutagenesis and selection on carbendazim (MBC)-amended medium. In vitro bioassays resulted in the identification of two resistant phenotypes that were highly HR (Rf: 40-170, based on EC50) and moderately MR (Rf: 10-20) resistant to carbendazim. Cross resistance studies with other fungicides showed that all mutant strains tested were also resistant to other BMZs, such as benomyl and thiabendazole, but retained their parental sensitivity to fungicides belonging to other chemical groups. A point mutation at codon 6 (His6Asn) was found in the β2-tubulin gene of MR isolates while another mutation at codon 200 (Phe200Tyr) was present in one MR and one HR isolates. Interestingly, low temperatures suppressed MBC-resistance in all isolates bearing the H6N mutation. The three-dimensional homology model of the wild-type and mutants of β-tubulins were constructed, and the possible carbendazim binding site was analyzed. Studies on fitness parameters showed that the mutation(s) for resistance to BMZs did not affect the mycelial growth rate whereas adverse effects were found in sporulation and conidial germination in most of the resistant mutants. Pathogenicity tests on corn cobs revealed that mutants were less or equally aggressive to the wild-type strain but expressed their BMZ-resistance after inoculation on maize cobs treated with MBC. Analysis of mycotoxin production by high performance liquid chromatography revealed that only two HR strains produced zearalenone (ZEA) at concentrations similar to that of the wild-type strain, while no ZEA levels were detected in the rest of the mutants. Copyright © 2015 Elsevier Inc. All rights reserved.

  3. Laboratory and field evaluation of entomopathogenic fungi for the control of amitraz-resistant and susceptible strains of Rhipicephalus decoloratus.

    Science.gov (United States)

    Murigu, Mercy M; Nana, Paulin; Waruiru, Robert M; Nga'nga', Chege J; Ekesi, Sunday; Maniania, Nguya K

    2016-07-30

    Rhipicephalus decoloratus causes serious economic losses in cattle industry every year in East Africa. Biological control using entomopathogenic fungi is seen as a promising alternative to chemical acaricides being used for their control. The pathogenicity of Metarhizium anisopliae and of Beauveria bassiana isolates was tested in the laboratory against amitraz-resistant and amitraz-susceptible strains of R. decoloratus. Unfed larvae were sprayed with conidial suspensions of 1×10(9) conidia ml(-1). Fungal isolates were pathogenic to R. decoloratus larvae, causing mortality of between 10.0 and 100% and between 12.1 and 100% of amitraz-susceptible and amitraz-resistant strains, respectively. The LT50 values of selected fungal isolates varied between 2.6-4.2days in amitraz-susceptible strain and between 2.8-3.9days in amitraz-resistant strain. The LC50 values varied between 0.4±0.1 and 200.0±60×10(3) conidia ml(-1) and between 0.1±0.1 and 200.0±31.0×10(3) conidia ml(-1) in amitraz-susceptible and amitraz-resistant strains, respectively. Metarhizium anisopliae isolate ICIPE 7 outperformed the other isolates and was selected for compatibility study with amitraz and field trial. ICIPE 7 was compatible with amitraz. In the field, four treatments including control, ICIPE 7 alone, amitraz alone and ICIPE 7/amitraz were applied on cattle. All the treatments significantly reduced the number of ticks on all the sampling dates: day 7 (F3,8=3.917; P=0.0284), day 14 (F3,8=9.090; P=0.0275), day 21 (F3,8=37.971; P=0.0001) and day 28 (F3,8=8.170; P=0.0016) compared to the control. Results of the present study indicate that ICIPE 7 can be used for the management of amitraz-resistant strain of R. decoloratus. Copyright © 2016 The Author(s). Published by Elsevier B.V. All rights reserved.

  4. Growth Rate and Biofilm Formation Ability of Clinical and Laboratory-Evolved Colistin-Resistant Strains of Acinetobacter baumannii

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    Zahra Farshadzadeh

    2018-02-01

    Full Text Available Two different mechanisms of resistance to colistin in Acinetobacter baumannii have been described. The first involves the total loss of lipopolysaccharide (LPS due to mutations in the lpxACD operon, which is involved in the lipid A biosynthesis pathway. The second entails the addition of ethanolamine to the lipid A of the LPS resulting from mutations in the PmrAB two-component system. To evaluate the impact of colistin resistance-associated mutations on antimicrobial resistance and virulence properties, four pairs of clinical and laboratory-evolved colistin-susceptible/colistin-resistant (ColS/ColR A. baumannii isolates were used. Antimicrobial susceptibility, surface motility, in vitro and in vivo biofilm-forming capacity, in vitro and in vivo expression levels of biofilm-associated genes, and in vitro growth rate were analyzed in these strains. Growth rate, in vitro and in vivo biofilm formation ability, as well as expression levels of biofilm-associated gene were reduced in ColR LPS-deficient isolate (the lpxD mutant when compared with its ColS partner, whereas there were not such differences between LPS-modified isolates (the pmrB mutants and their parental isolates. Mutation in lpxD was accompanied by a greater reduction in minimum inhibitory concentrations of azithromycin, vancomycin, and rifampin than mutation in pmrB. Besides, loss of LPS was associated with a significant reduction in surface motility without any change in expression of type IV pili. Collectively, colistin resistance through loss of LPS causes a more considerable cost in biological features such as growth rate, motility, and biofilm formation capacity relative to LPS modification. Therefore, ColR LPS-modified strains are more likely to spread and transmit from one patient to another in hospital settings, which results in more complex treatment and control.

  5. Genetic Basis of Cry1F-Resistance in a Laboratory Selected Asian Corn Borer Strain and Its Cross-Resistance to Other Bacillus thuringiensis Toxins.

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    Yueqin Wang

    Full Text Available The Asian corn borer (ACB, Ostrinia furnacalis (Guenée (Lepidoptera: Crambidae, is the most destructive insect pest of corn in China. Susceptibility to the Cry1F toxin derived from Bacillus thuringiensis has been demonstrated for ACB, suggesting the potential for Cry1F inclusion as part of an insect pest management program. Insects can develop resistance to Cry toxins, which threatens the development and use of Bt formulations and Bt crops in the field. To determine possible resistance mechanisms to Cry1F, a Cry1F-resistant colony of ACB (ACB-FR that exhibited more than 1700-fold resistance was established through selection experiments after 49 generations of selection under laboratory conditions. The ACB-FR strain showed moderate cross-resistance to Cry1Ab and Cry1Ac of 22.8- and 26.9-fold, respectively, marginally cross-resistance to Cry1Ah (3.7-fold, and no cross-resistance to Cry1Ie (0.6-fold. The bioassay responses of progeny from reciprocal F1 crosses to different Cry1 toxin concentrations indicated that the resistance trait to Cry1Ab, Cry1Ac and Cry1F has autosomal inheritance with no maternal effect or sex linked. The effective dominance (h of F1 offspring was calculated at different concentrations of Cry1F, showing that h decreased as concentration of Cry1F increased. Finally, the analysis of actual and expected mortality of the progeny from a backcross (F1 × resistant strain indicated that the inheritance of the resistance to Cry1F in ACB-FR was due to more than one locus. The present study provides an understanding of the genetic basis of Cry1F resistance in ACB-FR and also shows that pyramiding Cry1F with Cry1Ah or Cry1Ie could be used as a strategy to delay the development of ACB resistance to Bt proteins.

  6. Benzoate- and Salicylate-Tolerant Strains of Escherichia coli K-12 Lose Antibiotic Resistance during Laboratory Evolution.

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    Creamer, Kaitlin E; Ditmars, Frederick S; Basting, Preston J; Kunka, Karina S; Hamdallah, Issam N; Bush, Sean P; Scott, Zachary; He, Amanda; Penix, Stephanie R; Gonzales, Alexandra S; Eder, Elizabeth K; Camperchioli, Dominic W; Berndt, Adama; Clark, Michelle W; Rouhier, Kerry A; Slonczewski, Joan L

    2017-01-15

    Escherichia coli K-12 W3110 grows in the presence of membrane-permeant organic acids that can depress cytoplasmic pH and accumulate in the cytoplasm. We conducted experimental evolution by daily diluting cultures in increasing concentrations of benzoic acid (up to 20 mM) buffered at external pH 6.5, a pH at which permeant acids concentrate in the cytoplasm. By 2,000 generations, clones isolated from evolving populations showed increasing tolerance to benzoate but were sensitive to chloramphenicol and tetracycline. Sixteen clones grew to stationary phase in 20 mM benzoate, whereas the ancestral strain W3110 peaked and declined. Similar growth occurred in 10 mM salicylate. Benzoate-evolved strains grew like W3110 in the absence of benzoate, in media buffered at pH 4.8, pH 7.0, or pH 9.0, or in 20 mM acetate or sorbate at pH 6.5. Genomes of 16 strains revealed over 100 mutations, including single-nucleotide polymorphisms (SNPs), large deletions, and insertion knockouts. Most strains acquired deletions in the benzoate-induced multiple antibiotic resistance (Mar) regulon or in associated regulators such as rob and cpxA, as well as the multidrug resistance (MDR) efflux pumps emrA, emrY, and mdtA Strains also lost or downregulated the Gad acid fitness regulon. In 5 mM benzoate or in 2 mM salicylate (2-hydroxybenzoate), most strains showed increased sensitivity to the antibiotics chloramphenicol and tetracycline; some strains were more sensitive than a marA knockout strain. Thus, our benzoate-evolved strains may reveal additional unknown drug resistance components. Benzoate or salicylate selection pressure may cause general loss of MDR genes and regulators. Benzoate is a common food preservative, and salicylate is the primary active metabolite of aspirin. In the gut microbiome, genetic adaptation to salicylate may involve loss or downregulation of inducible multidrug resistance systems. This discovery implies that aspirin therapy may modulate the human gut microbiome to

  7. Mutations in nalC gene in ciprofloxacin resistant strains of Pseudomonas aeruginosa isolated from hospitals and laboratories of Guilan province in 2014-2015 years

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    Fatemeh Hakimi

    2016-10-01

    Full Text Available Abstract Background: Pseudomonas aeruginosa is a major nosocomial pathogen that due to its intrinsic and acquired resistance to a wide spectrum of antibiotics poses a threat in clinical settings. One of the drug resistance mechanisms in P. aeruginosa is mutation in negative regulators of efflux pump systems such as nalC. The aim of this study was investigation of nalC mutations in P. aeruginosa isolates from some Rasht hospitals and Lahijan laboratories. Materials and Methods: In this cross-sectional study, forty-five P. aeruginosa strains was isolated from several Rasht hospitals and Lahijan laboratories between 2013 to 2014 and identified by biochemical tests. The antibiotic resistance and susceptibility of isolates was determined by Kirby Bauer method and microdilution method. Then PCR-sequencing was carried out to assess nalC mutations in ciprofloxacin resistant isolates. Results: In this study, the most P. aeruginosa strains was isolated from urine sample (53%, followed by burned strains (31%. The most resistance was seen to erythromycin (100% and the lowest resistance was seen to ciprofloxacin (~31 %. The highest MIC of ciprofloxacin was determined in some strains >512 μg/ml. Sequencing results showed that 12 ciprofloxacin resistant isolates had one or several missense mutations G71E, S209R and E153Q in nalC gene. Conclusion: Given that mutation was defined in most isolates in this study, it seems that mutation in nalC gene plays an important role in ciprofloxacin resistance of nosocomial P. aeruginosa isolates in Guilan province.

  8. Laboratory selection for spirodiclofen resistance and cross ...

    African Journals Online (AJOL)

    Selection for spirodiclofen resistance was done in the laboratory with a susceptible strain of the citrus red mite, Panonychus citri (McGregor). Successive selections for spirodiclofen resistance through 42 generations resulted in a high level of resistance and the resistance ratio at LC50 was 103 compared with that of the ...

  9. The effect of larval nutritional deprivation on the life history and DDT resistance phenotype in laboratory strains of the malaria vector Anopheles arabiensis

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    Oliver Shüné V

    2013-02-01

    Full Text Available Abstract Background Anopheles arabiensis is a major malaria vector in Africa. It thrives in agricultural areas and has been associated with increased malaria incidence in areas under rice and maize cultivation. This effect may be due to increased adult size and abundance as a consequence of optimal larval nutrition. The aim of this study was to examine the effect of larval nutrition on the life history and expression of insecticide resistance in adults of laboratory reared An. arabiensis. Methods Larvae drawn from an insecticide susceptible An. arabiensis strain (SENN as well as a DDT-resistant strain (SENN-DDT were subjected to three fasting regimes: 1 mg of food per larva offered once per day, once every second day and once every third day. Control cohorts included larvae offered 1 mg food thrice per day. The rate of larval development was compared between matched cohorts from each strain as well as between fasted larvae and their respective controls. The expression of DDT resistance/tolerance in adults was compared between the starved cohorts and their controls by strain. Factors potentially affecting variation in DDT resistance/tolerance were examined including: adult body size (wing length, knock-down resistance (kdr status and levels of detoxification enzyme activity. Results and conclusion Anopheles arabiensis larval development is prolonged by nutrient deprivation and adults that eclose from starved larvae are smaller and less tolerant to DDT intoxication. This effect on DDT tolerance in adults is also associated with reduced detoxification enzyme activity. Conversely, well fed larvae develop comparatively quickly into large, more DDT tolerant (SENN or resistant (SENN-DDT adults. This is important in those instances where cereal farming is associated with increased An. arabiensis transmitted malaria incidence, because large adult females with high teneral reserves and decreased susceptibility to insecticide intoxication may also

  10. Acaricide rotation strategy for managing resistance in the tick Rhipicephalus (Boophilus) microplus (Acarina: Ixodidae): laboratory experiment with a field strain from Costa Rica.

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    Thullner, Friederike; Willadsen, Peter; Kemp, David

    2007-09-01

    During the past two decades, resistance to pyrethroids within the cattle tick genus Boophilus has caused tick control problems in various tropical countries, mainly in Latin America, southern Africa, Australia, and New Caledonia. A Rhipicephalus (Boophilus) microplus (Canestrini) strain from Costa Rica, exhibiting resistance to the pyrethroid deltamethrin but only a very low resistance to organophosphates (OP) was kept under selection pressure for 9 to 11 generations by using deltamethrin or coumaphos (OP), either exclusively or in rotation. The objective of this acaricide rotation was to examine the possibility of delaying or reducing the full emergence of pyrethroid resistance. In the substrain selected with deltamethrin at the LD50 concentration, resistance to deltamethrin was measured after five generations (resistance factor [RF] = 9.2) and very high resistance after 11 generations (RF = 756), compared with the starting field strain from Costa Rica. In the substrain selected with deltamethrin then coumaphos in rotation, resistance to deltamethrin was variable from one generation to the next (RF = 1-4.2), but no high, stable resistance developed. After 10 generations of rotation, the deltamethrin RF was 1.6. In the substrains selected continuously with coumaphos or coumaphos and deltamethrin in rotation, no consistent change in resistance to coumaphos was observed. Rotation of deltamethrin with coumaphos seems to delay the development of strong resistance to deltamethrin in a population that had initially a low level of deltamethrin resistance.

  11. Antimicrobial Resistance of Staphylococcal Strains Isolated from Various Pathological Products

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    Laura-Mihaela SIMON

    2010-12-01

    Full Text Available Background: The optimal choice of antimicrobial therapy is an important problem in hospital environment in which the selection of resistant and virulent strains easy occurs. S. aureus and especially MRSA(methicillin-resistant S. aureus creates difficulties in both treatment and prevention of nosocomial infections. Aim: The purpose of this study is to determine the sensitivity and the resistance to chemotherapy of staphylococci strains isolated from various pathological products. Material and Method: We identified Staphylococccus species after morphological appearance, culture properties, the production of coagulase, hemolisines and the enzyme activity. The susceptibility tests were performed on Mueller-Hinton medium according to CLSI (Clinical and Laboratory Standards Institute. Results: The strains were: MSSA (methicillin-susceptible S. aureus (74%, MRSA (8%, MLS B (macrolides, lincosamides and type B streptogramines resistance (12% and MRSA and MLS B (6%. MRSA strains were more frequently isolated from sputum. MRSA associated with the MLS B strains were more frequently isolated from pus. MLS B strains were more frequently isolated from sputum and throat secretions. All S. aureus strains were susceptible to vancomycin and teicoplanin. Conclusions: All staphylococcal infections require resistance testing before treatment. MLS B shows a high prevalence among strains of S. aureus. The association between MLS B and MRSA remains a major problem in Romania.

  12. Challenges and advances in systems biology analysis of Bacillus spore physiology; molecular differences between an extreme heat resistant spore forming Bacillus subtilis food isolate and a laboratory strain

    NARCIS (Netherlands)

    Brul, Stanley; van Beilen, Johan; Caspers, Martien P M; O'Brien, Andrea; de Koster, Chris; Oomes, Suus; Smelt, Jan; Kort, Remco; Ter Beek, Alex

    Bacterial spore formers are prime organisms of concern in the food industry. Spores from the genus Bacillus are extremely stress resistant, most notably exemplified by high thermotolerance. This sometimes allows surviving spores to germinate and grow out to vegetative cells causing food spoilage and

  13. Challenges and advances in systems biology analysis of Bacillus spore physiology; molecular differences between an extreme heat resistant spore forming Bacillus subtilis food isolate and a laboratory strain

    NARCIS (Netherlands)

    Brul, S.; van Beilen, J.; Caspers, M.; O'Brien, A.; de Koster, C.; Oomes, S.; Smelt, J.; Kort, R.; ter Beek, A.

    2011-01-01

    Bacterial spore formers are prime organisms of concern in the food industry. Spores from the genus Bacillus are extremely stress resistant, most notably exemplified by high thermotolerance. This sometimes allows surviving spores to germinate and grow out to vegetative cells causing food spoilage and

  14. Antimicrobial resistance among Brazilian Corynebacterium diphtheriae strains

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    Gabriela Andrade Pereira

    2008-08-01

    Full Text Available The increasing problems with multidrug resistance in relation to Corynebacterium, including C. diphtheriae, are examples of challenges confronting many countries. For this reason, Brazilian C. diphtheriae strains were evaluated by the E-Test for their susceptibility to nine antibacterial drugs used in therapy. Resistance (MIC < 0.002; 0.38 µg/ml to penicillin G was found in 14.8% of the strains tested. Although erythromycin (MIC90 0.75 µg/ml and azithromycin (MIC90 0.064 µg/ml were active against C. diphtheriae in this study, 4.2% of the strains showed decreased susceptibility (MIC 1.0 µg/ml to erythromycin. Multiple resistance profiles were determined by the disk diffusion method using 31 antibiotics. Most C. diphtheriae strains (95.74% showed resistance to mupirocin, aztreonam, ceftazidime, and/or oxacillin, ampicillin, penicillin, tetracycline, clindamycin, lincomycin, and erythromycin. This study presents the antimicrobial susceptibility profiles of Brazilian C. diphtheriae isolates. The data are of value to practitioners, and suggest that some concern exists regarding the use of penicillin.

  15. "Behaviour changes in Permethrin-resistant strain of Anopheles Stephensi "

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    Vatandoost H

    2000-09-01

    Full Text Available Behaviour studies indicated that the permethrin resistant strin of An. Stephensi was 3-fold resistant to knock-down compared with the susceptible strain. The resistant strain was however 3-fold less irritable to permethrin and less responsive than the susceptible strain to the movement of an aspirator. If reduced irritability and reduced responsiveness to catch are consequences of the changes in the nervous system, then such a form of resistance may be disadvantageous to mosquitoes in natural populations.

  16. Fusidic acid resistance among staphylococci strains isolated from clinical specimens

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    Özcan Deveci

    2012-03-01

    Full Text Available Objectives: The aim of this study was to investigate in vitrosusceptibility of fusidic acid to clinic isolates of staphylococci.Materials and methods: The forty-one coagulase negativestaphylococci (CNS and 18 Staphylococcus aureusstrains isolated from various clinical specimens were includedin this study. Staphylococci isolates were identifiedby conventional methods such as colony morphologyonto medium, gram staining, catalase and coagulasetests. According to “Clinical and Laboratory Standards Institute(CLSI” criteria, antimicrobial susceptibility testingof isolates was performed by Kirby-Bauer’s disk diffusionmethod.Results: The seventy-two percent of the isolated S.aureuswere defined as methicillin sensitive-S.aureus (MSSA,28% of the isolated S.aureus were defined as methicillinresistant-S.aureus (MRSA. The difference among fusidicacid susceptibility rates of MSSA and MRSA strains wasnot statistically significant (p=0.305. The twenty-nine percentof the isolated CNS were defined as methicillin sensitive-CNS (MS-CNS, 71% of the isolated CNS were definedas methicillin resistant-CNS (MR-CNS. There wasno statistically significant difference between MS-CNSand MR-CNS strains for fusidic acid susceptibility rates(p=0.490. But the difference among fusidic acid susceptibilityrates of CNS and S.aureus strains was statisticallysignificant (p<0.001. CNS strains were found more resistancethan S.aureus strains for fusidic acid.Conclusion: In this study, the resistance rates weredetected to increase for fusidic acid along with methicillinresistance. Among CNS isolates, fusidic acid resistancerates were significantly more elevated than that forS.aureus. Fusidic acid remains as an alternative in thetreatment of infections due to staphylococci.

  17. Spread of Botrytis cinerea Strains with Multiple Fungicide Resistance in German Horticulture

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    Rupp, Sabrina; Weber, Roland W. S.; Rieger, Daniel; Detzel, Peter; Hahn, Matthias

    2017-01-01

    Botrytis cinerea is a major plant pathogen, causing gray mold rot in a variety of cultures. Repeated fungicide applications are common but have resulted in the development of fungal populations with resistance to one or more fungicides. In this study, we have monitored fungicide resistance frequencies and the occurrence of multiple resistance in Botrytis isolates from raspberries, strawberries, grapes, stone fruits and ornamental flowers in Germany in 2010 to 2015. High frequencies of resistance to all classes of botryticides was common in all cultures, and isolates with multiple fungicide resistance represented a major part of the populations. A monitoring in a raspberry field over six seasons revealed a continuous increase in resistance frequencies and the emergence of multiresistant Botrytis strains. In a cherry orchard and a vineyard, evidence of the immigration of multiresistant strains from the outside was obtained. Inoculation experiments with fungicide-treated leaves in the laboratory and with strawberry plants cultivated in the greenhouse or outdoors revealed a nearly complete loss of fungicide efficacy against multiresistant strains. B. cinerea field strains carrying multiple resistance mutations against all classes of site-specific fungicides were found to show similar fitness as sensitive field strains under laboratory conditions, based on their vegetative growth, reproduction, stress resistance, virulence and competitiveness in mixed infection experiments. Our data indicate an alarming increase in the occurrence of multiresistance in B. cinerea populations from different cultures, which presents a major threat to the chemical control of gray mold. PMID:28096799

  18. Spread of Botrytis cinerea Strains with Multiple Fungicide Resistance in German Horticulture.

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    Rupp, Sabrina; Weber, Roland W S; Rieger, Daniel; Detzel, Peter; Hahn, Matthias

    2016-01-01

    Botrytis cinerea is a major plant pathogen, causing gray mold rot in a variety of cultures. Repeated fungicide applications are common but have resulted in the development of fungal populations with resistance to one or more fungicides. In this study, we have monitored fungicide resistance frequencies and the occurrence of multiple resistance in Botrytis isolates from raspberries, strawberries, grapes, stone fruits and ornamental flowers in Germany in 2010 to 2015. High frequencies of resistance to all classes of botryticides was common in all cultures, and isolates with multiple fungicide resistance represented a major part of the populations. A monitoring in a raspberry field over six seasons revealed a continuous increase in resistance frequencies and the emergence of multiresistant Botrytis strains. In a cherry orchard and a vineyard, evidence of the immigration of multiresistant strains from the outside was obtained. Inoculation experiments with fungicide-treated leaves in the laboratory and with strawberry plants cultivated in the greenhouse or outdoors revealed a nearly complete loss of fungicide efficacy against multiresistant strains. B. cinerea field strains carrying multiple resistance mutations against all classes of site-specific fungicides were found to show similar fitness as sensitive field strains under laboratory conditions, based on their vegetative growth, reproduction, stress resistance, virulence and competitiveness in mixed infection experiments. Our data indicate an alarming increase in the occurrence of multiresistance in B. cinerea populations from different cultures, which presents a major threat to the chemical control of gray mold.

  19. Antimicrobial Resistance Patterns of Isolated Vibrio cholerae Strains

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    Masood Hajia

    2016-02-01

    Full Text Available Background: Cholera is a potentially life-threatening acute diarrheal disease caused by the toxigenic bacteria, Vibrio cholerae. Antibiotics should be selected using local antibiotic susceptibility testing patterns. Objectives: This study was performed to identify the patterns of antimicrobial resistance in isolates collected from laboratory-confirmed cases of cholera during three years, from 2011 to 2013. Materials and Methods: All isolates at the Health Reference Laboratory were tested by the Minimum Inhibitory Concentration (MIC Test using Liofilchem against ciprofloxacin, nalidixic acid, cefixime, ampicillin, tetracycline, trimethoprim-sulfamethoxazole, and erythromycin. The following organisms were used as quality control strains for MIC E-testing; Escherichia coli (ATCC 25922, Staphylococcus aureus (ATCC 29213, and Pseudomonas aeruginosa (ATCC 27853. Results: Results of susceptibility testing showed complete sensitivity to ciprofloxacin, cefixime and amplicillin for both isolated Inaba and Ogawa serotypes except all isolated Inaba serotypes from year 2011, which were resistant to cefixime. These resistant Inaba serotypes were not isolated in the next year. Inaba serotypes showed an increased resistance rate of up to 100% to nalidixic acid, tetracycline and trimethoprim-sulfamethaxazone, while Ogawa serotypes were 100% sensitive at the end of year 2013. The susceptibility pattern of erytromycine was similar in these two types. Sensitivity to erythromycin was decreased in both Inaba and Ogawa serotypes. Conclusions: The analyzed results indicate that tetracycline should not be considered as a first line antibiotic therapy for patients infected with Ogawa serotypes. Also, national guidelines for confirmation of cholera should be improved by responsible authorities to cover new resistance during outbreaks.

  20. [Antimicrobial resistance of Bartonella bacilliformis strains from regions endemic to bartonellosis in Peru].

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    Mendoza-Mujica, Giovanna; Flores-León, Diana

    2015-10-01

    To evaluate in vitro antimicrobial susceptibility to chloramphenicol (CHL) and ciprofloxacin (CIP) in strains of Bartonella bacilliformis from areas that are endemic to Bartonellosis in Peru, through three laboratory methods. Antimicrobial susceptibility to CHL and CIP from 100 strains of Bartonella bacilliformis isolated in patients from the regions of Ancash, Cusco, Cajamarca, Lima and La Libertad were evaluated. Strains were evaluated by: disk diffusion, E-test and agar dilution. 26% of the strains of Bartonella bacilliformis evaluated were resistant to CIP and 1% to CHL. Similar patterns of antimicrobial sensitivity / resistance were obtained in all three methods. Bartonella bacilliformis strains circulating in Peru have high levels of in vitro resistance to CIP, so it is advisable to expand research on the use of drug treatment regimens of the Bartonellosis. The methods of E-test and disk diffusion were the most suitable for assessment in vitro of antimicrobial susceptibility of the microorganism.

  1. Leading Antibacterial Laboratory Research by Integrating Conventional and Innovative Approaches: The Laboratory Center of the Antibacterial Resistance Leadership Group.

    Science.gov (United States)

    Manca, Claudia; Hill, Carol; Hujer, Andrea M; Patel, Robin; Evans, Scott R; Bonomo, Robert A; Kreiswirth, Barry N

    2017-03-15

    The Antibacterial Resistance Leadership Group (ARLG) Laboratory Center (LC) leads the evaluation, development, and implementation of laboratory-based research by providing scientific leadership and supporting standard/specialized laboratory services. The LC has developed a physical biorepository and a virtual biorepository. The physical biorepository contains bacterial isolates from ARLG-funded studies located in a centralized laboratory and they are available to ARLG investigators. The Web-based virtual biorepository strain catalogue includes well-characterized gram-positive and gram-negative bacterial strains published by ARLG investigators. The LC, in collaboration with the ARLG Leadership and Operations Center, developed procedures for review and approval of strain requests, guidance during the selection process, and for shipping strains from the distributing laboratories to the requesting investigators. ARLG strains and scientific and/or technical guidance have been provided to basic research laboratories and diagnostic companies for research and development, facilitating collaboration between diagnostic companies and the ARLG Master Protocol for Evaluating Multiple Infection Diagnostics (MASTERMIND) initiative for evaluation of multiple diagnostic devices from a single patient sampling event. In addition, the LC has completed several laboratory-based studies designed to help evaluate new rapid molecular diagnostics by developing, testing, and applying a MASTERMIND approach using purified bacterial strains. In collaboration with the ARLG's Statistical and Data Management Center (SDMC), the LC has developed novel analytical strategies that integrate microbiologic and genetic data for improved and accurate identification of antimicrobial resistance. These novel approaches will aid in the design of future ARLG studies and help correlate pathogenic markers with clinical outcomes. The LC's accomplishments are the result of a successful collaboration with the ARLG

  2. Phenotypic and genomic comparisons of highly vancomycin-resistant Staphylococcus aureus strains developed from multiple clinical MRSA strains by in vitro mutagenesis.

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    Ishii, Kenichi; Tabuchi, Fumiaki; Matsuo, Miki; Tatsuno, Keita; Sato, Tomoaki; Okazaki, Mitsuhiro; Hamamoto, Hiroshi; Matsumoto, Yasuhiko; Kaito, Chikara; Aoyagi, Tetsuji; Hiramatsu, Keiichi; Kaku, Mitsuo; Moriya, Kyoji; Sekimizu, Kazuhisa

    2015-11-25

    The development of vancomycin (VCM) resistance in Staphylococcus aureus threatens global health. Studies of the VCM-resistance mechanism and alternative therapeutic strategies are urgently needed. We mutagenized S. aureus laboratory strains and methicillin-resistant S. aureus (MRSA) with ethyl methanesulfonate, and isolated mutants that exhibited high resistance to VCM (minimum inhibitory concentration = 32 μg/ml). These VCM-resistant strains were sensitive to linezolid and rifampicin, and partly to arbekacin and daptomycin. Beta-lactams had synergistic effects with VCM against these mutants. VCM-resistant strains exhibited a 2-fold increase in the cell wall thickness. Several genes were commonly mutated among the highly VCM-resistant mutants. These findings suggest that MRSA has a potential to develop high VCM resistance with cell wall thickening by the accumulation of mutations.

  3. drug resistant strains of Salmonella enterica

    African Journals Online (AJOL)

    Conclusions: The aqueous extract of Thonningia sanguinea can provide an alternative therapy for the treatment of salmonellosis, mainly for typhoid fever caused by MDR strains of S. Typhi.The extract also inhibits S.Hadar a MDR emerging strain in Ivory Coast. Keywords: Thonningia sanguinea; Salmonella, MDR strains, ...

  4. Cytotoxic Escherichia coli strains encoding colibactin colonize 1 laboratory mice

    Science.gov (United States)

    García, Alexis; Mannion, Anthony; Feng, Yan; Madden, Carolyn M.; Bakthavatchalu, Vasudevan; Shen, Zeli; Ge, Zhongming; Fox, James G.

    2016-01-01

    Escherichia coli strains have not been fully characterized in laboratory mice and are not currently excluded from mouse colonies. Colibactin (Clb), a cytotoxin, has been associated with inflammation and cancer in humans and animals. We performed bacterial cultures utilizing rectal swab, fecal, and extra intestinal samples from clinically unaffected or affected laboratory mice. Fifty-one E. coli were isolated from 45 laboratory mice, identified biochemically, and selected isolates were serotyped. The 16S rRNA gene was amplified and sequenced for specific isolates, PCR used for clbA and clbQ gene amplification, and phylogenetic group identification was performed on all 51 E. coli strains. Clb genes were sequenced and selected E. coli isolates were characterized using a HeLa cell cytotoxicity assay. Forty-five of the 51 E. coli isolates (88 %) encoded clbA and clbQ and belonged to phylogenetic group B2. Mouse E. coli serotypes included: O2:H6, O−:H−, OM:H+, and O22:H−. Clb-encoding O2:H6 mouse E. coli isolates were cytotoxic in vitro. A Clb-encoding E. coli was isolated from a clinically affected genetically modified mouse with cystic endometrial hyperplasia. Our findings suggest that Clb-encoding E. coli colonize laboratory mice and may induce clinical and subclinical diseases that may impact experimental mouse models. PMID:27480057

  5. High incidence of multidrug-resistant strains of methicill inresistant ...

    African Journals Online (AJOL)

    Infections of methicillin-resistant Staphylococcus aureus (MRSA) are becoming an increasingly concerning clinical problem. The aim of this study was to assess the development of multidrug resistant strains of MRSA from clinical samples andpossibilities for reducing resistance. This study included a total of seventy-five (75) ...

  6. Relationship between ethanol and oxidative stress in laboratory and brewing yeast strains.

    Science.gov (United States)

    Bleoanca, Iulia; Silva, Ana Rita Courelas; Pimentel, Catarina; Rodrigues-Pousada, Claudina; Menezes, Regina de Andrade

    2013-12-01

    Ethanol is a chemical stress factor that inhibits cellular growth and determines metabolic changes leading to reduction of cell viability during fermentation and yeast storage. To determine the effect of time, temperature and ethanol during storage of brewing yeasts we have monitored viability of cells stored for 72 h, at 6 °C or 12 °C, in the presence of various ethanol concentrations. Under the conditions tested, 6 °C is the most favourable temperature to store brewing yeast creams emphasizing the importance of a tight temperature control in the storage vessels. Because W210 is less resistant to storage in the presence of ethanol than W34/70, the optimal storage parameters obtained under our laboratory conditions vary significantly. The ale strain is sensitive to storage under ethanol concentrations higher than 5% (v/v) for more than 48 h at 6 °C whereas at the same temperature the lager strain tolerates ethanol up to 7.5% (v/v) for 72 h. Also, the viability assays indicate that the antioxidant protein Yap1 is an important factor to storage resistance of BY4741 laboratory strain. To investigate the molecular mechanisms underlying tolerance of brewing yeast strains to ethanol, we have performed phenotypic analysis, localization studies and have monitored the activation of antioxidant and protection genes as well as the intracellular contents of glycogen and trehalose. Overall, our data suggest that the ale strain W210 has a defective antioxidant defence system and that ethanol may induce the antioxidant defences as well as glycogen and trehalose protection mechanisms in laboratory and brewing yeast strains. Copyright © 2013 The Society for Biotechnology, Japan. Published by Elsevier B.V. All rights reserved.

  7. Stability of spinosad resistance in Frankliniella occidentalis (Pergande) under laboratory conditions.

    Science.gov (United States)

    Bielza, P; Quinto, V; Grávalos, C; Fernández, E; Abellán, J; Contreras, J

    2008-08-01

    The stability of spinosad resistance in western flower thrips (WFT), Frankliniella occidentalis (Pergande), populations with differing initial frequencies of resistance was studied in laboratory conditions. The stability of resistance was assessed in bimonthly residual bioassays in five populations with initial frequencies of 100, 75, 50, 25 and 0% of resistant individuals. There were no consistent changes in susceptibility of the susceptible strain after eight months without insecticide pressure. In the resistant strain, very highly resistant to spinosad (RF50>23,000-fold), resistance was maintained up to eight months without further exposure to spinosad. In the absence of any immigration of susceptible genes into the population, resistance was stable. In the case of the population with different initial frequency of resistant thrips, spinosad resistance declined significantly two months later in the absence of selection pressure. With successive generations, these strains did not change significantly in sensitivity. Spinosad resistance in F. occidentalis declined significantly in the absence of selection pressure and the presence of susceptible WFT. These results suggest that spinosad resistance probably is unstable under field conditions, primarily due to the immigration of susceptible WFT. Factors influencing stability or reversion of spinosad resistance are discussed.

  8. A virtual laboratory for neutron and synchrotron strain scanning

    International Nuclear Information System (INIS)

    James, J.A.; Santisteban, J.R.; Edwards, L.; Daymond, M.R.

    2004-01-01

    The new generation of dedicated Engineering Strain Scanners at neutron and synchrotron facilities offer considerable improvements in both counting time and spatial resolution. In order to make full use of these advances in instrumentation, the routine tasks associated with setting up measurement runs and analysing the data need to be made as efficient as possible. Such tasks include the planning of the experiment, the alignment and positioning of the specimen, the least-squares refinement of diffraction spectra, the definition of strain in the sample coordinate system, and its visualization within a 3D model of the specimen. With this aim in mind, we have written a software providing support for most of these operations. The approach is based on a virtual lab consisting of 3D models of the sample and laboratory equipment. The system has been developed for ENGIN-X, the new engineering strain scanner recently commissioned at ISIS, but it is flexible enough to be ported to other neutron or synchrotron strain scanners. The software has been designed with visiting industrial and academic researchers in mind, users who need to be able to control the instrument after only a short period of training

  9. A comparative study of P450 gene expression in field and laboratory Musca domestica L. strains

    DEFF Research Database (Denmark)

    Højland, Dorte Heidi; Vagn Jensen, Karl-Martin; Kristensen, Michael

    2014-01-01

    unselected strains: a multiresistant strain (791a), a neonicotinoid-resistant strain (766b) and a new field strain (845b). RESULTS CYP4G2 was highly expressed throughout the range of strains and proved to be the one of the most interesting expression profiles of all P450s analysed. CYP6G4 was expressed up...... that CYP6G4 is a major insecticide resistance gene involved in neonicotinoid resistance. © 2013 Society of Chemical Industry...

  10. Antibiotic Resistance Determinants in a Pseudomonas putida Strain Isolated from a Hospital

    Science.gov (United States)

    Duque, Estrella; Fernández, Matilde; Molina-Santiago, Carlos; Roca, Amalia; Porcel, Mario; de la Torre, Jesús; Segura, Ana; Plesiat, Patrick; Jeannot, Katy; Ramos, Juan-Luis

    2014-01-01

    Environmental microbes harbor an enormous pool of antibiotic and biocide resistance genes that can impact the resistance profiles of animal and human pathogens via horizontal gene transfer. Pseudomonas putida strains are ubiquitous in soil and water but have been seldom isolated from humans. We have established a collection of P. putida strains isolated from in-patients in different hospitals in France. One of the isolated strains (HB3267) kills insects and is resistant to the majority of the antibiotics used in laboratories and hospitals, including aminoglycosides, ß-lactams, cationic peptides, chromoprotein enediyne antibiotics, dihydrofolate reductase inhibitors, fluoroquinolones and quinolones, glycopeptide antibiotics, macrolides, polyketides and sulfonamides. Similar to other P. putida clinical isolates the strain was sensitive to amikacin. To shed light on the broad pattern of antibiotic resistance, which is rarely found in clinical isolates of this species, the genome of this strain was sequenced and analysed. The study revealed that the determinants of multiple resistance are both chromosomally-borne as well as located on the pPC9 plasmid. Further analysis indicated that pPC9 has recruited antibiotic and biocide resistance genes from environmental microorganisms as well as from opportunistic and true human pathogens. The pPC9 plasmid is not self-transmissible, but can be mobilized by other bacterial plasmids making it capable of spreading antibiotic resistant determinants to new hosts. PMID:24465371

  11. Antimicrobial resistance of bacterial strains isolated from orange ...

    African Journals Online (AJOL)

    The organisms encountered include Saccharomyces cerevisiae, Saccharomyces sp, Rhodotorula sp, Bacillus cereus, Bacillus subtilis, Escherichia coli, Staphylococcus aureus, Streptococcus pyogenes and Micrococcus sp. The resistances of thirty bacterial strains isolated from orange juice products to the commonly used ...

  12. A comparison of stress tolerance in YPD and industrial lignocellulose-based medium among industrial and laboratory yeast strains.

    Science.gov (United States)

    Albers, Eva; Larsson, Christer

    2009-08-01

    In general, it is believed that fermentation by yeast under harsh industrial conditions, especially if substrates such as wood hydrolysate or lignocellulosic substrates are used, requires the use of so-called industrial strains. In order to check whether this is always true, a comparison of performance was made using two industrial strains and four commonly used laboratory strains, the haploid and diploid versions of CEN-PK and X2180, under industrially relevant stress conditions. The industrial strains were a Swedish commercial baker's yeast strain and a strain previously isolated from an industrial bioethanol production plant using lignocellulosic substrate. Stress conditions included, apart from growth in the lignocellulosic substrate itself, elevated concentrations of glucose, NaCl, ethanol, and lactate as well as low pH. Results showed that, indeed, the strain adapted to lignocellulosic substrate also possessed the highest growth rate as well as shortest duration of the lag phase in this type of medium. However, the higher the additional stress level, the lower the difference compared to other strains, and X2180 in particular displayed a high resistance to these additional stress conditions. Furthermore, no difference in performance could be detected between the haploid or diploid versions of the laboratory strains. It might be that, at least under some circumstances, a laboratory strain such as X2180 could be an industrially attractive production organism with the advantage of facilitating the possibilities for making controlled genetic manipulations.

  13. Antibiotic Resistance in Staphylococcus aureus Strains Isolated from Clinical Specimens

    Directory of Open Access Journals (Sweden)

    M. Sirin

    2016-04-01

    Full Text Available Aim: The aim of this study was to determine the antibiotic susceptibilities of S.aureus strains isolated from various clinical specimens between the years 2011-2014 and to investigate the changes of these susceptibilities over the years. Material and Method: Identification and antibiotic susceptibility testing of the strains were performed by Vitek 2 compact automated system (bioMérieux, France. The strains found to be intermediate susceptible to vancomycin and teicoplanin were also tested by E-test method. Results: S.aureus strains (n=1442 were most commonly isolated from wound, urine and blood samples. The isolation rates of methicillin-resistant S.aureus (MRSA in hospitalized patients were significantly higher than the isolation rates of MRSA in outpatients. All strains were susceptible to vancomycin, teicoplanin, linezolid and tigecycline. The total of four years resistance rates of MRSA strains to erythromycin, clindamycin, ciprofloxacin, moxifloxacin, gentamicin, co-trimoxazole, fusidic acid were significantly higher than the resistance rates of methicillin-sensitive S.aureus (MSSA. The changes in the rates of antibiotic resistance were not statistically significant in MSSA strains over the years, and statistically significant decrease was found in erythromycin, clindamycin, ciprofloxacin, moxifloxacin and gentamicin resistance in MRSA strains. Discussion: Glycopeptides, linezolid and tigecycline were the most effective antibiotics against S.aureus strains. It was considered as necessary to detect antimicrobial resistance profiles by effective surveillance studies and monitor the changes occurred over the years in order to prevent the development of resistance and control of infections.

  14. [Resistance of Mycobacterium tuberculosis strains to antimycobacterial preparations].

    Science.gov (United States)

    Iavors'ka, H V; Puhachevs'ka, L P

    2006-01-01

    Investigations of dynamics of Mycobacterium tuberculosis strains, isolated from patients with pulmonary tuberculosis were carried out in the Lviv region during 1994-2003. As a result of conducted investigations the tendency was revealed to increasing the amount of cultures resistant to streptomycine, isoniazide, canamycine, ethambutol, ryfampycine and their multiresistance during the investigation years. High quantity of resistant strains was revealed in common in 1997, 1999 and 2002.

  15. Antimicrobial resistance of non-clinical Escherichia coli strains from ...

    African Journals Online (AJOL)

    This study was carried out to determine resistance profiles of Escherichia coli strains isolated from clinically healthy chickens in Nsukka, southeast Nigeria. A total of 324 E. coli strains isolated from cloaca swabs from 390 chickens were tested against 16 antimicrobial agents using the disc diffusion method. The antibiotics ...

  16. [Current antibiotic resistance profile of uropathogenic Escherichia coli strains and therapeutic consequences].

    Science.gov (United States)

    El Bouamri, M C; Arsalane, L; Kamouni, Y; Yahyaoui, H; Bennouar, N; Berraha, M; Zouhair, S

    2014-12-01

    Urinary tract infections (UTI) are a very common reason for consultation and prescription in current practice. Excessive or inappropriate use of antibiotics in treating urinary tract infections is responsible for the emergence and spread of multiresistant uropathogenic bacteria. To evaluate the isolation frequency and antibiotic resistance of uropathogenic Escherichia coli strains isolated at the Marrakech region. We conducted a retrospective study over a period of three years (from 1st January 2010 to 31 December 2012). It included all non-redundant uropathogenic E. coli strains isolated in the microbiology laboratory of the Avicenne hospital of Marrakech, Morocco. During this study, 1472 uropathogenic enterobacteriaceae were isolated including 924 non-repetitive E. coli strains, an overall isolation frequency of 63%. Antibiotic resistance of isolated E. coli strains showed resistance rates to amoxicillin (65%), sulfamethoxazole-triméthropime (55%), amoxicillin-clavulanic acid (43%), ciprofloxacin (22%), gentamicin (14%), nitrofurans (11%), amikacin (8%) and fosfomycin (7%). The number of E. coli strains resistant to C3G by ESBL production was 67, an average frequency of 4.5% of all isolated uropathogenic enterobacteria. The associated antibiotic resistance in the case of ESBL-producing E. coli were 82% for ciprofloxacin, 76% for sulfamethozole trimethoprim, 66% for gentamicin and 56% for amikacin. No resistance to imipenem was recorded for the isolated E. coli strains, which represents an imipenem sensitivity of 100%. Antibiotic resistance of uropathogenic E. coli strains limits treatment options and therefore constitutes a real public health problem. The regular updating of antibiotic susceptibility statistics of E. coli strains allows a better adaptation of the probabilistic antibiotic therapy to local epidemiological data. Copyright © 2014 Elsevier Masson SAS. All rights reserved.

  17. Transcription profiling of a recently colonised pyrethroid resistant Anopheles gambiae strain from Ghana

    Directory of Open Access Journals (Sweden)

    Donnelly Martin J

    2007-01-01

    Full Text Available Abstract Background Mosquito resistance to the pyrethroid insecticides used to treat bednets threatens the sustainability of malaria control in sub-Saharan Africa. While the impact of target site insensitivity alleles is being widely discussed the implications of insecticide detoxification – though equally important – remains elusive. The successful development of new tools for malaria intervention and management requires a comprehensive understanding of insecticide resistance, including metabolic resistance mechanisms. Although three enzyme families (cytochrome P450s, glutathione S-transferases and carboxylesterases have been widely associated with insecticide detoxification the role of individual enzymes is largely unknown. Results Here, constitutive expression patterns of genes putatively involved in conferring pyrethroid resistance was investigated in a recently colonised pyrethroid resistant Anopheles gambiae strain from Odumasy, Southern Ghana. RNA from the resistant strain and a standard laboratory susceptible strain, of both sexes was extracted, reverse transcribed and labelled with either Cy3- or Cy5-dye. Labelled cDNA was co-hybridised to the detox chip, a custom-made microarray containing over 230 A. gambiae gene fragments predominantly from enzyme families associated with insecticide resistance. After hybridisation, Cy3- and Cy5-signal intensities were measured and compared gene by gene. In both females and males of the resistant strain the cytochrome P450s CYP6Z2 and CYP6M2 are highly over-expressed along with a member of the superoxide dismutase (SOD gene family. Conclusion These genes differ from those found up-regulated in East African strains of pyrethroid resistant A. gambiae and constitute a novel set of candidate genes implicated in insecticide detoxification. These data suggest that metabolic resistance may have multiple origins in A. gambiae, which has strong implications for the management of resistance.

  18. Cross-resistance of bisultap resistant strain of Nilaparvata lugens and its biochemical mechanism.

    Science.gov (United States)

    Ling, Shanfeng; Zhang, Runjie

    2011-02-01

    The resistant (R) strain of the planthopper Nilaparvata lugens (Stål) selected for bisultap resistance displayed 7.7-fold resistance to bisultap and also had cross-resistance to nereistoxin (monosultap, thiocyclam, and cartap), chlorpyrifos, dimethoate, and malathion but no cross-resistance to buprofezin, imidacloprid, and fipronil. To find out the biochemical mechanism of resistance to bisultap, biochemical assay was done. The results showed that cytochrome P450 monooxygenases (P450) activity in R strain was 2.71-fold that in susceptible strain (S strain), in which the changed activity for general esterase (EST) was 1.91 and for glutathione S-transferases only 1.32. Piperonyl butoxide (PBO) could significantly inhibit P450 activity (percentage of inhibition [PI]: 37.31%) in the R strain, with ESTs PI = 16.04% by triphenyl phosphate (TPP). The results also demonstrated that diethyl maleate had no synergism with bisultap. However, PBO displayed significant synergism in three different strains, and the synergism increased with resistance (S strain 1.42, Lab strain, 2.24 and R strain, 3.23). TPP also showed synergism for three strains, especially in R strain (synergistic ratio = 2.47). An in vitro biochemical study and in vivo synergistic study indicated that P450 might be play important role in the biochemical mechanism of bisultap resistance and that esterase might be the important factor of bisultap resistance. Acetylcholinesterase (AChE) insensitivity play important role in bisultap resistance. We suggest that buprofezin, imidacloprid, and fipronil could be used in resistance management programs for N. lugens via alternation and rotation with bisultap.

  19. Antimicrobial resistance of bacterial strains isolated from avian cellulitis

    Directory of Open Access Journals (Sweden)

    MM Santos

    2014-03-01

    Full Text Available Avian cellulitis is an inflammatory process in the subcutaneous tissue, mainly located in the abdomen and thighs. This problem is commonly observed in poultry at slaughter and it is considered one of the major causes of condemnation of carcasses in Brazil. The aim of this study was to perform the microbial isolation of lesions of avian cellulitis from a processing plant located in the State of Goiás in order to analyze antimicrobial resistance by antibiogram test and to detect resistance genes by polymerase chain reaction. A total of 25 samples of avian cellulitis lesions were analyzed, from which 30 bacterial strains were isolated. There were eleven (44% strains of Escherichia coli, nine (36% strains of Staphylococcus epidermidis, seven (28% strains of Proteus mirabilis and three (12% strains of Manheimiahaemolytica. The antibiogram test showed that all strains were resistant to at least one antimicrobial. The gene of antimicrobial resistance tetB was detected in E. coli, S. epidermidis and P. mirabilis strains, and was the most frequently observed gene. The gene of antimicrobial resistance Sul1 was detected in all bacterial species, while tetA was found in E. coli and S. epidermidis strains, SHV in E. coli strains, S. epidermidis and P. mirabilis,and cat1 in one P. mirabilis strain. The results suggest a potential public health hazard due to the ability of these microorganisms to transmit antimicrobial resistancegenes to other microorganisms present in the intestinal tract of humans and animals, which may affect clinical-medical usage of these drugs.

  20. A Survey of Antibiotic Resistant Staphylococcus Aureus Strains from ...

    African Journals Online (AJOL)

    A survey of antibiotic resistant Staphylococcus aureus strains from clinical specimens was carried out. A total of 100 different clinical specimens were investigated with a yield of 48 Staphylococcus aureus isolates. A high resistance of 95.8% to penicillin, 89.6% to ampicillin, 87.5% to tetracycline, and 75.0% to ...

  1. Genome sequences of Listeria monocytogenes strains with resistance to arsenic

    Science.gov (United States)

    Listeria monocytogenes frequently exhibits resistance to arsenic. We report here the draft genome sequences of eight genetically diverse arsenic-resistant L. monocytogenes strains from human listeriosis and food-associated environments. Availability of these genomes would help to elucidate the role ...

  2. Drug resistance analysis of bacterial strains isolated from burn patients.

    Science.gov (United States)

    Wang, L F; Li, J L; Ma, W H; Li, J Y

    2014-01-22

    This study aimed to analyze the spectrum and drug resistance of bacteria isolated from burn patients to provide a reference for rational clinical use of antibiotics. Up to 1914 bacterial strain specimens isolated from burn patients admitted to hospital between 2001 and 2010 were subjected to resistance monitoring by using the K-B paper disk method. Retrospective analysis was performed on drug resistance analysis of burn patients. The top eight bacterium strains according to detection rate. A total of 1355 strains of Gram-negative (G(-)) bacteria and 559 strains of Gram-positive (G(+)) bacteria were detected. The top eight bacterium strains, according to detection rate, were Acinetobacter baumannii, Pseudomonas aeruginosa, Staphylococcus aureus, Escherichia coli, Staphylococcus epidermidis, Klebsiella pneumoniae, Enterobacter cloacae, and Enterococcus. Drug resistance rates were higher than 90% in A. baumannii, P. aeruginosa, S. epidermidis, and S. aureus, which accounted for 52.2, 21.7, 27.8, and 33.3%, respectively, of the entire sample. Those with drug resistance rates lower than 30% accounted for 4.3, 30.4, 16.7, and 16.7%, respectively. Multidrug-resistant S. aureus (MRSA) and methicillin-resistant S. epidermidis (MRSE) accounted for 49.2 and 76.4% of the S. epidermis and S. aureus resistance, respectively. Antibacterial drugs that had drug resistance rates to MRSE and MRSA higher than 90% accounted for 38.9 and 72.2%, respectively, whereas those with lower than 30% drug resistance rates accounted for 11.1 and 16.7%, respectively. The burn patients enrolled in the study were mainly infected with G(-) bacteria. These results strongly suggest that clinicians should practice rational use of antibiotics based on drug susceptibility test results.

  3. Antibiotics resistance of Stenotrophomonas maltophilia strains ...

    African Journals Online (AJOL)

    BD Phoenixautomated microbiology system (Becton Dickinson, USA) was utilized for species level identification and antibiotic susceptibility testing. Results: Sixty seven of S. maltophilia strains were isolated from tracheal aspirate isolates, 17 from blood, 10 from sputum, 10 from wound and 14 from other clinical specimens.

  4. Isolation and identification of a novel radio-resistant strain

    International Nuclear Information System (INIS)

    Zhang Zhidong; Mao Jun; Wang Wei; Tang Qiyong; Shi Yuhu

    2008-01-01

    A novel radio-resistant strain named RL2 was studied polyphasically, which was isolated from the soils in the Gurban-Tunggut Desert, Xinjiang. The strain is Gam-positive, sphere-shaped and pink pigmented; The DNA (G+C) contents of RL2 is 71.62mo1%; The 16S rDNA genes of RL2 and D. radiodurans type strain DSM20539 shows a high level of similarity (97.2%). According to phenotypic characteristics and phylogenetic analysis, it can be suggested that the strain RL2 has been identified as Deinococcus. sp and it may be a novel species. (authors)

  5. Physiological and biochemical characteristics of laboratory induced mutants of Botrytis cinerea with resistance to fluazinam.

    Science.gov (United States)

    Shao, Wenyong; Zhang, Yu; Ren, Weichao; Chen, Changjun

    2015-01-01

    Botrytis cinerea is a necrotrophic and filamentous fungus with a high risk of developing resistance to fungicides. The pyridinamine fungicide fluazinam has been reported to have excellent activity against B. cinerea and better effect on controlling gray mold. In this study, the physiological and biochemical characteristics of laboratory-induced mutants of B. cinerea with resistance to fluazinam has been investigated. Compared to the wild-type strains, the fluazinam-resistant mutants had a significant decrease in respiratory rate, glycerol, oxalate, and ATP contents, and an increase in ATPase activity and sensitivity to osmotic pressure, but did not differ in cell membrane permeability. Sequencing indicated that two parental strains and four resistant mutants were identical in the nucleotide sequence of F-ATPase gene. These results will enrich our understanding of the resistance mechanism of B. cinerea to fluazinam. Copyright © 2014 Elsevier Inc. All rights reserved.

  6. Antibiotics resistance of Stenotrophomonas maltophilia strains ...

    African Journals Online (AJOL)

    Introduction. Stenotrophomonas maltophilia is a resistant pathogen that can cause bacteremia, endocarditis, respiratory system, central nervous system and urinary tract infections in patients with risk factors like malignancy or neutrope- nia, use of broad-spectrum antibiotics like carbapenem or long-term hospitalization1,2.

  7. Haplopappus gracilis cell strains resistant to pyrimidine analogues.

    Science.gov (United States)

    Jones, G E; Hann, J

    1979-03-01

    Strains of Haplopappus gracilis (Nutt.) Gray cells resistant to 6-azauracil have been isolated from cultures of diploid cells. These strains are also resistant to 8-azaguanine, as is their parent. The variants are 100- to 125-fold more resistant to 6-azauracil than their parent, and they exhibit different spectra of cross resistance to other pyrimidine analogues. The phenotype of each variant is stable in the absence of selection. The majority of cells in cultures of the variants are diploid; all others examined were tetraploid. Initial rates of uptake of uracil are not reduced in the variants. Fluorouracil, to which two variants are resistant, is taken up by one of them as well as by the parent. Responses of the other two to fluorouracil are not correlated with decreased ability to accumulate this analogue.

  8. The MG1363 and IL1403 Laboratory Strains of Lactococcus lactis and Several Dairy Strains Are Diploid▿ †

    OpenAIRE

    Michelsen, Ole; Hansen, Flemming G.; Albrechtsen, Bjarne; Jensen, Peter Ruhdal

    2009-01-01

    Bacteria are normally haploid, maintaining one copy of their genome in one circular chromosome. We have examined the cell cycle of laboratory strains of Lactococcus lactis, and, to our surprise, we found that some of these strains were born with two complete nonreplicating chromosomes. We determined the cellular content of DNA by flow cytometry and by radioactive labeling of the DNA. These strains thus fulfill the criterion of being diploid. Several dairy strains were also found to be diploid...

  9. Methicillin-resistant septal peptidoglycan synthesis in a methicillin-resistant Staphylococcus aureus strain.

    OpenAIRE

    Wilkinson, B J; Nadakavukaren, M J

    1983-01-01

    In a methicillin-resistant Staphylococcus aureus strain, electron micrographs showed that cell wall septa continued to be formed in the presence of methicillin, although they became distorted and enlarged. The results indicated that peripheral cell wall synthesis was inhibited. It is concluded that a methicillin-resistant mode of septal peptidoglycan synthesis is an important determinant of methicillin resistance.

  10. Colistin Resistance in Carbapenem-Resistant Klebsiella pneumoniae: Laboratory Detection and Impact on Mortality.

    Science.gov (United States)

    Rojas, Laura J; Salim, Madiha; Cober, Eric; Richter, Sandra S; Perez, Federico; Salata, Robert A; Kalayjian, Robert C; Watkins, Richard R; Marshall, Steve; Rudin, Susan D; Domitrovic, T Nicholas; Hujer, Andrea M; Hujer, Kristine M; Doi, Yohei; Kaye, Keith S; Evans, Scott; Fowler, Vance G; Bonomo, Robert A; van Duin, David

    2017-03-15

    Polymyxins including colistin are an important "last-line" treatment for infections caused by carbapenem-resistant Klebsiella pneumoniae (CRKp). Increasing use of colistin has led to resistance to this cationic antimicrobial peptide. A cohort nested within the Consortium on Resistance against Carbapenems in Klebsiella pneumoniae (CRACKLE) was constructed of patients with infection, or colonization with CRKp isolates tested for colistin susceptibility during the study period of December, 2011 to October, 2014. Reference colistin resistance determination as performed by broth macrodilution was compared to results from clinical microbiology laboratories (Etest) and to polymyxin resistance testing. Each patient was included once, at the time of their first colistin-tested CRKp positive culture. Time to 30-day in-hospital all-cause mortality was evaluated by Kaplan-Meier curves and Cox proportional hazard modeling. In 246 patients with CRKp, 13% possessed ColR CRKp. ColR was underestimated by Etest (very major error rate = 35%, major error rate = 0.4%). A variety of rep-PCR strain types were encountered in both the ColS and the ColR groups. Carbapenem resistance was mediated primarily by blaKPC-2 (46%) and blaKPC-3 (50%). ColR was associated with increased hazard for in-hospital mortality (aHR 3.48; 95% confidence interval, 1.73-6.57; P < .001). The plasmid-associated ColR genes, mcr-1 and mcr-2 were not detected in any of the ColR CRKp. In this cohort, 13% of patients with CRKp presented with ColR CRKp. The apparent polyclonal nature of the isolates suggests de novo emergence of ColR in this cohort as the primary factor driving ColR. Importantly, mortality was increased in patients with ColR isolates.

  11. Detection of antibiotic resistance in clinical bacterial strains from pets

    OpenAIRE

    Poeta, P.; Rodrigues, J.

    2008-01-01

    The identification of different bacterial strains and the occurrence of antibiotic resistance were investigated in several infection processes of pets as skin abscess with purulent discharge, bronco alveolar fluid, earwax, urine, mammary, and eye fluid. Streptococcus spp. and Staphylococcus spp. were the most detected in the different samples. A high frequency of antimicrobial resistance has been observed and this could reflect the wide use of antimicrobials in pets, making the effectiveness ...

  12. Emerging azithromycin-resistance among the Neisseria gonorrhoeae strains isolated in Hungary.

    Science.gov (United States)

    Brunner, Alexandra; Nemes-Nikodem, Eva; Jeney, Csaba; Szabo, Dora; Marschalko, Marta; Karpati, Sarolta; Ostorhazi, Eszter

    2016-09-20

    In the 1990s, azithromycin became the drug of choice for many infectious diseases but emerging resistance to the drug has only been reported in the last decade. In the last 5 years, the National Neisseria gonorrhoeae Reference Laboratory of Hungary (NNGRLH) has also observed an increased number of N. gonorrhoeae strains resistant to azithromycin. The aim of this study was to determine the most frequent sequence types (ST) of N. gonorrhoeae related to elevated levels of azithromycin MIC (minimal inhibitory concentration). Previously and currently isolated azithromycin-resistant strains have been investigated for the existence of molecular relationship. Maldi-Tof technic was applied for the identification of the strains isolated from outpatients attending the reference laboratory. Testing antibiotic susceptibility of azithromycin, cefixime, ceftriaxone, tetracycline, spectinomycin and ciprofloxacin was carried out for all the identified strains, using MIC strip test Liofilchem(®). N. gonorrhoeae multiantigen sequence typing (NG-MAST) was performed exclusively on azithromycin-resistant isolates. A phylogenetic tree was drawn using MEGA6 (Molecular Evolutionary Genetics Analysis Version 6.0) Neighbour-Joining method. Out of 192 N. gonorrhoeae isolates, 30.0 % (58/192) proved resistant to azithromycin (MIC > 0.5 mg/L). Of the azithromycin-resistant isolates, ST1407, ST4995 and ST11064 were the most prevalent. Based on the phylogenetic analysis, the latter two STs are closely related. In contrast to West-European countries, in our region, resistance to azithromycin has increased up to 30 % in the last 5 years, so the recommendation of the European Guideline -500 mg of ceftriaxone combined with 2 g of azithromycin as first choice therapy against N. gonorrhoeae- should be seriously considered in case of Hungary.

  13. Thermal strain measurement of EAST W/Cu divertor structure using electric resistance strain gauges

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Xingli [Institute of Plasma Physics, Chinese Academy of Sciences, Hefei, 230031 (China); Science Island Branch of Graduate School, University of Science & Technology of China, Hefei, 230031 (China); Wang, Wanjing, E-mail: wjwang@ipp.ac.cn [Institute of Plasma Physics, Chinese Academy of Sciences, Hefei, 230031 (China); Wang, Jichao [Institute of Plasma Physics, Chinese Academy of Sciences, Hefei, 230031 (China); Wei, Ran; Sun, Zhaoxuan [Institute of Plasma Physics, Chinese Academy of Sciences, Hefei, 230031 (China); Science Island Branch of Graduate School, University of Science & Technology of China, Hefei, 230031 (China); Li, Qiang; Xie, Chunyi [Institute of Plasma Physics, Chinese Academy of Sciences, Hefei, 230031 (China); Chen, Hong-En; Wang, Kaiqiang; Wu, Lei; Chen, Zhenmao [State Key Lab for Strength and Vibration of Mechanical Structures, Xi’an Jiaotong University (China); Luo, Guang-Nan [Institute of Plasma Physics, Chinese Academy of Sciences, Hefei, 230031 (China); Science Island Branch of Graduate School, University of Science & Technology of China, Hefei, 230031 (China); Hefei Center for Physical Science and Technology, Hefei, 230022 (China); Hefei Science Center of Chinese Academy of Sciences, Hefei, 230027 (China)

    2016-12-15

    Highlights: • To understand the service behavior of W/Cu divertor, an electrical resistance strain gauge system had been introduced in a thermal strain measurement experiment. • The measurement system successfully finished the experiment and obtained valued thermal strain data. • Two thermomechanical analyses had also been carried out and compared with the measurement results. • Experiment results corresponded well to simulations and threw a light upon the failure of W/Cu divertor in the previous baking tests. - Abstract: W/Cu divertor has complex structure and faces extreme work environment in EAST Tokamak device. To measure its thermal strain shall be a valued way to understand its service behavior and then optimize its design and manufacturing process. This work presents a preliminary study on measuring thermal strain of EAST W/Cu divertor structure using electric resistance strain gauges. Eight gauges had been used in the experiment and the heating temperature had been set to 230 °C with respect to the work temperature. To realize the measuring experiment, an appropriate fixing method of gauges in divertor narrow spaces had been taken and tested, which could not only withstand high temperature but also had no damage to the divertor sample. The measurement results were that three gauges showed positive strain while other three showed negative strain after having been compensated, which corresponded to tensile stress and compressed stress respectively. Two thermomechanical simulations had also been carried out and used for comparing with the experiment.

  14. Resistance of functional Lactobacillus plantarum strains against food stress conditions.

    Science.gov (United States)

    Ferrando, Verónica; Quiberoni, Andrea; Reinhemer, Jorge; Suárez, Viviana

    2015-06-01

    The survival of three Lactobacillus plantarum strains (Lp 790, Lp 813 and Lp 998) with functional properties was studied taking into account their resistance to thermal, osmotic and oxidative stress factors. Stress treatments applied were: 52 °C-15 min (Phosphate Buffer pH 7, thermal shock), H2O2 0.1% (p/v) - 30 min (oxidative shock) and NaCl aqueous solution at 17, 25 and 30% (p/v) (room temperature - 1 h, osmotic shock). The osmotic stress was also evaluated on cell growth in MRS broth added of 2, 4, 6, 8 and 10% (p/v) of NaCl, during 20 h at 30 °C. The cell thermal adaptation was performed in MRS broth, selecting 45 °C for 30 min as final conditions for all strains. Two strains (Lp 813 and Lp 998) showed, in general, similar behaviour against the three stress factors, being clearly more resistant than Lp 790. An evident difference in growth kinetics in presence of NaCl was observed between Lp 998 and Lp 813, Lp998 showing a higher optical density (OD570nm) than Lp 813 at the end of the assay. Selected thermal adaptation improved by 2 log orders the thermal resistance of both strains, but cell growth in presence of NaCl was enhanced only in Lp 813. Oxidative resistance was not affected with this thermal pre-treatment. These results demonstrate the relevance of cell technological resistance when selecting presumptive "probiotic" cultures, since different stress factors might considerably affect viability or/and performance of the strains. The incidence of stress conditions on functional properties of the strains used in this work are currently under research in our group. Copyright © 2014 Elsevier Ltd. All rights reserved.

  15. Distribution of the Strains of Multidrug-resistant, Extensively Drug-resistant, and Pandrug-resistant Pseudomonas aeruginosa Isolates from Burn Patients

    Directory of Open Access Journals (Sweden)

    Hajieh Ghasemian Safaei

    2017-01-01

    Full Text Available Background: Pseudomonas aeruginosa is an opportunistic and Gram-negative pathogen that is used as the most important factor in burn wound infections, and due to the rapid acquisition of multidrug resistance (MDR, it causes high mortality rates in these sectors. Thus, diagnosis and assessment of antibiotic resistance patterns are very important in these patients. The aim of this study was to evaluate antibiotic resistance pattern and determining P. aeruginosa MDR. Materials and Methods: In this study, phenotypic, biochemical, and polymerase chain reaction tests were used to identify P. aeruginosa from 120 wound burn samples that 96 samples were detected to P. aeruginosa species. In the next step, according to the Clinical and Laboratory Standard Institute standard guidelines, antibiogram test was performed by disk diffusion method for amikacin, ciprofloxacin, norfloxacin, gentamicin, cefepime, aztreonam, meropenem, colistin, ceftazidime, and piperacillin-tazobactam antibiotics. Antibiotic data were analyzed by WHONET software; finally, the rate of antibiotic resistance and MDR strains was determined. Results: The highest antibiotic resistance belonged to amikacin (94.8% and norfloxacin (90.6%; in contrast, colistin (8.3% had the lowest and the MDR strains were MDR (95.8% and extensively drug resistance (XDR (87.5%. Conclusion: In this study, there was MDR with an alarming rate including MDR (95.8%, XDR (87.5%, and pan-drug resistance (0%. As a result, given antibiotics to patients should be controlled by the antibiogram results to avoid increasing MDR strains.

  16. Comprehensive study of proteasome inhibitors against Plasmodium falciparum laboratory strains and field isolates from Gabon

    Directory of Open Access Journals (Sweden)

    Kremsner Peter G

    2008-09-01

    Full Text Available Abstract Background The emergence and spread of Plasmodium falciparum resistance to almost all available antimalarial drugs necessitates the search for new chemotherapeutic compounds. The ubiquitin/proteasome system plays a major role in overall protein turnover, especially in fast dividing eukaryotic cells including plasmodia. Previous studies show that the 20S proteasome is expressed and catalytically active in plasmodia and treatment with proteasome inhibitors arrests parasite growth. This is the first comprehensive screening of proteasome inhibitors with different chemical modes of action against laboratory strains of P. falciparum. Subsequently, a selection of inhibitors was tested in field isolates from Lambaréné, Gabon. Methods Epoxomicin, YU101, YU102, MG132, MG115, Z-L3-VS, Ada-Ahx3-L3-VS, lactacystin, bortezomib (Velcade®, gliotoxin, PR11 and PR39 were tested and compared to chloroquine- and artesunate-activities in a standardized in vitro drug susceptibility assay against P. falciparum laboratory strains 3D7, D10 and Dd2. Freshly obtained field isolates from Lambaréné, Gabon, were used to measure the activity of chloroquine, artesunate, epoxomicin, MG132, lactacystin and bortezomib. Parasite growth was detected through histidine-rich protein 2 (HRP2 production. Raw data were fitted by a four-parameter logistic model and individual inhibitory concentrations (50%, 90%, and 99% were calculated. Results Amongst all proteasome inhibitors tested, epoxomicin showed the highest activity in chloroquine-susceptible (IC50: 6.8 nM [3D7], 1.7 nM [D10] and in chloroquine-resistant laboratory strains (IC50: 10.4 nM [Dd2] as well as in field isolates (IC50: 8.5 nM. The comparator drug artesunate was even more active (IC50: 1.0 nM, whereas all strains were chloroquine-resistant (IC50: 113 nM. Conclusion The peptide α',β'-epoxyketone epoxomicin is highly active against P. falciparum regardless the grade of the parasite's chloroquine

  17. Study of Klebsiella pneumoniae strains resistant to carbapenems isolated from blood in eastern Liguria

    Directory of Open Access Journals (Sweden)

    Giulia Carnesecchi

    2012-12-01

    Full Text Available Objectives. Study of multi-resistant Klebsiella pneumoniae strains isolated from blood cultures collected from in-patients of hospitals located in eastern Liguria, and evaluation of the susceptibility to carbapenems and other antibiotics by E-test and automated methods. Methods. At the Laboratory of Clinical Microbiology, of Lavagna Hospital in eastern Liguria, 397 Klebsiella pneumoniae strains were collected from in-patients from different wards of hospitals sites, during the year 2011. They included 115 isolates from blood cultures (aerobic and anaerobic and various biological materials. All strains were tested in the laboratory for their susceptibility to antibiotics. Results. Of the 115 strains of Klebsiella pneumoniae collected from blood cultures 59.1% showed resistance to imipenem, ertapenem, meropenem. Conclusions. The data show a high incidence of resistance to carbapenems in Klebsiella pneumoniae isolated from blood cultures.This is important to implement surveillance programs for control and prevention, but also reduce the intake of antibiotics when they are not strictly necessary.

  18. Heat resistance of an outbreak strain of Listeria monocytogenes in hot dog batter.

    Science.gov (United States)

    Mazzotta, A S; Gombas, D E

    2001-03-01

    The heat resistance of a strain of Listeria monocytogenes responsible for a listeriosis outbreak in hot dogs was not higher than the heat resistance of other L. monocytogenes strains when tested in tryptic soy broth and in laboratory-prepared hot dog batter. For the thermal death time experiments, the cells were grown to stationary phase or were starved in phosphate-buffered saline, pH 7, for 6 h at 30 degrees C. Starvation increased the heat resistance of L. monocytogenes in broth but not in hot dog batter. D-values in hot dog batter were higher than in broth. For the hot dog formulation used in this study, cooking the hot dog batter for 30 s at 71.1 degrees C (160 degrees F), or its equivalent using a z-value of 6 degrees C (11 degrees F), would inactivate 5 logs of L. monocytogenes.

  19. Herb-resistant UPEC strains have different biofilm formation abilities ...

    African Journals Online (AJOL)

    Background: The mechanisms and patterns of drug resistances of E. coli strains that cause uncomplicated urinary tract infections (UTIs) vary considerably. The emerging herbresistance of uropathogenic Escherichia coli (UPEC) has been a serious health problem, yet with unknown underlying mechanisms. Methods: To ...

  20. Strain diversity and phage resistance in complex dairy starter cultures

    NARCIS (Netherlands)

    Spus, M.; Alexeeva, S.V.; Wolkers-Rooijackers, J.C.M.; Zwietering, M.H.; Abee, T.; Smid, E.J.

    2015-01-01

    The compositional stability of the complex Gouda cheese starter culture Ur is thought to be influenced by diversity in phage resistance of highly related strains that co-exist together with bacteriophages. To analyze the role of bacteriophages in maintaining culture diversity at the level of genetic

  1. Induction of Streptomycin Uptake in Resistant Strains of Escherichia coli

    Science.gov (United States)

    Höltje, Joachim-Volker

    1979-01-01

    Different streptomycin-resistant strains of Escherichia coli, including an R100 plasmid-carrying strain of E. coli W3110, the ribosomally resistant mutant SM10, and the spontaneous revertant from dependence to independence d1023, exhibited poor accumulation capacity for aminoglycoside antibiotics. This was due to a failure of these mutants to induce the general polyamine transport system that is utilized by streptomycin to enter the cell. It is shown that the aminoglycoside kanamycin, which is effective on these streptomycin-resistant strains, was capable of inducing the uptake of streptomycin, thus giving rise to streptomycin accumulation up to wild-type levels. Plasmid-determined resistance, which has been speculated to be the result of a blockage of the uptake system by modified antibiotic molecules, cannot be overcome by the induction of streptomycin transport. Increase in permeability of the antibiotic does not affect the susceptibility of the bacteria. It is shown that all of the antibiotic taken up was enzymatically modified. R-plasmid-conferred resistance to aminoglycosides is therefore explained by the inactivation of the antibiotic entering the bacterial cell. PMID:371542

  2. Insecticide Resistance and Metabolic Mechanisms Involved in Larval and Adult Stages of Aedes aegypti Insecticide-Resistant Reference Strains from Cuba.

