Intestinimonas butyriciproducens gen. nov., sp. nov., a novel butyrate-producing bacterium from the mouse intestine

NARCIS (Netherlands)

Kläring, K.; Hanske, L.; Bui, T.P.N.; Charrier, C.; Blaut, M.; Haller, D.; Plugge, C.M.; Clavel, T.

2013-01-01

Whilst creating a bacterial collection of strains from the mouse intestine, we isolated a Gram-negative, spore-forming, non-motile and strictly anaerobic rod-shaped bacterium from the caecal content of a TNFdeltaARE mouse. The isolate, referred to as strain SRB-521-5-IT, was originally cultured on a

Gram-positive rods prevailing in teeth with apical periodontitis undergoing root canal treatment.

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Chávez de Paz, L E; Molander, A; Dahlén, G

2004-09-01

To identify Gram-positive rods from root canals of teeth with apical periodontitis and to examine their associations with other species. Consecutive root canal samples (RCSs) from 139 teeth undergoing root canal treatment were analyzed prospectively for cultivable microbes. Gram-positive rods in the first RCS submitted after chemo-mechanical preparation were categorised to genus level by selective media and gas-liquid chromatography (GLC), and identified to species level by sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE). Associations between organisms were measured by odds ratios (OR). In the first samples submitted a total of 158 Gram-positive rods, 115 Gram-positive cocci, 26 Gram-negative rods and 9 Gram-negative cocci, were identified. At genus levels Gram-positive rods were classified into: Lactobacillus spp. (38%), Olsenella spp. (18%), Propionibacterium spp. (13%), Actinomyces spp. (12%), Bifidobacterium spp. (13%) and Eubacterium spp. (6%). The most frequent species were Olsenella uli, Lactobacillus paracasei and Propionibacterium propionicum. In subsequent samples taken during treatment, Gram-positive rods were also identified, although the number of strains was considerably reduced. Positive associations were observed between members of the genus lactobacilli and Gram-positive cocci (OR>2). Olsenella uli and Lactobacillus spp. predominated over other Gram-positive rods. A possible association exists between Lactobacillus spp. and Gram-positive cocci in root canals of teeth with apical periodontitis receiving treatment.

Mechanism for longitudinal growth of rod-shaped bacteria

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Taneja, Swadhin; Levitan, Ben; Rutenberg, Andrew

2013-03-01

The peptidoglycan (PG) cell wall along with MreB proteins are major determinants of shape in rod-shaped bacteria. However the mechanism guiding the growth of this elastic network of cross-linked PG (sacculus) that maintains the integrity and shape of the rod-shaped cell remains elusive. We propose that the known anisotropic elasticity and anisotropic loading, due to the shape and turgor pressure, of the sacculus is sufficient to direct small gaps in the sacculus to elongate around the cell, and that subsequent repair leads to longitudinal growth without radial growth. We computationally show in our anisotropically stressed anisotropic elasticity model small gaps can extend stably in the circumferential direction for the known elasticity of the sacculus. We suggest that MreB patches that normally propagate circumferentially, are associated with these gaps and are steered with this common mechanism. This basic picture is unchanged in Gram positive and Gram negative bacteria. We also show that small changes of elastic properties can in fact lead to bi-stable propagation of gaps, both longitudinal and circumferential, that can explain the bi-stability in patch movement observed in ΔmblΔmreb mutants.

Formation and characterization of non-growth states in Clostridium thermocellum: spores and L-forms

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Mearls Elizabeth B

2012-08-01

Full Text Available Abstract Background Clostridium thermocellum is an anaerobic thermophilic bacterium that exhibits high levels of cellulose solublization and produces ethanol as an end product of its metabolism. Using cellulosic biomass as a feedstock for fuel production is an attractive prospect, however, growth arrest can negatively impact ethanol production by fermentative microorganisms such as C. thermocellum. Understanding conditions that lead to non-growth states in C. thermocellum can positively influence process design and culturing conditions in order to optimize ethanol production in an industrial setting. Results We report here that Clostridium thermocellum ATCC 27405 enters non-growth states in response to specific growth conditions. Non-growth states include the formation of spores and a L-form-like state in which the cells cease to grow or produce the normal end products of metabolism. Unlike other sporulating organisms, we did not observe sporulation of C. thermocellum in low carbon or nitrogen environments. However, sporulation did occur in response to transfers between soluble and insoluble substrates, resulting in approximately 7% mature spores. Exposure to oxygen caused a similar sporulation response. Starvation conditions during continuous culture did not result in spore formation, but caused the majority of cells to transition to a L-form state. Both spores and L-forms were determined to be viable. Spores exhibited enhanced survival in response to high temperature and prolonged storage compared to L-forms and vegetative cells. However, L-forms exhibited faster recovery compared to both spores and stationary phase cells when cultured in rich media. Conclusions Both spores and L-forms cease to produce ethanol, but provide other advantages for C. thermocellum including enhanced survival for spores and faster recovery for L-forms. Understanding the conditions that give rise to these two different non-growth states, and the implications that

Aliidiomarina haloalkalitolerans sp. nov., a marine bacterium isolated from coastal surface seawater

Digital Repository Service at National Institute of Oceanography (India)

Srinivas, T.N.R.; Nupur; AnilKumar, P.

A novel Gram-negative, rod shaped, motile, non-sporing strictly aerobic bacterium, designated strain AK5 sup(T), was isolated from a sea water sample collected near Visakhapatnam coast, Bay of Bengal, India. Colonies on marine agar were circular, 3...

Demequina lutea sp. nov., isolated from a high Arctic permafrost soil

DEFF Research Database (Denmark)

Finster, Kai; Herbert, Rodney Andrew; Kjeldsen, Kasper Urup

2009-01-01

Two Gram-stain-positive, pigmented, non-motile, non-spore-forming, pleomorphic, rod-shaped bacteria (strains SV45T and SV47), isolated from a permafrost soil collected from the Adventdalen valley, Spitsbergen, northern Norway, have been characterized taxonomically using a polyphasic approach...

LEVELS AND TYPES OF AEROBIC SPORE FORMING BACTERIA ...

African Journals Online (AJOL)

The four companies whose packaged product were studied had an average plate total spore counts as follows: Company A=6.2x 103; Company B= 3.1x 104; Company C= 6.0x 104 and Company D= 3.1x102 colony forming units per gram, respectively. Identification tests showed that among the aerobic spore formers were ...

Extended spectrum beta-lactamases in urinary gram-negative bacilli and their susceptibility pattern

International Nuclear Information System (INIS)

Mumtaz, S.

2008-01-01

Beta-lactamases of gram-negative bacteria are the most important mechanism of resistance against beta lactams. Two types of beta-lactamases can confer resistance against third generation cephalosporins inducible Chromosomal beta -lactamases and extended-spectrum beta-lactamases. The extended-spectrum beta lactamases producing Strains of Enterobacteriaceae have emerged as a major problem in hospitalized as well as community based infections resulting in range of infections from uncomplicated urinary tract infection to life threatening sepsis. The study was conducted at the Microbiology Department of Fauji Foundation Hospital, Rawalpindi over a period of two years (April 2004-March 2006). Multidrug resistance and extended spectrum beta-lactamases production was studied in 111 enteric Gram-negative bacilli isolated from urine of symptomatic patients (1- 70 years) including males and females from indoor and outdoor patients by using double disc diffusion technique. Prevalence of extended-spectrum beta-lactamases production was seen in 71 (61.2%) enteric gram-negative organisms, the most prevalent gram-negative organism was Klebsiella pneumoniae 40 (71.4%) followed by Escherichia coli 27 (62.8%) and Pseudomonas aeruginosa 3 (25%). The extended-spectrum beta-lactamases producers were more prevalent in indoor patients 63 (88.7%) compared to outdoor patients 8 (11.3%), more in females 43 (60.6%) than males, 28 (39.4%). The extended-spectrum beta-lactamases producing gram-negative rods had more antibiotic-resistant profile than non-producers. All enteric gram negative rods should be tested for the production of extended-spectrum beta-lactamases in routine microbiology laboratory. (author)

Characterization of the Lactobacillus isolated from different curd ...

African Journals Online (AJOL)

Lactic acid bacteria are commonly found in the fermented dairy products. Lactobacillus is a genus of lactic acid bacteria and described as heterogeneous group of regular, non-spore forming, gram-positive, rod shaped, non-motile bacteria and absence of catalase enzyme. The aim of this study was to isolate Lactobacillus ...

Use of Imipenem To Detect KPC, NDM, OXA, IMP, and VIM Carbapenemase Activity from Gram-Negative Rods in 75 Minutes Using Liquid Chromatography-Tandem Mass Spectrometry

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Kulkarni, M. V.; Zurita, A. N.; Pyka, J. S.; Murray, T. S.; Hodsdon, M. E.

2014-01-01

Resistance to extended-spectrum β-lactam antibiotics has led to a greater reliance upon carbapenems, but the expression of carbapenemases threatens to limit the utility of these drugs. Current methods to detect carbapenemase activity are suboptimal, requiring prolonged incubations during which ineffective therapy may be prescribed. We previously described a sensitive and specific assay for the detection of carbapenemase activity using ertapenem and liquid chromatography-tandem mass spectrometry (LC-MS/MS). In this study, we assessed 402 Gram-negative rods, including both Enterobacteriaceae and non-Enterobacteriaceae expressing IMP, VIM, KPC, NDM, and/or OXA carbapenemases, by using imipenem, meropenem, and ertapenem with LC-MS/MS assays. LC-MS/MS methods for the detection of intact and hydrolyzed carbapenems from an enrichment broth were developed. No ion suppression was observed, and the limits of detection for all three drugs were below 0.04 μg/ml. The sensitivity and specificity of meropenem and ertapenem for carbapenemase activity among non-Enterobacteriaceae were low, but imipenem demonstrated a sensitivity and specificity of 96% and 95%, respectively, among all Gram-negative rods (GNR) tested, including both Enterobacteriaceae and non-Enterobacteriaceae. LC-MS/MS allows for the analysis of more complex matrices, and this LC-MS/MS assay could easily be adapted for use with primary specimens requiring growth enrichment. PMID:24789180

The Causes of Post-Operative Meningitis: The Comparison Of Gram-Negative and Gram-Positive Pathogens.

Science.gov (United States)

Kurtaran, Behice; Kuscu, Ferit; Ulu, Aslihan; Inal, Ayse Seza; Komur, Suheyla; Kibar, Filiz; Cetinalp, Nuri Eralp; Ozsoy, Kerem Mazhar; Arslan, Yusuf Kemal; Aksu, Hasan Salih; Tasova, Yesim

2017-06-20

In this study, we aim to determine the microbiological etiology in critically ill neurosurgical patients with nosocomial meningitis (NM) and show the impact of Gram-negative rods and differences of patient's characteristics, clinical and prognostic measures between Gram-negative and Gram-positive meningitis. In this prospective, one center study we reviewed all adult patients hospitalized during a 12-year period and identified pathogens isolated from post-neurosurgical cases of NM. Demographic, clinical, and treatment characteristics were noted from the medical records. Of the 134 bacterial NM patients, 78 were male and 56 were female, with a mean age of 46±15.9 and median age of 50 (18-80) years. 141 strains isolated; 82 (58.2%) were Gram negative, 59 (41.8%) were Gram positive. Most common isolated microorganism was Acinetobacter baumannii (%34.8). In comparison of mortality data shows that the patients who have meningitis with Gram-negative pathogens have higher mortality than with Gram positives (p=0.034). The duration between surgery and meningitis was shorter in Gram negative meningitis cases compared to others (p=0.045) but the duration between the diagnosis and death was shorter in Gram-positive meningitis cases compared to Gram negatives (p= 0.017). CSF protein and lactate level were higher and glucose level was lower in cases of NM with Gram negatives (p value were respectively, 0.022, 0.039 and 0.049). As conclusions; in NM, Gram-negative pathogens were seen more frequently; A.baumanni was the predominant pathogen; and NM caused by Gram negatives had worse clinical and laboratory characteristic and prognostic outcome than Gram positives.

Activity of levofloxacin alone and in combination with a DnaK inhibitor against gram-negative rods, including levofloxacin-resistant strains.

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Credito, Kim; Lin, Gengrong; Koeth, Laura; Sturgess, Michael A; Appelbaum, Peter C

2009-02-01

Synergy time-kill testing of levofloxacin alone and in combination with CHP-105, a representative DnaK inhibitor, against 50 gram-negative rods demonstrated that 34 of the 50 strains tested showed significant synergy between levofloxacin and CHP-105 after 12 h and 24 h. Fourteen of these 34 organisms were quinolone resistant (levofloxacin MICs of > or =4 microg/ml).

Activity of Levofloxacin Alone and in Combination with a DnaK Inhibitor against Gram-Negative Rods, Including Levofloxacin-Resistant Strains▿

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Credito, Kim; Lin, Gengrong; Koeth, Laura; Sturgess, Michael A.; Appelbaum, Peter C.

2009-01-01

Synergy time-kill testing of levofloxacin alone and in combination with CHP-105, a representative DnaK inhibitor, against 50 gram-negative rods demonstrated that 34 of the 50 strains tested showed significant synergy between levofloxacin and CHP-105 after 12 h and 24 h. Fourteen of these 34 organisms were quinolone resistant (levofloxacin MICs of ≥4 μg/ml). PMID:19015359

Microbacter margulisiae gen. nov., sp. nov., a novel propionigenic bacterium isolated from sediments of an acid rock drainage pond

NARCIS (Netherlands)

Sanchez Andrea, I.; Luis Sanz, J.; Stams, A.J.M.

2014-01-01

A novel anaerobic propionigenic bacterium, strain ADRIT, was isolated from sediment of an acid rock drainage environment (Tinto River, Spain). Cells were small (0.4-0.6 x 1-1.7 µm), non-motile and non-spore forming rods. Cells possessed a Gram-negative cell wall structure and were vancomycin

Update on the taxonomy and the clinical and laboratory characteristics of pigmented anaerobic gram-negative rods.

Science.gov (United States)

Jousimies-Somer, H R

1995-06-01

Pigmented anaerobic gram-negative rods are currently categorized as 17 species distributed in three genera: Prevotella, Porphyromonas, and Bacteroides. These organisms are often encountered in clinical specimens but are also found as part of the indigenous flora on various mucosal surfaces. Several studies are presently assessing the association of individual species with health and disease. For example, Porphyromonas gingivalis and Porphyromonas endodontalis are key putative pathogens in adult periodontitis and root canal infections, respectively. Porphyromonas asaccharolytica is prevalent in extraoral infections. The Porphyromonas species of animal origin have been isolated from infected bite wounds in humans. Isolates closely resembling Bacteroides levii have been recovered from various types of human infections. According to preliminary reports, Prevotella intermedia tends to be associated more often with periodontal disease than with a healthy oral cavity. In the laboratory, enzyme profiling facilitates the identification of these pigmented rods. Beta-Lactamase production is more common among prevotella species (30%-50%) than among Porphyromonas species (< 10%).

How bacterial cell division might cheat turgor pressure - a unified mechanism of septal division in Gram-positive and Gram-negative bacteria.

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Erickson, Harold P

2017-08-01

An important question for bacterial cell division is how the invaginating septum can overcome the turgor force generated by the high osmolarity of the cytoplasm. I suggest that it may not need to. Several studies in Gram-negative bacteria have shown that the periplasm is isoosmolar with the cytoplasm. Indirect evidence suggests that this is also true for Gram-positive bacteria. In this case the invagination of the septum takes place within the uniformly high osmotic pressure environment, and does not have to fight turgor pressure. A related question is how the V-shaped constriction of Gram-negative bacteria relates to the plate-like septum of Gram-positive bacteria. I collected evidence that Gram-negative bacteria have a latent capability of forming plate-like septa, and present a model in which septal division is the basic mechanism in both Gram-positive and Gram-negative bacteria. © 2017 WILEY Periodicals, Inc.

Carbapenem-Resistant Non-Glucose-Fermenting Gram-Negative Bacilli: the Missing Piece to the Puzzle

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Gniadek, Thomas J.; Carroll, Karen C.

2016-01-01

The non-glucose-fermenting Gram-negative bacilli Pseudomonas aeruginosa and Acinetobacter baumannii are increasingly acquiring carbapenem resistance. Given their intrinsic antibiotic resistance, this can cause extremely difficult-to-treat infections. Additionally, resistance gene transfer can occur between Gram-negative species, regardless of their ability to ferment glucose. Thus, the acquisition of carbapenemase genes by these organisms increases the risk of carbapenemase spread in general. Ultimately, infection control practitioners and clinical microbiologists need to work together to determine the risk carried by carbapenem-resistant non-glucose-fermenting Gram-negative bacilli (CR-NF) in their institution and what methods should be considered for surveillance and detection of CR-NF. PMID:26912753

High-quality permanent draft genome sequence of the Bradyrhizobium elkanii type strain USDA 76T, isolated from Glycine max (L.) Merr

Science.gov (United States)

Bradyrhizobium elkanii USDA 76T (INSCD = ARAG00000000), the type strain for Bradyrhizobium elkanii, is an aerobic, motile, Gram-negative, non-spore-forming rod that was isolated from an effective nitrogen-fixing root nodule of Glycine max (L. Merr) grown in the USA. Because of its significance as a ...

Evaluation of pyrrolidonyl arylamidase for the identification of nonfermenting Gram-negative rods.

Science.gov (United States)

Bombicino, Karina A; Almuzara, Marisa N; Famiglietti, Angela M R; Vay, Carlos

2007-01-01

To evaluate the activity of pyrrolidonyl arylamidase (PYR) for the differentiation and identification of nonfermenting gram negative rods (NFGNR), 293 isolates were tested. A 24 h culture of each test organism was prepared. From this a 108-109 cfu/mL suspension was added to 0.25 mL of sterile physiologic solution. A PYR disk was then added and the test was incubated for 30 minutes at 35-37 degrees C, at environmental atmosphere. Reading was done by adding 1 drop of cinnamaldehyde reagent. Strains of Acinetobacter baumannii, Acinetobacter haemolyticus, Alcaligenes faecalis, Bergeyella zoohelcum, Bordetella bronchiseptica, Bordetella hinzii, Brevundimonas diminuta, Brevundimonas vesicularis, Brucella ovis, Brucella spp., Brucella suis, Burkholderia cepacia complex, Moraxella catarrhalis, Moraxella lacunata, Moraxella nonliquefaciens, Moraxella osloensis, Oligella ureolytica, Pseudomonas alcaligenes, Pseudomonas mendocina, Pseudomonas pseudoalcaligenes, Pseudomonas putida, Pseudomonas stutzeri, Pseudomonas Vb3, Psychrobacter phenylpyruvicus, and Stenotrophomonas maltophilia were PYR negative. On the other hand Achromobacter piechaudii, Achromobacter denitrificans, Achromobacter xylosoxidans, Burkholderia gladioli, Chryseobacterium gleum-indologenes, Comamonas testosroni, Cupriavidus pauculus, Delftia acidovorans, Elizabethkingia meningoseptica, Myroides spp., Ochrobactrum anthropi, Pseudomonas oryzihabitans, Ralstonia pickettii, Rhizobium radiobacter, Shewanella spp., Sphingobacterium multivorum, Sphingobacterium spiritivorum, and Weeksella virosa were PYR positive. Finally, Acinetobacter lwoffii, Pseudomonas aeruginosa, Pseudomonas fluorescens, Roseomonas spp., and Sphingomonas paucimobilis-parapaucimobilis were PYR variable. PYR testing should be considered as a useful tool to facilitate the identification of NFGNR.

Screening of the novel colicinogenic gram-negative rods against pathogenic Escherichia coli O157:H7

Directory of Open Access Journals (Sweden)

H Mushtaq

2015-01-01

Full Text Available Purpose: Escherichia coli (E. coli O157:H7 is gram-negative enteric pathogen producing different types of Shiga toxin. This bacterium is the most corporate cause of haemorrhagic colitis in human. Administration of antibiotics (particularly sulfa drugs against this pathogen is a debatable topic as this may increase the risk of uremic syndrome; especially in children and aged people. Around the world, microbiologists are in search of alternative therapeutic methods specially probiotics against this pathogen. In the present study, we have focused on the investigation of alternate bio-therapeutics (probiotics for the treatment of patients infected with E. coli O157:H7. This study is based on the identification of colicin-producing gram-negative bacteria (particularly enterobacteriaceae which can competently exclude E. coli O157:H7 from the gut of the infected individual. Materials and Methods: Hundred samples from human, animal faeces and septic tank water were analysed for nonpathogenic gram-negative rods (GNRs. Results: Out of these samples, 175 isolates of GNRs were checked for their activity against E. coli O157:H7. Only 47 isolates inhibited the growth of E. coli O157:H7, among which majority were identified as E. coli. These E. coli strains were found to be the efficient producers of colicin. Some of the closely related species i. e., Citrobacter sp, Pantoea sp. and Kluyvera sp. also showed considerable colicinogenic activity. Moreover, colicinogenic species were found to be nonhaemolytic, tolerant to acidic environment (pH 3 and sensitive to commonly used antibiotics. Conclusion: Nonhaemolytic, acid tolerant and sensitive to antibiotics suggests the possible use of these circulating endothelial cells (CEC as inexpensive and inoffensive therapeutic agent (probiotics in E. coli O157:H7 infections.

The Carbapenem Inactivation Method (CIM), a Simple and Low-Cost Alternative for the Carba NP Test to Assess Phenotypic Carbapenemase Activity in Gram-Negative Rods

NARCIS (Netherlands)

Zwaluw, K. van der; Haan, A. de; Pluister, G.N.; Bootsma, H.J.; Neeling, A.J. de; Schouls, L.M.

2015-01-01

A new phenotypic test, called the Carbapenem Inactivation Method (CIM), was developed to detect carbapenemase activity in Gram-negative rods within eight hours. This method showed high concordance with results obtained by PCR to detect genes coding for the carbapenemases KPC, NDM, OXA-48, VIM, IMP

Long-term cryopreservation of non-spore-forming fungi in Microbank™ beads for plant pathological investigations.

Science.gov (United States)

Lakshman, Dilip K; Singh, Vimla; Camacho, Manuel E

2018-05-01

Long-term preservation of experimental fungi without genetic, morphological, and pathogenic changes is of paramount importance in mycological and plant pathological investigations. Several cryogenic and non-cryogenic methods are available for the preservation of fungi, but the methods can be cumbersome, hazardous, expensive, and often not suitable for long-term storage of non-spore-forming (sterile) fungi. A method of preservation of spore-forming fungi in commercially available porous beads (Micrbank™) under cryogenic condition was successfully tested for three non-spore-forming basidiomycetes genera: Rhizoctonia solani (teleomorph: Thanatephorus cucumeris) (n = 19), Ceratobasidium species (n = 1), and Waitea circinata (n = 3), and a non-spore forming ascomycetes, Sclerotinia sclerotiorum (n = 1). For comparison, spore-forming ascomycetous fungi, Alternaria alternata (n = 1), Bauveria basiana (n = 2), Botrytis cinerea (n = 1), Fusarium oxysporum f.sp. gladiolii (n = 1), Trichoderma spp. (n = 3), and Thielaviopsis basicola (n = 2) were also cryopreserved in Microbank beads. Viable fungal isolates of all test species were retrieved after five years of storage at -80 °C, which was longer than the viabilities of the corresponding isolates cryopreserved in agar plugs or colonized wheat seeds. Fungi revived from the Microbank beads maintained identical morphology and cultural characteristics of the parent isolates. Randomly selected Rhizoctonia isolates revived from the Microbank beads maintained respective pathological properties of the parent isolates; also, no mutation was detected in the internal transcribed spacer (ITS) ribosomal DNA when compared with respective cultures maintained at ambient temperature. This finding demonstrated the utility of cryopreservation in Microbank beads as a convenient alternative to conventional long-term preservation of a wide group of fungal cultures for plant pathological investigations

Probing interaction of Gram-positive and Gram-negative bacterial cells with ZnO nanorods

Energy Technology Data Exchange (ETDEWEB)

Jain, Aanchal; Bhargava, Richa; Poddar, Pankaj, E-mail: p.poddar@ncl.res.in

2013-04-01

In the present work, the physiological effects of the ZnO nanorods on the Gram positive (Staphylococcus aureus and Bacillus subtilis) and Gram-negative (Escherichia coli and Aerobacter aerogenes) bacterial cells have been studied. The analysis of bacterial growth curves for various concentrations of ZnO nanorods indicates that Gram positive and Gram negative bacterial cells show inhibition at concentrations of ∼ 64 and ∼ 256 μg/mL respectively. The marked difference in susceptibility towards nanorods was also validated by spread plate and disk diffusion methods. In addition, the scanning electron micrographs show a clear damage to the cells via changed morphology of the cells from rod to coccoid etc. The confocal optical microscopy images of these cells also demonstrate the reduction in live cell count in the presence of ZnO nanorods. These, results clearly indicate that the antibacterial activity of ZnO nanorods is higher towards Gram positive bacterium than Gram negative bacterium which indicates that the structure of the cell wall might play a major role in the interaction with nanostructured materials and shows high sensitivity to the particle concentration. Highlights: ► Effect of ZnO nanorods on the growth cycles of four bacterial strains. ► A relation has been established between growth rate of bacteria and concentration. ► Serious damage in the morphology of bacterial cells in the presence of ZnO nanorods. ► Microscopic studies to see the time dependent effect on bacterial cells.

Discrimination of Spore-Forming Bacilli Using spoIVA

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Venkateswaran, Kasthuri; LaDuc, Myron; Stuecker, Tara

2009-01-01

A method of discriminating between spore-forming and non-spore-forming bacteria is based on a combination of simultaneous sporulation-specific and non-sporulation-specific quantitative polymerase chain reactions (Q-PCRs). The method was invented partly in response to the observation that for the purposes of preventing or reducing biological contamination affecting many human endeavors, ultimately, only the spore-forming portions of bacterial populations are the ones that are problematic (or, at least, more problematic than are the non-spore-forming portions). In some environments, spore-forming bacteria constitute small fractions of the total bacterial populations. The use of sporulation-specific primers in Q-PCR affords the ability to assess the spore-forming fraction of a bacterial population present in an environment of interest. This assessment can provide a more thorough and accurate understanding of the bacterial contamination in the environment, thereby making it possible to focus contamination- testing, contamination-prevention, sterilization, and decontamination resources more economically and efficiently. The method includes the use of sporulation-specific primers in the form of designed, optimized deoxyribonucleic acid (DNA) oligonucleotides specific for the bacterial spoIVA gene (see table). [In "spoIVA," "IV" signifies Roman numeral four and the entire quoted name refers to gene A for the fourth stage of sporulation.] These primers are mixed into a PCR cocktail with a given sample of bacterial cells. A control PCR cocktail into which are mixed universal 16S rRNA primers is also prepared. ["16S rRNA" denotes a ribosomal ribonucleic acid (rRNA) sequence that is common to all organisms.] Following several cycles of heating and cooling according to the PCR protocol to amplify amounts of DNA molecules, the amplification products can be analyzed to determine the types of bacterial cells present within the samples. If the amplification product is strong

Evaluation of gram-chromotrope kinyoun staining technique: its effectiveness in detecting microsporidial spores in fecal specimens.

Science.gov (United States)

Salleh, Fatmah M; Al-Mekhlafi, Abdulsalam M; Nordin, Anisah; Yasin, 'Azlin M; Al-Mekhlafi, Hesham M; Moktar, Norhayati

2011-01-01

This study was conducted to evaluate the modification of the usual Gram-chromotrope staining technique developed in-house known as Gram-chromotrope Kinyoun (GCK) in comparison with the Weber Modified Trichrome (WMT) staining technique; as the reference technique. Two hundred and ninety fecal specimens received by the Microbiology Diagnostic Laboratory of Hospital Universiti Kebangsaan Malaysia were examined for the presence of microsporidial spores. The sensitivity and specificity of GCK compared to the reference technique were 98% and 98.3%, respectively. The positive and negative predictive values were 92.5% and 99.6%, respectively. The agreement between the reference technique and the GCK staining technique was statistically significant by Kappa statistics (K = 0.941, P staining technique has high sensitivity and specificity in the detection of microsporidial spores in fecal specimens. Hence, it is recommended to be used in the diagnosis of intestinal microsporidiosis. Copyright © 2011 Elsevier Inc. All rights reserved.

Gram staining for the treatment of peritonsillar abscess.

Science.gov (United States)

Takenaka, Yukinori; Takeda, Kazuya; Yoshii, Tadashi; Hashimoto, Michiko; Inohara, Hidenori

2012-01-01

Objective. To examine whether Gram staining can influence the choice of antibiotic for the treatment of peritonsillar abscess. Methods. Between 2005 and 2009, a total of 57 cases of peritonsillar abscess were analyzed with regard to cultured bacteria and Gram staining. Results. Only aerobes were cultured in 16% of cases, and only anaerobes were cultured in 51% of cases. Mixed growth of aerobes and anaerobes was observed in 21% of cases. The cultured bacteria were mainly aerobic Streptococcus, anaerobic Gram-positive cocci, and anaerobic Gram-negative rods. Phagocytosis of bacteria on Gram staining was observed in 9 cases. The bacteria cultured from these cases were aerobic Streptococcus, anaerobic Gram-positive cocci, and anaerobic Gram-negative rods. The sensitivity of Gram staining for the Gram-positive cocci and Gram-negative rods was 90% and 64%, respectively. The specificity of Gram staining for the Gram-positive cocci and Gram-negative rods was 62% and 76%, respectively. Most of the Gram-positive cocci were sensitive to penicillin, but some of anaerobic Gram-negative rods were resistant to penicillin. Conclusion. When Gram staining shows only Gram-positive cocci, penicillin is the treatment of choice. In other cases, antibiotics effective for the penicillin-resistant organisms should be used.

The structural bases of long-term anabiosis in non-spore-forming bacteria

Science.gov (United States)

Suzina, Natalia E.; Mulyukin, Andrey L.; Dmitriev, Vladimir V.; Nikolaev, Yury A.; Shorokhova, Anna P.; Bobkova, Yulia S.; Barinova, Ekaterina S.; Plakunov, Vladimir K.; El-Registan, Galina I.; Duda, Vitalii I.

2006-01-01

Peculiarities of the structural organization in non-spore-forming bacteria associated with long-term anabiosis were revealed both in laboratory cultures and in natural populations isolated from 1 3-Myr-old Eastern Siberian permafrost and tundra soil. Different advanced methods were used, including (a) high-resolution electron microscopy; (b) simulation of in situ conditions in the laboratory by varying the composition of growth medium and cultivation conditions; (c) low-temperature fractionation to isolate and concentrate microbial cells from natural soils; (d) comparative morphological analysis of microbial cells in model cultures and natural soils (in situ). Under laboratory conditions, the intense formation of resting cells by representatives of various taxa of eubacteria and halophilic archaea occurred in 2 9-month-old cultures grown in carbon-, nitrogen-, or phosphorus-limited media, in starved cell suspensions in the presence of sodium silicate, or on soil agar. Among resting cells, we revealed cystlike forms having a complicated structure and common features. These included a thick capsule; a thickened and multiprofile cell wall; the presence of large intramembrane particles on PF- and EF-fracture surfaces; fine-grained or lumpy cytoplasm; and a condensed nucleoid. The general morphological properties, ultrastructural organization, physiological features of cystlike cells, and their ability to germinate under the appropriate conditions suggest the existence of constitutive dormancy in non-spore-forming bacteria. It was found that the majority of microorganisms in permafrost and tundra soil are cystlike cells, very similar to those in laboratory cultures. Anabiotic (resting) cystlike cells are responsible for the survival of non-spore-formers in extreme Earth habitats and may be regarded as possible analogs of extraterrestrial forms of microbial life.

Fermentative Degradation of Polyethylene Glycol by a Strictly Anaerobic, Gram-Negative, Nonsporeforming Bacterium, Pelobacter venetianus sp. nov

OpenAIRE

1983-01-01

The synthetic polyether polyethylene glycol (PEG) with a molecular weight of 20,000 was anaerobically degraded in enrichment cultures inoculated with mud of limnic and marine origins. Three strains (Gra PEG 1, Gra PEG 2, and Ko PEG 2) of rod-shaped, gram-negative, nonsporeforming, strictly anaerobic bacteria were isolated in mineral medium with PEG as the sole source of carbon and energy. All strains degraded dimers, oligomers, and polymers of PEG up to a molecular weight of 20,000 completely...

Cell wall elongation mode in Gram-negative bacteria is determined by peptidoglycan architecture.

Science.gov (United States)

Turner, Robert D; Hurd, Alexander F; Cadby, Ashley; Hobbs, Jamie K; Foster, Simon J

2013-01-01

Cellular integrity and morphology of most bacteria is maintained by cell wall peptidoglycan, the target of antibiotics essential in modern healthcare. It consists of glycan strands, cross-linked by peptides, whose arrangement determines cell shape, prevents lysis due to turgor pressure and yet remains dynamic to allow insertion of new material, and hence growth. The cellular architecture and insertion pattern of peptidoglycan have remained elusive. Here we determine the peptidoglycan architecture and dynamics during growth in rod-shaped Gram-negative bacteria. Peptidoglycan is made up of circumferentially oriented bands of material interspersed with a more porous network. Super-resolution fluorescence microscopy reveals an unexpected discontinuous, patchy synthesis pattern. We present a consolidated model of growth via architecture-regulated insertion, where we propose only the more porous regions of the peptidoglycan network that are permissive for synthesis.

Differential staining of bacteria: gram stain.

Science.gov (United States)

Moyes, Rita B; Reynolds, Jackie; Breakwell, Donald P

2009-11-01

In 1884, Hans Christian Gram, a Danish doctor, developed a differential staining technique that is still the cornerstone of bacterial identification and taxonomic division. This multistep, sequential staining protocol separates bacteria into four groups based on cell morphology and cell wall structure: Gram-positive cocci, Gram-negative cocci, Gram-positive rods, and Gram-negative rods. The Gram stain is useful for assessing bacterial contamination of tissue culture samples or for examining the Gram stain status and morphological features of bacteria isolated from mixed or isolated bacterial cultures. (c) 2009 by John Wiley & Sons, Inc.

Structure, diversity and evolution of protein toxins from spore-forming entomopathogenic bacteria

NARCIS (Netherlands)

Maagd, de R.A.; Bravo, A.; Berry, C.; Crickmore, N.; Schnepf, H.E.

2003-01-01

Gram-positive spore-forming entomopathogenic bacteria can utilize a large variety of protein toxins to help them invade, infect, and finally kill their hosts, through their action on the insect midgut. These toxins belong to a number of homology groups containing a diversity of protein structures

Prognostic factors and monomicrobial necrotizing fasciitis: gram-positive versus gram-negative pathogens

Directory of Open Access Journals (Sweden)

Hsu Wei-Hsiu

2011-01-01

Full Text Available Abstract Background Monomicrobial necrotizing fasciitis is rapidly progressive and life-threatening. This study was undertaken to ascertain whether the clinical presentation and outcome for patients with this disease differ for those infected with a gram-positive as compared to gram-negative pathogen. Methods Forty-six patients with monomicrobial necrotizing fasciitis were examined retrospectively from November 2002 to January 2008. All patients received adequate broad-spectrum antibiotic therapy, aggressive resuscitation, prompt radical debridement and adjuvant hyperbaric oxygen therapy. Eleven patients were infected with a gram-positive pathogen (Group 1 and 35 patients with a gram-negative pathogen (Group 2. Results Group 2 was characterized by a higher incidence of hemorrhagic bullae and septic shock, higher APACHE II scores at 24 h post-admission, a higher rate of thrombocytopenia, and a higher prevalence of chronic liver dysfunction. Gouty arthritis was more prevalent in Group 1. For non-survivors, the incidences of chronic liver dysfunction, chronic renal failure and thrombocytopenia were higher in comparison with those for survivors. Lower level of serum albumin was also demonstrated in the non-survivors as compared to those in survivors. Conclusions Pre-existing chronic liver dysfunction, chronic renal failure, thrombocytopenia and hypoalbuminemia, and post-operative dependence on mechanical ventilation represent poor prognostic factors in monomicrobial necrotizing fasciitis. Patients with gram-negative monobacterial necrotizing fasciitis present with more fulminant sepsis.

A Clostridium difficile-Specific, Gel-Forming Protein Required for Optimal Spore Germination

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M. Lauren Donnelly

2017-01-01

Full Text Available Clostridium difficile is a Gram-positive spore-forming obligate anaerobe that is a leading cause of antibiotic-associated diarrhea worldwide. In order for C. difficile to initiate infection, its aerotolerant spore form must germinate in the gut of mammalian hosts. While almost all spore-forming organisms use transmembrane germinant receptors to trigger germination, C. difficile uses the pseudoprotease CspC to sense bile salt germinants. CspC activates the related subtilisin-like protease CspB, which then proteolytically activates the cortex hydrolase SleC. Activated SleC degrades the protective spore cortex layer, a step that is essential for germination to proceed. Since CspC incorporation into spores also depends on CspA, a related pseudoprotease domain, Csp family proteins play a critical role in germination. However, how Csps are incorporated into spores remains unknown. In this study, we demonstrate that incorporation of the CspC, CspB, and CspA germination regulators into spores depends on CD0311 (renamed GerG, a previously uncharacterized hypothetical protein. The reduced levels of Csps in gerG spores correlate with reduced responsiveness to bile salt germinants and increased germination heterogeneity in single-spore germination assays. Interestingly, asparagine-rich repeat sequences in GerG’s central region facilitate spontaneous gel formation in vitro even though they are dispensable for GerG-mediated control of germination. Since GerG is found exclusively in C. difficile, our results suggest that exploiting GerG function could represent a promising avenue for developing C. difficile-specific anti-infective therapies.

Gelria glutamica gen. nov., sp. a thermophilic oligately syntrophic glutamate-degrading anaerobe

NARCIS (Netherlands)

Plugge, C.M.; Balk, M.; Zoetendal, E.G.; Stams, A.J.M.

2002-01-01

A novel anaerobic, Gram-positive, thermophilic, spore-forming, obligately syntrophic, glutamate-degrading bacterium, strain TGO(T), was isolated from a propionate-oxidizing methanogenic enrichment culture. The axenic culture was obtained by growing the bacterium on pyruvate. Cells were rod-shaped

Handling technique of spore-forming bacteria in radiation sterilization. 1. Preparation of spores

International Nuclear Information System (INIS)

Koshikawa, Tomihiko

1994-01-01

This paper deals with a handling technique of spore-forming bacteria in radiation sterilization. An explanation is given under three sections: (1) life cycle of spore-forming bacteria, medium to form bacterial spores, and colony and purification methods of bacterial spores; (2) methods for measuring the number of bacterial spores and resistance against gamma radiation (D values); and (3) a test method for identifying spore-forming bacteria and a simple identification method. (N.K.)

Antimicrobial Photodynamic Therapy to Kill Gram-negative Bacteria

Science.gov (United States)

Sperandio, Felipe F; Huang, Ying-Ying; Hamblin, Michael R

2013-01-01

Antimicrobial photodynamic therapy (PDT) or photodynamic inactivation (PDI) is a new promising strategy to eradicate pathogenic microorganisms such as Gram-positive and Gram-negative bacteria, yeasts and fungi. The search for new approaches that can kill bacteria but do not induce the appearance of undesired drug-resistant strains suggests that PDT may have advantages over traditional antibiotic therapy. PDT is a non-thermal photochemical reaction that involves the simultaneous presence of visible light, oxygen and a dye or photosensitizer (PS). Several PS have been studied for their ability to bind to bacteria and efficiently generate reactive oxygen species (ROS) upon photostimulation. ROS are formed through type I or II mechanisms and may inactivate several classes of microbial cells including Gram-negative bacteria such as Pseudomonas aeruginosa, which are typically characterized by an impermeable outer cell membrane that contains endotoxins and blocks antibiotics, dyes, and detergents, protecting the sensitive inner membrane and cell wall. This review covers significant peer-reviewed articles together with US and World patents that were filed within the past few years and that relate to the eradication of Gram-negative bacteria via PDI or PDT. It is organized mainly according to the nature of the PS involved and includes natural or synthetic food dyes; cationic dyes such as methylene blue and toluidine blue; tetrapyrrole derivatives such as phthalocyanines, chlorins, porphyrins, chlorophyll and bacteriochlorophyll derivatives; functionalized fullerenes; nanoparticles combined with different PS; other formulations designed to target PS to bacteria; photoactive materials and surfaces; conjugates between PS and polycationic polymers or antibodies; and permeabilizing agents such as EDTA, PMNP and CaCl2. The present review also covers the different laboratory animal models normally used to treat Gram-negative bacterial infections with antimicrobial PDT. PMID

Insights into the extremotolerance of Acinetobacter radioresistens 50v1, a gram-negative bacterium isolated from the Mars Odyssey spacecraft.

Science.gov (United States)

McCoy, K B; Derecho, I; Wong, T; Tran, H M; Huynh, T D; La Duc, M T; Venkateswaran, K; Mogul, R

2012-09-01

The microbiology of the spacecraft assembly process is of paramount importance to planetary exploration, as the biological contamination that can result from remote-enabled spacecraft carries the potential to impact both life-detection experiments and extraterrestrial evolution. Accordingly, insights into the mechanisms and range of extremotolerance of Acinetobacter radioresistens 50v1, a Gram-negative bacterium isolated from the surface of the preflight Mars Odyssey orbiter, were gained by using a combination of microbiological, enzymatic, and proteomic methods. In summary, A. radioresistens 50v1 displayed a remarkable range of survival against hydrogen peroxide and the sequential exposures of desiccation, vapor and plasma phase hydrogen peroxide, and ultraviolet irradiation. The survival is among the highest reported for non-spore-forming and Gram-negative bacteria and is based upon contributions from the enzyme-based degradation of H(2)O(2) (catalase and alkyl hydroperoxide reductase), energy management (ATP synthase and alcohol dehydrogenase), and modulation of the membrane composition. Together, the biochemical and survival features of A. radioresistens 50v1 support a potential persistence on Mars (given an unintended or planned surface landing of the Mars Odyssey orbiter), which in turn may compromise the scientific integrity of future life-detection missions.

Antimicrobial-resistant Gram-negative bacteria in febrile neutropenic patients with cancer: current epidemiology and clinical impact.