    Science.gov (United States)

    Bisset, Juan Andrés; Rodríguez, María Magdalena; French, Leydis; Severson, David W; Gutiérrez, Gladys; Hurtado, Daymi; Fuentes, Ilario

    2014-12-01

    Studies were conducted to compare levels of insecticide resistance and to determine the metabolic resistance mechanisms in larval and adult stages of Aedes aegypti from Cuba. Three insecticide-resistant reference strains of Ae. aegypti from Cuba were examined. These strains were derived from a Santiago de Cuba strain isolated in 1997; it was previously subjected to a strong selection for resistance to temephos (SAN-F6), deltamethrin (SAN-F12), and propoxur (SAN-F13) and routinely maintained in the laboratory under selection pressure up to the present time, when the study was carried out. In addition, an insecticide-susceptible strain was used for comparison. The insecticide resistance in larvae and adults was determined using standard World Health Organization methodologies. Insecticide resistance mechanisms were determined by biochemical assays. The esterases (α EST and β EST) and mixed function oxidase (MFO) activities were significantly higher in adults than in the larvae of the three resistant strains studied. The association of resistance level with the biochemical mechanism for each insecticide was established for each stage. The observed differences between larval and adult stages of Ae. aegypti in their levels of insecticide resistance and the biochemical mechanisms involved should be included as part of monitoring and surveillance activities in Ae. aegypti vector control programs.

  3. Resistance of Animal Strains of Pseudomonas aeruginosa to Carbapenems

    Science.gov (United States)

    Haenni, Marisa; Bour, Maxime; Châtre, Pierre; Madec, Jean-Yves; Plésiat, Patrick; Jeannot, Katy

    2017-01-01

    Carbapenems are major antibiotics reserved to human medicine. This study aimed to investigate the mechanisms of carbapenem resistance of a selection of Pseudomonas aeruginosa veterinary strains from the French network Resapath. Thirty (5.7%) imipenem and/or meropenem non-susceptible P. aeruginosa of canine (n = 24), feline (n = 5), or bovine (n = 1) origin were identified in a large collection of 527 veterinary strains gathered by the Resapath. These resistant isolates belonged to 25 MultiLocus Sequence Types (MLST), of which 17 (68%) are shared with clinical (human) strains, such as high risk clones ST233 and ST395. Interestingly, none of the veterinary strains produced a carbapenemase, and only six of them (20%) harbored deletions or insertion sequence (IS) disrupting the porin OprD gene. The remaining 24 strains contained mutations or IS in various loci resulting in down-regulation of gene oprD coupled with upregulation of efflux system CzcCBA (n = 3; activation of sensor kinase CzcS ± CopS), MexEF-OprN (n = 4; alteration of oxido reductase MexS), MexXY (n = 8; activation of two-component system ParRS), or MexAB-OprM (n = 12; alteration of regulator MexR, NalC ± NalD). Two efflux pumps were co-produced simultaneously in three mutants. Finally, in 11 out of 12 strains displaying an intact porin OprD, derepression of MexAB-OprM accounted for a decreased susceptibility to meropenem relative to imipenem. Though not treated by carbapenems, animals thus represent a reservoir of multidrug resistant P. aeruginosa strains potentially able to contaminate fragile outpatients. PMID:29033910

  4. Resistance of Animal Strains of Pseudomonas aeruginosa to Carbapenems

    Directory of Open Access Journals (Sweden)

    Marisa Haenni

    2017-09-01

    Full Text Available Carbapenems are major antibiotics reserved to human medicine. This study aimed to investigate the mechanisms of carbapenem resistance of a selection of Pseudomonas aeruginosa veterinary strains from the French network Resapath. Thirty (5.7% imipenem and/or meropenem non-susceptible P. aeruginosa of canine (n = 24, feline (n = 5, or bovine (n = 1 origin were identified in a large collection of 527 veterinary strains gathered by the Resapath. These resistant isolates belonged to 25 MultiLocus Sequence Types (MLST, of which 17 (68% are shared with clinical (human strains, such as high risk clones ST233 and ST395. Interestingly, none of the veterinary strains produced a carbapenemase, and only six of them (20% harbored deletions or insertion sequence (IS disrupting the porin OprD gene. The remaining 24 strains contained mutations or IS in various loci resulting in down-regulation of gene oprD coupled with upregulation of efflux system CzcCBA (n = 3; activation of sensor kinase CzcS ± CopS, MexEF-OprN (n = 4; alteration of oxido reductase MexS, MexXY (n = 8; activation of two-component system ParRS, or MexAB-OprM (n = 12; alteration of regulator MexR, NalC ± NalD. Two efflux pumps were co-produced simultaneously in three mutants. Finally, in 11 out of 12 strains displaying an intact porin OprD, derepression of MexAB-OprM accounted for a decreased susceptibility to meropenem relative to imipenem. Though not treated by carbapenems, animals thus represent a reservoir of multidrug resistant P. aeruginosa strains potentially able to contaminate fragile outpatients.

  5. Resistance of Animal Strains ofPseudomonas aeruginosato Carbapenems.

    Science.gov (United States)

    Haenni, Marisa; Bour, Maxime; Châtre, Pierre; Madec, Jean-Yves; Plésiat, Patrick; Jeannot, Katy

    2017-01-01

    Carbapenems are major antibiotics reserved to human medicine. This study aimed to investigate the mechanisms of carbapenem resistance of a selection of Pseudomonas aeruginosa veterinary strains from the French network Resapath. Thirty (5.7%) imipenem and/or meropenem non-susceptible P. aeruginosa of canine ( n = 24), feline ( n = 5), or bovine ( n = 1) origin were identified in a large collection of 527 veterinary strains gathered by the Resapath. These resistant isolates belonged to 25 MultiLocus Sequence Types (MLST), of which 17 (68%) are shared with clinical (human) strains, such as high risk clones ST233 and ST395. Interestingly, none of the veterinary strains produced a carbapenemase, and only six of them (20%) harbored deletions or insertion sequence (IS) disrupting the porin OprD gene. The remaining 24 strains contained mutations or IS in various loci resulting in down-regulation of gene oprD coupled with upregulation of efflux system CzcCBA ( n = 3; activation of sensor kinase CzcS ± CopS), MexEF-OprN ( n = 4; alteration of oxido reductase MexS), MexXY ( n = 8; activation of two-component system ParRS), or MexAB-OprM ( n = 12; alteration of regulator MexR, NalC ± NalD). Two efflux pumps were co-produced simultaneously in three mutants. Finally, in 11 out of 12 strains displaying an intact porin OprD, derepression of MexAB-OprM accounted for a decreased susceptibility to meropenem relative to imipenem. Though not treated by carbapenems, animals thus represent a reservoir of multidrug resistant P. aeruginosa strains potentially able to contaminate fragile outpatients.

  6. The MG1363 and IL1403 Laboratory Strains of Lactococcus lactis and Several Dairy Strains Are Diploid▿ †

    Science.gov (United States)

    Michelsen, Ole; Hansen, Flemming G.; Albrechtsen, Bjarne; Jensen, Peter Ruhdal

    2010-01-01

    Bacteria are normally haploid, maintaining one copy of their genome in one circular chromosome. We have examined the cell cycle of laboratory strains of Lactococcus lactis, and, to our surprise, we found that some of these strains were born with two complete nonreplicating chromosomes. We determined the cellular content of DNA by flow cytometry and by radioactive labeling of the DNA. These strains thus fulfill the criterion of being diploid. Several dairy strains were also found to be diploid while a nondairy strain and several other dairy strains were haploid in slow-growing culture. The diploid and haploid strains differed in their sensitivity toward UV light, in their cell size, and in their D period, the period between termination of DNA replication and cell division. PMID:20023021

  7. The MG1363 and IL1403 laboratory strains of Lactococcus lactis and several dairy strains are diploid.

    Science.gov (United States)

    Michelsen, Ole; Hansen, Flemming G; Albrechtsen, Bjarne; Jensen, Peter Ruhdal

    2010-02-01

    Bacteria are normally haploid, maintaining one copy of their genome in one circular chromosome. We have examined the cell cycle of laboratory strains of Lactococcus lactis, and, to our surprise, we found that some of these strains were born with two complete nonreplicating chromosomes. We determined the cellular content of DNA by flow cytometry and by radioactive labeling of the DNA. These strains thus fulfill the criterion of being diploid. Several dairy strains were also found to be diploid while a nondairy strain and several other dairy strains were haploid in slow-growing culture. The diploid and haploid strains differed in their sensitivity toward UV light, in their cell size, and in their D period, the period between termination of DNA replication and cell division.

  8. The MG1363 and IL1403 Laboratory Strains of Lactococcus lactis and Several Dairy Strains Are Diploid

    DEFF Research Database (Denmark)

    Michelsen, Ole; Hansen, Flemming G.; Albrechtsen, B.

    2010-01-01

    Bacteria are normally haploid, maintaining one copy of their genome in one circular chromosome. We have examined the cell cycle of laboratory strains of Lactococcus lactis, and, to our surprise, we found that some of these strains were born with two complete nonreplicating chromosomes. We...... determined the cellular content of DNA by flow cytometry and by radioactive labeling of the DNA. These strains thus fulfill the criterion of being diploid. Several dairy strains were also found to be diploid while a nondairy strain and several other dairy strains were haploid in slow-growing culture....... The diploid and haploid strains differed in their sensitivity toward UV light, in their cell size, and in their D period, the period between termination of DNA replication and cell division....

  9. Antibiotics resistance of Stenotrophomonas maltophilia strains isolated from various clinical specimens.

    Science.gov (United States)

    Çıkman, Aytekin; Parlak, Mehmet; Bayram, Yasemin; Güdücüoğlu, Hüseyin; Berktaş, Mustafa

    2016-03-01

    A limited number of antibiotics are recommended for the therapy of Stenotrophomonas maltophilia infections due to therapy difficulties caused by its numerous mechanisms of resistance. In this study conducted over a period of approximately 5 years we aimed to determine resistance rates of S. maltophilia based on drug classification recommended by Clinical and Laboratory Standards Institute. A total of 118 S. maltophilia strains isolated from various clinical specimens between January 2006 and June 2012 were included in the study. BD Phoenixautomated microbiology system (Becton Dickinson, USA) was utilized for species level identification and antibiotic susceptibility testing. Sixty seven of S. maltophilia strains were isolated from tracheal aspirate isolates, 17 from blood, 10 from sputum, 10 from wound and 14 from other clinical specimens. Levofloxacin was found to be the most effective antibiotic against S. maltophilia strains with resistance rate of 7.6%. The resistance rates to other antibiotics were as follows: chloramphenicol 18.2%, trimethoprim-sulfamethoxazole 20.3% and ceftazidime 72%. The study revealed that S. maltophilia is resistant to many antibiotics. The treatment of infections caused by S. maltophilia should be preferred primarily as levofloxacin, chloramphenicol, and TMP-SXT, respectively.

  10. Full-Genome Sequencing Identifies in the Genetic Background Several Determinants That Modulate the Resistance Phenotype in Methicillin-Resistant Staphylococcus aureus Strains Carrying the NovelmecCGene.

    Science.gov (United States)

    Milheiriço, Catarina; de Lencastre, Hermínia; Tomasz, Alexander

    2017-03-01

    Most methicillin-resistant Staphylococcus aureus (MRSA) strains are resistant to beta-lactam antibiotics due to the presence of the mecA gene, encoding an extra penicillin-binding protein (PBP2A) that has low affinity for virtually all beta-lactam antibiotics. Recently, a new resistance determinant-the mecC gene-was identified in S. aureus isolates recovered from humans and dairy cattle. Although having typically low MICs to beta-lactam antibiotics, MRSA strains with the mecC determinant are also capable of expressing high levels of oxacillin resistance when in an optimal genetic background. In order to test the impact of extensive beta-lactam selection on the emergence of mecC -carrying strains with high levels of antibiotic resistance, we exposed the prototype mecC -carrying MRSA strain, LGA251, to increasing concentrations of oxacillin. LGA251 was able to rapidly adapt to high concentrations of oxacillin in growth medium. In such laboratory mutants with increased levels of oxacillin resistance, we identified mutations in genes with no relationship to the mecC regulatory system, indicating that the genetic background plays an important role in the establishment of the levels of oxacillin resistance. Our data also indicate that the stringent stress response plays a critical role in the beta-lactam antibiotic resistance phenotype of MRSA strains carrying the mecC determinant. Copyright © 2017 American Society for Microbiology.

  11. Resistance Mechanisms in an In Vitro-Selected Amoxicillin-Resistant Strain of Helicobacter pylori▿

    OpenAIRE

    Co, Edgie-Mark A.; Schiller, Neal L.

    2006-01-01

    We investigated the β-lactam resistance mechanism(s) of an in vitro-selected amoxicillin-resistant Helicobacter pylori strain (AmoxR). Our results demonstrated that resistance is due to a combination of amino acid substitutions in penicillin binding protein 1 (PBP1), HopB, and HopC identified in AmoxR, resulting in decreased affinity of PBP1 for amoxicillin and decreased accumulation of penicillin.

  12. Rapid identification of Mycobacterium avium ssp paratuberculosis laboratory strains by IS900-Nested polymerase chain reaction

    Directory of Open Access Journals (Sweden)

    Mohammad Mohammad Taheri

    2016-01-01

    Conclution: However, no amplification was observed with other strains. Two main achievements of this work are the development of an efficient means of differentiation between the six Razi laboratory mycobacterial strains and characterization of the genomic profile of these strains, a capability that is vital when cross contamination is potentially an important concern.

  13. Characterization of methicillin resistant Staphylococcus aureus strains among inpatients and outpatients in a referral hospital in Tehran, Iran.

    Science.gov (United States)

    Rahimi, Fateh; Shokoohizadeh, Leili

    2016-08-01

    Methicillin resistant Staphylococcus aureus is one of the most common causes of a variety of infections ranging from wound infections to urinary tract infections (UTI) in hospital and community. In this study during 3 years we characterized the antibiotic resistance patterns of 491 hospital acquired MRSA and community associated MRSA strains by the guidelines of clinical and laboratory standard institute. A combination of high resolution PhP typing method and SCCmec typing were used for clonal dissemination of isolates. Among all 491 MRSA strains, diverse PhP types consisting of 29 common types (CTs) and 4 single types (STs) and also 2 different SCCmec types (III and IVa) were detected. In addition, 18 CTs were common among CA- and HA-MRSA strains and the presence of all 4 STs was limited to HA-MRSA strains. All isolates were resistant to penicillin and high level resistance was observed against ciprofloxacin, erythromycin, tobramycin and kanamycin and the rate of resistance to most of the antibiotic tested among HA-MRSA was significantly higher than CA-MRSA isolates. Moreover, all isolates showed susceptibility to linezolid, vancomycin and quinupristin-dalfopristin and very low resistance to fusidic acid, nitrofurantoin and chloramphenicol were detected. Our findings illustrated the increasing rate of clonal dissemination and persistence of highly antibiotic resistant CA-MRSA strains in Tehran hospitals, and also indicated the important role of the hospitals as the reservoir of MRSA strains. Copyright © 2016 Elsevier Ltd. All rights reserved.

  14. Antimicrobial susceptibility of Bifidobacterium breve strains and genetic analysis of streptomycin resistance of probiotic B. breve strain Yakult.

    Science.gov (United States)

    Kiwaki, Mayumi; Sato, Takashi

    2009-09-15

    The minimum inhibitory concentrations (MICs) of 17 antimicrobials for 26 Bifidobacterium breve strains of various origins were determined by broth microdilution. MIC distributions for 17 antimicrobials except streptomycin and tetracycline were unimodal for all strains tested, whereas bimodal distributions were observed for streptomycin and tetracycline. The probiotic strain B. breve strain Yakult showed intrinsic susceptibility to all antimicrobials except streptomycin to which the strain showed an atypically higher MIC of >256 microg/ml. Because this strain is a commercial strain, which is often ingested by many consumers on a daily basis, it is very important to determine the genetic basis for streptomycin resistance of this strain. Molecular analysis revealed that a mutation of the rpsL gene for ribosomal protein S12 was responsible for this streptomycin resistance. The resistance of B. breve strain Yakult to streptomycin, therefore, is caused by a chromosomal mutation and very unlikely to be transferred to other microorganisms.

  15. Amoebicidal or amoebostatic influence of disinfectants used in health facilities and laboratories on corneal strains of Acanthamoeba

    Science.gov (United States)

    Baltaza, Wanda; Padzik, Marcin; Szaflik, Jacek P; Dybicz, Monika; Hendiger, Edyta; Chomicz, Lidia

    Different Acanthamoeba species are amphizoic organisms distributed in wide range of habitats in natural and man-made environments; they are also detected on surfaces of equipment and accessories in health facilities. Some strains of the amoebae are causative agents of the vision-threatening human disease Acanthamoeba keratitis, mainly reported in contact lens wearers. An exceptional high resistance of Acanthamoeba trophozoites and particularly cysts to chemicals, disinfectants and drugs is believed as influencing difficulty resulting in unsuccessful therapeutic management. As Acanthamoeba keratitis is the serious medical problem worldwide, different chemicals with possible activity against environmental and clinical Acanthamoeba strains are tested. In our study, selected disinfectants used in health care settings and laboratories were tested and their efficacy against the corneal strains Acanthamoeba castellanii and A. polyphaga , and environmental A. castellanii Neff strain was assessed. Comparative assessment of results of the assays show that, apart from amoebistatic effects, the disinfectants indicated expected cysticidal efficacy.

  16. Virulence and pathogenesis of the MSW and MSD strains of Californian myxoma virus in European rabbits with genetic resistance to myxomatosis compared to rabbits with no genetic resistance.

    Science.gov (United States)

    Silvers, L; Inglis, B; Labudovic, A; Janssens, P A; van Leeuwen, B H; Kerr, P J

    2006-04-25

    The pathogenesis of two Californian strains of myxoma virus (MSW and MSD) was examined in European rabbits (Oryctolagus cuniculus) that were either susceptible to myxomatosis (laboratory rabbits) or had undergone natural selection for genetic resistance to myxomatosis (Australian wild rabbits). MSW was highly lethal for both types of rabbits with average survival times of 7.3 and 9.4 days, respectively, and 100% mortality. Classical clinical signs of myxomatosis were not present except in one rabbit that survived for 13 days following infection. Previously described clinical signs of trembling and shaking were observed in laboratory but not wild rabbits. Despite the high resistance of wild rabbits to myxomatosis caused by South American strains of myxoma virus, the MSW strain was of such high virulence that it was able to overcome resistance. The acute nature of the infection, relatively low viral titers in the tissues and destruction of lymphoid tissues, suggested that death was probably due to an acute and overwhelming immunopathological response to the virus. No virus was found in the brain. The MSD strain was attenuated compared to previously published descriptions and therefore was only characterized in laboratory rabbits. It is concluded that Californian MSW strain of myxoma virus is at the extreme end of a continuum of myxoma virus virulence but that the basic pathophysiology of the disease induced is not broadly different to other strains of myxoma virus.

  17. Isolation of rifampicin resistant Flavobacterium psychrophilum strains and their potential as live attenuated vaccine candidates

    Science.gov (United States)

    Previous studies have demonstrated that passage of pathogenic bacteria on increasing concentrations of the antibiotic rifampicin leads to the attenuation of virulence and these resistant strains may serve as live attenuated vaccines. Two rifampicin resistant strains of Flavobacterium psychrophilum,...

  18. Outbreak of candidemia caused by fluconazole resistant Candida parapsilosis strains in an intensive care unit.

    Science.gov (United States)

    Pinhati, Henrique Marconi Sampaio; Casulari, Luiz Augusto; Souza, Ana Carolina Remondi; Siqueira, Ricardo Andreotti; Damasceno, Camila Maria Gomes; Colombo, Arnaldo Lopes

    2016-08-20

    Candidemia is an increasing problem in tertiary care hospitals worldwide. Here, we report the first outbreak of candidemia caused by fluconazole-resistant C. parapsilosis (FRCP) strains in Brazil. This was a cross-sectional study of clinical and microbiological data of all candidemic episodes diagnosed from July 2011 to February 2012 in a 200-bed tertiary care hospital. Initial yeast identification and susceptibility testing were performed using the VITEK 2 - System. Isolates of Candida spp. resistant to fluconazole were sent to a reference laboratory (LEMI-UNIFESP) for further molecular identification and confirmation of resistance by CLSI microdilution test. A multivariate analysis was conducted to identify factors associated with FRCP infection. We identified a total of 40 critically ill patients with candidemia (15 women) with a median age of 70 years. The incidence of candidemia was 6 cases/1,000 patients admissions, including 28 cases (70 %) of infection with C. parapsilosis, 21 of which (75 %) were resistant to fluconazole. In only 19 % of FRCP candidemia cases had fluconazole been used previously. The results of our study indicated that diabetes is a risk factor for FRCP candidemia (p = 0.002). Overall, mortality from candidemia was 45 %, and mortality from episodes of FRCP infections was 42.9 %. The clustering of incident cases in the ICU and molecular typing of strains suggest horizontal transmission of FRCP. Accurate vigilant monitoring for new nosocomial strains of FRCP is required.

  19. Antimicrobial resistance among invasive Haemophilus influenzae strains: results of a Brazilian study carried out from 1996 through 2000

    Directory of Open Access Journals (Sweden)

    Casagrande S.T.

    2002-01-01

    Full Text Available A total of 1712 strains of Haemophilus influenzae isolated from patients with invasive diseases were obtained from ten Brazilian states from 1996 to 2000. ß-Lactamase production was assessed and the minimum inhibitory concentrations (MIC of ampicillin, chloramphenicol, ceftriaxone and rifampin were determined using a method for broth microdilution of Haemophilus test medium. The prevalence of strains producing ß-lactamase ranged from 6.6 to 57.7%, with an overall prevalence of 18.4%. High frequency of ß-lactamase-mediated ampicillin resistance was observed in Distrito Federal (25%, São Paulo (21.7% and Paraná (18.5%. Of the 1712 strains analyzed, none was ß-lactamase negative, ampicillin resistant. A total of 16.8% of the strains were resistant to chloramphenicol, and 13.8% of these also presented resistance to ampicillin, and only 3.0% were resistant to chloramphenicol alone. All strains were susceptible to ceftriaxone and rifampin and the MIC90 were 0.015 µg/ml and 0.25 µg/ml, respectively. Ceftriaxone is the drug of choice for empirical treatment of bacterial meningitis in pediatric patients who have not been screened for drug susceptibility. The emergence of drug resistance is a serious challenge for the management of invasive H. influenzae disease, which emphasizes the fundamental role of laboratory-based surveillance for antimicrobial resistance.

  20. Laboratory methods for diagnosis and detection of drug resistant ...

    African Journals Online (AJOL)

    Data source: Published series of peer reviewed journals and manuals written on laboratory methods that are currently used for diagnosis and detection of drug resistance of Mycobacterium tuberculosis complex were reviewed using the index medicus, pubmed and medline search. Conventional bacteriological microscopy ...

  1. Laboratory Measurement of the Electrical Resistivity of some ...

    African Journals Online (AJOL)

    The electrical resistivity of fresh Pre-Cambrian to Upper Cambrian crystalline basement rocks in southwestern Nigeria, hitherto inferred from sounding interpretation, has been determined from laboratory measurements. The rock types consist of granite gneiss, banded gneiss, augen gneiss, biotite granite, charnockite, ...

  2. Dissemination of antibiotic resistance in methicillin-resistant Staphylococcus aureus and vancomycin-resistant S aureus strains isolated from hospital effluents.

    Science.gov (United States)

    Mandal, Santi M; Ghosh, Ananta K; Pati, Bikas R

    2015-12-01

    Vancomycin-resistant Staphylococcus aureus (VRSA) and methicillin-resistant S aureus (MRSA) strains were examined in hospital effluents. Most S aureus strains are resistant to methicillin (MRSA), followed by tetracycline. Approximately 15% of MRSA strains are also resistant to vancomycin (VRSA). All VRSA strains developed a VanR/VanS-regulated 2-component system of VanA-type resistance in their genome. Results indicate that there is a possibility of developing resistance to aminoglycosides by VRSA strains in the near future. Copyright © 2015 Association for Professionals in Infection Control and Epidemiology, Inc. Published by Elsevier Inc. All rights reserved.

  3. Multiply antibiotic-resistant Vibrio cholerae O1 biotype El Tor strains emerge during cholera outbreaks in Zambia.

    Science.gov (United States)

    Mwansa, J C L; Mwaba, J; Lukwesa, C; Bhuiyan, N A; Ansaruzzaman, M; Ramamurthy, T; Alam, M; Balakrish Nair, G

    2007-07-01

    Antibiotic resistance data, made available from laboratory records during eight cholera outbreaks between 1990 and 2004 showed Vibrio cholerae serogroup O1 to have a low level of resistance (2-3%) to tetracycline during 1990-1991. Resistance increased for tetracycline (95%), chloramphenicol (78%), doxycycline (70%) and trimethoprim-sulphamethoxazole (97%) in subsequent outbreaks. A significant drop in resistance to tetracycline and chloramphenicol followed the adoption of a national policy to replace tetracycline with erythromycin for treating cholera. Sixty-nine strains from cholera outbreaks in Zambia between 1996 and 2004, were examined for antibiotic resistance and basic molecular traits. A 140 MDa conjugative, multidrug-resistant plasmid was found to encode tetracycline resistance in strains from 1996/1997 whereas strains from 2003/2004 were resistant to furazolidone, but susceptible to tetracycline, and lacked this plasmid. PCR revealed 25 of 27 strains from 1996/1997 harboured the intl1 class 1 integron but lacked SXT, a conjugative transposon element. Similar screening of 42 strains from 2003/2004 revealed all carried SXT but not the intl1 class 1 integron. All 69 strains, except two, one lacking ctxA and the other rstR and thus presumably truncated in the CTX prophage region, were positive for important epidemic markers namely rfbO1, ctxA, rstR2, and tcpA of El Tor biotype. Effective cholera management is dependent on updated reports on culture and sensitivity to inform the choice of antibiotic. Since the emergence of antibiotic resistance may significantly influence strategies for controlling cholera, continuous monitoring of epidemic strains is crucial.

  4. Essential oils as potential adulticides against two populations of Aedes aegypti, the laboratory and natural field strains, in Chiang Mai province, northern Thailand.

    Science.gov (United States)

    Chaiyasit, Dana; Choochote, Wej; Rattanachanpichai, Eumporn; Chaithong, Udom; Chaiwong, Prasong; Jitpakdi, Atchariya; Tippawangkosol, Pongsri; Riyong, Doungrat; Pitasawat, Benjawan

    2006-11-01

    Essential oils derived from five plant species, celery (Apium graveolens), caraway (Carum carvi), zedoary (Curcuma zedoaria), long pepper (Piper longum), and Chinese star anise (Illicium verum), were subjected to investigation of adulticidal activity against mosquito vectors. Two populations of Aedes aegypti, the laboratory and natural field strains, collected in Chiang Mai province, northern Thailand were tested in pyrethroid-susceptibility bioassays. The results revealed that the natural field strain of A. aegypti was resistant to permethrin, with mortality rates ranging from 51 to 66%. A mild susceptibility, with mortality rates ranging from 82 to 88%, was observed in the natural field strain of A. aegypti exposed to lambdacyhalothrin, which suggested that this strain was tolerant and might be resistant to this insecticide. However, laboratory-reared A. aegypti exposed to discriminating dosages of permethrin and lambdacyhalothrin induced 100% mortality in all cases, thus indicating complete susceptibility of this strain to these insecticides. The adulticidal activity determined by topical application revealed that all five essential oils exerted a promising adulticidal efficacy against both laboratory and natural field strains of A. aegypti. Although the laboratory strain was slightly more susceptible to these essential oils than the natural field strain, no statistically significant difference was observed. Moreover, comparison of the adulticidal activity indicated that the performance of these essential oils against the two strains of A. aegypti was similar. The highest potential was established from caraway, followed by zedoary, celery, long pepper, and Chinese star anise, with an LC(50) in the laboratory strain of 5.44, 5.94, 5.96, 6.21, and 8.52 microg/mg female, respectively, and 5.54, 6.02, 6.14, 6.35, and 8.83 microg/mg female, respectively, in the field strain. These promising essential oils are, therefore, an alternative in developing and producing

  5. Resistance Status and Resistance Mechanisms in a Strain of Aedes aegypti (Diptera: Culicidae) From Puerto Rico.

    Science.gov (United States)

    Estep, Alden S; Sanscrainte, Neil D; Waits, Christy M; Louton, Jessica E; Becnel, James J

    2017-11-07

    Puerto Rico (PR) has a long history of vector-borne disease and insecticide-resistant Aedes aegypti (L.). Defining contributing mechanisms behind phenotypic resistance is critical for effective vector control intervention. However, previous studies from PR have each focused on only one mechanism of pyrethroid resistance. This study examines the contribution of P450-mediated enzymatic detoxification and sodium channel target site changes to the overall resistance phenotype of Ae. aegypti collected from San Juan, PR, in 2012. Screening of a panel of toxicants found broad resistance relative to the lab susceptible Orlando (ORL1952) strain. We identified significant resistance to representative Type I, Type II, and nonester pyrethroids, a sodium channel blocker, and a sodium channel blocking inhibitor, all of which interact with the sodium channel. Testing of fipronil, a chloride channel agonist, also showed low but significant levels of resistance. In contrast, the PR and ORL1952 strains were equally susceptible to chlorfenapyr, which has been suggested as an alternative public health insecticide. Molecular characterization of the strain indicated that two common sodium channel mutations were fixed in the population. Topical bioassay with piperonyl butoxide (PBO) indicated cytochrome P450-mediated detoxification accounts for approximately half of the resistance profile. Transcript expression screening of cytochrome P450s and glutathione-S-transferases identified the presence of overexpressed transcripts. This study of Puerto Rican Ae. aegypti with significant contributions from both genetic changes and enzymatic detoxification highlights the necessity of monitoring for resistance but also defining the multiple resistance mechanisms to inform effective mosquito control. Published by Oxford University Press on behalf of Entomological Society of America 2017. This work is written by US Government employees and is in the public domain in the US.

  6. Increasing multidrug resistance in Helicobacter pylori strains isolated from children and adults in Mexico.

    Science.gov (United States)

    Torres, J; Camorlinga-Ponce, M; Pérez-Pérez, G; Madrazo-De la Garza, A; Dehesa, M; González-Valencia, G; Muñoz, O

    2001-07-01

    The susceptibilities to three antimicrobials of 195 Helicobacter pylori strains isolated from Mexican patients is reported; 80% of the strains were resistant to metronidazole, 24% were resistant to clarithromycin, and 18% presented a transient resistance to amoxicillin. Resistance to two or more antimicrobials increased significantly from 1995 to 1997.

  7. Increasing Multidrug Resistance in Helicobacter pylori Strains Isolated from Children and Adults in Mexico

    OpenAIRE

    Torres, Javier; Camorlinga-Ponce, Margarita; Pérez-Pérez, Guillermo; Madrazo-De la Garza, Armando; Dehesa, Margarita; González-Valencia, Gerardo; Muñoz, Onofre

    2001-01-01

    The susceptibilities to three antimicrobials of 195 Helicobacter pylori strains isolated from Mexican patients is reported; 80% of the strains were resistant to metronidazole, 24% were resistant to clarithromycin, and 18% presented a transient resistance to amoxicillin. Resistance to two or more antimicrobials increased significantly from 1995 to 1997.

  8. Gene doctoring: a method for recombineering in laboratory and pathogenic Escherichia coli strains

    Science.gov (United States)

    2009-01-01

    Background Homologous recombination mediated by the λ-Red genes is a common method for making chromosomal modifications in Escherichia coli. Several protocols have been developed that differ in the mechanisms by which DNA, carrying regions homologous to the chromosome, are delivered into the cell. A common technique is to electroporate linear DNA fragments into cells. Alternatively, DNA fragments are generated in vivo by digestion of a donor plasmid with a nuclease that does not cleave the host genome. In both cases the λ-Red gene products recombine homologous regions carried on the linear DNA fragments with the chromosome. We have successfully used both techniques to generate chromosomal mutations in E. coli K-12 strains. However, we have had limited success with these λ-Red based recombination techniques in pathogenic E. coli strains, which has led us to develop an enhanced protocol for recombineering in such strains. Results Our goal was to develop a high-throughput recombineering system, primarily for the coupling of genes to epitope tags, which could also be used for deletion of genes in both pathogenic and K-12 E. coli strains. To that end we have designed a series of donor plasmids for use with the λ-Red recombination system, which when cleaved in vivo by the I-SceI meganuclease generate a discrete linear DNA fragment, allowing for C-terminal tagging of chromosomal genes with a 6 × His, 3 × FLAG, 4 × ProteinA or GFP tag or for the deletion of chromosomal regions. We have enhanced existing protocols and technologies by inclusion of a cassette conferring kanamycin resistance and, crucially, by including the sacB gene on the donor plasmid, so that all but true recombinants are counter-selected on kanamycin and sucrose containing media, thus eliminating the need for extensive screening. This method has the added advantage of limiting the exposure of cells to the potential damaging effects of the λ-Red system, which can lead to unwanted secondary

  9. Gene doctoring: a method for recombineering in laboratory and pathogenic Escherichia coli strains

    Directory of Open Access Journals (Sweden)

    Penn Charles W

    2009-12-01

    Full Text Available Abstract Background Homologous recombination mediated by the λ-Red genes is a common method for making chromosomal modifications in Escherichia coli. Several protocols have been developed that differ in the mechanisms by which DNA, carrying regions homologous to the chromosome, are delivered into the cell. A common technique is to electroporate linear DNA fragments into cells. Alternatively, DNA fragments are generated in vivo by digestion of a donor plasmid with a nuclease that does not cleave the host genome. In both cases the λ-Red gene products recombine homologous regions carried on the linear DNA fragments with the chromosome. We have successfully used both techniques to generate chromosomal mutations in E. coli K-12 strains. However, we have had limited success with these λ-Red based recombination techniques in pathogenic E. coli strains, which has led us to develop an enhanced protocol for recombineering in such strains. Results Our goal was to develop a high-throughput recombineering system, primarily for the coupling of genes to epitope tags, which could also be used for deletion of genes in both pathogenic and K-12 E. coli strains. To that end we have designed a series of donor plasmids for use with the λ-Red recombination system, which when cleaved in vivo by the I-SceI meganuclease generate a discrete linear DNA fragment, allowing for C-terminal tagging of chromosomal genes with a 6 × His, 3 × FLAG, 4 × ProteinA or GFP tag or for the deletion of chromosomal regions. We have enhanced existing protocols and technologies by inclusion of a cassette conferring kanamycin resistance and, crucially, by including the sacB gene on the donor plasmid, so that all but true recombinants are counter-selected on kanamycin and sucrose containing media, thus eliminating the need for extensive screening. This method has the added advantage of limiting the exposure of cells to the potential damaging effects of the λ-Red system, which can lead

  10. Phenotypic Resistance to Disinfectants and Antibiotics in Methicillin-Resistant Staphylococcus aureus Strains Isolated from Pigs.

    Science.gov (United States)

    Espigares, E; Moreno Roldan, E; Espigares, M; Abreu, R; Castro, B; Dib, A L; Arias, Á

    2017-06-01

    The aim of this research was to study the phenotypic resistances to disinfectants and antibiotics in strains of methicillin-resistant Staphylococcus aureus (MRSA) obtained from Canary black pigs. Analyses were performed on 54 strains of MRSA, isolated in Canary black pigs from the province of Tenerife (Spain); all of them carried the mecA gene. The strains were isolated by means of nasal swab samples of healthy pigs, collected under veterinarian supervision. Bactericidal activity of antiseptics and disinfectants was tested by means of the dilution-neutralization method. Susceptibility to the disinfectants glutaraldehyde, peracetic acid and silver nitrate was assessed, as well as to the antiseptics chlorhexidine, benzalkonium chloride and povidone iodine. Susceptibility to a wide array of antibiotics representing the main groups was determined by means of the disc diffusion method. All the strains demonstrated susceptibility to the disinfectants tested at the recommended concentration, and even to dilutions equal to or lesser than 1/16. The most effective antiseptic and disinfectant were, respectively, chlorhexidine and silver nitrate. With regard to the antibiotics, the strains proved to be multiresistant. All presented phenotypic resistance to the β-lactam antibiotics ampicillin, penicillin and cefoxitin, as well as to numerous aminoglycosides, tetracycline and trimethoprim-sulfamethoxazole. It was also observed that 61.1% of the strains were carriers of plasmids. Our results underline that in the strains such as MRSA, which show multiple resistances to antibiotics, the antiseptics and disinfectants show great efficacy. Moreover, as other authors also suggest, for the treatment and prevention of infections caused by MRSA, the use of β-lactam and aminoglycoside antibiotics may be less effective. © 2016 Blackwell Verlag GmbH.

  11. Mechanisms of methicillin resistance in Staphylococcus aureus and methods for laboratory detection.

    Science.gov (United States)

    Jorgensen, J H

    1991-01-01

    Three distinctly different mechanisms of methicillin resistance have been described in Staphylococcus aureus. The best-documented and probably most important mechanism is production of a unique, low affinity penicillin-binding protein, PBP 2a. Strains possessing PBP 2a are resistant to methicillin, oxacillin, and probably all other currently available beta-lactam antibiotics. Two additional mechanisms of reduced susceptibility to methicillin have been described. Borderline resistance (BORSA) to the semi-synthetic penicillins has been attributed to the hyperproduction of normal staphylococcal beta-lactamase. A third mechanism has recently been advanced that describes an intermediate level of resistance to methicillin due to production of modified, normal PBPs with reduced affinity for beta-lactams (MODSA). Little is known regarding the prevalence or clinical significance of the BORSA and MODSA strains. The most reliable in vitro susceptibility test methods for detecting MRSA (strains possessing PBP 2a) include the microdilution minimum inhibitory concentration (MIC) test (with 2% NaCl supplemented broth), the oxacillin agar screen plate test (incorporating 6 micrograms/ml oxacillin in 4% NaCl supplemented agar), and the National Committee for Clinical Laboratory Standards (NCCLS) disk diffusion test with oxacillin. All three methods use direct inoculum preparation and incubation of tests at 35 degrees C for a full 24 hours.

  12. Resistance to antibiotics in Lacid acid bacteria - strain Lactococcus

    Directory of Open Access Journals (Sweden)

    Filipić Brankica

    2015-01-01

    Full Text Available Lactic acid bacteria (LAB are widely used in the food industry, especially in the production of fermented dairy products and meat. The most studied species among Lis Lactococcus lactis. L. lactis strains are of great importance in the production of fermented dairy products such as yogurt, butter, fresh cheese and some kind of semi-hard cheese. Although L. lactis acquired the „Generally Regarded As Safe“ (GRAS status, many investigations indicated that lactococci may act as reservoirs of antibiotic resistance genes, which could be transferred to other bacterial species in human gastrointestinal tract includ­ing pathogens. The genome analysis of L. lactis indicated the presence of at least 40 putative drug transporter genes, and only four multidrug resistance (MDR transporters are functionally characterized: LmrA, LmrP, LmrCD i CmbT. LmrA is the first described MDR transporter in prokaryotes. LmrCD is responsible for resistance to cholate, which is an integral part of human bile and LmrCD is important for intestinal survival of lactococci that are used as probiotics. Secondary multidrug transporter LmrP confers resistance to lincosamides, macrolides, streptogramins and tetracyclines. CmbT protein has an effect on the host cell resistance to lincomycin, sulfadiazine, streptomycin, rifampicin, puromycin and sulfametox­azole. Since the food chain is an important way of transmitting resistance genes in human and animal population, it is of great importance to study the mechanisms of resistance in lactococci and other LAB, intended for the food industry. [Projekat Ministarstva nauke Republike Srbije, br. 173019: Izučavanje gena i molekularnih mehanizama u osnovi probiotičke aktivnosti bakterija mlečne kiseline izolovanih sa područja Zapadnog Balkana

  13. Standard guide for installing bonded resistance strain gages

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    1993-01-01

    1.1 This guide provides guidelines for installing bonded resistance strain gages. It is not intended to be used for bulk or diffused semiconductor gages. This document pertains only to adhesively bonded strain gages. 1.2 The values stated in inch-pound units are to be regarded as standard. The values given in parentheses are mathematical conversions to SI units that are provided for information only and are not considered standard. 1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.

  14. Caloric Restriction in Lean and Obese Strains of Laboratory ...

    Science.gov (United States)

    NEW FINDINGS: What is the central question of this study? How do lean and obese rats respond physiologically to caloric restriction? What is the main finding and its importance? Obese rats show marked benefits compared with lean animals. Reduced body fat is associated with improved longevity with caloric restriction (CR) in rodents. Little is known regarding effects of CR in genetically lean versus obese strains. Long-Evans (LE) and Brown Norway (BN) rats make an ideal comparison for a CR study because the percentage body fat of young adult LE rats is double that of BN rats. Male LE and BN rats were either fed ad libitum (AL) or were caloricallyrestricted to 80 or 90% of their AL weight. The percentages of fat, lean and fluid mass were measured non-invasively at 2- to 4-week intervals. Metabolic rate and respiratory quotient were measured after 3, 6, 9 and 12 months of CR. Overall health was scored monthly. The percentage of fat of the LE strain decreased with CR, whereas the percentage of fat of the BN strain remained above the AL group for several months. The percentage of lean mass increased above the AL for both strains subjected to CR. The percentage offluid was unaffected by CR. The average metabolic rate over 22 h of the BN rats subjected to CR was reduced, whereas that of LE rats was increased slightly above the AL group. The respiratory quotient of BN rats wasdecreased with CR. Overall health of the CR LE group was significantly improved compared with t

  15. Analysis of differentially expressed genes related to resistance in spinosad- and neonicotinoid-resistant Musca domestica L. (Diptera: Muscidae) strains

    DEFF Research Database (Denmark)

    Castberg, Dorte Heidi Højland; Kristensen, Michael

    2017-01-01

    interesting in terms of neonicotinoid resistance, while cyp4d9 was overexpressed in 791spin compared to spinosad-susceptible strains. GSTs, ESTs and UGTs were mostly overexpressed, but not to the same degree as P450s. We present a comprehensive and comparative picture of gene expression in three housefly......Background The housefly is a global pest that has developed resistance to most insecticides applied against it. Resistance of the spinosad-resistant strain 791spin and the neonicotinoid-resistant 766b strain is believed to be due to metabolism. We investigate differentially expressed genes...... strains differing significantly in their response to insecticides. High differential expression of P450s and genes coding for cuticle protein indicates a combination of factors involved in metabolic neonicotinoid and spinosad resistance. Conclusion Resistance in these strains is apparently not linked...

  16. Mechanisms of resistance in nontyphoidal Salmonella enterica strains exhibiting a nonclassical quinolone resistance phenotype.

    Science.gov (United States)

    Gunell, Marianne; Webber, Mark A; Kotilainen, Pirkko; Lilly, Andrew J; Caddick, Jonathan M; Jalava, Jari; Huovinen, Pentti; Siitonen, Anja; Hakanen, Antti J; Piddock, Laura J V

    2009-09-01

    Nontyphoidal Salmonella enterica strains with a nonclassical quinolone resistance phenotype were isolated from patients returning from Thailand or Malaysia to Finland. A total of 10 isolates of seven serovars were studied in detail, all of which had reduced susceptibility (MIC > or = 0.125 microg/ml) to ciprofloxacin but were either susceptible or showed only low-level resistance (MIC resistance-determining regions (QRDR) of gyrA, gyrB, parC, and parE by PCR and denaturing high-pressure liquid chromatography and the amplification of plasmid-mediated quinolone resistance (PMQR) genes qnrA, qnrB, qnrS, qnrD, aac(6')-Ib-cr, and qepA by PCR. PMQR was confirmed by plasmid analysis, Southern hybridization, and plasmid transfer. No mutations in the QRDRs of gyrA, gyrB, parC, or parE were detected with the exception of a Thr57-Ser substitution within ParC seen in all but the S. enterica serovar Typhimurium strains. The qnrA and qnrS genes were the only PMQR determinants detected. Plasmids carrying qnr alleles were transferable in vitro, and the resistance phenotype was reproducible in Escherichia coli DH5alpha transformants. These data demonstrate the emergence of a highly mobile qnr genotype that, in the absence of mutation within topoisomerase genes, confers the nontypical quinolone resistance phenotype in S. enterica isolates. The qnr resistance mechanism enables bacteria to survive elevated quinolone concentrations, and therefore, strains carrying qnr alleles may be able to expand during fluoroquinolone treatment. This is of concern since nonclassical quinolone resistance is plasmid mediated and therefore mobilizable.

  17. Molecular Detection of Inducible Clindamycin Resistance among Staphylococcal Strains Isolated from Hospital Patients

    Directory of Open Access Journals (Sweden)

    Shadiyeh Abdollahi

    2013-04-01

    Full Text Available Background & Objectives: Macrolide, lincosamide and streptogramin B (MLSB antimicrobial agents are used in the treatment of staphylococcal infections. They prevent the microbial protein synthesis system through binding to 23 S rRNA. The aim of this study was to apply molecular methods to detect inducible clindamycin resistance genes among staphylococcal strains isolated from clinical specimens.   Methods : Two hundred staphylococcus strains were isolated from nose and throat swabs of patients in Toohid and Besat hospitals in Sanandaj . Antimicrobial susceptibilities of isolates were determined using disc diffusion method, agar screen test and D-Test. A multiplex PCR was performed using primers specific for erm (A, B, C, TR genes.   Results: Out of 200 isolates, 18.5 % were MRSA and 32% were MRCNS (methicillin resistant coagulase negative staphylococci. Of 80 erythromycin resistant isolates, 48 were coagulase negative and 32 were S. aureus. Among the 48 coagulase negative staphylococci (CONS isolates, 11.63% expressed the MLSB-inducible phenotypes. Using PCR, the frequency of different genes in the collection of isolates were as follows: ermA 5.41 % , erm B 5.41 % , and erm C 3.13%. The ermTR gene was negative in all isolates. Among the 32 S. aureus isolates, 9.38% expressed the MLSB-nducible phenotype. Using PCR, these isolates harbored erm A (2.22%, ermB (2.22%, ermC (2.22% and ermTR (2.22% .   Conclusion: This is the first study to show the rate of inducible clindamycin clinical isolates of staphylococci harboring erm genes in Sananadaj. It also demonstrated the frequency of erm genes was higher among CONS isolates than S. aureus. This data suggested the transfer of resistance gene from nonpathogenic to pathogenic strains is likely to happen. Therefore, screening and control of these resistance genes is recommended at clinical laboratories.

  18. Comparisons of transcriptional profiles of gut genes between cry1Ab-resistant and susceptible strains of Ostrinia nubilalis revealed genes possibly related to the adaptation of resistant larvae to transgenic cry1Ab corn

    Science.gov (United States)

    European corn borer (Ostrinia nubilalis) gut 2,895 unique genes expressions were quantified and compared between a laboratory-selected Cry1Ab-resistant (R) strain and a susceptible (S) strain after fed transgenic corn (MON810) leaves expressing Cry1Ab by microarray. A total of 398 gut genes were di...

  19. Genetic basis for nitrate resistance in Desulfovibrio strains

    Directory of Open Access Journals (Sweden)

    Hannah eKorte

    2014-04-01

    Full Text Available Nitrate is an inhibitor of sulfate-reducing bacteria (SRB. In petroleum production sites, amendments of nitrate and nitrite are used to prevent SRB production of sulfide that causes souring of oil wells. A better understanding of nitrate stress responses in the model SRB, Desulfovibrio vulgaris Hildenborough and Desulfovibrio alaskensis G20, will strengthen predictions of environmental outcomes. Nitrate inhibition of SRB has historically been considered to result from the generation of small amounts of nitrite, to which SRB are quite sensitive. Here we explored the possibility that nitrate might inhibit SRB by a mechanism other than through nitrite inhibition. We found that nitrate-stressed D. vulgaris cultures grown in lactate-sulfate conditions eventually grew in the presence of high concentrations of nitrate, and their resistance continued through several subcultures. Nitrate consumption was not detected over the course of the experiment, suggesting adaptation to nitrate. With high-throughput genetic approaches employing TnLE-seq for D. vulgaris and a pooled mutant library of D. alaskensis, we determined the fitness of many transposon mutants of both organisms in nitrate stress conditions. We found that several mutants, including homologs present in both strains, had a greatly increased ability to grow in the presence of nitrate but not nitrite. The mutated genes conferring nitrate resistance included the gene encoding the putative Rex transcriptional regulator (DVU0916/Dde_2702, as well as a cluster of genes (DVU0251-DVU0245/Dde_0597-Dde_0605 that is poorly annotated. Follow-up studies with individual D. vulgaris transposon and deletion mutants confirmed high-throughput results. We conclude that, in D. vulgaris and D. alaskensis, nitrate resistance in wild-type cultures is likely conferred by spontaneous mutations. Furthermore, the mechanisms that confer nitrate resistance may be different from those that confer nitrite resistance.

  20. The resistance to antibiotics of strains of Staphylococcus aureus isolated in Poland*

    Science.gov (United States)

    Jeljaszewicz, J.; Hawiger, J.

    1966-01-01

    The increasing number of antibiotic-resistant strains of micro-organisms is posing serious problems. A nation-wide survey has therefore been carried out in Poland to determine the resistance of strains of Staphylococcus aureus from different sources to eight antibiotics; in all, some 31 000 strains were examined. In general, the most resistant strains from humans were derived from faeces, urine and blood, and the least resistant from bile and pus. Food yielded strains of even lower resistance. Strains from hospital material were, in general, considerably more resistant than those from non-hospital material. The only exception was in resistance to neomycin; the strains most resistant to this antibiotic were obtained from bile and throat, and the least resistant from urine and cerebrospinal fluid; moreover, non-hospital strains were more resistant than hospital ones. On the average, the proportions of strains resistant to the eight antibiotics were: penicillin, 84.0%; streptomycin, 69.5%; tetracycline, 60.1%; chlortetracycline, 56.9%; oxytetracycline, 56.7%; neomycin, 56.2%; chloramphenicol, 48.6%; erythromycin, 47.4%. PMID:5297006

  1. Efficacy of an insecticide paint against insecticide-susceptible and resistant mosquitoes - Part 1: Laboratory evaluation

    Directory of Open Access Journals (Sweden)

    Carnevale Pierre

    2010-11-01

    Full Text Available Abstract Background The main malaria vector Anopheles gambiae and the urban pest nuisance Culex quinquefasciatus are increasingly resistant to pyrethroids in many African countries. There is a need for new products and strategies. Insecticide paint Inesfly 5A IGR™, containing two organophosphates (OPs, chlorpyrifos and diazinon, and insect growth regulator (IGR, pyriproxyfen, was tested under laboratory conditions for 12 months following WHOPES Phase I procedures. Methods Mosquitoes used were laboratory strains of Cx. quinquefasciatus susceptible and resistant to OPs. The paint was applied at two different doses (1 kg/6 m2 and 1 kg/12 m2 on different commonly used surfaces: porous (cement and stucco and non-porous (softwood and hard plastic. Insecticide efficacy was studied in terms of delayed mortality using 30-minute WHO bioassay cones. IGR efficacy on fecundity, fertility and larval development was studied on OP-resistant females exposed for 30 minutes to cement treated and control surfaces. Results After treatment, delayed mortality was high (87-100% even against OP-resistant females on all surfaces except cement treated at 1 kg/12 m2. Remarkably, one year after treatment delayed mortality was 93-100% against OP-resistant females on non-porous surfaces at both doses. On cement, death rates were low 12 months after treatment regardless of the dose and the resistance status. Fecundity, fertility and adult emergence were reduced after treatment even at the lower dose (p -3. A reduction in fecundity was still observed nine months after treatment at both doses (p -3 and adult emergence was reduced at the higher dose (p -3. Conclusions High mortality rates were observed against laboratory strains of the pest mosquito Cx. quinquefasciatus susceptible and resistant to insecticides. Long-term killing remained equally important on non-porous surfaces regardless the resistance status for over 12 months. The paint's effect on fecundity, fertility and

  2. Identification and Characterization of Vancomycin-resistant Enterococcus species Frequently Isolated from Laboratory Mice

    Science.gov (United States)

    Yamanaka, Hitoki; Takagi, Toshikazu; Ohsawa, Makiko; Yamamoto, Naoto; Kubo, Noriaki; Takemoto, Takahira; Sasano, Shoko; Masuyama, Ritsuko; Ohsawa, Kazutaka

    2014-01-01

    To determine the prevalence of drug resistant bacteria colonizing laboratory mice, we isolated and characterized vancomycin-resistant Enterococcus species (VRE) from commercially available mice. A total of 24 VRE isolates were obtained from 19 of 21 mouse strains supplied by 4 commercial breeding companies. Of these, 19 isolates of E. gallinarum and 5 isolates of E. casseliflavus possessing the vanC1 and vanC2/3 genes intrinsically, exhibited intermediate resistance to vancomycin respectively. In addition, these isolates also exhibited diverse resistant patterns to erythromycin, tetracycline, and ciprofloxacin, whereas the use of antibiotics had not been undertaken in mouse strains tested in this study. Although 6 virulence-associated genes (ace, asa, cylA, efaA, esp, and gelE) and secretion of gelatinase and hemolysin were not detected in all isolates, 23 of 24 isolates including the isolates of E. casselifalvus secreted ATP into culture supernatants. Since secretion of ATP by bacteria resident in the intestinal tract modulates the local immune responses, the prevalence of ATP-secreting VRE in mice therefore needs to be considered in animal experiments that alter the gut microflora by use of antibiotics. PMID:25077759

  3. Bacteriocin-like inhibitory activities of seven Lactobacillus delbrueckii subsp. bulgaricus strains against antibiotic susceptible and resistant Helicobacter pylori strains.

    Science.gov (United States)

    Boyanova, L; Gergova, G; Markovska, R; Yordanov, D; Mitov, I

    2017-12-01

    The aim of the study was to detect anti-Helicobacter pylori activity of seven Lactobacillus delbrueckii subsp. bulgaricus (GLB) strains by four cell-free supernatant (CFS) types. Activity of non-neutralized and non-heat-treated (CFSs1), non-neutralized and heat-treated (CFSs2), pH neutralized, catalase-treated and non-heat-treated (CFSs3), or neutralized, catalase- and heat-treated (CFSs4) CFSs against 18 H. pylori strains (11 of which with antibiotic resistance) was evaluated. All GLB strains produced bacteriocin-like inhibitory substances (BLISs), the neutralized CFSs of two GLB strains inhibited >81% of test strains and those of four GLB strains were active against >71% of antibiotic resistant strains. Two H. pylori strains were BLIS resistant. The heating did not reduce the CFS activity. Briefly, all GLB strains evaluated produced heat-stable BLISs, although GLB and H. pylori strain susceptibility patterns exhibited differences. Bacteriocin-like inhibitory substance activity can be an advantage for the probiotic choice for H. pylori infection control. In this study, anti-Helicobacter pylori activity of seven Lactobacillus delbrueckii subsp. bulgaricus (GLB) strains was evaluated by four cell-free supernatant (CFS) types. The GLB strains produced heat-stable bacteriocin-like inhibitory substances (BLISs) with a strong anti-H. pylori activity and some neutralized, catalase- and heat-treated CFSs inhibited >83% of the test strains. Bacteriocin-like inhibitory substance production of GLB strains can render them valuable probiotics in the control of H. pylori infection. © 2017 The Society for Applied Microbiology.

  4. Similar genetic basis of resistance to Bt toxin Cry1Ac in Boll-selected and diet-selected strains of pink bollworm.

    Directory of Open Access Journals (Sweden)

    Jeffrey A Fabrick

    Full Text Available Genetically engineered cotton and corn plants producing insecticidal Bacillus thuringiensis (Bt toxins kill some key insect pests. Yet, evolution of resistance by pests threatens long-term insect control by these transgenic Bt crops. We compared the genetic basis of resistance to Bt toxin Cry1Ac in two independently derived, laboratory-selected strains of a major cotton pest, the pink bollworm (Pectinophora gossypiella [Saunders]. The Arizona pooled resistant strain (AZP-R was started with pink bollworm from 10 field populations and selected with Cry1Ac in diet. The Bt4R resistant strain was started with a long-term susceptible laboratory strain and selected first with Bt cotton bolls and later with Cry1Ac in diet. Previous work showed that AZP-R had three recessive mutations (r1, r2, and r3 in the pink bollworm cadherin gene (PgCad1 linked with resistance to Cry1Ac and Bt cotton producing Cry1Ac. Here we report that inheritance of resistance to a diagnostic concentration of Cry1Ac was recessive in Bt4R. In interstrain complementation tests for allelism, F(1 progeny from crosses between AZP-R and Bt4R were resistant to Cry1Ac, indicating a shared resistance locus in the two strains. Molecular analysis of the Bt4R cadherin gene identified a novel 15-bp deletion (r4 predicted to cause the loss of five amino acids upstream of the Cry1Ac-binding region of the cadherin protein. Four recessive mutations in PgCad1 are now implicated in resistance in five different strains, showing that mutations in cadherin are the primary mechanism of resistance to Cry1Ac in laboratory-selected strains of pink bollworm from Arizona.

  5. Endosulfan Resistance Profile of Soil Bacteria and Potential Application of Resistant Strains in Bioremediation

    Directory of Open Access Journals (Sweden)

    Chandini P.K.

    2014-05-01

    Full Text Available In the present study, bacterial strains were isolated from the soils of Wayanad District, Kerala, India and the isolates were tested for their tolerance to endosulfan and potential in bioremediation technology. Pesticide contamination in the soils, soil physico-chemical characteristics and socio-economic impacts of pesticide application were also analyzed. 28 pesticide compounds in the soil samples were analyzed and the results revealed that there was no pesticide residues in the soils. As per the survey conducted the pesticide application is very high in the study area and the level of awareness among the farmers was very poor regarding the method of application and its socio-economic and ecological impacts. A total of 9 bacterial strains were isolated with 50μg/ml of endosulfan in the isolating media and the results showed that most of the bacterial strains were highly resistance to endosulfan. Out of the 9 strains isolated 6 were highly resistant to endosulfan (500- 700μg/ml and the other 3 isolates showed the resistance of 250-500μg/ml. From the studied isolate, isolate 9 demonstrating prolific growth and high resistance was selected to check their capability to degrade endosulfan over time. Identification of the selected strain reveals that it belongs to the genus Bacillus. Results of endosulfan removal studies showed that with increase in time, the biomass of the bacterial strains increased. The complete disappearance of endosulfan from the spiked and inoculated broth during the first day of incubation (24 hour interval was observed. While the control flask showed the presence of endosulfan during the experimental period. Pesticide resistant bacteria are widely distributed in the soils of selected study area and the tolerance varied between bacteria even though they were isolated from the soils of the same area. The selected Bacillus species carry the ability to degrade endosulfan at accelerated rates and it could be useful in framing a

  6. Fatal laboratory-acquired infection with an attenuated Yersinia pestis Strain--Chicago, Illinois, 2009.

    Science.gov (United States)

    2011-02-25

    On September 18, 2009, the Chicago Department of Public Health (CDPH) was notified by a local hospital of a suspected case of fatal laboratory-acquired infection with Yersinia pestis, the causative agent of plague. The patient, a researcher in a university laboratory, had been working along with other members of the laboratory group with a pigmentation-negative (pgm-) attenuated Y. pestis strain (KIM D27). The strain had not been known to have caused laboratory-acquired infections or human fatalities. Other researchers in a separate university laboratory facility in the same building had contact with a virulent Y. pestis strain (CO92) that is considered a select biologic agent; however, the pgm- attenuated KIM D27 is excluded from the National Select Agent Registry. The university, CDPH, the Illinois Department of Public Health (IDPH), and CDC conducted an investigation to ascertain the cause of death. This report summarizes the results of that investigation, which determined that the cause of death likely was an unrecognized occupational exposure (route unknown) to Y. pestis, leading to septic shock. Y. pestis was isolated from premortem blood cultures. Polymerase chain reaction (PCR) identified the clinical isolate as a pgm- strain of Y. pestis. Postmortem examination revealed no evidence of pneumonic plague. A postmortem diagnosis of hereditary hemochromatosis was made on the basis of histopathologic, laboratory, and genetic testing. One possible explanation for the unexpected fatal outcome in this patient is that hemochromatosis-induced iron overload might have provided the infecting KIM D27 strain, which is attenuated as a result of defects in its ability to acquire iron, with sufficient iron to overcome its iron-acquisition defects and become virulent. Researchers should adhere to recommended biosafety practices when handling any live bacterial cultures, even attenuated strains, and institutional biosafety committees should implement and maintain effective

  7. Emergence of macrolide-resistant Campylobacter strains in chicken meat in Poland and the resistance mechanisms involved.

    Science.gov (United States)

    Rożynek, Elżbieta; Maćkiw, Elżbieta; Kamińska, Wanda; Tomczuk, Katarzyna; Antos-Bielska, Małgorzata; Dzierżanowska-Fangrat, Katarzyna; Korsak, Dorota

    2013-07-01

    In this study, we investigated the molecular mechanisms involved in erythromycin resistance in the first resistant Campylobacter strains isolated from chicken meat in Poland, and analyzed their genetic relatedness. A total of 297 samples of raw chicken meat and giblets from retail trade in the Warsaw area collected between 2006 and 2009 were examined. Among 211 Campylobacter strains (52 C. jejuni and 159 C. coli), 10 C. coli isolates (4.7%) were resistant to erythromycin. All the C. jejuni strains were susceptible. Among the high-level macrolide-resistant isolates, two different point mutations within the domain V of the 23S rRNA gene were observed. Eight of the strains had adenine→guanine transitions at position 2075, two other isolates at position 2074. Sequence analysis of ribosomal proteins L4 (rplD) and L22 (rplV) indicated that ribosomal protein modifications did not contribute to macrolide resistance. A mutation in the inverted repeat in the cmeR and cmeABC intergenic region was found in a single resistant strain. The genetic relatedness of Campylobacter isolates showed that two resistant strains obtained from the same production plant in a 2-month interval were genetically identical. The risk of transmission of resistant strains via the food chain highlights the need for constant monitoring of resistance in Campylobacter isolates of human and animal hosts.

  8. Epidemiology, Clinical Presentation, Laboratory Diagnosis, Antimicrobial Resistance, and Antimicrobial Management of Invasive Salmonella Infections

    Science.gov (United States)

    Sjölund-Karlsson, Maria; Gordon, Melita A.; Parry, Christopher M.

    2015-01-01

    SUMMARY Salmonella enterica infections are common causes of bloodstream infection in low-resource areas, where they may be difficult to distinguish from other febrile illnesses and may be associated with a high case fatality ratio. Microbiologic culture of blood or bone marrow remains the mainstay of laboratory diagnosis. Antimicrobial resistance has emerged in Salmonella enterica, initially to the traditional first-line drugs chloramphenicol, ampicillin, and trimethoprim-sulfamethoxazole. Decreased fluoroquinolone susceptibility and then fluoroquinolone resistance have developed in association with chromosomal mutations in the quinolone resistance-determining region of genes encoding DNA gyrase and topoisomerase IV and also by plasmid-mediated resistance mechanisms. Resistance to extended-spectrum cephalosporins has occurred more often in nontyphoidal than in typhoidal Salmonella strains. Azithromycin is effective for the management of uncomplicated typhoid fever and may serve as an alternative oral drug in areas where fluoroquinolone resistance is common. In 2013, CLSI lowered the ciprofloxacin susceptibility breakpoints to account for accumulating clinical, microbiologic, and pharmacokinetic-pharmacodynamic data suggesting that revision was needed for contemporary invasive Salmonella infections. Newly established CLSI guidelines for azithromycin and Salmonella enterica serovar Typhi were published in CLSI document M100 in 2015. PMID:26180063

  9. Laboratory-Cultured Strains of the Sea Anemone Exaiptasia Reveal Distinct Bacterial Communities

    KAUST Repository

    Herrera Sarrias, Marcela

    2017-05-02

    Exaiptasia is a laboratory sea anemone model system for stony corals. Two clonal strains are commonly used, referred to as H2 and CC7, that originate from two genetically distinct lineages and that differ in their Symbiodinium specificity. However, little is known about their other microbial associations. Here, we examined and compared the taxonomic composition of the bacterial assemblages of these two symbiotic Exaiptasia strains, both of which have been cultured in the laboratory long-term under identical conditions. We found distinct bacterial microbiota for each strain, indicating the presence of host-specific microbial consortia. Putative differences in the bacterial functional profiles (i.e., enrichment and depletion of various metabolic processes) based on taxonomic inference were also detected, further suggesting functional differences of the microbiomes associated with these lineages. Our study contributes to the current knowledge of the Exaiptasia holobiont by comparing the bacterial diversity of two commonly used strains as models for coral research.

  10. Growth temperature exerts differential physiological and transcriptional responses in laboratory and wine strains of Saccharomyces cerevisiae.

    Science.gov (United States)

    Pizarro, Francisco J; Jewett, Michael C; Nielsen, Jens; Agosin, Eduardo

    2008-10-01

    Laboratory strains of Saccharomyces cerevisiae have been widely used as a model for studying eukaryotic cells and mapping the molecular mechanisms of many different human diseases. Industrial wine yeasts, on the other hand, have been selected on the basis of their adaptation to stringent environmental conditions and the organoleptic properties that they confer to wine. Here, we used a two-factor design to study the responses of a standard laboratory strain, CEN.PK113-7D, and an industrial wine yeast strain, EC1118, to growth temperatures of 15 degrees C and 30 degrees C in nitrogen-limited, anaerobic, steady-state chemostat cultures. Physiological characterization revealed that the growth temperature strongly impacted the biomass yield of both strains. Moreover, we found that the wine yeast was better adapted to mobilizing resources for biomass production and that the laboratory yeast exhibited higher fermentation rates. To elucidate mechanistic differences controlling the growth temperature response and underlying adaptive mechanisms between the strains, DNA microarrays and targeted metabolome analysis were used. We identified 1,007 temperature-dependent genes and 473 strain-dependent genes. The transcriptional response was used to identify highly correlated gene expression subnetworks within yeast metabolism. We showed that temperature differences most strongly affect nitrogen metabolism and the heat shock response. A lack of stress response element-mediated gene induction, coupled with reduced trehalose levels, indicated that there was a decreased general stress response at 15 degrees C compared to that at 30 degrees C. Differential responses among strains were centered on sugar uptake, nitrogen metabolism, and expression of genes related to organoleptic properties. Our study provides global insight into how growth temperature affects differential physiological and transcriptional responses in laboratory and wine strains of S. cerevisiae.

  11. Candidacidal Activity of a Novel Killer Toxin from Wickerhamomyces anomalus against Fluconazole-Susceptible and -Resistant Strains

    Directory of Open Access Journals (Sweden)

    Laura Giovati

    2018-02-01

    Full Text Available The isolation and characterization from the sand fly Phlebotomus perniciosus of a Wickerhamomyces anomalus yeast strain (Wa1F1 displaying the killer phenotype was recently reported. In the present work, the killer toxin (KT produced by Wa1F1 was purified and characterized, and its antimicrobial activity in vitro was investigated against fluconazole- susceptible and -resistant clinical isolates and laboratory strains of Candida albicans and C. glabrata displaying known mutations. Wa1F1-KT showed a differential killing ability against different mutant strains of the same species. The results may be useful for the design of therapeutic molecules based on Wa1F1-KT and the study of yeast resistance mechanisms.

  12. Genome Sequences of Two Copper-Resistant Escherichia coli Strains Isolated from Copper-Fed Pigs

    DEFF Research Database (Denmark)

    Lüthje, Freja L.; Hasman, Henrik; Aarestrup, Frank Møller

    2014-01-01

    The draft genome sequences of two copper-resistant Escherichia coli strains were determined. These had been isolated from copper-fed pigs and contained additional putative operons conferring copper and other metal and metalloid resistances.......The draft genome sequences of two copper-resistant Escherichia coli strains were determined. These had been isolated from copper-fed pigs and contained additional putative operons conferring copper and other metal and metalloid resistances....

  13. ANTIBIOTIC RESISTANCE IN ENTEROBACTERIACEAE STRAINS ISOLATED FROM CHICKEN AND MILK SAMPLES

    Directory of Open Access Journals (Sweden)

    Lukáš Hleba

    2015-02-01

    Full Text Available Antibiotic resistance and identification of strains in Enterobacteriaceae genera isolated from milk, milk products and rectal swabs of chicken was examined in this experiment. After samples collection cultivation and identification of bacterial strain was done. MALDI TOF MS Biotyper for identification of Enterobacteriaceae strains was used. For susceptibility testing disc diffusion methodology was used according by EUCAST. Results showed high level of ampicillin resistance in isolates from milk and milk samples. The highest streptomycin resistance was detected in isolates from rectal swabs of chicken. After identification, we determined that S. enterica ser. Typhimurium, which was isolated from rectal swabs of chicken showed the most multi-resistance from all identificated strains of Enterobacteriaceae. The most isolates bacterial strain was E. coli, which showed resistance against four antibiotics from rectal swabs of chicken. Also our results showed that the higher resistance level is in rectal swabs of chicken like in milk samples.

  14. Assessment of Plasmodium falciparum resistance to ferroquine (SSR97193 in field isolates and in W2 strain under pressure

    Directory of Open Access Journals (Sweden)

    Pradines Bruno

    2006-02-01

    Full Text Available Abstract Background Ferroquine (FQ, or SSR97193, is a novel antimalarial drug currently in phase I clinical trials. FQ is a unique organometallic compound designed to overcome the chloroquine (CQ resistance problem. FQ revealed to be equally active on CQ-sensitive and CQ-resistant Plasmodium falciparum laboratory strains and field isolates. FQ is also curative on rodent malaria parasites. As FQ will be tested in patients, the potential for resistance to this drug was evaluated. Methods The relationship between CQ-resistant transporter gene genotype and susceptibility to FQ were studied in 33 Cambodian P. falciparum field isolates previously studied for their in vitro response to CQ. In parallel, the ability of the CQ-resistant strain W2, to become resistant to FQ under drug pressure was assessed. Results The IC50 values for FQ in field isolates were found to be unrelated to mutations occurring in the P. falciparum chloroquine resistance transporter (PfCRT or to the level of expression of the corresponding mRNA. In vitro, under a drug pressure of 100 nM of FQ, transient survival was observed in only one of two experiments. Conclusion Field isolates studies and experimental drug pressure experiments showed that FQ overcomes CQ resistance, which reinforces the potential of this compound as a new antimalarial drug.

  15. Novel Genes Related to Ceftriaxone Resistance Found among Ceftriaxone-Resistant Neisseria gonorrhoeae Strains Selected In Vitro.

    Science.gov (United States)

    Gong, Zijian; Lai, Wei; Liu, Min; Hua, Zhengshuang; Sun, Yayin; Xu, Qingfang; Xia, Yue; Zhao, Yue; Xie, Xiaoyuan

    2016-04-01

    The emergence of ceftriaxone-resistantNeisseria gonorrhoeaeis currently a global public health concern. However, the mechanism of ceftriaxone resistance is not yet fully understood. To investigate the potential genes related to ceftriaxone resistance inNeisseria gonorrhoeae, we subcultured six gonococcal strains with increasing concentrations of ceftriaxone and isolated the strains that became resistant. After analyzing several frequently reported genes involved in ceftriaxone resistance, we found only a single mutation inpenA(A501V). However, differential analysis of the genomes and transcriptomes between pre- and postselection strains revealed many other mutated genes as well as up- and downregulated genes. Transformation of the mutatedpenAgene into nonresistant strains increased the MIC between 2.0- and 5.3-fold, and transformation of mutatedftsXincreased the MIC between 3.3- and 13.3-fold. Genes encoding the ABC transporters FarB, Tfq, Hfq, and ExbB were overexpressed, whilepilM,pilN, andpilQwere downregulated. Furthermore, the resistant strain developed cross-resistance to penicillin and cefuroxime, had an increased biochemical metabolic rate, and presented fitness defects such as prolonged growth time and downregulated PilMNQ. In conclusion, antimicrobial pressure could result in the emergence of ceftriaxone resistance, and the evolution of resistance ofNeisseria gonorrhoeaeto ceftriaxone is a complicated process at both the pretranscriptional and posttranscriptional levels, involving several resistance mechanisms of increased efflux and decreased entry. Copyright © 2016, American Society for Microbiology. All Rights Reserved.

  16. Efficacy of an insecticide paint against insecticide-susceptible and resistant mosquitoes - Part 1: Laboratory evaluation

    Science.gov (United States)

    2010-01-01

    Background The main malaria vector Anopheles gambiae and the urban pest nuisance Culex quinquefasciatus are increasingly resistant to pyrethroids in many African countries. There is a need for new products and strategies. Insecticide paint Inesfly 5A IGR™, containing two organophosphates (OPs), chlorpyrifos and diazinon, and insect growth regulator (IGR), pyriproxyfen, was tested under laboratory conditions for 12 months following WHOPES Phase I procedures. Methods Mosquitoes used were laboratory strains of Cx. quinquefasciatus susceptible and resistant to OPs. The paint was applied at two different doses (1 kg/6 m2 and 1 kg/12 m2) on different commonly used surfaces: porous (cement and stucco) and non-porous (softwood and hard plastic). Insecticide efficacy was studied in terms of delayed mortality using 30-minute WHO bioassay cones. IGR efficacy on fecundity, fertility and larval development was studied on OP-resistant females exposed for 30 minutes to cement treated and control surfaces. Results After treatment, delayed mortality was high (87-100%) even against OP-resistant females on all surfaces except cement treated at 1 kg/12 m2. Remarkably, one year after treatment delayed mortality was 93-100% against OP-resistant females on non-porous surfaces at both doses. On cement, death rates were low 12 months after treatment regardless of the dose and the resistance status. Fecundity, fertility and adult emergence were reduced after treatment even at the lower dose (p paint's effect on fecundity, fertility and adult emergence may continue to provide an additional angle of attack in reducing overall population densities when the lethal effect of OPs diminishes over time. Some options on how to deal with porous materials are given. Implications in vector control are discussed. PMID:21108819

  17. Unique Structural Modifications Are Present in the Lipopolysaccharide from Colistin-Resistant Strains of Acinetobacter baumannii

    Science.gov (United States)

    2013-10-01

    SECURITY CLASSIFICATION OF: Acinetobacter baumannii is a nosocomial opportunistic pathogen that can cause severe infections, including hospital-acquired...distribution is unlimited. Unique Structural Modifications Are Present in the Lipopolysaccharide from Colistin-Resistant Strains of Acinetobacter baumannii ...from Colistin-Resistant Strains of Acinetobacter baumannii Report Title Acinetobacter baumannii is a nosocomial opportunistic pathogen that can cause

  18. Age-related changes in body composition in laboratory rats: Strain and gender comparisons

    Science.gov (United States)

    Long Evans (LE), Sprague Dawley (SD), Fischer 344 (F344), and Brown Norway (BN) rats are all commonly used as laboratory research subjects. These strains have been studied under many conditions, but few studies have measured changes in body composition as the animals age. Underst...

  19. PCR for the Specific Detection of an Escherichia coli O157:H7 Laboratory Control Strain.

    Science.gov (United States)

    Knowles, Michael; Lambert, Dominic; Huszczynski, George; Gauthier, Martine; Blais, Burton W

    2015-09-01

    Control strains of bacterial pathogens such as Escherichia coli O157:H7 are commonly processed in parallel with test samples in food microbiology laboratories as a quality control measure to assure the satisfactory performance of materials used in the analytical procedure. Before positive findings can be reported for risk management purposes, analysts must have a means of verifying that pathogenic bacteria (e.g., E. coli O157:H7) recovered from test samples are not due to inadvertent contamination with the control strain routinely handled in the laboratory environment. Here, we report on the application of an in-house bioinformatic pipeline for the identification of unique genomic signature sequences in the development of specific oligonucleotide primers enabling the identification of a common positive control strain, E. coli O157:H7 (ATCC 35150), using a simple PCR procedure.

  20. Assessment of strains of Pseudomonas syringae pv. tomato from Tanzania for resistance to copper and streptomycin

    DEFF Research Database (Denmark)

    Shenge, K.C.; Wydra, K.; Mabagala, M.B.

    2008-01-01

    Fifty-six strains of Pseudomonas syringae pv. tomato (P.s. pv. tomato) were collected from tomato-producing areas in Tanzania and assessed for resistance to copper and antibiotics. The collection was done from three tomato-producing regions (Morogoro, Arusha and Iringa), representing three...... different ecological conditions in the country. After isolation and identification, the P. s. pv. tomato strains were grown on King's medium B (KB) amended with 20% copper sulphate (w/v). The strains were also assessed for resistance to antibiotics. Results indicated that there was widespread resistance...... of the P. s. pv. tomato strains to copper sulphate. The highest level of resistance was recorded from the Arusha region (Northern Tanzania), 83.3% of the P. s. pv. tomato strains from that region showed resistance to copper sulphate. This was followed by Iringa region (Southern Tanzania), from where...

  1. Survival of a Rifampicin-Resistant Pseudomonas fluorescens Strain in Nine Mollisols

    Directory of Open Access Journals (Sweden)

    Tami L. Stubbs

    2014-01-01

    Full Text Available Pseudomonas fluorescens strain D7 (P.f. D7 is a naturally occurring soil bacterium that shows promise as a biological herbicide to inhibit growth of annual grass weeds, including downy brome (Bromus tectorum L., in crop- and rangelands. Pseudomonas fluorescens strain D7rif (P.f. D7rif is a rifampicin-resistant strain of P.f. D7. One of the greatest obstacles to successful biological weed control is survival of the organism under field conditions. Nine soils in the taxonomic order of Mollisols, collected from downy brome-infested areas of the Western and Central United States, were inoculated with P.f. D7rif and incubated in the laboratory to determine the effects of soil type, soil properties, incubation temperature, and soil water potential on survival of P.f. D7rif over 63 days. Silt loam soils from Lind, Washington, and Moro, Oregon, sustained the highest P.f. D7rif populations, and recovery was the lowest from Pendleton, Oregon soil. Survival and recovery of P.f. D7rif varied with soil type and temperature but not with the two soil water potentials tested. After 63 days, P.f. D7rif was recovered at levels greater than log 5.5 colony forming units (CFU g−1 soil from five of the nine test soils, a level adequate to suppress downy brome under field or range conditions.

  2. LINA: a laboratory inventory system for oligonucleotides, microbial strains, and cell lines.

    Science.gov (United States)

    Yousef, A F; Baggili, I M; Bartlett, G; Kane, M D; Mymryk, J S

    2011-02-01

    In this article, we present the Laboratory Inventory Network Application (LINA), a software system that assists research laboratories in keeping track of their collections of biologically relevant materials. This open source application uses relational Microsoft Access database technology as a back end and a Microsoft .NET application as a front end. Preconstructed table templates are provided that contain standardized and customizable data fields. As new samples are added to the inventory, each is provided with a unique laboratory identifier, which is assigned automatically and sequentially, allowing rapid retrieval when a given reagent is required. The LINA contains a number of useful search tools including a general search, which allows database searches using up to four user-defined criteria. The LINA represents an easily implemented and useful organizational tool for biological laboratories with large numbers of strains, clones, or other reagents. Copyright © 2011 Society for Laboratory Automation and Screening. All rights reserved.

  3. Comparative Genomics of Environmental and Clinical Stenotrophomonas maltophilia Strains with Different Antibiotic Resistance Profiles.

    Science.gov (United States)

    Youenou, Benjamin; Favre-Bonté, Sabine; Bodilis, Josselin; Brothier, Elisabeth; Dubost, Audrey; Muller, Daniel; Nazaret, Sylvie

    2015-08-14

    Stenotrophomonas maltophilia, a ubiquitous Gram-negative γ-proteobacterium, has emerged as an important opportunistic pathogen responsible for nosocomial infections. A major characteristic of clinical isolates is their high intrinsic or acquired antibiotic resistance level. The aim of this study was to decipher the genetic determinism of antibiotic resistance among strains from different origins (i.e., natural environment and clinical origin) showing various antibiotic resistance profiles. To this purpose, we selected three strains isolated from soil collected in France or Burkina Faso that showed contrasting antibiotic resistance profiles. After whole-genome sequencing, the phylogenetic relationships of these 3 strains and 11 strains with available genome sequences were determined. Results showed that a strain's phylogeny did not match their origin or antibiotic resistance profiles. Numerous antibiotic resistance coding genes and efflux pump operons were revealed by the genome analysis, with 57% of the identified genes not previously described. No major variation in the antibiotic resistance gene content was observed between strains irrespective of their origin and antibiotic resistance profiles. Although environmental strains generally carry as many multidrug resistant (MDR) efflux pumps as clinical strains, the absence of resistance-nodulation-division (RND) pumps (i.e., SmeABC) previously described to be specific to S. maltophilia was revealed in two environmental strains (BurA1 and PierC1). Furthermore the genome analysis of the environmental MDR strain BurA1 showed the absence of SmeABC but the presence of another putative MDR RND efflux pump, named EbyCAB on a genomic island probably acquired through horizontal gene transfer. © The Author(s) 2015. Published by Oxford University Press on behalf of the Society for Molecular Biology and Evolution.

  4. Susceptibility Status and Resistance Mechanisms in Permethrin-Selected, Laboratory Susceptible and Field-Collected Aedes aegypti from Malaysia

    Directory of Open Access Journals (Sweden)

    Rosilawati Rasli

    2018-04-01

    Full Text Available This study is intended to provide a comprehensive characterization of the resistance mechanisms in the permethrin-selected (IMR-PSS and laboratory susceptible (IMR-LS Aedes aegypti strain from Malaysia. Both IMR-PSS and IMR-LS provide a standard model for use in assessing the pyrethroid resistance in field-collected strains collected from three dengue hotspots: the Taman Seri Bayu (TSB, the Flat Camar (FC, and the Taman Dahlia (TD. Two established methods for determining the resistance mechanisms of the pyrethroid are the quantification of detoxification enzymes via enzyme microassay and the nucleotide sequencing of the domain 2 region from segment 1 to 6 via classical polymerase chain reaction (PCR amplification—were employed. Enzyme activities in IMR-LS served as the resistance threshold reference, providing a significant standard for comparison with IMR-PSS and other field-collected strains. The amino acids in the domain 2 region of voltage-gated sodium channel (Vgsc of IMR-LS were served as the reference for detection of any changes of the knockdown resistance (kdr alleles in IMR-PSS and field-collected strains. Studies clearly indicated that the IMR-LS was highly susceptible to insecticides, whilst the IMR-PSS was highly resistant to pyrethroids and conferred with two resistance mechanisms: the elevated oxidase enzyme activity and the altered target-site mutations. Mutations of V1023G alone, and the combination mutations of V1023G with S996P in IMR-PSS, as well as the in field-collected Aedes aegypti strain, indicate the spread of the (kdr gene in Aedes aegypti, particularly in dengue-endemic areas in Malaysia.

  5. Genetic diversity and antimicrobial resistance  in Streptococcus agalactiae strains recovered from female carriers in the Bucharest area

    Directory of Open Access Journals (Sweden)

    Codru?a-Romani?a Usein

    2014-04-01

    Full Text Available For the first time, we used multilocus sequence typing (MLST to understand how Romanian group B streptococcus (GBS strains fit into the global GBS population structure. Colonising isolates recovered from adult human females were tested for antibiotic resistance, were molecularly serotyped based on the capsular polysaccharide synthesis (cps gene cluster and further characterised using a set of molecular markers (surface protein genes, pilus-encoded islands and mobile genetic elements inserted in the scpB-lmb intergenic region. Pulsed-field gel electrophoresis was used to complement the MLST clonal distribution pattern of selected strains. Among the 55 strains assigned to six cps types (Ia, Ib, II-V, 18 sequence types (STs were identified by MLST. Five STs represented new entries to the MLST database. The prevalent STs were ST-1, ST-17, ST-19 and ST-28. Twenty molecular marker profiles were identified. The most common profiles (rib+GBSi1+PI-1, rib+GBSi1+PI-1, PI-2b and alp2/3+PI-1, PI-2a were associated with the cps III/ST-17 and cps V/ST-1 strains. A cluster of fluoroquinolone-resistant strains was detected among the cps V/ST-19 members; these strains shared alp1 and IS1548 and carried PI-1, PI-2a or both. Our results support the usefulness of implementing an integrated genotyping system at the reference laboratory level to obtain the reliable data required to make comparisons between countries.

  6. Antimicrobial resistance and characterization of Helicobacter pylori strains isolated from Mexican adults with clinical outcome.

    Science.gov (United States)

    Chihu, L; Ayala, G; Mohar, A; Hernández, A; Herrera-Goepfert, R; Fierros, G; González-Márquez, H; Silva, J

    2005-06-01

    Eradication of Helicobacter pylori infection in Mexico is of great importance due to the elevated seroprevalence, however, there is yet very little information about antibiotic resistance rates in H. pylori isolates in our country. We analyzed susceptibility to three antimicrobials used in therapy of 49 H. pylori strains isolated from patients with active chronic gastritis, active chronic gastritis with lymphoid follicles, intestinal metaplasia and gastric cancer. All isolated strains were susceptible to amoxicillin, 28 (58%) were resistant to metronidazole and 2 (4%) were resistant to both clarithromycin and metronidazole. Sequence analysis of the 23S rRNA of the two clarithromycin-resistant strains showed the A2142G mutation in one and A2143G and T2182C mutations in the other. Metronidazole resistance was associated with cagA negative strains with a frequency of 82% (9/11). No significant correlation was found between vacA s/m alleles and metronidazole resistance.

  7. The Influence of Insecticide Resistance, Age, Sex, and Blood Feeding Frequency on Thermal Tolerance of Wild and Laboratory Phenotypes of Anopheles funestus (Diptera: Culicidae).

    Science.gov (United States)

    Lyons, C L; Oliver, S V; Hunt, R H; Coetzee, M

    2016-03-01

    Resistance to insecticides is a global phenomenon and is increasing at an unprecedented rate. How resistant and susceptible strains of malaria vectors might differ in terms of life history and basic biology is often overlooked, despite the potential importance of such information in light of changing climates. Here, we investigated the upper thermal limits (ULT50) of wild and laboratory strains of Anopheles funestus Giles mosquitoes, including resistance status, sex, age, and blood feeding status as potential factors influencing ULT50. No significant differences in ULT50 were observed between strains displaying different resistance patterns, nor was there a significant difference between wild and laboratory strains. In some instances, strains showed a senescence response, displaying decreased ULT50 with an increase in age, and differences between males and females (females displaying higher ULT50 than males). Blood feeding did not seem to influence ULT50 in any way. For An. funestus, it seems evident that there is no cost to resistance despite what is displayed in other anopheline species. This could have significant impacts for vector control, with resistant populations of An. funestus performing just as well, if not better, than susceptible strains, especially under changing environmental conditions such as those expected to occur with climate change.

  8. Growth temperature exerts differential physiological and transcriptional responses in laboratory and wine strains of Saccharomyces cerevisiae

    DEFF Research Database (Denmark)

    Pizarra, Francisco J.; Jewett, Michael Christopher; Nielsen, Jens

    2008-01-01

    exhibited higher fermentation rates. To elucidate mechanistic differences controlling the growth temperature response and underlying adaptive mechanisms between the strains, DNA microarrays and targeted metabolome analysis were used. We identified 1,007 temperature-dependent genes and 473 strain......-dependent genes. The transcriptional response was used to identify highly correlated gene expression subnetworks within yeast metabolism. We showed that temperature differences most strongly affect nitrogen metabolism and the heat shock response. A lack of stress response element-mediated gene induction, coupled...... environmental conditions and the organoleptic properties that they confer to wine. Here, we used a two-factor design to study the responses of a standard laboratory strain, CEN.PK113-7D, and an industrial wine yeast strain, EC1118, to growth temperatures of 15 degrees C and 30 degrees C in nitrogen...

  9. Salmonella serovars and antimicrobial resistance in strains isolated from wild animals in captivity in Sinaloa, Mexico

    OpenAIRE

    Silva-Hidalgo, Gabriela; López-Valenzuela, Martin; Juárez-Barranco, Felipe; Montiel-Vázquez, Edith; Valenzuela-Sánchez, Beatriz

    2014-01-01

    The aim of the present study was to evaluate the frequency of antibiotic resistance in Salmonella spp. strains from wild animals in captivity at the Culiacan Zoo and the Mazatlan Aquarium in Sinaloa, Mexico. We identified 17 different Salmonella enterica serovars at a prevalence of 19.90% (Culiacan Zoo) and 6.25% (Mazatlan Aquarium). Antibiotic sensitivity tests revealed that, of the 83 strains studied, 100% were multidrug resistant (MDR). The drugs against which the greatest resistance was o...

  10. [Multidrug-Resistant Tuberculosis by Strains of Beijing Family, in Patients from Lisbon, Portugal: Preliminary Report].

    Science.gov (United States)

    Maltez, Fernando; Martins, Teresa; Póvoas, Diana; Cabo, João; Peres, Helena; Antunes, Francisco; Perdigão, João; Portugal, Isabel

    2017-03-31

    Beijing family strains of Mycobacterium tuberculosis are associated with multidrug-resistance. Although strains of the Lisboa family are the most common among multidrug-resistant and extensively drug-resistant patients in the region, several studies have reported the presence of the Beijing family. However, the features of patients from whom they were isolated, are not yet known. Retrospective study involving 104 multidrug-resistant and extensively drug-resistant strains of Mycobacterium tuberculosis, from the same number of patients, isolated and genotyped between 1993 and 2015 in Lisbon. We assessed the prevalence of strains of both families and the epidemiologic and clinical features of those infected with Beijing family strains. Seventy-four strains (71.2%) belonged to the Lisboa family, 25 (24.0%) showed a unique genotypic pattern and five (4.8%) belonged to the Beijing family, the latter identified after 2009. Those infected with Beijing family strains were angolan (n = 1), ukrainian (n = 2) and portuguese (n = 2), mainly young-aged and, four of five immunocompetent and with no past history of tuberculosis. All had multidrug-resistant tuberculosis. We did not find any distinctive clinical or radiological features, neither a predominant resistance pattern. Cure rate was high (four patients). Although the number of infected patients with Beijing strains was small, it suggests an important proportion of primary tuberculosis, a potential for transmission in the community but also a better clinical outcome when compared to other reported strains, such as W-Beijing and Lisboa. Although Lisboa family strains account for most of the multidrug and extensively drug-resistant tuberculosis cases in Lisbon area, Beijing strains are transmitted in the city and might change the local characteristics of the epidemics.

  11. Combinatorial Strategies for Improving Multiple-Stress Resistance in Industrially Relevant Escherichia coli Strains

    DEFF Research Database (Denmark)

    Lennen, Rebecca; Herrgard, Markus

    2014-01-01

    conditions and two combinations of individual stresses. A subset of the identified loss-of-function mutants were selected for a combinatorial approach, where strains with combinations of two and three gene deletions were systematically constructed and tested for single and multistress resistance....... These approaches allowed identification of (i) strain-background-specific stress resistance phenotypes, (ii) novel gene deletion mutants in E. coli that confer single and multistress resistance in a strain-background-dependent manner, and (iii) synergistic effects of multiple gene deletions that confer improved...... resistance over single deletions. The results of this study underscore the suboptimality and strain-specific variability of the genetic network regulating growth under stressful conditions and suggest that further exploration of the combinatorial gene deletion space in multiple strain backgrounds is needed...

  12. Plasmid Mediated Antibiotic and Heavy Metal Resistance in Bacillus Strains Isolated From Soils in Rize, Turkey

    Directory of Open Access Journals (Sweden)

    Elif SEVİM

    2015-09-01

    Full Text Available Fifteen Bacillus strains which were isolated from soil samples were examined for resistance to 17 different antibiotics (ampicillin, methicillin, erythromycin, norfloxacin, cephalotine, gentamycin, ciprofloxacin, streptomycin, tobramycin, chloramphenicol, trimethoprim-sulfamethoxazole, tetracycline, vancomycin, oxacilin, neomycin, kanamycin and, novabiocin and to 10 different heavy metals (copper, lead, cobalt, chrome, iron, mercury, zinc, nickel, manganese and, cadmium and for the presence of plasmid DNA. A total of eleven strains (67% were resistant to at least one antibiotic. The most common resistance was observed against methicillin and oxacillin. The most resistance strains were found as Bacillus sp. B3 and Bacillus sp. B11. High heavy metal resistance against copper, chromium, zinc, iron and nickel was detected, but mercury and cobalt resistance was not detected, except for 3 strains (B3, B11, and B12 which showed mercury resistance. It has been determined that seven Bacillus strains have plasmids. The isolated plasmids were transformed into the Bacillus subtilis W168 and it was shown that heavy metal and antibiotic resistance determinants were carried on these plasmids. These results showed that there was a correlation between plasmid content and resistance for both antibiotic and heavy metal resistance

  13. Travel Destinations and Sexual Behavior as Indicators of Antibiotic Resistant Shigella Strains--Victoria, Australia.

    Science.gov (United States)

    Lane, Courtney R; Sutton, Brett; Valcanis, Mary; Kirk, Martyn; Walker, Cathryn; Lalor, Karin; Stephens, Nicola

    2016-03-15

    Knowledge of relationships between antibiotic susceptibility of Shigella isolates and travel destination or other risk factors can assist clinicians in determining appropriate antibiotic therapy prior to susceptibility testing. We describe relationships between resistance patterns and risk factors for acquisition in Shigella isolates using routinely collected data for notified cases of shigellosis between 2008 and 2012 in Victoria, Australia. We included all shigellosis patients notified during the study period, where Shigella isolates were tested for antimicrobial sensitivity using Clinical and Laboratory Standards Institute breakpoints. Cases were interviewed to collect data on risk factors, including recent travel. Data were analyzed using Stata 13.1 to examine associations between risk factors and resistant strains. Of the 500 cases of shigellosis, 249 were associated with overseas travel and 210 were locally acquired. Forty-six of 51 isolates of Indian origin displayed decreased susceptibility or resistance to ciprofloxacin. All isolates of Indonesian origin were susceptible to ciprofloxacin. Twenty-six travel-related isolates were resistant to all tested oral antimicrobials. Male-to-male sexual contact was the primary risk factor for 80% (120/150) of locally acquired infections among adult males, characterized by distinct periodic Shigella sonnei outbreaks. Clinicians should consider travel destination as a marker for resistance to common antimicrobials in returning travelers, where severe disease requires empirical treatment prior to receipt of individual sensitivity testing results. Repeated outbreaks of locally acquired shigellosis among men who have sex with men highlight the importance of prevention and control measures in this high-risk group. © The Author 2015. Published by Oxford University Press for the Infectious Diseases Society of America. All rights reserved. For permissions, e-mail journals.permissions@oup.com.

  14. Identification and Characterization of a Serious Multidrug Resistant Stenotrophomonas maltophilia Strain in China

    Directory of Open Access Journals (Sweden)

    Yan Zhao

    2015-01-01

    Full Text Available An S. maltophilia strain named WJ66 was isolated from a patient; WJ66 showed resistance to more antibiotics than the other S. maltophilia strains. This bacteraemia is resistant to sulphonamides, or fluoroquinolones, while the representative strain of S. maltophilia, K279a, is sensitive to both. To explore drug resistance determinants of this strain, the draft genome sequence of WJ66 was determined and compared to other S. maltophilia sequences. Genome sequencing and genome-wide evolutionary analysis revealed that WJ66 was highly homologous with the strain K279a, but strain WJ66 contained additional antibiotic resistance genes. Further analysis confirmed that strain WJ66 contained an amino acid substitution (Q83L in fluoroquinolone target GyrA and carried a class 1 integron, with an aadA2 gene in the resistance gene cassette. Homology analysis from the pathogen-host interaction database showed that strain WJ66 lacks raxST and raxA, which is consistent with K279a. Comparative genomic analyses revealed that subtle nucleotide differences contribute to various significant phenotypes in close genetic relationship strains.

  15. Antibiotic resistance of Enterobacteriaceae strains isolated from different animals gastrointestinal tracts

    Directory of Open Access Journals (Sweden)

    Lukáš Hleba

    2015-05-01

    Full Text Available In this study we monitored antibiotic resistance in Enterobacteriaceae strains isolated from different animals gastrointestinal tracts  (GIT. We isolated Enterobacteriaceae from chicken, ducks, lambs, pigs, sheeps, cows and rabbits collected from slovakian farms. Enterobacteriaceae strains were cultivated on MacConkey agar at 35° ± 2°C at 24 hours. Pure cultures of Enterobacteriaceae strains were obtained by four-way streak method on Chromogenic coliform agar. Identification of purified Enterobacteriaceae strains were done by Enterotest 24 and MALDI TOF MS. For susceptibility testing disk diffusion method was used according by EUCAST. We determined the most resistance in Enterobacteriaceae strains against streptomycin, tetracycline, ampicillin, piperecillin, levofloxacine, chloramphenicol and smaller level of resistance against amikacin, ceftriaxone and ofloxacine. Equally we detected resistance to more antibiotics in one strain. The most resistance was Salmonella enterica ser. Typhimurium. Also E. coli was resistance against four antibiotics and Raoultella ornithinolytica too. Antibiotic resistance was found in other isolated strains too.

  16. Virulence factors, serogroups and antimicrobial resistance properties of Escherichia coli strains in fermented dairy products.

    Science.gov (United States)

    Dehkordi, Farhad Safarpoor; Yazdani, Farshad; Mozafari, Jalal; Valizadeh, Yousef

    2014-04-07

    From a clinical perspective, it is essential to know the microbial safety of fermented dairy products. Doogh and kashk are fermented dairies. These products are used by millions of people but their microbial qualities are unknown. Shiga toxin producing Escherichia coli (STEC) is one of the most commonly detected pathogens in the cases of food poisoning and food-borne illnesses. The present investigation was carried out in order to study the molecular characterization and antimicrobial resistance properties of STEC strains isolated from fermented dairy products. Six hundred fermented dairy samples were collected and immediately transferred to the laboratory. All samples were cultured immediately and those that were E. coli-positive were analyzed for the presence of O157 , O26, O103, O111, O145, O45, O91, O113, O121 and O128 STEC serogroups, tetA, tetB, blaSHV, CITM, cmlA, cat1, aadA1, dfrA1, qnr, aac (3)-IV, sul1 and ereA antibiotic resistance genes and stx1, stx2, eaeA, ehly, cnf1, cnf2, iutA, cdtB, papA, traT, sfaS and fyuA virulence factors using PCR. Antimicrobial susceptibility testing was performed also using disk diffusion methodology with Mueller-Hinton agar. Fifty out of 600 (8.33%) dairy samples harbored E. coli. In addition, yoghurt was the most commonly contaminated dairy. O157 (26%) and O26 (12%) were the most commonly detected serogroups. A significant difference was found between the frequency of Attaching and Effacing E. coli and Enterohaemorrhagic E. coli (P resistance against tetracycline (tetA and tetB) (76% and 70%, respectively), cephalothin (blaSHV) (38%), ampicillin (CITM) (36%) and gentamicin (aac (3)-IV) (32%) were the most commonly detected. High resistance levels to tetracycline (84%), penicillin (46%), ampicillin (38%) and streptomycin (36%) were observed. Fermented dairy products can easily become contaminated by antibiotic resistant STEC strains. Our findings should raise awareness about antibiotic resistance in Iran. Clinicians should

  17. Assessing permethrin resistance in the stable fly (Diptera: Muscidae) in Florida by using laboratory selections and field evaluations.

    Science.gov (United States)

    Pitzer, Jimmy B; Kaufman, Phillip E; Tenbroeck, Saundra H

    2010-12-01

    Insecticide resistance in the stable fly, Stomoxys calcitrans (L.) (Diptera: Muscidae),has been demonstrated previously, but mostly with insecticides that are no longer used, such as the organochlorines. Resistance to commonly used pyrethroids has been evaluated twice, but only in the midwestern United States. Stable fly susceptibility to a commonly used pyrethroid, permethrin, was determined in Florida to assess the possibility of resistance development. Diagnostic concentration evaluations of three stable fly field strains demonstrated a maximum of 57 and 21% survival to permethrin residues of 3x and 10x the LC99 of a susceptible strain, respectively. Stable flies from an equine facility with no reported insecticide use demonstrated approximately 20% survival with a 3x diagnostic concentration. Despite a distance of 91-km between field collection sites, survival profiles of field-collected stable fly strains were similar. Although an established stable fly colony collected from a local dairy previously expressed low level resistance to permethrin residues, five generations of laboratory permethrin selection increased resistance 15-fold.

  18. Structure-Activity Relationships of Diverse Oxazolidinones for Linezolid-Resistant Staphylococcus aureus Strains Possessing the cfr Methyltransferase Gene or Ribosomal Mutations▿

    Science.gov (United States)

    Locke, Jeffrey B.; Finn, John; Hilgers, Mark; Morales, Gracia; Rahawi, Shahad; G. C., Kedar; Picazo, Juan José; Im, Weonbin; Shaw, Karen Joy; Stein, Jeffrey L.

    2010-01-01

    Staphylococcal resistance to linezolid (LZD) is mediated through ribosomal mutations (23S rRNA or ribosomal proteins L3 and L4) or through methylation of 23S rRNA by the horizontally transferred Cfr methyltransferase. To investigate the structural basis for oxazolidinone activity against LZD-resistant (LZDr) strains, we compared structurally diverse, clinically relevant oxazolidinones, including LZD, radezolid (RX-1741), TR-700 (torezolid), and a set of TR-700 analogs (including novel CD-rings and various A-ring C-5 substituents), against a panel of laboratory-derived and clinical LZDr Staphylococcus aureus strains possessing a variety of resistance mechanisms. Potency against all strains was correlated with optimization of C- and D-rings, which interact with more highly conserved regions of the peptidyl transferase center binding site. Activity against cfr strains was retained with either hydroxymethyl or 1,2,3-triazole C-5 groups but was reduced by 2- to 8-fold in compounds with acetamide substituents. LZD, which possesses a C-5 acetamide group and lacks a D-ring substituent, demonstrated the lowest potency against all strains tested, particularly against cfr strains. These data reveal key features contributing to oxazolidinone activity and highlight structural tradeoffs between potency against susceptible strains and potency against strains with various resistance mechanisms. PMID:20837751

  19. Effect of Bacteriophages on the Growth of Flavobacterium psychrophilum and Development of Phage-Resistant Strains.

    Science.gov (United States)

    Christiansen, Rói Hammershaimb; Madsen, Lone; Dalsgaard, Inger; Castillo, Daniel; Kalatzis, Panos G; Middelboe, Mathias

    2016-05-01

    The controlling effect of single and multiple phages on the density of Flavobacterium psychrophilum at different initial multiplicity of infection (MOI) was assessed in batch cultures to explore the potential for phage-based treatment of this important fish pathogen. A high initial phage concentration (MOI = 0.3-4) was crucial for efficient viral lysis, resulting in a 10(4)-10(5)-fold reduction of phage-sensitive cells (both single phages and phage cocktails), which was maintained throughout the incubation (>10 days). Following cell lysis, regrowth of phage-resistant strains was examined and resistant strains were isolated for further characterization. The application of a mathematical model allowed simulation of phage-host interactions and resistance development, confirming indications from strain isolations that phage-sensitive strains dominated the regrowing population (>99.8%) at low MOI and phage-resistant strains (>87.8%) dominated at high MOI. A cross-infectivity test covering 68 isolated strains and 22 phages resulted in 23 different host susceptibility patterns, with 20 of the isolates being resistant to all the applied phages. Eleven isolated strains with different susceptibility patterns had lower growth rates (0.093 to 0.31 h(-1)) than the host strain (0.33 h(-1)), while 10 of 14 examined strains had lost the ability to take up specific substrates as shown by BIOLOG profiles. Despite increased selection for phage resistance at high MOI, the results emphasize that high initial MOI is essential for fast and effective control of F. psychrophilum infection and suggest that the small populations of resistant clones had reduced competitive abilities relative to the sensitive ancestral strain.

  20. Bacteriophages drive strain diversification in a marine Flavobacterium: implications for phage resistance and physiological properties.

    Science.gov (United States)

    Middelboe, Mathias; Holmfeldt, Karin; Riemann, Lasse; Nybroe, Ole; Haaber, Jakob

    2009-08-01

    Genetic, structural and physiological differences between strains of the marine bacterium Cellulophaga baltica MM#3 (Flavobacteriaceae) developing in response to the activity of two virulent bacteriophages, Phi S(M) and Phi S(T), was investigated during 3 weeks incubation in chemostat cultures. A distinct strain succession towards increased phage resistance and a diversification of the metabolic properties was observed. During the incubation the bacterial population diversified from a single strain, which was sensitive to 24 tested Cellulophaga phages, into a multistrain and multiresistant population, where the dominant strains had lost susceptibility to up to 22 of the tested phages. By the end of the experiment the cultures reached a quasi steady state dominated by Phi S(T)-resistant and Phi S(M) + Phi S(T)-resistant strains coexisting with small populations of phage-sensitive strains sustaining both phages at densities of > 10(6) plaque forming units (pfu) ml(-1). Loss of susceptibility to phage infection was associated with a reduction in the strains' ability to metabolize various carbon sources as demonstrated by BIOLOG assays. This suggested a cost of resistance in terms of reduced physiological capacity. However, there was no direct correlation between the degree of resistance and the loss of metabolic properties, suggesting either the occurrence of compensatory mutations in successful strains or that the cost of resistance in some strains was associated with properties not resolved by the BIOLOG assay. The study represents the first direct demonstration of phage-driven generation of functional diversity within a marine bacterial host population with significant implications for both phage susceptibility and physiological properties. We propose, therefore, that phage-mediated selection for resistant strains contributes significantly to the extensive microdiversity observed within specific bacterial species in marine environments.

  1. Influence of the local strains on the rounding of the resistivity near Tcin copper oxide superconductors

    International Nuclear Information System (INIS)

    Maza, J.; Torron, C.; Vidal, F.

    1989-01-01

    The effects on the electrical resistivity of a spatially varying local critical temperature T c in HTSC, due for instance to local strains of oxygen variations, is studied. Assuming a Gaussian-like spatial distribution of T c values; the corresponding rounding of the resistivity near and above the resistive temperature T cr does not agree with resistivity data of Y-based or La = based compounds

  2. Origins of albino and hooded rats: implications from molecular genetic analysis across modern laboratory rat strains.

    Science.gov (United States)

    Kuramoto, Takashi; Nakanishi, Satoshi; Ochiai, Masako; Nakagama, Hitoshi; Voigt, Birger; Serikawa, Tadao

    2012-01-01

    Albino and hooded (or piebald) rats are one of the most frequently used laboratory animals for the past 150 years. Despite this fact, the origin of the albino mutation as well as the genetic basis of the hooded phenotype remained unclear. Recently, the albino mutation has been identified as the Arg299His missense mutation in the Tyrosinase gene and the hooded (H) locus has been mapped to the ∼460-kb region in which only the Kit gene exists. Here, we surveyed 172 laboratory rat strains for the albino mutation and the hooded (h) mutation that we identified by positional cloning approach to investigate possible genetic roots and relationships of albino and hooded rats. All of 117 existing laboratory albino rats shared the same albino missense mutation, indicating they had only one single ancestor. Genetic fine mapping followed by de novo sequencing of BAC inserts covering the H locus revealed that an endogenous retrovirus (ERV) element was inserted into the first intron of the Kit gene where the hooded allele maps. A solitary long terminal repeat (LTR) was found at the same position to the ERV insertion in another allele of the H locus, which causes the so called Irish (h(i)) phenotype. The ERV and the solitary LTR insertions were completely associated with the hooded and Irish coat patterns, respectively, across all colored rat strains examined. Interestingly, all 117 albino rat strains shared the ERV insertion without any exception, which strongly suggests that the albino mutation had originally occurred in hooded rats.

  3. Methicillin-resistant Staphylococcus aureus: laboratory detection methods in use in the Republic of Ireland and Northern Ireland.

    LENUS (Irish Health Repository)

    Humphreys, H

    2002-01-01

    There is no universally agreed laboratory protocol for the detection of methicillin-resistant Staphylococcus aureus (MRSA) and hence a variety of approaches are used. As part of an all-island survey of MRSA in the Republic of Ireland (the South) and Northern Ireland (the North), a questionnaire was circulated to 14 participating laboratories in the North and 49 in the South, to determine the methods used to isolate MRSA from clinical specimens, identify S. aureus and test for susceptibility to methicillin. Almost two-thirds (64%) of laboratories in the North but only 16% of laboratories in the South use enrichment culture. There is heavy reliance on commercial kits to confirm the identification of S. aureus in the South but all laboratories in the North use the staphylocoagulase test. More than 90% of all laboratories use a disc method for susceptibility testing and 71% of laboratories in the North supplement this with the E-test; however, a range of methicillin disk concentrations are in use. There is a need to review current laboratory methods used to detect MRSA, with follow-up audit on their implementation. Additional resources may be needed in some laboratories to comply with revised guidelines, and reference facilities are required to assess new commercially available techniques and to confirm the identification of unusual or difficult strains.

  4. Carbamate and Pyrethroid Resistance in the Akron Strain of Anopheles gambiae

    Science.gov (United States)

    Mutunga, James M.; Anderson, Troy D.; Craft, Derek T.; Gross, Aaron D.; Swale, Daniel R.; Tong, Fan; Wong, Dawn M.; Carlier, Paul R.; Bloomquist, Jeffrey R.

    2015-01-01

    Insecticide resistance in the malaria vector, Anopheles gambiae is a serious problem, epitomized by the multi-resistant Akron strain, originally isolated in the country of Benin. Here we report resistance in this strain to pyrethroids and DDT (13-fold to 35-fold compared to the susceptible G3 strain), but surprisingly little resistance to etofenprox, a compound sometimes described as a “pseudo-pyrethroid.” There was also strong resistance to topically-applied commercial carbamates (45-fold to 81-fold), except for the oximes aldicarb and methomyl. Biochemical assays showed enhanced cytochrome P450 monooxygenase and carboxylesterase activity, but not that of glutathione-S-transferase. A series of substituted α,α,α,-trifluoroacetophenone oxime methylcarbamates were evaluated for enzyme inhibition potency and toxicity against G3 and Akron mosquitoes. The compound bearing an unsubstituted phenyl ring showed the greatest toxicity to mosquitoes of both strains. Low cross resistance in Akron was retained by all analogs in the series. Kinetic analysis of acetylcholinesterase activity and its inhibition by insecticides in the G3 strain showed inactivation rate constants greater than that of propoxur, and against Akron enzyme inactivation rate constants similar to that of aldicarb. However, inactivation rate constants against recombinant human AChE were essentially identical to that of the G3 strain. Thus, the acetophenone oxime carbamates described here, though potent insecticides that control resistant Akron mosquitoes, require further structural modification to attain acceptable selectivity and human safety. PMID:26047119

  5. Strain-dependent electrical resistance of multi-walled carbon nanotube/polymer composite films

    International Nuclear Information System (INIS)

    Park, Myounggu; Kim, Hyonny; Youngblood, Jeffrey P

    2008-01-01

    The strain-dependent electrical resistance characteristics of multi-walled carbon nanotube (MWCNT)/polymer composite films were investigated. In this research, polyethylene oxide (PEO) is used as the polymer matrix. Two representative volume fractions of MWCNT/PEO composite films were selected: 0.56 vol% (near the percolation threshold) and 1.44 vol% (away from the percolation threshold) of MWCNT. An experimental setup which can measure electrical resistance and strain simultaneously and continuously has been developed. Unique and repeatable relationships in resistance versus strain were obtained for multiple specimens with different volume fractions of MWCNT. The overall pattern of electrical resistance change versus strain for the specimens tested consists of linear and nonlinear regions. A resistance change model to describe the combination of linear and nonlinear modes of electrical resistance change as a function of strain is suggested. The unique characteristics in electrical resistance change for different volume fractions imply that MWCNT/PEO composite films can be used as tunable strain sensors and for application into embedded sensor systems in structures

  6. RNAi validation of resistance genes and their interactions in the highly DDT-resistant 91-R strain of Drosophila melanogaster.

    Science.gov (United States)

    Gellatly, Kyle J; Yoon, Kyong Sup; Doherty, Jeffery J; Sun, Weilin; Pittendrigh, Barry R; Clark, J Marshall

    2015-06-01

    4,4'-dichlorodiphenyltrichloroethane (DDT) has been re-recommended by the World Health Organization for malaria mosquito control. Previous DDT use has resulted in resistance, and with continued use resistance will increase in terms of level and extent. Drosophila melanogaster is a model dipteran that has many available genetic tools, numerous studies done on insecticide resistance mechanisms, and is related to malaria mosquitoes allowing for extrapolation. The 91-R strain of D. melanogaster is highly resistant to DDT (>1500-fold), however, there is no mechanistic scheme that accounts for this level of resistance. Recently, reduced penetration, increased detoxification, and direct excretion have been identified as resistance mechanisms in the 91-R strain. Their interactions, however, remain unclear. Use of UAS-RNAi transgenic lines of D. melanogaster allowed for the targeted knockdown of genes putatively involved in DDT resistance and has validated the role of several cuticular proteins (Cyp4g1 and Lcp1), cytochrome P450 monooxygenases (Cyp6g1 and Cyp12d1), and ATP binding cassette transporters (Mdr50, Mdr65, and Mrp1) involved in DDT resistance. Further, increased sensitivity to DDT in the 91-R strain after intra-abdominal dsRNA injection for Mdr50, Mdr65, and Mrp1 was determined by a DDT contact bioassay, directly implicating these genes in DDT efflux and resistance. Copyright © 2015 Elsevier Inc. All rights reserved.

  7. Characteristics of Vancomycin-Resistant Enterococcus Strains in the West Balkans: A First Report.

    Science.gov (United States)

    Jakovac, Sanja; Bojić, Elma Ferić; Ibrišimović, Monia Avdić; Tutiš, Borka; Ostojić, Maja; Hukić, Mirsada

    2017-01-01

    Vancomycin-resistant enterococci are among the major causes of nosocomial infections and represent a growing problem in many European countries. Among the most common enterococcal isolates, Enterococcus faecium is considered to be the reservoir of VanA and VanB-mediated resistance to glycopeptides. Enterococci with VanA-mediated resistance can transfer resistance genes to other enterococci and gram-positive bacteria. Hence, monitoring and surveillance of vancomycin-resistant enterococci (VREs) are crucial for the prevention of the spread of glycopeptide resistance. No reports have yet been published that document the resistance rates and typization of VREs in the region of Bosnia and Herzegovina as well as Croatia. In this study, 64 clinical enterococcal strains that were isolated in clinical centers, Mostar, Sarajevo, and Zagreb, were studied and findings regarding characteristics of vancomycin-resistant strains found in the West Balkan region are reported for the first time. All of the strains were identified using conventional phenotypic methods, and the resistance to glycopeptides was determined using the disk diffusion method, Vitek 2, and genotypic Enterococcus assay. The results of genotyping showed that 40 strains were identified as VREs (30% Enterococcus faecalis and 70% E. faecium), while the sensitivity of the phenotypic methods was 87.5%. Furthermore, VanA and VanB resistance types were found in Bosnia and Herzegovina and Croatia, with slightly higher prevalence of the latter (72.5%) over the former (27.5%).

  8. Sensitivity of antibiotic resistant and antibiotic susceptible Escherichia coli, Enterococcus and Staphylococcus strains against ozone.

    Science.gov (United States)

    Heß, Stefanie; Gallert, Claudia

    2015-12-01

    Tolerance of antibiotic susceptible and antibiotic resistant Escherichia coli, Enterococcus and Staphylococcus strains from clinical and wastewater samples against ozone was tested to investigate if ozone, a strong oxidant applied for advanced wastewater treatment, will affect the release of antibiotic resistant bacteria into the aquatic environment. For this purpose, the resistance pattern against antibiotics of the mentioned isolates and their survival after exposure to 4 mg/L ozone was determined. Antibiotic resistance (AR) of the isolates was not correlating with higher tolerance against ozone. Except for ampicillin resistant E. coli strains, which showed a trend towards increased resistance, E. coli strains that were also resistant against cotrimoxazol, ciprofloxacin or a combination of the three antibiotics were similarly or less resistant against ozone than antibiotic sensitive strains. Pigment-producing Enterococcus casseliflavus and Staphylococcus aureus seemed to be more resistant against ozone than non-pigmented species of these genera. Furthermore, aggregation or biofilm formation apparently protected bacteria in subsurface layers from inactivation by ozone. The relatively large variance of tolerance against ozone may indicate that resistance to ozone inactivation most probably depends on several factors, where AR, if at all, does not play a major role.

  9. The resistance of pseudomonas aeruginosa strains to fluoroquinolone group of antibiotics

    Directory of Open Access Journals (Sweden)

    Algun U

    2004-01-01

    Full Text Available Fluoroquinolones are antibiotics that are very effective against many gram negative microorganisms, including P. aeruginosa. However, resistance to these antibiotics has been reported in recent years as well. In this study, the sensivity of 136 P. aeruginosa strains, isolated from various clinical materials, to fluoroquinolones has been investigated. The lowest resistance rate was in ciprofloxacin with 12.5%. The resistance rates of the others were as follows: norfloxacin 14.7%, levofloxacin 16.9%, ofloxacin 19.9% and pefloxacin 28.7%. The 88.2% of the resistant strains to all fluoroquinolones were originated from intensive care unit.

  10. Macrolide Resistance in the Syphilis Spirochete, Treponema pallidum ssp. pallidum: Can We Also Expect Macrolide-Resistant Yaws Strains?

    Science.gov (United States)

    Šmajs, David; Paštěková, Lenka; Grillová, Linda

    2015-10-01

    Treponema pallidum ssp. pallidum (TPA) causes over 10 million new cases of syphilis worldwide whereas T. pallidum ssp. pertenue (TPE), the causative agent of yaws, affects about 2.5 million people. Although penicillin remains the drug of choice in the treatment of syphilis, in penicillin-allergic patients, macrolides have been used in this indication since the 1950s. Failures of macrolides in syphilis treatment have been well documented in the literature and since 2000, there has been a dramatic increase in a number of clinical samples with macrolide-resistant TPA. Scarce data regarding the genetics of macrolide-resistant mutations in TPA suggest that although macrolide-resistance mutations have emerged independently several times, the increase in the proportion of TPA strains resistant to macrolides is mainly due to the spread of resistant strains, especially in developed countries. The emergence of macrolide resistance in TPA appears to require a two-step process including either A2058G or A2059G mutation in one copy of the 23S rRNA gene and a subsequent gene conversion unification of both rRNA genes. Given the enormous genetic similarity that was recently revealed between TPA and TPE strains, there is a low but reasonable risk of emergence and spread of macrolide-resistant yaws strains following azithromycin treatment. © The American Society of Tropical Medicine and Hygiene.

  11. Macrolide Resistance in the Syphilis Spirochete, Treponema pallidum ssp. pallidum: Can We Also Expect Macrolide-Resistant Yaws Strains?

    Science.gov (United States)

    Šmajs, David; Paštěková, Lenka; Grillová, Linda

    2015-01-01

    Treponema pallidum ssp. pallidum (TPA) causes over 10 million new cases of syphilis worldwide whereas T. pallidum ssp. pertenue (TPE), the causative agent of yaws, affects about 2.5 million people. Although penicillin remains the drug of choice in the treatment of syphilis, in penicillin-allergic patients, macrolides have been used in this indication since the 1950s. Failures of macrolides in syphilis treatment have been well documented in the literature and since 2000, there has been a dramatic increase in a number of clinical samples with macrolide-resistant TPA. Scarce data regarding the genetics of macrolide-resistant mutations in TPA suggest that although macrolide-resistance mutations have emerged independently several times, the increase in the proportion of TPA strains resistant to macrolides is mainly due to the spread of resistant strains, especially in developed countries. The emergence of macrolide resistance in TPA appears to require a two-step process including either A2058G or A2059G mutation in one copy of the 23S rRNA gene and a subsequent gene conversion unification of both rRNA genes. Given the enormous genetic similarity that was recently revealed between TPA and TPE strains, there is a low but reasonable risk of emergence and spread of macrolide-resistant yaws strains following azithromycin treatment. PMID:26217043

  12. Analysis of local deformation effects in resistive strain sensing of a submicron-thickness AFM cantilever

    Science.gov (United States)

    Adams, Jonathan D.; Schwalb, Christian H.; Winhold, Marcel; Šńukić, Maja; Huth, Michael; Fantner, Georg E.

    2013-05-01

    Incorporating resistive strain-sensing elements into MEMS devices is a long-standing approach for electronic detection of the device deformation. As the need for more sensitivity trends the device dimensions downwards, the size of the strain-sensor may become comparable to the device size, which can have significant impact on the mechanical behaviour of the device. To study this effect, we modelled a submicron-thickness silicon nitride AFM cantilever with strain-sensing element. Using finite element analysis, we calculated the strain in the sensor elements for a deflected cantilever. The sensor element contributes to a local stiffening effect in the device structure which lowers the strain in the sensor. By varying the sensor geometry, we investigated the degree to which this effect impacts the strain. Minimizing the sensor size increases the strain, but the reduction in sensor cross-sectional area increases the resistance and expected sensor noise. The optimal sensor geometry must therefore account for this effect. We used our analysis to optimize geometric variations of nanogranular tunnelling resistor (NTR) strain sensors arranged in a Wheatstone bridge on a silicon nitride AFM cantilever. We varied the dimensions of each sensor element to maintain a constant cross-sectional area but maximize the strain in the sensor element. Through this approach, we expect a 45% increase in strain in the sensor and corresponding 20% increase in the Wheatstone bridge signal. Our results provide an important consideration in the design geometry of resistive strainsensing elements in MEMS devices.

  13. Polydimethylsiloxane (PDMS-Based Flexible Resistive Strain Sensors for Wearable Applications

    Directory of Open Access Journals (Sweden)

    Jing Chen

    2018-02-01

    Full Text Available There is growing attention and rapid development on flexible electronic devices with electronic materials and sensing technology innovations. In particular, strain sensors with high elasticity and stretchability are needed for several potential applications including human entertainment technology, human–machine interface, personal healthcare, and sports performance monitoring, etc. This article presents recent advancements in the development of polydimethylsiloxane (PDMS-based flexible resistive strain sensors for wearable applications. First of all, the article shows that PDMS-based stretchable resistive strain sensors are successfully fabricated by different methods, such as the filtration method, printing technology, micromolding method, coating techniques, and liquid phase mixing. Next, strain sensing performances including stretchability, gauge factor, linearity, and durability are comprehensively demonstrated and compared. Finally, potential applications of PDMS-based flexible resistive strain sensors are also discussed. This review indicates that the era of wearable intelligent electronic systems has arrived.

  14. Genome-Wide Exome Analysis of Cmv5-Disparate Mouse Strains that Differ in Host Resistance to Murine Cytomegalovirus Infection

    Directory of Open Access Journals (Sweden)

    Alyssa Gillespie

    2017-06-01

    Full Text Available Host resistance to murine cytomegalovirus (MCMV varies in different strains of laboratory mice due to differences in expression of determinants that control and clear viral infection. The major histocompatibility complex class I Dk molecule is one such determinant that controls MCMV through the action of natural killer (NK cells. However, the extent of NK cell–mediated Dk-dependent resistance to infection varies in different mouse strains. The molecular genetic basis of this variation remains unclear. Previous work to examine the Dk effect on MCMV resistance in MA/My × C57L offspring discovered multiple quantitative trait loci (QTL that may serve to modify NK cells or their capacity to respond during MCMV infection. One QTL in particular, Cmv5, was found to regulate the frequency of NK cells and secondary lymphoid organ structure in spleen during MCMV infection. Cmv5 alleles, however, have not been identified. We therefore sequenced and analyzed genome-wide exome (GWE variants, including those aligned to the critical genetic interval, in Cmv5-disparate mouse strains. Their GWE variant profiles were compared to assess strain-specific sequence data integrity and to analyze mouse strain relatedness across the genome. GWE content was further compared against data from the Mouse Genomes Project. This approach was developed as a platform for using GWE variants to define genomic regions of divergence and similarity in different mouse strains while also validating the overall quality of GWE sequence data. Moreover, the analysis provides a framework for the selection of novel QTL candidate sequences, including at the Cmv5 critical region.

  15. Antimicrobial sensitivity and frequency of DRUG resistance among bacterial strains isolated from cancer patients

    International Nuclear Information System (INIS)

    Faiz, M.; Bashir, T.

    2004-01-01

    Blood stream infections (bacteremia) is potentially life threatening. Concomitant with a change in the incidence and epidemiology of infecting organisms, there has been an increase in resistance to many antibiotic compounds. The widespread emergence of resistance among bacterial pathogens has an impact on our ability to treat patients effectively. The changing spectrum of microbial pathogens and widespread emergence of microbial resistance to antibiotic drugs has emphasized the need to monitor the prevalence of resistance in these strains. In the present study frequency of isolation of clinically significant bacteria and their susceptibility and resistance pattern against a wide range of antimicrobial drugs from positive blood cultures collected during 2001-2003 was studied. A total of 102 consecutive isolates were found with 63% gram positive and 44% gram negative strains. The dominating pathogens were Staphylococcus aureus (51%), Streptococci (31%), Pseudomonas (40%), Proteus (13%), Klebsiella (13%). The isolated strains were tested against a wide range of antibiotics belonging to cephalosporins, aminoglycosides and quinolone derivative group by disk diffusion method. It has been observed that isolated strains among gram positive and negative strains showed different level of resistance against aminoglycosides and cephalosporin group of antibiotics with gram positives showing highest number and frequency of resistance against aminoglycosides (40-50%) and cephalosporins.(35-45%) whereas cephalosporins were found to be more effective against gram negatives with low frequency of resistant strains. Cabapenem and quinolone derivative drugs were found to be most effective among other groups in both gram positive and negative strains with 23-41% strains found sensitive to these two drugs. The frequency of sensitive strains against aminoglycoside and cephalosporin in gram negative and gram positive strains were found to be decreasing yearwise with a trend towards an

  16. A new laboratory cultivation of Paramecium bursaria using non-pathogenic bacteria strains.

    Science.gov (United States)

    Bator, Tomasz

    2010-01-01

    In most studies dealing with the laboratory cultivation of paramecia (Paramecium bursaria), Klebsiella pneumoniae bacteria are used to inoculate the medium. However, Klebsiella pneumoniae is a typical pathogen, and its use is always associated with a risk of infection. The aim of the present research was to examine non-pathogenic bacteria strains as components of the medium for Paramecium bursaria. The paramecia were incubated on lettuce infusions bacterized with different bacteria strains: Bacillus subtilis DSM 10, Bacillus megaterium DSM 32, Escherichia coli DSM 498, Micrococcus luteus DSM 348. A strain derived from the natural habitat of Paramecium bursaria was used as the control one. Experiments were conducted under constant light and in the dark. Paramecia cells were counted under a stereomicroscope on consecutive days of incubation. The obtained results show that the most intensive growth of Paramecium bursaria occurs in the presence of Escherichia coli DSM 498. The use of this strain as a component of the medium allows one to obtain a high number of ciliates regardless of the light conditions. It can be concluded that the Paramecium bursaria cultivation procedure can be modified by using the non-pathogenic bacteria strain Escherichia coli DSM 498 instead of Klebsiella pneumoniae.

  17. Impact of Colonization Pressure and Strain Type on Methicillin-Resistant Staphylococcus aureus Transmission in Children

    OpenAIRE

    Popoola, Victor O.; Carroll, Karen C.; Ross, Tracy; Reich, Nicholas G.; Perl, Trish M.; Milstone, Aaron M.

    2013-01-01

    We studied the transmissibility of community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) and healthcare-associated methicillin-resistant S. aureus (HA-MRSA) strains and the association of MRSA colonization pressure and MRSA transmission in critically ill children. Importantly, we found that in hospitalized children MRSA colonization pressure above 10% increases the risk of MRSA transmission 3-fold, and CA-MRSA and HA-MRSA strains have similar transmission dynamics.

  18. Impact of colonization pressure and strain type on methicillin-resistant Staphylococcus aureus transmission in children.

    Science.gov (United States)

    Popoola, Victor O; Carroll, Karen C; Ross, Tracy; Reich, Nicholas G; Perl, Trish M; Milstone, Aaron M

    2013-11-01

    We studied the transmissibility of community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) and healthcare-associated methicillin-resistant S. aureus (HA-MRSA) strains and the association of MRSA colonization pressure and MRSA transmission in critically ill children. Importantly, we found that in hospitalized children MRSA colonization pressure above 10% increases the risk of MRSA transmission 3-fold, and CA-MRSA and HA-MRSA strains have similar transmission dynamics.

  19. Simple test of synergy between ampicillin and vancomycin for resistant strains of Enterococcus faecium.

    OpenAIRE

    Green, M; Barbadora, K; Wadowsky, R M

    1994-01-01

    The combination of ampicillin and vancomycin kills some but not all strains of ampicillin- and vancomycin-resistant Enterococcus faecium. We compared a simple test for synergy utilizing a commercially available microdilution susceptibility system with time-kill studies and determined acceptable breakpoints for this test for 20 strains of ampicillin- and vancomycin-resistant E. faecium. The combination of ampicillin and vancomycin was tested for synergy by time-kill, broth macrodilution, and b...

  20. Antibiotic Resistance in Escherichia Coli Strains Isolated from Urine of Inpatients and Outpatients

    Directory of Open Access Journals (Sweden)

    Abolfazl Davoodabadi

    2012-08-01

    Full Text Available The urinary tract infections regarded as a health problem around the world and not only as an agent of nosocomial infections but also infections in the community. Community acquired UTIs cause significant illness in the first 2 years of life [1]. Urinary tract infections in both inpatient and outpatient are common and widespread use of antibiotics is often the cause of emerging one or more antibiotic-resistant microorganisms [2]. Most studies have shown higher antibiotic resistance in bacterial strains isolated from hospitalized patients than outpatients. In this study, antibiogram was performed using disk diffusion susceptibility method according to NCCLS standards of the International Committee [3]. 8 different antibiotics, including ciprofloxacin (CP: 30 μg, ceftriaxone (CRO: 30 μg, cephalotin (CF: 30 μg, cefixime (CFM: 5 μg, cotrimoxazole (SXT, nalidixic acid (NA: 30 μg, nitrofurantoin (FM: 300 μg, gentamicin (GM: 10 μg were used for antibiogram. During 1388 the total number of urine samples sent to hospital microbiology laboratories valiasr (aj of Arak was 5156, of which 446 samples (65.8% were positive for E. coli culture.

  1. Characterization of an In Vitro-Selected Amoxicillin-Resistant Strain of Helicobacter pylori

    Science.gov (United States)

    DeLoney, Cindy R.; Schiller, Neal L.

    2000-01-01

    An amoxicillin-resistant (Amoxr) strain of Helicobacter pylori was selected for by culturing an amoxicillin-sensitive (Amoxs) strain in increasingly higher concentrations of amoxicillin, resulting in a 133-fold increase in MIC, from 0.03 to 0.06 μg/ml to 4 to 8 μg/ml. This resistance was stable upon freezing for at least 6 months and conferred cross-resistance to seven other β-lactam antibiotics. β-Lactamase activity was not detected in this Amoxr strain; however, analysis of the penicillin-binding protein (PBP) profiles generated from isolated bacterial membranes of the Amoxs parental strain and the Amoxr strain revealed a significant decrease in labeling of PBP 1 by biotinylated amoxicillin (bio-Amox) in the Amoxr strain. Comparative binding studies of PBP 1 for several β-lactams demonstrated that PBP 1 in the Amoxr strain had decreased affinity for mezlocillin but not significantly decreased affinity for penicillin G. In addition, PBP profiles prepared from whole bacterial cells showed decreased labeling of PBP 1 and PBP 2 in the Amoxr strain at all bio-Amox concentrations tested, suggesting a diffusional barrier to bio-Amox or a possible antibiotic efflux mechanism. Uptake analysis of 14C-labeled penicillin G showed a significant decrease in uptake of the labeled antibiotic by the Amoxr strain compared to the Amoxs strain, which was not affected by pretreatment with carbonyl cyanide m-chlorophenylhydrazone, eliminating the possibility of an efflux mechanism in the resistant strain. These results demonstrate that alterations in PBP 1 and in the uptake of β-lactam antibiotics in H. pylori can be selected for by prolonged exposure to amoxicillin, resulting in increased resistance to this antibiotic. PMID:11083642

  2. Study on the behavior of resistance strain gages in nuclear radiation environments

    International Nuclear Information System (INIS)

    Kumagai, Katsuaki; Yokoo, Hiroshi; Kitahara, Tanemichi; Kaieda, Keisuke

    1975-08-01

    A series of irradiation experiments were carried out on the behavior of resistance strain gages in nuclear radiation environments. The gages made of bakelite base and advance (nickel-copper alloy) wire were bonded to stainless-steel or aluminium-alloy plates. They were inserted into an in-pile helium loop TLG-1 installed in the JRR-2 reactor, and irradiated at 80 0 C for nearly 300 hours, during which the apparent strain and the leakage current through the base material between the resistance wire and the plate were measured. The results are summarized in the following: (1) The sensitivity change and the insulation-resistance deterioration of the gage are hardly observed. (2) The apparent strain observed can be divided into two components; one dependent on the radiation intensity and the other on the radiation fluence. Both of them indicate the decrease of the gage resistance. (3) The former apparent strain is possibly due to the leakage current through the base material induced by gamma-rays. The latter may be ascribed to the decrease of the wire resistance caused by the radiation damage. (4) Either the half-bridge or full-bridge method makes it possible to compensate the apparent strain and to measure static strain for a few days satisfactorily as well as dynamic strain. (auth.)

  3. Hospital-community interactions foster coexistence between methicillin-resistant strains of Staphylococcus aureus.

    Directory of Open Access Journals (Sweden)

    Roger Kouyos

    2013-02-01

    Full Text Available Methicillin-resistant Staphylococcus aureus (MRSA is an important cause of morbidity and mortality in both hospitals and the community. Traditionally, MRSA was mainly hospital-associated (HA-MRSA, but in the past decade community-associated strains (CA-MRSA have spread widely. CA-MRSA strains seem to have significantly lower biological costs of resistance, and hence it has been speculated that they may replace HA-MRSA strains in the hospital. Such a replacement could potentially have major consequences for public health, as there are differences in the resistance spectra of the two strains as well as possible differences in their clinical effects. Here we assess the impact of competition between HA- and CA-MRSA using epidemiological models which integrate realistic data on drug-usage frequencies, resistance profiles, contact, and age structures. By explicitly accounting for the differing antibiotic usage frequencies in the hospital and the community, we find that coexistence between the strains is a possible outcome, as selection favors CA-MRSA in the community, because of its lower cost of resistance, while it favors HA-MRSA in the hospital, because of its broader resistance spectrum. Incorporating realistic degrees of age- and treatment-structure into the model significantly increases the parameter ranges over which coexistence is possible. Thus, our results indicate that the large heterogeneities existing in human populations make coexistence between hospital- and community-associated strains of MRSA a likely outcome.

  4. Hospital-Community Interactions Foster Coexistence between Methicillin-Resistant Strains of Staphylococcus aureus

    Science.gov (United States)

    Kouyos, Roger; Klein, Eili; Grenfell, Bryan

    2013-01-01

    Methicillin-resistant Staphylococcus aureus (MRSA) is an important cause of morbidity and mortality in both hospitals and the community. Traditionally, MRSA was mainly hospital-associated (HA-MRSA), but in the past decade community-associated strains (CA-MRSA) have spread widely. CA-MRSA strains seem to have significantly lower biological costs of resistance, and hence it has been speculated that they may replace HA-MRSA strains in the hospital. Such a replacement could potentially have major consequences for public health, as there are differences in the resistance spectra of the two strains as well as possible differences in their clinical effects. Here we assess the impact of competition between HA- and CA-MRSA using epidemiological models which integrate realistic data on drug-usage frequencies, resistance profiles, contact, and age structures. By explicitly accounting for the differing antibiotic usage frequencies in the hospital and the community, we find that coexistence between the strains is a possible outcome, as selection favors CA-MRSA in the community, because of its lower cost of resistance, while it favors HA-MRSA in the hospital, because of its broader resistance spectrum. Incorporating realistic degrees of age- and treatment-structure into the model significantly increases the parameter ranges over which coexistence is possible. Thus, our results indicate that the large heterogeneities existing in human populations make coexistence between hospital- and community-associated strains of MRSA a likely outcome. PMID:23468619

  5. Competitive Fitness of Fluconazole-Resistant Clinical Candida albicans Strains.

    Science.gov (United States)

    Popp, Christina; Hampe, Irene A I; Hertlein, Tobias; Ohlsen, Knut; Rogers, P David; Morschhäuser, Joachim

    2017-07-01

    The pathogenic yeast Candida albicans can develop resistance to the widely used antifungal agent fluconazole, which inhibits ergosterol biosynthesis. Resistance is often caused by gain-of-function mutations in the transcription factors Mrr1 and Tac1, which result in constitutive overexpression of multidrug efflux pumps, and Upc2, which result in constitutive overexpression of ergosterol biosynthesis genes. However, the deregulated gene expression that is caused by hyperactive forms of these transcription factors also reduces the fitness of the cells in the absence of the drug. To investigate whether fluconazole-resistant clinical C. albicans isolates have overcome the fitness costs of drug resistance, we assessed the relative fitness of C. albicans isolates containing resistance mutations in these transcription factors in competition with matched drug-susceptible isolates from the same patients. Most of the fluconazole-resistant isolates were outcompeted by the corresponding drug-susceptible isolates when grown in rich medium without fluconazole. On the other hand, some resistant isolates with gain-of-function mutations in MRR1 did not exhibit reduced fitness under these conditions. In a mouse model of disseminated candidiasis, three out of four tested fluconazole-resistant clinical isolates did not exhibit a significant fitness defect. However, all four fluconazole-resistant isolates were outcompeted by the matched susceptible isolates in a mouse model of gastrointestinal colonization, demonstrating that the effects of drug resistance on in vivo fitness depend on the host niche. Collectively, our results indicate that the fitness costs of drug resistance in C. albicans are not easily remediated, especially when proper control of gene expression is required for successful adaptation to life within a mammalian host. Copyright © 2017 American Society for Microbiology.

  6. Antibiotic Resistance Pattern of Staphylococcus aureus Strains Isolated from Personnel of Jahrom Hospitals in 2012

    Directory of Open Access Journals (Sweden)

    S Saadat

    2014-01-01

    Undo edits Methods: In this cross - sectional study, 397 of the anterior nasal samples of medical personnel and hospital services were collected by swab. The identification of S.aureus was determined by biochemical tests and microbiology, and the antibiotic resistances of isolates were determined by disk diffusion method for 13 antibiotics. In this method, the inhibition zone for methicillin-resistant strains was ≤ 10 mm the minimum inhibitory concentrations (MIC against antibiotic vancomycin, ticoplanin, linezolid and synercid were determined by E-test method. Results: In the present study, 11.3% of personals carried S. aureus in the nose. Among them, 90% were health care workers and 10% were health service workers. The most sensitivity was observed resistance to Ciprofloxacin, rifampin, linezolid and synercid (91.1%, but the lowest sensitivity was to penicillin (4.7%. of 9 MRSA strains, 1 strain was resistance to vancomycin and 2 strains were resistant to teicoplanin and linezolid. Conclusion: Because of S. aureus strains isolated from hospital staffs were resistant to most common antibiotics, identification and treatment of health care and health service workers can prevent nosocomial infections. Key words: Staphylococcu aureus carriers, hospital personnel, antibiotic resistance.

  7. New Ceftriaxone- and Multidrug-Resistant Neisseria gonorrhoeae Strain with a Novel Mosaic penA Gene Isolated in Japan.

    Science.gov (United States)

    Nakayama, Shu-Ichi; Shimuta, Ken; Furubayashi, Kei-Ichi; Kawahata, Takuya; Unemo, Magnus; Ohnishi, Makoto

    2016-07-01

    We have characterized in detail a new ceftriaxone- and multidrug-resistant Neisseria gonorrhoeae strain (FC428) isolated in Japan in 2015. FC428 differed from previous ceftriaxone-resistant strains and contained a novel mosaic penA allele encoding a new mosaic penicillin-binding protein 2 (PBP 2). However, the resistance-determining 3'-terminal region of penA was almost identical to the regions of two previously reported ceftriaxone-resistant strains from Australia and Japan, indicating that both ceftriaxone-resistant strains and conserved ceftriaxone resistance-determining PBP 2 regions might spread. Copyright © 2016, American Society for Microbiology. All Rights Reserved.

  8. Analysis of Clinical HIV-1 Strains with Resistance to Maraviroc Reveals Strain-Specific Resistance Mutations, Variable Degrees of Resistance, and Minimal Cross-Resistance to Other CCR5 Antagonists.

    Science.gov (United States)

    Flynn, Jacqueline K; Ellenberg, Paula; Duncan, Renee; Ellett, Anne; Zhou, Jingling; Sterjovski, Jasminka; Cashin, Kieran; Borm, Katharina; Gray, Lachlan R; Lewis, Marilyn; Jubb, Becky; Westby, Mike; Lee, Benhur; Lewin, Sharon R; Churchill, Melissa; Roche, Michael; Gorry, Paul R

    2017-12-01

    Maraviroc (MVC) is an allosteric inhibitor of human immunodeficiency virus type 1 (HIV-1) entry, and is the only CCR5 antagonist licensed for use as an anti-HIV-1 therapeutic. It acts by altering the conformation of the CCR5 extracellular loops, rendering CCR5 unrecognizable by the HIV-1 envelope (Env) glycoproteins. This study aimed to understand the mechanisms underlying the development of MVC resistance in HIV-1-infected patients. To do this, we obtained longitudinal plasma samples from eight subjects who experienced treatment failure with phenotypically verified, CCR5-tropic MVC resistance. We then cloned and characterized HIV-1 Envs (n = 77) from plasma of pretreatment (n = 36) and treatment failure (n = 41) samples. Our results showed variation in the magnitude of MVC resistance as measured by reductions in maximal percent inhibition of Env-pseudotyped viruses, which was more pronounced in 293-Affinofile cells compared to other cells with similar levels of CCR5 expression. Amino acid determinants of MVC resistance localized to the V3 Env region and were strain specific. We also observed minimal cross-resistance to other CCR5 antagonists by MVC-resistant strains. We conclude that 293-Affinofile cells are highly sensitive for detecting and measuring MVC resistance through a mechanism that is CCR5-dependent yet independent of CCR5 expression levels. The strain-specific nature of resistance mutations suggests that sequence-based diagnostics and prognostics will need to be more sophisticated than simple position scoring to be useful for managing resistance in subjects taking MVC. Finally, the minimal levels of cross-resistance suggests that recognition of the MVC-modified form of CCR5 does not necessarily lead to recognition of other antagonist-modified forms of CCR5.

  9. Antimicrobial edible apple films inactivate antibiotic resistant and susceptible Campylobacter jejuni strains on chicken breast

    Science.gov (United States)

    Campylobacter jejuni is the leading cause of bacterial diarrheal illness worldwide. Many strains are now becoming multi-drug resistant. To help overcome this problem, apple-based edible films containing carvacrol and cinnamaldehyde were evaluated for their effectiveness against antibiotic resistant...

  10. Mesoscopic Percolating Resistance Network in a Strained Manganite Thin Film

    KAUST Repository

    Lai, K.

    2010-07-08

    Many unusual behaviors in complex oxides are deeply associated with the spontaneous emergence of microscopic phase separation. Depending on the underlying mechanism, the competing phases can form ordered or random patterns at vastly different length scales. By using a microwave impedance microscope, we observed an orientation-ordered percolating network in strained Nd 1/2Sr1/2MnO3 thin films with a large period of 100 nanometers. The filamentary metallic domains align preferentially along certain crystal axes of the substrate, suggesting the anisotropic elastic strain as the key interaction in this system. The local impedance maps provide microscopic electrical information of the hysteretic behavior in strained thin film manganites, suggesting close connection between the glassy order and the colossal magnetoresistance effects at low temperatures.

  11. Mesoscopic percolating resistance network in a strained manganite thin film.

    Science.gov (United States)

    Lai, Keji; Nakamura, Masao; Kundhikanjana, Worasom; Kawasaki, Masashi; Tokura, Yoshinori; Kelly, Michael A; Shen, Zhi-Xun

    2010-07-09

    Many unusual behaviors in complex oxides are deeply associated with the spontaneous emergence of microscopic phase separation. Depending on the underlying mechanism, the competing phases can form ordered or random patterns at vastly different length scales. By using a microwave impedance microscope, we observed an orientation-ordered percolating network in strained Nd(1/2)Sr(1/2)MnO3 thin films with a large period of 100 nanometers. The filamentary metallic domains align preferentially along certain crystal axes of the substrate, suggesting the anisotropic elastic strain as the key interaction in this system. The local impedance maps provide microscopic electrical information of the hysteretic behavior in strained thin film manganites, suggesting close connection between the glassy order and the colossal magnetoresistance effects at low temperatures.

  12. Survival of Antibiotic Resistant and Antibiotic Sensitive Strains of E. coli O157 and E. coli O26 in Food Matrices.

    OpenAIRE

    Walsh, Ciara; Duffy, Geraldine; Blair, I. S.; McDowell, D. A.

    2006-01-01

    Escherichia coli O157:H7 or E. coli O26, which were AS (antibiotic sensitive), AR (laboratory created antibiotic resistant mutants), or naturally MAR (multi-antibiotic resistant), were inoculated into laboratory media, yoghurt or orange juice and their growth/survival monitored during enrichment at 37 °C or storage at 4 °C. The strains were also inoculated into minced beef and their thermal inactivation (D-values) examined at 55 °C, with and without a prior heat shock at 48 °C. The growth kin...

  13. Autosomal male determination in a spinosad-resistant housefly strain from Denmark

    DEFF Research Database (Denmark)

    Højland, Dorte H; Scott, Jeffrey G; Vagn Jensen, Karl-Martin

    2014-01-01

    BACKGROUND The housefly, Musca domestica L., is a global pest and has developed resistance to most insecticides applied for its control. The insecticide spinosad plays an important role in housefly control. Females of the Danish housefly strain 791spin are threefold more resistant to spinosad than...... males in this strain. The factor responsible for spinosad resistance in the strain is unknown, but previous studies suggest a role of cytochrome P450s for detoxification of spinosad. Sex determination in the housefly is controlled by a male-determining factor (M), either located on the Y chromosome...... or on one of the five autosomes (I to V). RESULTS The authors performed a series of crosses and backcrosses, starting with cross of 791spin and the susceptible reference strain aabys (bearing morphological mutations on each autosome). These flies were evaluated for gender and bioassayed to determine levels...

  14. Multiple antimicrobial resistance among Avian Escherichia coli strains in Albania

    Directory of Open Access Journals (Sweden)

    Antonio Camarda

    2010-01-01

    Full Text Available In this study, 101 Escherichia (E. coli isolates from broilers, laying hens and turkeys which had died from colibacillosis, collected from 37 intensive and rural farms in Albania, were tested for antimicrobial susceptibility toward 12 different molecules. The highest levels of resistance were observed for Erythromycin (E (100% Amoxicillin (AMX (99.1%, Tetracycline (TE 30 (96.07%, Streptomycin (STR (93.07% and Neomycin (N30 (85.15%. Considerable resistance was also detected for fluoroquinolones. Moreover, 73.33% of E. coli resistant to at least one fluoroquinolone were also resistant to the two other fluoroquinolones checked. No evident differences were found between the E. coli from intensive and from rural farms. Multiple antibiotic resistance was expressed by all the E. coli tested. 23.63% and 17.39% of E. coli isolated from intensive and rural farms, respectively, were resistant towards all the drugs tested. These data would seem to indicate incorrect use of antibiotics on poultry farms in Albania.

  15. Salmonella serovars and antimicrobial resistance in strains isolated from wild animals in captivity in Sinaloa, Mexico.

    Science.gov (United States)

    Silva-Hidalgo, Gabriela; López-Valenzuela, Martin; Juárez-Barranco, Felipe; Montiel-Vázquez, Edith; Valenzuela-Sánchez, Beatriz

    2014-08-01

    The aim of the present study was to evaluate the frequency of antibiotic resistance in Salmonella spp. strains from wild animals in captivity at the Culiacan Zoo and the Mazatlan Aquarium in Sinaloa, Mexico. We identified 17 different Salmonella enterica serovars at a prevalence of 19.90% (Culiacan Zoo) and 6.25% (Mazatlan Aquarium). Antibiotic sensitivity tests revealed that, of the 83 strains studied, 100% were multidrug resistant (MDR). The drugs against which the greatest resistance was observed were: penicillin, erythromycin, dicloxacillin, ampicillin, cephalothin, and chloramphenicol. We therefore conclude that MDR is common among Salmonella isolates originating from wild animals in captivity in Sinaloa.

  16. Bactericidal Efficacy of Allium sativum (garlic) Against Multidrug Resistant Vibrio cholerae O1 Epidemic Strains

    OpenAIRE

    Pramod Kumar; Jayprakash Yadav; Meenu Jain; Preeti Yadav; A.K. Goel; Pramod Kumar Yadava

    2016-01-01

    In recent years, emerging trend of antibiotic resistance in Vibrio cholerae associated with cholera epidemics is a matter of serious concern for the management of the disease. Indiscriminate use of antibiotics generally results in selection of antibiotic resistant strains. Introduction of newer antibiotics is a challenging task for the researchers as bacteria soon attain resistance. Therefore, identifying natural compounds of medicinal importance for control of cholera would be the best alter...

  17. Emergence of Staphylococcus aureus strains resistant to pristinamycin in Sfax (Tunisia).

    Science.gov (United States)

    Mezghani Maalej, S; Malbruny, B; Leclercq, R; Hammami, A

    2012-12-01

    We report the emergence of Staphylococcus aureus resistant to pristinamycin in Tunisia, and the characterization of the mechanisms of resistance to macrolides and streptogramins. Five strains of S. aureus resistant to pristinamycin were recovered from the department of dermatology in a Tunisian university hospital from skin samples after oral use of pristinamycin between 2004 and 2007. Susceptibility testing showed that all isolates were resistant to quinupristin-dalfopristin (MIC=4-32mg/L), lincomycin, gentamicin, kanamycin, tobramycin, tetracycline and rifampin. One isolate was susceptible to erythromycin. All five strains were closely related after analysis by pulsed-field gel electrophoresis. erm(C) was amplified from three strains and erm(A) from one strain. vga and vat genes were amplified from all strains. None of the isolates carried the vgb gene. The vga and vat genes were typed as vga(B) and vat(B) by restriction profiles analysis after electrophoresis. This is the first report of clonal emergence of S. aureus resistant to pristinamycin carrying vga and vat genes in Tunisia. The role of selective pressure of pristinamycin use is certainly the main explanation of this emergence. So we must reduce the utilisation of this antibiotic for the treatment of cutaneous and bone infectious disease caused by multidrug resistant bacteria. Copyright © 2012 Elsevier Masson SAS. All rights reserved.