Science.gov (United States)

Trecarichi, Enrico M; Tumbarello, Mario

2014-04-01

In the recent years, several studies involving cancer patients have demonstrated a clear trend in the epidemiology of bacterial infections showing a shift in the prevalence from Gram-positive to Gram-negative bacteria and the extensive emergence of antimicrobial-resistant strains among Gram-negatives isolated from the blood. The aim of this systematic review was to examine the recent trends in epidemiology and antimicrobial resistance in Gram-negatives recovered from neutropenic cancer patients, with particular emphasis on the impact of antimicrobial resistance on the clinical outcome of severe infections caused by such microorganisms. Overall, from 2007 to date, the rate of Gram-negative bacteria recovery ranged from 24.7 to 75.8% (mean 51.3%) in cancer patient cohorts. Escherichia coli represented the most common species (mean frequency of isolation 32.1%) among the Gram-negatives, followed by Pseudomonas aeruginosa (mean frequency of isolation 20.1%). An increasing frequency of Acinetobacter spp. and Stenotrophomonas maltophilia was also reported. Increased rates of multidrug-resistant Gram-negative strains have been highlighted among Enterobacteriaceae and nonfermenting Gram-negative rods, despite discontinuation of fluoroquinolone-based antibacterial prophylaxis for neutropenic patients. In addition, antimicrobial resistance and/or the inadequacy of empirical antibiotic treatment have been frequently linked to a worse outcome in cancer patients with bloodstream infections caused by Gram-negative isolates. Sound knowledge of the local distribution of pathogens and their susceptibility patterns and prompt initiation of effective antimicrobial treatment for severe infections caused by Gram-negative bacteria are essential in cancer patients.

Procalcitonin levels in gram-positive, gram-negative, and fungal bloodstream infections.

Science.gov (United States)

Leli, Christian; Ferranti, Marta; Moretti, Amedeo; Al Dhahab, Zainab Salim; Cenci, Elio; Mencacci, Antonella

2015-01-01

Procalcitonin (PCT) can discriminate bacterial from viral systemic infections and true bacteremia from contaminated blood cultures. The aim of this study was to evaluate PCT diagnostic accuracy in discriminating Gram-positive, Gram-negative, and fungal bloodstream infections. A total of 1,949 samples from patients with suspected bloodstream infections were included in the study. Median PCT value in Gram-negative (13.8 ng/mL, interquartile range (IQR) 3.4-44.1) bacteremias was significantly higher than in Gram-positive (2.1 ng/mL, IQR 0.6-7.6) or fungal (0.5 ng/mL, IQR 0.4-1) infections (P Gram-negatives from Gram-positives at the best cut-off value of 10.8 ng/mL and an AUC of 0.944 (95% CI 0.919-0.969, P Gram-negatives from fungi at the best cut-off of 1.6 ng/mL. Additional results showed a significant difference in median PCT values between Enterobacteriaceae and nonfermentative Gram-negative bacteria (17.1 ng/mL, IQR 5.9-48.5 versus 3.5 ng/mL, IQR 0.8-21.5; P Gram-negative from Gram-positive and fungal bloodstream infections. Nevertheless, its utility to predict different microorganisms needs to be assessed in further studies.

Dustborne and airborne gram-positive and gram-negative bacteria in high versus low ERMI homes

Science.gov (United States)

The study aimed at investigating Gram-positive and Gram-negative bacteria in moldy and non-moldy homes, as defined by the home's Environmental Relative Moldiness Index (ERMI) value. The ERMI values were determined from floor dust samples in 2010 and 2011 and homes were classified...

An optimized staining technique for the detection of Gram positive and Gram negative bacteria within tissue.

Science.gov (United States)

Becerra, Sandra C; Roy, Daniel C; Sanchez, Carlos J; Christy, Robert J; Burmeister, David M

2016-04-12

Bacterial infections are a common clinical problem in both acute and chronic wounds. With growing concerns over antibiotic resistance, treatment of bacterial infections should only occur after positive diagnosis. Currently, diagnosis is delayed due to lengthy culturing methods which may also fail to identify the presence of bacteria. While newer costly bacterial identification methods are being explored, a simple and inexpensive diagnostic tool would aid in immediate and accurate treatments for bacterial infections. Histologically, hematoxylin and eosin (H&E) and Gram stains have been employed, but are far from optimal when analyzing tissue samples due to non-specific staining. The goal of the current study was to develop a modification of the Gram stain that enhances the contrast between bacteria and host tissue. A modified Gram stain was developed and tested as an alternative to Gram stain that improves the contrast between Gram positive bacteria, Gram negative bacteria and host tissue. Initially, clinically relevant strains of Pseudomonas aeruginosa and Staphylococcus aureus were visualized in vitro and in biopsies of infected, porcine burns using routine Gram stain, and immunohistochemistry techniques involving bacterial strain-specific fluorescent antibodies as validation tools. H&E and Gram stain of serial biopsy sections were then compared to a modification of the Gram stain incorporating a counterstain that highlights collagen found in tissue. The modified Gram stain clearly identified both Gram positive and Gram negative bacteria, and when compared to H&E or Gram stain alone provided excellent contrast between bacteria and non-viable burn eschar. Moreover, when applied to surgical biopsies from patients that underwent burn debridement this technique was able to clearly detect bacterial morphology within host tissue. We describe a modification of the Gram stain that provides improved contrast of Gram positive and Gram negative microorganisms within host

Detection and Antibiotic Susceptibility Pattern of Biofilm Producing Gram Positive and Gram Negative Bacteria Isolated From a Tertiary Care Hospital of Pakistan

Directory of Open Access Journals (Sweden)

Iqbal, M.

2011-01-01

Full Text Available Microorganisms adhere to non-living material or living tissue, and form biofilms made up of extracellular polymers/slime. Biofilm-associated microorganisms behave differently from free-floating bacteria with respect to growth rates and ability to resist antimicrobial treatments and therefore pose a public health problem. The objective of this study is to detect the prevalence of biofilm producers among Gram positive and Gram negative bacteria isolated from clinical specimens, and to study their antimicrobial susceptibility pattern. The study was carried out from October 2009 to March 2010, at the Department of Microbiology, Army Medical College/ National University of Sciences and Technology (NUST, Rawalpindi, Pakistan. Clinical specimens were received from various wards of a tertiary care hospital. These were dealt by standard microbiological procedures. Gram positive and Gram negative bacteria isolated were subjected to biofilm detection by congo red agar method (CRA. Antimicrobial susceptibility testing of those isolates, which showed positive results (slime production, was done according to the Kirby-Bauer disc diffusion technique. A total of 150 isolates were tested for the production of biofilm/slime. Among them, 81 isolates showed positive results. From these 81, 51 were Gram positive and 30 were Gram negative. All the 81(54% slime producers showed reduced susceptibility to majority of antibiotics. Bacterial biofilms are an important virulence factor associated with chronic nosocomial infection. Detection of biofilm forming organisms can help in appropriate antibiotic choice.

Procalcitonin Levels in Gram-Positive, Gram-Negative, and Fungal Bloodstream Infections

Directory of Open Access Journals (Sweden)

Christian Leli

2015-01-01

Full Text Available Procalcitonin (PCT can discriminate bacterial from viral systemic infections and true bacteremia from contaminated blood cultures. The aim of this study was to evaluate PCT diagnostic accuracy in discriminating Gram-positive, Gram-negative, and fungal bloodstream infections. A total of 1,949 samples from patients with suspected bloodstream infections were included in the study. Median PCT value in Gram-negative (13.8 ng/mL, interquartile range (IQR 3.4–44.1 bacteremias was significantly higher than in Gram-positive (2.1 ng/mL, IQR 0.6–7.6 or fungal (0.5 ng/mL, IQR 0.4–1 infections (P<0.0001. Receiver operating characteristic analysis showed an area under the curve (AUC for PCT of 0.765 (95% CI 0.725–0.805, P<0.0001 in discriminating Gram-negatives from Gram-positives at the best cut-off value of 10.8 ng/mL and an AUC of 0.944 (95% CI 0.919–0.969, P<0.0001 in discriminating Gram-negatives from fungi at the best cut-off of 1.6 ng/mL. Additional results showed a significant difference in median PCT values between Enterobacteriaceae and nonfermentative Gram-negative bacteria (17.1 ng/mL, IQR 5.9–48.5 versus 3.5 ng/mL, IQR 0.8–21.5; P<0.0001. This study suggests that PCT may be of value to distinguish Gram-negative from Gram-positive and fungal bloodstream infections. Nevertheless, its utility to predict different microorganisms needs to be assessed in further studies.

Mid-infrared spectroscopic assessment of nanotoxicity in gram-negative vs. gram-positive bacteria.

Science.gov (United States)

Heys, Kelly A; Riding, Matthew J; Strong, Rebecca J; Shore, Richard F; Pereira, M Glória; Jones, Kevin C; Semple, Kirk T; Martin, Francis L

2014-03-07

Nanoparticles appear to induce toxic effects through a variety of mechanisms including generation of reactive oxygen species (ROS), physical contact with the cell membrane and indirect catalysis due to remnants from manufacture. The development and subsequent increasing usage of nanomaterials has highlighted a growing need to characterize and assess the toxicity of nanoparticles, particularly those that may have detrimental health effects such as carbon-based nanomaterials (CBNs). Due to interactions of nanoparticles with some reagents, many traditional toxicity tests are unsuitable for use with CBNs. Infrared (IR) spectroscopy is a non-destructive, high throughput technique, which is unhindered by such problems. We explored the application of IR spectroscopy to investigate the effects of CBNs on Gram-negative (Pseudomonas fluorescens) and Gram-positive (Mycobacterium vanbaalenii PYR-1) bacteria. Two types of IR spectroscopy were compared: attenuated total reflection Fourier-transform infrared (ATR-FTIR) and synchrotron radiation-based FTIR (SR-FTIR) spectroscopy. This showed that Gram-positive and Gram-negative bacteria exhibit differing alterations when exposed to CBNs. Gram-positive bacteria appear more resistant to these agents and this may be due to the protection afforded by their more sturdy cell wall. Markers of exposure also vary according to Gram status; Amide II was consistently altered in Gram-negative bacteria and carbohydrate altered in Gram-positive bacteria. ATR-FTIR and SR-FTIR spectroscopy could both be applied to extract biochemical alterations induced by each CBN that were consistent across the two bacterial species; these may represent potential biomarkers of nanoparticle-induced alterations. Vibrational spectroscopy approaches may provide a novel means of fingerprinting the effects of CBNs in target cells.

Antibacterial Activity of Silver-Graphene Quantum Dots Nanocomposites Against Gram-Positive and Gram-Negative Bacteria

Science.gov (United States)

Habiba, Khaled (Inventor); Makarov, Vladimir (Inventor); Weiner, Brad R (Inventor); Morell, Gerardo (Inventor)

2018-01-01

The invention provides a composite of silver nanoparticles decorated with graphene quantum dots (Ag-GQDs) using pulsed laser synthesis. The nanocomposites were functionalized with polyethylene glycol (PEG). A concentration of 150 .mu.g/mL of Ag-GQDs, a non-toxic level for human cells, exhibits strong antibacterial activity against both Gram-Positive and Gram-Negative Bacteria.

Gram-negative, but not Gram-positive, bacteria elicit strong PGE2 production in human monocytes.

Science.gov (United States)

Hessle, Christina C; Andersson, Bengt; Wold, Agnes E

2003-12-01

Gram-positive and Gram-negative bacteria induce different cytokine patterns in human mononuclear cells. We have seen that Gram-positives preferentially induce IL-12 and TNF-alpha, whereas Gram-negatives induce more IL-10, IL-6, and IL-8. In this study, we compared the capacity of these two groups of bacteria to induce PGE2. Monocytes stimulated with Gram-negative bacterial species induced much more PGE2 than did Gram-positive bacteria (5600 +/- 330 vs. 1700 +/- 670 pg/mL, p Gram-positive and Gram-negative bacteria. We suggest that Gram-positive and Gram-negative bacteria may stimulate different innate effector functions; Gram-positive bacteria promoting cell-mediated effector functions whereas Gram-negative bacteria inducing mediators inhibiting the same.

Type I and Type II mechanisms of antimicrobial photodynamic therapy: an in vitro study on gram-negative and gram-positive bacteria.

Science.gov (United States)

Huang, Liyi; Xuan, Yi; Koide, Yuichiro; Zhiyentayev, Timur; Tanaka, Masamitsu; Hamblin, Michael R

2012-08-01

Antimicrobial photodynamic therapy (APDT) employs a non-toxic photosensitizer (PS) and visible light, which in the presence of oxygen produce reactive oxygen species (ROS), such as singlet oxygen ((1) O(2), produced via Type II mechanism) and hydroxyl radical (HO(.), produced via Type I mechanism). This study examined the relative contributions of (1) O(2) and HO(.) to APDT killing of Gram-positive and Gram-negative bacteria. Fluorescence probes, 3'-(p-hydroxyphenyl)-fluorescein (HPF) and singlet oxygen sensor green reagent (SOSG) were used to determine HO(.) and (1) O(2) produced by illumination of two PS: tris-cationic-buckminsterfullerene (BB6) and a conjugate between polyethylenimine and chlorin(e6) (PEI-ce6). Dimethylthiourea is a HO(.) scavenger, while sodium azide (NaN(3)) is a quencher of (1) O(2). Both APDT and killing by Fenton reaction (chemical generation of HO(.)) were carried out on Gram-positive bacteria (Staphylococcus aureus and Enterococcus faecalis) and Gram-negative bacteria (Escherichia coli, Proteus mirabilis, and Pseudomonas aeruginosa). Conjugate PEI-ce6 mainly produced (1) O(2) (quenched by NaN(3)), while BB6 produced HO(.) in addition to (1) O(2) when NaN(3) potentiated probe activation. NaN(3) also potentiated HPF activation by Fenton reagent. All bacteria were killed by Fenton reagent but Gram-positive bacteria needed a higher concentration than Gram-negatives. NaN(3) potentiated Fenton-mediated killing of all bacteria. The ratio of APDT killing between Gram-positive and Gram-negative bacteria was 2 or 4:1 for BB6 and 25:1 for conjugate PEI-ce6. There was a NaN(3) dose-dependent inhibition of APDT killing using both PEI-ce6 and BB6 against Gram-negative bacteria while NaN(3) almost failed to inhibit killing of Gram-positive bacteria. Azidyl radicals may be formed from NaN(3) and HO(.). It may be that Gram-negative bacteria are more susceptible to HO(.) while Gram-positive bacteria are more susceptible to (1) O(2). The differences in Na

Identification of multidrug-resistant bacteria and Bacillus cereus from ...

African Journals Online (AJOL)

However, B. cereus was isolated from the hands of three. HCWs. Table 1 shows species of bacteria isolated from. HCWs and ES in Elkhomes hospital. B. cereus is a Gram-positive spore-forming facultative- anaerobic rod-shaped organism that can be found in different types of soils and widely distributed in the environment.

Recent Advances in the Study of Bipolar/Rod-Shaped Microglia and their Roles in Neurodegeneration

Directory of Open Access Journals (Sweden)

Ngan Pan Bennett Au

2017-05-01

Full Text Available Microglia are the resident immune cells of the central nervous system (CNS and they contribute to primary inflammatory responses following CNS injuries. The morphology of microglia is closely associated with their functional activities. Most previous research efforts have attempted to delineate the role of ramified and amoeboid microglia in the pathogenesis of neurodegenerative diseases. In addition to ramified and amoeboid microglia, bipolar/rod-shaped microglia were first described by Franz Nissl in 1899 and their presence in the brain was closely associated with the pathology of infectious diseases and sleeping disorders. However, studies relating to bipolar/rod-shaped microglia are very limited, largely due to the lack of appropriate in vitro and in vivo experimental models. Recent studies have reported the formation of bipolar/rod-shaped microglia trains in in vivo models of CNS injury, including diffuse brain injury, focal transient ischemia, optic nerve transection and laser-induced ocular hypertension (OHT. These bipolar/rod-shaped microglia formed end-to-end alignments in close proximity to the adjacent injured axons, but they showed no interactions with blood vessels or other types of glial cell. Recent studies have also reported on a highly reproducible in vitro culture model system to enrich bipolar/rod-shaped microglia that acts as a powerful tool with which to characterize this form of microglia. The molecular aspects of bipolar/rod-shaped microglia are of great interest in the field of CNS repair. This review article focuses on studies relating to the morphology and transformation of microglia into the bipolar/rod-shaped form, along with the differential gene expression and spatial distribution of bipolar/rod-shaped microglia in normal and pathological CNSs. The spatial arrangement of bipolar/rod-shaped microglia is crucial in the reorganization and remodeling of neuronal and synaptic circuitry following CNS injuries. Finally, we

Veillonella, Firmicutes: Microbes disguised as Gram negatives

DEFF Research Database (Denmark)

Vesth, Tammi Camilla; Ozen, Asli; Andersen, Sandra Christine

2013-01-01

Negativicutes, including the genus Veillonella, stain Gram negative. Veillonella are among the most abundant organisms of the oral and intestinal microflora of animals and humans, in spite of being strict anaerobes. In this work, the genomes of 24 Negativicutes, including eight Veillonella spp., are compared......, with the exception of a shared LPS biosynthesis pathway. The clade within the class Negativicutes to which the genus Veillonella belongs exhibits unique properties, most of which are in common with Gram-positives and some with Gram negatives. They are only distantly related to Clostridia, but are even less closely...... related to Gram-negative species. Though the Negativicutes stain Gram-negative and possess two membranes, the genome and proteome analysis presented here confirm their place within the (mainly) Gram positive phylum of the Firmicutes. Further studies are required to unveil the evolutionary history...

Antibiotic-Resistant Gram Negative Bacilli in Meals Delivered at a General Hospital, Italy

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Maria Rosa Anna Plano

2009-01-01

Full Text Available This study aimed at detecting the presence of antibiotic-resistant Gram-negatives in samples of meals delivered at the University General Hospital of Palermo, Italy. Antibiotic resistant Gram negatives were isolated in July—September 2007 ffrom cold dishes and food contact surfaces and utensils. Bacterial strains were submitted to susceptibility test and subtyped by random amplification of polymorphic DNA (RAPD. Forty-six of 55 (83.6% food samples and 14 of 17 (82.3% environmental swabs were culture positive for Gram negative bacilli resistant to at least one group of antibacterial drugs. A total of 134 antibiotic resistant strains, 51 fermenters and 83 non-fermenters, were recovered. Fermenters and non-fermenters showed frequencies as high as 97.8% of resistance to two or more groups of antibiotics and non fermenters were 28.9% resistant to more than three groups. Molecular typing detected 34 different profiles among the fermenters and 68 among the non-fermenters. Antibiotic resistance was very common among both fermenters and non-fermenters. However, the wide heterogeneity of RAPD patterns seems to support a prominent role of cross-contamination rather than a clonal expansion of a few resistant isolates. A contribution of commensal Gram negatives colonizing foods to a common bacterial resistance pool should not been overlooked.

Antibiotic-resistant gram negative bacilli in meals delivered at a general hospital, Italy.

Science.gov (United States)

Plano, Maria Rosa Anna; Di Noto, Anna Maria; Firenze, Alberto; Sciortino, Sonia; Mammina, Caterina

2009-01-01

This study aimed at detecting the presence of antibiotic-resistant Gram-negatives in samples of meals delivered at the University General Hospital of Palermo, Italy. Antibiotic resistant Gram negatives were isolated in July-September 2007 ffrom cold dishes and food contact surfaces and utensils. Bacterial strains were submitted to susceptibility test and subtyped by random amplification of polymorphic DNA (RAPD). Forty-six of 55 (83.6%) food samples and 14 of 17 (82.3%) environmental swabs were culture positive for Gram negative bacilli resistant to at least one group of antibacterial drugs. A total of 134 antibiotic resistant strains, 51 fermenters and 83 non-fermenters, were recovered. Fermenters and non-fermenters showed frequencies as high as 97.8% of resistance to two or more groups of antibiotics and non fermenters were 28.9% resistant to more than three groups. Molecular typing detected 34 different profiles among the fermenters and 68 among the non-fermenters. Antibiotic resistance was very common among both fermenters and non-fermenters. However, the wide heterogeneity of RAPD patterns seems to support a prominent role of cross-contamination rather than a clonal expansion of a few resistant isolates. A contribution of commensal Gram negatives colonizing foods to a common bacterial resistance pool should not been overlooked.

Multiplex identification of sepsis-causing Gram-negative pathogens from the plasma of infected blood.

Science.gov (United States)

Chung, Boram; Park, Chulmin; Cho, Sung-Yeon; Shin, Juyoun; Shin, Sun; Yim, Seon-Hee; Lee, Dong-Gun; Chung, Yeun-Jung

2018-02-01

Early and accurate detection of bacterial pathogens in the blood is the most crucial step for sepsis management. Gram-negative bacteria are the most common organisms causing severe sepsis and responsible for high morbidity and mortality. We aimed to develop a method for rapid multiplex identification of clinically important Gram-negative pathogens and also validated whether our system can identify Gram-negative pathogens with the cell-free plasm DNA from infected blood. We designed five MLPA probe sets targeting the genes specific to major Gram-negative pathogens (uidA and lacY for E. coli, ompA for A. baumannii, phoE for K. pneumoniae, and ecfX for P. aeruginosa) and one set targeting the CTX-M group 1 to identify the ESBL producing Gram-negative pathogens. All six target-specific peaks were clearly separated without any non-specific peaks in a multiplex reaction condition. The minimum detection limit was 100 fg of pathogen DNA. When we tested 28 Gram-negative clinical isolates, all of them were successfully identified without any non-specific peaks. To evaluate the clinical applicability, we tested seven blood samples from febrile patients. Three blood culture positive cases showed E. coli specific peaks, while no peak was detected in the other four culture negative samples. This technology can be useful for detection of major sepsis-causing, drug-resistant Gram-negative pathogens and also the major ESBL producing Gram-negatives from the blood of sepsis patients in a clinical setting. This system can help early initiation of effective antimicrobial treatment against Gram-negative pathogens for sepsis patients, which is very crucial for better treatment outcomes. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Morphogenic Protein RodZ Interacts with Sporulation Specific SpoIIE in Bacillus subtilis.