  18. Trends in Antimicrobial Resistance in 1,968 Invasive Streptococcus pneumoniae Strains Isolated in Spanish Hospitals (2001 to 2003): Decreasing Penicillin Resistance in Children's Isolates

    Science.gov (United States)

    Oteo, Jesús; Lázaro, Edurne; de Abajo, Francisco J.; Baquero, Fernando; Campos, José

    2004-01-01

    To address the public health problem of antibiotic resistance, the European Union (EU) founded the European Antimicrobial Resistance Surveillance System. A network of 40 hospitals that serve approximately 30% of the Spanish population (about 12 million) participated. Each laboratory reported data on antimicrobial susceptibility testing using standard laboratory procedures that were evaluated by an external quality control program. The antibiotic consumption data were obtained from the National Health System. We compared the antibiotic susceptibility of Spanish isolates of invasive Streptococcus pneumoniae (2001 to 2003) with antibiotic consumption. Invasive S. pneumoniae was isolated from 1,968 patients, 20% of whom were children at or below the age of 14 years. Of non-penicillin-susceptible strains (35.6%; 95% confidence interval, 34 to 37.2), 26.4% were considered intermediate and 9.2% were considered resistant. Between 2001 and 2003, penicillin resistance decreased from 39.5 to 33% overall and from 60.4 to 41.2% in children at or below the age of 14 years (P = 0.002). Resistance to erythromycin was at 26.6%, and coresistance with penicillin was at 19.1%. Of total isolates, the ciprofloxacin MIC was >2 μg/ml for 2.1%, with numbers increasing from 0.4% (2001) to 3.9% (2003). Total antibiotic use decreased from 21.66 to 19.71 defined daily doses/1,000 inhabitants/day between 1998 and 2002. While consumption of broad-spectrum penicillins, cephalosporins, and erythromycin declined, use of amoxicillin-clavulanate and quinolones increased by 17.5 and 27%, respectively. The frequency of antibiotic resistance in invasive S. pneumoniae in Spain was among the highest in the EU. However, a significant decrease in penicillin resistance was observed in children. This decrease coincided with the introduction of a heptavalent conjugate pneumoccocal vaccine (June 2001) and with a global reduction in antibiotic consumption levels. PMID:15583283

  19. Heavy metal resistance by two bacteria strains isolated from a ...

    African Journals Online (AJOL)

    T3-03, were isolated from the biggest tailing in Asia-Dexing copper mine 4# tailing. The strain DX-T3-01 exhibited high tolerance to cadmium: 10 mM Cd2+ with yeast tryptophan peptone glucose (YTPG) agar plates and 18 mM in liquid ...

  20. Enhancement of bile resistance in Lactobacillus plantarum strains by soy lecithin.

    Science.gov (United States)

    Hu, B; Tian, F; Wang, G; Zhang, Q; Zhao, J; Zhang, H; Chen, W

    2015-07-01

    This study evaluated the effect of soy lecithin on the bile resistance of Lactobacillus plantarum. Six strains were cultured in MRS broth supplemented with soy lecithin at different concentrations. The strains incubated in MRS broth with 1·0% soy lecithin showed no inhibitory effect on cell growth. After culturing in MRS broth with 0·2-1·0% soy lecithin, the survival rate of harvested cells increased significantly (P Lactobacillus plantarum. Soy lecithin had no inhibitory effect on strain viability but significantly enhanced bile resistance. Surface hydrophobicity and cell integrity increased in strains cultured with soy lecithin. The observed shift in the cell fatty acid composition indicated changes to the cell membrane. As soy lecithin is safe for use in the food industry, its protective effects can be harnessed for the development of bile-sensitive strains with health-benefit functions for use in probiotic products. © 2015 The Society for Applied Microbiology.

  1. Effect of genetic strain and gender on age-related changes in body composition of the laboratory rat.

    Data.gov (United States)

    U.S. Environmental Protection Agency — Body composition data for common laboratory strains of rat as a function of age. This dataset is associated with the following publication: Gordon , C., K. Jarema ,...

  2. Caloric restriction in lean and obese strains of laboratory rat: effects on body composition, metabolism, growth and overall health

    Data.gov (United States)

    U.S. Environmental Protection Agency — Data related to obese and lean strains of rat commonly used in the laboratory that are calorically restricted and its effects on physiologic parameters (Body...

  3. Comparison of two multimetal resistant bacterial strains: Enterobacter sp. YSU and Stenotrophomonas maltophilia ORO2.

    Science.gov (United States)

    Holmes, Andrew; Vinayak, Anubhav; Benton, Cherise; Esbenshade, Aaron; Heinselman, Carlisle; Frankland, Daniel; Kulkarni, Samatha; Kurtanich, Adrienne; Caguiat, Jonathan

    2009-11-01

    The Y-12 plant in Oak Ridge, TN, which manufactured nuclear weapons during World War II and the Cold War, contaminated East Fork Poplar Creek with heavy metals. The multimetal resistant bacterial strain, Stenotrophomonas maltophilia Oak Ridge strain O2 (S. maltophilia O2), was isolated from East Fork Poplar Creek. Sequence analysis of 16s rDNA suggested that our working strain of S. maltophilia O2 was a strain of Enterobacter. Phylogenetic tree analysis and biochemical tests confirmed that it belonged to an Enterobacter species. This new strain was named Enterobacter sp. YSU. Using a modified R3A growth medium, R3A-Tris, the Hg(II), Cd(II), Zn(II), Cu(II), Au(III), Cr(VI), Ag(I), As(III), and Se(IV) MICs for a confirmed strain of S. maltophilia O2 were 0.24, 0.33, 5, 5, 0.25, 7, 0.03, 14, and 40 mM, respectively, compared to 0.07, 0.24, 0.8, 3, 0.05, 0.4, 0.08, 14, and 40 mM, respectively, for Enterobacter sp. YSU. Although S. maltophilia O2 was generally more metal resistant than Enterobacter sp. YSU, in comparison to Escherichia coli strain HB101, Enterobacter sp. YSU was resistant to Hg(II), Cd(II), Zn(II), Au(III), Ag(I), As(III), and Se(IV). By studying metal resistances in these two strains, it may be possible to understand what makes one microorganism more metal resistant than another microorganism. This work also provided benchmark MICs that can be used to evaluate the metal resistance properties of other bacterial isolates from East Fork Poplar Creek and other metal contaminated sites.

  4. [ISOLATION OF ANTIBIOTICS RESISTANCE GENES IN VIBRIO CHOLERAE O1 AND O139 SEROGROUP STRAINS].

    Science.gov (United States)

    Zadnova, S P; Smirnova, N I

    2015-01-01

    Determination of sensitivity of V. cholerae O1 serogroup El Tor biovar and O139 serogroup strains to antibiotics and determination of the presence of antibiotics resistance genes in their genome. The studies were carried out in 75 V. cholerae O1 and O139 serogroup strains. Sensitivity of cultures to antibiotics was determined by disc-diffusion method. DNA isolation was carried out in the presence of 6M guanidine thiocyanate. PCR was carried out in multi-channel amplificator Tercyc. A multiplex PCR was constructed, that includes 5 primer pairs for the detection of O1 and O139 serogroup resistance genes of vibrios to sulfame- thoxazolum, streptomycin B, trimethoprim, the presence of SXT element, an amplification program was developed. Using the developed PCR, V. cholerae O1 serogroup El Tor biovar strains with multiple drug resistance were established to be imported into Russia in 1993. The presence of SXT elements with genes of resistance to 4 antibiotics simultaneously was detected precisely in these strains, that belong to toxigenic genovariants of V. cholerae El Tor biovar. All the El Tor vibrio strains imported in the subsequent years were shown to stably preserve SXT element, this indicates its important role in biology of cholera vibrios. O139 serogroup strains with intact SXT element and having a deletion of the gene coding trimethoprim resistance were isolated. The data obtained may be used to establish molecular-genetic mechanisms of emergence of antibiotics resistant strains of cholera vibrio, construction of novel gene diagnostic test-systems and carrying out passportization of strains that are stored in the State collection of pathogenic bacteria.

  5. [Antibiotic resistance patterns of Escherichia coli strains isolated from urine cultures in Turkey: a meta-analysis].

    Science.gov (United States)

    Aykan, Sadiye Berna; Ciftci, Ihsan Hakkı

    2013-10-01

    those groups were significant in terms of ampicilin, amoxicillin-clavulanate, cefuroxime, ceftriaxone, trimethoprim-sulfamethoxazole, gentamicin, ciprofloxacin, amikacin and cefepime resistances (pantibiotic resistance patterns of E.coli strains isolated from urine cultures between 1996-2012 demonstrated significant variability, and many studies were based only on laboratory data. The results of this meta-analysis demonstrated that the resistance rates in commonly-used antibiotics for empirical therapy were high. In conclusion, information obtained by systematic evaluation of national data will be valuable for the determination of optimal antibiotic regimens and in prevention of unnecessary antibiotic use.

  6. Effect of genetic strain and gender on age-related changes in body composition of the laboratory rat.

    Science.gov (United States)

    Body composition data for common laboratory strains of rat as a function of age.This dataset is associated with the following publication:Gordon , C., K. Jarema , A. Johnstone , and P. Phillips. Effect of Genetic Strain and Gender on Age-Related Changes in Body Composition of the Laboratory Rat. Physiology & Behavior. Elsevier B.V., Amsterdam, NETHERLANDS, 153(1): 56-63, (2016).

  7. GC-MS-Based Metabonomic Profiling Displayed Differing Effects of Borna Disease Virus Natural Strain Hu-H1 and Laboratory Strain V Infection in Rat Cortical Neurons.

    Science.gov (United States)

    Liu, Siwen; Bode, Liv; Zhang, Lujun; He, Peng; Huang, Rongzhong; Sun, Lin; Chen, Shigang; Zhang, Hong; Guo, Yujie; Zhou, Jingjing; Fu, Yuying; Zhu, Dan; Xie, Peng

    2015-08-17

    Borna disease virus (BDV) persists in the central nervous systems of a wide variety of vertebrates and causes behavioral disorders. Previous studies have revealed that metabolic perturbations are associated with BDV infection. However, the pathophysiological effects of different viral strains remain largely unknown. Rat cortical neurons infected with human strain BDV Hu-H1, laboratory BDV Strain V, and non-infected control (CON) cells were cultured in vitro. At day 12 post-infection, a gas chromatography coupled with mass spectrometry (GC-MS) metabonomic approach was used to differentiate the metabonomic profiles of 35 independent intracellular samples from Hu-H1-infected cells (n = 12), Strain V-infected cells (n = 12), and CON cells (n = 11). Partial least squares discriminant analysis (PLS-DA) was performed to demonstrate discrimination between the three groups. Further statistical testing determined which individual metabolites displayed significant differences between groups. PLS-DA demonstrated that the whole metabolic pattern enabled statistical discrimination between groups. We identified 31 differential metabolites in the Hu-H1 and CON groups (21 decreased and 10 increased in Hu-H1 relative to CON), 35 differential metabolites in the Strain V and CON groups (30 decreased and 5 increased in Strain V relative to CON), and 21 differential metabolites in the Hu-H1 and Strain V groups (8 decreased and 13 increased in Hu-H1 relative to Strain V). Comparative metabonomic profiling revealed divergent perturbations in key energy and amino acid metabolites between natural strain Hu-H1 and laboratory Strain V of BDV. The two BDV strains differentially alter metabolic pathways of rat cortical neurons in vitro. Their systematic classification provides a valuable template for improved BDV strain definition in future studies.

  8. [Assessing the insecticide resistance of an Aedes aegypti strain in El Salvador].

    Science.gov (United States)

    Lazcano, Juan A Bisset; Rodríguez, María M; San Martín, José L; Romero, José E; Montoya, Romeo

    2009-09-01

    To assess the level of insecticide susceptibility of a certain Aedes aegypti strain found in El Salvador and to explain the mechanisms for its resistance to temephos. An A. aegypti strain from the municipality of Soyapango, Department of San Salvador, El Salvador, was studied. Bioassays were used to determine the susceptibility of the larvae to the organophosphate insecticide temephos and to three pyrethroids (deltamethrin, lambda-cyhalothrin, and cypermethrin); and of adults to an organophosphate insecticide (chlorpyrifos). The resistance factor (RF50) with determined with respect to a reference susceptible strain (Rockefeller). The mechanism of temephos resistance was determined through the use of synergistic substances, biochemical assays for enzymatic activity, and polyacrylamide gel zymograms. The larvae of the strain studied proved highly resistant to temephos (RF50 = 24.16). Of the enzyme samples analyzed, only the esterase A4 was linked to the mechanism of temephos resistance. The adult mosquitoes were susceptible to lambda-cyhalothrin and chlorpyrifos; and resistance to deltamethrin and cypermethrin fell into the category needing further verification. Temephos resistance could reduce the efficiency of chemical control of the A. aegypti mosquito in El Salvador study area. Chlorpyrifos, lambda-cyhalothrin, and cypermethrin are good alternative insecticides for use in new efforts to control this vector.

  9. Clinical laboratory detection of carbapenem-resistant and carbapenemase-producing Enterobacteriaceae.

    Science.gov (United States)

    Miller, Shelley; Humphries, Romney M

    2016-08-01

    Carbapenemases, enzymes that hydrolyze carbapenem-class antimicrobials, pose serious clinical and diagnostic challenges, including their recent rapid spread among members of the Enterobacteriaceae, a family with no inherent carbapenem resistance. Currently there is no one-size-fits-all method for detecting carbapenem-resistant Enterobacteriaceae (CRE) in the laboratory, nor how to differentiate carbapenemase-producers (CP) from isolates that are carbapenem-resistant via other or combined mechanisms. This article reviews definitions for CRE and CP-CRE, and discusses current phenotypic and molecular methods available to the clinical laboratory for the detection of both CP and non-CP CRE. Expert commentary: Routine evaluation of carbapenem resistance mechanism by the routine clinical laboratory are not necessary for patient care, as clinical breakpoints best predict response. However, evaluation for carbapenemase is integral to infection control efforts, and laboratories should have the capacity to do such testing, either in house or by submitting isolates to a reference laboratory.

  10. Local strain field engineering on interfacial thermal resistance of graphene nanoribbon

    Science.gov (United States)

    Xue, Yixuan; Chen, Yang; Cai, Kun; Liu, Zi-Yu; Zhang, Yingyan; Wei, Ning

    2018-01-01

    Strain engineering shows distinct advantages in thermal management by tuning thermal resistance in a wide range. Till now, most of the relative studies were concentrated in uniform deformation, wherein the effects of the localized strain field are rarely exploited. Herein, by using non-equilibrium molecular dynamics simulations, we explore the local strain field engineering effects on the interfacial thermal resistance (ITR) of graphene nanoribbons (GNRs). The model of GNRs employed in this work contains extended drag threads, which are used to create a local strain field. Our simulation results show that the ITR has a quasi-linear relationship with the local tensile strain. GNRs are very sensitive to the local strain field in terms of ITR with a maximum enhancement factor of ˜1.5 at the strain of 10%. The ITR is found to depend linearly on the local strain. This phenomenon is thoroughly explained by micro-structure deformation, heat flux scattering, and phonon density of state overlapping. Our findings here offer a simple yet useful tool in modulating the thermal properties of graphene and other two-dimensional materials by using local strain engineering.

  11. Laboratory evolution of a biotin-requiring Saccharomyces cerevisiae strain for full biotin prototrophy and identification of causal mutations

    NARCIS (Netherlands)

    Bracher, J.M.; de Hulster, A.F.; van den Broek, M.A.; Daran, J.G.; van Maris, A.J.A.; Pronk, J.T.

    2017-01-01

    Biotin prototrophy is a rare, incompletely understood, and industrially relevant characteristic of Saccharomyces cerevisiae strains. The genome of the haploid laboratory strain CEN.PK113-7D contains a full complement of biotin biosynthesis genes, but its growth in biotin-free synthetic medium is

  12. Biofilm Formation, Antimicrobial Resistance, and Sanitizer Tolerance of Salmonella enterica Strains Isolated from Beef Trim.

    Science.gov (United States)

    Wang, Rong; Schmidt, John W; Harhay, Dayna M; Bosilevac, Joseph M; King, David A; Arthur, Terrance M

    2017-12-01

    In the beef industry, product contamination by Salmonella enterica is a serious public health concern, which may result in human infection and cause significant financial loss due to product recalls. Currently, the precise mechanism and pathogen source responsible for Salmonella contamination in commercial establishments are not well understood. We characterized 89 S. enterica strains isolated from beef trim with respect to their biofilm-forming ability, antimicrobial resistance, and biofilm cell survival/recovery growth after sanitizer exposure. A total of 28 Salmonella serovars was identified within these strains. The most common serovars identified were Anatum, Dublin, Montevideo, and Typhimurium, with these accounting for nearly half of the total strains. The vast majority (86%) of the strains was able to develop strong biofilms, and the biofilm-forming ability was highly strain dependent and related to cell surface expression of extracellular polymeric structures. These strains also demonstrated strong tolerance to quaternary ammonium chloride (QAC) and chlorine dioxide (ClO 2 ), but were more sensitive to chlorine treatment. Sanitizer tolerance and bacterial postsanitization recovery growth were closely associated with strains' biofilm-forming ability. Thirty percent of the examined strains were found resistant to multiple antimicrobial agents and the resistance phenotypes were serovar associated, but not related to strains' biofilm-forming ability. Pulsed-field gel electrophoresis analysis tended to group strains by serovar rather than by biofilm-forming ability. Collectively, these data indicate that the strong biofilm formers of certain S. enterica strains/serovars possess significant potential for causing meat product contamination in meat processing environment.

  13. Convergent evolution toward an improved growth rate and a reduced resistance range in Prochlorococcus strains resistant to phage.

    Science.gov (United States)

    Avrani, Sarit; Lindell, Debbie

    2015-04-28

    Prochlorococcus is an abundant marine cyanobacterium that grows rapidly in the environment and contributes significantly to global primary production. This cyanobacterium coexists with many cyanophages in the oceans, likely aided by resistance to numerous co-occurring phages. Spontaneous resistance occurs frequently in Prochlorococcus and is often accompanied by a pleiotropic fitness cost manifested as either a reduced growth rate or enhanced infection by other phages. Here, we assessed the fate of a number of phage-resistant Prochlorococcus strains, focusing on those with a high fitness cost. We found that phage-resistant strains continued evolving toward an improved growth rate and a narrower resistance range, resulting in lineages with phenotypes intermediate between those of ancestral susceptible wild-type and initial resistant substrains. Changes in growth rate and resistance range often occurred in independent events, leading to a decoupling of the selection pressures acting on these phenotypes. These changes were largely the result of additional, compensatory mutations in noncore genes located in genomic islands, although genetic reversions were also observed. Additionally, a mutator strain was identified. The similarity of the evolutionary pathway followed by multiple independent resistant cultures and clones suggests they undergo a predictable evolutionary pathway. This process serves to increase both genetic diversity and infection permutations in Prochlorococcus populations, further augmenting the complexity of the interaction network between Prochlorococcus and its phages in nature. Last, our findings provide an explanation for the apparent paradox of a multitude of resistant Prochlorococcus cells in nature that are growing close to their maximal intrinsic growth rates.

  14. Convergent evolution toward an improved growth rate and a reduced resistance range in Prochlorococcus strains resistant to phage

    Science.gov (United States)

    Avrani, Sarit; Lindell, Debbie

    2015-01-01

    Prochlorococcus is an abundant marine cyanobacterium that grows rapidly in the environment and contributes significantly to global primary production. This cyanobacterium coexists with many cyanophages in the oceans, likely aided by resistance to numerous co-occurring phages. Spontaneous resistance occurs frequently in Prochlorococcus and is often accompanied by a pleiotropic fitness cost manifested as either a reduced growth rate or enhanced infection by other phages. Here, we assessed the fate of a number of phage-resistant Prochlorococcus strains, focusing on those with a high fitness cost. We found that phage-resistant strains continued evolving toward an improved growth rate and a narrower resistance range, resulting in lineages with phenotypes intermediate between those of ancestral susceptible wild-type and initial resistant substrains. Changes in growth rate and resistance range often occurred in independent events, leading to a decoupling of the selection pressures acting on these phenotypes. These changes were largely the result of additional, compensatory mutations in noncore genes located in genomic islands, although genetic reversions were also observed. Additionally, a mutator strain was identified. The similarity of the evolutionary pathway followed by multiple independent resistant cultures and clones suggests they undergo a predictable evolutionary pathway. This process serves to increase both genetic diversity and infection permutations in Prochlorococcus populations, further augmenting the complexity of the interaction network between Prochlorococcus and its phages in nature. Last, our findings provide an explanation for the apparent paradox of a multitude of resistant Prochlorococcus cells in nature that are growing close to their maximal intrinsic growth rates. PMID:25922520

  15. Comparison of antibiotic resistance patterns between laboratories in ...

    African Journals Online (AJOL)

    Antibiotic resistance is increasing rapidly and developing countries are the worse affected since they provide conditions and practices that support the development and spread of resistant microbes. For better health policy on antibiotic use a national surveillance program is needed to provide baseline data from different ...

  16. A new look at the drug-resistance investigation of uropathogenic E. coli strains.

    Science.gov (United States)

    Adamus-Białek, Wioletta; Lechowicz, Łukasz; Kubiak-Szeligowska, Anna B; Wawszczak, Monika; Kamińska, Ewelina; Chrapek, Magdalena

    2017-02-01

    Bacterial drug resistance and uropathogenic tract infections are among the most important issues of current medicine. Uropathogenic Escherichia coli strains are the primary factor of this issue. This article is the continuation of the previous study, where we used Kohonen relations to predict the direction of drug resistance. The characterized collection of uropathogenic E. coli strains was used for microbiological (the disc diffusion method for antimicrobial susceptibility testing), chemical (ATR/FT-IR) and mathematical (artificial neural networks, Ward's hierarchical clustering method, the analysis of distributions of inhibition zone diameters for antibiotics, Cohen's kappa measure of agreement) analysis. This study presents other potential tools for the epidemiological differentiation of E. coli strains. It is noteworthy that ATR/FT-IR technique has turned out to be useful for the quick and simple identification of MDR strains. Also, diameter zones of resistance of this E. coli population were compared to the population of E. coli strains published by EUCAST. We observed the bacterial behaviors toward particular antibiotics in comparison to EUCAST bacterial collections. Additionally, we used Cohen's kappa to show which antibiotics from the same class are closely related to each other and which are not. The presented associations between antibiotics may be helpful in selecting the proper therapy directions. Here we present an adaptation of interdisciplinary studies of drug resistance of E. coli strains for epidemiological and clinical investigations. The obtained results may be some indication in deciding on antibiotic therapy.

  17. High Virulence and Antifungal Resistance in Clinical Strains of Candida albicans

    Directory of Open Access Journals (Sweden)

    Eric Monroy-Pérez

    2016-01-01

    Full Text Available Antifungal resistance and virulence properties of Candida albicans are a growing health problem worldwide. To study the expression of virulence and azole resistance genes in 39 clinical strains of C. albicans, we used a model of infection of human vaginal epithelial cells with C. albicans strains isolated from Mexican women with vulvovaginal candidiasis (VVC. The strains were identified by PCR amplification of the ITS1 and ITS2 regions of rRNA. The detection and expression of virulence genes and azole resistance genes MDR1 and CDR1 were performed using PCR and RT-PCR, respectively. All strains were sensitive to nystatin and 38 (97.4% and 37 (94.9% were resistant to ketoconazole and fluconazole, respectively. ALS1, SAP4–SAP6, LIP1, LIP2, LIP4, LIP6, LIP7, LIP9, LIP10, and PLB1-PLB2 were present in all strains; SAP1 was identified in 37 (94.8% isolates, HWP1 in 35 (89.7%, ALS3 in 14 (35.8%, and CDR1 in 26 (66.6%. In nearly all of the strains, ALS1, HWP1, SAP4–SAP6, LIP1–LIP10, PLB1, and PLB2 were expressed, whereas CDR1 was expressed in 20 (51.3% and ALS3 in 14 (35.8%. In our in vitro model of infection with C. albicans, the clinical strains showed different expression profiles of virulence genes in association with the azole resistance gene CDR1. The results indicate that the strains that infect Mexican patients suffering from VVC are highly virulent and virtually all are insensitive to azoles.

  18. High prevalence of methicillin resistant staphylococci strains isolated from surgical site infections in Kinshasa.

    Science.gov (United States)

    Iyamba, Jean-Marie Liesse; Wambale, José Mulwahali; Lukukula, Cyprien Mbundu; za Balega Takaisi-Kikuni, Ntondo

    2014-01-01

    Surgical site infections (SSIs) after surgery are usually caused by Staphylococcus aureus and coagulase-negative staphylococci (CNS). In low income countries, methicillin resistant Staphylococcus aureus (MRSA) and methicillin resistant coagulase-negative staphylococci (MR-CNS) surgical site infections are particularly associated with high treatment cost and remain a source of mortality and morbidity. This study aimed to determine the prevalence and the sensitivity to antibiotics of MRSA and MR-CNS isolated from SSIs. Wound swabs were collected from 130 hospitalized surgical patients in two major hospitals of Kinshasa. S. aureus and CNS strains were identified by standard microbiological methods and latex agglutination test (Pastorex Staph-Plus). The antibiotic susceptibility of all staphylococcal strains was carried out using disk-diffusion method. Eighty nine staphylococcal strains were isolated. Out of 74 S. aureus and 15 CNS isolated, 47 (63.5%) and 9 (60%) were identified as MRSA and MR-CNS respectively. Among the MRSA strains, 47 strains (100%) were sensitive to imipenem, 39 strains (89%) to amoxycillin-clavulanic acid and 38 strains (81%) to vancomycin. All MR-CNS were sensitive to imipenem, amoxycillin-clavulanic acid and vancomycin. The isolated MRSA and MR-CNS strains showed multidrug resistance. They were both resistant to ampicillin, cotrimoxazole, erythromycin, clindamycin, ciprofloxacin, cefotaxime and ceftazidime. The results of the present study showed a high prevalence of MRSA and MR-CNS. Imipenem, amoxycillin-clavulanic acid and vancomycin were the most active antibiotics. This study suggests that antibiotic surveillance policy should become national priority as MRSA and MR-CNS were found to be multidrug resistant.

  19. Molecular diagnosis of pyrethroid resistance in Mexican strains of Boophilus microplus (Acari: Ixodidae).

    Science.gov (United States)

    Guerrero, Felix D; Li, Andrew Y; Hernandez, Ruben

    2002-09-01

    Polymerase chain reaction (PCR) diagnostic assays were used to identify possible resistance-associated roles of two amino acid substitutions found in pyrethroid resistance-associated genes of Boophilus microplus (Canestrini). Individual larvae from the San Felipe target site resistant strain and the Coatzacoalcos (Cz) metabolic resistant strain were separated into resistant and susceptible groups by larval packet bioassays and analyzed by PCR. A Phe --> Ile amino acid mutation in the sodium channel gene S6 transmembrane segment of domain III was found to have a close association with survival of acaricide treatments containing as high as 30% permethrin. As the permethrin dose was increased, an increase was seen in the proportion of surviving larvae that possessed two mutated sodium channel alleles. An Asp --> Asn amino acid substitution, originally found in high allele frequency in alleles of the CzEst9 esterase of the Cz strain, appeared to provide some resistance to permethrin. However, the presence of the mutation did not associate with resistance in the dose-response fashion seen with the sodium channel amino acid mutation. Resistance provided by CzEst9 might be more dependent on concentration of CzEst9 more so than the presence of a mutated allele.

  20. Mechanisms of strontium uptake by laboratory and brewing strains of Saccharomyces cerevisiae

    International Nuclear Information System (INIS)

    Avery, S.V.; Tobin, J.M.

    1992-01-01

    Concern over transfer of toxic metals from microorgansims to higher organisms and interest in the biotechnological potential of microorganisms for metal removal and/or recovery has increased interest in the processes involved in heavy metal uptake. Strontium is a trace element with no know essential biological role, but a long half-live and discharge as a constituent of radioactive wastewaters from nuclear reactors and in fall-out make its fate in the environment a concern. In this study, strontium uptake in biomass obtained from laboratory and industrial sources was examined. The mechanisms of Sr 2+ uptake were examined and uptake capacities for Sr 2+ were compared in both live and denatured forms of laboratory and brewery-derived strains of Saccharomyces cerevisiae. Release of cellular Ca 2+ , Mg 2+ , and H + in response to metabolism-independent and -dependent Sr 2+ uptake processes, was determined for all biomass types. The results indicate clear differences in the mechanisms of both Sr 2+ adsorption and intracellular Sr 2+ accumulation between the yeasts examined. They point out the strong influence that the differential ecophysiology of strains from a single genus may exert on metal uptake characteristics and on external binding and intracellular distribution of essential ions

  1. Baroreflex sensitivity differs among same strain Wistar rats from the same laboratory

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    Celso Ferreira

    2011-09-01

    Full Text Available Previous studies evidenced that a portion of normotensive Sprague–Dawley rats spontaneously exhibit lower baroreflex sensitivity, however, it was no yet investigated in Wistar rats. We aimed to compare baroreflex sensitivity among rats from the same strain and the same laboratory. Male Wistar normotensive rats (300-400g were studied. Cannulas were inserted into the abdominal aortic artery through the right femoral artery to measure mean arterial pressure and heart rate. Baroreflex was calculated as the derivative of the variation of heart rate in function of the mean arterial pressure variation (ΔHR/ΔMAP tested with a depressor dose of sodium nitroprusside (50 μg/kg and with a pressor dose of phenylephrine (8μg/kg in the right femoral venous approach through an inserted cannula. We divided the rats into four groups: i high bradycardic baroreflex, baroreflex gain less than -2 tested with phenylephrine; ii low bradycardic baroreflex, baroreflex gain between -1 and -2 tested with phenylephrine; iii high tachycardic baroreflex, baroreflex gain less than -3 tested with sodium nitroprusside; and iv low tachycardic baroreflex, baroreflex gain between -1 and -3 tested with sodium nitroprusside. Approximately 71% of the rats presented a decrease in bradycardic reflex while around half showed an increase in tachycardic reflex. No significant changes in basal mean arterial pressure and heart rate, tachycardic and bradycardic peak and heart rate range were observed. There was a significant change in baroreflex sensitivity among rats from the same strain and the same laboratory.

  2. Isolation and characterization of arsenic resistant Geobacillus kaustophilus strain from geothermal soils.

    Science.gov (United States)

    Cuebas, Mariola; Sannino, David; Bini, Elisabetta

    2011-08-01

    A thermophilic, arsenate resistant bacterial strain was isolated from a geothermal field located in the area surrounding Monterotondo (Tuscany, Italy). Based on 16S rRNA gene analysis and recN comparisons the strain was identified as Geobacillus kaustophilus. Cells of the strain, designated A1, were rod-shaped, 2-3 μm long and reacted negatively to Gram staining, despite its taxonomic classification as a Gram positive microorganism. Strain A1 is a thermophilic spore-forming bacterium, and grows optimally at pH 6.5 and 55 °C. An arsenate MIC of 80 mM was determined for strain A1, and the close relative G. kaustophilus DSM 7263(T) showed similar levels of arsenate resistance. These observations were consistent with the presence of arsenic detoxification genes in the genome of G. kaustophilus HTA426. Furthermore, strain A1 growth was not inhibited by 5 mM antimonite and 15 mM arsenite, the highest tested concentrations. This is the first description of arsenic resistance in a Geobacillus strain and supports the hypothesis that members of the genus may have a role in the biogeochemical cycling of arsenic. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  3. Increased transmission of Mycobacterium tuberculosis Beijing genotype strains associated with resistance to streptomycin: a population-based study.

    NARCIS (Netherlands)

    Buu, T.N.; Soolingen, D. van; Huyen, M.N.; Lan, N.T.; Quy, H.T.; Tiemersma, E.W.; Kremer, K.; Borgdorff, M.W.; Cobelens, F.G.

    2012-01-01

    BACKGROUND: Studies have shown that the Mycobacterium tuberculosis Beijing genotype is an emerging pathogen that is frequently associated with drug resistance. This suggests that drug resistant Beijing strains have a relatively high transmission fitness compared to other drug-resistant strains.

  4. Increased Transmission of Mycobacterium tuberculosis Beijing Genotype Strains Associated with Resistance to Streptomycin: A Population-Based Study

    NARCIS (Netherlands)

    Buu, Tran N.; van Soolingen, Dick; Huyen, Mai N. T.; Lan, Nguyen T. N.; Quy, Hoang T.; Tiemersma, Edine W.; Kremer, Kristin; Borgdorff, Martien W.; Cobelens, Frank G. J.

    2012-01-01

    Background: Studies have shown that the Mycobacterium tuberculosis Beijing genotype is an emerging pathogen that is frequently associated with drug resistance. This suggests that drug resistant Beijing strains have a relatively high transmission fitness compared to other drug-resistant strains.

  5. Association between genotype and drug resistance profiles of Mycobacterium tuberculosis strains circulating in China in a national drug resistance survey

    NARCIS (Netherlands)

    Zhou, Yang; van den Hof, Susan; Wang, Shengfen; Pang, Yu; Zhao, Bing; Xia, Hui; Anthony, Richard; Ou, Xichao; Li, Qiang; Zheng, Yang; Song, Yuanyuan; Zhao, Yanlin; van Soolingen, Dick

    2017-01-01

    We describe the population structure of a representative collection of 3,133 Mycobacterium tuberculosis isolates, collected within the framework of a national resistance survey from 2007 in China. Genotyping data indicate that the epidemic strains in China can be divided into seven major complexes,

  6. Biofilm Formation Potential of Heat-Resistant Escherichia coli Dairy Isolates and the Complete Genome of Multidrug-Resistant, Heat-Resistant Strain FAM21845.

    Science.gov (United States)

    Marti, Roger; Schmid, Michael; Kulli, Sandra; Schneeberger, Kerstin; Naskova, Javorka; Knøchel, Susanne; Ahrens, Christian H; Hummerjohann, Jörg

    2017-08-01

    We tested the biofilm formation potential of 30 heat-resistant and 6 heat-sensitive Escherichia coli dairy isolates. Production of curli and cellulose, static biofilm formation on polystyrene (PS) and stainless steel surfaces, biofilm formation under dynamic conditions (Bioflux), and initial adhesion rates (IAR) were evaluated. Biofilm formation varied greatly between strains, media, and assays. Our results highlight the importance of the experimental setup in determining biofilm formation under conditions of interest, as correlation between different assays was often not a given. The heat-resistant, multidrug-resistant (MDR) strain FAM21845 showed the strongest biofilm formation on PS and the highest IAR and was the only strain that formed significant biofilms on stainless steel under conditions relevant to the dairy industry, and it was therefore fully sequenced. Its chromosome is 4.9 Mb long, and it harbors a total of five plasmids (147.2, 54.2, 5.8, 2.5, and 1.9 kb). The strain carries a broad range of genes relevant to antimicrobial resistance and biofilm formation, including some on its two large conjugative plasmids, as demonstrated in plate mating assays. IMPORTANCE In biofilms, cells are embedded in an extracellular matrix that protects them from stresses, such as UV radiation, osmotic shock, desiccation, antibiotics, and predation. Biofilm formation is a major bacterial persistence factor of great concern in the clinic and the food industry. Many tested strains formed strong biofilms, and especially strains such as the heat-resistant, MDR strain FAM21845 may pose a serious issue for food production. Strong biofilm formation combined with diverse resistances (some encoded on conjugative plasmids) may allow for increased persistence, coselection, and possible transfer of these resistance factors. Horizontal gene transfer may conceivably occur in the food production setting or the gastrointestinal tract after consumption. Copyright © 2017 Marti et al.

  7. Determination of tetracycline resistance genes in Vibrio cholerae O1 biotype El Tor serotype Inaba strains isolated from outbreaks occurred in Iran in 2013

    Directory of Open Access Journals (Sweden)

    Azin Khany

    2016-05-01

    Full Text Available V. cholerae is the causative agent of potentially life threatening diarrheal disease named as cholera. Cholera is an endemic disease in Iran. Encountered increasing resistance of V. cholerae to commonly used antibiotics such as tetracycline has led to major challenges in the treatment of this disease .The present study was carried out to determine the prevalence of drug resistance as well as molecular bases of resistant V.cholerae strains which were isolated from patients in cholera outbreaks during summer of 2013 in Iran. Susceptibly testing was performed on V.cholerae strains isolated from stool of patients suffering from cholera in Iranian reference health laboratory by E -test MIC method as recommended by CLSI guideline. Antibiotic strips used included Ampicillin, Ciprofloxacin, Nalidixic acid, Cefixime , Tetracycline, Erythromycin and Trimethoprim-sulfamethoxazole .Regarding observed dominant pattern of tetracycline resistance comparing to results of previous years ,we decided to confirm the resistance by detecting the tetA , tetB and tetC by Polymerase chain reaction method. The results of antibiotic susceptibility testing revealed 100% resistance of isolated strains to tetracycline. Data obtained from PCR reaction on resistant strains for tetA, tetB and tetC showed that 45(44.1%, 37(36.2% and 70(68.6% were containing tetA, tetB and tetC gene respectively. Moreover, the frequency of tetA+tetB, tetA+C, tetB+tetC , tetA+tetB+tetC also were determined as 9(8.8%, 32(31.3%, 19(18.6% and 8(7.8% respectively. This study revealed the pattern of drug resistance distribution of isolates harboring tetA, tetB, tetC genes in relation to sex, age and nationality of patients and the cities where the cases were reported. A significant correlation was obtained between reported geographical incidence and drug resistant strains.

  8. Strain Localization and Weakening Processes in Viscously Deforming Rocks: Numerical Modeling Based on Laboratory Torsion Experiments

    Science.gov (United States)

    Doehmann, M.; Brune, S.; Nardini, L.; Rybacki, E.; Dresen, G.

    2017-12-01

    Strain localization is an ubiquitous process in earth materials observed over a broad range of scales in space and time. Localized deformation and the formation of shear zones and faults typically involves material softening by various processes, like shear heating and grain size reduction. Numerical modeling enables us to study the complex physical and chemical weakening processes by separating the effect of individual parameters and boundary conditions. Using simple piece-wise linear functions for the parametrization of weakening processes allows studying a system at a chosen (lower) level of complexity (e.g. Cyprych et al., 2016). In this study, we utilize a finite element model to test two weakening laws that reduce the strength of the material depending on either the I) amount of accumulated strain or II) deformational work. Our 2D Cartesian models are benchmarked to single inclusion torsion experiments performed at elevated temperatures of 900 °C and pressures of up to 400 MPa (Rybacki et al., 2014). The experiments were performed on Carrara marble samples containing a weak Solnhofen limestone inclusion at a maximum strain rate of 2.0*10-4 s-1. Our models are designed to reproduce shear deformation of a hollow cylinder equivalent to the laboratory setup, such that material leaving one side of the model in shear direction enters again on the opposite side using periodic boundary conditions. Similar to the laboratory tests, we applied constant strain rate and constant stress boundary conditions.We use our model to investigate the time-dependent distribution of stress and strain and the effect of different parameters. For instance, inclusion rotation is shown to be strongly dependent on the viscosity ratio between matrix and inclusion and stronger ductile weakening increases the localization rate while decreasing shear zone width. The most suitable weakening law for representation of ductile rock is determined by combining the results of parameter tests with

  9. Analysis of antibiotic resistance pattern of S. aureus strains isolated from the Orthopedics-Traumatology Section of "Sf. Spiridon" Clinical Emergency Hospital, Iaşi.

    Science.gov (United States)

    Tucaliuc, D; Alexa, O; Tuchiluş, Cristina Gabriela; Ursu, Ramona Gabriela; Tucaliuc, Elena Simona; Iancu, Luminiţa Smaranda

    2014-01-01

    The retrospective analysis of antibiotic sensibility of S. aureus strains isolated from infected patients from the Orthopedics-Traumatology Clinic of "Sf. Spiridon" Clinical Emergency Hospital, Iaşi during January 2003-December 2013, in view of determining the evolution trend of the resistance phenomenon and of pinpointing the most useful treatment for these strains. The antibiotic sensitivity test was carried out using two methods: diffusimetric-Kirby-Bauer and the MIC determination by E-test (for the strains isolated in 2013); the interpretation of the sensitivity was made in a standardized manner, in compliance with the CLSI (Clinical and Laboratory Standards Institute) standard for antibiotics testing in force. The sensitivity testing for beta-lactams proved that during the 11 years of the study, the average value of the frequency of resistant strains was of 41.59% +/- 8.68. The highest frequency of MRSA (Methicillin Restant S. aureus) strains was noticed in 2012 (58.6%), followed by 2004 (50.7%). Even if in 2013 it dropped to 38.9%, the trend calculated for 2003-2013 is slightly rising (y = 0.0073x + 0.372). Out of the total of 495 S. aureus strains that were isolated, 164 (33.13%) were completely sensitive to the tested antibiotics and 26 (5.25%) were resistant only to beta-lactams. The other MRSA strains associated multiple resistance and MIC for vancomycin varied between 0.5-2 mg/ml. Two strains whose MIC was of 0.5 mg/ml were sensitive to most classes of tested antibiotics, including beta-lactams, except for macrolides (erythromycin), and the strain whose MIC was of 2 mg/ml, was resistant to all classes of tested antibiotics, except for glycopeptides and oxazolidiones. The other tested strains had a MIC for vancomycin equal to 1 mg/ml. Due to the fact that there are infections with SAMR strains in a rather worrying percentage (53.9%) that are resistant to the other classes of antibiotics, the only therapeutic solution being the vancomycin treatment, its

  10. Isolation, identification and antibiotic resistance of Campylobacter strains isolated from domestic and free-living pigeons.

    Science.gov (United States)

    Dudzic, A; Urban-Chmiel, R; Stępień-Pyśniak, D; Dec, M; Puchalski, A; Wernicki, A

    2016-04-01

    1. The aim of this study was to evaluate the occurrence of Campylobacter spp. in domestic and free-living pigeons and to evaluate the antibiotic resistance profiles. 2. The material consisted of cloacal swabs obtained from 108 homing pigeons and fresh faeces from 72 wild birds from Lublin and its vicinity. The identification of strains isolated on differential/selective media for Campylobacter spp. was carried out by MALDI-TOF and PCR. The susceptibility to antibiotics was evaluated by minimum inhibitory concentration (MIC) in Mueller-Hinton broth. 3. A total of 35 strains of Campylobacter spp. were isolated; 27 were identified as Campylobacter jejuni and 8 as Campylobacter coli. Over half of the isolates were resistant to erythromycin and streptomycin, 40% of strains were resistant to tetracycline and ampicillin and 37% isolates were resistant to amoxicillin. Resistance to two or more antibiotics was observed in all strains tested. 4. The results indicate that both domestic and free-living pigeons are reservoirs for bacteria of the genus Campylobacter, which are characterised by varied and growing resistance to commonly used antibiotics.

  11. Plasmodium vinckei: selection of a strain exhibiting stable resistance to arteether.

    Science.gov (United States)

    Puri, S K; Chandra, Ramesh

    2006-10-01

    A strain of rodent malaria parasite Plasmodium vinckei showing >12-fold resistance to arteether has been selected after exposure to sub-curative doses of drug in 44 sequential passages over a period of 700 days. Experimentally induced resistance was found to be stable after drug free maintenance of parasites for 11 serial passages over a period of 100 days. Cross-sensitivity studies have shown that apart form resistance to related derivatives like artemether and artesunic acid, the derived parasites also show resistance to quinine and mefloquine.

  12. Inhibition of lipase activity in antibiotic-resistant propionibacterium acnes strains.

    Science.gov (United States)

    Gloor, M; Wasik, B; Becker, A; Höffler, U

    2002-01-01

    Erythromycin-sensitive and/or clindamycin-sensitive strains of Propionibacterium acnes show a reduced lipase production at levels below the minimal growth-inhibitory concentration (MIC). The objective of this study was to determine whether erythromycin and clindamycin concentrations far below the MIC inhibit lipase production in P. acnes strains resistant to these antibiotics. Of 42 P. acnes strains, 10 showed an MIC >256 micro g/ml for erythromycin. Two strains showed MICs of 0.19 and 0.25 micro g/ml, while the MIC of the remaining strains was Lipase activity was determined up to a concentration of 192 micro g/ml by cultivation on spirit blue agar + lipase reagent. The 10 strains whose erythromycin MIC was >256 micro g/ml were also tested for lipase inhibition by clindamycin. While this method fails to differentiate between inhibition of lipase production and inhibition of lipase activity, the absence of inhibition of lipase activity rules out inhibition of lipase production. Inhibition of lipolysis by sub-MIC concentrations was demonstrated only for clindamycin in 3 P. acnes strains. However, lipase inhibition was seen only at the dilution level immediately below the MIC. Resistant P. acnes strains with high erythromycin and/or clindamycin MICs can be ruled out to show in vitro inhibition of lipase production at antibiotic concentrations far below the MIC. Copyright 2002 S. Karger AG, Basel

  13. Isolation and Characterization of Agrobacterium Strains from Soil: A Laboratory Capstone Experience

    Directory of Open Access Journals (Sweden)

    Kim R. Finer

    2016-12-01

    Full Text Available In this investigation, the students’ goal was to isolate and characterize Agrobacterium strains from soil. Following selection and enrichment on 1A-t medium, putative Agrobacterium isolates were characterized by Gram stain reaction and biochemical tests. Isolates were further evaluated using polymerase chain reaction (PCR with different primer sets designed to amplify specific regions of bacterial deoxyribonucleic acid (DNA. Primer sets included AGRH to identify isolates that were members of the Rhizobiaceae, BIOVAR1 primers to identify members of Agrobacterium biovar group I, and a third set, VIRG, to determine presence of virG (only present in pathogenic Agrobacterium strains. During the investigation, students applied previously learned techniques including serial dilution, use of selective/differential media, staining protocols, biochemical analysis, molecular analysis via PCR, and electrophoresis. Students also gained practical experience using photo documentation to record data for an eventual mock journal publication of the capstone laboratory experience. Pre- and post-evaluation of class content knowledge related to the techniques, protocols, and learning objectives of these laboratories revealed significant learning gains in the content areas of Agrobacterium–plant interactions (p ≤ 0.001 and molecular biology (p ≤ 0.01. The capstone journal assignment served as the assessment tool to evaluate mastery and application of laboratory technique, the ability to accurately collect and evaluate data, and critical thinking skills associated with experimental troubleshooting and extrapolation. Analysis of journal reports following the capstone experience showed significant improvement in assignment scores (p ≤ 0.0001 and attainment of capstone experience learning outcomes.

  14. Balancing ballistic protection against physiological strain: evidence from laboratory and field trials.

    Science.gov (United States)

    Taylor, Nigel A S; Burdon, Catriona A; van den Heuvel, Anne M J; Fogarty, Alison L; Notley, Sean R; Hunt, Andrew P; Billing, Daniel C; Drain, Jace R; Silk, Aaron J; Patterson, Mark J; Peoples, Gregory E

    2016-02-01

    This project was based on the premise that decisions concerning the ballistic protection provided to defence personnel should derive from an evaluation of the balance between protection level and its impact on physiological function, mobility, and operational capability. Civilians and soldiers participated in laboratory- and field-based studies in which ensembles providing five levels of ballistic protection were evaluated, each with progressive increases in protection, mass (3.4-11.0 kg), and surface-area coverage (0.25-0.52 m(2)). Physiological trials were conducted on volunteers (N = 8) in a laboratory, under hot-dry conditions simulating an urban patrol: walking at 4 km·h(-1) (90 min) and 6 km·h(-1) (30 min or to fatigue). Field-based trials were used to evaluate tactical battlefield movements (mobility) of soldiers (N = 31) under tropical conditions, and across functional tests of power, speed, agility, endurance, and balance. Finally, trials were conducted at a jungle training centre, with soldiers (N = 32) patrolling under tropical conditions (averaging 5 h). In the laboratory, work tolerance was reduced as protection increased, with deep-body temperature climbing relentlessly. However, the protective ensembles could be grouped into two equally stressful categories, each providing a different level of ballistic protection. This outcome was supported during the mobility trials, with the greatest performance decrement evident during fire and movement simulations, as the ensemble mass was increased (-2.12%·kg(-1)). The jungle patrol trials similarly supported this outcome. Therefore, although ballistic protection does increase physiological strain, this research has provided a basis on which to determine how that strain can be balanced against the mission-specific level of required personal protection.

  15. Comparative molecular study of Mycobacterium tuberculosis strains, in times of antimicrobial drug resistance

    Directory of Open Access Journals (Sweden)

    G. Varela

    2005-03-01

    Full Text Available Strains of Mycobacterium tuberculosis were compared using two DNA fingerprinting techniques: Restriction Fragment Length Polymorphism (RFLP and Double-Repetitive-Element-PCR (DRE-PCR. Two of these strains: IH1 (susceptible to isoniazid and IH2 (resistant to isoniazid were recovered from cases of pulmonary tuberculosis which occurred in two brothers who lived together. The first one was recognized on July 1999, and the second was diagnosed one year later. IH1 and IH2 showed the same pattern of bands with both molecular tests. These results suggest that single drug chemoprophylaxis may occasionally select resistant strains for that drug, which can eventually cause disease and be recognized through these tests. Strains IH3, IH4 and IH5 were obtained from sputum samples of 3 different patients, and intra-laboratory cross-contamination was suspected when it was realized that the 3 positive materials had been consecutively processed the same day by the same worker in the same biological safety cabinet. Again, the 3 strains revealed identical band patterns with RFLP and DRE-PCR, confirming the posed suspicion. The results with DRE-PCR were obtained after only 8 hours of work, without the need for subcultures. This procedure allows quick correction of treatment conducts, avoiding unnecessary exposure of people and bacteria to antimicrobial drugs.Se compararon cepas de Mycobacterium tuberculosis utilizando 2 procedimientos de ADN fingerprinting: polimorfismo de los fragmentos de restricción (RFLP y Double-Repetitive-Element-PCR (DRE-PCR. Dos de las cepas: IH1 (susceptible a isoniazida e IH2 (resistente a isoniazida se recuperaron a partir de casos de tuberculosis pulmonar que ocurrieron en dos hermanos convivientes. La primera fue aislada en julio de 1999 y la segunda un año después. IH1 e IH2 mostraron el mismo patrón de bandas por ambos procedimientos. Estos resultados sugieren que la quimioprofilaxis con una sola droga puede ocasionalmente

  16. Compatibility and competitiveness of a laboratory strain of Anastrepha Fraterculus (Diptera: Tephritidae) after irradiation treatment

    International Nuclear Information System (INIS)

    Allinghi, A.; Calcagno, G.; Gomez Cendra, P.; Vilardi, J.C.; Petit-Marty, N.; Segura, D.; Cladera, J.; Vera, T.; Gramajo, C.; Willink, E.

    2007-01-01

    We evaluated under semi-natural field cage conditions sexual compatibility and competitiveness of a laboratory strain (LAB) compared to a wild population (TUC) of Anastrepha fraterculus (Wiedemann). The LAB strain is produced under semi-mass rearing conditions at the Estacion Experimental Agroindustrial Obispo Colombres facility (Tucuman, Argentina). Wild flies were obtained at Horco Molle (Tucuman, Argentina) from infested guava fruits. LAB pupae were irradiated ( 60 Co) 48 h before adult emergence. The tested doses were 0 (control), 40, 70, and 100 Gy. Twenty-five males and 25 females each of TUC and LAB were released into cages and mating pairs collected. Only 1 irradiation dose was considered at a time. Females were separated and allowed to lay eggs into artificial fruits to estimate induced sterility from the corresponding hatching rate. Copulation start time did not differ significantly between strains nor among irradiation treatments. Copulation duration showed highly significant differences among irradiation doses, but no differences between strains. The index of sexual isolation (ISI) and the relative sterility index (RSI) indices indicated that LAB and TUC are fully compatible, males from TUC and LAB did not differ in mating competitiveness, and irradiation within the range tested did not affect these indices. Non-irradiated LAB females exhibited higher mating propensity than TUC ones. However, a significant reduction in the female relative performance index (FRPI) index was observed with increasing irradiation dose. The analysis of induced sterility indicated that treatment with 40 Gy reduces male fertility from about 80% to 0.75%, and higher doses produce total sterility. In females, the 40 Gy dose reduces fertility to about 2% and higher doses prevent egg laying. (author) [es

  17. Phenotypic and Genotypic Antimicrobial Resistance of Lactococcus Sp. Strains Isolated from Rainbow Trout (Oncorhynchus Mykiss

    Directory of Open Access Journals (Sweden)

    Ture Mustafa

    2015-04-01

    Full Text Available A current profile of antimicrobial resistance and plasmid of 29 Lactococcus garvieae and one Lactococcus lactis strains isolated from rainbow trouts (Oncorhynchus mykiss from farms throughout Turkey were investigated. All isolates were sensitive to penicillin G (90%, ampicillin (86.7%, florfenicol (83.3%, amoxicillin (80.1%, and tetracycline (73.4%, and resistant to trimethoprim+sulfamethoxazole (86.6% and gentamycin (46.6% by disc diffusion method. Twenty-eight (93% isolates had two to seven antibiotic resistance genes (ARGs determined by PCR. The most prevalent ARGs were tetracycline (tetB, erythromycin (ereB, and β-lactam (blaTEM. Bacterial strains were also screened for plasmid DNA by agarose gel electrophoresis and two strains harboured plasmids, with sizes ranging from 3 to 9 kb.

  18. Aciclovir resistance among indian strains of Herpes simplex virus as determined using a dye uptake assay

    Directory of Open Access Journals (Sweden)

    Abraham A

    2007-01-01

    Full Text Available Resistance to aciclovir (ACV among Herpes simplex virus (HSV isolates is increasingly being reported in the literature particularly in immunocompromised patients. However, there is only limited data available from India despite widespread use of ACV in our hospital. A cross-sectional study was hence conducted to determine the aciclovir (ACV susceptibility of HSV 1 and 2 isolates using a dye uptake (DU assay. This study showed a 3.0% prevalence of ACV resistance among HSV-1 strains (2/66, median IC 50 0.098 µg/mL while in HSV-2 strains, it was 7.8% (5/64, median IC 50 0.195 µg/mL. The IC 50 for the HSV-1 and HSV-2 strains resistant to ACV was greater than or equal to 6.25 µg/mL.

  19. [Establishment of 5 resistant ovarian cancer cell strains and expression of resistance-related genes].

    Science.gov (United States)

    Luan, Ying-zi; Li, Li; Li, Dang-rong; Zhang, Wei; Tang, Bu-jian

    2004-06-01

    To investigate expression difference of several drug resistance related genes between sensitive and resistant ovarian carcinoma cells. Cell lines resistant to cisplatin, carboplatin and taxol were established from ovarian carcinoma cell lines of SKOV3 and A2780, and their biological features were detected. The expressions of several genes related to drug resistance were measured by RT-PCR method. (1) The values of resistance index (RI) of resistant cells to relevant drugs were elevated 3 times or more, with different degrees of cross-resistance to several other drugs (RI 2 approximately 20). They grew more slowly than primary cells (Td elongated 1.4 approximately 2.4 times, P 0.05). Intracellular concentrations of relevant drugs were reduced 2.0 approximately 8.5 times in resistant cells (P p53, lung resistance protein-1 (LRP-1), multiple drug resistance related protein-1 (MRP-1) genes were expressed at lower levels in resistant cells than in sensitive cells; while protein kinase C (PKC), topoisomerase (topo) I, and topo II beta were expressed higher, no obvious alterations were found concerning glutathione S transferase-pi (GST-pi), and topo II alpha. Expression of multiple drug resistance-1 (MDR-1) gene was either elevated or reduced in different cells. The expressions of resistance related genes were widely different in different kinds of resistant cells, suggesting more than one pathway leading to resistance transformation. This adds more difficulties for clinical management.

  20. [Isolation of a carbapenem-resistant K1 serotype Klebsiella pneumonia strain and the study of resistance mechanism].

    Science.gov (United States)

    Zhang, Rong; Wang, Xuan; Lü, Jianxin

    2014-12-16

    To study the virulence and mechanism of carbapenem resistance of a clinical isolate of carbapenem-resistant K1 serotype Klebsiella pneumonia strain. Identification of isolate was carried out with VITEK-2 compact system. Antimicrobial susceptibility was determined by E-test; Metallo β-lactamases and carbapenemases screening were conducted by imipenem-EDTA double disc synergy test and modified Hodge test, respectively.Specific polymerehse chain reaction (PCR) and DNA sequencing were preformed to detect the virulence genes including K1, K2, K5, K20, K54, K57, magA, rmpA, wcaG and a series of β-lactamase resistence genes. Conjunction experiment was also performed. The plasmids of transconjugants were submitted to PCR-based replicon typing (PBRT) method. Molecular typing was performed by multilocus sequence typing (MLST). Antimicrobial susceptibility testing revealed that the Klebsiella pneumonia strain was resistant to most of the antibiotics used in clinic. Phynotype confirmary rest revealed the production of carbapanemases, while Metallo β-lactamases were negative; PCR and DNA sequencing confirmed the isolate was positive for blaKPC-2, blaCTX-M-15, blaTEM-1, blaSHV-1 and virulence genes K1, magA, rmpA, wcaG simultaneously; blaKPC-2 was transferred from donor to Escherichia EC600 by conjunction experiment, while no virulence genes were found in the transconjugants. PBRT revealed that Frep plasmid was found in transconjugants. MLST analysis revealed that this strain belonged to ST23. K1 serotype Klebsiella pneumonia strain carries virulence genes and carbapenem resistance gene blaKPC-2, noteworthily the carbapenem resistance genes can be transferred through horizontal transmission on plasmids.

  1. Comparison of drug sensitivity and genotypes of clinically isolated strains of levofloxacin-resistant Streptococcus pneumoniae obtained from Okinawa Island, the Japanese main island and Hong Kong.

    Science.gov (United States)

    Sunagawa, Satoko; Fujita, Jiro; Higa, Futoshi; Tateyama, Masao; Haranaga, Shusaku; Nakasone, Isamu; Yamane, Nobuhisa; Uno, Tsukasa

    2011-08-01

    The prevalence of fluoroquinolone-resistant Streptococcus pneumoniae is increasing worldwide. In the present study, a comparison of drug sensitivity and genotypes of clinically isolated strains of levofloxacin (LVFX)-resistant S. pneumoniae obtained from Hong Kong, Okinawa Island and the Japanese main island (Honshu) was performed. MICs of quinolones (LVFX, tosufloxacin, ciprofloxacin, gatifloxacin and sitafloxacin (STFX)) and other antibiotics (penicillin G, cefcapene, cefditoren, clarithromycin and azithromycin) were determined by a microdilution broth method according to the Clinical and Laboratory Standards Institute Standards. The quinolone-resistance determining regions (QRDRs) of gyrA, gyrB, parC and parE of these strains were analyzed by PCR-based sequencing. All 40 strains tested had more than one amino-acid substitution in the QRDRs of gyrA, gyrB, parC or parE. Although there seemed to be some clonality in strains obtained from Hong Kong, there was no clonality in strains obtained from Okinawa and Japan. Strains obtained from Hong Kong, Okinawa Island and the Japanese main island were genetically different by pulsed-field gel electrophoresis analysis. The range of MIC values of STFX against isolates resistant to LVFX (MIC 4-32 mg l(-1)) was 0.12-0.5 mg l(-1), and MIC(80) values of STFX against LVFX-resistant isolates were 0.25 mg l(-1). This study suggests that LVFX-resistant S. pneumoniae is similar in all three locations and STFX is potent against LVFX-resistant S. pneumoniae with multiple mutations in QRDRs of gyrase A and topoisomerase IV.

  2. Strain-Specific Transfer of Antibiotic Resistance from an Environmental Plasmid to Foodborne Pathogens

    Directory of Open Access Journals (Sweden)

    Eva Van Meervenne

    2012-01-01

    Full Text Available Pathogens resistant to multiple antibiotics are rapidly emerging, entailing important consequences for human health. This study investigated if the broad-host-range multiresistance plasmid pB10, isolated from a wastewater treatment plant, harbouring amoxicillin, streptomycin, sulfonamide, and tetracycline resistance genes, was transferable to the foodborne pathogens Salmonella spp. or E. coli O157:H7 and how this transfer alters the phenotype of the recipients. The transfer ratio was determined by both plating and flow cytometry. Antibiotic resistance profiles were determined for both recipients and transconjugants using the disk diffusion method. For 14 of the 15 recipient strains, transconjugants were detected. Based on plating, transfer ratios were between 6.8×10−9 and 3.0×10−2 while using flow cytometry, transfer ratios were between <1.0×10−5 and 1.9×10−2. With a few exceptions, the transconjugants showed phenotypically increased resistance, indicating that most of the transferred resistance genes were expressed. In summary, we showed that an environmental plasmid can be transferred into foodborne pathogenic bacteria at high transfer ratios. However, the transfer ratio seemed to be recipient strain dependent. Moreover, the newly acquired resistance genes could turn antibiotic susceptible strains into resistant ones, paving the way to compromise human health.

  3. Potentiation of Artemisinin Activity against Chloroquine-Resistant Plasmodium falciparum Strains by Using Heme Models

    Science.gov (United States)

    Benoit-Vical, Françoise; Robert, Anne; Meunier, Bernard

    1999-01-01

    The influence of different metalloporphyrin derivatives on the antimalarial activity of artemisinin was studied with two chloroquine-resistant strains of Plasmodium falciparum (FcB1-Colombia and FcM29-Cameroon) cultured in human erythrocytes. This potentiation study indicates that the manganese complex of meso-tetrakis(4-sulfonatophenyl)porphyrin has a significant synergistic effect on the activity of artemisinin against both Plasmodium strains. PMID:10508044

  4. Intra-species Genomic and Physiological Variability Impact Stress Resistance in Strains of Probiotic Potential.

    Science.gov (United States)

    Arnold, Jason W; Simpson, Joshua B; Roach, Jeffrey; Kwintkiewicz, Jakub; Azcarate-Peril, M Andrea

    2018-01-01

    Large-scale microbiome studies have established that most of the diversity contained in the gastrointestinal tract is represented at the strain level; however, exhaustive genomic and physiological characterization of human isolates is still lacking. With increased use of probiotics as interventions for gastrointestinal disorders, genomic and functional characterization of novel microorganisms becomes essential. In this study, we explored the impact of strain-level genomic variability on bacterial physiology of two novel human Lactobacillus rhamnosus strains (AMC143 and AMC010) of probiotic potential in relation to stress resistance. The strains showed differences with known probiotic strains ( L. rhamnosus GG, Lc705, and HN001) at the genomic level, including nucleotide polymorphisms, mutations in non-coding regulatory regions, and rearrangements of genomic architecture. Transcriptomics analysis revealed that gene expression profiles differed between strains when exposed to simulated gastrointestinal stresses, suggesting the presence of unique regulatory systems in each strain. In vitro physiological assays to test resistance to conditions mimicking the gut environment (acid, alkali, and bile stress) showed that growth of L. rhamnosus AMC143 was inhibited upon exposure to alkaline pH, while AMC010 and control strain LGG were unaffected. AMC143 also showed a significant survival advantage compared to the other strains upon bile exposure. Reverse transcription qPCR targeting the bile salt hydrolase gene ( bsh ) revealed that AMC143 expressed bsh poorly (a consequence of a deletion in the bsh promoter and truncation of bsh gene in AMC143), while AMC010 had significantly higher expression levels than AMC143 or LGG. Insertional inactivation of the bsh gene in AMC010 suggested that bsh could be detrimental to bacterial survival during bile stress. Together, these findings show that coupling of classical microbiology with functional genomics methods for the

  5. Intra-species Genomic and Physiological Variability Impact Stress Resistance in Strains of Probiotic Potential

    Directory of Open Access Journals (Sweden)

    Jason W. Arnold

    2018-02-01

    Full Text Available Large-scale microbiome studies have established that most of the diversity contained in the gastrointestinal tract is represented at the strain level; however, exhaustive genomic and physiological characterization of human isolates is still lacking. With increased use of probiotics as interventions for gastrointestinal disorders, genomic and functional characterization of novel microorganisms becomes essential. In this study, we explored the impact of strain-level genomic variability on bacterial physiology of two novel human Lactobacillus rhamnosus strains (AMC143 and AMC010 of probiotic potential in relation to stress resistance. The strains showed differences with known probiotic strains (L. rhamnosus GG, Lc705, and HN001 at the genomic level, including nucleotide polymorphisms, mutations in non-coding regulatory regions, and rearrangements of genomic architecture. Transcriptomics analysis revealed that gene expression profiles differed between strains when exposed to simulated gastrointestinal stresses, suggesting the presence of unique regulatory systems in each strain. In vitro physiological assays to test resistance to conditions mimicking the gut environment (acid, alkali, and bile stress showed that growth of L. rhamnosus AMC143 was inhibited upon exposure to alkaline pH, while AMC010 and control strain LGG were unaffected. AMC143 also showed a significant survival advantage compared to the other strains upon bile exposure. Reverse transcription qPCR targeting the bile salt hydrolase gene (bsh revealed that AMC143 expressed bsh poorly (a consequence of a deletion in the bsh promoter and truncation of bsh gene in AMC143, while AMC010 had significantly higher expression levels than AMC143 or LGG. Insertional inactivation of the bsh gene in AMC010 suggested that bsh could be detrimental to bacterial survival during bile stress. Together, these findings show that coupling of classical microbiology with functional genomics methods for the

  6. Intra-species Genomic and Physiological Variability Impact Stress Resistance in Strains of Probiotic Potential

    Science.gov (United States)

    Arnold, Jason W.; Simpson, Joshua B.; Roach, Jeffrey; Kwintkiewicz, Jakub; Azcarate-Peril, M. Andrea

    2018-01-01

    Large-scale microbiome studies have established that most of the diversity contained in the gastrointestinal tract is represented at the strain level; however, exhaustive genomic and physiological characterization of human isolates is still lacking. With increased use of probiotics as interventions for gastrointestinal disorders, genomic and functional characterization of novel microorganisms becomes essential. In this study, we explored the impact of strain-level genomic variability on bacterial physiology of two novel human Lactobacillus rhamnosus strains (AMC143 and AMC010) of probiotic potential in relation to stress resistance. The strains showed differences with known probiotic strains (L. rhamnosus GG, Lc705, and HN001) at the genomic level, including nucleotide polymorphisms, mutations in non-coding regulatory regions, and rearrangements of genomic architecture. Transcriptomics analysis revealed that gene expression profiles differed between strains when exposed to simulated gastrointestinal stresses, suggesting the presence of unique regulatory systems in each strain. In vitro physiological assays to test resistance to conditions mimicking the gut environment (acid, alkali, and bile stress) showed that growth of L. rhamnosus AMC143 was inhibited upon exposure to alkaline pH, while AMC010 and control strain LGG were unaffected. AMC143 also showed a significant survival advantage compared to the other strains upon bile exposure. Reverse transcription qPCR targeting the bile salt hydrolase gene (bsh) revealed that AMC143 expressed bsh poorly (a consequence of a deletion in the bsh promoter and truncation of bsh gene in AMC143), while AMC010 had significantly higher expression levels than AMC143 or LGG. Insertional inactivation of the bsh gene in AMC010 suggested that bsh could be detrimental to bacterial survival during bile stress. Together, these findings show that coupling of classical microbiology with functional genomics methods for the characterization

  7. Laboratory-based surveillance of current antimicrobial resistance patterns and trends among Staphylococcus aureus: 2005 status in the United States

    Directory of Open Access Journals (Sweden)

    Hogan Patricia

    2006-02-01

    Full Text Available Abstract Background The virulence, antimicrobial resistance, and prevalence of S. aureus underscores the need for up-to-date and extensive insights regarding antimicrobial susceptibility trends. One approach to meet this need is analysis of clinical laboratory – based surveillance data. Methods Data from The Surveillance Network-USA (TSN, an electronic surveillance network that collects microbiology data from 300 clinical microbiology laboratories across the United States, were used as the source for analysis that included prevalence of S. aureus in clinical specimens, MRSA and multi-drug resistance phenotype rates and trends according to patient location, geographic distributions, and specimen source. Results S. aureus was the most prevalent species isolated from inpatient specimens (18.7% of all bacterial isolates and the second most prevalent (14.7% from outpatient specimens. In March 2005 MRSA rates were 59.2%, 55%, and 47.9% for strains from non-ICU inpatients, ICU, and outpatients, respectively. This trend was noted in all nine US Bureau of Census regions and multi-drug resistance phenotypes (resistance to ≥ 3 non-beta-lactams was common among both inpatient MRSA (59.9% and outpatient MRSA (40.8%. Greater than 90% of multi-drug resistant MRSA were susceptible to trimethoprim-sulfamethoxazole, linezolid, and vancomycin. Conclusion Prevalence of MRSA among both inpatient and outpatient specimens continues to increase with multi-drug resistance as a common phenotype. Continued emergence of outpatient MRSA that exhibit multi-drug resistant phenotypes has important implications for developing and evolving outpatient treatment guidelines.

  8. Genetic analysis of resistance to radiation lymphomagenesis with recombinant inbred strains of mice

    International Nuclear Information System (INIS)

    Okumoto, M.; Nishikawa, R.; Imai, S.; Hilgers, J.

    1990-01-01

    Induction of lymphomas by radiation in mice is controlled by genetic factors. We analyzed the genetic control of radiation lymphomagenesis using the CXS series of recombinant inbred strains derived from two progenitor strains: one highly susceptible to radiation induction of lymphoma [BALB/cHeA (C)] and one extremely resistant [STS/A (S)]. The best concordances between strain distribution patterns of genetic markers and resistance (or susceptibility) to radiation lymphomagenesis were observed in a region with the b and Ifa genes on chromosome 4. This indicates that one major locus controls the incidence of radiogenic lymphomas in mice. We designated this locus as the Lyr (lymphoma resistance) locus. Backcrosses of (CXS)F1 to the two progenitor strains showed an intermediate incidence of lymphomas between their parental mice and did not significantly differ from (CXS)F1 mice. This and previous observations that (CXS)F1 mice also showed an intermediate incidence, differing from both progenitor strains, indicate that more genes are involved in the resistance (or susceptibility) to lymphoma induced by irradiation

  9. Esters of pyrazinoic acid are active against pyrazinamide-resistant strains of Mycobacterium tuberculosis and other naturally resistant mycobacteria in vitro and ex vivo within macrophages.

    KAUST Repository

    Pires, David

    2015-10-05

    Pyrazinamide (PZA) is active against major Mycobacterium tuberculosis species (M. tuberculosis, M. africanum, and M. microti), but not against M. bovis and M. avium. The latter two are mycobacteria species involved in human and cattle tuberculosis and in HIV co-infections, respectively. PZA is a first-line agent for the treatment of human tuberculosis and requires activation by a mycobacterial pyrazinamidase to form the active metabolite pyrazinoic acid (POA). As a result of this mechanism, resistance to PZA as often found in tuberculosis patients is caused by point mutations in pyrazinamidase. In previous work, we have shown that POA esters and amides synthesized in our laboratory were stable in plasma. Although the amides did not present significant activity, the esters were active against sensitive mycobacteria at concentrations 5-to-10 fold lower than those of PZA. Here, we report that these POA derivatives possess antibacterial efficacy in vitro and ex vivo against several species and strains of Mycobacterium with natural or acquired resistance to PZA, including M. bovis and M. avium. Our results indicate that the resistance was probably overcome by cleavage of the prodrugs into POA and a long-chain alcohol. Although it is not possible to rule out that the esters may have intrinsic activity per se, we bring evidence here that long-chain fatty alcohols possess a significant anti-mycobacterial effect against PZA-resistant species and strains and are not mere inactive promoieties. These findings may lead to candidate dual-drugs having enhanced activity against both PZA-susceptible and PZA-resistant isolates and being suitable for clinical development.

  10. Isolation of radiation resistant fungal strains from highly radioactive field

    International Nuclear Information System (INIS)

    Adam, Y.M.; Aziz, N.H.; Attaby, H.S.H.

    1995-01-01

    This study examined the radiation resistance of fungal flora isolated from the hot-lab around the radiation sources, cobalt 137 and radium 226 . The predominant mould species were: Aspergillus flavus, A. Niger, penicillium chrysogenum, cladosporium herbarum, fusarium oxysporum and alternaria citri. The D 10 values of F. Oxysporum; 2.00 KGy, A. Flavus; 1.40 KGy, P. chrysogenum; 1.15 KGy, and A. citri; 0.95 KGy, are about 1.67, 3.10, 1.92 and 1.36 folds as the D 1 0 values of the same isolates recovered from soil

  11. Screening of Herbal-Based Bioactive Extract Against Carbapenem-Resistant Strain of Acinetobacter baumannii.

    Science.gov (United States)

    Tiwari, Monalisa; Roy, Ranita; Tiwari, Vishvanath

    2016-07-01

    Acinetobacter baumannii is grouped in the ESKAPE pathogens by Infectious Disease Society of America, which is linked to high degree of morbidity, mortality, and increased costs. The high level of acquired and intrinsic resistance mechanisms of these bacteria makes it an urgent requirement to find a suitable alternative to carbapenem, a commonly prescribed drug for Acinetobacter infection. In this study, methanolic extracts of six medicinal plants were subjected to phytochemical screening and their antimicrobial activity was tested against two strains of A. baumannii (ATCC 19606, carbapenem-sensitive strain, and RS 307, carbapenem-resistant strain). Synergistic effect of the plant extracts and antibiotics was also tested. Bael or Aegle marmelos contains tannin, phenol, terpenoids, glycoside, alkaloids, coumarine, steroid, and quinones. Flowers of madar or Calotropis procera possess tannin, phenol, terpenoids, glycoside, quinone, anthraquinone, anthocyanin, coumarin, and steroid. An inhibitory growth curve was seen for both the bacterial strains when treated with A. marmelos, Curcuma longa, and leaves and flowers of C. procera. Antibiotics alone showed a small zone of inhibition, but when used with herbal extracts they exhibited larger zone of inhibition. Synergistic effect of A. marmelos and imipenem was the best against both the strains of A. baumannii. From this study, it can be concluded that extracts from A. marmelos and leaves and flowers of C. procera exhibited the most effective antibacterial activity. These herbal extracts may be used to screen the bioactive compound against the carbapenem-resistant strain of A. baumannii.

  12. High-Temperature Extensometry and PdCr Temperature-Compensated Wire Resistance Strain Gages Compared

    Science.gov (United States)

    1997-01-01

    A detailed experimental evaluation is underway at the NASA Lewis Research Center to compare and contrast the performance of the PdCr/Pt dual-element temperature-compensated wire resistance strain gage with that of conventional high-temperature extensometry. The advanced PdCr gage, developed by researchers at Lewis, exhibits desirable properties and a relatively small and repeatable apparent strain to 800 C. This gage represents a significant advance in technology because existing commercial resistance strain gages are not reliable for quasi-static strain measurements above approx. 400 C. Various thermal and mechanical loading spectra are being applied by a high-temperature thermomechanical uniaxial testing system to evaluate the two strain-measurement systems. This is being done not only to compare and contrast the two strain sensors, but also to investigate the applicability of the PdCr strain gage to the coupon-level specimen testing environment typically employed when the high-temperature mechanical behavior of structural materials is characterized. Strain measurement capabilities to 800 C are being investigated with a nickel-base superalloy, Inconel 100 (IN 100), substrate material and application to TMC's is being examined with the model system, SCS-6/Ti-15-3. Furthermore, two gage application techniques are being investigated in the comparison study: namely, flame-sprayed and spot welding. The apparent strain responses of both the weldable and flame-sprayed PdCr wire strain gages were found to be cyclically repeatable on both IN 100 and SCS-6/Ti-15-3 [0]_8. In general, each gage exhibited some uniqueness with respect to apparent strain behavior. Gages mounted on the IN 100 specimens tended to show a repeatable apparent strain within the first few cycles, because the thermal response of IN 100 was stable. This was not the case, however, for the TMC specimens, which typically required several thermal cycles to stabilize the thermal strain response. Thus

  13. Field-evolved resistance to Bt maize by western corn rootworm: predictions from the laboratory and effects in the field.