Science.gov (United States)

Muchová, Katarína; Chromiková, Zuzana; Bradshaw, Niels; Wilkinson, Anthony J; Barák, Imrich

2016-01-01

The first landmark in sporulation of Bacillus subtilis is the formation of an asymmetric septum followed by selective activation of the transcription factor σF in the resulting smaller cell. How the morphological transformations that occur during sporulation are coupled to cell-specific activation of transcription is largely unknown. The membrane protein SpoIIE is a constituent of the asymmetric sporulation septum and is a crucial determinant of σF activation. Here we report that the morphogenic protein, RodZ, which is essential for cell shape determination, is additionally required for asymmetric septum formation and sporulation. In cells depleted of RodZ, formation of asymmetric septa is disturbed and σF activation is perturbed. During sporulation, we found that SpoIIE recruits RodZ to the asymmetric septum. Moreover, we detected a direct interaction between SpoIIE and RodZ in vitro and in vivo, indicating that SpoIIE-RodZ may form a complex to coordinate asymmetric septum formation and σF activation. We propose that RodZ could provide a link between the cell shape machinery and the coordinated morphological and developmental transitions required to form a resistant spore.

Distribution of multi-resistant Gram-negative versus Gram-positive bacteria in the hospital inanimate environment.

Science.gov (United States)

Lemmen, S W; Häfner, H; Zolldann, D; Stanzel, S; Lütticken, R

2004-03-01

We prospectively studied the difference in detection rates of multi-resistant Gram-positive and multi-resistant Gram-negative bacteria in the inanimate environment of patients harbouring these organisms. Up to 20 different locations around 190 patients were surveyed. Fifty-four patients were infected or colonized with methicillin-resistant Staphylococcus aureus (MRSA) or vancomycin-resistant enterococci (VRE) and 136 with multi-resistant Gram-negative bacteria. The environmental detection rate for MRSA or VRE was 24.7% (174/705 samples) compared with 4.9% (89/1827 samples) for multi-resistant Gram-negative bacteria (PGram-positive bacteria were isolated more frequently than Gram-negatives from the hands of patients (PGram-positive and Gram-negative isolates. Our results suggest that the inanimate environment serves as a secondary source for MRSA and VRE, but less so for Gram-negative bacteria. Thus, strict contact isolation in a single room with complete barrier precautions is recommended for MRSA or VRE; however, for multi-resistant Gram-negative bacteria, contact isolation with barrier precautions for close contact but without a single room seems sufficient. This benefits not only the patients, but also the hospital by removing some of the strain placed on already over-stretched resources.

Genome sequence of Ensifer arboris strain LMG 14919T; a microsymbiont of the legume Prosopis chilensis growing in Kosti, Sudan

OpenAIRE

Reeve, Wayne; Tian, Rui; Bräu, Lambert; Goodwin, Lynne; Munk, Christine; Detter, Chris; Tapia, Roxanne; Han, Cliff; Liolios, Konstantinos; Huntemann, Marcel; Pati, Amrita; Woyke, Tanja; Mavrommatis, Konstantinos; Markowitz, Victor; Ivanova, Natalia

2013-01-01

Ensifer arboris LMG 14919T is an aerobic, motile, Gram-negative, non-spore-forming rod that can exist as a soil saprophyte or as a legume microsymbiont of several species of legume trees. LMG 14919T was isolated in 1987 from a nodule recovered from the roots of the tree Prosopis chilensis growing in Kosti, Sudan. LMG 14919T is highly effective at fixing nitrogen with P. chilensis (Chilean mesquite) and Acacia senegal (gum Arabic tree or gum acacia). LMG 14919T does not nodulate the tree Leuce...

Rod-Shaped Magnetite Nano/Microparticles Synthesis at Ambient Temperature

Directory of Open Access Journals (Sweden)

Balaprasad Ankamwar

2013-01-01

Full Text Available Here, we reported room temperature synthesis of Fe3O4 rod-shaped nano/microparticles by chemical reduction method from FeCl3 precursor and NaBH4 as the reducing agent in the presence of the pyrrole as a capping agent. The magnetic Fe3O4 particles were characterized by several methods, such as SEM, XRD, FTIR, and TGA. The average aspect ratio of Fe3O4 rod-shaped particles was ~2.8. These particles were redispersed in deionised water to form a colloidal solution and showed magnetic properties. This economical synthesis route is scalable, and Fe3O4 particles can be exploited for various applications such as MRI contrast enhancement, biodiseperations, Ni-Fe batteries, and as a catalyst.

Gram-negative diabetic foot osteomyelitis: risk factors and clinical presentation.

Science.gov (United States)

Aragón-Sánchez, Javier; Lipsky, Benjamin A; Lázaro-Martínez, Jose L

2013-03-01

Osteomyelitis frequently complicates infections in the feet of patients with diabetes. Gram-positive cocci, especially Staphylococcus aureus, are the most commonly isolated pathogens, but gram-negative bacteria also cause some cases of diabetic foot osteomyelitis (DFO). These gram-negatives require different antibiotic regimens than those commonly directed at gram-positives. There are, however, few data on factors related to their presence and how they influence the clinical picture. We conducted a retrospective study to determine the variables associated with the isolation of gram-negative bacteria from bone samples in cases of DFO and the clinical presentation of these infections. Among 341 cases of DFO, 150 had a gram-negative isolate (alone or combined with a gram-positive isolate) comprising 44.0% of all patients and 50.8% of those with a positive bone culture. Compared with gram-positive infections, wounds with gram-negative organisms more often had a fetid odor, necrotic tissue, signs of soft tissue infection accompanying osteomyelitis, and clinically severe infection. By multivariate analysis, the predictive variables related to an increased likelihood of isolating gram-negatives from bone samples were glycated hemoglobin gram-negatives had a statistically significantly higher prevalence of leukocytosis and higher white blood cell counts than those without gram-negatives. In conclusion, gram-negative organisms were isolated in nearly half of our cases of DFO and were associated with more severe infections, higher white blood cell counts, lower glycated hemoglobin levels, and wounds of traumatic etiology.

Antimicrobial resistance pattern of Gram –negative bacilli isolated of Vali-Asr Hospital wards in Arak

Directory of Open Access Journals (Sweden)

Farshid Didgar

2014-11-01

Full Text Available Background: Infectious diseases are of the most important causes of mortality all around the world particular in developing countries. Recently, the most important thing that has worried medical society is antibiotic resistance. Multi-resistant gram_negative rods are important pathogens in hospitals, causing high rate of mortality.The main goal of this study was to investigate the antimicrobial resistance patterns among common gram-negative bacilli isolated from patients of Vali-Asr Hospital. Material and Methods: This is a cross-sectional descriptive study conducted between the years 2010-2012 in Vali-Asr hospital in Arak. In this study 1120 specimen were examined. Bacterial strains were isolated by conventional methods from various clinical samples of patients including: blood, urine, wound, sputum, CSF, andetc.All isolates were examined for antimicrobial resistance using disc diffusion method. Results: In this study 737 specimen were positive cultures. A total of 332 isolates of Gram-negative bacilli were identified. The most frequent gram negative bacteria were isolated from urine, wound, blood, respiratory secretion and catheter. The most frequent pathogens were E.coli followed by k.pneumonia, entrobacter, p.oaeruginosa, Acinetobacter spp, citrobacter and proteus. High rate of resistance to third generation of cephalospoins & carbapenems observed amang isolates of Acintobacter spp.Prodution of extended spectrum beralactamases (ESBLS was found in 51.4% of all Gram negative bacteria. Conclusion: Antibiotic resistance, particularly multi-drug resistance is frequent among microorganisms of ValiAsr Hospital. Resistance in our country, like other countries have been shown to be increased, so it is highly recommended to prohibit unnecessary prescription of antibiotics.

Drug-resistant gram-negative uropathogens: A review.

Science.gov (United States)

Khoshnood, Saeed; Heidary, Mohsen; Mirnejad, Reza; Bahramian, Aghil; Sedighi, Mansour; Mirzaei, Habibollah

2017-10-01

Urinary tract infection(UTI) caused by Gram-negative bacteria is the second most common infectious presentation in community medical practice. Approximately 150 million people are diagnosed with UTI each year worldwide. Drug resistance in Gram-negative uropathogens is a major global concern which can lead to poor clinical outcomes including treatment failure, development of bacteremia, requirement for intravenous therapy, hospitalization, and extended length of hospital stay. The mechanisms of drug resistance in these bacteria are important due to they are often not identified by routine susceptibility tests and have an exceptional potential for outbreaks. Treatment of UTIs depends on the access to effective drugs, which is now threatened by antibiotic resistant Gram-negative uropathogens. Although several effective antibiotics with activity against highly resistant Gram-negatives are available, there is not a unique antibiotic with activity against the high variety of resistance. Therefore, antimicrobial susceptibility tests, correlation between clinicians and laboratories, development of more rapid diagnostic methods, and continuous monitoring of drug resistance are urgent priorities. In this review, we will discuss about the current global status of drug-resistant Gram-negative uropathogens and their mechanisms of drug resistance to provide new insights into their treatment options. Copyright © 2017 Elsevier Masson SAS. All rights reserved.

Serratia bozhouensis sp. nov., Isolated from Sewage Samples of a Dairy Farm.

Science.gov (United States)

Shang, Fei; Xue, Ting; Wang, Man; Chen, Xiaolin; Yu, Li; Zhang, Ming

2017-07-01

A Gram-negative, rod-shaped, salt-tolerant, non-pigmented, and non-spore-forming bacterium, designated strain W1 T (type strain CICC 23797 = CGMCC1.14949), was isolated from sewage samples of a dairy farm in Bozhou, Anhui, China. Strain W1 was resistant to lincomycin, troleandomycin, rifamycin, and vancomycin. Sequence analysis of the 16S rDNA gene revealed that the strain showed sequence similarity of 98.2% with the closest related species Serratia quinivorans CP6a T . The genomic DNA G+C content of the isolate was 52.8 mol%. The biochemical characteristics of strain W1 T assessed by the API 20E and Biolog GEN III analysis were different from those of the members of the genus Serratia. On the basis of the phenotypic and genotypic differences, strain W1 was proposed to be a novel Serratia species, Serratia bozhouensis sp. nov W1 T .

Isolation and Characterization of Acetate-Utilizing Anaerobes from a Freshwater Sediment.

Science.gov (United States)

Scholten, J.C.M.; Stams, A.J.M.

2000-12-01

Acetate-degrading anaerobic microorganisms in freshwater sediment were quantified by the most probable number technique. From the highest dilutions a methanogenic, a sulfate-reducing, and a nitrate-reducing microorganism were isolated with acetate as substrate. The methanogen (culture AMPB-Zg) was non-motile and rod-shaped with blunted ends (0.5-1 mm x 3-4 mm long). Doubling times with acetate at 30-35 degrees C were 5.6-8.1 days. The methanogen grew only on acetate. Analysis of the 16S rRNA sequence showed that AMPB-Zg is closely related to Methanosaeta concilii. The isolated sulfate-reducing bacterium (strain ASRB-Zg) was rod-shaped with pointed ends (0.5-0.7 mm x 1.5-3.5 mm long), weakly motile, spore forming, and gram positive. At the optimum growth temperature of 30 degrees C the doubling times with acetate were 3.9-5.3 days. The bacterium grew on a range of organic acids, such as acetate, butyrate, fumarate, and benzoate, but did not grow autotrophically with H2, CO2, and sulfate. The closest relative of strain ASRB-Zg is Desulfotomaculum acetoxidans. The nitrate-reducing bacterium (strain ANRB-Zg) was rod-shaped (0.5-0.7 mm x 0.7-1 mm long), weakly motile, and gram negative. Optimum growth with acetate occurred at 20-25 degrees C. The bacterium grew on a range of organic substrates, such as acetate, butyrate, lactate, and glucose, and did grow autotrophically with H2, CO2, and oxygen but not with nitrate. In the presence of acetate and nitrate, thiosulfate was oxidized to sulfate. Phylogenetically, the closest relative of strain ANRB-Zg is Variovorax paradoxus.

An evaluation of canonical forms for non-rigid 3D shape retrieval

OpenAIRE

Pickup, David; Liu, Juncheng; Sun, Xianfang; Rosin, Paul L.; Martin, Ralph R.; Cheng, Zhiquan; Lian, Zhouhui; Nie, Sipin; Jin, Longcun; Shamai, Gil; Sahillioğlu, Yusuf; Kavan, Ladislav

2018-01-01

Canonical forms attempt to factor out a non-rigid shape’s pose, giving a pose-neutral shape. This opens up the\\ud possibility of using methods originally designed for rigid shape retrieval for the task of non-rigid shape retrieval.\\ud We extend our recent benchmark for testing canonical form algorithms. Our new benchmark is used to evaluate a\\ud greater number of state-of-the-art canonical forms, on five recent non-rigid retrieval datasets, within two different\\ud retrieval frameworks. A tota...

Characterization of the Extended-Spectrum beta-Lactamase Producers among Non-Fermenting Gram-Negative Bacteria Isolated from Burnt Patients

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Mojdeh Hakemi Vala

2013-09-01

Full Text Available Please cite this article as: Hakemi Vala M, Hallajzadeh M, Fallah F, Hashemi A, Goudarzi H. Characterization of the extended-spectrum beta-lactamase producers among non-fermenting gram-negative bacteria isolated from burnt patients. Arch Hyg Sci 2013;2(1:1-6. Background & Aims of the Study: Extended-spectrum beta-Lactamases (ESBLs represent a major group of beta-lactamases which are responsible for resistance to oxyimino-cephalosporins and aztreonam and currently being identified in large numbers throughout the world. The objective of this study was to characterize ESBL producers among non-fermenter gram-negative bacteria isolated from burnt patients. Materials & Methods: During April to July 2012, 75 non-fermenter gram-negative bacilli were isolated from 240 bacterial cultures collected from wounds of burnt patients admitted to the Burn Unit at Shahid Motahari Hospital (Tehran, Iran. Bacterial isolation and identification was done using standard methods. Antimicrobial susceptibility testing was performed by disk diffusion method for all strains against selected antibiotics and minimum inhibitory concentration was determined by microdilution test. The ability to produce ESBL was detected through double disk synergy test among candidate strains. Results: Of 75 non-fermenter isolates, 47 Pseudomonas aeruginosa and 28 Acinetobacter baumannii were identified. The resistance of P. aeruginosa isolates to tested antibiotics in antibiogram test were 100% to cefpodoxime, 82.98% to ceftriaxone, 78.73% to imipenem, 75% to meropenem, 72.72% to gentamicin, 69.23% to ciprofloxacin and aztreonam, 67.57% to cefepime, 65.95% to ceftazidime, and 61.53% to piperacillin. The results for Acinetobacter baumannii were 100% to ceftazidime, cefepime, ciprofloxacin, imipenem, meropenem, cefpodoxime, and cefotaxim, 96.85% to gentamicin, 89.65% to ceftriaxone, 65.51% to aztreonam, and 40% to piperacillin. Double disk synergy test showed that 21 (28% of non

Thermoanaerobacter mathranii sp. nov., an ethanol-producing, extremely thermophilic anaerobic bacterium from a hot spring in Iceland

DEFF Research Database (Denmark)

Larsen, L.; Nielsen, P.; Ahring, B.K.

1997-01-01

The extremely thermophilic ethanol-producing strain A3 was isolated from a hot spring in Iceland, The cells were rod-shaped, motile, and had terminal spores: cells from the mid-to-late exponential growth phase stained gram-variable but had a gram-positive cell wall structure when viewed...

Gram positive and Gram negative bacteria differ in their sensitivity to cold plasma

Science.gov (United States)

Mai-Prochnow, Anne; Clauson, Maryse; Hong, Jungmi; Murphy, Anthony B.

2016-12-01

Cold atmospheric-pressure plasma (CAP) is a relatively new method being investigated for antimicrobial activity. However, the exact mode of action is still being explored. Here we report that CAP efficacy is directly correlated to bacterial cell wall thickness in several species. Biofilms of Gram positive Bacillus subtilis, possessing a 55.4 nm cell wall, showed the highest resistance to CAP, with less than one log10 reduction after 10 min treatment. In contrast, biofilms of Gram negative Pseudomonas aeruginosa, possessing only a 2.4 nm cell wall, were almost completely eradicated using the same treatment conditions. Planktonic cultures of Gram negative Pseudomonas libanensis also had a higher log10 reduction than Gram positive Staphylococcus epidermidis. Mixed species biofilms of P. aeruginosa and S. epidermidis showed a similar trend of Gram positive bacteria being more resistant to CAP treatment. However, when grown in co-culture, Gram negative P. aeruginosa was more resistant to CAP overall than as a mono-species biofilm. Emission spectra indicated OH and O, capable of structural cell wall bond breakage, were present in the plasma. This study indicates that cell wall thickness correlates with CAP inactivation times of bacteria, but cell membranes and biofilm matrix are also likely to play a role.

Synergistic action of cinnamaldehyde with silver nanoparticles against spore-forming bacteria: a case for judicious use of silver nanoparticles for antibacterial applications

Directory of Open Access Journals (Sweden)

Ghosh IN

2013-12-01

Full Text Available Indro Neil Ghosh,1,* Supriya Deepak Patil,1,* Tarun Kumar Sharma,1,2 Santosh Kumar Srivastava,1 Ranjana Pathania,1 Naveen Kumar Navani11Department of Biotechnology, Indian Institute of Technology Roorkee, Roorkee, Uttarakhand, 2Center for Biodesign and Diagnostics, Translational Health Science and Technology Institute, Gurgaon Haryana, India*These authors contributed equally to this workAbstract: Silver has long been advocated as an effective antimicrobial. However, toxicity issues with silver have led to limited use of silver in nanoform, especially for food preservation. With the aim of exploring combinatorial options that could increase the antibacterial potency of silver nanoparticles and reduce the effective dosage of silver, we evaluated the extent of synergy that a combination of silver nanoparticles and an essential oil representative (cinnamaldehyde could offer. A battery of gram-positive and gram-negative bacterial strains was utilized for antibacterial assays, and extents of synergism were calculated from fractional inhibitory concentration indices. The activity of nanoparticles was greatly enhanced when utilized in the presence of cinnamaldehyde. We observed combinatorial effects that were strongly additive against all the bacterial strains tested, and genuine synergy was found against spore forming Bacillus cereus and Clostridium perfringens – bacterial strains associated with release of cytotoxins in contaminated food and known for their persistence. Bacterial kill curve analysis revealed a very fast bactericidal action when a combination of two agents was used. The electron and atomic force microscopy also revealed extensive damage to the bacterial cell envelop in the presence of both agents. We also performed hemolysis assays to investigate and approximate the extent of toxicity exhibited by the two agents, and observed no adverse effect at the concentrations required for synergy. This study shows that safe levels of silver in

Veillonella, Firmicutes: Microbes disguised as Gram negatives.

Science.gov (United States)

Vesth, Tammi; Ozen, Aslı; Andersen, Sandra C; Kaas, Rolf Sommer; Lukjancenko, Oksana; Bohlin, Jon; Nookaew, Intawat; Wassenaar, Trudy M; Ussery, David W

2013-12-20

The Firmicutes represent a major component of the intestinal microflora. The intestinal Firmicutes are a large, diverse group of organisms, many of which are poorly characterized due to their anaerobic growth requirements. Although most Firmicutes are Gram positive, members of the class Negativicutes, including the genus Veillonella, stain Gram negative. Veillonella are among the most abundant organisms of the oral and intestinal microflora of animals and humans, in spite of being strict anaerobes. In this work, the genomes of 24 Negativicutes, including eight Veillonella spp., are compared to 20 other Firmicutes genomes; a further 101 prokaryotic genomes were included, covering 26 phyla. Thus a total of 145 prokaryotic genomes were analyzed by various methods to investigate the apparent conflict of the Veillonella Gram stain and their taxonomic position within the Firmicutes. Comparison of the genome sequences confirms that the Negativicutes are distantly related to Clostridium spp., based on 16S rRNA, complete genomic DNA sequences, and a consensus tree based on conserved proteins. The genus Veillonella is relatively homogeneous: inter-genus pair-wise comparison identifies at least 1,350 shared proteins, although less than half of these are found in any given Clostridium genome. Only 27 proteins are found conserved in all analyzed prokaryote genomes. Veillonella has distinct metabolic properties, and significant similarities to genomes of Proteobacteria are not detected, with the exception of a shared LPS biosynthesis pathway. The clade within the class Negativicutes to which the genus Veillonella belongs exhibits unique properties, most of which are in common with Gram-positives and some with Gram negatives. They are only distantly related to Clostridia, but are even less closely related to Gram-negative species. Though the Negativicutes stain Gram-negative and possess two membranes, the genome and proteome analysis presented here confirm their place within the

Revisiting the Gram-negative lipoprotein paradigm.

Science.gov (United States)

LoVullo, Eric D; Wright, Lori F; Isabella, Vincent; Huntley, Jason F; Pavelka, Martin S

2015-05-01

The processing of lipoproteins (Lpps) in Gram-negative bacteria is generally considered an essential pathway. Mature lipoproteins in these bacteria are triacylated, with the final fatty acid addition performed by Lnt, an apolipoprotein N-acyltransferase. The mature lipoproteins are then sorted by the Lol system, with most Lpps inserted into the outer membrane (OM). We demonstrate here that the lnt gene is not essential to the Gram-negative pathogen Francisella tularensis subsp. tularensis strain Schu or to the live vaccine strain LVS. An LVS Δlnt mutant has a small-colony phenotype on sucrose medium and increased susceptibility to globomycin and rifampin. We provide data indicating that the OM lipoprotein Tul4A (LpnA) is diacylated but that it, and its paralog Tul4B (LpnB), still sort to the OM in the Δlnt mutant. We present a model in which the Lol sorting pathway of Francisella has a modified ABC transporter system that is capable of recognizing and sorting both triacylated and diacylated lipoproteins, and we show that this modified system is present in many other Gram-negative bacteria. We examined this model using Neisseria gonorrhoeae, which has the same Lol architecture as that of Francisella, and found that the lnt gene is not essential in this organism. This work suggests that Gram-negative bacteria fall into two groups, one in which full lipoprotein processing is essential and one in which the final acylation step is not essential, potentially due to the ability of the Lol sorting pathway in these bacteria to sort immature apolipoproteins to the OM. This paper describes the novel finding that the final stage in lipoprotein processing (normally considered an essential process) is not required by Francisella tularensis or Neisseria gonorrhoeae. The paper provides a potential reason for this and shows that it may be widespread in other Gram-negative bacteria. Copyright © 2015, American Society for Microbiology. All Rights Reserved.

Silver enhances antibiotic activity against gram-negative bacteria.

Science.gov (United States)

Morones-Ramirez, J Ruben; Winkler, Jonathan A; Spina, Catherine S; Collins, James J

2013-06-19

A declining pipeline of clinically useful antibiotics has made it imperative to develop more effective antimicrobial therapies, particularly against difficult-to-treat Gram-negative pathogens. Silver has been used as an antimicrobial since antiquity, yet its mechanism of action remains unclear. We show that silver disrupts multiple bacterial cellular processes, including disulfide bond formation, metabolism, and iron homeostasis. These changes lead to increased production of reactive oxygen species and increased membrane permeability of Gram-negative bacteria that can potentiate the activity of a broad range of antibiotics against Gram-negative bacteria in different metabolic states, as well as restore antibiotic susceptibility to a resistant bacterial strain. We show both in vitro and in a mouse model of urinary tract infection that the ability of silver to induce oxidative stress can be harnessed to potentiate antibiotic activity. Additionally, we demonstrate in vitro and in two different mouse models of peritonitis that silver sensitizes Gram-negative bacteria to the Gram-positive-specific antibiotic vancomycin, thereby expanding the antibacterial spectrum of this drug. Finally, we used silver and antibiotic combinations in vitro to eradicate bacterial persister cells, and show both in vitro and in a mouse biofilm infection model that silver can enhance antibacterial action against bacteria that produce biofilms. This work shows that silver can be used to enhance the action of existing antibiotics against Gram-negative bacteria, thus strengthening the antibiotic arsenal for fighting bacterial infections.

Epidemiology of infections caused by multiresistant gram-negatives: ESBLs, MBLs, panresistant strains.

Science.gov (United States)

Rossolini, Gian Maria; Mantengoli, Elisabetta; Docquier, Jean-Denis; Musmanno, Rosa Anna; Coratza, Grazietta

2007-07-01

Microbial drug resistance is a growing problem of global magnitude. In gram-negative pathogens, the most important resistance problems are encountered in Enterobacteriaceae, Pseudomonas aeruginosa and Acinetobacter, with increasing trends observed for all major anti-gram-negative agents (beta-lactams, fluoroquinolones and aminoglycosides). A matter of major concern is the emergence of new beta-lactamases capable of degrading the expanded-spectrum cephalosporins and/or carbapenems, such as the extended-spectrum beta-lactamases (ESBLs) and the carbapenemases. These beta-lactamase genes are often associated with resistance determinants to non-beta-lactam agents (e.g. aminoglycosides and fluoroquinolones), and strains producing ESBLs or carbapenemases often exhibit complex multidrug resistant phenotypes and sometimes are panresistant. The problem is worsened by the dearth of new agents active on multidrug-resistant Gram-negatives in the pipeline. The importance to develop better strategies to control resistance is underscored.

Nuclear reactor fuel rod attachment system

International Nuclear Information System (INIS)

Christiansen, D.W.

1983-01-01

The invention involves a technique to quickly, inexpensively and rigidly attach a nuclear reactor fuel rod to a support member. The invention also allows for the repeated non-destructive removal and replacement of the fuel rod. The proposed fuel rod and support member attachment and removal system consists of a locking cap fastened to the fuel rod and a locking strip fastened to the support member or vice versa. The locking cap has two or more opposing fingers shaped to form a socket. The fingers spring back when moved apart and released. The locking strip has an extension shaped to rigidly attach to the socket's body portion

Global transcriptome analysis of spore formation in Myxococcus xanthus reveals a locus necessary for cell differentiation

Directory of Open Access Journals (Sweden)

Treuner-Lange Anke

2010-04-01

Full Text Available Abstract Background Myxococcus xanthus is a Gram negative bacterium that can differentiate into metabolically quiescent, environmentally resistant spores. Little is known about the mechanisms involved in differentiation in part because sporulation is normally initiated at the culmination of a complex starvation-induced developmental program and only inside multicellular fruiting bodies. To obtain a broad overview of the sporulation process and to identify novel genes necessary for differentiation, we instead performed global transcriptome analysis of an artificial chemically-induced sporulation process in which addition of glycerol to vegetatively growing liquid cultures of M. xanthus leads to rapid and synchronized differentiation of nearly all cells into myxospore-like entities. Results Our analyses identified 1 486 genes whose expression was significantly regulated at least two-fold within four hours of chemical-induced differentiation. Most of the previously identified sporulation marker genes were significantly upregulated. In contrast, most genes that are required to build starvation-induced multicellular fruiting bodies, but which are not required for sporulation per se, were not significantly regulated in our analysis. Analysis of functional gene categories significantly over-represented in the regulated genes, suggested large rearrangements in core metabolic pathways, and in genes involved in protein synthesis and fate. We used the microarray data to identify a novel operon of eight genes that, when mutated, rendered cells unable to produce viable chemical- or starvation-induced spores. Importantly, these mutants displayed no defects in building fruiting bodies, suggesting these genes are necessary for the core sporulation process. Furthermore, during the starvation-induced developmental program, these genes were expressed in fruiting bodies but not in peripheral rods, a subpopulation of developing cells which do not sporulate

The predominant circular form of avocado sunblotch viroid accumulates in planta as a free RNA adopting a rod-shaped secondary structure unprotected by tightly bound host proteins.

Science.gov (United States)

López-Carrasco, Amparo; Flores, Ricardo

2017-07-01

Avocado sunblotch viroid (ASBVd), the type member of the family Avsunviroidae, replicates and accumulates in chloroplasts. Whether this minimal non-protein-coding circular RNA of 246-250 nt exists in vivo as a free nucleic acid or closely associated with host proteins remains unknown. To tackle this issue, the secondary structures of the monomeric circular (mc) (+) and (-) strands of ASBVd have been examined in silico by searching those of minimal free energy, and in vitro at single-nucleotide resolution by selective 2'-hydroxyl acylation analysed by primer extension (SHAPE). Both approaches resulted in predominant rod-like secondary structures without tertiary interactions, with the mc (+) RNA being more compact than its (-) counterpart as revealed by non-denaturing polyacryamide gel electrophoresis. Moreover, in vivo SHAPE showed that the mc ASBVd (+) form accumulates in avocado leaves as a free RNA adopting a similar rod-shaped conformation unprotected by tightly bound host proteins. Hence, the mc ASBVd (+) RNA behaves in planta like the previously studied mc (+) RNA of potato spindle tuber viroid, the type member of nuclear viroids (family Pospiviroidae), indicating that two different viroids replicating and accumulating in distinct subcellular compartments, have converged into a common structural solution. Circularity and compact secondary structures confer to these RNAs, and probably to all viroids, the intrinsic stability needed to survive in their natural habitats. However, in vivo SHAPE has not revealed the (possibly transient or loose) interactions of the mc ASBVd (+) RNA with two host proteins observed previously by UV irradiation of infected avocado leaves.

Magnetic engineering of stable rod-shaped stem cell aggregates: circumventing the pitfall of self-bending.

Science.gov (United States)

Du, V; Fayol, D; Reffay, M; Luciani, N; Bacri, J-C; Gay, C; Wilhelm, C

2015-02-01

A current challenge for tissue engineering while restoring the function of diseased or damaged tissue is to customize the tissue according to the target area. Scaffold-free approaches usually yield spheroid shapes with the risk of necrosis at the center due to poor nutrient and oxygen diffusion. Here, we used magnetic forces developed at the cellular scale by miniaturized magnets to create rod-shaped aggregates of stem cells that subsequently matured into a tissue-like structure. However, during the maturation process, the tissue-rods spontaneously bent and coiled into sphere-like structures, triggered by the increasing cell-cell adhesion within the initially non-homogeneous tissue. Optimisation of the intra-tissular magnetic forces successfully hindered the transition, in order to produce stable rod-shaped stem cells aggregates.

Absorption edge imaging of sporocide-treated and non-treated bacterial spores

International Nuclear Information System (INIS)

Panessa-Warren, B.J.; Tortora, G.T.; Warren, J.B.

1987-01-01

When deprived of nutrients, spore forming bacilli produce endospores which are remarkably resistant to chemical sterilization. Little is known about the morphology and response fo these spores following exposure to sporocidal agents. Light microscopy does not provide sufficient resolution for studying the rupture of the spore coat and fate of intracellular material. Transmission and scanning electron microscopy offer superior resolution but require specimen preparation methods that induce physiologic as well as morphologic changes in the spores, thereby making accurate interpretation of micrographs difficult. To eliminate the possible artifacts induced by chemical fixation, dehydration, embeddment, staining and sectioning, treated and non-sporocide-treated endospores of B. thuringiensis and B. subtilis were imaged by x-ray contact microscopy using monochromatic x-rays. 6 refs., 2 figs

Bacterial actin MreB assembles in complex with cell shape protein RodZ.

Science.gov (United States)

van den Ent, Fusinita; Johnson, Christopher M; Persons, Logan; de Boer, Piet; Löwe, Jan

2010-03-17

Bacterial actin homologue MreB is required for cell shape maintenance in most non-spherical bacteria, where it assembles into helical structures just underneath the cytoplasmic membrane. Proper assembly of the actin cytoskeleton requires RodZ, a conserved, bitopic membrane protein that colocalises to MreB and is essential for cell shape determination. Here, we present the first crystal structure of bacterial actin engaged with a natural partner and provide a clear functional significance of the interaction. We show that the cytoplasmic helix-turn-helix motif of Thermotoga maritima RodZ directly interacts with monomeric as well as filamentous MreB and present the crystal structure of the complex. In vitro and in vivo analyses of mutant T. maritima and Escherichia coli RodZ validate the structure and reveal the importance of the MreB-RodZ interaction in the ability of cells to propagate as rods. Furthermore, the results elucidate how the bacterial actin cytoskeleton might be anchored to the membrane to help constrain peptidoglycan synthesis in the periplasm.

Adhesion of Spores of Bacillus thuringiensis on a Planar Surface

Energy Technology Data Exchange (ETDEWEB)

Chung, Eunhyea [Georgia Institute of Technology; Kweon, Hyojin [Georgia Institute of Technology; Yiacoumi, Sotira [Georgia Institute of Technology; Lee, Ida [University of Tennessee, Knoxville (UTK); Joy, David Charles [ORNL; Palumbo, Anthony Vito [ORNL; Tsouris, Costas [ORNL

2010-01-01

Adhesion of spores of Bacillus thuringiensis (Bt) and spherical silica particles on surfaces was experimentally and theoretically investigated in this study. Topography analysis via atomic force microscopy (AFM) and electron microscopy indicates that Bt spores are rod shaped, {approx}1.3 {mu}m in length and {approx}0.8 {mu}m in diameter. The adhesion force of Bt spores and silica particles on gold-coated glass was measured at various relative humidity (RH) levels by AFM. It was expected that the adhesion force would vary with RH because the individual force components contributing to the adhesion force depend on RH. The adhesion force between a particle and a planar surface in atmospheric environments was modeled as the contribution of three major force components: capillary, van der Waals, and electrostatic interaction forces. Adhesion force measurements for Bt spore (silica particle) and the gold surface system were comparable with calculations. Modeling results show that there is a critical RH value, which depends on the hydrophobicity of the materials involved, below which the water meniscus does not form and the contribution of the capillary force is zero. As RH increases, the van der Waals force decreases while the capillary force increases to a maximum value.

Active Tube-Shaped Actuator with Embedded Square Rod-Shaped Ionic Polymer-Metal Composites for Robotic-Assisted Manipulation

Directory of Open Access Journals (Sweden)

Yanjie Wang

2018-01-01

Full Text Available This paper reports a new technique involving the design, fabrication, and characterization of an ionic polymer-metal composite- (IPMC- embedded active tube, which can achieve multidegree-of-freedom (MODF bending motions desirable in many applications, such as a manipulator and an active catheter. However, traditional strip-type IPMC actuators are limited in only being able to generate 1-dimensional bending motion. So, in this paper, we try to develop an approach which involves molding or integrating rod-shaped IPMC actuators into a soft silicone rubber structure to create an active tube. We modified the Nafion solution casting method and developed a complete sequence of a fabrication process for rod-shaped IPMCs with square cross sections and four insulated electrodes on the surface. The silicone gel was cured at a suitable temperature to form a flexible tube using molds fabricated by 3D printing technology. By applying differential voltages to the four electrodes of each IPMC rod-shaped actuator, MDOF bending motions of the active tube can be generated. Experimental results show that such IPMC-embedded tube designs can be used for developing robotic-assisted manipulation.

Active Tube-Shaped Actuator with Embedded Square Rod-Shaped Ionic Polymer-Metal Composites for Robotic-Assisted Manipulation

Science.gov (United States)

Liu, Jiayu; Zhu, Denglin; Chen, Hualing

2018-01-01

This paper reports a new technique involving the design, fabrication, and characterization of an ionic polymer-metal composite- (IPMC-) embedded active tube, which can achieve multidegree-of-freedom (MODF) bending motions desirable in many applications, such as a manipulator and an active catheter. However, traditional strip-type IPMC actuators are limited in only being able to generate 1-dimensional bending motion. So, in this paper, we try to develop an approach which involves molding or integrating rod-shaped IPMC actuators into a soft silicone rubber structure to create an active tube. We modified the Nafion solution casting method and developed a complete sequence of a fabrication process for rod-shaped IPMCs with square cross sections and four insulated electrodes on the surface. The silicone gel was cured at a suitable temperature to form a flexible tube using molds fabricated by 3D printing technology. By applying differential voltages to the four electrodes of each IPMC rod-shaped actuator, MDOF bending motions of the active tube can be generated. Experimental results show that such IPMC-embedded tube designs can be used for developing robotic-assisted manipulation. PMID:29770160

Pulmonary infiltrates during community acquired Gram-negative bacteremia

DEFF Research Database (Denmark)

Fjeldsøe-Nielsen, Hans; Gjeraa, Kirsten; Berthelsen, Birgitte G

2013-01-01

The primary aim of this study was to describe the frequency of pulmonary infiltrates on chest X-ray (CXR) during community acquired Gram-negative bacteremia at a single centre in Denmark.......The primary aim of this study was to describe the frequency of pulmonary infiltrates on chest X-ray (CXR) during community acquired Gram-negative bacteremia at a single centre in Denmark....

Hygiene Aspects of the Biogas Process with Emphasis on Spore-Forming Bacteria

Energy Technology Data Exchange (ETDEWEB)

Bagge, Elisabeth

2009-07-01

Biogas is a renewable source of energy which can be obtained from processing of biowaste. The digested residues can be used as fertiliser. Biowaste intended for biogas production contains pathogenic micro-organisms. A pre-pasteurisation step at 70 deg C for 60 min before anaerobic digestion reduces non spore-forming bacteria such as Salmonella spp. To maintain the standard of the digested residues it must be handled in a strictly hygienic manner to avoid recontamination and re-growth of bacteria. The risk of contamination is particularly high when digested residues are transported in the same vehicles as the raw material. However, heat treatment at 70 deg C for 60 min will not reduce spore-forming bacteria such as Bacillus spp. and Clostridium spp. Spore-forming bacteria, including those that cause serious diseases, can be present in substrate intended for biogas production. The number of species and the quantity of Bacillus spp. and Clostridium spp. in manure, slaughterhouse waste and in samples from different stages during the biogas process were investigated. The number of species of clostridia seemed to decrease following digestion, likewise the quantity. However, Bacillus spp. seemed to pass unaffected through the biogas process. In laboratory-scale experiments the effects on clostridia during pasteurisation and digestion were investigated. Pathogenic clostridia were inoculated in substrates from homogenisation tanks and digester tanks. The inoculated clostridia remained after pasteurisation, but the impacts of digestion differ between different species. Culture followed by identification of C. chauvoei by PCR in samples from cattle died from blackleg, is faster and safer than culture followed by biochemical identification of C. chauvoei. However, for environmental samples the PCR method is not practically applicable for detection of C. chauvoei. To avoid spreading of diseases via biogas plants when digested residues are spread on arable land, a pasteurisation

Comparative activity of ceftobiprole against Gram-positive and Gram-negative isolates from Europe and the Middle East: the CLASS study.

Science.gov (United States)

Rossolini, Gian M; Dryden, Matthew S; Kozlov, Roman S; Quintana, Alvaro; Flamm, Robert K; Läuffer, Jörg M; Lee, Emma; Morrissey, Ian; CLASS Study Group

2011-01-01

to assess the in vitro activity of ceftobiprole and comparators against a recent collection of Gram-positive and Gram-negative pathogens, in order to detect potential changes in susceptibility patterns, and to evaluate the Etest assay for ceftobiprole susceptibility testing. contemporary Gram-positive and Gram-negative isolates (excluding extended-spectrum β-lactamase-producing isolates) from across Europe and the Middle East were collected, and their susceptibility to ceftobiprole, vancomycin, teicoplanin, linezolid, ceftazidime and cefepime was assessed using the Etest method. Quality testing [using Etest and broth microdilution (BMD)] was conducted at a central reference laboratory. some 5041 Gram-positive and 4026 Gram-negative isolates were included. Against Gram-positive isolates overall, ceftobiprole had the lowest MIC50 (0.5 mg/L), compared with 1 mg/L for its comparators (vancomycin, teicoplanin and linezolid). Against methicillin-resistant Staphylococcus aureus, all four agents had a similar MIC90 (2 mg/L), but ceftobiprole had a 4-fold better MIC90 (0.5 mg/L) against methicillin-susceptible strains. Only 38 Gram-positive isolates were confirmed as ceftobiprole resistant. Among Gram-negative strains, 86.9%, 91.7% and 95.2% were susceptible to ceftobiprole, ceftazidime and cefepime, respectively. Pseudomonas aeruginosa was less susceptible to all three antimicrobials than any other Gram-negative pathogen. There was generally good agreement between local Etest results and those obtained at the reference laboratory (for ceftobiprole: 86.8% with Gram-negatives; and 94.7% with Gram-positives), as well as between results obtained by BMD and Etest methods (for ceftobiprole: 98.2% with Gram-negatives; and 98.4% with Gram-positives). ceftobiprole exhibits in vitro activity against a wide range of Gram-positive and Gram-negative pathogens, including multidrug-resistant strains. No changes in its known susceptibility profile were identified.

Jeotgalibacillus soli sp. nov., a Gram-stain-positive bacterium isolated from soil.

Science.gov (United States)

Cunha, Sofia; Tiago, Igor; Paiva, Gabriel; Nobre, Fernanda; da Costa, Milton S; Veríssimo, António

2012-03-01

A Gram-staining-positive, motile, rod-shaped, spore-forming bacterium, designated P9(T), was isolated from soil in Portugal. This organism was aerobic and catalase- and oxidase-positive. It had an optimum growth temperature of about 35 °C and an optimum growth pH of about 8.0-8.5, and grew in medium with 0-9% (w/v) NaCl. The cell-wall peptidoglycan was of the A1α type, with L-lysine as the diagnostic diamino acid. The major respiratory quinone was menaquinone 7 (MK-7) and the major fatty acids were anteiso-C(15:0) (45.4%), iso-C(15:0) (22.0%) and anteiso-C(17:0) (11.2%). The genomic DNA G+C content was about 39.4 mol%. Phylogenetic analysis based on 16S rRNA gene sequences indicated that strain P9(T) was most closely related to Jeotgalibacillus campisalis DSM 18983(T) (96.8%) and Jeotgalibacillus marinus DSM 1297(T) (96.5%). These two recognized species formed a coherent cluster with strain P9(T) that was supported by a bootstrap value of 99%. On the basis of the phylogenetic analysis and physiological and biochemical characteristics, strain P9(T) (=DSM 23228(T)=LMG 25523(T)) represents a novel species of the genus Jeotgalibacillus, for which the name Jeotgalibacillus soli sp. nov. is proposed.