    Science.gov (United States)

    Gassmann, Aaron J

    2012-07-01

    Crops engineered to produce insecticidal toxins derived from the bacterium Bacillus thuringiensis (Bt) provide an effective management tool for many key insect pests. However, pest species have repeatedly demonstrated their ability to adapt to management practices. Results from laboratory selection experiments illustrate the capacity of pest species to evolve Bt resistance. Furthermore, resistance has been documented to Bt sprays in the field and greenhouse, and more recently, by some pests to Bt crops in the field. In 2009, fields were discovered in Iowa (USA) with populations of western corn rootworm, Diabrotica virgifera virgifera LeConte, that had evolved resistance to maize that produces the Bt toxin Cry3Bb1. Fields with resistant insects in 2009 had been planted to Cry3Bb1 maize for at least three consecutive years and as many as 6years. Computer simulation models predicted that the western corn rootworm might evolve resistance to Bt maize in as few as 3years. Laboratory and field data for interactions between western corn rootworm and Bt maize indicate that currently commercialized products are not high-dose events, which increases the risk of resistance evolution because non-recessive resistance traits may enhance survival on Bt maize. Furthermore, genetic analysis of laboratory strains of western corn rootworm has found non-recessive inheritance of resistance. Field studies conducted in two fields identified as harboring Cry3Bb1-resistant western corn rootworm found that survival of western corn rootworm did not differ between Cry3Bb1 maize and non-Bt maize and that root injury to Cry3Bb1 maize was higher than injury to other types of Bt maize or to maize roots protected with a soil insecticide. These first cases of field-evolved resistance to Bt maize by western corn rootworm provide an early warning and point to the need to apply better integrated pest management practices when using Bt maize to manage western corn rootworm. Copyright © 2012 Elsevier

  14. Identification of Resistance to Wet Bubble Disease and Genetic Diversity in Wild and Cultivated Strains of Agaricus bisporus

    Directory of Open Access Journals (Sweden)

    Yongping Fu

    2016-09-01

    Full Text Available Outbreaks of wet bubble disease (WBD caused by Mycogone perniciosa are increasing across the world and seriously affecting the yield of Agaricus bisporus. However, highly WBD-resistant strains are rare. Here, we tested 28 A. bisporus strains for WBD resistance by inoculating M. perniciosa spore suspension on casing soil, and assessed genetic diversity of these strains using 17 new simple sequence repeat (SSR markers developed in this study. We found that 10 wild strains originating from the Tibetan Plateau in China were highly WBD-resistant strains, and 13 cultivated strains from six countries were highly susceptible strains. A total of 88 alleles were detected in these 28 strains, and the observed number of alleles per locus ranged from 2 to 8. Cluster and genetic structure analysis results revealed the wild resources from China have a relatively high level of genetic diversity and occur at low level of gene flow and introgression with cultivated strains. Moreover, the wild strains from China potentially have the consensus ancestral genotypes different from the cultivated strains and evolved independently. Therefore, the highly WBD-resistant wild strains from China and newly developed SSR markers could be used as novel sources for WBD-resistant breeding and quantitative trait locus (QTL mapping of WBD-resistant gene of A. bisporus.

  15. [Genetic determinants of resistance of hospital-associated strains of Klebsiella pneumoniae to β-lactam antibiotics isolated in neonates].

    Science.gov (United States)

    Dubodelov, D V; Lubasovskaya, L A; Shubina, E S; Mukosey, I S; Korostin, D O; Kochetkova, T O; Bogacheva, N A; Bistritskiy, A A; Gordeev, A B; Trofimov, D Y; Priputnevich, T V; Zubkov, V V

    2016-09-01

    According to the results of analysis of whole genome sequencing, the presence of genes having resistance to β-lactam antibiotics in hospital-associated strains of Klebsiella pneumoniae was studied. The strains were isolated from neonatal intensive care units. The data obtained were compared with the results of antimicrobial susceptibility testing of isolated microorganisms. Among other strains resistant to cephalosporins, the dominance of genes of CTX-M-type extended-spectrum β-lactamases was shown. It was revealed that one of eight strains phenotypically resistant and moderately resistant to carbapenems have the blaOXA-48 carbapenemase gene.

  16. Colistin Resistance in Escherichia coli and Salmonella enterica Strains Isolated from Swine in Brazil

    Directory of Open Access Journals (Sweden)

    Adriano Savoia Morales

    2012-01-01

    Full Text Available Reports about acquired resistance to colistin in different bacteria species are increasing, including E. coli of animal origin, but reports of resistance in wild S. enterica of different serotypes from swine are not found in the literature. Results obtained with one hundred and twenty-six E. coli strains from diseased swine and one hundred and twenty-four S. enterica strains from diseased and carrier swine showed a frequency of 6.3% and 21% of colistin-resistant strains, respectively. When comparing the disk diffusion test with the agar dilution test to evaluate the strains, it was confirmed that the disk diffusion test is not recommended to evaluate colistin resistance as described previously. The colistin MIC 90 and MIC 50 values obtained to E. coli were 0.25 μg/mL and 0.5 μg/mL, the MIC 90 and MIC 50 to S. enterica were 1 μg/mL and 8 μg/mL. Considering the importance of colistin in control of nosocomial human infections with Gram-negative multiresistant bacteria, and the large use of this drug in animal production, the colistin resistance prevalence in enterobacteriaceae of animal origin must be monitored more closely.

  17. Colistin resistance in Escherichia coli and Salmonella enterica strains isolated from swine in Brazil.

    Science.gov (United States)

    Morales, Adriano Savoia; Fragoso de Araújo, Juliana; de Moura Gomes, Vasco Túlio; Reis Costa, Adrienny Trindade; dos Prazeres Rodrigues, Dália; Porfida Ferreira, Thais Sebastiana; de Lima Filsner, Pedro Henrique Nogueira; Felizardo, Maria Roberta; Micke Moreno, Andrea

    2012-01-01

    Reports about acquired resistance to colistin in different bacteria species are increasing, including E. coli of animal origin, but reports of resistance in wild S. enterica of different serotypes from swine are not found in the literature. Results obtained with one hundred and twenty-six E. coli strains from diseased swine and one hundred and twenty-four S. enterica strains from diseased and carrier swine showed a frequency of 6.3% and 21% of colistin-resistant strains, respectively. When comparing the disk diffusion test with the agar dilution test to evaluate the strains, it was confirmed that the disk diffusion test is not recommended to evaluate colistin resistance as described previously. The colistin MIC 90 and MIC 50 values obtained to E. coli were 0.25 μg/mL and 0.5 μg/mL, the MIC 90 and MIC 50 to S. enterica were 1 μg/mL and 8 μg/mL. Considering the importance of colistin in control of nosocomial human infections with Gram-negative multiresistant bacteria, and the large use of this drug in animal production, the colistin resistance prevalence in enterobacteriaceae of animal origin must be monitored more closely.

  18. Rapid change in the ciprofloxacin resistance pattern among Neisseria gonorrhoeae strains in Nuuk, Greenland

    DEFF Research Database (Denmark)

    Skjerbæk Rolskov, Anne; Bjorn-Mortensen, Karen; Mulvad, Gert

    2015-01-01

    ProbeTec). Monitoring of GC antibiotic susceptibility by culture was introduced in Nuuk in 2012. Until 2014, no cases of ciprofloxacin-resistant GC strains were reported. In this paper, we report the finding of ciprofloxacin-resistant GC and describe the most recent incidence of GC infections...... (9%) were positive, respectively. From January to August, 6 (15%) cultures from Nuuk were ciprofloxacin resistant while in September and October, 26 (59%) were ciprofloxacin resistant (presistance. GC incidence in Nuuk...... was 3,017 per 100,000 inhabitants per year, compared to 2,491 per 100,000 inhabitants per year in the rest of Greenland. CONCLUSION: Within a short period, a rapid and dramatic change in ciprofloxacin susceptibility among GC strains isolated in Nuuk was documented and recommendation for first line...

  19. Enhanced resistance to fluoroquinolones in laboratory-grown mutants & clinical isolates of Shigella due to synergism between efflux pump expression & mutations in quinolone resistance determining region.

    Science.gov (United States)

    Taneja, Neelam; Mishra, Arti; Kumar, Ajay; Verma, Garima; Sharma, Meera

    2015-01-01

    There is a worldwide emergence of fluoroquinolone resistance in Shigella species. To understand the molecular mechanisms associated with fluoroquinolone resistance, naturally occurring fluoroquinolone-resistant strains and laboratory-induced spontaneous mutants of Shigella spp. were used and the relative contributions of acrAB-tolC efflux pumps, gyrase and topoisomerase target gene mutations towards fluoroquinolone resistance were determined. Eight Shigella flexneri and six S. dysenteriae clinical isolates were studied. Three consecutive mutants resistant to ciprofloxacin for S. flexneri SFM1 (≥ 0.25 µg/ml), SFM2 (≥ 4 µg/ml) and SFM3 (≥ 32 µg/ml) were selected in 15 steps from susceptible isolates by serial exposure to increasing concentrations of nalidixic acid and ciprofloxacin. Similarly, two mutants for S. dysenteriae SDM1 (≥ 0.25 µg/ml) and SDM2 (≥ 4 µg/ml) were selected in eight steps. After PCR amplification sequence analyses of gyrase and topoisomerase target genes were performed. Expression of efflux genes acrA, acrB, acrR and tolC was measured using real-time PCR. Mutations were observed in gyrA Ser [83]→Leu, Asp [87]→Asn/Gly, Val [196]→Ala and in parC Phe [93]→Val, Ser [80]→Ile, Asp [101]→Glu and Asp [110]→Glu. Overall, acrA and acrB overexpression was associated with fluoroquinolone resistance ( p0 Shigella spp. is the end product of either a single or a combination of mutations in QRDRs and/ or efflux activity. Novel polymorphisms were observed at Val [196]→Ala in gyrA in clinical isolates and Phe [93]→Val, Asp [101]→Glu, Asp [110]→Glu and in parC in majority of laboratory-grown mutants.

  20. [Investigation of OXA type beta-lactamases and PFGE patterns in Acinetobacter baumannii strains resistant to carbapenems].

    Science.gov (United States)

    Keyik, Serafettin; Arslan, Uğur; Türk Dağı, Hatice; Seyhan, Tuba; Fındık, Duygu

    2014-10-01

    Acinetobacter baumannii is an important opportunistic and multidrug-resistant pathogen leading to nosocomial infections. Over the last 10 years, a significant and threatening increase in resistance to carbapenems, mainly due to the dissemination of class D beta-lactamases, has been reported in A.baumannii worldwide. The most common types of beta-lactamases causing carbapenem resistance in A.baumannii are the OXA-23, OXA-24, OXA-40, OXA-58 and OXA-143 type serine beta-lactamases. The aim of this study was to investigate the presence of OXA type beta-lactamases in carbapenem-resistant A.baumannii strains and the clonal relationship between the strains. A total of 105 non-duplicate carbapenem-resistant A.baumannii strains isolated from various clinical samples (68 blood, 18 bronchoalveolar lavage, 13 drainage, 3 urine, 2 cerebrospinal fluid and 1 catheter samples) in the Microbiology Laboratories of Selcuk University, Meram (2009-2012) and Selcuklu (2007-2008) Medical School Hospitals, were included in the study. The isolates were identified by conventional methods and Phoenix 100 BD (BD Diagnostic, USA) and Vitek II (bioMerieux, France) automated systems. Carbapenem susceptibility test was performed by Kirby-Bauer disk diffusion method according to the CLSI standards. bla(OXA 23-like), bla(OXA 24-like), bla(OXA 58-like) and bla(OXA 51-like) genes were amplified by multiplex PCR assay and clonal relatedness was investigated by pulsed-field gel electrophoresis (PFGE) using ApaI enzyme. The bla(OXA 51-like) gene was determined in all carbapenem-resistant A.baumannii isolates, while the bla(OXA 23-like) and bla(OXA 58-like) genes were detected in 46.6% and 53.3% of isolates, respectively. However bla(OXA 24-like) gene was not demonstrated in any isolates. bla(OXA 23-like) gene was determined in both Meram and Selcuklu Medical School hospitals, but bla(OXA 58-like) gene was detected only in Meram Medical School hospital. PFGE analysis of the isolates revealed 32 different

  1. Rapid emergence of a ceftazidime-resistant Burkholderia multivorans strain in a cystic fibrosis patient.

    Science.gov (United States)

    Stokell, Joshua R; Gharaibeh, Raad Z; Steck, Todd R

    2013-12-01

    Burkholderia multivorans poses a serious health threat to cystic fibrosis patients due to innate resistance to multiple antibiotics and acquisition of resistance to a range of antibiotics due to the frequent use of antibiotics to treat chronic infections. Monitoring antibiotic susceptibility is crucial to managing patient care. We identified the rapid emergence of a ceftazidime-resistant strain in a single patient within four days during a hospitalization for treatment of an exacerbation. B. multivorans was isolated from expectorated sputum samples using Burkholderia cepacia selective agar. A macrodilution assay was performed on all isolates to determine the minimum inhibitory concentration of ceftazidime. Approximately 4000 colonies were scored to identify the percent of ceftazidime-resistant colonies. Extracted DNA was used to determine the total bacterial counts and abundance of B. multivorans using quantitative PCR. An increase from no detectable B. multivorans ceftazidime-resistant colonies to over 75% of all colonies tested occurred within a four-day period. The resistant population remained dominant in 6 of the 8 samples in the following 17 months of the study. qPCR revealed an association between change in the percent of resistant colonies and abundance of B. multivorans, but not of total bacteria. No association was found between the acquisition of resistance to ceftazidime and other antibiotics commonly used to treat B. multivorans infections. The rapid emergence of a ceftazidime-resistant by B. multivorans strain occurred during a hospitalization while under selective pressure of antibiotics. The resistant strain maintained dominance in the B. multivorans population which resulted in an overall decline in a patient health and treatment efficacy. Copyright © 2013 European Cystic Fibrosis Society. Published by Elsevier B.V. All rights reserved.

  2. Linezolid-resistant Staphylococcus aureus strain 1128105, the first known clinical isolate possessing the cfr multidrug resistance gene.

    Science.gov (United States)

    Locke, Jeffrey B; Zuill, Douglas E; Scharn, Caitlyn R; Deane, Jennifer; Sahm, Daniel F; Denys, Gerald A; Goering, Richard V; Shaw, Karen J

    2014-11-01

    The Cfr methyltransferase confers resistance to six classes of drugs which target the peptidyl transferase center of the 50S ribosomal subunit, including some oxazolidinones, such as linezolid (LZD). The mobile cfr gene was identified in European veterinary isolates from the late 1990s, although the earliest report of a clinical cfr-positive strain was the 2005 Colombian methicillin-resistant Staphylococcus aureus (MRSA) isolate CM05. Here, through retrospective analysis of LZD(r) clinical strains from a U.S. surveillance program, we identified a cfr-positive MRSA isolate, 1128105, from January 2005, predating CM05 by 5 months. Molecular typing of 1128105 revealed a unique pulsed-field gel electrophoresis (PFGE) profile most similar to that of USA100, spa type t002, and multilocus sequence type 5 (ST5). In addition to cfr, LZD resistance in 1128105 is partially attributed to the presence of a single copy of the 23S rRNA gene mutation T2500A. Transformation of the ∼37-kb conjugative p1128105 cfr-bearing plasmid from 1128105 into S. aureus ATCC 29213 background strains was successful in recapitulating the Cfr antibiogram, as well as resistance to aminoglycosides and trimethoprim. A 7-kb cfr-containing region of p1128105 possessed sequence nearly identical to that found in the Chinese veterinary Proteus vulgaris isolate PV-01 and in U.S. clinical S. aureus isolate 1900, although the presence of IS431-like sequences is unique to p1128105. The cfr gene environment in this early clinical cfr-positive isolate has now been identified in Gram-positive and Gram-negative strains of clinical and veterinary origin and has been associated with multiple mobile elements, highlighting the versatility of this multidrug resistance gene and its potential for further dissemination. Copyright © 2014, American Society for Microbiology. All Rights Reserved.

  3. Studies of the strain-dependent properties of A15 filamentary conductors at Brookhaven National Laboratory

    International Nuclear Information System (INIS)

    Luhman, T.; Welch, D.O.

    1980-01-01

    Work at BNL pertaining to the strain response of filamentary bronze-processed superconductors is reviewed. This work includes the intrinsic strain dependence of the critical properties of A15 structure compounds, the nature of the initial internal strain state of composite conductors, and the interplay between these residual strains and applied strains which governs the response of the conductor to external strain. Some factors which can enhance the strain tolerances of filamentary conductors are briefly discussed

  4. Survey on the phage resistance mechanisms displayed by a dairy Lactobacillus helveticus strain.

    Science.gov (United States)

    Zago, Miriam; Orrù, Luigi; Rossetti, Lia; Lamontanara, Antonella; Fornasari, Maria Emanuela; Bonvini, Barbara; Meucci, Aurora; Carminati, Domenico; Cattivelli, Luigi; Giraffa, Giorgio

    2017-09-01

    In this study the presence and functionality of phage defence mechanisms in Lactobacillus helveticus ATCC 10386, a strain of dairy origin which is sensitive to ΦLh56, were investigated. After exposure of ATCC 10386 to ΦLh56, the whole-genome sequences of ATCC 10386 and of a phage-resistant derivative (LhM3) were compared. LhM3 showed deletions in the S-layer protein and a higher expression of the genes involved in the restriction/modification (R/M) system. Genetic data were substantiated by measurements of bacteriophage adsorption rates, efficiency of plaquing, cell wall protein size and by gene expression analysis. In LhM3 two phage resistance mechanisms, the inhibition of phage adsorption and the upregulation of Type I R/M genes, take place and explain its resistance to ΦLh56. Although present in both ATCC 10386 and LhM3 genomes, the CRISPR machinery did not seem to play a role in the phage resistance of LhM3. Overall, the natural selection of phage resistant strains resulted successful in detecting variants carrying multiple phage defence mechanisms in L. helveticus. The concurrent presence of multiple phage-resistance systems should provide starter strains with increased fitness and robustness in dairy ecosystems. Copyright © 2017 Elsevier Ltd. All rights reserved.

  5. DNA gyrase and topoisomerase IV mutations in an in vitro fluoroquinolone-resistant Coxiella burnetii strain.

    Science.gov (United States)

    Vranakis, Iosif; Sandalakis, Vassilios; Chochlakis, Dimosthenis; Tselentis, Yannis; Psaroulaki, Anna

    2010-06-01

    The etiological agent of Q fever, Coxiella burnetii, is an obligate intracellular bacterium that multiplies within a vacuole with lysosomal characteristics. Quinolones have been used as an alternative therapy for Q fever. In this study, quinolone-resistance-determining regions of the genes coding for DNA gyrase and topoisomerase IV were analyzed by DNA sequencing from an in vitro fluoroquinolone-resistant C. burnetii strain (Q212). Sequencing and aligning of DNA gyrase encoding genes (gyrA and gyrB) and topoisomerase IV genes (parC and parE) revealed one gyrA mutation leading to the amino acid substitution Asp87Gly (Escherichia coli numbering), two gyrB mutations leading to the amino acid substitutions Ser431Pro and Met518Ile, and three parC mutations leading to the amino acid substitutions Asp69Asn, Thr80Ile, and Gly104Ser. The corresponding alignment of the C. burnetii Q212 reference strain, the in vitro developed fluoroquinolone-resistant C. burnetii Q212 strain, and E. coli resulted in the identification of several other naturally occurring mutations within and outside the quinolone-resistance-determining regions of C. burnetii providing indications of possible natural resistance to fluoroquinolones. The present study adds additional potential mutations in the DNA topoisomerases that may be involved in fluoroquinolone resistance in C. burnetii due to their previous characterization in other bacterial species.

  6. Thiamethoxam acts as a target-site synergist of spinosad in resistant strains of Frankliniella occidentalis.

    Science.gov (United States)

    Guillén, Juan; Bielza, Pablo

    2013-02-01

    Previous studies have suggested that the resistance mechanism towards spinosad in Frankliniella occidentalis (Pergande) is an altered target site. Like the neonicotinoids, the spinosyns act on nicotinic acetylcholine receptors (nAChRs) in insects, but at a distinct site. The changes in nAChRs related to spinosad resistance in thrips might involve interaction with neonicotinoids. In this study, the efficacy of spinosad and neonicotinoids, alone and in combination, was evaluated in susceptible and spinosad-resistant thrips strains. The neonicotinoids tested were imidacloprid, thiacloprid, acetamiprid, thiamethoxam and clothianidin. No cross-resistance was shown between spinosad and any of the neonicotinoids. However, an increased toxicity was observed when a mixture of spinosad with thiamethoxam or clothianidin was tested. No synergism was found in the susceptible strains. The more spinosad-resistant the thrips strain, the stronger was the synergism. Data suggest that spinosad and thiamethoxam may interact at the nAChRs in spinosad-resistant thrips, facilitating enhanced insecticidal action. Copyright © 2012 Society of Chemical Industry.

  7. World Health Organization/HIVResNet drug resistance laboratory strategy

    NARCIS (Netherlands)

    Bertognolio, Silvio; Derdelinckx, Inge; Parker, Monica; Fitzgibbon, Joseph; Fleury, Herve; Peeters, Martin; Schuurman, Rob; Pillay, Deenan; Morris, Lynn; Tanuri, Amilcar; Gershy-Damet, Guy-Michel; Nkengasong, John; Gilks, Charles F.; Sutherland, Donald; Sandstrom, Paul

    2008-01-01

    With rapidly increasing access to antiretroviral drugs globally, HIV drug resistance (HIVDR) has become a significant public health issue, This requires a coordinated and collaborative response from country level to international level to assess the extent of HIVDR and the establishment of efficient

  8. Comparisons of Transcriptional Profiles of Gut Genes between Cry1Ab-Resistant and Susceptible Strains of Ostrinia nubilalis Revealed Genes Possibly Related to the Adaptation of Resistant Larvae to Transgenic Cry1Ab Corn

    Directory of Open Access Journals (Sweden)

    Jianxiu Yao

    2017-01-01

    Full Text Available A microarray developed on the basis of 2895 unique transcripts from larval gut was used to compare gut gene expression profiles between a laboratory-selected Cry1Ab-resistant (R strain and its isoline susceptible (S strain of the European corn borer (Ostrinia nubilalis after the larvae were fed the leaves of transgenic corn (MON810 expressing Cry1Ab or its non-transgenic isoline for 6 h. We revealed 398 gut genes differentially expressed (i.e., either up- or down-regulated genes with expression ratio ≥2.0 in S-strain, but only 264 gut genes differentially expressed in R-strain after being fed transgenic corn leaves. Although the percentages of down-regulated genes among the total number of differentially expressed genes (50% in S-strain and 45% in R-strain were similar between the R- and S-strains, the expression ratios of down-regulated genes were much higher in S-strain than in R-strain. We revealed that 17 and 9 significantly up- or down-regulated gut genes from S and R-strain, respectively, including serine proteases and aminopeptidases. These genes may be associated with Cry1Ab toxicity by degradation, binding, and cellular defense. Overall, our study suggests enhanced adaptation of Cry1Ab-resistant larvae on transgenic Cry1Ab corn as revealed by lower number and lower ratios of differentially expressed genes in R-strain than in S-strain of O. nubilalis.

  9. Diversity of Antibiotic Resistance Genes in Enterococcus Strains Isolated from Ready-to-Eat Meat Products.

    Science.gov (United States)

    Chajęcka-Wierzchowska, Wioleta; Zadernowska, Anna; Łaniewska-Trokenheim, Łucja

    2016-10-25

    The objective of the study was to answer the question of whether the ready-to-eat meat products can pose indirect hazard for consumer health serving as reservoir of Enterococcus strains harboring tetracyclines, aminoglycosides, and macrolides resistance genes. A total of 390 samples of ready-to-eat meat products were investigated. Enterococcus strains were found in 74.1% of the samples. A total of 302 strains were classified as: Enterococcus faecalis (48.7%), Enterococcus faecium (39.7%), Enterococcus casseliflavus (4.3%), Enterococcus durans (3.0%), Enterococcus hirae (2.6%), and other Enterococcus spp. (1.7%). A high percentage of isolates were resistant to streptomycin high level (45%) followed by erythromycin (42.7%), fosfomycin (27.2%), rifampicin (19.2%), tetracycline (36.4%), tigecycline (19.9%). The ant(6')-Ia gene was the most frequently found gene (79.6%). Among the other genes that encode aminoglycosides-modifying enzymes, the highest portion of the strains had the aac(6')-Ie-aph(2'')-Ia (18.5%) and aph(3'')-IIIa (16.6%), but resistance of isolates from food is also an effect of the presence of aph(2'')-Ib, aph(2'')-Ic, aph(2'')-Id genes. Resistance to tetracyclines was associated with the presence of tetM (43.7%), tetL (32.1%), tetK (14.6%), tetW (0.7%), and tetO (0.3%) genes. The ermB and ermA genes were found in 33.8% and 18.9% of isolates, respectively. Nearly half of the isolates contained a conjugative transposon of the Tn916/Tn1545 family. Enterococci are widely present in retail ready-to-eat meat products. Many isolated strains (including such species as E. casseliflavus, E. durans, E. hirae, and Enterococcus gallinarum) are antibiotic resistant and carry transferable resistance genes. © 2016 Institute of Food Technologists®.

  10. Comparative usage of herpesvirus entry mediator A and nectin-1 by laboratory strains and clinical isolates of herpes simplex virus

    International Nuclear Information System (INIS)

    Krummenacher, Claude; Baribaud, Frederic; Ponce de Leon, Manuel; Baribaud, Isabelle; Whitbeck, J. Charles; Xu Ruliang; Cohen, Gary H.; Eisenberg, Roselyn J.

    2004-01-01

    The herpesvirus entry mediator A (HVEM/HveA) and nectin-1 (HveC/CD111) are two major receptors for herpes simplex virus (HSV). Although structurally unrelated, both receptors can independently mediate entry of wild-type (wt) HSV-1 and HSV-2 by interacting with the viral envelope glycoprotein D (gD). Laboratory strains with defined mutations in gD (e.g. rid1) do not use HVEM but use nectin-2 (HveB/CD112) for entry. The relative usage of HVEM and nectin-1 during HSV infection in vivo is not known. In the absence of a defined in vivo model, we used in vitro approaches to address this question. First, we screened HSV clinical isolates from various origins for receptor tropism and found that all used both HVEM and nectin-1. Second, we determined the numbers of surface receptors on various susceptible and resistant cell lines as well as on primary fibroblasts derived from an individual with cleft lip/palate ectodermal dysplasia (CLPED1). Although CLPED1 cells can only express a defective form of nectin-1, they allowed entry of wild type and mutant HSV strains by usage of either HVEM or nectin-2. Finally, we compared the ability of HVEM and nectin-1 to mediate entry when expressed at varying cell surface densities. Both receptors showed a direct relationship between the number of receptors and HSV susceptibility. Direct comparison of receptors suggests that nectin-1 is more efficient at promoting entry than HVEM. Overall, our data suggest that both receptors play a role during HSV infection in vivo and that both are highly efficient even at low levels of expression

  11. Comparison of the protective resistance induced by 60Co-irradiated cercariae and schistosomula of the WFFS and NMRI strains of Schistosoma mansoni

    International Nuclear Information System (INIS)

    James, E.R.; Dobinson, A.R.

    1985-01-01

    Mice, CBA/HT6T6 and C57BL/10, were vaccinated with 1 x 350 or 1 x 500 Schistosoma mansoni cercariae or schistosomula attenuated with 20 or 56 krad 60 Co irradiation and challenged with 200 cercariae. Protective resistance against homologous strain challenge was compared using the Winches Farm Field Station (WFFS) and Naval Medical Research Institute (NMRI) strains of S. mansoni. Maximal resistance to challenge was obtained in both strains of mice with cercariae or schistosomula of either WFFS or NMRI strain attenuated with 20 krad. Protection using organisms attenuated with 56 krad was significantly lower. Since previous studies with the two parasite strains have shown that the biological effects of irradiation are similar, the difference in the immunogenicity of the 56 krad-irradiated NMRI strain in this study from earlier studies must be due either to different local conditions for irradiation or to adaptation of the NMRI strain to a new laboratory environment. This finding may have important implications for vaccination studies and investigations of the mechanisms of immunity where radiation-attenuated parasites are used. (author)

  12. Characterization of in vivo-acquired resistance to macrolides of Mycoplasma gallisepticum strains isolated from poultry

    Directory of Open Access Journals (Sweden)

    Gerchman Irena

    2011-08-01

    Full Text Available Abstract The macrolide class of antibiotics, including tylosin and tilmicosin, is widely used in the veterinary field for prophylaxis and treatment of mycoplasmosis. In vitro susceptibility testing of 50 strains of M. gallisepticum isolated in Israel during the period 1997-2010 revealed that acquired resistance to tylosin as well as to tilmicosin was present in 50% of them. Moreover, 72% (13/18 of the strains isolated from clinical samples since 2006 showed acquired resistance to enrofloxacin, tylosin and tilmicosin. Molecular typing of the field isolates, performed by gene-target sequencing (GTS, detected 13 molecular types (I-XIII. Type II was the predominant type prior to 2006 whereas type X, first detected in 2008, is currently prevalent. All ten type X strains were resistant to both fluoroquinolones and macrolides, suggesting selective pressure leading to clonal dissemination of resistance. However, this was not a unique event since resistant strains with other GTS molecular types were also found. Concurrently, the molecular basis for macrolide resistance in M. gallisepticum was identified. Our results revealed a clear-cut correlation between single point mutations A2058G or A2059G in domain V of the gene encoding 23S rRNA (rrnA, MGA_01 and acquired macrolide resistance in M. gallisepticum. Indeed, all isolates with MIC ≥ 0.63 μg/mL to tylosin and with MIC ≥ 1.25 μg/mL to tilmicosin possess one of these mutations, suggesting an essential role in decreased susceptibility of M. gallisepticum to 16-membered macrolides.

  13. Glutathione metabolism in Candida albicans resistant strains to fluconazole and micafungin.

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    Bruno Maras

    Full Text Available Currently available therapies for candidiasis are based on antifungal drugs belonging to azole and echinocandin families that interfere with different aspects of fungal metabolism. These drugs, beyond their specific effects, elicit also a cellular stress including an unbalance of redox state that is counteracted not only utilizing antioxidant species but also increasing the outcome export by transporters to detoxify the internal environment. These cellular actions are both based on the cytosolic concentration of reduced glutathione (GSH. In this paper we investigated the effects of two antifungal drugs fluconazole and micafungin on the redox state of the cell in C. albicans to understand if the resistance to these drugs is accompanied by variation of glutathione metabolism. Analyses of resistant strains showed a marked difference in glutathione contents in strains resistant to fluconazole (CO23RFLC or micafungin (CO23RFK. In CO23RFLC, the total amount of glutathione was more than doubled with respect to CO23RFK thanks to the increased activity of γ-glutamilcysteine synthetase, the key enzyme involved in GSH synthesis. We demonstrated that the GSH increase in CO23RFLC conferred to this strain a clear advantage in counteracting oxidative toxic agents while assignment of other roles, such as a more efficient elimination of the drug from the cell, should be considered more speculative. As far as MCFG resistance is concerned, from our data a role of glutathione metabolism in supporting this condition is not evident. Overall our data indicate that glutathione metabolism is differently affected in the two resistant strains and that glutathione system may play an important role in the global organization of C.albicans cells for resistance to fluconazole. Such scenario may pave the way to hypothesize the use of oxidant drugs or inhibitors able to deplete reduced glutathione level as a novel approach, for counteracting the resistance to this specific

  14. Controlling antimicrobial resistance through targeted, vaccine-induced replacement of strains.

    Directory of Open Access Journals (Sweden)

    Yonas I Tekle

    Full Text Available Vaccination has proven effective in controlling many infectious diseases. However, differential effectiveness with regard to pathogen genotype is a frequent reason for failures in vaccine development. Often, insufficient immune response is induced to prevent infection by the diversity of existing serotypes present in pathogenic populations of bacteria. These vaccines that target a too narrow spectrum of serotypes do not offer sufficient prevention of infections, and can also lead to undesirable strain replacements. Here, we examine a novel idea to specifically exploit the narrow spectrum coverage of some vaccines to combat specific, emerging multi- and pan-resistant strains of pathogens. Application of a narrow-spectrum vaccine could serve to prevent infections by some strains that are hard to treat, rather than offer the vaccinated individual protection against infections by the pathogenic species as such. We suggest that vaccines targeted to resistant serotypes have the potential to become important public health tools, and would represent a new approach toward reducing the burden of particular multi-resistant strains occurring in hospitals. Vaccines targeting drug-resistant serotypes would also be the first clinical intervention with the potential to drive the evolution of pathogenic populations toward drug-sensitivity. We illustrate the feasibility of this approach by modeling a hypothetical vaccine that targets a subset of methicillin-resistant Staphylococcus aureus (MRSA genotypes, in combination with drug treatment targeted at drug-sensitive genotypes. We find that a combined intervention strategy can limit nosocomial outbreaks, even when vaccine efficacy is imperfect. The broader utility of vaccine-based resistance control strategies should be further explored taking into account population structure, and the resistance and transmission patterns of the pathogen considered.

  15. Activity of the thiopeptide antibiotic nosiheptide against contemporary strains of methicillin-resistant Staphylococcus aureus.

    Science.gov (United States)

    Haste, Nina M; Thienphrapa, Wdee; Tran, Dan N; Loesgen, Sandra; Sun, Peng; Nam, Sang-Jip; Jensen, Paul R; Fenical, William; Sakoulas, George; Nizet, Victor; Hensler, Mary E

    2012-12-01

    The rapid rise in antimicrobial resistance in bacteria has generated an increased demand for the development of novel therapies to treat contemporary infections, especially those caused by methicillin-resistant Staphylococcus aureus (MRSA). However, antimicrobial development has been largely abandoned by the pharmaceutical industry. We recently isolated the previously described thiopeptide antibiotic nosiheptide from a marine actinomycete strain and evaluated its activity against contemporary clinically relevant bacterial pathogens. Nosiheptide exhibited extremely potent activity against all contemporary MRSA strains tested including multiple drug-resistant clinical isolates, with MIC values 0.25 mg l(-1). Nosiheptide was also highly active against Enterococcus spp. and the contemporary hypervirulent BI/NAP1/027 strain of Clostridium difficile but was inactive against most Gram-negative strains tested. Time-kill analysis revealed nosiheptide to be rapidly bactericidal against MRSA in a concentration- and time-dependent manner, with a nearly 2-log kill noted at 6 h at 10 × MIC. Furthermore, nosiheptide was found to be non-cytotoxic against mammalian cells at >100 × MIC, and its anti-MRSA activity was not inhibited by 20% human serum. Notably, nosiheptide exhibited a significantly prolonged post-antibiotic effect against both healthcare- and community-associated MRSA compared with vancomycin. Nosiheptide also demonstrated in vivo activity in a murine model of MRSA infection, and therefore represents a promising antibiotic for the treatment of serious infections caused by contemporary strains of MRSA.

  16. Genotyping of Methicillin Resistant Staphylococcus aureus Strains Isolated from Hospitalized Children

    Directory of Open Access Journals (Sweden)

    Mouna Ben Nejma

    2014-01-01

    Full Text Available Community associated methicillin resistant Staphylococcus aureus (CA-MRSA is an emerging pathogen increasingly reported to cause skin and soft tissue infections for children. The emergence of highly virulencet CA-MRSA strains in the immunodeficiency of young children seemed to be the basic explanation of the increased incidence of CA-MRSA infections among this population. The subjects of this study were 8 patients hospitalized in the Pediatric Department at the University Hospital of Monastir. The patients were young children (aged from 12 days to 18 months who were suffering from MRSA skin infections; two of them had the infections within 72 h of their admission. The isolates were classified as community isolates as they all carried the staphylococcal cassette chromosome mec (SCCmec IV and pvl genes. Epidemiological techniques, pulsed-field gel electrophoresis (PFGE and multilocus sequence typing (MLST, were applied to investigate CA-MRSA strains. Analysis of molecular data revealed that MRSA strains were related according to PFGE patterns and they belonged to a single clone ST80. Antimicrobial susceptibility tests showed that all strains were resistant to kanamycin and 2 strains were resistant to erythromycin.

  17. Laboratory evaluation of resistance to moisture damage in asphalt mixtures

    Directory of Open Access Journals (Sweden)

    Ahmed Ebrahim Abu El-Maaty Behiry

    2013-09-01

    Full Text Available Moisture damage in asphalt mixtures refers to loss in strength and durability due to the presence of water. Egypt road network is showing severe deterioration such as raveling and stripping because the bond between aggregates and asphalt film is broken due to water intrusion. To minimize moisture damage, asphalt mixes are investigated to evaluate the effect of air voids, degree of saturation, media of attack and the conditioning period. Two medias of attack are considered and two anti-stripping additives are used (hydrated lime and Portland cement. The retained Marshall stability and tensile strength ratio are calculated to determine the resistance to moisture damage. The results showed that both lime and cement could increase Marshall stability, resilient modulus, tensile strength and resistance to moisture damage of mixtures especially at higher condition periods. Use of hydrated lime had better results than Portland cement.

  18. Antimicrobial susceptibilities and resistance genes in Campylobacter strains isolated from poultry and pigs in Australia.

    Science.gov (United States)

    Obeng, A S; Rickard, H; Sexton, M; Pang, Y; Peng, H; Barton, M

    2012-08-01

    To evaluate the phenotypic and genotypic profiles of Campylobacter spp. from poultry faecal samples from free range or intensively raised meat chickens and free range egg layers. In addition, a case-comparison study of antibiotic resistance genes from different groups of poultry and some pig strains previously collected was carried out. Resistance to different antibiotics was assessed using the agar dilution method. In addition, all the strains were tested for ampicillin (bla(OXA-61) ), erythromycin (aph-3-1), tetracycline tet(O), streptomycin (aadE), and the energy-dependent multi-drug efflux pump (cmeB) resistance genes using multiplex polymerase chain reaction. The evaluation of phenotypic resistance revealed all of the strains from poultry were sensitive to ciprofloxacin, gentamicin, erythromycin or tylosin. But, widespread resistance to lincomycin (51-100%), extensive resistance to ampicillin (33·3-60·2%) and less resistance to tetracycline (5·6-40·7%) were observed in the different groups of chickens. Antibiotic resistance genes bla(OXA-61,) cmeB and tet(O) were found in 82·6-92·7%, 80·3-89% and 22·3-30·9% Camp. coli isolates from pigs, whilst 59-65·4% and 19·2-40·7% Camp. jejuni from chickens were found to encode bla(OXA-61) and tet(O), respectively. No significant difference between isolates from free range egg layers and meat chickens (P resistance genes. In addition, pulsed field gel electrophoresis of selected resistant isolates from the poultry and pig revealed closely related clonal groups. Our results suggest the resistant strains are persisting environmental isolates that have been acquired by the different livestock species. Furthermore, the different treatment practices in poultry and pigs have resulted in differences in resistance profiles in Campylobacter isolates. © 2012 The Authors Journal of Applied Microbiology © 2012 The Society for Applied Microbiology.

  19. Complete Genome Sequences of Multidrug-Resistant Campylobacter jejuni Strain 14980A (Turkey Feces) and Campylobacter coli Strain 14983A (Housefly from a Turkey Farm), Harboring a Novel Gentamicin Resistance Mobile Element

    OpenAIRE

    Miller, William G.; Huynh, Steven; Parker, Craig T.; Niedermeyer, Jeffrey A.; Kathariou, Sophia

    2016-01-01

    Multidrug resistance (MDR) in foodborne pathogens is a major food safety and public health issue. Here we describe whole-genome sequences of two MDR strains of Campylobacter jejuni and Campylobacter coli from turkey feces and a housefly from a turkey farm. Both strains harbor a novel chromosomal gentamicin resistance mobile element.

  20. DAYA HAMBAT SARI TANAMAN OBAT TERHADAP PERTUMBUHAN BAKTERI STRAIN Methicillin Resistant Staphylococcus aureus (MRSA

    Directory of Open Access Journals (Sweden)

    Dwi Hilda Putri

    2016-09-01

    Full Text Available Staphylococcus aureus infection can be treated with Methicilin, β lactam class of antibiotics that have drug targets in the cell wall. Bacteria S. aureus that is resistant to methicillin called methicillin-resistant Staphylococcus aureus (MRSA. One alternative that can be used in strains of antibiotic-resistant bacteria that have this is to use medicinal plants. This study aimed to know the ability of medicinal plant extracts inhibit the growth of bacterial strains of MRSA. This kind of research is experimental research. Medicinal plants tested were Garlic, Turmeric, Aloe Vera, Daun Salam, Curcuma, Ginger, Betel Leaf and Alpinia galanga. As a control, which is used Amphicillin, β lactam antibiotic class. The method used to determine the diameter of inhibition area of medicinal plant extracts is paper diffusion method. The results showed that all medicinal plants can inhibit bacterial growth of MRSA strains characterized by the inhibition zone formed on each treatment. The ability of garlic and turmeric extract better than Amphicillin and other medicinal plants to inhibit bacterial growth of MRSA strains. Kata kunci: inhibit,  growth, bacteria, methicillin resistant staphylococcus aureus (MRSA

  1. Title: High-level cefotaxime-resistant Proteus mirabilis strain isolated ...

    African Journals Online (AJOL)

    oaca

    Standards Institute (CLSI) guidelines and revealed that this strain was resistant to expanded-spectrum β-lactams. Analysis of P. mirabilis FS6449 by double-disk synergy test yielded a positive result suggesting the production of ESBLs. Sonicate of the isolate hydrolysed cefotaxime and benzylpenicillin. Isoelectric focusing ...

  2. Effect of compressive strain on electric resistance of multi-wall carbon nanotube networks

    Czech Academy of Sciences Publication Activity Database

    Slobodian, P.; Říha, Pavel; Lengálová, A.; Olejník, R.; Kimmer, D.; Sáha, P.

    2011-01-01

    Roč. 6, č. 3 (2011), s. 294-304 ISSN 1745-8080 R&D Projects: GA AV ČR IAA200600803 Institutional research plan: CEZ:AV0Z20600510 Keywords : MWNT network * electric resistance * buckypaper * strain effect Subject RIV: JB - Sensors, Measurment, Regulation Impact factor: 1.011, year: 2011

  3. Complete genome sequence of an attenuated Sparfloxacin-resistant Streptococcus agalactiae strain 138spar

    Science.gov (United States)

    The complete genome of a sparfloxacin-resistant Streptococcus agalactiae vaccine strain 138spar is 1,838,126 bp in size. The genome has 1892 coding sequences and 82 RNAs. The annotation of the genome is added by the NCBI Prokaryotic Genome Annotation Pipeline. The publishing of this genome will allo...

  4. [Evaluation of the efficacy of colistin/sulbactam combination on carbapenem-resistant Acinetobacter baumannii strains].

    Science.gov (United States)

    Çetinkol, Yeliz; Telli, Murat; Altunçekiç Yıldırım, Arzu; Çalgın, Mustafa Kerem

    2016-07-01

    Acinetobacter baumannii strains, are opportunistic pathogens that cause severe nosocomial infections that are difficult to treat due to development of resistance to multiple antibiotics. As the antibiotic choices to be used in treatment are limited, combinations of a variety of antibiotics are used. The aims of this study were to identify the minimal inhibitory concentration (MIC) values of colistin and sulbactam against A.baumannii isolates and to determine the in vitro activity of colistin-sulbactam combination. A total of 50 A.baumannii strains isolated from different clinical specimens (32 tracheal aspirates, 10 blood, 6 urine and 2 wound samples) were included in the study. The identification of bacteria was performed by traditional methods and Vitek-2 (BioMerieux, France) automated system. Antibiotic susceptibilities were detected by Mueller-Hinton agar disk diffusion method and Vitek-2 automated system and the results were interpreted according to the CLSI standards. MIC values of colistin and sulbactam against A.baumannii strains and in vitro interactions of colistin-sulbactam combinations were determined with the E-test (BioMerieux, France). Fractional inhibitory concentration (FIC) index was used for the detection of efficacy of drug combinations. The presence of oxacillinase and metallo-beta-lactamase (MBL) genes that lead carbapenem resistance was investigated by polymerase chain reaction (PCR), and pulsed-field gel electrophoresis (PFGE) was performed for the determination of clonal relationship. In our study, all strains (100%) were detected as susceptible to colistin, 48 (96%) to trimethoprim/sulphamethoxazole and 18 to (36%) tigecyclin; however all of them were resistant to the other studied antibiotics, including sulbactam and carbapenem. When the colistin-sulbactam combination was assessed according to FIC index, all strains were found to have antagonistic effect. All of the carbapenem-resistant strains were positive for OXA-51 and OXA-23, and 3

  5. Rhizobium strains differ considerably in outer membrane permeability and polymyxin B resistance.

    Science.gov (United States)

    Komaniecka, Iwona; Zamłyńska, Katarzyna; Zan, Radosław; Staszczak, Magdalena; Pawelec, Jarosław; Seta, Irena; Choma, Adam

    2016-01-01

    Six rhizobium (Rhizobium leguminosarum bv. Trifolii TA1, Sinorhizobium meliloti 1021, Mesorhizobium huakuii IFO 15243(T), Ochrobactrum lupini LUP 21(T), Bradyrhizobium japonicum USDA110 and B. elkanii USDA 76) and two Escherichia coli strains (E. coli ATCC 25922 and E. coli HB 101) were compared in respect to polymyxin B and EDTA resistance, as well as bacterial outer membrane (OM) permeability to a fluorescent hydrophobic agent (N-phenyl-1-naphthylamine - NPN). TEM (Transmission Electron Microscopy) and a microbial test demonstrated that all the rhizobia were much more resistant to polymyxin B in comparison with E. coli strains. EDTA and polymyxin B enhance permeability of B. japonicum and O. lupini OM. Other rhizobia incorporated NPN independently of the presence of membrane-deteriorating agents; however, the level of fluorescence (measured as NPN absorption) was strain dependent.

  6. The survey of shigellosis frequency and determination of antibiotic resistance profile of isolated strains from infected children in Tehran

    Directory of Open Access Journals (Sweden)

    Shahla Abbaspour

    2014-04-01

    Full Text Available Background: Shigellosis is endemic throughout the world and it is among the most common causes of bacterial diarrheal diseases. Antibiotic resistance of Shigella is becoming a progressive problem in world. The aim of this study was the survey of shigellosis frequency and determination of antibiotic resistance profile of isolated strains from infected children in Tehran. Material and Methods: This study conducted on 9131 patients with acute diarrheal disease. For isolation of Shigella spp. from stool samples, culture performed on different selective and differential media. After confirmation of bacteria by biochemical tests, susceptibility testing was done by disc diffusion method according to clinical and laboratory standards (CLSI recomendations. Results: Among 9131 stool samples, Shigella spp. was isolated from 90 cases. Shigella sonnei was the most common isolated species. 92/2 % of isolates were resistant to cotrimoxazole. In contrast, most of the Shigella spp. was founded to be sensitive to ciprofloxacin, imipenem and third-generation cephalosporins. Conclusion: Surveillance programs on antimicrobial resistance not only identify pathogenic bacterial species, by reporting data like serotyping, microorganisms incidence rates, and susceptibility to the antimicrobial agents currently used for treatment, but also contribute to monitoring the intervention strategies including removing organism from reservoirs.

  7. Antiherpetic properties of acyclovir 5'-hydrogenphosphonate and the mutation analysis of herpes virus resistant strains.

    Science.gov (United States)

    Gus'kova, Anna A; Skoblov, Mikhail Yu; Korovina, Anna N; Yasko, Maxim V; Karpenko, Inna L; Kukhanova, Marina K; Andronova, Valeria L; Galegov, George A; Skoblov, Yuri S

    2009-10-01

    In this study, we continued to study antiherpetic properties of acyclovir 5'-hydrogenphosphonate (Hp-ACV) in cell cultures and animal models. Hp-ACV was shown to inhibit the development of herpetic infection in mice induced by the HSV-1/L(2) strain. The compound suppressed replication of both ACV-sensitive HSV-1/L(2) and ACV-resistant HSV-1/L(2)/R strains in Vero cell culture. Viral population resistant to Hp-ACV (HSV-1/L(2)/R(Hp-ACV)) was developed much slower than ACV-resistant population. The analysis of Hp-ACV-resistant clones isolated from the HSV-1/L(2)/R(Hp-ACV) population demonstrated their partial cross-resistance to ACV. The mutations determining the resistance of HSV-1 clones to Hp-ACV were partly overlapped with mutations defining ACV resistance but did not always coincide. HSV-1/L(2)/R(Hp-ACV) herpes virus thymidine kinase is shortened from the C-terminus by 100 amino acid residues in length.

  8. Microstructural origin of resistance-strain hysteresis in carbon nanotube thin film conductors.

    Science.gov (United States)

    Jin, Lihua; Chortos, Alex; Lian, Feifei; Pop, Eric; Linder, Christian; Bao, Zhenan; Cai, Wei

    2018-02-27

    A basic need in stretchable electronics for wearable and biomedical technologies is conductors that maintain adequate conductivity under large deformation. This challenge can be met by a network of one-dimensional (1D) conductors, such as carbon nanotubes (CNTs) or silver nanowires, as a thin film on top of a stretchable substrate. The electrical resistance of CNT thin films exhibits a hysteretic dependence on strain under cyclic loading, although the microstructural origin of this strain dependence remains unclear. Through numerical simulations, analytic models, and experiments, we show that the hysteretic resistance evolution is governed by a microstructural parameter [Formula: see text] (the ratio of the mean projected CNT length over the film length) by showing that [Formula: see text] is hysteretic with strain and that the resistance is proportional to [Formula: see text] The findings are generally applicable to any stretchable thin film conductors consisting of 1D conductors with much lower resistance than the contact resistance in the high-density regime.

  9. Silencing Agrobacterium oncogenes in transgenic grapevine results in strain-specific crown gall resistance.

    Science.gov (United States)

    Galambos, A; Zok, A; Kuczmog, A; Oláh, R; Putnoky, P; Ream, W; Szegedi, E

    2013-11-01

    Grapevine rootstock transformed with an Agrobacterium oncogene-silencing transgene was resistant to certain Agrobacterium strains but sensitive to others. Thus, genetic diversity of Agrobacterium oncogenes may limit engineering crown gall resistance. Crown gall disease of grapevine induced by Agrobacterium vitis or Agrobacterium tumefaciens causes serious economic losses in viticulture. To establish crown gall-resistant lines, somatic proembryos of Vitis berlandieri × V. rupestris cv. 'Richter 110' rootstock were transformed with an oncogene-silencing transgene based on iaaM and ipt oncogene sequences from octopine-type, tumor-inducing (Ti) plasmid pTiA6. Twenty-one transgenic lines were selected, and their transgenic nature was confirmed by polymerase chain reaction (PCR). These lines were inoculated with two A. tumefaciens and three A. vitis strains. Eight lines showed resistance to octopine-type A. tumefaciens A348. Resistance correlated with the expression of the silencing genes. However, oncogene silencing was mostly sequence specific because these lines did not abolish tumorigenesis by A. vitis strains or nopaline-type A. tumefaciens C58.

  10. Synergistic effect of eugenol with Colistin against clinical isolated Colistin-resistant Escherichia coli strains

    Directory of Open Access Journals (Sweden)

    Yi-ming Wang

    2018-01-01

    Full Text Available Abstract Background Bacterial infections have become more challenging to treat due to the emergence of multidrug-resistant pathogenic bacteria. Combined antibiotics prove to be a relatively effective method to control such resistant strains. This study aim to investigate synergistic activity of eugenol combined with colistin against a collection of clinical isolated Escherichia coli (E.coli strains, and to evaluate potential interaction. Methods Antimicrobial susceptibility, minimum inhibitory concentration (MIC and fractional inhibitory concentration index (FICI of the bacteria were determined by disk diffusion assay, broth microdilution method and checkerboard assay, respectively. The mcr-1 mRNA expression was measured by Real-time PCR. To predict possible interactions between eugenol and MCR-1, molecular docking assay was taken. Results For total fourteen strains including eight colistin-resistant strains, eugenol was determined with MIC values of 4 to 8 μg/mL. Checkerboard dilution test suggested that eugenol exhibited synergistic activity when combined with colistin (FICI ranging from 0.375 to 0.625. Comparison analysis of Real-time PCR showed that synergy could significantly down-regulate expression of mcr-1 gene. A metal ion coordination bond with catalytic zinc atom and a hydrogen bond with crucial amino acid residue Ser284 of MCR-1 were observed after molecular docking, indicating antibacterial activity and direct molecular interactions of eugenol with MCR-1 protein. Conclusions Our results demonstrated that eugenol exhibited synergistic effect with colistin and enhanced its antimicrobial activity. This might further contribute to the antibacterial actions against colistin-resistant E.coli strains. Graphical abstract Synergistic effect of eugenol with colistin against colistin-resistant Escherichia coli isolates.

  11. Soluble coxsackie- and adenovirus receptor (sCAR-Fc); a highly efficient compound against laboratory and clinical strains of coxsackie-B-virus.

    Science.gov (United States)

    Pinkert, Sandra; Dieringer, Babette; Diedrich, Sabine; Zeichhardt, Heinz; Kurreck, Jens; Fechner, Henry

    2016-12-01

    Coxsackie-B-viruses (CVB) cause a wide variety of diseases, ranging from mild syndromes to life-threatening conditions such as pancreatitis, myocarditis, meningitis and encephalitis. Especially newborns and young infants develop severe diseases and long-term sequelae may occur among survivors. Due to lack of specific antiviral therapy the current treatment of CVB infection is limited to symptomatic treatment. Here we analyzed the antiviral activity of a soluble receptor fusion protein, containing the extracellular part of the coxsackievirus and adenovirus receptor (CAR) fused to the constant domain of the human IgG - sCAR-Fc - against laboratory and clinical CVB strains. We found a high overall antiviral activity of sCAR-Fc against various prototypic laboratory strains of CVB, with an inhibition of viral replication up to 3 orders of magnitude (99.9%) at a concentration of 2.5 μg/ml. These include isolates that are not dependent on CAR for infection and isolates that are resistant against pleconaril, the currently most promising anti-CVB therapeutic. A complete inhibition was observed using higher concentration of sCAR-Fc. Further analysis of 23 clinical CVB isolates revealed overall high antiviral efficiency (up to 99.99%) of sCAR-Fc. In accordance with previous data, our results confirm the strong antiviral activity of sCAR-Fc against laboratory CVB strains and demonstrate for the first time that sCAR-Fc is also highly efficient at neutralizing clinical CVB isolates. Importantly, during the sCAR-Fc inhibition experiments, no naturally occurring resistant mutants were observed. Copyright © 2016 Elsevier B.V. All rights reserved.

  12. Evaluation of Bacillus thuringiensis Pathogenicity for a Strain of the Tick, Rhipicephalus microplus, Resistant to Chemical Pesticides

    Science.gov (United States)

    Fernández-Ruvalcaba, Manuel; Peña-Chora, Guadalupe; Romo-Martínez, Armando; Hernández-Velázquez, Víctor; de Parra, Alejandra Bravo; De La Rosa, Diego Pérez

    2010-01-01

    The pathogenicity of four native strains of Bacillus thuringiensis against Rhipicephalus (Boophilus) microplus (Canestrine) (Acari: Ixodidae) was evaluated. A R. microplus strain that is resistant to organophosphates, pyrethroids, and amidines, was used in this study. Adult R. microplus females were bioassayed using the immersion test of Drummond against 60 B. thuringiensis strains. Four strains, GP123, GP138, GP130, and GP140, were found to be toxic. For the immersion test, the total protein concentration for each bacterial strain was 1.25 mg/ml. Mortality, oviposition, and egg hatch were recorded. All of the bacterial strains had significant effects compared to the controls, but no significant differences were seen between the 4 strains. It is evident that these B. thuringiensis strains have a considerable detrimental effect on the R. microplus strain that is resistant to pesticides. PMID:21062139

  13. Amdinocillin (Mecillinam) Resistance Mutations in Clinical Isolates and Laboratory-Selected Mutants of Escherichia coli

    Science.gov (United States)

    Thulin, Elisabeth; Sundqvist, Martin

    2015-01-01

    Amdinocillin (mecillinam) is a β-lactam antibiotic that is used mainly for the treatment of uncomplicated urinary tract infections. The objectives of this study were to identify mutations that confer amdinocillin resistance on laboratory-isolated mutants and clinical isolates of Escherichia coli and to determine why amdinocillin resistance remains rare clinically even though resistance is easily selected in the laboratory. Under laboratory selection, frequencies of mutation to amdinocillin resistance varied from 8 × 10−8 to 2 × 10−5 per cell, depending on the concentration of amdinocillin used during selection. Several genes have been demonstrated to give amdinocillin resistance, but here eight novel genes previously unknown to be involved in amdinocillin resistance were identified. These genes encode functions involved in the respiratory chain, the ribosome, cysteine biosynthesis, tRNA synthesis, and pyrophosphate metabolism. The clinical isolates exhibited significantly greater fitness than the laboratory-isolated mutants and a different mutation spectrum. The cysB gene was mutated (inactivated) in all of the clinical isolates, in contrast to the laboratory-isolated mutants, where mainly other types of more costly mutations were found. Our results suggest that the frequency of mutation to amdinocillin resistance is high because of the large mutational target (at least 38 genes). However, the majority of these resistant mutants have a low growth rate, reducing the probability that they are stably maintained in the bladder. Inactivation of the cysB gene and a resulting loss of cysteine biosynthesis are the major mechanism of amdinocillin resistance in clinical isolates of E. coli. PMID:25583718

  14. [On the importance of multidrug-resistant strains of pathogenic microorganisms in ophthalmic practice].

    Science.gov (United States)

    Galeeva, G Z; Samoylov, A N; Rascheskov, A Yu

    2015-01-01

    This is a review of epidemiological, microbiological and ophthalmological publications on the importance of multidrug-resistant bacterial strains in medical, particularly ophthalmological, care. Current state of pharmaceutical market and wide variety of generics confuses doctor's (including ophthalmologist's) sense of decision-making on the optimum antibiotic for the treatment of purulent inflammation. Indiscriminate use of antibiotics contributes to multiple drug resistance in bacteria. The world returns to the pre-antibiotic era, in which there was no treatment for severe infectious and inflammatory diseases. The most dangerous multiresistant strains known to medical science and their role in etiology of inflammatory eye diseases are listed in the article. Since neonatal conjunctivitis and postoperative endophthalmitis are the most common ocular inflammatory diseases caused by nosocomial multiresistant bacteria, their etiological classification is also described. Emergence of antibiotic resistance to most frequently used ophthalmic agents and prevention strategies are discussed.

  15. Laboratory Evolution of a Biotin-Requiring Saccharomyces cerevisiae Strain for Full Biotin Prototrophy and Identification of Causal Mutations.

    Science.gov (United States)

    Bracher, Jasmine M; de Hulster, Erik; Koster, Charlotte C; van den Broek, Marcel; Daran, Jean-Marc G; van Maris, Antonius J A; Pronk, Jack T

    2017-08-15

    Biotin prototrophy is a rare, incompletely understood, and industrially relevant characteristic of Saccharomyces cerevisiae strains. The genome of the haploid laboratory strain CEN.PK113-7D contains a full complement of biotin biosynthesis genes, but its growth in biotin-free synthetic medium is extremely slow (specific growth rate [μ] ≈ 0.01 h -1 ). Four independent evolution experiments in repeated batch cultures and accelerostats yielded strains whose growth rates (μ ≤ 0.36 h -1 ) in biotin-free and biotin-supplemented media were similar. Whole-genome resequencing of these evolved strains revealed up to 40-fold amplification of BIO1 , which encodes pimeloyl-coenzyme A (CoA) synthetase. The additional copies of BIO1 were found on different chromosomes, and its amplification coincided with substantial chromosomal rearrangements. A key role of this gene amplification was confirmed by overexpression of BIO1 in strain CEN.PK113-7D, which enabled growth in biotin-free medium (μ = 0.15 h -1 ). Mutations in the membrane transporter genes TPO1 and/or PDR12 were found in several of the evolved strains. Deletion of TPO1 and PDR12 in a BIO1 -overexpressing strain increased its specific growth rate to 0.25 h -1 The effects of null mutations in these genes, which have not been previously associated with biotin metabolism, were nonadditive. This study demonstrates that S. cerevisiae strains that carry the basic genetic information for biotin synthesis can be evolved for full biotin prototrophy and identifies new targets for engineering biotin prototrophy into laboratory and industrial strains of this yeast. IMPORTANCE Although biotin (vitamin H) plays essential roles in all organisms, not all organisms can synthesize this vitamin. Many strains of baker's yeast, an important microorganism in industrial biotechnology, contain at least some of the genes required for biotin synthesis. However, most of these strains cannot synthesize biotin at all or do so at rates that are

  16. Whole-genome pyrosequencing of an epidemic multidrug-resistant Acinetobacter baumannii strain belonging to the European clone II group

    DEFF Research Database (Denmark)

    Iacono, M.; Villa, L.; Fortini, D.

    2008-01-01

    The whole-genome sequence of an epidemic, multidrug-resistant Acinetobacter baumannii strain (strain ACICU) belonging to the European clone II group and carrying the plasmid-mediated bla(OXA-58) carbapenem resistance gene was determined. The A. baumannii ACICU genome was compared with the genomes...

  17. Genetic analysis of extensively drug-resistant Mycobacterium tuberculosis strains in Lisbon, Portugal.

    Science.gov (United States)

    Perdigão, João; Macedo, Rita; Malaquias, Ana; Ferreira, Ana; Brum, Laura; Portugal, Isabel

    2010-02-01

    Extensively drug-resistant (XDR) tuberculosis (TB) threatens the global control of TB worldwide. Lisbon has a high XDR-TB rate [50% of the multidrug-resistant tuberculosis (MDR-TB)], which is mainly associated with Lisboa family strains. Few studies have addressed the identification of mutations associated with resistance to second-line injectable drugs, and the relative frequency of such mutations varies geographically. The aim of this study was to characterize the genetic changes associated with the high number of XDR-TB cases in Lisbon. In the present study we analysed 26 XDR-TB clinical isolates. The gyrA, tlyA and rrs genes were screened for mutations that could be responsible for resistance to fluoroquinolones and second-line injectable drugs. Moreover, the strains under analysis were also genotyped by MIRU-VNTR ('mycobacterial interspersed repetitive unit-variable number of tandem repeats'). The mutational analysis identified the most frequent mutations in the resistance-associated genes: S91P in gyrA (42.3%); A1401G in rrs (30.8%); and Ins755GT in tlyA (42.3%). The occurrence of mutations in rrs was associated with the non-occurrence of mutations in tlyA. The genotypic analysis revealed that the strains were highly clonal, belonging to one of two MIRU-VNTR clusters, with the largest belonging to the Lisboa family. Association between mutations in gyrA and rrs or tlyA was verified. The association of specific mutations highlighted the strains' high clonality and indicates recent XDR-TB transmission. In addition, the identification of the most frequent resistance-associated mutations will be invaluable in applying XDR-TB molecular detection tests in the region in the near future.

  18. Mechanism of Enhanced Activity of Liposome-Entrapped Aminoglycosides against Resistant Strains of Pseudomonas aeruginosa

    Science.gov (United States)

    Mugabe, Clement; Halwani, Majed; Azghani, Ali O.; Lafrenie, Robert M.; Omri, Abdelwahab

    2006-01-01

    Pseudomonas aeruginosa is inherently resistant to most conventional antibiotics. The mechanism of resistance of this bacterium is mainly associated with the low permeability of its outer membrane to these agents. We sought to assess the bactericidal efficacy of liposome-entrapped aminoglycosides against resistant clinical strains of P. aeruginosa and to define the mechanism of liposome-bacterium interactions. Aminoglycosides were incorporated into liposomes, and the bactericidal efficacies of both free and liposomal drugs were evaluated. To define the mechanism of liposome-bacterium interactions, transmission electron microscopy (TEM), flow cytometry, lipid mixing assay, and immunocytochemistry were employed. Encapsulation of aminoglycosides into liposomes significantly increased their antibacterial activity against the resistant strains used in this study (MICs of ≥32 versus ≤8 μg/ml). TEM observations showed that liposomes interact intimately with the outer membrane of P. aeruginosa, leading to the membrane deformation. The flow cytometry and lipid mixing assays confirmed liposome-bacterial membrane fusion, which increased as a function of incubation time. The maximum fusion rate was 54.3% ± 1.5% for an antibiotic-sensitive strain of P. aeruginosa and 57.8% ± 1.9% for a drug-resistant strain. The fusion between liposomes and P. aeruginosa significantly enhanced the antibiotics' penetration into the bacterial cells (3.2 ± 2.3 versus 24.2 ± 6.2 gold particles/bacterium, P ≤ 0.001). Our data suggest that liposome-entrapped antibiotics could successfully resolve infections caused by antibiotic-resistant P. aeruginosa through an enhanced mechanism of drug entry into the bacterial cells. PMID:16723560

  19. The antimicrobial activity of thyme essential oil against multidrug resistant clinical bacterial strains.

    Science.gov (United States)

    Sienkiewicz, Monika; Łysakowska, Monika; Denys, Paweł; Kowalczyk, Edward

    2012-04-01

    The aim of this work was to investigate the antimicrobial activity of thyme essential oil against clinical multidrug resistant strains of Staphylococcus, Enterococcus, Escherichia, and Pseudomonas genus. The antibacterial activity of oil was tested against standard strains of bacteria and 120 clinical strains isolated from patients with infections of the oral cavity, abdominal cavity, respiratory and genitourinary tracts, skin, and from the hospital environment. Agar diffusion was used to determine the microbial growth inhibition of bacterial growth at various concentrations of oil from Thymus vulgaris. Susceptibility testing to antibiotics was carried out using disk diffusion. Thyme essential oil strongly inhibited the growth of the clinical strains of bacteria tested. The use of phytopharmaceuticals based on an investigated essential oil from thyme in the prevention and treatment of various human infections may be reasonable.

  20. Mycobacteria: laboratory methods for testing drug sensitivity and resistance

    Science.gov (United States)

    Canetti, G.; Froman, S.; Grosset, J.; Hauduroy, P.; Langerová, Miloslava; Mahler, H. T.; Meissner, Gertrud; Mitchison, D. A.; Šula, L.

    1963-01-01

    In its seventh report, published in 1960, the WHO Expert Committee on Tuberculosis “noted the need for international standards for the definition and determination of drug resistance which will permit comparisons to be made from one area to another, and recommended that the World Health Organization take appropriate steps to establish such standards”.10 Acting on this recommendation, WHO took the first step towards standardization by convening in Geneva, in December 1961, an informal international meeting of specialists in the bacteriology of tuberculosis. At this meeting an attempt was made to formulate prerequisites for reliable sensitivity tests and to specify the technical procedures for them. The first part of the present paper is a joint contribution by the participants in the meeting, summarizing the general conclusions reached and recommendations made with regard to tests of sensitivity to the three main antituberculosis drugs—isoniazid, streptomycin and p-aminosalicylic acid. The other three parts describe, in turn, three different tests for determining drug sensitivity—the absolute-concentration method, the resistance-ratio method and the proportion method—that are generally considered to give reasonably accurate results. PMID:14102034

  1. Microalgal sensitivity varies between a diuron-resistant strain and two wild strains when exposed to diuron and irgarol, alone and in mixtures

    OpenAIRE

    Dupraz, Valentin; Coquille, Nathalie; Menard, Dominique; Sussarellu, Rossana; Haugarreau, Larissa; Stachowski-haberkorn, Sabine

    2016-01-01

    A wild strain of Chaetoceros calcitrans and wild and diuron-resistant strains of Tetraselmis suecica, were exposed to the PSII inhibitor herbicides diuron and irgarol, individually and in mixtures. The effects of three concentrations of diuron and irgarol and four binary mixtures were evaluated on doubling time, relative reactive oxygen species and lipid content by flow cytometry, and on photosynthetic efficiency by pulse amplitude modulated fluorescence. In both wild strains, significant...

  2. Antibiotic resistance patterns of coagulase-negative staphylococcus strains isolated from blood cultures of septicemic patients in Turkey.

    Science.gov (United States)

    Koksal, F; Yasar, H; Samasti, M

    2009-01-01

    The aim of this study is to determine antibiotic resistance patterns and slime production characteristics of coagulase-negative Staphylococci (CoNS) caused nosocomial bacteremia. A total of 200 CoNS strains were isolated from blood samples of patients with true bacteremia who were hospitalized in intensive care units and in other departments of Istanbul University Cerrahpasa Medical Hospital between 1999 and 2006. Among 200 CoNS isolates, Staphylococcus epidermidis was the most prevalent species (87) followed by Staphylococcus haemolyticus (23), Staphylococcus hominis (19), Staphylococcus lugdunensis (18), Staphylococcus capitis (15), Staphylococcus xylosus (10), Staphylococcus warneri (8), Staphylococcus saprophyticus (5), Staphylococcus lentus (5), Staphylococcus simulans (4), Staphylococcus chromogenes (3), Staphylococcus cohnii (1), Staphylococcus schleiferi (1), and Staphylococcus auricularis (1). Resistance to methicillin was detected in 67.5% of CoNS isolates. Methicillin-resistant CoNS strains were determined to be more resistant to antibiotics than methicillin-susceptible CoNS strains. Resistance rates of methicillin-resistant and methicillin-susceptible CoNS strains to the antibacterial agents, respectively, were as follows: gentamicin 90% and 17%, erythromycin 80% and 37%, clindamycin 72% and 18%, trimethoprim-sulfamethoxazole 68% and 38%, ciprofloxacin 67% and 23%, tetracycline 60% and 45%, chloramphenicol 56% and 13% and fusidic acid 25% and 15%. None of the strains were resistant to vancomycin and teicoplanin. Slime production was detected in 86 of 200 CoNS strains. Resistance to methicillin was found in 81% of slime-positive and in 57% of slime-negative strains. Our results indicated that there is a high level of resistance to widely used agents in causative methicillin-resistant CoNS strains. However fusidic acid has the smallest resistance ratio, with the exception of glycopeptides. Additionally, most S. epidermidis strains were slime

  3. ORIGINAL ARTICLE: Status of Methicillin Resistant Staphylococcus aureus Infections and Evaluation of PVL Producing Strains in Belgaum, South India

    Directory of Open Access Journals (Sweden)

    Harbhajan Kaur

    2012-07-01

    Full Text Available Background: Panton Valentine Leukocidin (PVL toxin, responsible for increased virulence and more severe infections can be found in both Methicillin-sensitive and Methicillin-resistant strains of Staphylococcus aureus (MSSA and MRSA. Aims & Objectives: To generate baseline data on the extent of MRSA infections and to estimate the frequency of PVL-positive S.aureus in Belgaum, South India. Material & Methods: 70 clinical isolates of S.aureus were obtained from various laboratories in Belgaum city. Theseisolates were identified, phenotypically characterized as MRSA/MSSA by disc diffusion method using oxacillin discs (1 µg and genetically by multiplex PCR for mecA and fem B genes. PCR was subsequently carried out on all isolates to detect LukS-PV and LukF-PV genes, the markers for potential producers of PVL toxin. Results: 27 out of 70 isolates (38.6% were confirmed as MRSA by PCR formecA. The prevalence of PVL gene was 85.1% and 48.8% in MRSA and MSSA respectively. The overall prevalence of PVL positive S.aureuswas 62.85%. Conclusion: Our study showed high percentage of PVL positive MRSA and MSSA, higher than the most reports worldwide. In the backdrop of bacterial strains gaining multiple drug resistance, our study warrants further epidemiological studies in hospitals and community levels in the region.

  4. SCCmec types and pvl gene in methicillin-resistant Staphylococcus aureus strains from children hospitalized in a tertiary care hospital in Mexico.

    Science.gov (United States)

    Borbón-Esquer, Eunice Mireya; Villaseñor-Sierra, Alberto; Martínez-López, Erika; Jáuregui-Lomeli, Juan José; Villaseñor-Martínez, Rosa; Ruiz-Briseño, Mariana Del Rocío

    2014-07-01

    The aim of this study was to determine the prevalence, SCCmec types, presence of the Panton-Valentine leukocidin (PVL) gene, and susceptibility to antibiotics of methicillin-resistant Staphylococcus aureus (MRSA) strains isolated from hospitalized children. From August 2009 to September 2011, 291 S. aureus strains were isolated from normally sterile body sites, of which 190 (65%) were MRSA. One hundred and two of the MRSA strains were genetically evaluated. SCCmec genotypes were identified by M-PCR and the PVL gene (pvl) by end-point PCR. Resistance to erythromycin, rifampicin, clindamycin, and trimethoprim-sulfamethoxazole (SXT) was assessed by Kirby-Bauer disk diffusion method in accordance with the Clinical and Laboratory Standards Institute guidelines of 2012. Of the 102 strains evaluated, 97 (95%) were SCCmec type II, 5 (5%) were SCCmec type IVa, and all (100%) were pvl-negative. Resistance to erythromycin, clindamycin, rifampicin, and SXT was 97%, 95%, 0%, and 0%, respectively. The prevalence of hospital-acquired MRSA was high. SCCmec type II was predominant and the pvl gene appeared not to play any role in the virulence of the MRSA strains from hospitalized children.

  5. satG, Conferring Resistance to Streptogramin A, Is Widely Distributed in Enterococcus faecium Strains but Not in Staphylococci

    Science.gov (United States)

    Haroche, Julien; Allignet, Jeanine; Aubert, Sylvie; Van Den Bogaard, Anthony E.; El Solh, Névine

    2000-01-01

    A gene almost identical to satG was isolated from an Enterococcus faecium strain. This gene was transferred to a Staphylococcus aureus recipient strain where it conferred resistance to streptogramin A. satG was found to be widely distributed among E. faecium strains but not detected among staphylococci. PMID:10602747

  6. Trend of antibiotic resistance of Vibrio cholerae strains from East Delhi.

    Science.gov (United States)

    Das, Shukla; Saha, Rumpa; Kaur, Iqbal R

    2008-05-01

    Epidemics of cholera caused by toxigenic Vibrio cholerae O1 and O139 (Bengal strain) represent a major public health problem in most developing countries. In view of the reported shift in epidemiology and pattern of antibiotic resistance in this was study carried out to assess the development of resistance to essential drugs like fluoroquinolones during treatment of cholera and cholera like cases in Delhi. Faecal specimens collected from 1184 patients with cholera and cholera like illness between 2001-2006 admitted to Guru Teg Bahadur hospital, East Delhi were subjected to culture isolation. Antimicrobial susceptibility testing of V. cholerae isolates was done by disc diffusion method. Of the 1184 faecal samples examined, 670 (56.6%) were positive for V. cholera from 2001- 2006. V. cholerae El Tor Ogawa (54.6%) was more common than serotype Inaba (32.5%). During 2004-2006 V. cholerae Inaba emerged as the predominant serotype. Resistance to nalidixic acid, furazolidone and co-trimoxazole was constantly high (100%). Multiple antibiotic resistance (MAR) V. cholerae O1 Inaba isolates exhibited increased resistance to ciprofloxacin with MIC >4 microg/ml, but largely all remained susceptible to other antibiotics like, gentamicin, tetracycline and chloramphenicol. V. cholerae have a permanent existence in the environment and during the quiescent period, their survival in water bodies allows dissipation of resistance patterns to different serotypes or strains of V. cholerae O1 and therefore there is need for constant observation.