Prediction of lipoprotein signal peptides in Gram-negative bacteria.

Science.gov (United States)

Juncker, Agnieszka S; Willenbrock, Hanni; Von Heijne, Gunnar; Brunak, Søren; Nielsen, Henrik; Krogh, Anders

2003-08-01

A method to predict lipoprotein signal peptides in Gram-negative Eubacteria, LipoP, has been developed. The hidden Markov model (HMM) was able to distinguish between lipoproteins (SPaseII-cleaved proteins), SPaseI-cleaved proteins, cytoplasmic proteins, and transmembrane proteins. This predictor was able to predict 96.8% of the lipoproteins correctly with only 0.3% false positives in a set of SPaseI-cleaved, cytoplasmic, and transmembrane proteins. The results obtained were significantly better than those of previously developed methods. Even though Gram-positive lipoprotein signal peptides differ from Gram-negatives, the HMM was able to identify 92.9% of the lipoproteins included in a Gram-positive test set. A genome search was carried out for 12 Gram-negative genomes and one Gram-positive genome. The results for Escherichia coli K12 were compared with new experimental data, and the predictions by the HMM agree well with the experimentally verified lipoproteins. A neural network-based predictor was developed for comparison, and it gave very similar results. LipoP is available as a Web server at www.cbs.dtu.dk/services/LipoP/.

Raman Spectroscopy of Xylitol Uptake and Metabolism in Gram-Positive and Gram-Negative Bacteria▿

Science.gov (United States)

Palchaudhuri, Sunil; Rehse, Steven J.; Hamasha, Khozima; Syed, Talha; Kurtovic, Eldar; Kurtovic, Emir; Stenger, James

2011-01-01

Visible-wavelength Raman spectroscopy was used to investigate the uptake and metabolism of the five-carbon sugar alcohol xylitol by Gram-positive viridans group streptococcus and the two extensively used strains of Gram-negative Escherichia coli, E. coli C and E. coli K-12. E. coli C, but not E. coli K-12, contains a complete xylitol operon, and the viridans group streptococcus contains an incomplete xylitol operon used to metabolize the xylitol. Raman spectra from xylitol-exposed viridans group streptococcus exhibited significant changes that persisted even in progeny grown from the xylitol-exposed mother cells in a xylitol-free medium for 24 h. This behavior was not observed in the E. coli K-12. In both viridans group streptococcus and the E. coli C derivative HF4714, the metabolic intermediates are stably formed to create an anomaly in bacterial normal survival. The uptake of xylitol by Gram-positive and Gram-negative pathogens occurs even in the presence of other high-calorie sugars, and its stable integration within the bacterial cell wall may discontinue bacterial multiplication. This could be a contributing factor for the known efficacy of xylitol when taken as a prophylactic measure to prevent or reduce occurrences of persistent infection. Specifically, these bacteria are causative agents for several important diseases of children such as pneumonia, otitis media, meningitis, and dental caries. If properly explored, such an inexpensive and harmless sugar-alcohol, alone or used in conjunction with fluoride, would pave the way to an alternative preventive therapy for these childhood diseases when the causative pathogens have become resistant to modern medicines such as antibiotics and vaccine immunotherapy. PMID:21037297

Long helical filaments are not seen encircling cells in electron cryotomograms of rod-shaped bacteria

International Nuclear Information System (INIS)

Swulius, Matthew T.; Chen, Songye; Jane Ding, H.; Li, Zhuo; Briegel, Ariane; Pilhofer, Martin; Tocheva, Elitza I.; Lybarger, Suzanne R.; Johnson, Tanya L.; Sandkvist, Maria; Jensen, Grant J.

2011-01-01

Highlights: → No long helical filaments are seen near or along rod-shaped bacterial inner membranes by electron cryo-tomography. → Electron cryo-tomography has the resolution to detect single filaments in vivo. -- Abstract: How rod-shaped bacteria form and maintain their shape is an important question in bacterial cell biology. Results from fluorescent light microscopy have led many to believe that the actin homolog MreB and a number of other proteins form long helical filaments along the inner membrane of the cell. Here we show using electron cryotomography of six different rod-shaped bacterial species, at macromolecular resolution, that no long (>80 nm) helical filaments exist near or along either surface of the inner membrane. We also use correlated cryo-fluorescent light microscopy (cryo-fLM) and electron cryo-tomography (ECT) to identify cytoplasmic bundles of MreB, showing that MreB filaments are detectable by ECT. In light of these results, the structure and function of MreB must be reconsidered: instead of acting as a large, rigid scaffold that localizes cell-wall synthetic machinery, moving MreB complexes may apply tension to growing peptidoglycan strands to ensure their orderly, linear insertion.

Combinatorial events of insertion sequences and ICE in Gram-negative bacteria.

Science.gov (United States)

Toleman, Mark A; Walsh, Timothy R

2011-09-01

The emergence of antibiotic and antimicrobial resistance in Gram-negative bacteria is incremental and linked to genetic elements that function in a so-called 'one-ended transposition' manner, including ISEcp1, ISCR elements and Tn3-like transposons. The power of these elements lies in their inability to consistently recognize one of their own terminal sequences, while recognizing more genetically distant surrogate sequences. This has the effect of mobilizing the DNA sequence found adjacent to their initial location. In general, resistance in Gram-negatives is closely linked to a few one-off events. These include the capture of the class 1 integron by a Tn5090-like transposon; the formation of the 3' conserved segment (3'-CS); and the fusion of the ISCR1 element to the 3'-CS. The structures formed by these rare events have been massively amplified and disseminated in Gram-negative bacteria, but hitherto, are rarely found in Gram-positives. Such events dominate current resistance gene acquisition and are instrumental in the construction of large resistance gene islands on chromosomes and plasmids. Similar combinatorial events appear to have occurred between conjugative plasmids and phages constructing hybrid elements called integrative and conjugative elements or conjugative transposons. These elements are beginning to be closely linked to some of the more powerful resistance mechanisms such as the extended spectrum β-lactamases, metallo- and AmpC type β-lactamases. Antibiotic resistance in Gram-negative bacteria is dominated by unusual combinatorial mistakes of Insertion sequences and gene fusions which have been selected and amplified by antibiotic pressure enabling the formation of extended resistance islands. © 2011 Federation of European Microbiological Societies. Published by Blackwell Publishing Ltd. All rights reserved.

Low antibiotic resistance among anaerobic Gram-negative bacteria in periodontitis 5 years following metronidazole therapy.

Science.gov (United States)

Dahlen, G; Preus, H R

2017-02-01

The objective of this study was to assess antibiotic susceptibility among predominant Gram-negative anaerobic bacteria isolated from periodontitis patients who 5 years prior had been subject to mechanical therapy with or without adjunctive metronidazole. One pooled sample was taken from the 5 deepest sites of each of 161 patients that completed the 5 year follow-up after therapy. The samples were analyzed by culture. A total number of 85 anaerobic strains were isolated from the predominant subgingival flora of 65/161 patient samples, identified, and tested for antibiotic susceptibility by MIC determination. E-tests against metronidazole, penicillin, amoxicillin, amoxicillin + clavulanic acid and clindamycin were employed. The 73/85 strains were Gram-negative rods (21 Porphyromonas spp., 22 Prevotella/Bacteroides spp., 23 Fusobacterium/Filifactor spp., 3 Campylobacter spp. and 4 Tannerella forsythia). These were all isolated from the treated patients irrespective of therapy procedures (+/-metronidazole) 5 years prior. Three strains (Bifidobacterium spp., Propionibacterium propionicum, Parvimonas micra) showed MIC values for metronidazole over the European Committee on Antimicrobial Susceptibility Testing break point of >4 μg/mL. All Porphyromonas and Tannerella strains were highly susceptible. Metronidazole resistant Gram-negative strains were not found, while a few showed resistance against beta-lactam antibiotics. In this population of 161 patients who had been subject to mechanical periodontal therapy with or without adjunct metronidazole 5 years prior, no cultivable antibiotic resistant anaerobes were found in the predominant subgingival microbiota. Copyright © 2016 Elsevier Ltd. All rights reserved.

Bacillus nealsonii sp. nov., isolated from a spacecraft-assembly facility, whose spores are gamma-radiation resistant

Science.gov (United States)

Venkateswaran, Kasthuri; Kempf, Michael; Chen, Fei; Satomi, Masataka; Nicholson, Wayne; Kern, Roger

2003-01-01

One of the spore-formers isolated from a spacecraft-assembly facility, belonging to the genus Bacillus, is described on the basis of phenotypic characterization, 16S rDNA sequence analysis and DNA-DNA hybridization studies. It is a Gram-positive, facultatively anaerobic, rod-shaped eubacterium that produces endospores. The spores of this novel bacterial species exhibited resistance to UV, gamma-radiation, H2O2 and desiccation. The 18S rDNA sequence analysis revealed a clear affiliation between this strain and members of the low G+C Firmicutes. High 16S rDNA sequence similarity values were found with members of the genus Bacillus and this was supported by fatty acid profiles. The 16S rDNA sequence similarity between strain FO-92T and Bacillus benzoevorans DSM 5391T was very high. However, molecular characterizations employing small-subunit 16S rDNA sequences were at the limits of resolution for the differentiation of species in this genus, but DNA-DNA hybridization data support the proposal of FO-92T as Bacillus nealsonii sp. nov. (type strain is FO-92T =ATCC BAAM-519T =DSM 15077T).

Protamine-induced permeabilization of cell envelopes of gram-positive and gram-negative bacteria

DEFF Research Database (Denmark)

Johansen, Charlotte; Verheul, A.; Gram, Lone

1997-01-01

carboxyfluorescein and ATP after 2 to 5 min. Maximum antibacterial activity was reached at alkaline pH and in the absence of divalent cations. The efficient permeabilization of cell envelopes of both gram-positive and gram-negative bacteria suggests that protamine causes a general disruption of the cell envelope...

Morphogenesis of rod-shaped sacculi

NARCIS (Netherlands)

den Blaauwen, T.; de Pedro, M.A.; Nguyen-Distèche, M.; Ayala, J.A.

2008-01-01

For growth and division of rod-shaped bacteria, the cylindrical part of the sacculus has to be elongated and two new cell poles have to be synthesized. The elongation is performed by a protein complex, the elongase that inserts disaccharidepentapeptide units at a limited number of discrete sites

Extended spectrum β-lactamases, carbapenemases and mobile genetic elements responsible for antibiotics resistance in Gram-negative bacteria.

Science.gov (United States)

El Salabi, Allaaeddin; Walsh, Timothey R; Chouchani, Chedly

2013-05-01

Infectious diseases due to Gram-negative bacteria are a leading cause of morbidity and mortality worldwide. Antimicrobial agents represent one major therapeutic tools implicated to treat these infections. The misuse of antimicrobial agents has resulted in the emergence of resistant strains of Gram-negatives in particular Enterobacteriaceae and non-fermenters; they have an effect not only on a human but on the public health when bacteria use the resistance mechanisms to spread in the hospital environment and to the community outside the hospitals by means of mobile genetic elements. Gram-negative bacteria have become increasingly resistant to antimicrobial agents. They have developed several mechanisms by which they can withstand to antimicrobials, these mechanisms include the production of Extended-spectrum β-lactamases (ESBLs) and carbapenemases, furthermore, Gram-negative bacteria are now capable of spreading such resistance between members of the family Enterobacteriaceae and non-fermenters using mobile genetic elements as vehicles for such resistance mechanisms rendering antibiotics useless. Therefore, addressing the issue of mechanisms of antimicrobial resistance is considered one of most urgent priorities. This review will help to illustrate different resistance mechanisms; ESBLs, carbapenemases encoded by genes carried by mobile genetic elements, which are used by Gram-negative bacteria to escape antimicrobial effect.

Thermophilic bacteria in Moroccan hot springs, salt marshes and desert soils

OpenAIRE

Aanniz,Tarik; Ouadghiri,Mouna; Melloul,Marouane; Swings,Jean; Elfahime,Elmostafa; Ibijbijen,Jamal; Ismaili,Mohamed; Amar,Mohamed

2015-01-01

The diversity of thermophilic bacteria was investigated in four hot springs, three salt marshes and 12 desert sites in Morocco. Two hundred and forty (240) thermophilic bacteria were recovered, identified and characterized. All isolates were Gram positive, rod-shaped, spore forming and halotolerant. Based on BOXA1R-PCR and 16S rRNA gene sequencing, the recovered isolates were dominated by the genus Bacillus (97.5%) represented by B. licheniformis (119), B. aerius (44), B. sonorensis (33), B. ...

Organo-Selenium Coatings Inhibit Gram-Negative and Gram-Positive Bacterial Attachment to Ophthalmic Scleral Buckle Material.

Science.gov (United States)

Tran, Phat; Arnett, Avery; Jarvis, Courtney; Mosley, Thomas; Tran, Khien; Hanes, Rob; Webster, Dan; Mitchell, Kelly; Dominguez, Leo; Hamood, Abdul; Reid, Ted W

2017-09-01

Biofilm formation is a problem for solid and sponge-type scleral buckles. This can lead to complications that require removal of the buckle, and result in vision loss due to related ocular morbidity, primarily infection, or recurrent retinal detachment. We investigate the ability of a covalent organo-selenium coating to inhibit biofilm formation on a scleral buckle. Sponge and solid Labtican brand scleral buckles were coated with organo-selenium coupled to a silyation reagent. Staphylococcus aureus biofilm formation was monitored by a standard colony-forming unit assay and the confocal laser scanning microscopy, while Pseudomonas aeruginosa biofilm formation was examined by scanning electron microscopy. Stability studies were done, by soaking in phosphate buffer saline (PBS) at room temperature for 2 months. Toxicity against human corneal epithelial cell was examined by growing the cells in the presence of organo-selenium-coated scleral buckles. The organo-selenium coating inhibited biofilm formation by gram-negative and gram-positive bacteria. The buckle coatings also were shown to be fully active after soaking in PBS for 2 months. The organo-selenium coatings had no effect on the viability of human corneal epithelial cells. Organo-selenium can be used to covalently coat a scleral buckle, which is stable and inhibits biofilm formation for gram-negative and gram-positive bacteria. The organo-selenium buckle coating was stable and nontoxic to cell culture. This technology provides a means to inhibit bacterial attachment to devices attached to the eye, without damage to ocular cells.

Amplifiable DNA from Gram-negative and Gram-positive bacteria by a low strength pulsed electric field method

Science.gov (United States)

Vitzthum, Frank; Geiger, Georg; Bisswanger, Hans; Elkine, Bentsian; Brunner, Herwig; Bernhagen, Jürgen

2000-01-01

An efficient electric field-based procedure for cell disruption and DNA isolation is described. Isoosmotic suspensions of Gram-negative and Gram-positive bacteria were treated with pulsed electric fields of Pulses had an exponential decay waveform with a time constant of 3.4 µs. DNA yield was linearly dependent on time or pulse number, with several thousand pulses needed. Electrochemical side-effects and electrophoresis were minimal. The lysates contained non-fragmented DNA which was readily amplifiable by PCR. As the method was not limited to samples of high specific resistance, it should be applicable to physiological fluids and be useful for genomic and DNA diagnostic applications. PMID:10734214

Is Longitudinal Division in Rod-Shaped Bacteria a Matter of Swapping Axis?

Directory of Open Access Journals (Sweden)

Tanneke den Blaauwen

2018-05-01

Full Text Available The morphology of bacterial species shows a wealth of variation from star-shaped to spherical and rod- to spiral-shaped, to mention a few. Their mode of growth and division is also very diverse and flexible ranging from polar growth and lateral surface increase to midcell expansion and from perpendicular to longitudinal asymmetric division. Gammaproteobacterial rod-shaped species such as Escherchia coli divide perpendicularly and grow in length, whereas the genetically very similar rod-shaped symbiotic Thiosymbion divide longitudinally, and some species even divide asynchronously while growing in width. The ovococcal Streptococcus pneumoniae also lengthens and divides perpendicularly, yet it is genetically very different from E. coli. Are these differences as dramatic as is suggested by visual inspection, or can they all be achieved by subtle variation in the regulation of the same protein complexes that synthesize the cell envelope? Most bacteria rely on the cytoskeletal polymer FtsZ to organize cell division, but only a subset of species use the actin homolog MreB for length growth, although some of them are morphologically not that different. Poles are usually negative determinant for cell division. Curved cell poles can be inert or active with respect to peptidoglycan synthesis, can localize chemotaxis and other sensing proteins or other bacterial equipment, such as pili, depending on the species. But what is actually the definition of a pole? This review discusses the possible common denominators for growth and division of distinct and similar bacterial species.

Antimicrobial Activity of Carbon Nanoparticles Isolated from Natural Sources against Pathogenic Gram-Negative and Gram-Positive Bacteria

International Nuclear Information System (INIS)

Varghese, S.; Jose, S.; Varghese, S.; Kuriakose, S.; Jose, S.

2013-01-01

This paper describes the isolation of carbon nanoparticles (CNPs) from kitchen soot, characterization of the CNPs by UV/visible spectroscopy, SEM and XRD, and their antimicrobial action. The antibacterial activity of the isolated carbon nanoparticles was tested against various pathogenic bacterial strains such as Gram-negative Proteus refrigere and Pseudomonas aeruginosa and Gram-positive Staphylococcus aureus and Streptococcus haemolyticus. The inhibition zones were measured, and it was found that the carbon nanoparticles isolated from natural sources are active against these Gram-negative and Gram-positive bacterial strains

Handling technique of spore-forming bacteria in radiation sterilization. 2. Determination of numbers and radiation resistance of spores

International Nuclear Information System (INIS)

Koshikawa, Tomihiko

1994-01-01

Stepwise ten-fold dilution of bacterial solution is required in the determination of bacterial spores. For this, the selection of diluted solution is important according to the purpose of experiment. First, the preparation of suspension of bacterial spores and selection of diluted solution are presented. Then, a method for determining the number of bacterial spores in materials is outlined in terms of dilution methods of bacterial solution (shaking and homogenization) and application method of diluted solution to the plating medium. Finally, a method for determining radiation resistance of spore-forming bacteria is explained according to the measurement conditions (suspension of bacterial spores and filters applied with bacterial spores). (N.K.)

Handling technique of spore-forming bacteria in radiation sterilization. 2. Determination of numbers and radiation resistance of spores

Energy Technology Data Exchange (ETDEWEB)

Koshikawa, Tomihiko [Japan Radioisotope Association, Shiga (Japan). Koka Laboratory

1994-12-01

Stepwise ten-fold dilution of bacterial solution is required in the determination of bacterial spores. For this, the selection of diluted solution is important according to the purpose of experiment. First, the preparation of suspension of bacterial spores and selection of diluted solution are presented. Then, a method for determining the number of bacterial spores in materials is outlined in terms of dilution methods of bacterial solution (shaking and homogenization) and application method of diluted solution to the plating medium. Finally, a method for determining radiation resistance of spore-forming bacteria is explained according to the measurement conditions (suspension of bacterial spores and filters applied with bacterial spores). (N.K.).

Localization of Low Copy Number Plasmid pRC4 in Replicating Rod and Non-Replicating Cocci Cells of Rhodococcus erythropolis PR4.

Directory of Open Access Journals (Sweden)

Divya Singhi

Full Text Available Rhodococcus are gram-positive bacteria, which can exist in two different shapes rod and cocci. A number of studies have been done in the past on replication and stability of small plasmids in this bacterium; however, there are no reports on spatial localization and segregation of these plasmids. In the present study, a low copy number plasmid pDS3 containing pRC4 replicon was visualized in growing cells of Rhodococcus erythropolis PR4 (NBRC100887 using P1 parS-ParB-GFP system. Cells were initially cocci and then became rod shaped in exponential phase. Cocci cells were found to be non-replicating as evident by the presence of single fluorescence focus corresponding to the plasmid and diffuse fluorescence of DnaB-GFP. Rod shaped cells contained plasmid either present as one fluorescent focus observed at the cell center or two foci localized at quarter positions. The results suggest that the plasmid is replicated at the cell center and then it goes to quarter position. In order to observe the localization of plasmid with respect to nucleoid, plasmid segregation was also studied in filaments where it was found to be replicated at the cell center in a nucleoid free region. To the best of our knowledge, this is the first report on segregation of small plasmids in R. erythropolis.

Potential strategies for the eradication of multidrug-resistant Gram-negative bacterial infections.

Science.gov (United States)

Huwaitat, Rawan; McCloskey, Alice P; Gilmore, Brendan F; Laverty, Garry

2016-07-01

Antimicrobial resistance is one of the leading threats to society. The increasing burden of multidrug-resistant Gram-negative infection is particularly concerning as such bacteria are demonstrating resistance to nearly all currently licensed therapies. Various strategies have been hypothesized to treat multidrug-resistant Gram-negative infections including: targeting the Gram-negative outer membrane; neutralization of lipopolysaccharide; inhibition of bacterial efflux pumps and prevention of protein folding. Silver and silver nanoparticles, fusogenic liposomes and nanotubes are potential strategies for extending the activity of licensed, Gram-positive selective, antibiotics to Gram-negatives. This may serve as a strategy to fill the current void in pharmaceutical development in the short term. This review outlines the most promising strategies that could be implemented to solve the threat of multidrug-resistant Gram-negative infections.