  7. Frequency of resistance to penicillin and erythromycin of pneumococcal strains that caused ottis media

    Directory of Open Access Journals (Sweden)

    Jovanović Luka

    2017-01-01

    Full Text Available Introduction: Streptococcus pneumoniae is an important human pathogen and the most common cause of acute otitis media (AOM, especially in children. It is also a common cause of community acquired pneumonia, sepsis and bacterial meningitis. Drug of choice in the treatment of these disease are beta lactam antibiotics, and the first alternative are macrolides. The increasing prevalence of resistance to penicillin and macrolides, among pneumococci, has considerably complicated the treatment. Aim: The aim of this study was to determine susceptibility of pneumococcal isolates from pediatric AOM in Serbia to antibiotics. Material and methods: Antimicrobial susceptibility testing of 61 pneumococcal AOM was performed, collected from December 2014 to December 2015, using disk diffusion method and E test. Macrolide resistance profile was determined by double disk diffusion test. Results: In our study, 40 strains (65.6% showed reduced sensitivity to penicillin and erythromycin. There were 9 (14.8% high resistant isolates to penicillin, while 31 (50.8% showed reduced susceptibility. The most frequent resistance phenotype was cMLS. Co-resistance to penicillin and macrolides was found in 14.8% strains. Conclusion: Our results showed high resistance rate of S. pneumoniae, which causes AOM among children, to penicillin and macrolides. Further active surveillance of pneumococcal susceptibility to antibiotics is necessary, and use of these medications in empirical therapy should be limited.

  8. Antibiotic Resistance and Biofilm Production in Staphylococcus epidermidis Strains, Isolated from a Tertiary Care Hospital in Mexico City

    OpenAIRE

    Cabrera-Contreras, Roberto; Morelos-Ramírez, Rubén; Galicia-Camacho, Ada Nelly; Meléndez-Herrada, Enrique

    2013-01-01

    Staphylococcus epidermidis strains isolated from nosocomial infections represent a serious problem worldwide. In various Mexican states several reports have shown isolates from hospitals with antibiotic resistance to methicillin. In Mexico City, there is scarce information on staphylococcal infections in hospitals. Here, our research findings are shown in a four-year period study (2006?2010) for Staphylococcus epidermidis strains. Susceptibility and/or resistance to antibiotics in SE strains ...

  9. Design prediction of pavement skid resistance from laboratory tests

    Science.gov (United States)

    Parcells, W. H.; Metheny, T. M.; Maag, R. G.

    1980-08-01

    Methods for preevaluating aggregates and paving mixtures so that predictions can be made covering skid resistance properties of proposed and in service pavement types are discussed. A correlation was established between the field testing using the data from the British Portable Tester and the Locked Wheel Pavement Friction Trailer at speeds of 40 and 55 mph. Core samples were extracted from the Locked Wheel Tester Skid Path and subjected to wear on the small wheel circular track with periodic surface friction testing. The final step was to remix and remold the cored pavement samples or make samples with new materials to obtain an 'as new' surface and again subject these samples to wear on the small wheel circular track with periodic testing.

  10. Pathophysiologic, rather than laboratory-defined resistance drives aspirin failure in ischemic stroke.

    Science.gov (United States)

    Agayeva, Nergiz; Gungor, Levent; Topcuoglu, Mehmet Akif; Arsava, Ethem Murat

    2015-04-01

    A significant proportion of ischemic strokes occur while using aspirin and therefore can be considered as clinical aspirin resistance. Apart from this clinical description, aspirin resistance can be defined by laboratory tests of in vitro platelet reactivity. The correlation between clinical and laboratory-defined resistance, however, is far from perfect, and the heterogenous nature of stroke pathophysiology might play a role in this discrepancy. The level of in vitro platelet inhibition by aspirin was prospectively evaluated using the VerifyNow Aspirin Assay (Accumetrics, San Diego, CA) in patients presenting with ischemic stroke while using aspirin (n = 78). Demographic and clinical features, including stroke etiology, were compared among patients with and without sufficient level of platelet inhibition and an additional set of patients suffering from stroke while not using aspirin (n = 257). Similar analyses were performed in a separate validation cohort. Laboratory evidence of insufficient platelet inhibition was detected in 16 of 78 patients (21%) with clinical aspirin resistance. On the other hand, 30 patients (38%) had stroke etiologies well known to be inadequately responsive to aspirin therapy. Overall, laboratory-defined resistance by itself could be considered to be accountable for the ischemic event in only 15% of these patients. The corresponding figure was 9% in validation cohort. Patients with sufficient level of platelet inhibition were more likely to harbor an anticoagulant responsive etiology compared with aspirin naive patients (odds ratio, 2.0; P = .033). Our findings highlight that laboratory aspirin resistance because of insufficient platelet inhibition is relatively uncommon, whereas pathophysiologic resistance, signifying the presence of etiologies that cannot be efficiently treated with aspirin treatment, is a major contributor of clinical resistance in ischemic stroke. Copyright © 2015 National Stroke Association. Published by

  11. Effect of Bacteriophages on the Growth of Flavobacterium psychrophilum and Development of Phage-Resistant Strains

    DEFF Research Database (Denmark)

    Christiansen, Rói Hammershaimb; Madsen, Lone; Dalsgaard, Inger

    2016-01-01

    The controlling effect of single and multiple phages on the density of Flavobacterium psychrophilum at different initial multiplicity of infection (MOI) was assessed in batch cultures to explore the potential for phage-based treatment of this important fish pathogen. A high initial phage concentr...... is essential for fast and effective control of F. psychrophilum infection and suggest that the small populations of resistant clones had reduced competitive abilities relative to the sensitive ancestral strain.......The controlling effect of single and multiple phages on the density of Flavobacterium psychrophilum at different initial multiplicity of infection (MOI) was assessed in batch cultures to explore the potential for phage-based treatment of this important fish pathogen. A high initial phage...... and resistant strains were isolated for further characterization. The application of a mathematical model allowed simulation of phage-host interactions and resistance development, confirming indications from strain isolations that phage-sensitive strains dominated the regrowing population (>99.8 %) at low MOI...

  12. The msaABCR Operon Regulates Resistance in Vancomycin-Intermediate Staphylococcus aureus Strains

    Science.gov (United States)

    Samanta, Dhritiman

    2014-01-01

    Vancomycin-intermediate Staphylococcus aureus (VISA) strains present an increasingly difficult problem in terms of public health. However, the molecular mechanism for this resistance is not yet understood. In this study, we define the role of the msaABCR operon in vancomycin resistance in three clinical VISA strains, i.e., Mu50, HIP6297, and LIM2. Deletion of the msaABCR operon resulted in significant decreases in the vancomycin MIC (from 6.25 to 1.56 μg/ml) and significant reductions of cell wall thickness in strains Mu50 and HIP6297. Growth of the mutants in medium containing vancomycin at concentrations greater than 2 μg/ml resulted in decreases in the growth rate, compared with the wild-type strains. Mutation of the msaABCR operon also reduced the binding capacity for vancomycin. We conclude that the msaABCR operon contributes to resistance to vancomycin and cell wall synthesis in S. aureus. PMID:25155591

  13. Molecular detection and antimicrobial resistance of diarrheagenic Escherichia coli strains isolated from diarrheal cases

    International Nuclear Information System (INIS)

    Aslani, Mehdi M.; Salmanzadeh-Ahrabi, S.; Jafari, F.; Zali, Reza M.; Mani, M.; Alikhani, Yousef M.

    2008-01-01

    Objective was to identify and classify Iranian isolates of diarrheagenic Escherichia coli (E. coli) on the basis of presence of virulence genes and to determine antibiotic susceptibility of isolated strains. The current cross-sectional study was conducted in 2005 at the Pasteur Institute, Tehran, Iran. One hundred and ninety-three diarrheagenic E. coli isolated from diarrheal patients in different regions of Iran were included in current study. Virulence factors genees for diarrheagenic E. coli were detected by polymerase chain reaction. Of the 193 diarrheagenic E. coli detected by PCR, 86(44.5%) were Shiga toxin-producing E. coli (STEC), 74 (38.4%) enteropathogenic E. coli (EPEC), 19 (9.8%) enteroaggregative E. coli and 14 (7.3%) enterotoxigenic E. coli isolates. Susceptibility to 12 clinically important antimicrobial agents was determined for 193 strains of diarrhheagenic E. coli. A high incidence of resistance to tetracycline (63%), ampicillin (62%), streptomycin (56%), amoxicillin/clavulanic acid (44.5%), trimetoprim/sulphamethoxazole (39.5%) and cephalothin (37%) was observed. The STEC and EPEC strains with high resistance to tetracycline and ampicillin but highly susceptible to quinolones are among the most important causative agent of diarrhea in Iran. This study suggests that antimicrobial resistance is wide spread among E. coli strains colonizing Iranian patients. Guidelines for appropriate use of antibiotics in developing countries require updating. (author)

  14. Resistance to Antibiotics in Strains of Staphylococcus spp., Enterococcus spp. and Escherichia coli Isolated from Rectal Swabs of Pigs

    Directory of Open Access Journals (Sweden)

    M. Kolář

    2008-01-01

    Full Text Available The study aimed at determining the level of resistance of selected bacterial species (Staphylococcus spp., Enterococcus spp., Escherichia coli isolated from rectal swabs of pigs to antimicrobial agents. The tested strains were isolated from piglets aged 7 to 30 days. Bacterial species were identified by standard microbiological techniques and susceptibility to antibiotics was determined quantitatively by the standard microdilution method. Resistance of the Staphylococcus aureus strain to oxacillin was confirmed by detection of the mecA gene and PBP2a. A total of 115 Staphylococcus spp. isolates were collected. In the case of Staphylococcus aureus, the methicillin-resistant strain (MRSA was identified. Moreover, higher frequency of coagulase-negative staphylococci with minimum inhibitory concentration of oxacillin ≥ 0.5 mg/l was noticed. Inducible resistance to clindamycin in the Staphylococcus hominis strain was also detected. The strains of Enterococcus spp. (61 isolates exhibited high resistance to tetracycline (98.5%, erythromycin (86.8% and chloramphenicol (54.4%. Vancomycin-resistant enterococci were not isolated. In the case of Escherichia coli strains (111 isolates, higher frequency of resistant strains to tetracycline (81.1% and ampicillin (62.2% was documented. Resistance to fluoroquinolones and production of broad-spectrum β-lactamases was not noticed. The presented study may be considered as a pilot project assessing the prevalence of resistant bacteria in piglets kept on a single farm. It demonstrated the presence of resistant strains of Staphylococcus spp., including one MRSA strain, Enterococcus spp. and Escherichia coli. These strains may be present as a result of postnatal colonization with both bacterial microflora of dams and environmental microflora.

  15. Detection of Integrons and Staphylococcal Cassette ChromosomemecTypes in Clinical Methicillin-resistant Coagulase Negative Staphylococci Strains.

    Science.gov (United States)

    Hajiahmadi, Fahimeh; Ghale, Elham Salimi; Alikhani, Mohammad Yousef; Mordadi, Alireza; Arabestani, Mohammad Reza

    2017-02-01

    Integrons are thought to play an important role in the spread of antibiotic resistance. This study investigates class 1 and 2 integron-positive methicillin-resistant coagulase-negative staphylococci strains isolated in Iran and characterizes their patterns of antimicrobial resistance. Hundred clinical isolates of coagulase-negative staphylococci were characterized for integron content and staphylococcal cassette chromosome mec (SCCmec) type. Sixteen isolates carried class 1 ( intI1 ) integrons and four isolates carried class 2 ( intI2 ) integrons. One resistance gene array was identified among the class 1 integrons ( aadA1 cassette). The distribution of SCCmec types in 50 methicillin-resistant coagulase-negative staphylococci strains showed that SCCmec types III and V dominated among the tested strains. This is the first report of methicillin-resistant coagulase-negative staphylococci strains that carry two mobile genetic elements, including class 1 and 2 integrons and SCCmec, in Iran.

  16. Effect of gamma radiation on the adults and larvae of susceptible and insecticide resistant strains of Tribolium castaneum (Herbst)

    International Nuclear Information System (INIS)

    Bhatia, Parvathy; Sethi, G.R.

    1978-01-01

    Susceptibility of insecticide resistant strains of Tribolium castaneum (Herbst) to gamma radiation was evaluated in adult and larval stages. One susceptible (S) and three resistant strains viz., lindane-resistant (LR), DDT-resistant (DR) and malathion resistant (MR) were used. In the case of adults the LD 50 values, i.e., dose of gamma radiation required for 50 percent mortality 12 days after irradiation for different strains was: S 7798, LR 9120, DR 9772 and MR 8128 rads. In the case of 10 days old larvae the LD 50 values based on mortality 10 days after irradiation were : S 5105, LR 5821, DR 4375 and MR 5483 rads. The results showed that resistance to lindane, DDT and malathion in T. castaneum did not involve any significant change in the susceptibility of these strains to gamma radiation. (author)

  17. Standard test methods for performance characteristics of metallic bonded resistance strain gages

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    1992-01-01

    1.1 The purpose of this standard is to provide uniform test methods for the determination of strain gauge performance characteristics. Suggested testing equipment designs are included. 1.2 Test Methods E 251 describes methods and procedures for determining five strain gauge parameters: Section Part I—General Requirements 7 Part II—Resistance at a Reference Temperature 8 Part III—Gauge Factor at a Reference Temperature 9 Part IV—Temperature Coefficient of Gauge Factor\t10 Part V—Transverse Sensitivity\t11 Part VI—Thermal Output\t12 1.3 Strain gauges are very sensitive devices with essentially infinite resolution. Their response to strain, however, is low and great care must be exercised in their use. The performance characteristics identified by these test methods must be known to an acceptable accuracy to obtain meaningful results in field applications. 1.3.1 Strain gauge resistance is used to balance instrumentation circuits and to provide a reference value for measurements since all data are...

  18. Morphological Characteristics of Schistosoma mansoni PZQ-Resistant and -Susceptible Strains Are Different in Presence of Praziquantel

    Science.gov (United States)

    Pinto-Almeida, António; Mendes, Tiago; de Oliveira, Rosimeire Nunes; Corrêa, Sheila de Andrade Penteado; Allegretti, Silmara Marques; Belo, Silvana; Tomás, Ana; Anibal, Fernanda de Freitas; Carrilho, Emanuel; Afonso, Ana

    2016-01-01

    Schistosomiasis is one of the most common human parasitic diseases whose socioeconomic impact is only surpassed by malaria. Praziquantel (PZQ) is the only drug commercially available for the treatment of all schistosome species causing disease in humans. However, there has been stronger evidences of PZQ-resistance on Schistosoma mansoni and thus it is very important to study the phenotypic characteristics associated with it. The aim of this study was to evaluate morphological alterations in S. mansoni PZQ-resistant adult worms and eggs, by comparing a PZQ- resistant strain obtained under PZQ drug pressure with a PZQ-susceptible strain. For this, scanning electronic microscopy was used to assess tegumental responsiveness of both strains under PZQ exposure, and optical microscopy allowed the monitoring of worms and eggs in the presence of the drug. Those assays showed that PZQ-susceptible worms exposed to the drug had more severe tegumental damages than the resistant one, which had only minor alterations. Moreover, contrary to what occurred in the susceptible strain, resistant worms were viable after PZQ exposure and gradually regaining full motility after removal of the drug. Eggs from resistant strain parasites are considerably smaller than those from susceptible strain. Our results suggest that there might be a difference in the tegument composition of the resistant strain and that worms are less responsive to PZQ. Changes observed in egg morphology might imply alterations in the biology of schistosomes associated to PZQ-resistance, which could impact on transmission and pathology of the disease. Moreover, we propose a hypothetical scenario where there is a different egg tropism of the S. mansoni resistant strain. This study is the first comparing two strains that only differ in their resistance characteristics, which makes it a relevant step in the search for resistance determinants. PMID:27199925

  19. High Affinity Inha Inhibitors with Activity Against Drug-Resistant Strains of Mycobacterium Tuberculosis

    Energy Technology Data Exchange (ETDEWEB)

    Sullivan,T.; Truglio, J.; Boyne, M.; Novichenok, P.; Zhang, X.; Stratton, C.; Li, H.; Kaur, T.; Amin, A.; et al.

    2006-01-01

    Novel chemotherapeutics for treating multidrug-resistant (MDR) strains of Mycobacterium tuberculosis (MTB) are required to combat the spread of tuberculosis, a disease that kills more than 2 million people annually. Using structure-based drug design, we have developed a series of alkyl diphenyl ethers that are uncompetitive inhibitors of InhA, the enoyl reductase enzyme in the MTB fatty acid biosynthesis pathway. The most potent compound has a Ki{prime} value of 1 nM for InhA and MIC{sub 99} values of 2-3 {micro}g mL{sup -1} (6-10 {micro}M) for both drug-sensitive and drug-resistant strains of MTB. Overexpression of InhA in MTB results in a 9-12-fold increase in MIC{sub 99}, consistent with the belief that these compounds target InhA within the cell. In addition, transcriptional response studies reveal that the alkyl diphenyl ethers fail to upregulate a putative efflux pump and aromatic dioxygenase, detoxification mechanisms that are triggered by the lead compound triclosan. These diphenyl ether-based InhA inhibitors do not require activation by the mycobacterial KatG enzyme, thereby circumventing the normal mechanism of resistance to the front line drug isoniazid (INH) and thus accounting for their activity against INH-resistant strains of MTB.

  20. Silver Nanocomposite Biosynthesis: Antibacterial Activity against Multidrug-Resistant Strains of Pseudomonas aeruginosa and Acinetobacter baumannii

    Directory of Open Access Journals (Sweden)

    Klebson Silva Santos

    2016-09-01

    Full Text Available Bacterial resistance is an emerging public health issue that is disseminated worldwide. Silver nanocomposite can be an alternative strategy to avoid Gram-positive and Gram-negative bacteria growth, including multidrug-resistant strains. In the present study a silver nanocomposite was synthesized, using a new green chemistry process, by the addition of silver nitrate (1.10−3 mol·L−1 into a fermentative medium of Xanthomonas spp. to produce a xanthan gum polymer. Transmission electron microscopy (TEM was used to evaluate the shape and size of the silver nanoparticles obtained. The silver ions in the nanocomposite were quantified by flame atomic absorption spectrometry (FAAS. The antibacterial activity of the nanomaterial against Escherichia coli (ATCC 22652, Enterococcus faecalis (ATCC 29282, Pseudomonas aeruginosa (ATCC 27853 and Staphylococcus aureus (ATCC 25923 was carried out using 500 mg of silver nanocomposite. Pseudomonas aeruginosa and Acinetobacter baumannii multidrug-resistant strains, isolated from hospitalized patients were also included in the study. The biosynthesized silver nanocomposite showed spherical nanoparticles with sizes smaller than 10 nm; 1 g of nanocomposite contained 49.24 µg of silver. Multidrug-resistant strains of Pseudomonas aeruginosa and Acinetobacter baumannii, and the other Gram-positive and Gram-negative bacteria tested, were sensitive to the silver nanocomposite (10–12.9 mm of inhibition zone. The biosynthesized silver nanocomposite seems to be a promising antibacterial agent for different applications, namely biomedical devices or topical wound coatings.

  1. PCR-based identification of methicillin–resistant Staphylococcus aureus strains and their antibiotic resistance profiles

    Directory of Open Access Journals (Sweden)

    Abazar Pournajaf

    2014-05-01

    Conclusions: This study is suggestive that the PCR for detection of mecA gene is a fast, accurate and valuable diagnostic tool, particularly in hospitals in areas where methicillin-resistant S. aureus is endemic.

  2. Sensitivity to Lovastatin of Saccharomyces cerevisiae Strains Deleted for Pleiotropic Drug Resistance (PDR) Genes

    DEFF Research Database (Denmark)

    Formenti, Luca Riccardo; Kielland-Brandt, Morten

    2011-01-01

    The use of statins is well established in human therapy, and model organisms such as Saccharomyces cerevisiae are commonly used in studies of drug action at molecular and cellular levels. The investigation of the resistance mechanisms towards statins may suggest new approaches to improve therapy...... based on the use of statins. We investigated the susceptibility to lovastatin of S. cerevisiae strains deleted for PDR genes, responsible for exporting hydrophobic and amphi-philic drugs, such as lovastatin. Strains deleted for the genes tested, PDR1, PDR3, PDR5 and SNQ2, exhibited remarkably different...

  3. Extended-Spectrum Cephalosporin-Resistant Salmonella enterica serovar Heidelberg Strains, the Netherlands1

    Science.gov (United States)

    Geurts, Yvon; Dierikx, Cindy M.; Brouwer, Michael S.M.; Kant, Arie; Wit, Ben; Heymans, Raymond; van Pelt, Wilfrid; Mevius, Dik J.

    2016-01-01

    Extended-spectrum cephalosporin-resistant Salmonella enterica serovar Heidelberg strains (JF6X01.0022/XbaI.0251, JF6X01.0326/XbaI.1966, JF6X01.0258/XbaI.1968, and JF6X01.0045/XbaI.1970) have been identified in the United States with pulsed-field gel electrophoresis. Our examination of isolates showed introduction of these strains in the Netherlands and highlight the need for active surveillance and intervention strategies by public health organizations. PMID:27314180

  4. Extended-Spectrum Cephalosporin-Resistant Salmonella enterica serovar Heidelberg Strains, the Netherlands(1).

    Science.gov (United States)

    Liakopoulos, Apostolos; Geurts, Yvon; Dierikx, Cindy M; Brouwer, Michael S M; Kant, Arie; Wit, Ben; Heymans, Raymond; van Pelt, Wilfrid; Mevius, Dik J

    2016-07-01

    Extended-spectrum cephalosporin-resistant Salmonella enterica serovar Heidelberg strains (JF6X01.0022/XbaI.0251, JF6X01.0326/XbaI.1966, JF6X01.0258/XbaI.1968, and JF6X01.0045/XbaI.1970) have been identified in the United States with pulsed-field gel electrophoresis. Our examination of isolates showed introduction of these strains in the Netherlands and highlight the need for active surveillance and intervention strategies by public health organizations.

  5. Efficient recovery of fluoroquinolone-susceptible and fluoroquinolone-resistant Escherichia coli strains from frozen samples.

    Science.gov (United States)

    Lautenbach, Ebbing; Santana, Evelyn; Lee, Abby; Tolomeo, Pam; Black, Nicole; Babson, Andrew; Perencevich, Eli N; Harris, Anthony D; Smith, Catherine A; Maslow, Joel

    2008-04-01

    We assessed the rate of recovery of fluoroquinolone-resistant and fluoroquinolone-susceptible Escherichia coli isolates from culture of frozen perirectal swab samples compared with the results for culture of the same specimen before freezing. Recovery rates for these 2 classes of E. coli were 91% and 83%, respectively. The majority of distinct strains recovered from the initial sample were also recovered from the frozen sample. The strains that were not recovered were typically present only in low numbers in the initial sample. These findings emphasize the utility of frozen surveillance samples.

  6. Antibiotic resistance in uropathogenic e. Coli strains isolated from non-hospitalized patients in pakistan.

    Science.gov (United States)

    Ali, Ihsan; Kumar, Neeraj; Ahmed, Safia; Dasti, Javid Iqbal

    2014-09-01

    To study multidrug-resistance in Uropathogenic E. Coli (UPEC) isolated from non-hospitalized patients. Altogether, 250 bacterial samples were collected from non-hospitalized patients. Their identifications were done on basis of Gram-staining, colony morphology, biochemical testing and PCR. Susceptibility testing was performed by using standard protocols which were recommended by CLSI. For comparisons, statistical analysis was performed by using software, Graphpad Prism 5.0 RESULTS: In total, 32% (n = 80) of the isolates were identified as E. Coli strains and their susceptibility patterns for different antibiotics were determined. The data indicated least resistance against tazocin [(TZP) -1.25%], amikacin [(AK) -1.8%], tigecycline [(TGC)- 2.5%] and nitrofurantoin [(F) -3.75%]. For both minocycline (MH) and sulzone (SUL), resistance rate was 5%, for gentamicin (CN), it was 16.25%, while higher resistances were observed against cephalothine [(KF)- 70%], cefotaxime [(CTX) -58.5%], ceftazidime [(CAZ)- 57.5%], cefepime [(FEP) -55%], cefuroxime and cefixime [(CXM) (CFM)- 53.75 %]. Resistance against ciprofloxacin (CIP) was 57.5%, for norfloxacine (NOR), it was 52.5% and incase of sparfloxacin (SPX), it remained 55%. High percentage of the isolates were resistant to cotrimoxazole [(SXT) -86%] and Amoxicillin [AMX-CLA (AMC)- 76%]. No resistance against meropenem (MEM) was observed. Highest level of drug-resistance was observed against trimethoprim-sulfamethoxazole (TMP-SMZ) among clinical isolates of uropathogenic E. Coli collected from non-hospitalized patients.

  7. Toxigenic genes, spoilage potential, and antimicrobial resistance of Bacillus cereus group strains from ice cream.

    Science.gov (United States)

    Arslan, Seza; Eyi, Ayla; Küçüksarı, Rümeysa

    2014-02-01

    Bacillus spp. can be recovered from almost every environment. It is also found readily in foods, where it may cause food spoilage and/or food poisoning due to its toxigenic and pathogenic nature, and extracellular enzymes. In this study, 29 Bacillus cereus group strains from ice cream were examined for the presence of following virulence genes hblC, nheA, cytK and ces genes, and tested for a range of the extracellular enzymes, and antimicrobial susceptibility. The strains were found to produce extracellular enzymes: proteolytic and lipolytic activity, gelatin hydrolysis and lecithinase production (100%), DNase production (93.1%) and amylase activity (93.1%). Of 29 strains examined, 24 (82.8%) showed hemolytic activity on blood agar. Beta-lactamase enzyme was only produced by 20.7% of B. cereus group. Among 29 B. cereus group from ice cream, nheA was the most common virulence gene detected in 44.8% of the strains, followed by hblC gene with 17.2%. Four (13.8%) of the 29 strains were positive for both hblC gene and nheA gene. Contrarily, cytK and ces genes were not detected in any of the strains. Antimicrobial susceptibility of ice cream isolates was tested to 14 different antimicrobial agents using the disc diffusion method. We detected resistance to penicillin and ampicillin with the same rate of 89.7%. Thirty-one percent of the strains were multiresistant to three or more antibiotics. This study emphasizes that the presence of natural isolates of Bacillus spp. harboring one or more enterotoxin genes, producing extracellular enzymes which may cause spoilage and acquiring antibiotic resistance might hold crucial importance in the food safety and quality. Copyright © 2013 Elsevier Ltd. All rights reserved.

  8. [Resistance to ciprofloxacin of Neisseria gonorrhoeae strains isolated in Poland in 2012-2013].

    Science.gov (United States)

    Młynarczyk-Bonikowska, Beata; Kujawa, Marlena; Młynarczyk, Grażyna; Malejczyk, Magdalena; Majewski, Sławomir

    2014-01-01

    Ciprofloxacin is commonly used in Poland specially for the treatment of urinary tract infections including urethritis. Patients are often treated without pathogen identification and antimicrobial resistance tests. Neisseria gonorrhoeae infection is one of the most common causes of urethritis in Poland. The resistance of bacteria to a wide range of antibiotics including ciprofloxacine makes the therapy of gonorrhoea more difficult. The mechanism of ciprofloxacine action depends on inactivation of bacterial topoisomerase II (gyrase) and topoisomerase IV. A resistance to ciprofloxacine occurring in Neisseria gonorrhoeae is mainly due to mutations in bacterial gyrA (encoding topoisomerase II) and/or parC (encoding topoisomerase IV ) genes. High level resistance is an effect of combination of three or four mutations. Another, less important mechanism of ciprofloxacin resistance, that can coexist with mutations in gyrA and parC genes related to the overproduction of membrane pumps proteins. 65 Neisseria gonorrhoeae strains isolated from patients of Department of Dermatology and Wenereology in Warsaw in the second half of 2012 and first of 2013 was investigated. The strains were cultured on chocolate agar plates in a 5% CO2 atmosphere at 37 degrees C and identified by colony morphology, Gram stain and oxidase reaction, followed by carbohydrate utilization test. Ciprofloxacin susceptibility was determined by E-Tests (bioMerieux). Bacteria were incubated at 35 degrees C in 5% CO2 for 24 h on chocolate agar plates. Tests were performed according to producers recommendations. The results (sensitive or resistant) were interpreted according to EUCAST recommendations. The MIC (Minimal inhibitory concentration) of Ciprofloxacin in investigated strains ranged from 0,002 to > 32 mg/L, MIC50 = 8 mg/L, MIC90 = > 32 mg/L. It was shown that only 38.5% of the strains were sensitive to ciprofloxacin according to EUCAST criteria from 2013 year. Due to the high percentage of ciprofloxacin

  9. Reduced Maximal Inhibition in Phenotypic Susceptibility Assays Indicates that Viral Strains Resistant to the CCR5 Antagonist Maraviroc Utilize Inhibitor-Bound Receptor for Entry▿

    Science.gov (United States)

    Westby, Mike; Smith-Burchnell, Caroline; Mori, Julie; Lewis, Marilyn; Mosley, Michael; Stockdale, Mark; Dorr, Patrick; Ciaramella, Giuseppe; Perros, Manos

    2007-01-01

    Maraviroc is a CCR5 antagonist in clinical development as one of a new class of antiretrovirals targeting human immunodeficiency virus type 1 (HIV-1) coreceptor binding. We investigated the mechanism of HIV resistance to maraviroc by using in vitro sequential passage and site-directed mutagenesis. Serial passage through increasing maraviroc concentrations failed to select maraviroc-resistant variants from some laboratory-adapted and clinical isolates of HIV-1. However, high-level resistance to maraviroc was selected from three of six primary isolates passaged in peripheral blood lymphocytes (PBL). The SF162 strain acquired resistance to maraviroc in both treated and control cultures; all resistant variants were able to use CXCR4 as a coreceptor. In contrast, maraviroc-resistant virus derived from isolates CC1/85 and RU570 remained CCR5 tropic, as evidenced by susceptibility to the CCR5 antagonist SCH-C, resistance to the CXCR4 antagonist AMD3100, and an inability to replicate in CCR5 Δ32/Δ32 PBL. Strain-specific mutations were identified in the V3 loop of maraviroc-resistant CC1/85 and RU570. The envelope-encoding region of maraviroc-resistant CC1/85 was inserted into an NL4-3 background. This recombinant virus was completely resistant to maraviroc but retained susceptibility to aplaviroc. Reverse mutation of gp120 residues 316 and 323 in the V3 loop (numbering from HXB2) to their original sequence restored wild-type susceptibility to maraviroc, while reversion of either mutation resulted in a partially sensitive virus with reduced maximal inhibition (plateau). The plateaus are consistent with the virus having acquired the ability to utilize maraviroc-bound receptor for entry. This hypothesis was further corroborated by the observation that a high concentration of maraviroc blocks the activity of aplaviroc against maraviroc-resistant virus. PMID:17182681

  10. Reduced maximal inhibition in phenotypic susceptibility assays indicates that viral strains resistant to the CCR5 antagonist maraviroc utilize inhibitor-bound receptor for entry.

    Science.gov (United States)

    Westby, Mike; Smith-Burchnell, Caroline; Mori, Julie; Lewis, Marilyn; Mosley, Michael; Stockdale, Mark; Dorr, Patrick; Ciaramella, Giuseppe; Perros, Manos

    2007-03-01

    Maraviroc is a CCR5 antagonist in clinical development as one of a new class of antiretrovirals targeting human immunodeficiency virus type 1 (HIV-1) coreceptor binding. We investigated the mechanism of HIV resistance to maraviroc by using in vitro sequential passage and site-directed mutagenesis. Serial passage through increasing maraviroc concentrations failed to select maraviroc-resistant variants from some laboratory-adapted and clinical isolates of HIV-1. However, high-level resistance to maraviroc was selected from three of six primary isolates passaged in peripheral blood lymphocytes (PBL). The SF162 strain acquired resistance to maraviroc in both treated and control cultures; all resistant variants were able to use CXCR4 as a coreceptor. In contrast, maraviroc-resistant virus derived from isolates CC1/85 and RU570 remained CCR5 tropic, as evidenced by susceptibility to the CCR5 antagonist SCH-C, resistance to the CXCR4 antagonist AMD3100, and an inability to replicate in CCR5 Delta32/Delta32 PBL. Strain-specific mutations were identified in the V3 loop of maraviroc-resistant CC1/85 and RU570. The envelope-encoding region of maraviroc-resistant CC1/85 was inserted into an NL4-3 background. This recombinant virus was completely resistant to maraviroc but retained susceptibility to aplaviroc. Reverse mutation of gp120 residues 316 and 323 in the V3 loop (numbering from HXB2) to their original sequence restored wild-type susceptibility to maraviroc, while reversion of either mutation resulted in a partially sensitive virus with reduced maximal inhibition (plateau). The plateaus are consistent with the virus having acquired the ability to utilize maraviroc-bound receptor for entry. This hypothesis was further corroborated by the observation that a high concentration of maraviroc blocks the activity of aplaviroc against maraviroc-resistant virus.

  11. Molecular Characteristics of Erythromycin-Resistant Streptococcus pyogenes Strains Isolated from Children Patients in Tunis, Tunisia.

    Science.gov (United States)

    Ksia, Sonia; Smaoui, Hanen; Hraoui, Manel; Bouafsoun, Aida; Boutiba-Ben Boubaker, Ihem; Kechrid, Amel

    2017-07-01

    The aims of our study were to characterize phenotypically and genotypically erythromycin-resistant Streptococcus pyogenes or group A streptococci (ERGAS) isolates, to evaluate macrolide resistance and to analyze the association between emm types and virulence factors. Included in this study were all ERGAS strains isolated from 2000 to 2013 at the Children's hospital of Tunis. Antimicrobial susceptibility was performed according to the CA-SFM guidelines. Macrolide resistance genes were revealed by polymerase chain reaction (PCR) method. Virulence factor genes (pyrogenic exotoxin genes and superantigen gene) were detected by PCR, and the emm types were defined by the sequencing of the variable 5' end of the emm gene. Among the 289 GAS isolates collected, 15 (5.2%) were resistant to erythromycin; 7 of the strains were assigned to the cMLS B phenotype (46.6%); 5 harbored ermB gene alone (33.3%); and 2 strains coharbored ermB and mefA (13.3%). The remaining (53.4%) were assigned to the M phenotype and harbored the mefA gene. The frequency of detection of each toxin gene among ERGAS was 13.4% for speA (2 strains), 53.4% for speC (8 strains), and 13.4% for ssa (2 strains). Emm types 1, 58, 11, and 78 were the most frequent among ERGAS strains. The distribution of the cMLS B and M phenotypes changed over the period of investigation with a decrement of cMLS B phenotype and ermB gene that predominated between 2000 and 2006 and an increase of M phenotype and mefA gene between 2007 and 2013, but this difference was nonstatistically significant because of the low number of resistant strains. Emm types 1, 58, and 4 were only present among strains assigned to the M phenotype. However strains assigned to the cMLS B phenotype were associated to emm11, emm22, emm28, emm78, or emm76. There was diversity in emm distribution in ERGAS between the two study periods. There was diversity in emm distribution among ERGAS particularly in 2000-2006. Indeed, from 2000 to 2006, the 6 ERGAS

  12. Evaluation of Bacillus thuringiensis Pathogenicity for a Strain of the Tick, Rhipicephalus microplus, Resistant to Chemical Pesticides

    OpenAIRE

    Fern?ndez-Ruvalcaba, Manuel; Pe?a-Chora, Guadalupe; Romo-Mart?nez, Armando; Hern?ndez-Vel?zquez, V?ctor; de Parra, Alejandra Bravo; De La Rosa, Diego P?rez

    2010-01-01

    The pathogenicity of four native strains of Bacillus thuringiensis against Rhipicephalus (Boophilus) microplus (Canestrine) (Acari: Ixodidae) was evaluated. A R. microplus strain that is resistant to organophosphates, pyrethroids, and amidines, was used in this study. Adult R. microplus females were bioassayed using the immersion test of Drummond against 60 B. thuringiensis strains. Four strains, GP123, GP138, GP130, and GP140, were found to be toxic. For the immersion test, the total protein...

  13. The global establishment of a highly-fluoroquinolone resistant Salmonella enterica serotype Kentucky ST198 strain

    Directory of Open Access Journals (Sweden)

    Simon eLe Hello

    2013-12-01

    Full Text Available While the spread of Salmonella enterica serotype Kentucky resistant to ciprofloxacin across Africa and the Middle-East has been described recently, the presence of this strain in humans, food, various animal species (livestock, pets, and wildlife and in environment is suspected in other countries of different continents. Here, we report results of an in-depth molecular epidemiological study on a global human and non-human collection of S. Kentucky (n=70.We performed XbaI-pulsed field gel electrophoresis and multilocus sequence typing, assessed mutations in the quinolone resistance-determining regions, detected β-lactam resistance mechanisms, and screened the presence of the Salmonella genomic island 1 (SGI1. In this study, we highlight the rapid and extensive worldwide dissemination of the ciprofloxacin-resistant S. Kentucky ST198-X1-SGI1 strain since the mid-2000s in an increasingly large number of contaminated sources, including the environment. This strain has accumulated an increasing number of chromosomal and plasmid resistance determinants and has been identified in the Indian subcontinent, Southeast Asia and Europe since 2010. The second substitution at position 87 in GyrA (replacing the amino acid Asp appeared helpful for epidemiological studies to track the origin of contamination.This global study provides evidence leading to the conclusion that high-level resistance to ciprofloxacin in S. Kentucky is a simple microbiological trait that facilitates the identification of the epidemic clone of interest, ST198-X1-SGI1. Taking this into account is essential in order to detect and monitor it easily and to take rapid measures in livestock to ensure control of this infection.

  14. Differential protein abundance in promastigotes of nitric oxide-sensitive and resistant Leishmania chagasi strains.

    Science.gov (United States)

    Alcolea, Pedro J; Tuñón, Gabriel I L; Alonso, Ana; García-Tabares, Francisco; Ciordia, Sergio; Mena, María C; Campos, Roseane N S; Almeida, Roque P; Larraga, Vicente

    2016-11-01

    Leishmania chagasi is the causative agent of zoonotic visceral leishmaniasis in Brazil. Domestic and stray dogs are the main reservoirs. The life cycle of the parasite involves two stages. Promastigotes are extracellular and develop within the sand fly gut. Amastigotes survive inside the harsh environment of the phagolysosome of mammalian host phagocytes, which display the nitric oxide defense mechanism. Surprisingly, we were able to isolate promastigotes that are also resistant to NO. This finding may be explained by the preadaptative hypothesis. An insight into the proteome of NO-sensitive and resistant promastigotes is presented herein. Total protein extracts were prepared from promastigote cultures of an NO-sensitive and a resistant strain at early-logarithmic, mid-logarithmic and stationary phase. A population enriched in metacyclic promastigotes was also isolated by Percoll gradient centrifugation. In vitro infectivity of both strains was compared. Differential protein abundance was analyzed by 2DE-MALDI-TOF/TOF. The most striking results were tested at the mRNA level by qRT-PCR. Three biological replicates were performed in all cases. NO-resistant L. chagasi promastigotes are more infective than NO-sensitive ones. Among the differentially abundant spots, 40 proteins could be successfully identified in the sensitive strain and 38 in resistant promastigotes. The increase of G6PD and the decrease of ARG and GPX transcripts and proteins contribute to NO resistance in L. chagasi promastigotes. These proteins may be studied as potential drug targets and/or vaccine candidates in the future. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  15. Rapid report acetamiprid resistance and cross-resistance in the diamondback moth, Plutella xylostella.

    Science.gov (United States)

    Ninsin, Kodwo D

    2004-09-01

    A 110-fold acetamiprid-resistant Plutella xylostella (L) strain was established after four selection experiments (in five generations) on a 9.5-fold resistant colony in the laboratory. The resistant strain did not show cross-resistance to chlorfluazuron or Bacillus thuringiensis subsp kurstaki Berliner, but displayed low resistance to cartap and phenthoate.

  16. Susceptibility of selected strains used for evaluation of biocidal efficiency of disinfectants and antibiotic-resistant strains to didecyldimethylammonium chloride in 2-propanol.

    Science.gov (United States)

    Chojecka, Agnieszka; Wiercińska, Olga; Röhm-Rodowald, Ewa; Kanclerski, Krzysztof; Jakimiak, Bożenna

    2015-01-01

    Didecyldimethylammonium chloride is an active substance which is part of variety of formulations used for the disinfection and antisepsis, both in the medical area as well as in the food, industrial and institutional area. Because of the widespread use of this substance and the development of bacterial resistance to quaternary ammonium compounds (QACs), the aim of this study was determination of the susceptibility of the standard strains used for the evaluation of the effectiveness of disinfectants and standard antibiotic-resistant strains to didecyldimethylammonium chloride in 2-propanol and its bactericidal activity. Susceptibility of standard strains used for the evaluation of the effectiveness of disinfectants (Staphylococcus aureus ATCC 6538-SA; Pseudomonas aeruginosa ATCC 15442-PA) and standard antibiotic-resistant strains (Staphylococcus aureus ATCC 43300-MRSA; Pseudomonas aeruginosa ATCC 47085-PAO-LAC) to CMAP was determined by minimum inhibitory concentrations (MICs) and minimum bactericidal concentration (MBCs). The bactericidal efficiency of CMAP against these strains was evaluated by using phenol coefficient (PC). Susceptibility of Gram-positive tested strains SA and MRSA to CMAP was similar (P>0,05). Significant difference in susceptibility of tested Gram-negative strains to CMAP was evaluated between PA and PAO-LAC strains (P<0,05). However,.higher resistance of PAO-LAC to CMAP was not significant when parameters such as concentration and contact time were applied in PC method. The correct determination and application of "in use" parameters (i.e. concentration, contact time, temperature and interfering substances) in disinfection process prevents the spread of resistant strains in.the environment.

  17. Determination of Soil Moisture Content using Laboratory Experimental and Field Electrical Resistivity Values

    Science.gov (United States)

    Hazreek, Z. A. M.; Rosli, S.; Fauziah, A.; Wijeyesekera, D. C.; Ashraf, M. I. M.; Faizal, T. B. M.; Kamarudin, A. F.; Rais, Y.; Dan, M. F. Md; Azhar, A. T. S.; Hafiz, Z. M.

    2018-04-01

    The efficiency of civil engineering structure require comprehensive geotechnical data obtained from site investigation. In the past, conventional site investigation was heavily related to drilling techniques thus suffer from several limitations such as time consuming, expensive and limited data collection. Consequently, this study presents determination of soil moisture content using laboratory experimental and field electrical resistivity values (ERV). Field and laboratory electrical resistivity (ER) test were performed using ABEM SAS4000 and Nilsson400 soil resistance meter. Soil sample used for resistivity test was tested for characterization test specifically on particle size distribution and moisture content test according to BS1377 (1990). Field ER data was processed using RES2DINV software while laboratory ER data was analyzed using SPSS and Excel software. Correlation of ERV and moisture content shows some medium relationship due to its r = 0.506. Moreover, coefficient of determination, R2 analyzed has demonstrate that the statistical correlation obtain was very good due to its R2 value of 0.9382. In order to determine soil moisture content based on statistical correlation (w = 110.68ρ-0.347), correction factor, C was established through laboratory and field ERV given as 19.27. Finally, this study has shown that soil basic geotechnical properties with particular reference to water content was applicably determined using integration of laboratory and field ERV data analysis thus able to compliment conventional approach due to its economic, fast and wider data coverage.

  18. Development of Antibiotic Resistance Against Ureaplasma urealyticum Strains Isolated from Urogenital Samples

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    Musa Saraçoğlu

    2018-04-01

    Full Text Available Objective: To assess any change in the antibiotic sensitivity of Ureaplasma urealyticum strains isolated from urogenital samples in the course of time. Materials and Methods: Hospital records were retrospectively examined and cases with growth of U. urealyticum in urogenital samples in the years 2008 and 2013 were identified. Furthermore, the change in the course of time was examined by taking into consideration the cases we reported in 2001. Results: Higher rates of sensitivity against tetracycline and doxycycline were observed in 60 patients with isolated U. urealyticum. Higher rates of resistance against ofloxacin and ciprofloxacin were observed. A significant difference was found in resistance against antibiotics when the records of 2008 and 2013 were compared. A statistically significant increase was found in resistance against ofloxacin and ciprofloxacin when the records of 2001 were compared with the records of 2008 and 2013 (p<0.0005. Conclusion: U. urealyticum strains demonstrated high levels of resistance to quinolones. Resistance development is increasing in the course of time. Sensitivity against tetracycline and doxycycline has continued at high rates. It would be beneficial to consider these results during empirical treatment to be applied in cases ineligible for culturing.

  19. Increasing antibiotic resistance in preservative-tolerant bacterial strains isolated from cosmetic products.

    Science.gov (United States)

    Orús, Pilar; Gomez-Perez, Laura; Leranoz, Sonia; Berlanga, Mercedes

    2015-03-01

    To ensure the microbiological quality, consumer safety and organoleptic properties of cosmetic products, manufacturers need to comply with defined standards using several preservatives and disinfectants. A drawback regarding the use of these preservatives is the possibility of generating cross-insusceptibility to other disinfectants or preservatives, as well as cross resistance to antibiotics. Therefore, the objective of this study was to understand the adaptive mechanisms of Enterobacter gergoviae, Pseudomonas putida and Burkholderia cepacia that are involved in recurrent contamination in cosmetic products containing preservatives. Diminished susceptibility to formaldehyde-donors was detected in isolates but not to other preservatives commonly used in the cosmetics industry, although increasing resistance to different antibiotics (β-lactams, quinolones, rifampicin, and tetracycline) was demonstrated in these strains when compared with the wild-type strain. The outer membrane protein modifications and efflux mechanism activities responsible for the resistance trait were evaluated. The development of antibiotic-resistant microorganisms due to the selective pressure from preservatives included in cosmetic products could be a risk for the emergence and spread of bacterial resistance in the environment. Nevertheless, the large contribution of disinfection and preservation cannot be denied in cosmetic products. Copyright© by the Spanish Society for Microbiology and Institute for Catalan Studies.

  20. Faecal shedding of antimicrobial-resistant Clostridium difficile strains by dogs.

    Science.gov (United States)

    Álvarez-Pérez, S; Blanco, J L; Peláez, T; Lanzarot, M P; Harmanus, C; Kuijper, E; García, M E

    2015-03-01

    To longitudinally assess the shedding of antimicrobial resistant Clostridium difficile strains by clinically healthy dogs raised at breeding facilities. 18 puppies from three different litters (#1, 2 and 3) were sampled weekly from parturition to day 20-55 postpartum. Faecal samples from the mothers of litters #2 and 3 were also available for analysis. Bacterial isolates were ribotyped, tested for in vitro antimicrobial susceptibility and further characterised. C. difficile was recovered from all sampled animals of litters #1 and 2, and a third of puppies from litter #3, but marked differences in C. difficile recovery were detected in different age groups (0-100%). Recovered PCR ribotypes included 056 (22 isolates), 010 (6 isolates), 078 and 213 (2 isolates each), and 009 and 020 (1 isolate each). Different ribotypes were shed by four individual animals. Regardless of their origin and ribotype, all isolates demonstrated full resistance to levofloxacin. Additionally, all but one isolate (belonging to ribotype 078) were resistant to ertapenem, and all ribotype 010 isolates displayed high-level resistance to clindamycin, clarithromycin and erythromycin. A single ribotype 078 isolate showed metronidazole heteroresistance. Healthy dogs can shed antimicrobial-resistant C. difficile strains. © 2014 British Small Animal Veterinary Association.

  1. Laboratory Investigation of Skid Resistance for Steel Slag Utilization as Chip Seal

    OpenAIRE

    Fitria Hidayatiningrum, Laely; Budi Suparma, Latif

    2011-01-01

    Slag as waste material of steel-making process has similar characteristics with aggregate that has been widely used in pavement construction. The use of slag as chip seal aggregate to provide skid resistance needs to be analyzed. In this laboratory study, the chip seal samples are made using steel slag and natural aggregate. The bonding materials used are asphalt and epoxy resin. Skid resistance tests for all chip seal samples and also hot rolled sheet pavement without chip seal application a...

  2. Use of an allele-specific polymerase chain reaction assay to genotype pyrethroid resistant strains of Boophilus microplus (Acari: Ixodidae).

    Science.gov (United States)

    Guerrero, F D; Davey, R B; Miller, R J

    2001-01-01

    A polymerase chain reaction-based assay was developed to detect the presence of a pyrethroid resistance-associated amino acid substitution in Boophilus microplus (Canestrini). The assay uses a simple method for the extraction of genomic DNA from individual larvae and genotypes individuals for the presence of a Phe-->Ile amino acid substitution in the S6 transmembrane segment of domain III of the para-like sodium channel, clearly distinguishing heterozygotes from homozygotes. High frequencies for this amino acid substitution were found in the Corrales and San Felipe strains, which have target site insensitivity mechanisms for pyrethroid resistance. The Caporal resistant strain contained lower yet substantial numbers of amino acid-substituted alleles. Low amino acid substitution frequencies were found in the susceptible reference Gonzales strain and the Coatzacoalcos strain, which has metabolic esterase-mediated pyrethroid resistance. The amino acid substitution was not found in six other strains that were susceptible to pyrethroids.

  3. Coupled stress-strain and electrical resistivity measurements on copper based shape memory single crystals

    Directory of Open Access Journals (Sweden)

    Gonzalez Cezar Henrique

    2004-01-01

    Full Text Available Recently, electrical resistivity (ER measurements have been done during some thermomechanical tests in copper based shape memory alloys (SMA's. In this work, single crystals of Cu-based SMA's have been studied at different temperatures to analyse the relationship between stress (s and ER changes as a function of the strain (e. A good consistency between ER change values is observed in different experiments: thermal martensitic transformation, stress induced martensitic transformation and stress induced reorientation of martensite variants. During stress induced martensitic transformation (superelastic behaviour and stress induced reorientation of martensite variants, a linear relationship is obtained between ER and strain as well as the absence of hys teresis. In conclusion, the present results show a direct evidence of martensite electrical resistivity anisotropy.

  4. Simple test of synergy between ampicillin and vancomycin for resistant strains of Enterococcus faecium.

    Science.gov (United States)

    Green, M; Barbadora, K; Wadowsky, R M

    1994-11-01

    The combination of ampicillin and vancomycin kills some but not all strains of ampicillin- and vancomycin-resistant Enterococcus faecium. We compared a simple test for synergy utilizing a commercially available microdilution susceptibility system with time-kill studies and determined acceptable breakpoints for this test for 20 strains of ampicillin- and vancomycin-resistant E. faecium. The combination of ampicillin and vancomycin was tested for synergy by time-kill, broth macrodilution, and broth microdilution procedures. Repeat testing of isolates by macro- and microdilution synergy methods yielded MICs that were within one twofold dilution of each other for both intra- and intertest comparisons. Synergy was always detected by time-kill studies when the MIC of ampicillin in the combination synergy screen was 16 micrograms/ml in the combination microdilution synergy screen. The determination of the synergy by the broth microdilution procedure appears to be simple, convenient, and accurate.

  5. Enhanced resistance to fluoroquinolones in laboratory-grown mutants & clinical isolates of Shigella due to synergism between efflux pump expression & mutations in quinolone resistance determining region

    Directory of Open Access Journals (Sweden)

    Neelam Taneja

    2015-01-01

    Full Text Available Background & objectives: There is a worldwide emergence of fluoroquinolone resistance in Shigella species. To understand the molecular mechanisms associated with fluoroquinolone resistance, naturally occurring fluoroquinolone-resistant strains and laboratory-induced spontaneous mutants of Shigella spp. were used and the relative contributions of acrAB-tolC efflux pumps, gyrase and topoisomerase target gene mutations towards fluoroquinolone resistance were determined. Methods: Eight Shigella flexneri and six S. dysenteriae clinical isolates were studied. Three consecutive mutants resistant to ciprofloxacin for S. flexneri SFM1 (≥0.25 µg/ml, SFM2 (≥4 µg/ml and SFM3 (≥32 µg/ml were selected in 15 steps from susceptible isolates by serial exposure to increasing concentrations of nalidixic acid and ciprofloxacin. Similarly, two mutants for S. dysenteriae SDM1 (≥0.25 µg/ml and SDM2 (≥4 µg/ml were selected in eight steps. After PCR amplification sequence analyses of gyrase and topoisomerase target genes were performed. Expression of efflux genes acrA, acrB, acrR and tolC was measured using real-time PCR. Results: Mutations were observed in gyrA Ser [83]→Leu, Asp [87]→Asn/Gly, Val [196]→Ala and in parC Phe [93]→Val, Ser [80]→Ile, Asp [101]→Glu and Asp [110]→Glu. Overall, acrA and acrB overexpression was associated with fluoroquinolone resistance ( p0 <0.05; while tolC and acrR expression levels did not. Interpretation & conclusions: Fluoroquinolone resistance in Shigella spp. is the end product of either a single or a combination of mutations in QRDRs and/ or efflux activity. Novel polymorphisms were observed at Val [196]→Ala in gyrA in clinical isolates and Phe [93]→Val, Asp [101]→Glu, Asp [110]→Glu and in parC in majority of laboratory-grown mutants.

  6. Endosulfan Resistance Profile of Soil Bacteria and Potential Application of Resistant Strains in Bioremediation

    OpenAIRE

    Chandini P.K.; Jaysooryan K.K; Varghese Rinoy; Sreedharan K.; Smitha K. P.

    2014-01-01

    In the present study, bacterial strains were isolated from the soils of Wayanad District, Kerala, India and the isolates were tested for their tolerance to endosulfan and potential in bioremediation technology. Pesticide contamination in the soils, soil physico-chemical characteristics and socio-economic impacts of pesticide application were also analyzed. 28 pesticide compounds in the soil samples were analyzed and the results revealed that there was no pesticide residues in the soils. As pe...

  7. Functional analysis of a novel hydrogen peroxide resistance gene in Lactobacillus casei strain Shirota.

    Science.gov (United States)

    Serata, Masaki; Kiwaki, Mayumi; Iino, Tohru

    2016-11-01

    Lactic acid bacteria have a variety of mechanisms for tolerance to oxygen and reactive oxygen species, and these mechanisms differ among species. Lactobacillus casei strain Shirota grows well under aerobic conditions, indicating that the various systems involved in oxidative stress resistance function in this strain. To elucidate the mechanism of oxidative stress resistance in L. casei strain Shirota, we examined the transcriptome response to oxygen or hydrogen peroxide exposure. We then focused on an uncharacterized gene that was found to be up-regulated by both oxygen and hydrogen peroxide stress; we named the gene hprA1 (hydrogen peroxide resistance gene). This gene is widely distributed among lactobacilli. We investigated the involvement of this gene in oxidative stress resistance, as well as the mechanism of tolerance to hydrogen peroxide. Growth of L. casei MS105, an hprA1-disrupted mutant, was not affected by oxygen stress, whereas the survival rate of MS105 after hydrogen peroxide treatment was markedly reduced compared to that of the wild-type. However, the activity of MS105 in eliminating hydrogen peroxide was similar to that of the wild-type. We cloned hprA1 from L. caseiShirota and purified recombinant HprA1 protein from Escherichia coli. We demonstrated that the recombinant HprA1 protein bound to iron and prevented the formation of a hydroxyl radical in vitro. Thus, HprA1 protein probably contributes to hydrogen peroxide tolerance in L. casei strain Shirota by binding to iron in the cells and preventing the formation of a hydroxyl radical.

  8. Extended-spectrum cephalosporin- resistant Salmonella enterica serovar heidelberg strains, the Netherlands

    NARCIS (Netherlands)

    Liakopoulos, Apostolos; Geurts, Yvon; Dierikx, Cindy M.; Brouwer, Mike; Kant, Arie; Wit, Ben; Heymans, Raymond; Pelt, Van Wilfrid; Mevius, Dik J.

    2016-01-01

    Extended-spectrum cephalosporin-resistant Salmonella enterica serovar Heidelberg strains (JF6X01.0022/XbaI.0251, JF6X01.0326/XbaI.1966, JF6X01.0258/XbaI.1968, and JF6X01.0045/XbaI.1970) have been identified in the United States with pulsed-field gel electrophoresis. Our examination of isolates

  9. Role of NADPH-insensitive nitroreductase gene to metronidazole resistance of Helicobacter pylori strains

    Directory of Open Access Journals (Sweden)

    M Kargar

    2010-06-01

    Full Text Available Background and the purpose of the study: Current anti-H. pylori therapies are based on the use of two antibiotics with a proton pump inhibitor and/or a bismuth component. Metronidazole is a key component of such combination therapies in Iran. The aim of this study was to determine the role of rdxA gene in resistant strains of H. pylori isolated from Shahrekord Hajar hospital to metronidazole. Methods: This study was a cross-sectional method, which was carried out on 263 patients who referred to endoscopy department of Hajar hospital, in 2007. Biopsy samples were cultured on selective Brucella agar containing 10% blood and incubated under microerophilic condition at 370C for 3 - 7 days. Suspected colonies were tested by Gram staining, urease, oxidase and catalase activities. Organisms were confirmed to be H. pylori on the basis of the presence of ureC(glmM gene by PCR .Specific primers were used for detection of rdxA gene mutation . Results: Eighty and four strains of H. pylori determined by PCR method. Of the isolated strains, 49 (58.33% were resistant, 7 (8.33% were semi-sensitive to metronidazole and 200bp deletion in rdxA gene was observed in 2 strains. Conclusion: Because of the high metronidazole resistance in patients under study it was necessary to replace it by other antibiotics in therapeutic regimens. On the basis of low frequency of resistance mutation in rdxA gene, sequence analysis for identification of other mechanisms is suggested.

  10. Burn Patients Infected With Metallo-Beta-Lactamase-Producing Pseudomonas aeruginosa: Multidrug-Resistant Strains

    Science.gov (United States)

    Anvarinejad, Mojtaba; Japoni, Aziz; Rafaatpour, Noroddin; Mardaneh, Jalal; Abbasi, Pejman; Amin Shahidi, Maneli; Dehyadegari, Mohammad Ali; Alipour, Ebrahim

    2014-01-01

    Background: Metallo-beta-lactamase (MBL) producing Pseudomonas aeruginosa in the burn patients is a leading cause of morbidity and mortality and remains a serious health concern among the clinicians. Objectives: The aim of this study was to detect MBL-producing P. aeruginosa in burn patients and determine multidrug-resistant (MDR) strains, and respective resistance patterns. Patients and Methods: In this cross-sectional study, 270 strains of P. aeruginosa were isolated from the burn patients referred to Ghotbeddin Burn Hospital, Shiraz, Iran. Among them, 55 MBL-producing P. aeruginosa strains were isolated from 55 patients hospitalized in burn unit. Minimum inhibitory concentrations (MICs) and MBLs were determined by the E-test method. Results: Of the 55 burn cases, 29 (53%) were females and 26 (47%) males. Injured burn patients’ ages ranged from 16 to 87 years, with maximum number of cases in the age group of 16 to 36 years (n, 40; 72.7%). Overall, 32 cases were accidental (60%), and 22 were suicidal burns (40%). Of the 55 burn patients, 17 cases were expired (30%). All deaths were due to chemical exposures. In antibiotic susceptibility testing by E-test method, ceftazidime was the most effective one and 35 isolates (63.5%) were resistant to all the 11 tested antibiotics. Conclusions: Routine microbiological surveillance and careful in vitro testing of antibiotics prior to prescription and strict adherence to hospital antibiotic policy may help to prevent, treat, and control MDR and pandrug-resistant (PDR) P. aeruginosa strains in burn units. PMID:25147779

  11. Strain improvement of industrially important microorganisms based on resistance to toxic metabolites and abiotic stress.

    Science.gov (United States)

    Fiedurek, Jan; Trytek, Mariusz; Szczodrak, Janusz

    2017-06-01

    Improvement of the biosynthetic capabilities of industrially relevant microbes to produce desired metabolites in higher quantities is one of the important topics of modern biotechnology. In this article, different strategies of improvement of mutated microbial strains are briefly described. This is followed by the first comprehensive review of the literature on obtaining high yielding microorganisms, that is, mutants exhibiting resistance to antimetabolites, nutritional repression, and abiotic stresses as well as tolerance to solvents and toxic substrates or products. Furthermore, the efficiency of the microbial metabolites produced by improved microbial strains, advantages, and limitations, as well as future prospects for strategies of strain development are discussed. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  12. Characterization of antimicrobial resistance in Salmonella enterica strains isolated from Brazilian poultry production.

    Science.gov (United States)

    Mattiello, Samara P; Drescher, Guilherme; Barth, Valdir C; Ferreira, Carlos A S; Oliveira, Sílvia D

    2015-11-01

    Antimicrobial resistance profiles and presence of resistance determinants and integrons were evaluated in Salmonella enterica strains from Brazilian poultry. The analysis of 203 isolates showed that those from the poultry environment (88 isolates) were significantly more resistant to antimicrobials than isolates from other sources, particularly those isolated from poultry by-product meal (106 isolates). Thirty-seven isolates were resistant to at least three antimicrobial classes. Class 1 integrons were detected in 26 isolates, and the analysis of the variable region between the 5' conserved segment (CS) and 3' CS of each class 1 integron-positive isolate showed that 13 contained a typical 3' CS and 14 contained an atypical 3' CS. One Salmonella Senftenberg isolate harbored two class 1 integrons, showing both typical and atypical 3' CSs. The highest percentage of resistance was found to sulfonamides, and sul genes were detected in the majority of the resistant isolates. Aminoglycoside resistance was detected in 50 isolates, and aadA and aadB were present in 28 and 32 isolates, respectively. In addition, strA and strB were detected in 78.1 and 65.6% isolates resistant to streptomycin, respectively. Twenty-one isolates presented reduced susceptibility to β-lactams and harbored bla(TEM), bla(CMY), and/or bla(CTX-M). Forty isolates showed reduced susceptibility to tetracycline, and most presented tet genes. These results highlight the importance of the environment as a reservoir of resistant Salmonella, which may enable the persistence of resistance determinants in the poultry production chain, contributing, therefore, to the debate regarding the impacts that antimicrobial use in animal production may exert in human health.

  13. GENOTYPES OF EXTENSIVELY DRUG-RESISTANT MYCOBACTERIUM TUBERCULOSIS STRAINS: CLINICAL AND EPIDEMIOLOGICAL FEATURES OF PULMONARY TUBERCULOSIS

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    N. R. Vasilieva

    2016-01-01

    Full Text Available Here, we present clinical and epidemiological analysis of 85 Russian cases of pulmonary tuberculosis caused by an extensively drug-resistant M. tuberculosis strains. As defined by spoligotyping, M. tuberculosis strains belonged to the following genetic families: Beijing — 81.2%, which significantly exceeds the prevalence rate of this genotype (50% in M. tuberculosis population across Russia; LAM — 14.1% and Ural — 4.7%. Among patients infected with Beijing strains prevailed alcohol and tobacco abused males; the main source of infection were family and penitentiary contacts. This group of patients has been characterized by a variety of clinical forms of lung disease with the prevalence of fibro-cavernous tuberculosis and a significant proportion of patients with interrupted treatment. Regardless of the M. tuberculosis strain genotype, the extensively drug-resistant pulmonary tuberculosis is characterized by severe course leading to the chronic disease with the relapses and poor response to anti-tuberculosis treatment, requiring repeated hospitalizations and surgical treatments.

  14. Virulence Genes and Antimicrobial Resistance Profiles of Pasteurella multocida Strains Isolated from Rabbits in Brazil

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    Thais Sebastiana Porfida Ferreira

    2012-01-01

    Full Text Available Pasteurella multocida is responsible for a wide range of diseases in domestic animals. In rabbits, the agent is related to nasal discharge, pneumonia, otitis media, pyometra, orchitis, abscess, and septicemia. One hundred and forty rabbits with respiratory diseases from four rabbitries in São Paulo State, Brazil were evaluated for the detection of P. multocida in their nasal cavities. A total of twenty-nine animals were positive to P. multocida isolation, and 46 strains were selected and characterized by means of biochemical tests and PCR. P. multocida strains were tested for capsular type, virulence genes, and resistance profile. A total of 45.6% (21/46 of isolates belonged to capsular type A, and 54.34% (25/46 of the isolates were untypeable. None of the strains harboured toxA or pfhA genes. The frequency of the other twenty genes tested was variable, and the data generated was used to build a dendrogram, showing the relatedness of strains, which were clustered according to origin. Resistance revealed to be more common against sulfonamides and cotrimoxazole, followed by erythromycin, penicillin, and amoxicillin.

  15. Induced systemic resistance against Botrytis cinerea by Micromonospora strains isolated from root nodules

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    Pilar eMartínez-Hidalgo

    2015-09-01

    Full Text Available Micromonospora is a Gram positive bacterium that can be isolated from nitrogen fixing nodules from healthy leguminous plants, where they could be beneficial to the plant. Their plant growth promoting activity in legume and non-legume plants has been previously demonstrated. The present study explores the ability of Micromonospora strains to control fungal pathogens and to stimulate plant immunity. Micromonospora strains isolated from surface sterilized nodules of alfalfa showed in vitro antifungal activity against several pathogenic fungi. Moreover, root inoculation of tomato plants with these Micromonospora strains effectively reduced leaf infection by the fungal pathogen Botrytis cinerea, despite spatial separation between both microorganisms. This induced systemic resistance, confirmed in different tomato cultivars, is long lasting. Gene expression analyses evidenced that Micromonospora stimulates the plant capacity to activate defense mechanisms upon pathogen attack. The defensive response of tomato plants inoculated with Micromonospora spp. differs from that of non-inoculated plants, showing a stronger induction of jasmonate-regulated defenses when the plant is challenged with a pathogen. The hypothesis of jasmonates playing a key role in this defense priming effect was confirmed using defense-impaired tomato mutants, since the JA-deficient line def1 was unable to display a long term induced resistance upon Micromonospora spp. inoculation.In conclusion, nodule isolated Micromonospora strains should be considered excellent candidates as biocontrol agents as they combine both direct antifungal activity against plant pathogens and the ability to prime plant immunity.

  16. Antimicrobial Resistant Pattern of Escherichia Coli Strains Isolated from Pediatric Patients in Jordan

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    Mohammad Alshara

    2011-05-01

    Full Text Available The present study was conducted to investigate antimicrobial resistant pattern of Escherichia coli (E. coli strains isolated from clinical specimens of Jordanian pediatric patients during the period from January to December 2008. A total of 444 E. coli strains were isolated from clinical specimens and tested for their susceptibility to different antimicrobial drugs. Overall, high resistance rate was observed for ampicillin (84%, followed by amoxicillin-clavulanic acid (74.3%, cotrimoxazole (71%, nalidixic acid (47.3%, cephalothin (41%. Lower resistance rates were observed for amikacin (0% followed by Cefotaxime (11%, Ceftriaxone (11.7%, ciprofloxacin (14.5%, Norfloxacin (16.5%, gentamicin (17.3% cephalexin (20.9%, Ceftazidime (22.5%, cefixime (29.6%, and cefaclor (32.8%. Ampicillin, amoxicillin-clavulanic acid and cotrimoxazole were found to be ineffective at in vitro inhibition of the E. coli of pediatric origin. Amikacin was highly effective for E. coli with susceptibility rate of 100%. The majority of E. coli strains were susceptible to third generation cephalosporins and fluoroquinolones.

  17. [Surveillance of Antimicrobial Resistant Esherichia coli by Rectal Swab Method--Annual Change of Prevalence of Quinolone-resistant and ESBL Producing Strains from 2009 to 2013].

    Science.gov (United States)

    Nasu, Yoshitsugu; Sako, Shinichi; Yano, Tomofumi; Kosaka, Noriko

    2015-09-01

    Although most of commonly used antimicrobial agents had been susceptible to Esherichia coli, recently there are a lot of reports concerning about community-acquired infection caused by resistant E. coli. The aim of this study is to define the prevalence of resistant E. coli in normal flora colonization by the rectal swab method. From June 2009 to December 2013, 251 male patients (50-85 year-old, median 68) planned to transrectal prostate biopsy participated in this study. Stools stuck on the glove at the digital examination were provided for culture specimen. Identification of E. coli and determination of MIC was performed by MicroScan WalkAway40plus (Siemens). Isolated E. coli were deemed quinolone-resistant strains when their MIC of levofloxacine was 4 μg/mL or above according to the breakpoint MIC by the CLSI criteria. ESBL producing ability was determined by the double disk method used by CVA contained ESBL definition disc (Eikenkagaku). Of the 251 study patients, 224 patients had positive cultures of E. coli. Twenty-four patients had quinolone-resistant strains and 9 patients had ESBL producing strains. The prevalence of quinolone-resistant strains in 2009, 2010, 2011, 2012 and 2013 were 5.9% (2 out of 34 strains), 13.5% (5 out of 37 strains), 12.5% (4 out of 32 strains), 9.0% (6 out of 67) and 13.0% (7 out of 54 strains), respectively. The prevalence of ESBL producing strains in 2009, 2010, 2011, 2012 and 2013 were 0% (0 out of 34 strains), 5.4% (2 out of 37 strains), 3.1% (1 out of 32 strains), 3.0% (2 out of 67 strains) and 7.4% (4 out of 54 strains), respectively. In 2013, the prevalence of antimicrobial resistant E. coli, both quinolone-resistant and ESBL producing strains, were increasing. We have to pay a close attention to the increase of resistant E. coli.

  18. The larvicidal effects of black pepper (Piper nigrum L.) and piperine against insecticide resistant and susceptible strains of Anopheles malaria vector mosquitoes.

    Science.gov (United States)

    Samuel, Michael; Oliver, Shüné V; Coetzee, Maureen; Brooke, Basil D

    2016-04-26

    Insecticide resistance carries the potential to undermine the efficacy of insecticide based malaria vector control strategies. Therefore, there is an urgent need for new insecticidal compounds. Black pepper (dried fruit from the vine, Piper nigrum), used as a food additive and spice, and its principal alkaloid piperine, have previously been shown to have larvicidal properties. The aim of this study was to investigate the larvicidal effects of ground black pepper and piperine against third and fourth instar Anopheles larvae drawn from several laboratory-reared insecticide resistant and susceptible strains of Anopheles arabiensis, An. coluzzii, An. gambiae, An. quadriannulatus and An. funestus. Larvae were fed with mixtures of standard larval food and either ground black pepper or piperine in different proportions. Mortality was recorded 24 h after black pepper and 48 h after piperine were applied to the larval bowls. Black pepper and piperine mixtures caused high mortality in the An. gambiae complex strains, with black pepper proving significantly more toxic than piperine. The An. funestus strains were substantially less sensitive to black pepper and piperine which may reflect a marked difference in the feeding habits of this species compared to that of the Gambiae complex or a difference in food metabolism as a consequence of differences in breeding habitat between species. Insecticide resistant and susceptible strains by species proved equally susceptible to black pepper and piperine. It is concluded that black pepper shows potential as a larvicide for the control of certain malaria vector species.

  19. Antimicrobial resistance and resistance genes in Salmonella strains isolated from broiler chickens along the slaughtering process in China.

    Science.gov (United States)

    Zhu, Yuanting; Lai, Haimei; Zou, Likou; Yin, Sheng; Wang, Chengtao; Han, Xinfeng; Xia, Xiaolong; Hu, Kaidi; He, Li; Zhou, Kang; Chen, Shujuan; Ao, Xiaolin; Liu, Shuliang

    2017-10-16

    A total of 189 Salmonella isolates were recovered from 627 samples which were collected from cecal contents of broilers, chicken carcasses, chicken meat after cutting step and frozen broiler chicken products along the slaughtering process at a slaughterhouse in Sichuan province of China. The Salmonella isolates were subjected to antimicrobial susceptibility testing to 10 categories of antimicrobial agents using the Kirby-Bauer disk diffusion method. Those antibiotics-resistant isolates were further investigated for the occurrence of resistance genes, the presence of class 1 integron as well as the associated gene cassettes, and the mutations within the gyrA and parC genes. Consequently, the prevalence of Salmonella was 30.14% (47.96% for cecal content, 18.78% for chicken carcasses, 31.33% for cutting meat and 14.00% for frozen meat, respectively). The predominant serotypes were S. Typhimurium (15.34%) and S. Enteritidis (69.84%). High resistance rates to the following drugs were observed: nalidixic acid (99.5%), ampicillin (87.8%), tetracycline (51.9%), ciprofloxacin (48.7%), trimethoprim/sulfamethoxazole (48.1%), and spectinomycin (34.4%). Antimicrobial resistance profiling showed that 60.8% of isolates were multidrug resistant (MDR), and MDR strains increased from 44.7% to 78.6% along the slaughtering line. 94.6% (n=157) of beta-lactam-resistant isolates harbored at least one resistance gene of bla TEM or bla CTX-M . The relatively low prevalence of aminoglycoside resistance genes (aac(3)-II, aac(3)-IV, and ant(2″)-I) was found in 49 (66.2%) of antibiotic-resistant isolates. The tetracycline resistance genes (tet(A), tet(B), tet(C), and tet(G) and sulfonamide resistance genes (sul1, sul2, and sul3) were identified in 84 (85.7%) and 89 (97.8%) antibiotic-resistant isolates respectively. floR was identified in 44 (97.8%) florfenicol-resistant isolates. Class 1 integron was detected in 37.4% (n=43) of the MDR isolates. Two different gene cassettes, bla OXA-30 -aad

  20. A laboratory study of the correlation between the thermal conductivity and electrical resistivity of soil

    Science.gov (United States)

    Wang, Jie; Zhang, Xiaopei; Du, Lizhi

    2017-10-01

    Thermal conductivity k (Wm- 1 K- 1) and electrical resistivity ρ (Ω·m) depend on common parameters such as grain size, dry density and saturation, allowing the finding of a relationship between both parameters. In this paper, we found a linear quantitative formula between thermal conductivity and electrical resistivity of soil. To accomplish this, we measured the thermal conductivity and electrical resistivity of 57 soil samples in the laboratory; samples included 8 reconstructed soils from the Changchun area (clay, silt, and sand) with approximately 7 different saturation levels. A linear relationship between thermal conductivity and electrical resistivity was found excluding the parameter of soil saturation, and the linear model was validated with undisturbed soils in Changchun area. To fully use this relationship (e.g., by imaging the thermal conductivity of soils with electrical resistivity tomography), further measurements with different soils are needed.

  1. Mechanisms of first-line antimicrobial resistance in multi-drug and extensively drug resistant strains of Mycobacterium tuberculosis in KwaZulu-Natal, South Africa

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    Navisha Dookie

    2016-10-01

    Full Text Available Abstract Background In South Africa, drug resistant tuberculosis is a major public health crisis in the face of the colossal HIV pandemic. Methods In an attempt to understand the distribution of drug resistance in our setting, we analysed the rpoB, katG, inhA, pncA and embB genes associated with resistance to key drugs used in the treatment of tuberculosis in clinical isolates of Mycobacterium tuberculosis in the KwaZulu-Natal province. Results Classical mutations were detected in the katG, inhA and embB genes associated with resistance to isoniazid and ethambutol. Diverse mutations were recorded in the multidrug resistant (MDR and extensively drug resistant (XDR isolates for the rpoB and pncA gene associated with resistance to rifampicin and pyrazinamide. Conclusions M.tuberculosis strains circulating in our setting display a combination of previously observed mutations, each mediating resistance to a different drug. The MDR and XDR TB isolates analysed in this study displayed classical mutations linked to INH and EMB resistance, whilst diverse mutations were linked to RIF and PZA resistance. The similarity of the XDR strains confirms reports of the clonality of the XDR epidemic. The successful dissemination of the drug resistant strains in the province underscores the need for rapid diagnostics to effectively diagnose drug resistance and guide treatment.

  2. Molecular Epidemiology and Antibiotic Resistance Profiles of Methicillin-Resistant Staphylococcus aureus Strains in a Tertiary Hospital in China

    Science.gov (United States)

    Kong, Haishen; Yu, Fei; Zhang, Weili; Li, Xuefen; Wang, Hongxia

    2017-01-01

    Analysis of the genotypic characteristics and antimicrobial susceptibility patterns of methicillin-resistant Staphylococcus aureus (MRSA) is essential for the control and treatment of diseases caused by this important pathogen. In this study, MRSA isolates obtained from a tertiary caret hospital in China were subjected to spa typing, SCCmec typing, multiple locus sequence typing (MLST), and PCR targeting of the genes encoding Panton-Valentine leukocidin (PVL). The disk diffusion method was used to test the antimicrobial susceptibility of the isolates to 10 non-beta-lactam antibiotics. Among the 120 MRSA isolates studied, 18 spa types and 15 ST types were identified. The spa t311 type was the most common (a total of 60 isolates; 50%) among the study strains, and nearly all the t311 strains belonged to ST5, which is the most common ST type that was previously reported from China among the t002 isolates. ST5-II/t311 was the major prevalent clone (55, 45.8%), which was followed by ST5-II/t002 (12, 10.0%) and ST59-IV/t437 (11, 9.2%). PVL-encoding genes were found in 6.7% of the isolates. Although the ST5-II/t311 and ST5-II/t002 clones are different spa types, they shared the same resistance profile (clindamycin, erythromycin, and ciprofloxacin). Most isolates of the ST239-III/t037 clone were resistant to clindamycin, erythromycin, ciprofloxacin, gentamicin, tetracycline, and trimethoprim/sulfamethoxazole. By contrast, the MRSA isolates of the ST239-III/t030 clone were more resistant to rifampin, but they were susceptible to trimethoprim/sulfamethoxazole. Our data emphasize the need for ongoing epidemiologic surveillance. PMID:28553271

  3. Molecular Epidemiology and Antibiotic Resistance Profiles of Methicillin-Resistant Staphylococcus aureus Strains in a Tertiary Hospital in China

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    Haishen Kong

    2017-05-01

    Full Text Available Analysis of the genotypic characteristics and antimicrobial susceptibility patterns of methicillin-resistant Staphylococcus aureus (MRSA is essential for the control and treatment of diseases caused by this important pathogen. In this study, MRSA isolates obtained from a tertiary caret hospital in China were subjected to spa typing, SCCmec typing, multiple locus sequence typing (MLST, and PCR targeting of the genes encoding Panton-Valentine leukocidin (PVL. The disk diffusion method was used to test the antimicrobial susceptibility of the isolates to 10 non-beta-lactam antibiotics. Among the 120 MRSA isolates studied, 18 spa types and 15 ST types were identified. The spa t311 type was the most common (a total of 60 isolates; 50% among the study strains, and nearly all the t311 strains belonged to ST5, which is the most common ST type that was previously reported from China among the t002 isolates. ST5-II/t311 was the major prevalent clone (55, 45.8%, which was followed by ST5-II/t002 (12, 10.0% and ST59-IV/t437 (11, 9.2%. PVL-encoding genes were found in 6.7% of the isolates. Although the ST5-II/t311 and ST5-II/t002 clones are different spa types, they shared the same resistance profile (clindamycin, erythromycin, and ciprofloxacin. Most isolates of the ST239-III/t037 clone were resistant to clindamycin, erythromycin, ciprofloxacin, gentamicin, tetracycline, and trimethoprim/sulfamethoxazole. By contrast, the MRSA isolates of the ST239-III/t030 clone were more resistant to rifampin, but they were susceptible to trimethoprim/sulfamethoxazole. Our data emphasize the need for ongoing epidemiologic surveillance.

  4. Application of laboratory fungal resistance tests to solid wood and wood-plastic composite

    Science.gov (United States)

    Craig Merrill Clemons; Rebecca E. Ibach

    2003-01-01

    The fungal resistance of high density polyethylene filled with 50% wood flour was investigated using laboratory soil block tests. Modifications to standard test methods were made to increase initial moisture content, increase exposure surface area, and track moisture content, mechanical properties, and weight loss over the exposure period. Mechanical properties...

  5. Effects of processing method and moisture history on laboratory fungal resistance of wood-HDPE composites.

    Science.gov (United States)

    Craig M. Clemons; Rebecca E. Ibach

    2004-01-01

    The purpose of this study was to clarify the effects of composite processing and moisture sorption on laboratory fungal resistance of wood-plastic composites. A 2-week water soaking or cyclic boiling-drying procedure was used to infuse moisture into composites made from high-density polyethylene filled with 50 percent wood flour and processed by extrusion, compression...

  6. Co-utilization of L-arabinose and D-xylose by laboratory and industrial Saccharomyces cerevisiae strains

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    Boles Eckhard

    2006-04-01

    Full Text Available Abstract Background Fermentation of lignocellulosic biomass is an attractive alternative for the production of bioethanol. Traditionally, the yeast Saccharomyces cerevisiae is used in industrial ethanol fermentations. However, S. cerevisiae is naturally not able to ferment the pentose sugars D-xylose and L-arabinose, which are present in high amounts in lignocellulosic raw materials. Results We describe the engineering of laboratory and industrial S. cerevisiae strains to co-ferment the pentose sugars D-xylose and L-arabinose. Introduction of a fungal xylose and a bacterial arabinose pathway resulted in strains able to grow on both pentose sugars. Introduction of a xylose pathway into an arabinose-fermenting laboratory strain resulted in nearly complete conversion of arabinose into arabitol due to the L-arabinose reductase activity of the xylose reductase. The industrial strain displayed lower arabitol yield and increased ethanol yield from xylose and arabinose. Conclusion Our work demonstrates simultaneous co-utilization of xylose and arabinose in recombinant strains of S. cerevisiae. In addition, the co-utilization of arabinose together with xylose significantly reduced formation of the by-product xylitol, which contributed to improved ethanol production.

  7. Mating of 2 Laboratory Saccharomyces cerevisiae Strains Resulted in Enhanced Production of 2-Phenylethanol by Biotransformation of L-Phenylalanine.

    Science.gov (United States)

    Mierzejewska, Jolanta; Tymoszewska, Aleksandra; Chreptowicz, Karolina; Krol, Kamil

    2017-01-01

    2-Phenylethanol (2-PE) is an aromatic alcohol with a rosy scent which is widely used in the food, fragrance, and cosmetic industries. Promising sources of natural 2-PE are microorganisms, especially yeasts, which can produce 2-PE by biosynthesis and biotransformation. Thus, the first challenging goal in the development of biotechnological production of 2-PE is searching for highly productive yeast strains. In the present work, 5 laboratory Saccharomyces cerevisiae strains were tested for the production of 2-PE. Thereafter, 2 of them were hybridized by a mating procedure and, as a result, a new diploid, S. cerevisiae AM1-d, was selected. Within the 72-h batch culture in a medium containing 5 g/L of L-phenylalanine, AM1-d produced 3.83 g/L of 2-PE in a shaking flask. In this way, we managed to select the diploid S. cerevisiae AM1-d strain, showing a 3- and 5-fold increase in 2-PE production in comparison to parental strains. Remarkably, the enhanced production of 2-PE by the hybrid of 2 yeast laboratory strains is demonstrated here for the first time. © 2017 S. Karger AG, Basel.

  8. In vitro inhibitory effects of farnesol and interactions between farnesol and antifungals against biofilms of Candida albicans resistant strains.

    Science.gov (United States)

    Xia, Jinping; Qian, Fang; Xu, Wenqian; Zhang, Zhenzhen; Wei, Xin

    2017-04-01

    Antifungal resistance is a serious problem in clinical infections. Farnesol, which is a potential antifungal agent against biofilms formed by Candida albicans resistant strains (a fluconazole-resistant isolate derived from SC5314 and two clinical Candida resistant isolates), was investigated in this study. The inhibitory effects of farnesol on biofilms were examined by XTT assay. The morphological changes and biofilm thicknesses were analyzed by scanning electron microscopy and confocal laser scanning microscopy, respectively. Additionally, the checkerboard microdilution method was used to investigate the interactions between farnesol and antifungals (fluconazole, amphotericin B, caspofungin, itraconazole, terbinafine and 5-flurocytosine) against biofilms. The results showed decreased SMICs of farnesol and thinner biofilms in the farnesol-treated groups, indicating that farnesol inhibited the development of biofilms formed by the resistant strain. Furthermore, there were synergistic effects between farnesol and fluconazole/5-flurocytosine, while there were antagonistic effects between farnesol and terbinafine/itraconazole, respectively, on the biofilms formed by the resistant strains.

  9. Methicillin resistance in Staphylococcus aureus strains isolated from food and wild animal carcasses in Italy.

    Science.gov (United States)

    Traversa, A; Gariano, G R; Gallina, S; Bianchi, D M; Orusa, R; Domenis, L; Cavallerio, P; Fossati, L; Serra, R; Decastelli, L

    2015-12-01

    Following the detection of methicillin-resistant Staphylococcus aureus (MRSA) ST398 in food-producing animals, both livestock and wildlife, and derived products, are considered potential sources of MRSA in humans. There is a paucity of data on MRSA in foods in Italy, and the data regarding wild animals are particularly scarce. A total of 2162 food samples collected during official monitoring activities in 2008 were analyzed for the detection of S. aureus. Also, samples from 1365 wild animals collected by the National Reference Center for Wild Animal Diseases in 2003-2009 were subjected to anatomopathological examination. S. aureus isolates were processed for phenotypic and molecular methicillin resistance determinations. S. aureus was found in 2.0% of wild animal carcasses and in 3.2% of wild boar lymph nodes: none showed methicillin resistance. The prevalence of S. aureus in food was 17.1%. Two MRSA strains, both from bulk tank milk (prevalence 0.77%) were isolated: the strains were resistant to tetracycline, had spa-type t899, and were negative for the Panton-Valentine leukocidin gene. The low prevalence of MRSA suggests that the risk of transmission to humans via food is limited. However, attention should be paid to the cattle food chain, which may be a potential route of transmission of LA-MRSA. Copyright © 2015 Elsevier Ltd. All rights reserved.

  10. Genome sequencing and annotation of a Campylobacter coli strain isolated from milk with multidrug resistance

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    Kun C. Liu

    2016-06-01

    Full Text Available As the most prevalent bacterial cause of human gastroenteritis, food-borne Campylobacter infections pose a serious threat to public health. Whole Genome Sequencing (WGS is a tool providing quick and inexpensive approaches for analysis of food-borne pathogen epidemics. Here we report the WGS and annotation of a Campylobacter coli strain, FNW20G12, which was isolated from milk in the United States in 1997 and carries multidrug resistance. The draft genome of FNW20G12 (DDBJ/ENA/GenBank accession number LWIH00000000 contains 1, 855,435 bp (GC content 31.4% with 1902 annotated coding regions, 48 RNAs and resistance to aminoglycoside, beta-lactams, tetracycline, as well as fluoroquinolones. There are very few genome reports of C. coli from dairy products with multidrug resistance. Here the draft genome of FNW20G12, a C. coli strain isolated from raw milk, is presented to aid in the epidemiology study of C. coli antimicrobial resistance and role in foodborne outbreak.

  11. Uranium biomineralization by a metal resistant Pseudomonas aeruginosa strain isolated from contaminated mine waste.

    Science.gov (United States)

    Choudhary, Sangeeta; Sar, Pinaki

    2011-02-15

    Uranium biomineralization by a metal-resistant Pseudomonas aeruginosa strain isolated from uranium mine waste was characterized for its potential in bioremediation. Uranium resistance, its cellular localization and chemical nature of uranium-bacteria interaction were elucidated. Survival and uranium biomineralization from mine water were investigated using microcosm experiments. The selected bacterium showed U resistance and accumulation (maximum of 275 mg U g(-1)cell dry wt.) following incubation in 100 mg U L(-1), pH 4.0, for 6 h. Transmission electron microscopy and X-ray diffraction analyses revealed that bioaccumulated uranium was deposited within the cell envelope as needle shaped U-phosphate compounds that attain crystallinity only at pH 4.0. A synergistic involvement of deprotonated phosphate and carboxyl moieties in facilitating bioprecipitation of uranium was evident from FTIR analysis. Based on these findings we attribute the localized U sequestration by this bacterium as innocuous complex to its possible mechanism of uranium resistance. Microcosm data confirmed that the strain can remove soluble uranium (99%) and sequester it as U oxide and phosphate minerals while maintaining its viability. The study showed that indigenous bacteria from contaminated site that can survive uranium and other heavy metal toxicity and sequester soluble uranium as biominerals could play important role in uranium bioremediation. Copyright © 2010 Elsevier B.V. All rights reserved.

  12. Investigation of carbon storage regulation network (csr genes) and phenotypic differences between acid sensitive and resistant Escherichia coli O157:H7 strains

    Science.gov (United States)

    Background: Escherichia coli O157:H7 and related serotype strains have previously been shown to vary in acid resistance, however, little is known about strain specific mechanisms of acid resistance. We examined sensitive and resistant E. coli strains to determine the effects of growth in minimal and...

  13. Whole genome sequencing-based characterization of extensively drug resistant (XDR) strains of Mycobacterium tuberculosis from Pakistan

    KAUST Repository

    Hasan, Zahra

    2015-03-01

    Objectives: The global increase in drug resistance in Mycobacterium tuberculosis (MTB) strains increases the focus on improved molecular diagnostics for MTB. Extensively drug-resistant (XDR) - TB is caused by MTB strains resistant to rifampicin, isoniazid, fluoroquinolone and aminoglycoside antibiotics. Resistance to anti-tuberculous drugs has been associated with single nucleotide polymorphisms (SNPs), in particular MTB genes. However, there is regional variation between MTB lineages and the SNPs associated with resistance. Therefore, there is a need to identify common resistance conferring SNPs so that effective molecular-based diagnostic tests for MTB can be developed. This study investigated used whole genome sequencing (WGS) to characterize 37 XDR MTB isolates from Pakistan and investigated SNPs related to drug resistance. Methods: XDR-TB strains were selected. DNA was extracted from MTB strains, and samples underwent WGS with 76-base-paired end fragment sizes using Illumina paired end HiSeq2000 technology. Raw sequence data were mapped uniquely to H37Rv reference genome. The mappings allowed SNPs and small indels to be called using SAMtools/BCFtools. Results: This study found that in all XDR strains, rifampicin resistance was attributable to SNPs in the rpoB RDR region. Isoniazid resistance-associated mutations were primarily related to katG codon 315 followed by inhA S94A. Fluoroquinolone resistance was attributable to gyrA 91-94 codons in most strains, while one did not have SNPs in either gyrA or gyrB. Aminoglycoside resistance was mostly associated with SNPs in rrs, except in 6 strains. Ethambutol resistant strains had embB codon 306 mutations, but many strains did not have this present. The SNPs were compared with those present in commercial assays such as LiPA Hain MDRTBsl, and the sensitivity of the assays for these strains was evaluated. Conclusions: If common drug resistance associated with SNPs evaluated the concordance between phenotypic and

  14. Gram-positive bacterial resistant strains of interest in animal and public health

    Directory of Open Access Journals (Sweden)

    Ricardo Antonio Pilegi Sfaciotte

    2015-08-01

    Full Text Available Among multiresistant Gram-positive microorganisms, stands out methicillin-resistant Staphylococcus (MRS, an opportunistic pathogen associated with hospital acquired and community infections reported in medicine and large increase in reports of veterinary medicine. In veterinary medicine, numerous reports regarding several species of animals have been described. MRS is intrinsically resistant to all ?-lactam drugs. In veterinary medicine, numerous reports regarding several species of animals have been described, but Staphylococcus aureus with intermediate resistance and resistant to vancomycin (VISA/VRSA has not yet been reported in veterinary medicine, still need further study. Staphylococcus spp. are also related to antimicrobial resistance of macrolides, lincosamides, and streptogramin B (MLSB group, that has the same mechanism of action, although the drugs belong to different classes. In veterinary medicine, clindamycin (lincosamide class is widely used for skin infections, wounds, bone infections, pneumonia, infections of the oral cavity, and infections caused by anaerobic bacteria, besides being used for treatments of MRS infections. Enterococcus is another resistant Gram-positive microorganism, from which vancomycin-resistant enterococci (VREs are the most important strains. There are several reports of VREs in veterinary medicine due the use of a similar antimicrobial (avoparcin in livestock; therefore this group of microorganisms has now acquired great prominence since vancomycin is considered as the last resort for the treatment of MRS and Enterococcus associated with nosocomial infections in humans. The biggest problem these microorganisms and their resistance mechanisms cause is related to its huge impact on public health due to the increasing close contact between animals and humans. The objective of this review was to identify the main Gram-positive microorganisms associated with animals, describing their mechanisms of action that

  15. A piezo-resistive graphene strain sensor with a hollow cylindrical geometry

    Energy Technology Data Exchange (ETDEWEB)

    Nakamura, Atsushi, E-mail: nakamura.atsushi@ipc.shizuoka.ac.jp [Graduate School of Integrated Science and Technology, Shizuoka University, 3-5-1 Johoku, Hamamatsu, Shizuoka 432-8011 (Japan); Faculty of Engineering, Shizuoka University, 3-5-1 Johoku, Hamamatsu, Shizuoka 432-8011 (Japan); Hamanishi, Toshiki [Graduate School of Integrated Science and Technology, Shizuoka University, 3-5-1 Johoku, Hamamatsu, Shizuoka 432-8011 (Japan); Kawakami, Shotaro [Faculty of Engineering, Shizuoka University, 3-5-1 Johoku, Hamamatsu, Shizuoka 432-8011 (Japan); Takeda, Masanori [Graduate School of Integrated Science and Technology, Shizuoka University, 3-5-1 Johoku, Hamamatsu, Shizuoka 432-8011 (Japan); Faculty of Engineering, Shizuoka University, 3-5-1 Johoku, Hamamatsu, Shizuoka 432-8011 (Japan)

    2017-05-15

    Highlights: • A hollow tubing graphene fiber was synthesized from CVD-grown graphene on Ni wire. • The strain sensor showed the gauge factor 34.3–48.9 at 8% tensile strain. • The TGF sensors performed a writing finger motion assessment. - Abstract: We propose a resistance-type strain sensor consists of hollow tubing graphene fibers (TGFs) with dimethylpolysiloxane (PDMS) coating for millimeters-scale strain/bending detection applications. The TGFs were synthesized via graphene films grown on Ni wire by chemical vapor deposition (CVD). The TGFs are fundamentally folded continuous few-layered graphene films without edges maintained cylindrical tube supported by PDMS coating. Sensing properties were studied comparing with a multi-wall carbon nanotube (MWCNT)/PDMS composites (CNTCs) and the mechanism were discussed. In terms of the gauge factor, the sensor made of TGF is estimated to be in the range of 34.3–48.9 against 8% tensile strain. For a feasibility study, we demonstrate the human finger monitoring by means of bending angle detection on a finger joint.

  16. An Intrinsic Strain of Colistin-resistant Acinetobacter Isolated from a Japanese Patient.

    Science.gov (United States)

    Takizawa, Etsuko; Yamada, Koichi; Oinuma, Ken-Ichi; Sato, Kanako; Niki, Mamiko; Namikawa, Hiroki; Fujimoto, Hiroki; Asai, Kazuhisa; Kaneko, Yukihiro; Kakeya, Hiroshi

    2016-01-01

    We herein report the first domestic case of bacteremia caused by an intrinsic strain of colistin-resistant Acinetobacter. The Acinetobacter species was detected in the hemocultures in a febrile patient. The patient was a 65-year-old-man who was admitted to our hospital for laparotomic gastrostomy. The patient's antimicrobial susceptibility patterns were atypical; they were colistin resistant but not multiple drug resistant. A sequence analysis of rpoB identified the bacterium as an Acinetobacter genomic species 13BJ/14TU, which had only been previously reported in South Korea. He had never traveled to South Korea but frequently had contact with the South Korean community. We therefore demonstrated that infection with this species could occur in domestic cases.

  17. Two mutations associated with macrolide resistance in Treponema pallidum: increasing prevalence and correlation with molecular strain type in Seattle, Washington.

    Science.gov (United States)

    Grimes, Matthew; Sahi, Sharon K; Godornes, B Charmie; Tantalo, Lauren C; Roberts, Neal; Bostick, David; Marra, Christina M; Lukehart, Sheila A

    2012-12-01

    Although azithromycin promised to be a safe and effective single-dose oral treatment of early syphilis, azithromycin treatment failure has been documented and is associated with mutations in the 23S rDNA of corresponding Treponema pallidum strains. The prevalence of strains harboring these mutations varies throughout the United States and the world. We examined T. pallidum strains circulating in Seattle, Washington, from 2001 to 2010 to determine the prevalence of 2 mutations associated with macrolide resistance and to determine whether these mutations were associated with certain T. pallidum strain types. Subjects were enrolled in a separate ongoing study of cerebrospinal fluid abnormalities in patients with syphilis. T. pallidum DNA purified from blood and T. pallidum strains isolated from blood or cerebrospinal fluid were analyzed for two 23S rDNA mutations and for the molecular targets used in an enhanced molecular stain typing system. Nine molecular strain types of T. pallidum were identified in Seattle from 2001 to 2010. Both macrolide resistance mutations were identified in Seattle strains, and the prevalence of resistant T. pallidum exceeded 80% in 2005 and increased through 2010. Resistance mutations were associated with discrete molecular strain types of T. pallidum. Macrolide-resistant T. pallidum strains are highly prevalent in Seattle, and each mutation is associated with discrete strain types. Macrolides should not be considered for treatment of syphilis in regions where prevalence of the mutations is high. Combining the resistance mutations with molecular strain typing permits a finer analysis of the epidemiology of syphilis in a community.

  18. Resistance pattern of Helicobacter pylori strains to clarithromycin, metronidazole, and amoxicillin in Isfahan, Iran

    Directory of Open Access Journals (Sweden)

    Farzad Khademi

    2013-01-01

    Full Text Available Background: Helicobacter pylori (H. pylori resistance to antibiotics has become a global problem and is an important factor in determining the outcome of treatment of infected patients. The purpose of this study was to determine the H. pylori resistance to clarithromycin, metronidazole, and amoxicillin in gastrointestinal disorders patients. Materials and Methods: In this study, a total of 260 gastric antrum biopsy specimens were collected from patients with gastrointestinal disorders who referred to Endoscopy Section of the Isfahan Hospitals. The E-test and Modified Disk Diffusion Method (MDDM were used to verify the prevalence of antibiotic resistance in 78 H. pylori isolates to the clarithromycin, metronidazole, and amoxicillin. Results: H. pylori resistance to clarithromycin, metronidazole, and amoxicillin were 15.3, 55.1, and 6.4%, respectively. In this studyΈ we had one multidrug resistance (MDR isolates from patient with gastritis and peptic ulcer disease. Conclusion: Information on antibiotic susceptibility profile plays an important role in empiric antibiotic treatment and management of refractive cases. According to the results obtained in this study, H. pylori resistance to clarithromycin and metronidazole was relatively high. MDR strains are emerging and will have an effect on the combination therapy.

  19. Significance of Coexisting Mutations on Determination of the Degree of Isoniazid Resistance in Mycobacterium tuberculosis Strains.

    Science.gov (United States)

    Karunaratne, Galbokka Hewage Roshanthi Eranga; Wijesundera, Sandhya Sulochana; Vidanagama, Dhammika; Adikaram, Chamila Priyangani; Perera, Jennifer

    2018-04-23

    The emergence and spread of drug-resistant tuberculosis (TB) pose a threat to TB control in Sri Lanka. Isoniazid (INH) is a key element of the first-line anti-TB treatment regimen. Resistance to INH is mainly associated with point mutations in katG, inhA, and ahpC genes. The objective of this study was to determine mutations of these three genes in INH-resistant Mycobacterium tuberculosis (MTb) strains in Sri Lanka. Complete nucleotide sequence of the three genes was amplified by polymerase chain reaction and subjected to DNA sequencing. Point mutations in the katG gene were identified in 93% isolates, of which the majority (78.6%) were at codon 315. Mutations at codons 212 and 293 of the katG gene have not been reported previously. Novel mutations were recognized in the promoter region of the inhA gene (C deletion at -34), fabG1 gene (codon 27), and ahpC gene (codon 39). Single S315T mutation in the katG gene led to a high level of resistance, while a low level of resistance with high frequency (41%) was observed when katG codon 315 coexisted with the mutation at codon 463. Since most of the observed mutations of all three genes coexisted with the katG315 mutation, screening of katG315 mutations will be a useful marker for molecular detection of INH resistance of MTb in Sri Lanka.

  20. Thermotolerant Yeast Strains Adapted by Laboratory Evolution Show Trade-Off at Ancestral Temperatures and Preadaptation to Other Stresses

    DEFF Research Database (Denmark)

    Caspeta, Luis; Nielsen, Jens

    2015-01-01

    adaptive laboratory evolution, we previously isolated seven Saccharomyces cerevisiae strains with improved growth at 40°C. Here, we show that genetic adaptations to high temperature caused a growth trade-off at ancestral temperatures, reduced cellular functions, and improved tolerance of other stresses...... in the ancestral strain. The latter is an advantageous attribute for acquiring thermotolerance and correlates with the reduction of yeast functions associated with loss of respiration capacity. This trait caused glycerol overproduction that was associated with the growth trade-off at ancestral temperatures...

  1. Baseline resistance and cross-resistance among fluoroquinolones in multidrug-resistant Mycobacterium tuberculosis isolates at a national reference laboratory in India.

    Science.gov (United States)

    Mamatha, H G; Shanthi, V

    2017-09-05

    Pre-existing fluoroquinolone (FQ) resistance in multidrug-resistant tuberculosis (MDR TB) patients is a major threat in treating MDR-TB. This study was conducted to assess the percentage of FQ resistance among MDR-TB patients and to determine whether there is complete cross-resistance between FQs [ofloxacin (OFX), levofloxacin (LVX) and moxifloxacin (MXF)] used as second-line drugs in MDR-TB treatment. Among 879 MDR-TB suspects tested, 68 were confirmed to be MDR-TB and rifampicin (RIF) monoresistant. Suspects were further analysed for FQ resistance by drug susceptibility testing (DST) using Mycobacterium Growth Indicator Tube (MGIT). Minimum inhibitory concentrations (MIC) were determined for OFX, LVX and MXF. Of 879 MDR-TB suspects, RIF resistance was observed in 70 patients (8.0%), among which pre-existing FQ resistance was detected in 32%. Moreover, 88% of isolates exhibited a similar DST pattern for all three FQs tested. Cross-resistance among FQs was not complete in eight isolates; the MIC of MXF was found to be much lower than the MICs of OFX and LVX. A huge proportion of MDR-TB strains (32%) exhibiting OFX resistance prior to treatment with second-line anti-TB drugs raises major concern. Detection of baseline drug resistance in TB patients helps in reducing the transmission of drug-resistant TB. The OFX MIC was higher than its critical concentration, indicating the prevalence of baseline resistance to FQs owing to irrational use of these drugs. Copyright © 2017 International Society for Chemotherapy of Infection and Cancer. Published by Elsevier Ltd. All rights reserved.

  2. Virulence factors and antimicrobial resistance in Escherichia coli strains isolated from hen egg shells.

    Science.gov (United States)

    Grande Burgos, María José; Fernández Márquez, Maria Luisa; Pérez Pulido, Rubén; Gálvez, Antonio; Lucas López, Rosario

    2016-12-05

    Eggs may contain extraintestinal pathogenic (ExPEC) and diarrheogenic (DEC) Escherichia coli which in addition may carry antibiotic resistance. The wide use of biocides and disinfectants in the food industry may induce biocide tolerance in bacteria. The aim of the present study was to evaluate biocide tolerance and antibiotic resistance in E. coli from hen egg shells. A total of 27 isolates obtained from a screening of 180 eggs were studied. Seven isolates carried both eae and bfpA genes of typical enteropathogenic E. coli (EPEC) strains, while 14 isolates only carried eae associated with atypical EPEC strains. Shiga toxin genes stx and stx2 were detected in four isolates. Heat-stable and heat-labile enterotoxin genes as well as aggR were also detected. Several isolates had minimum inhibitory concentrations (MICs) that were higher than the wild-type for the biocide hexadecylpyridinium chloride (HDP, 18.52%) or the commercial disinfectant P3 oxonia (OX, 14.81%). Antibiotic resistance was detected for ampicillin (37.03%), streptomycin (37.03%), tetracycline (37.03%), chloramphenicol (11.11%), nalidixic acid (18.51%) and trimethoprim-sulfamethoxazole (14.81%). Eight isolates (29.63%) were biocide tolerant and antibiotic resistant. Efflux pump genes detected included acrB (96.29%), mdfA (85.18%) and oxqA (37.03%), in addition to quaternary ammonium compound (QAC) resistance genes qacA/B (11.11%) and qacE (7.40%). Antibiotic resistance genes detected included bla CTX-M-2 (22.22%), bla TEM (3.70%), bla PSE (3.70%), tet(A) (29.63%), tet(B) (29.63%), tet(C) (7.40%), tet(E) (11.11%), aac(6')-Ib (3.70%), sul1 (14.81%), dfrA12 (3.70%) and dfrA15 (3.70%). Most isolates (96.30%) carried more than one genetic determinant of resistance. The most frequent combinations were efflux pump components acrB and mdfA with tetracycline resistance genes (33.33% of isolates). Isolates carrying QAC resistance genes also carried between 4 and 8 of the additional antimicrobial resistance genes

  3. ANTIMICROBIAL DRUG RESISTANCE IN STRAINS OF Escherichia coli ISOLATED FROM FOOD SOURCES

    Directory of Open Access Journals (Sweden)

    Mohammed Uddin Rasheed

    2014-07-01

    Full Text Available A variety of foods and environmental sources harbor bacteria that are resistant to one or more antimicrobial drugs used in medicine and agriculture. Antibiotic resistance in Escherichia coli is of particular concern because it is the most common Gram-negative pathogen in humans. Hence this study was conducted to determine the antibiotic sensitivity pattern of E. coli isolated from different types of food items collected randomly from twelve localities of Hyderabad, India. A total of 150 samples comprising; vegetable salad, raw egg-surface, raw chicken, unpasteurized milk, and raw meat were processed microbiologically to isolate E. coli and to study their antibiotic susceptibility pattern by the Kirby-Bauer method. The highest percentages of drug resistance in isolates of E. coli were detected from raw chicken (23.3% followed by vegetable salad (20%, raw meat (13.3%, raw egg-surface (10% and unpasteurized milk (6.7%. The overall incidence of drug resistant E. coli was 14.7%. A total of six (4% Extended Spectrum β-Lactamase (ESBL producers were detected, two each from vegetable salads and raw chicken, and one each from raw egg-surface and raw meat. Multidrug resistant strains of E. coli are a matter of concern as resistance genes are easily transferable to other strains. Pathogen cycling through food is very common and might pose a potential health risk to the consumer. Therefore, in order to avoid this, good hygienic practices are necessary in the abattoirs to prevent contamination of cattle and poultry products with intestinal content as well as forbidding the use of untreated sewage in irrigating vegetables.

  4. Chemosensitization of Trypanosoma congolense strains resistant to isometamidium chloride by tetracyclines and enrofloxacin.

    Directory of Open Access Journals (Sweden)

    Vincent Delespaux

    Full Text Available BACKGROUND: Because of the development of resistance in trypanosomes to trypanocidal drugs, the livelihood of millions of livestock keepers in sub-Saharan Africa is threatened now more than ever. The existing compounds have become virtually useless and pharmaceutical companies are not keen on investing in the development of new trypanocides. We may have found a breakthrough in the treatment of resistant trypanosomal infections, through the combination of the trypanocide isometamidium chloride (ISM with two affordable veterinary antibiotics. METHODOLOGY/PRINCIPAL FINDINGS: In a first experiment, groups of mice were inoculated with Trypanosoma congolense strains resistant to ISM and either left untreated or treated with (i tetracycline, (ii ISM or (iii the combination of the antibiotic and the trypanocide. Survival analysis showed that there was a significant effect of treatment and resistance to treatment on the survival time. The groups treated with ISM (with or without antibiotic survived significantly longer than the groups that were not treated with ISM (P<0.01. The group treated with the combination trypanocide/antibiotic survived significantly longer than the group treated with ISM (P<0.01. In a second experiment, groups of cattle were inoculated with the same resistant trypanosome strain and treated with (i ISM, (ii ISM associated with oxytetracycline or (iii ISM associated with enrofloxacine. All animals treated with ISM became parasitaemic. In the groups treated with ISM-oxytetracycline and ISM-enrofloxacine, 50% of the animals were cured. Animals from the groups treated with a combination trypanocide/antibiotic presented a significantly longer prepatent period than animals treated with ISM (p<0.001. The impact of the disease on the haematocrit was low in all ISM treated groups. Yet, it was lower in the groups treated with the combination trypanocide/antibiotic (p<0.01. CONCLUSIONS/SIGNIFICANCE: After optimization of the administration

  5. Antibiotic resistance of Vibrio cholerae O1 El Tor strains from the seventh pandemic in China, 1961-2010.

    Science.gov (United States)

    Wang, Ruibai; Lou, Jing; Liu, Jie; Zhang, Lijuan; Li, Jie; Kan, Biao

    2012-10-01

    Antibiotic resistance is observed with increasing frequency among epidemic Vibrio cholerae strains in some countries. In this study, the antibiotic resistance profiles of V. cholerae O1 El Tor strains isolated in China from 1961 to 2010 were analysed. The frequency of antibiotic resistance among the seventh pandemic El Tor isolates from China remained low, except for resistance to nalidixic acid (45.9%), tetracycline (11%) and trimethoprim/sulfamethoxazole (38.5%). All test strains in the first multiyear epidemic in the 1960s were sensitive to all test antibiotics, whereas strains from the 1990s and later showed a rapid increase in the prevalence of resistance. The class I integron was present primarily among strains isolated between 1993 and 1998, and the prevalence of the SXT element was much greater among strains isolated after 1993. This study determined the regional resistance characteristics of epidemic clones in China and serves as a warning of the rapid dissemination of resistance in the past 20 years. Copyright © 2012 Elsevier B.V. and the International Society of Chemotherapy. All rights reserved.

  6. Substitutions in Penicillin-Binding Protein 1 in Amoxicillin-Resistant Helicobacter pylori Strains Isolated from Korean Patients

    Science.gov (United States)

    Kim, Beom Jin

    2013-01-01

    Background/Aims A worldwide increase in amoxicillin resistance in Helicobacter pylori is having an adverse effect on eradication therapy. In this study, we investigated the mechanism of the amoxicillin resistance of H. pylori in terms of amino acid substitutions in penicillin-binding protein 1 (PBP1). Methods In total, 150 H. pylori strains were isolated from 144 patients with chronic gastritis, peptic ulcers, or stomach cancer. The minimum inhibitory concentrations (MICs) of the strains were determined with a serial 2-fold agar dilution method. The resistance breakpoint for amoxicillin was defined as >0.5 µg/mL. Results Nine of 150 H. pylori strains showed amoxicillin resistance (6%). The MIC values of the resistant strains ranged from 1 to 4 µg/mL. A PBP1 sequence analysis of the resistant strains revealed multiple amino acid substitutions: Val16→Ile, Val45→Ile, Ser414→Arg, Asn562→Tyr, Thr593→Ala, Gly595→Ser, and Ala599→Thr. The natural transformation of these mutated genes into amoxicillin-sensitive strains was performed in two separate pbp1 gene segments. A moderate increase in the amoxicillin MIC was observed in the segment that contained the penicillin-binding motif of the C-terminal portion, the transpeptidase domain. Conclusions pbp1 mutation affects the amoxicillin resistance of H. pylori through the transfer of the penicillin-binding motif. PMID:24312705

  7. Substitutions in penicillin-binding protein 1 in amoxicillin-resistant Helicobacter pylori strains isolated from Korean patients.

    Science.gov (United States)

    Kim, Beom Jin; Kim, Jae G

    2013-11-01

    A worldwide increase in amoxicillin resistance in Helicobacter pylori is having an adverse effect on eradication therapy. In this study, we investigated the mechanism of the amoxicillin resistance of H. pylori in terms of amino acid substitutions in penicillin-binding protein 1 (PBP1). In total, 150 H. pylori strains were isolated from 144 patients with chronic gastritis, peptic ulcers, or stomach cancer. The minimum inhibitory concentrations (MICs) of the strains were determined with a serial 2-fold agar dilution method. The resistance breakpoint for amoxicillin was defined as >0.5 µg/mL. Nine of 150 H. pylori strains showed amoxicillin resistance (6%). The MIC values of the resistant strains ranged from 1 to 4 µg/mL. A PBP1 sequence analysis of the resistant strains revealed multiple amino acid substitutions: Val16→Ile, Val45→Ile, Ser414→Arg, Asn562→Tyr, Thr593→Ala, Gly595→Ser, and Ala599→Thr. The natural transformation of these mutated genes into amoxicillin-sensitive strains was performed in two separate pbp1 gene segments. A moderate increase in the amoxicillin MIC was observed in the segment that contained the penicillin-binding motif of the C-terminal portion, the transpeptidase domain. pbp1 mutation affects the amoxicillin resistance of H. pylori through the transfer of the penicillin-binding motif.

  8. Life beyond the laboratory: Selection, cultivation and molecular identification of new robust algal strains for use in extreme environments

    Science.gov (United States)

    Kloeck, Gerd; Franziska Bleeke, M. Sc.; Corinna Kontradowitz, M. Sc.; Noke, Anja

    Microalgae are some of the world's oldest organisms, phylogenetically. Microalgae can be found virtually everywhere, adapted to almost any habitat, from oceans and fresh-water lakes to deserts, arctic regions and the interior of rocks.Because microalgae can, in principle, adapt to a wide range of environmental conditions, these organisms are of special interest in life support and space exploration. However, most current studies on microalgae are perfomend with labo-ratory strains or so calles "model organisms", which are usually do not grow well under extreme conditions. We report here the results of a screening programme for new algae strains, which grow fast at elevated temperatures, extreme pH values, high irradiance and variing osmolari-ties. About 130 samples from sites in Germany, Spain (Mainland, Balearic and Canary Islands), Italy, Portugal and New Zealand were collected. The algae were isolated and maintained in liq-uid media. From a total of 30 pure cultures growth curves were created and doubling times and growth rates were determined. most strains grew very fast, the isolate T306A hat a generation time of =0.05h-1 and a doubling time of td= 14.3h-1. Temperature sensitivity tests revealed that most algae (also most laboratory strains) did not tolerate temperatures above 40C. We identifiesd about 30 strains whose thermo tolerance was above 40C. Isolate R7 grew even at 47C. Within the framework of the molecular identification by means of 18S rDNA sequencing, 22 iso-lates could be determined phylogenetically. Chlorophytes deriving from four different families (Scenedesmaceae, Chlorellaceae, Chlorococcaceae and Chlamydomonadaceae) were identified. Beside the already molecular identified strains, more than 20 strains are available for further experiments.

  9. Reduced levels of membrane-bound alkaline phosphatase are common to lepidopteran strains resistant to Cry toxins from Bacillus thuringiensis.

    Science.gov (United States)

    Jurat-Fuentes, Juan Luis; Karumbaiah, Lohitash; Jakka, Siva Rama Krishna; Ning, Changming; Liu, Chenxi; Wu, Kongming; Jackson, Jerreme; Gould, Fred; Blanco, Carlos; Portilla, Maribel; Perera, Omaththage; Adang, Michael

    2011-03-01

    Development of insect resistance is one of the main concerns with the use of transgenic crops expressing Cry toxins from the bacterium Bacillus thuringiensis. Identification of biomarkers would assist in the development of sensitive DNA-based methods to monitor evolution of resistance to Bt toxins in natural populations. We report on the proteomic and genomic detection of reduced levels of midgut membrane-bound alkaline phosphatase (mALP) as a common feature in strains of Cry-resistant Heliothis virescens, Helicoverpa armigera and Spodoptera frugiperda when compared to susceptible larvae. Reduced levels of H. virescens mALP protein (HvmALP) were detected by two dimensional differential in-gel electrophoresis (2D-DIGE) analysis in Cry-resistant compared to susceptible larvae, further supported by alkaline phosphatase activity assays and Western blotting. Through quantitative real-time polymerase chain reaction (qRT-PCR) we demonstrate that the reduction in HvmALP protein levels in resistant larvae are the result of reduced transcript amounts. Similar reductions in ALP activity and mALP transcript levels were also detected for a Cry1Ac-resistant strain of H. armigera and field-derived strains of S. frugiperda resistant to Cry1Fa. Considering the unique resistance and cross-resistance phenotypes of the insect strains used in this work, our data suggest that reduced mALP expression should be targeted for development of effective biomarkers for resistance to Cry toxins in lepidopteran pests.

  10. Reduced levels of membrane-bound alkaline phosphatase are common to lepidopteran strains resistant to Cry toxins from Bacillus thuringiensis.

    Directory of Open Access Journals (Sweden)

    Juan Luis Jurat-Fuentes

    Full Text Available Development of insect resistance is one of the main concerns with the use of transgenic crops expressing Cry toxins from the bacterium Bacillus thuringiensis. Identification of biomarkers would assist in the development of sensitive DNA-based methods to monitor evolution of resistance to Bt toxins in natural populations. We report on the proteomic and genomic detection of reduced levels of midgut membrane-bound alkaline phosphatase (mALP as a common feature in strains of Cry-resistant Heliothis virescens, Helicoverpa armigera and Spodoptera frugiperda when compared to susceptible larvae. Reduced levels of H. virescens mALP protein (HvmALP were detected by two dimensional differential in-gel electrophoresis (2D-DIGE analysis in Cry-resistant compared to susceptible larvae, further supported by alkaline phosphatase activity assays and Western blotting. Through quantitative real-time polymerase chain reaction (qRT-PCR we demonstrate that the reduction in HvmALP protein levels in resistant larvae are the result of reduced transcript amounts. Similar reductions in ALP activity and mALP transcript levels were also detected for a Cry1Ac-resistant strain of H. armigera and field-derived strains of S. frugiperda resistant to Cry1Fa. Considering the unique resistance and cross-resistance phenotypes of the insect strains used in this work, our data suggest that reduced mALP expression should be targeted for development of effective biomarkers for resistance to Cry toxins in lepidopteran pests.

  11. The rph2 gene is responsible for high level resistance to phosphine in independent field strains of Rhyzopertha dominica.

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    Yosep S Mau

    Full Text Available The lesser grain borer Rhyzopertha dominica (F. is one of the most destructive insect pests of stored grain. This pest has been controlled successfully by fumigation with phosphine for the last several decades, though strong resistance to phosphine in many countries has raised concern about the long term usefulness of this control method. Previous genetic analysis of strongly resistant (SR R. dominica from three widely geographically dispersed regions of Australia, Queensland (SR(QLD, New South Wales (SR(NSW and South Australia (SR(SA, revealed a resistance allele in the rph1 gene in all three strains. The present study confirms that the rph1 gene contributes to resistance in a fourth strongly resistant strain, SR2(QLD, also from Queensland. The previously described rph2 gene, which interacts synergistically with rph1 gene, confers strong resistance on SR(QLD and SR(NSW. We now provide strong circumstantial evidence that weak alleles of rph2, together with rph1, contribute to the strong resistance phenotypes of SR(SA and SR2(QLD. To test the notion that rph1 and rph2 are solely responsible for the strong resistance phenotype of all resistant R. dominica, we created a strain derived by hybridising the four strongly resistant lines. Following repeated selection for survival at extreme rates of phosphine exposure, we found only slightly enhanced resistance. This suggests that a single sequence of genetic changes was responsible for the development of resistance in these insects.

  12. Longitudinal genotyping of Candida dubliniensis isolates reveals strain maintenance, microevolution, and the emergence of itraconazole resistance.

    LENUS (Irish Health Repository)

    Fleischhacker, M

    2010-05-01

    We investigated the population structure of 208 Candida dubliniensis isolates obtained from 29 patients (25 human immunodeficiency virus [HIV] positive and 4 HIV negative) as part of a longitudinal study. The isolates were identified as C. dubliniensis by arbitrarily primed PCR (AP-PCR) and then genotyped using the Cd25 probe specific for C. dubliniensis. The majority of the isolates (55 of 58) were unique to individual patients, and more than one genotype was recovered from 15 of 29 patients. A total of 21 HIV-positive patients were sampled on more than one occasion (2 to 36 times). Sequential isolates recovered from these patients were all closely related, as demonstrated by hybridization with Cd25 and genotyping by PCR. Six patients were colonized by the same genotype of C. dubliniensis on repeated sampling, while strains exhibiting altered genotypes were recovered from 15 of 21 patients. The majority of these isolates demonstrated minor genetic alterations, i.e., microevolution, while one patient acquired an unrelated strain. The C. dubliniensis strains could not be separated into genetically distinct groups based on patient viral load, CD4 cell count, or oropharyngeal candidosis. However, C. dubliniensis isolates obtained from HIV-positive patients were more closely related than those recovered from HIV-negative patients. Approximately 8% (16 of 194) of isolates exhibited itraconazole resistance. Cross-resistance to fluconazole was only observed in one of these patients. Two patients harboring itraconazole-resistant isolates had not received any previous azole therapy. In conclusion, longitudinal genotyping of C. dubliniensis isolates from HIV-infected patients reveals that isolates from the same patient are generally closely related and may undergo microevolution. In addition, isolates may acquire itraconazole resistance, even in the absence of prior azole therapy.

  13. Derivatives of a vancomycin-resistant Staphylococcus aureus strain isolated at Hershey Medical Center.

    Science.gov (United States)

    Bozdogan, Bülent; Ednie, Lois; Credito, Kim; Kosowska, Klaudia; Appelbaum, Peter C

    2004-12-01

    Antimicrobial susceptibilities and genetic relatedness of the vancomycin-resistant Staphylococcus aureus strain (VRSA) isolated at Hershey, Pa. (VRSA Hershey), and its vancomycin-susceptible and high-level-resistant derivatives were studied and compared to 32 methicillin-resistant S. aureus strains (MRSA) isolated from patients and medical staff in contact with the VRSA patient. Derivatives of VRSA were obtained by subculturing six VRSA colonies from the original culture with or without vancomycin. Ten days of drug-free subculture caused the loss of vanA in two vancomycin-susceptible derivatives for which vancomycin MICs were 1 to 4 microg/ml. Multistep selection of three VRSA clones with vancomycin for 10 days increased vancomycin MICs from 32 to 1,024 to 2,048 microg/ml. MICs of teicoplanin, dalbavancin, and oritavancin were also increased from 4, 0.5, and 0.12 to 64, 1, and 32 microg/ml, respectively. Pulsed-field gel electrophoresis (PFGE) and multilocus sequence typing analysis indicated that VRSA Hershey was the vanA-acquired variety of a common MRSA clone in our hospital with sequence type 5 (ST5). Three of five vancomycin-intermediate S. aureus strains tested from geographically different areas were also ST5, and the Michigan VRSA was ST371, a one-allele variant of ST5. Derivatives of VRSA Hershey had differences in PFGE profiles and the size of SmaI fragment that carries the vanA gene cluster, indicating instability of this cluster in VRSA Hershey. However induction with vancomycin increased glycopeptide MICs and stabilized the resistance.

  14. Emergence of Multi-drug Resistant ESBL Producing Strains among Enterobacteriaceae Members Isolated from Patients Blood Samples in South of Iran.

    Directory of Open Access Journals (Sweden)

    Jalal Mardaneh

    2015-11-01

    Full Text Available Background: Extended-spectrum beta-lactamases (ESBLs have emerged as important mechanism of resistance among enterobacteriaceae family. These ESBL positive strains are major problem in hospitalized patients. The goal of this study was the survey emergence of multi-drug resistant ESBL producing strains among enterobacteriaceae members isolated from patients blood samples using BACTEC 9240 automatic system in south of Iran. Materials & Methods: In this cross-sectional study, 4825 blood samples were collected from hospitalized patients, and positive samples were detected by BACTEC automatic system. Positive blood cultures removed from BACTEC and subculture was performed on microbiological media including blood agar, chocolate agar and MacConkey agar. The isolates were identified based on biochemical tests embedded in the API-20E system. Susceptibility testing (disc diffusion was performed according clinical and laboratory standards institute (CLSI, 2013 guidelines. Phenotypic detection of extended spectrum beta-lactamase producing isolates was performed by double disk synergy test (DDST. Results: Total 1145 (24% blood cultures were positive that among them 248 (21.5% belonged to the enterobacteriaceae family. The most common isolates in this family were Escherichia coli (46.5%, Klebsiella spp. (28%, Enterobacter spp. (13.5%. Among enterobacteriaceae family, ampicillin was most effective drug against Salmonella isolates. Escherichia coli was the most common ESBL-producing isolate (58% of isolates were ESBL positive. Respectively, polymyxin B, colistin, imipenem were the most effective drugs against ESBL-positive Klebsiella strains. The ESBL-positive Enterobacter strains showed lowest resistance to imipenem (7.7%. All ESBL positive Serratia isolates were sensitive to chloramphenicol, co-trimoxazole and imipenem. Conclusion: Results showed unfortunately betalactam antibiotics are not effective against more than 40% of bacteremia caused by Escherichia

  15. Increased prevalence of carbapenem resistant Enterobacteriaceae in hospital setting due to cross-species transmission of the bla NDM-1 element and clonal spread of progenitor resistant strains.

    Science.gov (United States)

    Wang, Xuan; Chen, Gongxiang; Wu, Xiaoyan; Wang, Liangping; Cai, Jiachang; Chan, Edward W; Chen, Sheng; Zhang, Rong

    2015-01-01

    This study investigated the transmission characteristics of carbapenem-resistant Enterobacteriaceae (CRE) strains collected from a hospital setting in China, in which consistent emergence of CRE strains were observable during the period of May 2013 to February 2014. Among the 45 CRE isolates tested, 21 (47%) strains were found to harbor the bla NDM-1 element, and the rest of 24 CRE strains were all positive for bla KPC-2. The 21 bla NDM-1-borne strains were found to comprise multiple Enterobacteriaceae species including nine Enterobacter cloacae, three Escherichia coli, three Citrobacter freundii, two Klebsiella pneumoniae, two Klebsiella oxytoca, and two Morganella morganii strains, indicating that cross-species transmission of bla NDM-1 is a common event. Genetic analyses by PFGE and MLST showed that, with the exception of E. coli and E. cloacae, strains belonging to the same species were often genetically unrelated. In addition to bla NDM-1, several CRE strains were also found to harbor the bla KPC-2, bla VIM-1, and bla IMP-4 elements. Conjugations experiments confirmed that the majority of carbapenem resistance determinants were transferable. Taken together, our findings suggest that transmission of mobile resistance elements among members of Enterobacteriaceae and clonal spread of CRE strains may contribute synergistically to a rapid increase in the population of CRE in clinical settings, prompting a need to implement more rigorous infection control measures to arrest such vicious transmission cycle in CRE-prevalent areas.

  16. Effect of chemical compositions and heat treatment on IGSCC resistance for strain hardened low carbon austenitic stainless steels in oxygenated water

    International Nuclear Information System (INIS)

    Yonezawa, T.; Kanasaki, H.; Fujimoto, K.; Taneike, M.; Ooki, S.; Sueishi, Y.; Tezuka, H.; Takamori, K.; Suzuki, S.

    2011-01-01

    In order to develop the highly resistant alternative materials to intergranular stress corrosion cracking (IGSCC) for the non-sensitized and strain hardened low carbon austenitic stainless steel in oxygenated water, the effects of chemical compositions and heat treatment conditions on the IGSCC resistance and stacking fault energy (SFE) values were studied for 33 laboratory melted steels and commercial type 310S stainless steel. The IGSCC resistance for test materials was compared by the maximum crack length, average crack length and cracked area in fatigue pre-cracked CT specimens after SCC test in oxygenated high temperature water. SFE values for these test materials were measured by the transmission electron microscopy on the width of isolated extended dislocations under g-3g weak beam condition for thin foils taken from the test materials, in this study. From these experiments, the effects of the chromium, molybdenum, nitrogen, silicon and manganese contents on the SCC resistance for non-aged materials were not so pronounced in this study. It is strongly suggested that the SFE value is a key parameter for the IGSCC resistance of the aged or non-aged and strain hardened low carbon austenitic stainless steels. (authors)

  17. Antifungal activity of terrestrial Streptomyces rochei strain HF391 against clinical azole -resistant Aspergillus fumigatus

    Science.gov (United States)

    Hadizadeh, S; Forootanfar, H; Shahidi Bonjar, GH; Falahati Nejad, M; Karamy Robati, A; Ayatollahi Mousavi, SA; Amirporrostami, S

    2015-01-01

    Background and Purpose: Actinomycetes have been discovered as source of antifungal compounds that are currently in clinical use. Invasive aspergillosis (IA) due to Aspergillus fumigatus has been identified as individual drug-resistant Aspergillus spp. to be an emerging pathogen opportunities a global scale. This paper described the antifungal activity of one terrestrial actinomycete against the clinically isolated azole-resistant A. fumigatus. Materials and Methods: Soil samples were collected from various locations of Kerman, Iran. Thereafter, the actinomycetes were isolated using starch-casein-nitrate-agar medium and the most efficient actinomycetes (capable of inhibiting A. fumigatus) were screened using agar block method. In the next step, the selected actinomycete was cultivated in starch-casein- broth medium and the inhibitory activity of the obtained culture broth was evaluated using agar well diffusion method. Results: The selected actinomycete, identified as Streptomyces rochei strain HF391, could suppress the growth of A. fumigatus isolates which was isolated from the clinical samples of patients treated with azoles. This strain showed higher inhibition zones on agar diffusion assay which was more than 15 mm. Conclusion: The obtained results of the present study introduced Streptomyces rochei strain HF391 as terrestrial actinomycete that can inhibit the growth of clinically isolated A. fumigatus. PMID:28680984

  18. Enhanced Strain-Dependent Electrical Resistance of Polyurethane Composites with Embedded Oxidized Multiwalled Carbon Nanotube Networks

    Directory of Open Access Journals (Sweden)

    R. Benlikaya

    2013-01-01

    Full Text Available The effect of different chemical oxidation of multiwalled carbon nanotubes with H2O2, HNO3, and KMnO4 on the change of electrical resistance of polyurethane composites with embedded oxidized nanotube networks subjected to elongation and bending has been studied. The testing has shown about twenty-fold increase in the electrical resistance for the composite prepared from KMnO4 oxidized nanotubes in comparison to the composites prepared from the pristine and other oxidized nanotubes. The evaluated sensitivity of KMnO4 treated composite in terms of the gauge factor increases with strain to nearly 175 at the strain 11%. This is a substantial increase, which ranks the composite prepared from KMnO4 oxidized nanotubes among materials as strain gauges with the highest electromechanical sensitivity. The observed differences in electromechanical properties of the composites are discussed on basis of their structure which is examined by the measurements of Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, and scanning electron microscope. The possible practical use of the composites is demonstrated by monitoring of elbow joint flexion during two different physical exercises.

  19. Emergence of Mycoplasma genitalium strains showing mutations associated with macrolide and fluoroquinolone resistance in the region Dresden, Germany.

    Science.gov (United States)

    Dumke, Roger; Thürmer, Alexander; Jacobs, Enno

    2016-10-01

    Among 323 specimens from male patients with symptoms of non-gonococcal urethritis, Mycoplasma genitalium was detected in 19 samples by real-time PCR. Mutations of 23S rRNA gene associated with macrolide resistance were confirmed in 10 strains. Amino acid changes at positions 81 and 83 of ParC protein were demonstrated indicating quinolone resistance of two strains. Copyright © 2016 Elsevier Inc. All rights reserved.

  20. Microbial Enhanced Oil Recovery-Laboratory Experiments with a Strain of Clostridium tyrobutyricum

    DEFF Research Database (Denmark)

    Jimoh, Ismaila Adetunji

    and produce metabolites at salinity range of over 90g/l. Strain 90F which is the adapted strain, frozen over a long period of time when activated were also able to attach to the oil water interface when grown inside test tubes at high salinity range. This can change the interfacial or wetting properties...

  1. Direct sequencing for rapid detection of multidrug resistant Mycobacterium tuberculosis strains in Morocco.

    Science.gov (United States)

    Zakham, Fathiah; Chaoui, Imane; Echchaoui, Amina Hadbae; Chetioui, Fouad; Elmessaoudi, My Driss; Ennaji, My Mustapha; Abid, Mohammed; Mzibri, Mohammed El

    2013-01-01

    Tuberculosis (TB) is a major public health problem with high mortality and morbidity rates, especially in low-income countries. Disturbingly, the emergence of multidrug resistant (MDR) and extensively drug resistant (XDR) TB cases has worsened the situation, raising concerns of a future epidemic of virtually untreatable TB. Indeed, the rapid diagnosis of MDR TB is a critical issue for TB management. This study is an attempt to establish a rapid diagnosis of MDR TB by sequencing the target fragments of the rpoB gene which linked to resistance against rifampicin and the katG gene and inhA promoter region, which are associated with resistance to isoniazid. For this purpose, 133 sputum samples of TB patients from Morocco were enrolled in this study. One hundred samples were collected from new cases, and the remaining 33 were from previously treated patients (drug relapse or failure, chronic cases) and did not respond to anti-TB drugs after a sufficient duration of treatment. All samples were subjected to rpoB, katG and pinhA mutation analysis by polymerase chain reaction and DNA sequencing. Molecular analysis showed that seven strains were isoniazid-monoresistant and 17 were rifampicin-monoresistant. MDR TB strains were identified in nine cases (6.8%). Among them, eight were traditionally diagnosed as critical cases, comprising four chronic and four drug-relapse cases. The last strain was isolated from a new case. The most recorded mutation in the rpoB gene was the substitution TCG > TTG at codon 531 (Ser531 Leu), accounting for 46.15%. Significantly, the only mutation found in the katG gene was at codon 315 (AGC to ACC) with a Ser315Thr amino acid change. Only one sample harbored mutation in the inhA promoter region and was a point mutation at the -15p position (C > T). The polymerase chain reaction sequencing approach is an accurate and rapid method for detection of drug-resistant TB in clinical specimens, and could be of great interest in the management of TB in

  2. Ultrasonic vocalizations (USV) in the three standard laboratory mouse strains: developmental analysis.

    Science.gov (United States)

    Wiaderkiewicz, Jan; Głowacka, Marta; Grabowska, Marta; Jarosław-Jerzy, Barski

    2013-01-01

    Mice, similarly to some other rodent species, communicate with specialized sounds in the ultrasonic range called ultrasonic vocalizations (USV). Evaluation of this behavioral activity enables estimation of the social interactions in animal models of autistic spectrum disorders (ASD). Because transgenic mouse models are generated, in most cases, on the mixed 129SV/C57BL6 genetic background, we were interested if parameters that characterize USV differ between these two mouse strains. In addition, we wanted to compare these strains with the BALB/c line. In order to analyze USV, we applied the standard isolation test to newborn animals and compared standard parameters. Obtained results indicate clear differences between the 129SV and C57BL6 strains in respect to all analyzed USV parameters. Both strains behave also differently when compared with the BALB/c strain. For this reason in experiments utilizing transgenic animals, contribution of various genetic backgrounds has to be carefully considered.

  3. Effect of solar radiation on multidrug resistant E. coli strains and antibiotic mixture photodegradation in wastewater polluted stream

    Energy Technology Data Exchange (ETDEWEB)

    Rizzo, L., E-mail: l.rizzo@unisa.it [Department of Civil Engineering, University of Salerno, via Ponte don Melillo, 1-84084 Fisciano (Italy); Fiorentino, A. [Department of Civil Engineering, University of Salerno, via Ponte don Melillo, 1-84084 Fisciano (Italy); Anselmo, A. [Pluriacque, via Alento, 84060 Prignano Cilento (Italy)

    2012-06-15

    The effect of solar radiation on the inactivation of multidrug resistant Escherichia coli (MDR) strains selected from an urban wastewater treatment plant (UWWTP) effluent and the change of their resistance to a mixture of three antibiotics (evaluated in terms of minimum inhibit concentration (MIC)) in wastewater polluted stream were investigated. The solar photodegradation of the mixture of the three target antibiotics (amoxicillin (AMX), ciprofloxacin (CPX), and sulfamethoxazole (SMZ)) was also evaluated. Additionally, since UWWTP effluents are possible sources of antibiotics and antibiotic resistant bacteria, the disinfection by conventional chlorination process of the UWWTP effluent inoculated with MDR strains was investigated too. Solar radiation poorly affected the inactivation of the two selected antibiotic resistant E. coli strains (40 and 60% after 180 min irradiation). Moreover, solar radiation did not affect strain resistance to AMX (MIC > 256 {mu}g/mL) and SMZ (MIC > 1024 {mu}g/mL), but affected resistance of the lower resistance strain to CPX (MIC decreased by 33% but only after 180 min of irradiation). Chlorination of wastewater sample strongly decreased the number of the two selected antibiotic resistant E. coli strains (99.667 and 99.999%), after 60 min of contact time at 2.0 mg/L initial chlorine concentration, but the resistance of survived colonies to antibiotics was unchanged. Finally, the solar photodegradation rate of the antibiotic mixture (1 mg/L initial concentration respectively) resulted in the following order (half-life time): CPX (t{sub 1/2} = 24 min) < AMX (t{sub 1/2} = 99 min) < SMZ (t{sub 1/2} = 577 min). Accordingly, the risk of the development of resistance to SMZ in surface water is significantly higher compared to CPX and AMX. - Highlights: Black-Right-Pointing-Pointer Solar radiation did not affect E. coli strain resistance to AMX and SMZ. Black-Right-Pointing-Pointer Solar radiation affected the resistance of one E. coli strain

  4. Effect of solar radiation on multidrug resistant E. coli strains and antibiotic mixture photodegradation in wastewater polluted stream

    International Nuclear Information System (INIS)

    Rizzo, L.; Fiorentino, A.; Anselmo, A.

    2012-01-01

    The effect of solar radiation on the inactivation of multidrug resistant Escherichia coli (MDR) strains selected from an urban wastewater treatment plant (UWWTP) effluent and the change of their resistance to a mixture of three antibiotics (evaluated in terms of minimum inhibit concentration (MIC)) in wastewater polluted stream were investigated. The solar photodegradation of the mixture of the three target antibiotics (amoxicillin (AMX), ciprofloxacin (CPX), and sulfamethoxazole (SMZ)) was also evaluated. Additionally, since UWWTP effluents are possible sources of antibiotics and antibiotic resistant bacteria, the disinfection by conventional chlorination process of the UWWTP effluent inoculated with MDR strains was investigated too. Solar radiation poorly affected the inactivation of the two selected antibiotic resistant E. coli strains (40 and 60% after 180 min irradiation). Moreover, solar radiation did not affect strain resistance to AMX (MIC > 256 μg/mL) and SMZ (MIC > 1024 μg/mL), but affected resistance of the lower resistance strain to CPX (MIC decreased by 33% but only after 180 min of irradiation). Chlorination of wastewater sample strongly decreased the number of the two selected antibiotic resistant E. coli strains (99.667 and 99.999%), after 60 min of contact time at 2.0 mg/L initial chlorine concentration, but the resistance of survived colonies to antibiotics was unchanged. Finally, the solar photodegradation rate of the antibiotic mixture (1 mg/L initial concentration respectively) resulted in the following order (half-life time): CPX (t 1/2 = 24 min) 1/2 = 99 min) 1/2 = 577 min). Accordingly, the risk of the development of resistance to SMZ in surface water is significantly higher compared to CPX and AMX. - Highlights: ► Solar radiation did not affect E. coli strain resistance to AMX and SMZ. ► Solar radiation affected the resistance of one E. coli strain to CPX. ► MIC for CPX decreased by 33% after 180 min of solar irradiation.

  5. Cockroaches as a Source of High Bacterial Pathogens with Multidrug Resistant Strains in Gondar Town, Ethiopia.

    Science.gov (United States)

    Moges, Feleke; Eshetie, Setegn; Endris, Mengistu; Huruy, Kahsay; Muluye, Dagnachew; Feleke, Tigist; G/Silassie, Fisha; Ayalew, Getenet; Nagappan, Raja

    2016-01-01

    Background. Cockroaches are source of bacterial infections and this study was aimed to assess bacterial isolates and their antimicrobial profiles from cockroaches in Gondar town, Ethiopia. Methods. A total of 60 cockroaches were collected from March 1 to May 30, 2014, in Gondar town. Bacterial species were isolated from external and internal parts of cockroaches. Disk diffusion method was used to determine antibiotic susceptibility patterns. Data were entered and analyzed by using SPSS version 20; P values cockroaches, respectively. Klebsiella pneumoniae 32 (17.7%), Escherichia coli 29 (16%), and Citrobacter spp. 27 (15%) were the predominant isolates. High resistance rate was observed to cotrimoxazole, 60 (33.1%), and least resistance rate was noted to ciprofloxacin, 2 (1.1%). Additionally, 116 (64.1%) of the isolates were MDR strains; Salmonella spp. were the leading MDR isolates (100%) followed by Enterobacter (90.5%) and Shigella spp. (76.9%). Conclusion. Cockroaches are the potential source of bacteria pathogens with multidrug resistant strains and hence effective preventive and control measures are required to minimize cockroach related infections.

  6. Draft Genome Sequence of Methicillin-Resistant Staphylococcus aureus Strain LC33 Isolated from Human Breast Milk

    OpenAIRE

    de Almeida, J?ssica B.; de Carvalho, Suzi P.; de Freitas, Leandro M.; Guimar?es, Ana Marcia S.; do Nascimento, Na?la C.; dos Santos, Andrea P.; Messick, Joanne B.; Timenetsky, Jorge; Marques, Lucas M.

    2017-01-01

    ABSTRACT Here, we report the draft genome sequence of Staphylococcus aureus strain LC33, isolated from human breast milk in Brazil. This microorganism has been typed as ST1/t127/sccmecV. To our knowledge, this is the first draft genome sequence of a methicillin-resistant S.?aureus strain isolated from human breast milk.

  7. Draft Genome Sequence of Methicillin-Resistant Staphylococcus aureus Strain LC33 Isolated from Human Breast Milk

    Science.gov (United States)

    de Almeida, Jéssica B.; de Carvalho, Suzi P.; de Freitas, Leandro M.; Guimarães, Ana Marcia S.; do Nascimento, Naíla C.; dos Santos, Andrea P.; Messick, Joanne B.; Timenetsky, Jorge

    2017-01-01

    ABSTRACT Here, we report the draft genome sequence of Staphylococcus aureus strain LC33, isolated from human breast milk in Brazil. This microorganism has been typed as ST1/t127/sccmecV. To our knowledge, this is the first draft genome sequence of a methicillin-resistant S. aureus strain isolated from human breast milk. PMID:28408673

  8. Introduction of plasmid DNA into an ST398 livestock-associated methicillin-resistant Staphylococcus aureus strain

    Science.gov (United States)

    MRS926 is a livestock-associated methicillin-resistant Staphylococcus aureus (MRSA) strain of sequence type (ST) 398. In order to facilitate in vitro and in vivo studies of this strain, we sought to tag it with a fluorescent marker. We cloned a codon-optimized gene for TurboGFP into a shuttle vector...

  9. IncA/C plasmids harboured in serious multidrug-resistant Vibrio cholerae serogroup O139 strains in China.

    Science.gov (United States)

    Wang, Ruibai; Yu, Dong; Zhu, Lianhui; Li, Jie; Yue, Junjie; Kan, Biao

    2015-03-01

    Vibrio cholerae serogroup O139 emerged in 1992 and is one of two major serogroups to have caused cholera epidemics. After 1998, serious multidrug-resistant (MDR) O139 strains quickly became common in China, showing a multidrug resistance profile to eight antibiotics. It is a great threat to public health, and elucidation of its mechanisms of resistance will provide a helpful guide for the clinical treatment and prevention of cholera. In this study, mega-plasmids from MDR V. cholerae O139 strains were identified by pulsed-field gel electrophoresis (PFGE) without enzyme digestion. One plasmid was isolated and sequenced, belonging to the IncA/C family. Ten antibiotic resistance genes were found in the MDR regions, including a blaTEM-20 gene, and these genes endowed the host with resistance to seven antibiotics. This kind of plasmid was positive in 71.2% (198/278) of toxigenic O139 strains, and the rate of plasmid positivity was consistent with the yearly change in MDR rates of these strains. This study reveals an important role of the IncA/C family plasmid in the spread of multiple antibiotic resistance of epidemic V. cholerae serogroup O139 strains, which has recombined with plasmids from different bacterial species and transferred among V. cholerae strains. Copyright © 2014 Elsevier B.V. and the International Society of Chemotherapy. All rights reserved.

  10. [Experimental study on phenotypic conversion of clinical chloromycetin-resistant strains of E. coli to drug-sensitive strains by using EGS technique in vitro].

    Science.gov (United States)

    Gao, Mei-ying; Chen, Ru; Liu, Shou-gui; Feng, Jiang-nan

    2004-08-02

    To explore the possibility of phenotypic conversion of clinical chloromycetin (Cm)-resistant isolates of E.coli to drug-sensitive ones with external guide sequences (EGS) in vitro. Recombinant EGS plasmids directed against Cm acetyl transferase (cat) and containing kanamycin (Km) drug-resistance gene and control plasmids only containing kanamycin-resistance gene without EGS were constructed. By using CaCl(2) method, the recombinant plasmids were introduced into the clinically isolated Cm-resistant E.coli strains. Extraction of plasmids and PCR were applied to identify the EGS positive clones; The growth rate in liquid broth culture of Cm-resistant bacteria after EGS containing plasmid transformation was determined by spectrophotometer A(600). Drug sensitivity was tested in solid culture by using KB method. Transformation studies were carried out on 16 clinically isolated Cm-resistant E.coli strains with pEGFP-C1-EGS + cat1 + cat2 recombinant plasmid. Transformants were screened on LB-agar plates containing Km after transformation using EGS. In 4 tested strains of them, transformants with specific EGS plasmid showed growth inhibition when grown in liquid broth culture containing 100 approximately 200 micro g/ml of Cm. They were sensitive to Cm on LB-agar plates containing 100 approximately 200 micro g/ml of Cm in drug-sensitivity test. Extraction of plasmids showed the existence of EGS bands. PCR amplified products of EGS. The above facts indicated that the 4 strains out of the 16 clinical isolates had been converted to drug-sensitive phenotype, and Cm-resistant clinically isolated E. coli resumed sensitivity to Cm. EGS has the capability of converting the phenotype of clinical drug-resistant isolates to drug sensitivity.

  11. Treponema pallidum Strain Types and Association with Macrolide Resistance in Sydney, Australia: New TP0548 Gene Types Identified.

    Science.gov (United States)

    Read, Phillip; Tagg, Kaitlin A; Jeoffreys, Neisha; Guy, Rebecca J; Gilbert, Gwendolyn L; Donovan, Basil

    2016-08-01

    Strain typing of Treponema pallidum, using the three-target enhanced classification scheme, was performed with 191 samples obtained between 2004 and 2011 in Sydney, Australia. The most common strain type was 14d/g (92/191 samples [48%]). Two new TP0548 gene types were detected (m and n). Strain type was associated with macrolide resistance and possible acquisition outside Australia. Copyright © 2016, American Society for Microbiology. All Rights Reserved.

  12. Detection of methicillin-resistant Staphylococcus aureus strains resistant to multiple antibiotics and carrying the Panton-Valentine leukocidin genes in an Algiers hospital.

    Science.gov (United States)

    Ramdani-Bouguessa, Nadjia; Bes, Michèle; Meugnier, Hélène; Forey, Françoise; Reverdy, Marie-Elisabeth; Lina, Gerard; Vandenesch, François; Tazir, Mohamed; Etienne, Jerome

    2006-03-01

    Forty-five Panton-Valentine leukocidin (PVL)-positive, methicillin-resistant Staphylococcus aureus strains were isolated in Algeria between 2003 and 2004; 18 isolates were isolated in the community and 27 in a hospital. Five PVL-positive hospital isolates were resistant to multiple antibiotics, including ofloxacin and gentamicin for three isolates.

  13. Bovine mastitis Staphylococcus aureus: antibiotic susceptibility profile, resistance genes and molecular typing of methicillin-resistant and methicillin-sensitive strains in China.

    Science.gov (United States)

    Wang, Dengfeng; Wang, Zhicai; Yan, Zuoting; Wu, Jianyong; Ali, Tariq; Li, Jianjun; Lv, Yanli; Han, Bo

    2015-04-01

    The emergence of methicillin-resistant Staphylococcus aureus (MRSA) infection in dairy animals is of great concern for livestock and public health. The aim of present study was to detect new trends of methicillin-resistant Staphylococcus aureus (MRSA) and methicillin-sensitive Staphylococcus aureus (MSSA) towards antibiotic susceptibility, resistance genes and molecular typing by methods of disc diffusion, multiplex PCR assay and multilocus sequence typing (MLST). A total of 219 S. aureus strains were isolated from bovine mastitis cases from six provinces of China, including 34 MRSA strains. The results revealed that more than 70% isolated strains showed resistance to various antibiotics, and multiple-drugs resistance to more than five categories of antibiotics was found more common. The ermC was the most prevalent resistance gene, followed by other genes; however, ermA was the least frequently detected gene. Twenty-eight mecA-negative MRSA and six mecA-positive MRSA strains were detected, and in which three strains were ST97-MRSA-IV, others were ST965-MRSA-IV, ST6-MRSA-IV and ST9-MRSA-SCCmec-NT. The mecA-negative MRSA strains were found resistant to most of the antibiotics, and harbored aac(6')/aph(2''), aph(3')-III and tetM genes higher than MSSA strains. The resistance to most of the antibiotics was significantly higher in MRSA than in MSSA strains. The MLST profiles showed that these strains mainly belonged to CC5, CC398, CC121 and CC50 lineage, especially within ST97 and ST398, while some novel sequence types (ST2154, ST2165 and ST2166) were identified and deposited in the MLST database. This indicates that the resistance of S. aureus is becoming more complicated by changes in multi-drug resistance mechanism and appearance of mecA-negative MRSA isolates, and importantly, MRSA-IV strains in different MLST types are emerging. Copyright © 2015 Elsevier B.V. All rights reserved.

  14. Transcriptional analysis of four family 4 P450s in a Puerto Rico strain of Aedes aegypti (Diptera: Culicidae) compared with an Orlando strain and their possible functional roles in permethrin resistance

    Science.gov (United States)

    A field strain of Aedes aegypti was collected from Puerto Rico (PR) in October 2008. Based on LD50 values by topical application, the PR strain was 73-fold resistant to permethrin compared to a susceptible Orlando strain. In the presence of piperonyl butoxide (PBO), the resistance of Puerto Rico str...