Xanthomarina gelatinilytica gen nov., sp nov., isolated from seawater

Digital Repository Service at National Institute of Oceanography (India)

Bhumika, V.; Ravinder, K.; Sharma, G.; Srinivas, T.N.R.; AnilKumar, P.

A novel Gram-stain-negative, rod-shaped, yellow-pigmented, non-sporulating, non-motile bacterium, designated strain AK20^T, was isolated from seawater collected from Kochi city, Kerala state, India Colonies on marine agar were circular...

Will new antimicrobials overcome resistance among Gram-negatives?

Science.gov (United States)

Bassetti, Matteo; Ginocchio, Francesca; Mikulska, Małgorzata; Taramasso, Lucia; Giacobbe, Daniele Roberto

2011-10-01

The spread of resistance among Gram-positive and Gram-negative bacteria represents a growing challenge for the development of new antimicrobials. The pace of antibiotic drug development has slowed during the last decade and, especially for Gram-negatives, clinicians are facing a dramatic shortage in the availability of therapeutic options to face the emergency of the resistance problem throughout the world. In this alarming scenario, although there is a shortage of compounds reaching the market in the near future, antibiotic discovery remains one of the keys to successfully stem and maybe overcome the tide of resistance. Analogs of already known compounds and new agents belonging to completely new classes of antimicrobials are in early stages of development. Novel and promising anti-Gram-negative antimicrobials belong both to old (cephalosporins, carbapenems, β-lactamase inhibitors, monobactams, aminoglycosides, polymyxin analogues and tetracycline) and completely new antibacterial classes (boron-containing antibacterial protein synthesis inhibitors, bis-indoles, outer membrane synthesis inhibitors, antibiotics targeting novel sites of the 50S ribosomal subunit and antimicrobial peptides). However, all of these compounds are still far from being introduced into clinical practice. Therefore, infection control policies and optimization in the use of already existing molecules are still the most effective approaches to reduce the spread of resistance and preserve the activity of antimicrobials.

Revisiting the gram-negative lipoprotein paradigm

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The processing of lipoproteins (lpps) in Gram-negative bacteria is generally considered to be an essential pathway. Mature lipoproteins in these bacteria are triacylated, with the final fatty acid addition performed by Lnt, an apolipoprotein n-acyltransferase. The mature lipoproteins are then sorted...

Indole and 3-indolylacetonitrile inhibit spore maturation in Paenibacillus alvei

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Cho Moo

2011-05-01

Full Text Available Abstract Background Bacteria use diverse signaling molecules to ensure the survival of the species in environmental niches. A variety of both Gram-positive and Gram-negative bacteria produce large quantities of indole that functions as an intercellular signal controlling diverse aspects of bacterial physiology. Results In this study, we sought a novel role of indole in a Gram-positive bacteria Paenibacillus alvei that can produce extracellular indole at a concentration of up to 300 μM in the stationary phase in Luria-Bertani medium. Unlike previous studies, our data show that the production of indole in P. alvei is strictly controlled by catabolite repression since the addition of glucose and glycerol completely turns off the indole production. The addition of exogenous indole markedly inhibits the heat resistance of P. alvei without affecting cell growth. Observation of cell morphology with electron microscopy shows that indole inhibits the development of spore coats and cortex in P. alvei. As a result of the immature spore formation of P. alvei, indole also decreases P. alvei survival when exposed to antibiotics, low pH, and ethanol. Additionally, indole derivatives also influence the heat resistance; for example, a plant auxin, 3-indolylacetonitrile dramatically (2900-fold decreased the heat resistance of P. alvei, while another auxin 3-indoleacetic acid had a less significant influence on the heat resistance of P. alvei. Conclusions Together, our results demonstrate that indole and plant auxin 3-indolylacetonitrile inhibit spore maturation of P. alvei and that 3-indolylacetonitrile presents an opportunity for the control of heat and antimicrobial resistant spores of Gram-positive bacteria.

Imtechella halotolerans gen. nov., sp. nov., a member of the family Flavobacteriaceae isolated from estuarine water

Digital Repository Service at National Institute of Oceanography (India)

Surendra, V.; Bhawana, P.; Suresh, K.; Srinivas, T.N.R.; AnilKumar, P.

A novel Gram-negative, rod-shaped, non-motile, non-sporulating bacterium, designated strain K1 sup(T), was isolated from an estuarine water sample collected from Kochi, Kerala, India. Colonies on marine agar were circular, 2.0-2.5 mm in diameter...

Outcomes of single organism peritonitis in peritoneal dialysis: gram negatives versus gram positives in the Network 9 Peritonitis Study.

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Bunke, C M; Brier, M E; Golper, T A

1997-08-01

The use of the "peritonitis rate" in the management of patients undergoing peritoneal dialysis is assuming importance in comparing the prowess of facilities, care givers and new innovations. For this to be a meaningful outcome measure, the type of infection (causative pathogen) must have less clinical significance than the number of infections during a time interval. The natural history of Staphylococcus aureus, pseudomonas, and fungal peritonitis would not support that the outcome of an episode of peritonitis is independent of the causative pathogen. Could this concern be extended to other more frequently occurring pathogens? To address this, the Network 9 Peritonitis Study identified 530 episodes of single organism peritonitis caused by a gram positive organism and 136 episodes caused by a single non-pseudomonal gram negative (NPGN) pathogen. Coincidental soft tissue infections (exit site or tunnel) occurred equally in both groups. Outcomes of peritonitis were analyzed by organism classification and by presence or absence of a soft tissue infection. NPGN peritonitis was associated with significantly more frequent catheter loss, hospitalization, and technique failure and was less likely to resolve regardless of the presence or absence of a soft tissue infection. Hospitalization and death tended to occur more frequently with enterococcal peritonitis than with other gram positive peritonitis. The outcomes in the NPGN peritonitis group were significantly worse (resolution, catheter loss, hospitalization, technique failure) compared to coagulase negative staphylococcal or S. aureus peritonitis, regardless of the presence or absence of a coincidental soft tissue infection. Furthermore, for the first time, the poor outcomes of gram negative peritonitis are shown to be independent of pseudomonas or polymicrobial involvement or soft tissue infections. The gram negative organism appears to be the important factor. In addition, the outcome of peritonitis caused by S. aureus

Colonization of long term care facility patients with MDR-Gram-negatives during an Acinetobacter baumannii outbreak

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Ines Zollner-Schwetz

2017-05-01

Full Text Available Abstract Background We aimed to determine the prevalence of colonization by multidrug-resistant Gram-negative bacteria including ESBL-producing enterobacteriaceae, carbapenem-resistant enterobacteriaceae, Pseudomonas aeruginosa and Acinetobacter baumannii at two wards caring long term for patients with disorder of consciousness at the Geriatric Health Centers Graz, Austria. During our study we detected two A. baumannii outbreaks. Methods In August 2015, we conducted a point-prevalence study. Inguinal and perianal swabs were taken from 38 patients and screened for multidrug-resistant Gram-negative rods using standard procedures. Six months after the initial investigation all patients were sampled again and use of antibiotics during the past 6 months and mortality was registered. Genetic relatedness of bacteria was evaluated by DiversiLab system. Results Fifty percent of patients were colonized by multidrug-resistant Gram-negative isolates. Five patients harboured ESBL-producing enterobacteriaceae. No carbapenem-resistant enterobacteriaceae were detected. 13/38 patients were colonized by A. baumannii isolates (resistant to ciprofloxacin but susceptible to carbapenems. There was a significant difference in the prevalence of colonization by A. baumannii between ward 2 and ward 1 (60% vs. 5.6%, p < 0.001. Two clusters of A. baumannii isolates were identified including one isolate detected on a chair in a patient’s room. Conclusions We detected a high prevalence of two multidrug-resistant A. baumannii strains in patients with disorder of consciousness at a LTCF in Graz, Austria. Our findings strongly suggest nosocomial cross-transmission between patients. An active surveillance strategy is warranted to avoid missing newly emerging pathogens.

Colonization of long term care facility patients with MDR-Gram-negatives during an Acinetobacter baumannii outbreak.

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Zollner-Schwetz, Ines; Zechner, Elisabeth; Ullrich, Elisabeth; Luxner, Josefa; Pux, Christian; Pichler, Gerald; Schippinger, Walter; Krause, Robert; Leitner, Eva

2017-01-01

We aimed to determine the prevalence of colonization by multidrug-resistant Gram-negative bacteria including ESBL-producing enterobacteriaceae, carbapenem-resistant enterobacteriaceae, Pseudomonas aeruginosa and Acinetobacter baumannii at two wards caring long term for patients with disorder of consciousness at the Geriatric Health Centers Graz, Austria. During our study we detected two A. baumannii outbreaks. In August 2015, we conducted a point-prevalence study. Inguinal and perianal swabs were taken from 38 patients and screened for multidrug-resistant Gram-negative rods using standard procedures. Six months after the initial investigation all patients were sampled again and use of antibiotics during the past 6 months and mortality was registered. Genetic relatedness of bacteria was evaluated by DiversiLab system. Fifty percent of patients were colonized by multidrug-resistant Gram-negative isolates. Five patients harboured ESBL-producing enterobacteriaceae. No carbapenem-resistant enterobacteriaceae were detected. 13/38 patients were colonized by A. baumannii isolates (resistant to ciprofloxacin but susceptible to carbapenems). There was a significant difference in the prevalence of colonization by A. baumannii between ward 2 and ward 1 (60% vs. 5.6%, p  < 0.001). Two clusters of A. baumannii isolates were identified including one isolate detected on a chair in a patient's room. We detected a high prevalence of two multidrug-resistant A. baumannii strains in patients with disorder of consciousness at a LTCF in Graz, Austria. Our findings strongly suggest nosocomial cross-transmission between patients. An active surveillance strategy is warranted to avoid missing newly emerging pathogens.

Adaptation of the spore discharge mechanism in the basidiomycota.

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Jessica L Stolze-Rybczynski

Full Text Available Spore discharge in the majority of the 30,000 described species of Basidiomycota is powered by the rapid motion of a fluid droplet, called Buller's drop, over the spore surface. In basidiomycete yeasts, and phytopathogenic rusts and smuts, spores are discharged directly into the airflow around the fungal colony. Maximum discharge distances of 1-2 mm have been reported for these fungi. In mushroom-forming species, however, spores are propelled over much shorter ranges. In gilled mushrooms, for example, discharge distances of <0.1 mm ensure that spores do not collide with opposing gill surfaces. The way in which the range of the mechanism is controlled has not been studied previously.In this study, we report high-speed video analysis of spore discharge in selected basidiomycetes ranging from yeasts to wood-decay fungi with poroid fruiting bodies. Analysis of these video data and mathematical modeling show that discharge distance is determined by both spore size and the size of the Buller's drop. Furthermore, because the size of Buller's drop is controlled by spore shape, these experiments suggest that seemingly minor changes in spore morphology exert major effects upon discharge distance.This biomechanical analysis of spore discharge mechanisms in mushroom-forming fungi and their relatives is the first of its kind and provides a novel view of the incredible variety of spore morphology that has been catalogued by traditional taxonomists for more than 200 years. Rather than representing non-selected variations in micromorphology, the new experiments show that changes in spore architecture have adaptive significance because they control the distance that the spores are shot through air. For this reason, evolutionary modifications to fruiting body architecture, including changes in gill separation and tube diameter in mushrooms, must be tightly linked to alterations in spore morphology.

Cytokine profile in severe gram-positive and gram-negative abdominal sepsis

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Surbatovic, Maja; Popovic, Nada; Vojvodic, Danilo; Milosevic, Ivan; Acimovic, Gordana; Stojicic, Milan; Veljovic, Milic; Jevdjic, Jasna; Djordjevic, Dragan; Radakovic, Sonja

2015-01-01

Sepsis is a principal cause of death in critical care units worldwide and consumes considerable healthcare resources. The aim of our study was to determine whether the early cytokine profile can discriminate between Gram-positive and Gram-negative bacteraemia (GPB and GNB, respectively) and to assess the prognostic value regarding outcome in critically ill patients with severe abdominal sepsis. The outcome measure was hospital mortality. Blood samples were obtained from 165 adult patients with confirmed severe abdominal sepsis. Levels of the proinflammatory mediators TNF-α, IL-8, IL-12 and IFN-γ and the anti-inflammatory mediators IL-1ra, IL-4, IL-10 and TGF-β1 were determined and correlated with the nature of the bacteria isolated from the blood culture and outcome. The cytokine profile in our study indicated that the TNF-α levels were 2-fold, IL-8 were 3.3-fold, IFN-γ were 13-fold, IL-1ra were 1.05-fold, IL-4 were 1.4-fold and IL-10 were 1.83-fold higher in the GNB group compared with the GPB group. The TNF-α levels were 4.7-fold, IL-8 were 4.6-fold, IL-1ra were 1.5-fold and IL-10 were 3.3-fold higher in the non-survivors compared with the survivors. PMID:26079127

Expansion of highly stable bla OXA-10 β-lactamase family within diverse host range among nosocomial isolates of Gram-negative bacilli within a tertiary referral hospital of Northeast India.

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Maurya, Anand Prakash; Dhar, Debadatta; Basumatary, Mridul Kumar; Paul, Deepjyoti; Ingti, Birson; Choudhury, Debarati; Talukdar, Anupam Das; Chakravarty, Atanu; Mishra, Shweta; Bhattacharjee, Amitabha

2017-04-04

The current study reports dissemination of highly stable bla OXA-10 family of beta lactamases among diverse group of nosocomial isolates of Gram-negative bacilli within a tertiary referral hospital of the northern part of India. In the current study, a total number of 590 Gram negative isolates were selected for a period of 1 year (i.e. 1st November 2011-31st October 2012). Members of Enterobacteriaceae and non fermenting Gram negative rods were obtained from Silchar Medical College and Hospital, Silchar, India. Screening and molecular characterization of β-lactamase genes was done. Integrase gene PCR was performed for detection and characterization of integrons and cassette PCR was performed for study of the variable regions of integron gene cassettes carrying bla OXA-10 . Gene transferability, stability and replicon typing was also carried out. Isolates were typed by ERIC as well as REP PCR. Twenty-four isolates of Gram-negative bacilli that were harboring bla OXA-10 family (OXA-14, and OXA16) with fact that resistance was to the extended cephalosporins. The resistance determinant was located within class I integron in five diverse genetic contexts and horizontally transferable in Enterobacteriaceae, was carried through IncY type plasmid. MIC values were above break point for all the tested cephalosporins. Furthermore, co-carriage of bla CMY-2 was also observed. Multiple genetic environment of bla OXA-10 in this geographical region must be investigated to prevent dissemination of these gene cassettes within bacterial population within hospital settings.

Risk factors for multidrug-resistant Gram-negative infection in burn patients.

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Vickers, Mark L; Dulhunty, Joel M; Ballard, Emma; Chapman, Paul; Muller, Michael; Roberts, Jason A; Cotta, Menino O

2018-05-01

Infection with multidrug-resistant (MDR) Gram-negative organisms leads to poorer outcomes in the critically ill burn patient. The aim of this study was to identify the risk factors for MDR Gram-negative pathogen infection in critically ill burn patients admitted to a major tertiary referral intensive care unit (ICU) in Australia. A retrospective case-control study of all adult burn patients admitted over a 7-year period was conducted. Twenty-one cases that cultured an MDR Gram-negative organism were matched with 21 controls of similar age, gender, burn size and ICU stay. Multivariable conditional logistic regression was used to individually assess risk factors after adjusting for Acute Burn Severity Index. Adjusted odds ratios (ORs) were reported. P-values negative infection included superficial partial thickness burn size (OR: 1.08; 95% confidence interval (CI): 1.01-1.16; P-value: 0.034), prior meropenem exposure (OR: 10.39; 95% CI: 0.96-112.00; P-value: 0.054), Gram-negative colonization on admission (OR: 9.23; 95% CI: 0.65-130.15; P-value: 0.10) and escharotomy (OR: 2.66; 95% CI: 0.52-13.65; P-value: 0.24). For cases, mean age was 41 (SD: 13) years, mean total body surface area burned was 47% (SD: 18) and mean days in ICU until MDR specimen collection was 17 (SD: 10) days. Prior meropenem exposure, Gram-negative colonization on admission, escharotomy and superficial partial thickness burn size may be potentially important factors for increasing the risk of MDR Gram-negative infection in the critically ill burn patient. © 2017 Royal Australasian College of Surgeons.

Comparison between temperature distributions of an annular fuel rod of circular cross-section and of a hemoglobin shaped cross-section rod for PWR reactors in steady state conditions

International Nuclear Information System (INIS)

Oliveira, Maria Vitória A. de; Alvim, Antônio Carlos Marques

2017-01-01

The objective of this work is to make a comparison between the temperature distributions of an annular fuel rod of circular cross-section and a hemoglobin shaped cross-section for PWR reactors in steady state conditions. The motivation for this article is due to the fact that the symmetric form of the red globules particles allows the O 2 gases to penetrate the center of the cell homogeneously and quickly. The diffusion equation of gases in any environment is very similar to the heat diffusion equation: Diffusion - Fick's Law; Heat Flow - Fourier; where, the temperature (T) replaces the concentration (c). In previous works the comparison between the shape of solid fuel rods with circular section, and a with hemoglobin-shaped cross-section has proved that this new format optimizes the heat transfer, decreasing the thermal resistance between the center of the UO 2 pellets and the clad. With this, a significant increase in the specific power of the reactor was made possible (more precisely a 23% increase). Currently, the advantages of annular fuel rods are being studied and recent works have shown that 12 x 12 arrays of annular fuel rods perform better, increasing the specific power of the reactor by at least 20% in relation to solid fuel rods, without affecting the safety of the reactor. Our proposal is analyzing the temperature distribution in annular fuel rods with cross sections with red blood cell shape and compare with the theoretical results of the annular fuel rods of circular cross section, initially in steady state. (author)

Comparison between temperature distributions of an annular fuel rod of circular cross-section and of a hemoglobin shaped cross-section rod for PWR reactors in steady state conditions

Energy Technology Data Exchange (ETDEWEB)

Oliveira, Maria Vitória A. de; Alvim, Antônio Carlos Marques, E-mail: moliveira@con.ufrj.br, E-mail: alvim@nuclear.ufrj.br [Coordenacao de Pos-Graduacao e Pesquisa de Engenharia (COPPE/UFRJ), Rio de Janeiro, RJ (Brazil). Programa de Engenharia Nuclear

2017-07-01

The objective of this work is to make a comparison between the temperature distributions of an annular fuel rod of circular cross-section and a hemoglobin shaped cross-section for PWR reactors in steady state conditions. The motivation for this article is due to the fact that the symmetric form of the red globules particles allows the O{sub 2} gases to penetrate the center of the cell homogeneously and quickly. The diffusion equation of gases in any environment is very similar to the heat diffusion equation: Diffusion - Fick's Law; Heat Flow - Fourier; where, the temperature (T) replaces the concentration (c). In previous works the comparison between the shape of solid fuel rods with circular section, and a with hemoglobin-shaped cross-section has proved that this new format optimizes the heat transfer, decreasing the thermal resistance between the center of the UO{sub 2} pellets and the clad. With this, a significant increase in the specific power of the reactor was made possible (more precisely a 23% increase). Currently, the advantages of annular fuel rods are being studied and recent works have shown that 12 x 12 arrays of annular fuel rods perform better, increasing the specific power of the reactor by at least 20% in relation to solid fuel rods, without affecting the safety of the reactor. Our proposal is analyzing the temperature distribution in annular fuel rods with cross sections with red blood cell shape and compare with the theoretical results of the annular fuel rods of circular cross section, initially in steady state. (author)

Microbiological method for radiation sterilization (III). Development of identification software of spore-forming bacteria by using BBL CRYSTAL GP identification kit

International Nuclear Information System (INIS)

Hironiwa, Takayuki; Yamamoto, Yoko; Koshikawa, Tomihiko

2004-01-01

The part III in this title series describes the development of software for identification of spore-forming bacteria using the commercially available BBL CRYSTAL GP Identification Kit (Becton, Dickinson and Co., Ltd.), which is essentially for identification of Gram positive bacteria and is not always suitable for the spore-former in the radiation sterilization of medical devices. Isolation and identification of a spore-forming bacterium have to be confirmed by phase-contrast microscopy. The bacteria cultured overnight are to be inoculated in the Kit and cultured for 18-24 hr at 35-37 deg C with the lid attached by substrates for identification. Here, 30 substrates and probability of positive reactions to the substrates have been tested for spore-formers to make the computer software for final identification. The system is possible to identify 13 spp. of Bacillus, 4 of Paenibacillus, 2 of Brevibaccilus and 1 of Virgibacillus, which are the usual bioburden. For possible misidentification, re-isolation of the bacterium, prolonged culture, concentrated inoculation and re-consideration for ranking of identification the software provides are necessary as well as other identification approaches. Thus, as described in this series, the radio-resistance of, and radiation dose for, the bioburden can be evaluated more easily than hitherto, with use of the kits in radiation sterilization. (N.I.)

Chryseobacterium formosense sp. nov., isolated from the rhizosphere of Lactuca sativa L. (garden lettuce).