  15. Increased transmission of Mycobacterium tuberculosis Beijing genotype strains associated with resistance to streptomycin: a population-based study.

    Science.gov (United States)

    Buu, Tran N; van Soolingen, Dick; Huyen, Mai N T; Lan, Nguyen T N; Quy, Hoang T; Tiemersma, Edine W; Kremer, Kristin; Borgdorff, Martien W; Cobelens, Frank G J

    2012-01-01

    Studies have shown that the Mycobacterium tuberculosis Beijing genotype is an emerging pathogen that is frequently associated with drug resistance. This suggests that drug resistant Beijing strains have a relatively high transmission fitness compared to other drug-resistant strains. We studied the relative transmission fitness of the Beijing genotype in relation to anti-tuberculosis drug resistance in a population-based study of smear-positive tuberculosis patients prospectively recruited and studied over a 4-year period in rural Vietnam. Transmission fitness was analyzed by clustering of cases on basis of three DNA typing methods. Of 2531 included patients, 2207 (87%) were eligible for analysis of whom 936 (42%) were in a DNA fingerprint cluster. The clustering rate varied by genotype with 292/786 (37%) for the Beijing genotype, 527/802 (67%) for the East-African Indian (EAI) genotype, and 117/619 (19%) for other genotypes. Clustering was associated with the EAI compared to the Beijing genotype (adjusted odds ratio (OR(adj)) 3.4: 95% CI 2.8-4.4). Patients infected with streptomycin-resistant strains were less frequently clustered than patients infected with streptomycin-susceptible strains when these were of the EAI genotype (OR(adj) 0.6, 95% CI 0.4-0.9), while this pattern was reversed for strains of the Beijing genotype (OR(adj) 1.3, 95% CI 1.0-1.8, p for difference 0.002). The strong association between Beijing and MDR-TB (OR(adj) 7.2; 95% CI 4.2-12.3) existed only if streptomycin resistance was present. Beijing genotype strains showed less overall transmissibility than EAI strains, but when comparisons were made within genotypes, Beijing strains showed increased transmission fitness when streptomycin-resistant, while the reverse was observed for EAI strains. The association between MDR-TB and Beijing genotype in this population was strongly dependent on resistance to streptomycin. Streptomycin resistance may provide Beijing strains with a fitness advantage

  16. Studying the Genetics of Resistance to CyHV-3 Disease Using Introgression from Feral to Cultured Common Carp Strains

    Science.gov (United States)

    Tadmor-Levi, Roni; Asoulin, Efrat; Hulata, Gideon; David, Lior

    2017-01-01

    Sustainability and further development of aquaculture production are constantly challenged by outbreaks of fish diseases, which are difficult to prevent or control. Developing fish strains that are genetically resistant to a disease is a cost-effective and a sustainable solution to address this challenge. To do so, heritable genetic variation in disease resistance should be identified and combined together with other desirable production traits. Aquaculture of common carp has suffered substantial losses from the infectious disease caused by the cyprinid herpes virus type 3 (CyHV-3) virus and the global spread of outbreaks indicates that many cultured strains are susceptible. In this research, CyHV-3 resistance from the feral strain “Amur Sassan” was successfully introgressed into two susceptible cultured strains up to the first backcross (BC1) generation. Variation in resistance of families from F1 and BC1 generations was significantly greater compared to that among families of any of the susceptible parental lines, a good starting point for a family selection program. Considerable additive genetic variation was found for CyHV-3 resistance. This phenotype was transferable between generations with contributions to resistance from both the resistant feral and the susceptible cultured strains. Reduced scale coverage (mirror phenotype) is desirable and common in cultured strains, but so far, cultured mirror carp strains were found to be susceptible. Here, using BC1 families ranging from susceptible to resistant, no differences in resistance levels between fully scaled and mirror full-sib groups were found, indicating that CyHV-3 resistance was successfully combined with the desirable mirror phenotype. In addition, the CyHV-3 viral load in tissues throughout the infection of susceptible and resistant fish was followed. Although resistant fish get infected, viral loads in tissues of these fish are significantly lesser than in those of susceptible fish, allowing them

  17. Phenotypic and genotypic characterization of antimicrobial resistance in enterohemorrhagic Escherichia coli and atypical enteropathogenic E. coli strains from ruminants.

    Science.gov (United States)

    Medina, Alberto; Horcajo, Pilar; Jurado, Sonia; De la Fuente, Ricardo; Ruiz-Santa-Quiteria, José A; Domínguez-Bernal, Gustavo; Orden, José A

    2011-01-01

    Two hundred and twenty-six attaching and effacing Escherichia coli (AEEC) strains (20 enterohemorrhagic E. coli and 206 atypical enteropathogenic E. coli) isolated from calves, lambs, and goat kids with diarrhea and from healthy cattle, sheep, and goats were tested for their resistance to 10 antimicrobial agents by the disc diffusion method. Resistant and intermediate strains were analyzed by polymerase chain reaction for the presence of the major resistance genes. The overall percentage of resistant strains to tetracycline, streptomycin, erythromycin, and sulfamethoxazole was very high (>65%). Moreover, a high level of resistance (approximately 30%) to ampicillin, chloramphenicol, trimethoprim, and trimethoprim-sulfamethoxazole was also detected. The AEEC strains were very susceptible (>90%) to gentamicin and colistin. Because AEEC from ruminants can cause diseases in human beings, the high frequency of antimicrobial resistance detected in the current study is a source of concern. For each antimicrobial agent, the predominant resistance genes in the resistant strains were ampicillin, bla(TEM) (97.1%); tetracycline, tetA (76.7%); gentamicin, aac(3)II (80%); streptomycin, strA/strB (76.7%) and aadA (71.7%); chloramphenicol, catI (85.1%); trimethoprim, dhfrI (76.3%); and sulfamethoxazole, sul1 (60%) and sul2 (63.3%). In the majority of cases, resistance to a given antimicrobial, except for streptomycin, was caused by a single gene. A negative association between tetA and tetB, between aac(3)II and aac(3)IV, and between dhfrI and dhfrV was observed. The present study gives baseline data on frequency and molecular basis of antimicrobial resistance in AEEC strains from ruminants.

  18. Molecular analysis of exotoxin A associated with antimicrobial resistance of Pseudomonas aeruginosa strains isolated from patients in Tehran hospitals

    Directory of Open Access Journals (Sweden)

    Nour Amirmozafari

    2014-12-01

    Full Text Available Background and Aim:  Pseudomonas aeruginosa is a unique bacteria that in order to survive in different environments by complex adaptation process can make changes in his virulence genes expression and drug resistance. The aim of this research is the investigation of existence of a logical association between toxA gene and antibiotic resistance in strains possess the gene. Materials and Methods: Antibiogram test by disk diffusion method (Kirby Bauer was performed according to CLSI protocols. In this study, the existence of toxA gene with the help of polymerase chain reaction (PCR in 102 clinical isolates from blood samples, wound, urine and trachea was examined. Chi-square test was used to investigate the relationship between exotoxin A and antibiotic resistance. Results: The 81 strains (79.4% had toxA gene. Frequency of toxA genes in isolated strains from different infections were wound (91.4%, blood (85.7%, trachea (72.7%, and urine (42.1%. Multiple resistance index in strains possess the toxA gene was calculated 75%. Chi 2 test to determine the relationship between drug resistance and gene toxA was significant (P<0.05. Conclusions: The significant chi-square test and an increase in multi-resistant strains possessing the toxA gene, can represent a considerable genetic switch between exotoxin A activity and resistance to antibiotics in the blood, urine, tracheal, wound infections Respectively, which lead to turn genes on of drug resistance regulating in bacteria. The results of this study will be verified by southern blot, analysis of the expression of toxA gene and determine the mechanism of resistance in resistant strains Methods.

  19. Effect of solar radiation on multidrug resistant E. coli strains and antibiotic mixture photodegradation in wastewater polluted stream.

    Science.gov (United States)

    Rizzo, L; Fiorentino, A; Anselmo, A

    2012-06-15

    The effect of solar radiation on the inactivation of multidrug resistant Escherichia coli (MDR) strains selected from an urban wastewater treatment plant (UWWTP) effluent and the change of their resistance to a mixture of three antibiotics (evaluated in terms of minimum inhibit concentration (MIC)) in wastewater polluted stream were investigated. The solar photodegradation of the mixture of the three target antibiotics (amoxicillin (AMX), ciprofloxacin (CPX), and sulfamethoxazole (SMZ)) was also evaluated. Additionally, since UWWTP effluents are possible sources of antibiotics and antibiotic resistant bacteria, the disinfection by conventional chlorination process of the UWWTP effluent inoculated with MDR strains was investigated too. Solar radiation poorly affected the inactivation of the two selected antibiotic resistant E. coli strains (40 and 60% after 180 min irradiation). Moreover, solar radiation did not affect strain resistance to AMX (MIC>256 μg/mL) and SMZ (MIC>1024 μg/mL), but affected resistance of the lower resistance strain to CPX (MIC decreased by 33% but only after 180 min of irradiation). Chlorination of wastewater sample strongly decreased the number of the two selected antibiotic resistant E. coli strains (99.667 and 99.999%), after 60 min of contact time at 2.0 mg/L initial chlorine concentration, but the resistance of survived colonies to antibiotics was unchanged. Finally, the solar photodegradation rate of the antibiotic mixture (1mg/L initial concentration respectively) resulted in the following order (half-life time): CPX (t(1/2)=24 min)resistance to SMZ in surface water is significantly higher compared to CPX and AMX. Copyright © 2012 Elsevier B.V. All rights reserved.

  20. Strain-induced tunable negative differential resistance in triangle graphene spirals

    Science.gov (United States)

    Tan, Jie; Zhang, Xiaoming; Liu, Wenguan; He, Xiujie; Zhao, Mingwen

    2018-05-01

    Using non-equilibrium Green’s function formalism combined with density functional theory calculations, we investigate the significant changes in electronic and transport properties of triangle graphene spirals (TGSs) in response to external strain. Tunable negative differential resistance (NDR) behavior is predicted. The NDR bias region, NDR width, and peak-to-valley ratio can be well tuned by external strain. Further analysis shows that these peculiar properties can be attributed to the dispersion widths of the p z orbitals. Moreover, the conductance of TGSs is very sensitive to the applied stress, which is promising for applications in nanosensor devices. Our findings reveal a novel approach to produce tunable electronic devices based on graphene spirals.

  1. Microalgal sensitivity varies between a diuron-resistant strain and two wild strains when exposed to diuron and irgarol, alone and in mixtures.

    Science.gov (United States)

    Dupraz, Valentin; Coquillé, Nathalie; Ménard, Dominique; Sussarellu, Rossana; Haugarreau, Larissa; Stachowski-Haberkorn, Sabine

    2016-05-01

    A wild strain of Chaetoceros calcitrans and wild and diuron-resistant strains of Tetraselmis suecica, were exposed to the PSII inhibitor herbicides diuron and irgarol, individually and in mixtures. The effects of three concentrations of diuron and irgarol and four binary mixtures were evaluated on doubling time, relative reactive oxygen species and lipid content by flow cytometry, and on photosynthetic efficiency by pulse amplitude modulated fluorescence. In both wild strains, significant effects were observed for each molecule at the highest concentration tested: at irgarol 0.5 μg L(-1), C. calcitrans was shown to be more sensitive than T. suecica (+52% and +19% in doubling time, respectively), whereas at diuron 5 μg L(-1), T. suecica was more affected (+125% in doubling time) than C. calcitrans (+21%). Overall, irgarol had a higher toxicity at a lower concentration than diuron (no effect at diuron 0.5 μg L(-1)) for both wild strains. The strongest mixture (irgarol 0.5 μg L(-1) + diuron 5 μg L(-1)) increased doubling time by 356% for T. suecica, thus showing amplified effects when the two compounds were mixed. Sequencing of the diuron-resistant strain demonstrated a single mutation in the psbA gene coding sequence. Although resistance of this strain to diuron was confirmed with no effect at the highest diuron concentration, no resistance to irgarol was shown. In addition, the mutant strain exposed to the strongest mixture showed a 3.5-fold increase in doubling time compared with irgarol alone, thereby supporting the hypothesis of a biochemical interaction between these two compounds. Copyright © 2016 Elsevier Ltd. All rights reserved.

  2. Laboratory studies on insecticide resistance, alcohol tolerance and sex ratio distortion by meiotic drive in the Mediterranean fruit fly, Ceratitis capitata (Wied.)

    International Nuclear Information System (INIS)

    Wood, R.J.

    1990-01-01

    Three approaches to developing a genetic sexing technique for the Mediterranean fruit fly (medfly), Ceratitis capitata (Wiedemann), are discussed. Laboratory studies in late third instar larvae of the medfly revealed a potential for dieldrin resistance. A programme of sib selection produced the DiR strain, more than 60x resistante to dieldrin with cross-resistance to other cyclodienes, HCH, malathion and permethrin. Adults were not resistant. Crosses showed dieldrin resistance to be monofactorial, subject to a modifying effect from the genetic background on the expression of the homozygote. The 'backcrossing with selection' technique was used to separate dieldrin and malathion resistance but, in the process, resistance to both insecticides was lost after four to eight generations. Attempts to induce male linkage of the R gene by X irradiation were unsuccessful. Further genetic studies on resistance are recommended. With a view to producing an ethanol sensitive strain homozygous for an ADH null mutation (Adh - /Adh - ), pentenol selection of late third instar larvae was carried out, combined with ethyl methane sulphonate (EMS) treatments of adults. This produced a maximum of 15x tolerance of pentenol but no associated change in ethanol tolerance. Electrophoresis (PAGE) showed that two major ADH systems were at their most active in late third instar larvae. A gene causing a male distorted sex ratio in the progeny of males carrying it was isolated after X irradiation. The expression of the gene, which appears to be an example of meiotic drive, was enhanced by reducing the ambient temperature of parent flies from 26 deg. C+-2.0 to 18 deg. C+-1.5 during days 2-5 of pupal development. Selection to increase the expression of the gene produced families with less than 20% females but sex ratio tended to revert towards normal in subsequent generations. A potential is seen for producing strains in which sex ratio can be regulated by temperature. (author). 30 refs, 5 figs, 2

  3. Inheritance and heritability of deltamethrin resistance under laboratory conditions of Triatoma infestans from Bolivia.

    Science.gov (United States)

    Gomez, Marinely Bustamante; Pessoa, Grasielle D'Avila Caldas; Rosa, Aline Cristine Luiz; Echeverria, Jorge Espinoza; Diotaiuti, Liléia Gonçalves

    2015-11-16

    Over the last few decades, pyrethroid-resistant in Triatoma infestans populations have been reported, mainly on the border between Argentina and Bolivia. Understanding the genetic basis of inheritance mode and heritability of resistance to insecticides under laboratory conditions is crucial for vector management and monitoring of insecticide resistance. Currently, few studies have been performed to characterize the inheritance mode of resistance to pyrethroids in T. infestans; for this reason, the present study aims to characterize the inheritance and heritability of deltamethrin resistance in T. infestans populations from Bolivia with different toxicological profiles. Experimental crosses were performed between a susceptible (S) colony and resistant (R) and reduced susceptibility (RS) colonies in both directions (♀ x ♂ and ♂ x ♀), and inheritance mode was determined based on degree of dominance (DO) and effective dominance (D(ML)). In addition, realized heritability (h(2)) was estimated based on a resistant colony, and select pressure was performed for two generations based on the diagnostic dose (10 ng. i. a. /nymph). The F1 progeny of the experimental crosses and the selection were tested by a standard insecticide resistance bioassay. The result for DO and D(ML) (Bolivia. The lethal doses (LD50) increase from one generation to another rapidly after selection pressure with deltamethrin. This suggests that resistance is an additive and cumulative factor, mainly in highly structured populations with limited dispersal capacity, such as T. infestans. This phenomenon was demonstrated for the first time for T. infestans in the present study. These results are very important for vector control strategies in problematic areas where high resistance ratios of T. infestans have been reported.

  4. Perfil de resistência antimicrobiana de cepas de Staphylococcus sp. isoladas de queijo tipo coalho Antimicrobial resistance profile of Staphylococcus sp. strains isolated from type "coalho" cheese

    Directory of Open Access Journals (Sweden)

    L.S. Rapini

    2004-02-01

    Full Text Available The antimicrobial resistance profile of 45 Staphylococcus strains isolated from 10 samples of Brazilian type "coalho" cheese was evaluated against eight antibiotics used either in human or in veterinarian medicine. The tested antibiotics decreasing resistance degree was: penicillin (100.0%, tetracycline (91.0%, vancomycin (75.5%, gentamicin (71.1%, oxacillin (66.7%, erythromycin (60.0%, cephalothin (48.9% and sulphazothrin (26.7%. The high frequency of Staphylococcus strains presenting resistance to the tested antibiotics, emphasizes the importance of the control of the abusive use of antibiotics by medical and veterinarian subjects.

  5. In situ Ia expression on brain cells in the rat: autoimmune encephalomyelitis-resistant strain (BN) and susceptible strain (Lewis) compared.

    Science.gov (United States)

    Matsumoto, Y; Kawai, K; Fujiwara, M

    1989-01-01

    In order to examine in situ Ia expression on brain cells of various strains of rat, experimental autoimmune encephalomyelitis (EAE) was induced in both EAE-susceptible (LEW) and EAE-resistant (BN) strains. For induction of EAE in the resistant strain, two methods were applied: one was injection of guinea-pig myelin basic protein (GPBP) in complete Freund's adjuvant into LBNF1----BN chimeras; the other was transfer of GPBP-reactive T-line cells from BN rats into syngeneic rats. LBNF----BN chimeras developed clinical EAE, whereas BN rats that received T-line cells did not. However, histological EAE was apparent in both groups. Immunohistochemical examination using two different monoclonal antibodies (OX3 and OX6) against rat Ia antigens revealed that microglia of LEW, BN and chimera rats expressed Ia antigens in the central nervous system (CNS) with EAE. On the other hand, astrocytes were negative for Ia antigens in all the strains. Furthermore, quantitative analysis was undertaken in order to compare the density of Ia-positive microglia in the BN CNS with that in the LEW CNS. It was revealed that the density of Ia-positive microglia in the vicinity of perivascular inflammatory cell aggregates was essentially the same in both strains regardless of the difference in methods of EAE induction or histological severity of the disease. Ia-positive microglia remote from inflammatory cell aggregates were somewhat fewer in rats with mild histological EAE. However, no strain difference was noted in this analysis. Therefore, we concluded that in situ Ia-inducibility on the brain cells of EAE-resistant rats is not different from that of EAE-susceptible rats. Although Ia-positive microglia in both strains may be involved in the immune responses in the CNS, it is unlikely that the difference in Ia-inducibility on brain cells would contribute to strain-specific susceptibility to EAE. Images Figure 1 Figure 2 PMID:2785488

  6. Experimental Study of Drag Resistance using a Laboratory Scale Rotary Set-Up

    DEFF Research Database (Denmark)

    Erik Weinell, Claus; Olsen, Kenneth N.; Christoffersen, Martin W.

    2003-01-01

    This work covers an experimental study of the drag resistance of different painted surfaces and simulated large-scale irregularities, viz. dry spraying, weld seams, barnacle fouling and paint remains. A laboratory scale rotary set-up was used to determine the drag resistance, and the surface...... roughness of the samples was determined by means of two different stylus-based methods, one having a 1.6 mm ball stylus (giving the macro-roughness) and the other having a needle type stylus (giving the micro-roughness). It is demonstrated that, in the case of ideal painted surfaces (low macro...

  7. Macrolide Resistance in Treponema pallidum Correlates With 23S rDNA Mutations in Recently Isolated Clinical Strains.

    Science.gov (United States)

    Molini, Barbara J; Tantalo, Lauren C; Sahi, Sharon K; Rodriguez, Veronica I; Brandt, Stephanie L; Fernandez, Mark C; Godornes, Charmie B; Marra, Christina M; Lukehart, Sheila A

    2016-09-01

    High rates of 23S rDNA mutations implicated in macrolide resistance have been identified in Treponema pallidum samples from syphilis patients in many countries. Nonetheless, some clinicians have been reluctant to abandon azithromycin as a treatment for syphilis, citing the lack of a causal association between these mutations and clinical evidence of drug resistance. Although azithromycin resistance has been demonstrated in vivo for the historical Street 14 strain, no recent T. pallidum isolates have been tested. We used the well-established rabbit model of syphilis to determine the in vivo efficacy of azithromycin against 23S rDNA mutant strains collected in 2004 to 2005 from patients with syphilis in Seattle, Wash. Groups of 9 rabbits were each infected with a strain containing 23S rDNA mutation A2058G (strains UW074B, UW189B, UW391B) or A2059G (strains UW228B, UW254B, and UW330B), or with 1 wild type strain (Chicago, Bal 3, and Mexico A). After documentation of infection, 3 animals per strain were treated with azithromycin, 3 were treated with benzathine penicillin G, and 3 served as untreated control groups. Treatment efficacy was documented by darkfield microscopic evidence of T. pallidum, serological response, and rabbit infectivity test. Azithromycin uniformly failed to cure rabbits infected with strains harboring either 23S rDNA mutation, although benzathine penicillin G was effective. Infections caused by wild type strains were successfully treated by either azithromycin or benzathine penicillin G. A macrolide resistant phenotype was demonstrated for all strains harboring a 23S rDNA mutation, demonstrating that either A2058G or A2059G mutation confers in vivo drug resistance.

  8. Library sequencing strategies for comparative analysis of stress resistance mechanisms in Escherichia coli strains

    DEFF Research Database (Denmark)

    Lennen, Rebecca; Bonde, Ida; Koza, Anna

    2014-01-01

    Transposon insertion sequencing (Tn-Seq) has recently emerged as a powerful next-generation sequencing method that enables querying the contributions of all genes in a bacterial genome toward the fitness of a growing organism. In this method, transposon insertion mutant libraries are constructed......-Seq to probe the basis for the large variations in osmotic and acetate stress tolerance of different laboratory strains of Escherichia coli (K-12 MG1655, BL21(DE3), W, and Crooks). Little is currently known to explain the source of this variation and to enable rational engineering to impart stress tolerance...

  9. Ultrashort peptide nanogels release in situ generated silver manoparticles to combat emerging antimicrobial resistance strains

    KAUST Repository

    Seferji, Kholoud

    2017-01-08

    Nanogels made from self-assembling ultrashort peptides (3-6 amino acids in size) are promising biomaterials for various biomedical applications such as tissue engineering, drug delivery, regenerative medicine, microbiology and biosensing.We have developed silver-releasing peptide nanogels with promising wound care applications. The peptide nanogels allow a precise control of in situ syntesized silver nanoparticles (AgNPs), using soley short UV radiation and no other chemical reducing agent. We propose these silver-releasing nanogels as excellent biomaterial to combat emerging antimicrobial resistant strains.

  10. Survey of strain distribution and antibiotic resistance pattern of group B streptococci (Streptococcus agalactiae isolated from clinical specimens

    Directory of Open Access Journals (Sweden)

    Mousavi, Seyed Masoud

    2016-09-01

    Full Text Available Aim: The aims of the present study were to determine the antibiotic susceptibility profils with particular emphasis on susceptible or resistant strains to macrolides and lincosamids antibiotics and to determine possible antibiotic resistance mechanisms occurring in group B streptococci (GBS strains using PCR assay and disk diffusion method.Methods: A total of 62 clinical GBS strains were investigated. Antibacterial susceptibility testing was performed using the disk diffusion method and inducible resistance test for clindamycin by standard double disk diffusion or D-zone test for all isolates to differentiate macrolide resistance phenotype (M, constitutive macrolide-lincosamide-streptogramin B phenotype (cMLS and induced macrolide-lincosamide-streptogramin B phenotype (iMLS. In addition, minimum inhibitory concentrations (MIC of penicillin were determined for all isolates. Finally, possible existence of antibiotic resistance genes for erythromycin , and and for clindamycin were examined among isolates using PCR assay.Results: All 62 isolates were susceptible to penicillin, ampicillin, linezolid, cefazoline and vancomycin. However, 93.5% (n=58 of isolates showed an increased MIC to penicillin. The overall rate of erythromycin resistance was 35.5% (n=22. All erythromycin-resistant isolates displayed the M phenotype (100%, n=22. All three erythromycin resistance genes (i.e. , and were found in erythromycin-resistant isolates.Conclusion: It was concluded that prescribing antibiotic without antibacterial susceptibility tests should be prevented because of the high prevalence of erythromycin-resistant GBS strains and the fact that erythromycin-resistant GBS strains has shown an increased MIC to penicillin, as the drug of choice for treating GBS infections.

  11. Characterization of a Large Antibiotic Resistance Plasmid Found in Enteropathogenic Escherichia coli Strain B171 and Its Relatedness to Plasmids of Diverse E. coli and Shigella Strains.

    Science.gov (United States)

    Hazen, Tracy H; Michalski, Jane; Nagaraj, Sushma; Okeke, Iruka N; Rasko, David A

    2017-09-01

    Enteropathogenic Escherichia coli (EPEC) is a leading cause of severe infantile diarrhea in developing countries. Previous research has focused on the diversity of the EPEC virulence plasmid, whereas less is known regarding the genetic content and distribution of antibiotic resistance plasmids carried by EPEC. A previous study demonstrated that in addition to the virulence plasmid, reference EPEC strain B171 harbors a second, larger plasmid that confers antibiotic resistance. To further understand the genetic diversity and dissemination of antibiotic resistance plasmids among EPEC strains, we describe the complete sequence of an antibiotic resistance plasmid from EPEC strain B171. The resistance plasmid, pB171_90, has a completed sequence length of 90,229 bp, a GC content of 54.55%, and carries protein-encoding genes involved in conjugative transfer, resistance to tetracycline ( tetA ), sulfonamides ( sulI ), and mercury, as well as several virulence-associated genes, including the transcriptional regulator hha and the putative calcium sequestration inhibitor ( csi ). In silico detection of the pB171_90 genes among 4,798 publicly available E. coli genome assemblies indicates that the unique genes of pB171_90 ( csi and traI ) are primarily restricted to genomes identified as EPEC or enterotoxigenic E. coli However, conserved regions of the pB171_90 plasmid containing genes involved in replication, stability, and antibiotic resistance were identified among diverse E. coli pathotypes. Interestingly, pB171_90 also exhibited significant similarity with a sequenced plasmid from Shigella dysenteriae type I. Our findings demonstrate the mosaic nature of EPEC antibiotic resistance plasmids and highlight the need for additional sequence-based characterization of antibiotic resistance plasmids harbored by pathogenic E. coli . Copyright © 2017 American Society for Microbiology.

  12. Resistance to papaya ringspot virus-watermelon strain (PRSV-W) in the desert watermelon Citrullus colocynthis

    Science.gov (United States)

    The bitter desert watermelon (Citrullus colocynthis) is a valuable source for improving disease or pest resistance in watermelon cultivars. The objective of this study was to identify C. colocynthis accessions displaying resistance to the papaya ringspot virus-watermelon strain (PRSV-W) that could ...

  13. Draft Genome Sequence of an Invasive Multidrug-Resistant Strain, Pseudomonas aeruginosa BK1, Isolated from a Keratitis Patient

    KAUST Repository

    Jeganathan, Lakshmi Priya

    2014-03-27

    Pseudomonas aeruginosa infections are difficult to treat due to the presence of a multitude of virulence factors and antibiotic resistance. Here, we report the draft genome sequence of P. aeruginosa BK1, an invasive and multidrug-resistant strain, isolated from a bacterial keratitis patient in southern India.

  14. PERCENTAGE OF CIPROFLOXACIN-RESISTANT STRAINS OF CITROBACTER FREUNDII IN ACUTE LEUKAEMIA PATIENTS WITH CIPROFLOXACIN PROPHYLAXIS

    Directory of Open Access Journals (Sweden)

    Rika Strauch

    2004-12-01

    Full Text Available Background. Authors tried to determine an efficiency of ciprofloxacin as infection prophylaxis in patients with acute leukaemia treated at the Department of Haematology in Clinical Center of Ljubljana. Due to cytotoxic chemotherapy, aplasia of bone marrow is inevitable. Therefore, these patients are at high risk for bacterial and fungal infection. The authors have noticed a rise in the number of ciprofloxacin-resistant strains of Citrobacter freundii and decided to find out if ciprofloxacin is still usable in this setting.Patients and methods. 45 patients with acute leukaemia were admitted to the Department of Haematology in the Clinical Center of Ljubljana during the year 2001 and 2002. All the patients received ciprofloxacin 2 × 500 mg on a daily basis. Citrobacter freundii was isolated in 11 patients, to whom we determined the proportion of ciprofloxacin-resistant strains of Citrobacter freundii and other Enterobacteriaceae. Susceptibility testing was done by the NCCCLS standards by the disc diffusion method and minimal inhibitory concentration.Results. C. freundii was isolated in 11 patients with AL. Extended-spectrum beta-lactamases (ESBL C. freundii was isolated in 6 patients (54.5%. Ciprofloxacin-resistant C. freundii was isolated in 6 patients (54.5%. Six patients (54.5% had ciprofloxacin-resistant C. freundii which was ESBL positive at the same time. In AL patients with C. freundii (n = 11 almost half of isolated bacteria were Gram negative bacilli (45.2%, n = 292, mostly from the family of Enterobacteriaceae. More than half of enterobacteria were ciprofloxacin-resistant, one third of them were also ESBL positive. Out of 131 enterobacteria, C. freundii was isolated 37 times. (28.2%.Conclusions. C. freundii was isolated in one fourth of AL patients. Half of the isolates were ciprofloxacin-resistant. The same was true for isolated enterobacteria. Almost all of ciprofloxacin-resistant bacteria were ESBL positive. There is a question

  15. Resistance Markers and Genetic Diversity in Acinetobacter baumannii Strains Recovered from Nosocomial Bloodstream Infections

    Directory of Open Access Journals (Sweden)

    Hanoch S. I. Martins

    2014-01-01

    Full Text Available In this study, phenotypic and genotypic methods were used to detect metallo-β-lactamases, cephalosporinases and oxacillinases and to assess genetic diversity among 64 multiresistant Acinetobacter baumannii strains recovered from blood cultures in five different hospitals in Brazil from December 2008 to June 2009. High rates of resistance to imipenem (93.75% and polymyxin B (39.06% were observed using the disk diffusion (DD method and by determining the minimum inhibitory concentration (MIC. Using the disk approximation method, thirty-nine strains (60.9% were phenotypically positive for class D enzymes, and 51 strains (79.6% were positive for cephalosporinase (AmpC. Using the E-test, 60 strains (93.75% were positive for metallo-β-lactamases (MβLs. All strains were positive for at least one of the 10 studied genes; 59 (92.1% contained blaVIM-1, 79.6% contained blaAmpC, 93.7% contained blaOXA23 and 84.3% contained blaOXA51. Enterobacteria Repetitive Intergenic Consensus (ERIC-PCR analysis revealed a predominance of certain clones that differed from each other. However, the same band pattern was observed in samples from the different hospitals studied, demonstrating correlation between the genotypic and phenotypic results. Thus, ERIC-PCR is an appropriate method for rapidly clustering genetically related isolates. These results suggest that defined clonal clusters are circulating within the studied hospitals. These results also show that the prevalence of MDR A. baumannii may vary among clones disseminated in specific hospitals, and they emphasize the importance of adhering to appropriate infection control measures.

  16. Genome sequencing and analysis of the first spontaneous Nanosilver resistant bacterium Proteus mirabilis strain SCDR1

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    Amr T. M. Saeb

    2017-11-01

    Full Text Available Abstract Background P. mirabilis is a common uropathogenic bacterium that can cause major complications in patients with long-standing indwelling catheters or patients with urinary tract anomalies. In addition, P. mirabilis is a common cause of chronic osteomyelitis in Diabetic foot ulcer (DFU patients. We isolated P. mirabilis SCDR1 from a Diabetic ulcer patient. We examined P. mirabilis SCDR1 levels of resistance against Nanosilver colloids, the commercial Nanosilver and silver containing bandages and commonly used antibiotics. We utilized next generation sequencing techniques (NGS, bioinformatics, phylogenetic analysis and pathogenomics in the characterization of the infectious pathogen. Results P. mirabilis SCDR1 was the first Nanosilver resistant isolate collected from a diabetic patient polyclonal infection. P. mirabilis SCDR1 showed high levels of resistance against Nanosilver colloids, Nanosilver chitosan composite and the commercially available Nanosilver and silver bandages. The P. mirabilis -SCDR1 genome size is 3,815,621 bp. with G + C content of 38.44%. P. mirabilis-SCDR1 genome contains a total of 3533 genes, 3414 coding DNA sequence genes, 11, 10, 18 rRNAs (5S, 16S, and 23S, and 76 tRNAs. Our isolate contains all the required pathogenicity and virulence factors to establish a successful infection. P. mirabilis SCDR1 isolate is a potential virulent pathogen that despite its original isolation site, the wound, can establish kidney infection and its associated complications. P. mirabilis SCDR1 contains several mechanisms for antibiotics and metals resistance, including, biofilm formation, swarming mobility, efflux systems, and enzymatic detoxification. Conclusion P. mirabilis SCDR1 is the first reported spontaneous Nanosilver resistant bacterial strain. P. mirabilis SCDR1 possesses several mechanisms that may lead to the observed Nanosilver resistance.

  17. Genetic analysis and mapping of genes for resistance to multiple strains of Soybean mosaic virus in a single resistant soybean accession PI 96983.

    Science.gov (United States)

    Yang, Yongqing; Zheng, Guijie; Han, Lu; Dagang, Wang; Yang, Xiaofeng; Yuan, Yuan; Huang, Saihua; Zhi, Haijian

    2013-07-01

    Soybean mosaic virus (SMV) is one of the most broadly distributed soybean (Glycine max (L.) Merr.) diseases and causes severe yield loss and seed quality deficiency. Multiple studies have proved that a single dominant gene can confer resistance to several SMV strains. Plant introduction (PI) 96983 has been reported to contain SMV resistance genes (e.g., Rsv1 and Rsc14) on chromosome 13. The objective of this study was to delineate the genetics of resistance to SMV in PI 96983 and determine whether one gene can control resistance to more than one Chinese SMV strain. In this study, PI 96983 was identified as resistant and Nannong 1138-2 was identified as susceptible to four SMV strains SC3, SC6, SC7, and SC17. Genetic maps based on 783 F2 individuals from the cross of PI 96983 × Nannong 1138-2 showed that the gene(s) conferring resistance to SC3, SC6, and SC17 were between SSR markers BARCSOYSSR_13_1114 and BARCSOYSSR_13_1136, whereas SC7 was between markers BARCSOYSSR_13_1140 and BARCSOYSSR_13_1185. The physical map based on 58 recombinant lines confirmed these results. The resistance gene for SC7 was positioned between BARCSOYSSR_13_1140 and BARCSOYSSR_13_1155, while the resistance gene(s) for SC3, SC6, and SC17 were between BARCSOYSSR_13_1128 and BARCSOYSSR_13_1136. We concluded that, there were two dominant resistance genes flanking Rsv1 or one of them at the reported genomic location of Rsv1. One of them (designated as "Rsc-pm") conditions resistance for SC3, SC6, and SC17 and another (designated as "Rsc-ps") confers resistance for SC7. The two tightly linked genes identified in this study would be helpful to cloning of resistance genes and breeding of multiple resistances soybean cultivars to SMV through marker-assisted selection (MAS).

  18. Acid resistance and response to pH-induced stress in two Lactobacillus plantarum strains with probiotic potential.

    Science.gov (United States)

    Šeme, H; Gjuračić, K; Kos, B; Fujs, Š; Štempelj, M; Petković, H; Šušković, J; Bogovič Matijašić, B; Kosec, G

    2015-01-01

    Two new Lactobacillus plantarum strains, KR6-DSM 28780 and M5 isolated from sour turnip and traditional dried fresh cheese, respectively, were evaluated for species identity, antibiotic susceptibility, resistance to gastrointestinal conditions and adaptive response to low pH. Resistance mechanisms involved in the adaptation to acid-induced stress in these two strains were investigated by quantitative PCR of the atpA, cfa1, mleS and hisD genes. In addition to absence of antibiotic resistance, the two L. plantarum strains showed excellent survival rates at pH values as low as 2.4. Adaptive response to low pH was clearly observed in both strains; strain KR6 was superior to M5, as demonstrated by its ability to survive during 3 h incubation at pH 2.0 upon adaptation to moderately acidic conditions. In contrast, acid adaptation did not significantly affect the survival rate during simulated passage through the gastrointestinal tract. In both strains, induction of histidine biosynthesis (hisD) was upregulated during the acid adaptation response. In addition, significant upregulation of the cfa1 gene, involved in modulation of membrane fatty acid composition, was observed during the adaptation phase in strain KR6 but not in strain M5. Cells adapted to moderately acidic conditions also showed a significantly increased viability after the lyophilisation procedure, a cross-protection phenomenon providing additional advantage in probiotic application.

  19. In vivo pathogenicity and resistance to phagocytosis of Streptococcus equi strains with different levels of capsule expression.

    Science.gov (United States)

    Anzai, T; Timoney, J F; Kuwamoto, Y; Fujita, Y; Wada, R; Inoue, T

    1999-07-01

    The glossy non-encapsulated strain of Steptococcus equi, NCTC 9682, was compared with the matt strain Hidaka/95/2 which expresses a medium sized capsule and with the mucoid CF32 which expresses a large sized capsule in phagocytosis assays and for virulence in inoculated horses. The three strains, NCTC 9682, Hidaka /95/2 and CF32 produced 2.0, 3.1, and 5.3 mg/g wet cells respectively after 3 h incubation, but similar amounts of M-like proteins, cytotoxin and mitogen. NCTC 9682 showed no resistance to phagocytosis by equine neutrophils regardless of the presence of opsonin while strains Hidaka /95/2 and CF32 showed almost complete resistance to phagocytosis. Furthermore, NCTC 9682 produced no clinical disease although it infected the guttural pouch and caused seroconversion. Typical strangles with guttural pouch invasion was observed in all horses infected with encapsulated strains.

  20. Designing and comparison study of rapid detection methods of resistance to injectable drugs in clinical strains of Mycobacterium tuberculosis

    Directory of Open Access Journals (Sweden)

    Fatemeh Salehi

    2012-01-01

    Full Text Available Introduction: In this study, some molecular methods were designed for rapid detection of resistance to kanamycin and amikacin.Materials and methods: Among 120 clinical isolates of mycobacterium tuberculosis, 70 strains were selected for evaluation of possible mutations. A PCR-RFLP method was designed for detection of wild type (using enzyme ajii and mutant from (BstFNI enzyme of the isolates. Furthermore, allele specific method (as PCR was designed for detection mutations in codons 1401 and 1402 gene rrs. Some selected isolates were sequenced.Results: In PCR-RFLP method, among the 70 strains examined by BstFNI enzyme, could detect 17 mutant strains among 24 phenotypicaly resistant and 44 non-mutant isolates from 46 susceptible isolates. The sensitivity of this method was %70.83 and specificity was %95.65 on the other hand, 12 mutant from 20 resistant strains and 29 non-mutant strains from 32 susceptible strains were detected by AjiI enzyme. The sensitivity and specificity of this method was 60 and %90.62, respectively. In MAS PCR, 3 mutants from 6 resistant strains and 12 non-mutants from 17 resistant strains were detected. The sensitivity of this method was 50 and specificity was 70.58. Results of sequencing method confirmed the results of molecular methods.Discussion and conclusion: PCR-RFLP method by BstFNI enzyme was the best method for rapid detection of Mycobacterium tuberculosis resistant to second-line injectable drugs and was recommended for routine use.

  1. Resistance to chemioantibiotics of Salmonella strains isolated from people employed in food production and distribution in 1982.

    Science.gov (United States)

    Gelosa, L; Falchi, M

    1984-01-01

    From healthy carriers, working in the alimentation field in the milanese area 2144 serotypes of Salmonella have been isolated in 1982, on which sensitivity towards 19 chemioantibiotics has been tested selecting them among those mostly employed in therapy. A remarkable resistance of isolated strains has been observed towards streptomycin (91.77%) and rifampicin (82.00%) and a low resistance towards sisomycin (1.21%) and cefotaxime (1.30%). 402 resistance patterns with various degree have been noticed towards up to 11 chemioantibiotics, particularly among Salmonella strains belonging to those of long lasting circulation of B, C and D serological groups. The importance from the epidemiological point of view of the presence of Salmonella strains with multiple resistance among staff working in the alimentation field is stressed, because they may be considered as incubation sites for the appearance of alimentary salmonellosis.

  2. The Behaviour of Laboratory Soil Electrical Resistivity Value under Basic Soil Properties Influences

    International Nuclear Information System (INIS)

    Hazreek, Z A M; Aziman, M; Azhar, A T S; Chitral, W D; Fauziah, A; Rosli, S

    2015-01-01

    Electrical resistivity method (ERM) was a popular indirect geophysical tools adopted in engineering, environmental and archaeological studies. In the past, results of the electrical resistivity value (ERV) were always subjected to a long discussion and debate among the related parties such as an engineers, geophysicists and geologists due to its lack of clarification and evidences in quantitative point of view. Most of the results produced in the past was always been justified using qualitative ways which difficult to be accept by certain parties. In order to reduce the knowledge gap between those parties, this study has performed a laboratory experiment of soil box resistivity test which supported by an additional basic geotechnical test as referred to particle size distribution test (d), moisture content test (w), density test (ρ bulk ) and Atterberg limit test (LL, PL and PI). The test was performed to establish a series of electrical resistivity value with different quantity of water content for Clayey SILT and Silty SAND soil. It was found that the ERV of Silty SAND (600 - 7300 Ωm) was higher than Clayey SILT (13 - 7700 Ωm) due to the different quantity of basic soil properties value obtained from the basic geotechnical test. This study was successfully demonstrated that the fluctuation of ERV has greatly influenced by the variations of the soil physical properties (d, w, ρ bulk , LL, PL and PI). Hence, the confidence level of ERV interpretation will be increasingly meaningful since it able to be proved by others parameter generated by laboratory direct test

  3. Multi drug resistance of campylobacter jejuni and campylobacter coli to tested antibiotics in strains originating from humans, poultry and swine

    Directory of Open Access Journals (Sweden)

    Tambur Zoran Ž.

    2010-01-01

    Full Text Available Thermophilic Campylobacter are among the most common cause of bacterial enteritis in humans. Food animals are considered one of the most important sources of Campylobacter causing infections in man. Campylobacter infection is clinically mild and resolves spontaneously. In severe or long-lasting cases, treatment with antibiotics is necessary. Resistance of Campylobacter spp. to drugs used in treatment of infection is a matter of concern. The aim of this paper is to determine presence of multi drug resistant strains of Campylobacter jejuni and Campylobacter coli isolated from animals and man. Material for testing was obtained by scraping the cecum surface from boilers, pig cecum and colon, and human feces. For isolation Campylobacter jejuni and Campylobacter coli microaerophilic conditions, temperature of 42°C and antibiotic supplement were required to inhibit the growth of other intestinal bacteria. In this research, for sensitivity testing of Campylobacter jejuni and Campylobacter coli three different methods were used: disc diffusion test, E-test, and dilution agar method. A total of 55 strains of Campylobacter jejuni and Campylobacter coli. Out of the total, 24 strains originated from man, 16 from broilers were isolated, and 15 from pigs. Multidrug resistance was determined in cases when the strains were resistant to two or more antibiotics. Applying E-test, we detected that the largest number of Campylobacter jejuni were multi drug resistant to two antibiotics (41.2%, and three antibiotics (11.8%. Applying disc diffusion method it was detected that 5.9% of Campylobacter jejuni from man was resistant to four tested antibiotics. Applying all three methods, it was detected that the largest number of Campylobacter strains was resistant to two antibiotics and three antibiotics. Applying disc diffusion method it was detected that 50% of Campylobacter coli strains from pigs were resistant to three tested antibiotics.

  4. Genome Sequence of the Multiantibiotic-Resistant Enterococcus faecium Strain C68 and Insights on the pLRM23 Colonization Plasmid

    OpenAIRE

    Garc?a-Solache, M?nica; Rice, Louis B.

    2016-01-01

    Enterococcus faecium infections are a rising concern in hospital settings. Vancomycin-resistant enterococci colonize the gastrointestinal tract and replace nonresistant strains, complicating the treatment of debilitated patients. Here, we present a polished genome of the multiantibiotic-resistant strain C68, which was obtained as a clinical isolate and is a useful experimental strain.

  5. Antibacterial Activity of Glutathione-Stabilized Silver Nanoparticles Against Campylobacter Multidrug-Resistant Strains

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    Jose M. Silvan

    2018-03-01

    Full Text Available Campylobacter is the leading cause of bacterial diarrheal disease worldwide. Although most episodes of campylobacteriosis are self-limiting, antibiotic treatment is usually needed in patients with serious enteritis, and especially in childrens or the elderly. In the last years, antibiotic resistance in Campylobacter has become a major public health concern and a great interest exists in developing new antimicrobial strategies for reducing the impact of this food-borne pathogen on human health. Among them, the use of silver nanoparticles as antibacterial agents has taken on increased importance in the field of medicine. The aim of the present study was to evaluate the antimicrobial effectiveness of glutathione-stabilized silver nanoparticles (GSH-Ag NPs against multidrug resistant (MDR Campylobacter strains isolated from the chicken food chain (FC and clinical patients (C. The results obtained showed that GSH-Ag NPs were highly effective against all MDR Campylobacter strains tested. The minimal inhibitory concentration (MIC and minimal bactericidal concentration (MBC were in a range from 4.92 to 39.4 μg/mL and 9.85 to 39.4 μg/mL, respectively. Cytotoxicity assays were also assessed using human intestinal HT-29, Caco-2, and CCD-18 epithelial cells. Exposure of GSH-Ag NPs to intestinal cells showed a dose-dependent cytotoxic effect in all cell lines between 9.85 and 39.4 μg/mL. More than 60% of the tested Campylobacter strains were susceptible to GSH-Ag NPs concentrations ≤ 9.85 μg/mL, suggesting that practical inhibitory levels could be reached at low GSH-Ag NPs concentrations. Further works are needed with the purpose to evaluate the practical implications of the toxicity studies and to know more about other attributes linked to the biological compatibility. This behavior makes GSH-Ag NPs as a promising tool for the design of novel antibacterial agents for controlling Campylobacter.

  6. Identification of methicillin-resistant Staphylococcus aureus (MRSA) strains isolated from burn patients by multiplex PCR.

    Science.gov (United States)

    Montazeri, Effat Abbasi; Khosravi, Azar Dokht; Jolodar, Abbas; Ghaderpanah, Mozhgan; Azarpira, Samireh

    2015-05-01

    Methicillin-resistant Staphylococcus aureus (MRSA) and methicillin-resistant coagulase-negative staphylococci (MRCoNS) as important human pathogens are causes of nosocomial infections worldwide. Burn patients are at a higher risk of local and systemic infections with these microorganisms. A screening method for MRSA by using a multiplex polymerase chain reaction (PCR) targeting the 16S ribosomal RNA (rRNA), mecA, and nuc genes was developed. The aim of the present study was to investigate the potential of this PCR assay for the detection of MRSA strains in samples from burn patients. During an 11-month period, 230 isolates (53.11%) of Staphylococcus spp. were collected from burn patients. The isolates were identified as S. aureus by using standard culture and biochemical tests. DNA was extracted from bacterial colonies and multiplex PCR was used to detect MRSA and MRCoNS strains. Of the staphylococci isolates, 149 (64.9%) were identified as S. aureus and 81 (35.21%) were described as CoNS. Among the latter, 51 (62.97%) were reported to be MRCoNS. From the total S. aureus isolates, 132 (88.6%) were detected as MRSA and 17 (11.4%) were methicillin-susceptible S. aureus (MSSA). The presence of the mecA gene in all isolates was confirmed by using multiplex PCR as a gold standard method. This study presented a high MRSA rate in the region under investigation. The 16S rRNA-mecA-nuc multiplex PCR is a good tool for the rapid characterization of MRSA strains. This paper emphasizes the need for preventive measures and choosing effective antimicrobials against MRSA and MRCoNS infections in the burn units. Copyright © 2014 Elsevier Ltd and ISBI. All rights reserved.

  7. Strain fields in Boeing 737 fuselage lap splices : field and laboratory measurements with analytical correlations

    Science.gov (United States)

    1995-06-01

    In support of the Federal Aviation Administration Technical Center's (FAATC) National Aging Aircraft Research Program (NAARP), Sandia National Laboratories and the John A. Volpe National Transportation Systems Center (Volpe Center) are conducting res...

  8. Transcription analysis of recombinant industrial and laboratory Saccharomyces cerevisiae strains reveals the molecular basis for fermentation of glucose and xylose.

    Science.gov (United States)

    Matsushika, Akinori; Goshima, Tetsuya; Hoshino, Tamotsu

    2014-01-28

    There has been much research on the bioconversion of xylose found in lignocellulosic biomass to ethanol by genetically engineered Saccharomyces cerevisiae. However, the rate of ethanol production from xylose in these xylose-utilizing yeast strains is quite low compared to their glucose fermentation. In this study, two diploid xylose-utilizing S. cerevisiae strains, the industrial strain MA-R4 and the laboratory strain MA-B4, were employed to investigate the differences between anaerobic fermentation of xylose and glucose, and general differences between recombinant yeast strains, through genome-wide transcription analysis. In MA-R4, many genes related to ergosterol biosynthesis were expressed more highly with glucose than with xylose. Additionally, these ergosterol-related genes had higher transcript levels in MA-R4 than in MA-B4 during glucose fermentation. During xylose fermentation, several genes related to central metabolic pathways that typically increase during growth on non-fermentable carbon sources were expressed at higher levels in both strains. Xylose did not fully repress the genes encoding enzymes of the tricarboxylic acid and respiratory pathways, even under anaerobic conditions. In addition, several genes involved in spore wall metabolism and the uptake of ammonium, which are closely related to the starvation response, and many stress-responsive genes mediated by Msn2/4p, as well as trehalose synthase genes, increased in expression when fermenting with xylose, irrespective of the yeast strain. We further observed that transcript levels of genes involved in xylose metabolism, membrane transport functions, and ATP synthesis were higher in MA-R4 than in MA-B4 when strains were fermented with glucose or xylose. Our transcriptomic approach revealed the molecular events underlying the response to xylose or glucose and differences between MA-R4 and MA-B4. Xylose-utilizing S. cerevisiae strains may recognize xylose as a non-fermentable carbon source, which

  9. Laboratory evaluation of the ESwab transport system for the recovery of carbapenem-resistant Acinetobacter baumannii.

    Science.gov (United States)

    Moran-Gilad, J; Schwartz, D; Navon-Venezia, S; Carmeli, Y

    2012-07-01

    Microbiological surveillance for detection of carbapenem-resistant A. baumannii is important, but recovery of A. baumannii is inadequate. We studied A. baumannii recovery by a particular transport system that is possibly superior over standard swabs, using reference and clinical strains. First, the recovery rates relating to the various swabs were compared with regard to various combinations of transport times (0 h, 1 h, 24 h, 48 h), storage times (0 weeks, 1 week, 2 weeks, 4 weeks) and storage temperatures (4°c,-80°c) using live counts. Second, the recovery of different inocula of strains mixed with fecal microbiota was evaluated by plating on selective medium. The new transport system exhibited a decline of system performed well, even after prolonged transport or with a low inoculum, and its processing could be delayed by up to 2 weeks, especially if refrigerated. The new transport system may thus enhance A. baumannii surveillance.

  10. Direct sequencing for rapid detection of multidrug resistant Mycobacterium tuberculosis strains in Morocco

    Directory of Open Access Journals (Sweden)

    Zakham F

    2013-11-01

    Full Text Available Fathiah Zakham,1,4 Imane Chaoui,1 Amina Hadbae Echchaoui,2 Fouad Chetioui,3 My Driss Elmessaoudi,3 My Mustapha Ennaji,4 Mohammed Abid,2 Mohammed El Mzibri11Unité de Biologie et Recherché Médicale, Centre National de l'Energie, des Sciences et des Techniques Nucléaires (CNESTEN, Rabat, 2Laboratoire de Génétique Mycobacterienne, Institut Pasteur, Tangier, 3Laboratoire de Tuberculose Institut Pasteur, Casablanca, 4Laboratoire de Microbiologie, Hygiène et Virologie, Faculté des Sciences et Techniques, Mohammedia, MoroccoBackground: Tuberculosis (TB is a major public health problem with high mortality and morbidity rates, especially in low-income countries. Disturbingly, the emergence of multidrug resistant (MDR and extensively drug resistant (XDR TB cases has worsened the situation, raising concerns of a future epidemic of virtually untreatable TB. Indeed, the rapid diagnosis of MDR TB is a critical issue for TB management. This study is an attempt to establish a rapid diagnosis of MDR TB by sequencing the target fragments of the rpoB gene which linked to resistance against rifampicin and the katG gene and inhA promoter region, which are associated with resistance to isoniazid.Methods: For this purpose, 133 sputum samples of TB patients from Morocco were enrolled in this study. One hundred samples were collected from new cases, and the remaining 33 were from previously treated patients (drug relapse or failure, chronic cases and did not respond to anti-TB drugs after a sufficient duration of treatment. All samples were subjected to rpoB, katG and pinhA mutation analysis by polymerase chain reaction and DNA sequencing.Results: Molecular analysis showed that seven strains were isoniazid-monoresistant and 17 were rifampicin-monoresistant. MDR TB strains were identified in nine cases (6.8%. Among them, eight were traditionally diagnosed as critical cases, comprising four chronic and four drug-relapse cases. The last strain was isolated from a

  11. Carbapenem-resistant-only Pseudomonas aeruginosa infection in patients formerly infected by carbapenem-susceptible strains.

    Science.gov (United States)

    Tsai, Ming-Han; Wu, Tsu-Lan; Su, Lin-Hui; Lo, Wei-Lin; Chen, Chyi-Liang; Liang, Yi-Hua; Chiu, Cheng-Hsun

    2014-12-01

    Pseudomonas aeruginosa isolates that were initially carbapenem-susceptible and later became selective carbapenem-resistant following antimicrobial therapy were identified from individual cases during the same hospitalisation. Cross-resistance to other β-lactams was not found and their susceptibilities remained identical in consecutive isolates. Real-time quantitative reverse transcription PCR was performed to investigate the role of OprD, an outer membrane protein regulating the entry of carbapenems, in the appearance of carbapenem-resistant-only P. aeruginosa (CROPA). Fifteen paired isolates of carbapenem-susceptible P. aeruginosa (CS-PA) and CROPA were identified. All of the cases had carbapenem exposure history within 1 month before the appearance of CROPA (mean 10 days). Reduced OprD expression was found in 93% (14/15) of the isolates, suggesting that oprD inactivation was the major contributor to selective carbapenem resistance. Of the 14 cases with CROPA due to oprD mutation, 71% (10/14) were persistent infection, as genotype analysis revealed that their paired strains were isogenic; 29% (4/14) represented re-infections as they were heterogenic, suggesting that oprD-deficient CROPA existed in the hospital and that carbapenem selective pressure promoted its spread to patients. We conclude that CROPA may occur soon after the use of carbapenems to treat CS-PA infections and that oprD mutation is the major mechanism of resistance in CROPA. Restriction of empirical use of carbapenems by antibiotic stewardship is important to halt the occurrence of CROPA. Copyright © 2014 Elsevier B.V. and the International Society of Chemotherapy. All rights reserved.

  12. Genetic pathway in acquisition and loss of vancomycin resistance in a methicillin resistant Staphylococcus aureus (MRSA strain of clonal type USA300.

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    Susana Gardete

    2012-02-01

    Full Text Available An isolate of the methicillin-resistant Staphylococcus aureus (MRSA clone USA300 with reduced susceptibility to vancomycin (SG-R (i.e, vancomycin-intermediate S. aureus, VISA and its susceptible "parental" strain (SG-S were recovered from a patient at the end and at the beginning of an unsuccessful vancomycin therapy. The VISA phenotype was unstable in vitro generating a susceptible revertant strain (SG-rev. The availability of these 3 isogenic strains allowed us to explore genetic correlates of antibiotic resistance as it emerged in vivo. Compared to the susceptible isolate, both the VISA and revertant strains carried the same point mutations in yycH, vraG, yvqF and lspA genes and a substantial deletion within an intergenic region. The revertant strain carried a single additional frameshift mutation in vraS which is part of two component regulatory system VraSR. VISA isolate SG-R showed complex alterations in phenotype: decreased susceptibility to other antibiotics, slow autolysis, abnormal cell division and increased thickness of cell wall. There was also altered expression of 239 genes including down-regulation of major virulence determinants. All phenotypic properties and gene expression profile returned to parental levels in the revertant strain. Introduction of wild type yvqF on a multicopy plasmid into the VISA strain caused loss of resistance along with loss of all the associated phenotypic changes. Introduction of the wild type vraSR into the revertant strain caused recovery of VISA type resistance. The yvqF/vraSR operon seems to function as an on/off switch: mutation in yvqF in strain SG-R turns on the vraSR system, which leads to increase in vancomycin resistance and down-regulation of virulence determinants. Mutation in vraS in the revertant strain turns off this regulatory system accompanied by loss of resistance and normal expression of virulence genes. Down-regulation of virulence genes may provide VISA strains with a "stealth

  13. Prevalence of Resistant Strains of Rhipicephalus microplus to Acaricides in Cattle Ranch in the Tropical Region of Tecpan of Galeana, Guerrero, Mexico

    Directory of Open Access Journals (Sweden)

    J. Olivares-Pérez*, S. Rojas-Hernández, M.T. Valencia-Almazan, I. Gutiérrez-Segura and E.J. Míreles-Martínez

    2011-10-01

    Full Text Available Tick and tick borne diseases cause many problems to the cattle industry worldwide. The prevalence of resistant strains of Rhipicephalus microplus to different acaricides on cattle farms in the tropical region of Tecpan of Galeana, Guerrero, Mexico, and risk factors related to prevalence of resistant strains of R. microplus. Sixty one ranches infested were sampled; in each ranch were collected 30-50 fully-engorged female R. microplus ticks, of 10 cattle randomly selected, and evaluated in their progeny resistance to acaricides, using the larval packet test. The prevalence of resistant strains was total pyrethroids and amitraz. In organophosphorus 31.1, 48.3 and 82.2% of strains were resistant to clorpyriphos, coumaphos and diazinon, respectively. Risk factors favored (P<0.05 the development of resistant strains of acaricides. We concluded that the resistance of R. microplus to acaricides used to control a problem, and risk factors (livestock management have accelerated the development of resistance.

  14. What is the mechanism for persistent coexistence of drug-susceptible and drug-resistant strains of Streptococcus pneumoniae?

    Science.gov (United States)

    Colijn, Caroline; Cohen, Ted; Fraser, Christophe; Hanage, William; Goldstein, Edward; Givon-Lavi, Noga; Dagan, Ron; Lipsitch, Marc

    2010-01-01

    The rise of antimicrobial resistance in many pathogens presents a major challenge to the treatment and control of infectious diseases. Furthermore, the observation that drug-resistant strains have risen to substantial prevalence but have not replaced drug-susceptible strains despite continuing (and even growing) selective pressure by antimicrobial use presents an important problem for those who study the dynamics of infectious diseases. While simple competition models predict the exclusion of one strain in favour of whichever is ‘fitter’, or has a higher reproduction number, we argue that in the case of Streptococcus pneumoniae there has been persistent coexistence of drug-sensitive and drug-resistant strains, with neither approaching 100 per cent prevalence. We have previously proposed that models seeking to understand the origins of coexistence should not incorporate implicit mechanisms that build in stable coexistence ‘for free’. Here, we construct a series of such ‘structurally neutral’ models that incorporate various features of bacterial spread and host heterogeneity that have been proposed as mechanisms that may promote coexistence. We ask to what extent coexistence is a typical outcome in each. We find that while coexistence is possible in each of the models we consider, it is relatively rare, with two exceptions: (i) allowing simultaneous dual transmission of sensitive and resistant strains lets coexistence become a typical outcome, as does (ii) modelling each strain as competing more strongly with itself than with the other strain, i.e. self-immunity greater than cross-immunity. We conclude that while treatment and contact heterogeneity can promote coexistence to some extent, the in-host interactions between strains, particularly the interplay between coinfection, multiple infection and immunity, play a crucial role in the long-term population dynamics of pathogens with drug resistance. PMID:19940002

  15. Effect of antimicrobial peptides on colistin-susceptible and colistin-resistant strains of Klebsiella pneumoniae and Enterobacter asburiae.

    Science.gov (United States)

    Kádár, Béla; Kocsis, Béla; Kristof, Katalin; Tóth, Ákos; Szabó, Dóra

    2015-12-01

    In this study susceptibility to different antimicrobial peptides was investigated on colistin-susceptible and colistin-resistant identical pulsotype strains of KPC-2 producing Klebsiella pneumoniae ST258 as well as colistin-susceptible and colistin-resistant Enterobacter asburiae strains isolated from clinical samples. In our test, bacteria were exposed to 50 mg/ml lactoferrin, lysozyme and protamine - cationic antimicrobial peptides belonging to innate immune system and having structural similarity to polymyxins - in separate reactions. After 18 hours incubation of colonies were counted. 40% of colistin-resistant K. pneumoniae strains and 97% of colistin-susceptible counterpart strains were lysed by protamine whereas 87% and 100% colony forming unit decrease by lysozyme was seen, respectively. In the case of colistin-resistant E. asburiae strains 1 log10 cell count increase were observed after treatment with lysozyme and 1.56 log10 after lactoferrin exposure compared to the initial number whereas the colistin-susceptible showed no relevant cell count increase. Our findings suggest that acquired colistin-resistance in Enterobacteriaceae is associated with tolerance against antimicrobial peptides.

  16. Activity of ceftobiprole against methicillin-resistant Staphylococcus aureus strains with reduced susceptibility to daptomycin, linezolid or vancomycin, and strains with defined SCCmec types.

    Science.gov (United States)

    Farrell, David J; Flamm, Robert K; Sader, Helio S; Jones, Ronald N

    2014-04-01

    Ceftobiprole is a broad-spectrum cephalosporin with activity against methicillin-resistant Staphylococcus aureus (MRSA) and Gram-negative pathogens including Pseudomonas aeruginosa. The aim of this study was to evaluate the activity of ceftobiprole against MRSA isolates with decreased susceptibility to daptomycin, linezolid or vancomycin as well as isolates from staphylococcal chromosome cassette mec (SCCmec) types I, II, III and IV. Overall, ceftobiprole demonstrated high potency against the 216 isolates tested, with MIC50 and MIC90 values (minimum inhibitory concentrations required to inhibit 50% and 90% of the isolates, respectively) of 1mg/L and 2mg/L (97.2% susceptible). The MIC90 for ceftobiprole was 2mg/L against the linezolid-non-susceptible, daptomycin-non-susceptible and vancomycin-intermediate (VISA and hVISA) subsets and was 1mg/L against the vancomycin-resistant (VRSA) strains. The MIC50/90 values for ceftobiprole were 2/4, 1/2, 2/2 and 1/1mg/L against SCCmec types I, II, III and IV, respectively. SCCmec type I strains had the highest MICs, with six strains exhibiting a ceftobiprole MIC of 4mg/L and 15 strains at 2mg/L. Ceftobiprole demonstrated potent activity against MRSA, including subsets of isolates with reduced susceptibility to daptomycin, linezolid and vancomycin. The activity of ceftobiprole against these resistant phenotypes indicates that it may have clinical utility in the treatment of infections caused by multidrug-resistant S. aureus and across strains from prevalent SCCmec types. Copyright © 2013 Elsevier B.V. and the International Society of Chemotherapy. All rights reserved.

  17. Antimicrobial-resistant patterns of Escherichia coli and Salmonella strains in the aquatic Lebanese environments

    International Nuclear Information System (INIS)

    Harakeh, Steve; Yassine, Hadi; El-Fadel, Mutasem

    2006-01-01

    This study is the first to be conducted in Lebanon on the isolation and molecular characterization and the antimicrobial resistance profile of environmental pathogenic bacterial strains. Fifty-seven samples of seawater, sediment, crab, and fresh water were collected during the spring and summer seasons of 2003. The isolation of Escherichia coli and Salmonella using appropriate selective media revealed that 94.7% of the tested samples were contaminated with one or both of the tested bacteria. The polymerase chain reaction (PCR) was then used to identify the species of both bacteria using various sets of primers. Many pathogenic E. coli isolates were detected by PCR out of which two were identified as O157:H7 E. coli. Similarly, the species of many of the Salmonella isolates was molecularly identified. The confirmed isolates of Salmonella and E. coli were then tested using the disk diffusion method for their susceptibility to four different antimicrobials revealing high rates of antimicrobial resistance. - First report of antibiotic resistance in bacteria in the environment in Lebanon

  18. Uncertainty Analysis of Resistance Tests in Ata Nutku Ship Model Testing Laboratory of Istanbul Technical University

    Directory of Open Access Journals (Sweden)

    Cihad DELEN

    2015-12-01

    Full Text Available In this study, some systematical resistance tests, where were performed in Ata Nutku Ship Model Testing Laboratory of Istanbul Technical University (ITU, have been included in order to determine the uncertainties. Experiments which are conducted in the framework of mathematical and physical rules for the solution of engineering problems, measurements, calculations include uncertainty. To question the reliability of the obtained values, the existing uncertainties should be expressed as quantities. The uncertainty of a measurement system is not known if the results do not carry a universal value. On the other hand, resistance is one of the most important parameters that should be considered in the process of ship design. Ship resistance during the design phase of a ship cannot be determined precisely and reliably due to the uncertainty resources in determining the resistance value that are taken into account. This case may cause negative effects to provide the required specifications in the latter design steps. The uncertainty arising from the resistance test has been estimated and compared for a displacement type ship and high speed marine vehicles according to ITTC 2002 and ITTC 2014 regulations which are related to the uncertainty analysis methods. Also, the advantages and disadvantages of both ITTC uncertainty analysis methods have been discussed.

  19. Whole Genome Sequencing Investigation of a Tuberculosis Outbreak in Port-au-Prince, Haiti Caused by a Strain with a "Low-Level" rpoB Mutation L511P - Insights into a Mechanism of Resistance Escalation.

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    Oksana Ocheretina

    Full Text Available The World Health Organization recommends diagnosing Multidrug-Resistant Tuberculosis (MDR-TB in high burden countries by detection of mutations in Rifampin (RIF Resistance Determining Region of Mycobacterium tuberculosis rpoB gene with rapid molecular tests GeneXpert MTB/RIF and Hain MTBDRplus. Such mutations are found in >95% of Mycobacterium tuberculosis strains resistant to RIF by conventional culture-based drug susceptibility testing (DST. However routine diagnostic screening with molecular tests uncovered specific "low level" rpoB mutations conferring resistance to RIF below the critical concentration of 1 μg/ml in some phenotypically susceptible strains. Cases with discrepant phenotypic (susceptible and genotypic (resistant results for resistance to RIF account for at least 10% of resistant diagnoses by molecular tests and urgently require new guidelines to inform therapeutic decision making. Eight strains with a "low level" rpoB mutation L511P were isolated by GHESKIO laboratory between 2008 and 2012 from 6 HIV-negative and 2 HIV-positive patients during routine molecular testing. Five isolates with a single L511P mutation and two isolates with double mutation L511P&M515T had MICs for RIF between 0.125 and 0.5 μg/ml and tested susceptible in culture-based DST. The eighth isolate carried a double mutation L511P&D516C and was phenotypically resistant to RIF. All eight strains shared the same spoligotype SIT 53 commonly found in Haiti but classic epidemiological investigation failed to uncover direct contacts between the patients. Whole Genome Sequencing (WGS revealed that L511P cluster isolates resulted from a clonal expansion of an ancestral strain resistant to Isoniazid and to a very low level of RIF. Under the selective pressure of RIF-based therapy the strain acquired mutation in the M306 codon of embB followed by secondary mutations in rpoB and escalation of resistance level. This scenario highlights the importance of subcritical

  20. Enhanced chlorine resistance of tap water-adapted Legionella pneumophila as compared with agar medium-passaged strains.

    Science.gov (United States)

    Kuchta, J M; States, S J; McGlaughlin, J E; Overmeyer, J H; Wadowsky, R M; McNamara, A M; Wolford, R S; Yee, R B

    1985-07-01

    Previous studies have shown that bacteria maintained in a low-nutrient "natural" environment such as swimming pool water are much more resistant to disinfection by various chemical agents than strains maintained on rich media. In the present study a comparison was made of the chlorine (Cl2) susceptibility of hot-water tank isolates of Legionella pneumophila maintained in tap water and strains passaged on either nonselective buffered charcoal-yeast extract or selective differential glycine-vancomycin-polymyxin agar medium. Our earlier work has shown that environmental and clinical isolates of L. pneumophila maintained on agar medium are much more resistant to Cl2 than coliforms are. Under the present experimental conditions (21 degrees C, pH 7.6 to 8.0, and 0.25 mg of free residual Cl2 per liter, we found the tap water-maintained L. pneumophila strains to be even more resistant than the agar-passaged isolates. Under these conditions, 99% kill of tap water-maintained strains of L. pneumophila was usually achieved within 60 to 90 min compared with 10 min for agar-passaged strains. Samples from plumbing fixtures in a hospital yielded legionellae which were "super"-chlorine resistant when assayed under natural conditions. After one agar passage their resistance dropped to levels of comparable strains which had not been previously exposed to additional chlorination. These studies more closely approximate natural conditions than our previous work and show that tap water-maintained L. pneumophila is even more resistant to Cl2 than its already resistant agar medium-passaged counterpart.

  1. Infection of equine monocyte-derived macrophages with an attenuated equine infectious anemia virus (EIAV) strain induces a strong resistance to the infection by a virulent EIAV strain.

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    Ma, Jian; Wang, Shan-Shan; Lin, Yue-Zhi; Liu, Hai-Fang; Liu, Qiang; Wei, Hua-Mian; Wang, Xue-Feng; Wang, Yu-Hong; Du, Cheng; Kong, Xian-Gang; Zhou, Jian-Hua; Wang, Xiaojun

    2014-08-09

    The Chinese attenuated equine infectious anemia virus (EIAV) vaccine has successfully protected millions of equine animals from EIA disease in China. Given that the induction of immune protection results from the interactions between viruses and hosts, a better understanding of the characteristics of vaccine strain infection and host responses would be useful for elucidating the mechanism of the induction of immune protection by the Chinese attenuated EIAV strain. In this study, we demonstrate in equine monocyte-derived macrophages (eMDM) that EIAVFDDV13, a Chinese attenuated EIAV strain, induced a strong resistance to subsequent infection by a pathogenic strain, EIAVUK3. Further experiments indicate that the expression of the soluble EIAV receptor sELR1, Toll-like receptor 3 (TLR3) and interferon β (IFNβ) was up-regulated in eMDM infected with EIAVFDDV13 compared with eMDM infected with EIAVUK3. Stimulating eMDM with poly I:C resulted in similar resistance to EIAV infection as induced by EIAVFDDV13 and was correlated with enhanced TLR3, sELR1 and IFNβ expression. The knock down of TLR3 mRNA significantly impaired poly I:C-stimulated resistance to EIAV, greatly reducing the expression of sELR1 and IFNβ and lowered the level of infection resistance induced by EIAVFDDV13. These results indicate that the induction of restraining infection by EIAVFDDV13 in macrophages is partially mediated through the up-regulated expression of the soluble viral receptor and IFNβ, and that the TLR3 pathway activation plays an important role in the development of an EIAV-resistant intracellular environment.

  2. An Investigation of Antibiotic Resistance Pattern in the Strains of Methicillin-resistant Staphylococcus epidermidis Isolated From Clinical Samples in Isfahan Province, Iran

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    Fahimeh Nourbakhsh

    2016-08-01

    Full Text Available Background and Objectives: Staphylococcus epidermidis is one of the effective factors causing nosocomial infections. This study was performed to investigate the antibiotic resistance pattern in the methicillin-resistant S. epidermidis strains isolated from clinical samples in Isfahan Province. Methods: In this descriptive cross-sectional study, 150 isolates of S. epidermidis were isolated from detected from the patients hospitalized in hospitals and treatment centers of Isfahan City. The antibiotic resistance pattern was evaluated by disk diffusion method. The presence of the gene encoding antibiotic resistance to methicillin (mec A in the isolates were investigated using PCR method. Data were analyzed with Chi-square and Fisher's exact statistical tests. Results: In this study, most isolates were related to urinary tract infections. The highest resistance was reported to penicillin (98.9%, erythromycin (89.4%, ciprofloxacin (77.7%, clindamycin (65.9%, tetracycline (63.2%, and meticillin (54%. None of the strains showed resistance to vancomycin and linezolid. Molecular studies indicated the presence of mecA gene in 76% of the studied isolates. Conclusion: According to the results of this study, vancomycin and linezolid antibiotics can be the best choice of treatment for infections caused by S. epidermidis. Also, high resistance of S. epidermidis can be a serious warning for increased multiple antibiotic resistance. Molecular studies are indicative of high sensitivity of molecular methods in the investigation of methicillin-resistant isolates.  

  3. Genomic, Transcriptomic and Metabolomic Studies of Two Well-Characterized, Laboratory-Derived Vancomycin-Intermediate Staphylococcus aureus Strains Derived from the Same Parent Strain

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    Dipti S. Hattangady

    2015-02-01

    Full Text Available Complete genome comparisons, transcriptomic and metabolomic studies were performed on two laboratory-selected, well-characterized vancomycin-intermediate Staphylococcus aureus (VISA derived from the same parent MRSA that have changes in cell wall composition and decreased autolysis. A variety of mutations were found in the VISA, with more in strain 13136p−m+V20 (vancomycin MIC = 16 µg/mL than strain 13136p−m+V5 (MIC = 8 µg/mL. Most of the mutations have not previously been associated with the VISA phenotype; some were associated with cell wall metabolism and many with stress responses, notably relating to DNA damage. The genomes and transcriptomes of the two VISA support the importance of gene expression regulation to the VISA phenotype. Similarities in overall transcriptomic and metabolomic data indicated that the VISA physiologic state includes elements of the stringent response, such as downregulation of protein and nucleotide synthesis, the pentose phosphate pathway and nutrient transport systems. Gene expression for secreted virulence determinants was generally downregulated, but was more variable for surface-associated virulence determinants, although capsule formation was clearly inhibited. The importance of activated stress response elements could be seen across all three analyses, as in the accumulation of osmoprotectant metabolites such as proline and glutamate. Concentrations of potential cell wall precursor amino acids and glucosamine were increased in the VISA strains. Polyamines were decreased in the VISA, which may facilitate the accrual of mutations. Overall, the studies confirm the wide variability in mutations and gene expression patterns that can lead to the VISA phenotype.

  4. Biofilm formation and sanitizer resistance of Escherichia coli O157:H7 strains isolated from "high event period" meat contamination.

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    Wang, Rong; Kalchayanand, Norasak; King, David A; Luedtke, Brandon E; Bosilevac, Joseph M; Arthur, Terrance M

    2014-11-01

    In the meat industry, a "high event period" (HEP) is defined as a time period during which commercial meat plants experience a higher than usual rate of Escherichia coli O157:H7 contamination. Genetic analysis indicated that within a HEP, most of the E. coli O157:H7 strains belong to a singular dominant strain type. This was in disagreement with the current beef contamination model stating that contamination occurs when incoming pathogen load on animal hides, which consists of diverse strain types of E. coli O157:H7, exceeds the intervention capacity. Thus, we hypothesize that the HEP contam