Science.gov (United States)

Young, Chiu-Chung; Kämpfer, Peter; Shen, Fo-Ting; Lai, Wei-An; Arun, A B

2005-01-01

A yellow-pigmented bacterial strain (CC-H3-2T), isolated from the rhizosphere of Lactuca sativa L. (garden lettuce) in Taiwan, was investigated using a polyphasic taxonomic approach. The cells were Gram-negative, rod-shaped and non-spore-forming. Phylogenetic analyses using the 16S rRNA gene sequence of the isolate indicated that the organism belongs to the genus Chryseobacterium, with the highest sequence similarity to the type strains of Chryseobacterium indoltheticum (97.7 %), Chryseobacterium scophthalmum (97.5 %), Chryseobacterium joostei (97.2 %) and Chryseobacterium defluvii (97.2 %). The major whole-cell fatty acids were iso-C(15 : 0) (52.2 %) and iso-C(17 : 0) 3-OH. DNA-DNA hybridization experiments revealed levels of only 27.4 % to C. scophthalmum, 27.1 % to C. indoltheticum, 14.1 % to C. joostei and 7.8 % to C. defluvii. DNA-DNA relatedness and biochemical and chemotaxonomic properties demonstrate that strain CC-H3-2T represents a novel species, for which the name Chryseobacterium formosense sp. nov. is proposed. The type strain is CC-H3-2T (=CCUG 49271T=CIP 108367T).

DNA/Ag Nanoparticles as Antibacterial Agents against Gram-Negative Bacteria

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Tomomi Takeshima

2015-03-01

Full Text Available Silver (Ag nanoparticles were produced using DNA extracted from salmon milt as templates. Particles spherical in shape with an average diameter smaller than 10 nm were obtained. The nanoparticles consisted of Ag as the core with an outermost thin layer of DNA. The DNA/Ag hybrid nanoparticles were immobilized over the surface of cotton based fabrics and their antibacterial efficiency was evaluated using E. coli as the typical Gram-negative bacteria. The antibacterial experiments were performed according to the Antibacterial Standard of Japanese Association for the Functional Evaluation of Textiles. The fabrics modified with DNA/Ag nanoparticles showed a high enough inhibitory and killing efficiency against E. coli at a concentration of Ag ≥ 10 ppm.

Bifidobacterium aquikefiri sp. nov., isolated from water kefir.

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Laureys, David; Cnockaert, Margo; De Vuyst, Luc; Vandamme, Peter

2016-03-01

A novel Bifidobacterium , strain LMG 28769 T , was isolated from a household water kefir fermentation process. Cells were Gram-stain-positive, non-motile, non-spore-forming, catalase-negative, oxidase-negative and facultatively anaerobic short rods. Analysis of its 16S rRNA gene sequence revealed Bifidobacterium crudilactis and Bifidobacterium psychraerophilum (97.4 and 97.1 % similarity towards the respective type strain sequences) as nearest phylogenetic neighbours. Its assignment to the genus Bifidobacterium was confirmed by the presence of fructose 6-phosphate phosphoketolase activity. Analysis of the hsp60 gene sequence revealed very low similarity with nucleotide sequences in the NCBI nucleotide database. The genotypic and phenotypic analyses allowed the differentiation of strain LMG 28769 T from all recognized Bifidobacterium species. Strain LMG 28769 T ( = CCUG 67145 T  = R 54638 T ) therefore represents a novel species, for which the name Bifidobacterium aquikefiri sp. nov. is proposed.

Combating multidrug-resistant Gram-negative bacterial infections.

Science.gov (United States)

Xu, Ze-Qi; Flavin, Michael T; Flavin, John

2014-02-01

Multidrug-resistant (MDR) bacterial infections, especially those caused by Gram-negative pathogens, have emerged as one of the world's greatest health threats. The development of novel antibiotics to treat MDR Gram-negative bacteria has, however, stagnated over the last half century. This review provides an overview of recent R&D activities in the search for novel antibiotics against MDR Gram-negatives. It provides emphasis in three key areas. First, the article looks at new analogs of existing antibiotic molecules such as β-lactams, tetracyclines, and aminoglycoside as well as agents against novel bacterial targets such as aminoacyl-tRNA synthetase and peptide deformylase. Second, it also examines alternative strategies to conventional approaches including cationic antimicrobial peptides, siderophores, efflux pump inhibitors, therapeutic antibodies, and renewed interest in abandoned treatments or those with limited indications. Third, the authors aim to provide an update on the current clinical development status for each drug candidate. The traditional analog approach is insufficient to meet the formidable challenge brought forth by MDR superbugs. With the disappointing results of the genomics approach for delivering novel targets and drug candidates, alternative strategies to permeate the bacterial cell membrane, enhance influx, disrupt efflux, and target specific pathogens via therapeutic antibodies are attractive and promising. Coupled with incentivized business models, governmental policies, and a clarified regulatory pathway, it is hoped that the antibiotic pipeline will be filled with an effective armamentarium to safeguard global health.

Volatile metabolites from some gram-negative bacteria

DEFF Research Database (Denmark)

Schöller, Charlotte; Molin, Søren; Wilkins, Ken

1997-01-01

A survey of volatile organic compounds (VOCs) excreted from various Gram-negative bacteria (Pseudomonas spp., Serratia spp. and Enterobacter spp.) was carried out. Compounds were identified by gas chromatography-mass spectrometry. VOCs identified included dimethyl disulphide, dimethyl trisulphide...

Complete Oxidation of Propionate, Valerate, Succinate, and Other Organic Compounds by Newly Isolated Types of Marine, Anaerobic, Mesophilic, Gram-Negative, Sulfur-Reducing Eubacteria

Science.gov (United States)

Finster, Kai; Bak, Friedhelm

1993-01-01

Anaerobic enrichment cultures with either propionate, succinate, lactate, or valerate and elemental sulfur and inocula from shallow marine or deep-sea sediments were dominated by rod-shaped motile bacteria after three transfers. By application of deep-agar dilutions, five eubacterial strains were obtained in pure culture and designated Kyprop, Gyprop, Kysw2, Gylac, and Kyval. All strains were gram negative and grew by complete oxidation of the electron donors and concomitant stoichiometric reduction of elemental sulfur to hydrogen sulfide. The isolates used acetate, propionate, succinate, lactate, pyruvate, oxaloacetate, maleate, glutamate, alanine, aspartate, and yeast extract. All isolates, except strain Gylac, used citrate as an electron donor but valerate was oxidized only by strain Kyval. Fumarate and malate were degraded by all strains without an additional electron donor or acceptor. Kyprop, Gyprop, and Gylac utilized elemental sulfur as the sole inorganic electron acceptor, while Kysw2 and Kyval also utilized nitrate, dimethyl sulfoxide, or Fe(III)-citrate as an electron acceptor. Images PMID:16348934

Gram negative wound infection in hospitalised adult burn patients--systematic review and metanalysis-.

Science.gov (United States)

Azzopardi, Ernest A; Azzopardi, Elayne; Camilleri, Liberato; Villapalos, Jorge; Boyce, Dean E; Dziewulski, Peter; Dickson, William A; Whitaker, Iain S

2014-01-01

Gram negative infection is a major determinant of morbidity and survival. Traditional teaching suggests that burn wound infections in different centres are caused by differing sets of causative organisms. This study established whether Gram-negative burn wound isolates associated to clinical wound infection differ between burn centres. Studies investigating adult hospitalised patients (2000-2010) were critically appraised and qualified to a levels of evidence hierarchy. The contribution of bacterial pathogen type, and burn centre to the variance in standardised incidence of Gram-negative burn wound infection was analysed using two-way analysis of variance. Pseudomonas aeruginosa, Klebsiella pneumoniae, Acinetobacter baumanni, Enterobacter spp., Proteus spp. and Escherichia coli emerged as the commonest Gram-negative burn wound pathogens. Individual pathogens' incidence did not differ significantly between burn centres (F (4, 20) = 1.1, p = 0.3797; r2 = 9.84). Gram-negative infections predominate in burn surgery. This study is the first to establish that burn wound infections do not differ significantly between burn centres. It is the first study to report the pathogens responsible for the majority of Gram-negative infections in these patients. Whilst burn wound infection is not exclusive to these bacteria, it is hoped that reporting the presence of this group of common Gram-negative "target organisms" facilitate clinical practice and target research towards a defined clinical demand.

Inverse design of an isotropic suspended Kirchhoff rod: theoretical and numerical results on the uniqueness of the natural shape

Science.gov (United States)

Bertails-Descoubes, Florence; Derouet-Jourdan, Alexandre; Romero, Victor; Lazarus, Arnaud

2018-04-01

Solving the equations for Kirchhoff elastic rods has been widely explored for decades in mathematics, physics and computer science, with significant applications in the modelling of thin flexible structures such as DNA, hair or climbing plants. As demonstrated in previous experimental and theoretical studies, the natural curvature plays an important role in the equilibrium shape of a Kirchhoff rod, even in the simple case where the rod is isotropic and suspended under gravity. In this paper, we investigate the reverse problem: can we characterize the natural curvature of a suspended isotropic rod, given an equilibrium curve? We prove that although there exists an infinite number of natural curvatures that are compatible with the prescribed equilibrium, they are all equivalent in the sense that they correspond to a unique natural shape for the rod. This natural shape can be computed efficiently by solving in sequence three linear initial value problems, starting from any framing of the input curve. We provide several numerical experiments to illustrate this uniqueness result, and finally discuss its potential impact on non-invasive parameter estimation and inverse design of thin elastic rods.

Incidence of carbapenem-resistant gram negatives in Italian transplant recipients: a nationwide surveillance study.

Science.gov (United States)

Lanini, Simone; Costa, Alessandro Nanni; Puro, Vincenzo; Procaccio, Francesco; Grossi, Paolo Antonio; Vespasiano, Francesca; Ricci, Andrea; Vesconi, Sergio; Ison, Michael G; Carmeli, Yehuda; Ippolito, Giuseppe

2015-01-01

Bacterial infections remain a challenge to solid organ transplantation. Due to the alarming spread of carbapenem-resistant gram negative bacteria, these organisms have been frequently recognized as cause of severe infections in solid organ transplant recipients. Between 15 May and 30 September 2012 we enrolled 887 solid organ transplant recipients in Italy with the aim to describe the epidemiology of gram negative bacteria spreading, to explore potential risk factors and to assess the effect of early isolation of gram negative bacteria on recipients' mortality during the first 90 days after transplantation. During the study period 185 clinical isolates of gram negative bacteria were reported, for an incidence of 2.39 per 1000 recipient-days. Positive cultures for gram negative bacteria occurred early after transplantation (median time 26 days; incidence rate 4.33, 1.67 and 1.14 per 1,000 recipient-days in the first, second and third month after SOT, respectively). Forty-nine of these clinical isolates were due to carbapenem-resistant gram negative bacteria (26.5%; incidence 0.63 per 1000 recipient-days). Carbapenems resistance was particularly frequent among Klebsiella spp. isolates (49.1%). Recipients with longer hospital stay and those who received either heart or lung graft were at the highest risk of testing positive for any gram negative bacteria. Moreover recipients with longer hospital stay, lung recipients and those admitted to hospital for more than 48h before transplantation had the highest probability to have culture(s) positive for carbapenem-resistant gram negative bacteria. Forty-four organ recipients died (0.57 per 1000 recipient-days) during the study period. Recipients with at least one positive culture for carbapenem-resistant gram negative bacteria had a 10.23-fold higher mortality rate than those who did not. The isolation of gram-negative bacteria is most frequent among recipient with hospital stays >48 hours prior to transplant and in those

Incidence of carbapenem-resistant gram negatives in Italian transplant recipients: a nationwide surveillance study.

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Simone Lanini

Full Text Available Bacterial infections remain a challenge to solid organ transplantation. Due to the alarming spread of carbapenem-resistant gram negative bacteria, these organisms have been frequently recognized as cause of severe infections in solid organ transplant recipients.Between 15 May and 30 September 2012 we enrolled 887 solid organ transplant recipients in Italy with the aim to describe the epidemiology of gram negative bacteria spreading, to explore potential risk factors and to assess the effect of early isolation of gram negative bacteria on recipients' mortality during the first 90 days after transplantation. During the study period 185 clinical isolates of gram negative bacteria were reported, for an incidence of 2.39 per 1000 recipient-days. Positive cultures for gram negative bacteria occurred early after transplantation (median time 26 days; incidence rate 4.33, 1.67 and 1.14 per 1,000 recipient-days in the first, second and third month after SOT, respectively. Forty-nine of these clinical isolates were due to carbapenem-resistant gram negative bacteria (26.5%; incidence 0.63 per 1000 recipient-days. Carbapenems resistance was particularly frequent among Klebsiella spp. isolates (49.1%. Recipients with longer hospital stay and those who received either heart or lung graft were at the highest risk of testing positive for any gram negative bacteria. Moreover recipients with longer hospital stay, lung recipients and those admitted to hospital for more than 48h before transplantation had the highest probability to have culture(s positive for carbapenem-resistant gram negative bacteria. Forty-four organ recipients died (0.57 per 1000 recipient-days during the study period. Recipients with at least one positive culture for carbapenem-resistant gram negative bacteria had a 10.23-fold higher mortality rate than those who did not.The isolation of gram-negative bacteria is most frequent among recipient with hospital stays >48 hours prior to transplant

Glycosaminoglycans are involved in pathogen adherence to corneal epithelial cells differently for Gram-positive and Gram-negative bacteria

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Beatriz García

2016-11-01

Full Text Available The epithelium of the cornea is continuously exposed to pathogens, and adhesion to epithelial cells is regarded as an essential first step in bacterial pathogenesis. In this article, the involvement of glycosaminoglycans in the adhesion of various pathogenic bacteria to corneal epithelial cells is analyzed. All microorganisms use glycosaminoglycans as receptors, but arranged in different patterns depending on the Gram-type of the bacterium. The heparan sulfate chains of syndecans are the main receptors, though other molecular species also seem to be involved, particularly in Gram-negative bacteria. Adherence is inhibited differentially by peptides, including heparin binding sequences, indicating the participation of various groups of Gram-positive and -negative adhesins. The length of the saccharides produces a major effect, and low molecular weight chains inhibit the binding of Gram-negative microorganisms but increase the adherence of Gram-positives. Pathogen adhesion appears to occur preferentially through sulfated domains, and is very dependent on N- and 6-O-sulfation of the glucosamine residue and, to a lesser extent, 2-O sulfation of uronic acid. These data show the differential use of corneal receptors, which could facilitate the development of new anti-infective strategies.

Flavobacterium nitratireducens sp. nov., an amylolytic bacterium of the family Flavobacteriaceae isolated from coastal surface seawater

Digital Repository Service at National Institute of Oceanography (India)

Nupur; Bhumika, V.; Srinivas, T.N.R.; AnilKumar, P.

A novel Gram-negative, rod-shaped, non-motile bacterium, designated strain N1 sup(T), was isolated from a marine water sample collected from the sea shore, Bay of Bengal, Visakhapatnam, India. The strain was positive for starch hydrolysis, nitrate...

Algoriphagus shivajiensis sp. nov., isolated from Cochin back water, India

Digital Repository Service at National Institute of Oceanography (India)

AnilKumar, P.; Bhumika, V.; Ritika, C; VijayaBhaskar, Y.; Priyashanth, P.; Aravind, R.; Bindu, E.; Srinivas, T.N.R.

Novel orange-pigmented, Gram-negative, rod-shaped, non-motile bacteria, designated strains NIO-S3 sup(T) and NIO-S4, were isolated from a water sample collected from Cochin back waters, Thanneermukkom and Arookutty, Kerala, India. Both strains were...

Vitellibacter nionensis sp. nov., isolated from shallow water hydrothermal vent of Espalamaca, Azores.

Digital Repository Service at National Institute of Oceanography (India)

Rajasabapathy, R.; Mohandass, C; Yoon, J; Dastager, S.G.; Liu, Q.; Khieu, T.-N.; Son, C; Li, W.-J; Colaco, A.

A novel, Gram-negative, non-motile, rod-shaped yellow pigmented bacterium, designated VBW088T was isolated from shallow water hydrothermal vent of Espalamaca, Azores. Phylogenetic analysis based on 16S rRNA gene sequences showed that strain VBW088...

Aliiglaciecola coringensis sp. nov., isolated from a water sample collected from mangrove forest in Coringa, Andhra Pradesh, India

Digital Repository Service at National Institute of Oceanography (India)

Gupta, V.; Sharma, G.; Srinivas, T.N.R.; AnilKumar, P.

A Gram-negative, rod shaped, motile, aerobic bacterium, designated as strain AK49(T) was isolated from a water sample from a mangrove forest in Coringa village, Andhra Pradesh, India. Strain AK49(T) was observed to form yellow coloured, smooth...

Methylopila capsulata gen. nov., sp. nov., a novel non-pigmented aerobic facultatively methylotrophic bacterium.

Science.gov (United States)

Doronina, N V; Trotsenko, Y A; Krausova, V I; Boulygina, E S; Tourova, T P

1998-10-01

A new genus, Methylopila, and one new species are described for a group of seven strains of facultatively methylotrophic bacteria with the serine pathway of C1 assimilation. These bacteria are aerobic, Gram-negative, non-spore--forming, motile, colourless rods that multiply by binary fission. Their DNA base content ranges from 66 to 70 mol % G + C. Their cellular fatty acid profile consists primarily of C18:1 omega 7 cis-vaccenic and C19:0 cyclopropane acids. The major hydroxy acid is 3-OH C14:0. The main ubiquinone is Q-10. The dominant cellular phospholipids are phosphatidylethanolamine and phosphatidylcholine. The new isolates have a low level of DNA-DNA homology (5-10%) with the type strains of the serine pathway methylobacteria belonging to the genera Methylobacterium, Aminobacter, Hyphomicrobium and Methylorhabdus. Another approach, involving 16S rRNA gene sequence analysis of strain IM1T, has shown that the new isolates represent a separate branch within the alpha-2 subclass of the Proteobacteria. The type species of the new genus is Methylopila capsulata sp. nov., with the type strain IM1T (= VKM B-1606T).

Longitudinally Vibrating Elastic Rods with Locally and Non-Locally Reacting Viscous Dampers

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Şefaatdin Yüksel

2005-01-01

Full Text Available Eigencharacteristics of a longitudinally vibrating elastic rod with locally and non-locally reacting damping are analyzed. The rod is considered as a continuous system and complex eigenfrequencies are determined as solution of a characteristic equation. The variation of the damping ratios with respect to damper locations and damping coefficients for the first four eigenfrequencies are obtained. It is shown that at any mode of locally or non-locally damped elastic rod, the variation of damping ratio with damper location is linearly proportional to absolute value of the mode shape of undamped system. It is seen that the increasing damping coefficient does not always increase the damping ratio and there are optimal values for the damping ratio. Optimal values for external damping coefficients of viscous dampers and locations of the dampers are presented.

Gram negative wound infection in hospitalised adult burn patients--systematic review and metanalysis-.

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Ernest A Azzopardi

Full Text Available BACKGROUND: Gram negative infection is a major determinant of morbidity and survival. Traditional teaching suggests that burn wound infections in different centres are caused by differing sets of causative organisms. This study established whether Gram-negative burn wound isolates associated to clinical wound infection differ between burn centres. METHODS: Studies investigating adult hospitalised patients (2000-2010 were critically appraised and qualified to a levels of evidence hierarchy. The contribution of bacterial pathogen type, and burn centre to the variance in standardised incidence of Gram-negative burn wound infection was analysed using two-way analysis of variance. PRIMARY FINDINGS: Pseudomonas aeruginosa, Klebsiella pneumoniae, Acinetobacter baumanni, Enterobacter spp., Proteus spp. and Escherichia coli emerged as the commonest Gram-negative burn wound pathogens. Individual pathogens' incidence did not differ significantly between burn centres (F (4, 20 = 1.1, p = 0.3797; r2 = 9.84. INTERPRETATION: Gram-negative infections predominate in burn surgery. This study is the first to establish that burn wound infections do not differ significantly between burn centres. It is the first study to report the pathogens responsible for the majority of Gram-negative infections in these patients. Whilst burn wound infection is not exclusive to these bacteria, it is hoped that reporting the presence of this group of common Gram-negative "target organisms" facilitate clinical practice and target research towards a defined clinical demand.

Bioengineered nisin A derivatives with enhanced activity against both Gram positive and Gram negative pathogens.

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Des Field

Full Text Available Nisin is a bacteriocin widely utilized in more than 50 countries as a safe and natural antibacterial food preservative. It is the most extensively studied bacteriocin, having undergone decades of bioengineering with a view to improving function and physicochemical properties. The discovery of novel nisin variants with enhanced activity against clinical and foodborne pathogens has recently been described. We screened a randomized bank of nisin A producers and identified a variant with a serine to glycine change at position 29 (S29G, with enhanced efficacy against S. aureus SA113. Using a site-saturation mutagenesis approach we generated three more derivatives (S29A, S29D and S29E with enhanced activity against a range of Gram positive drug resistant clinical, veterinary and food pathogens. In addition, a number of the nisin S29 derivatives displayed superior antimicrobial activity to nisin A when assessed against a range of Gram negative food-associated pathogens, including E. coli, Salmonella enterica serovar Typhimurium and Cronobacter sakazakii. This is the first report of derivatives of nisin, or indeed any lantibiotic, with enhanced antimicrobial activity against both Gram positive and Gram negative bacteria.

Bioengineered Nisin A Derivatives with Enhanced Activity against Both Gram Positive and Gram Negative Pathogens

Science.gov (United States)

Field, Des; Begley, Maire; O’Connor, Paula M.; Daly, Karen M.; Hugenholtz, Floor; Cotter, Paul D.; Hill, Colin; Ross, R. Paul

2012-01-01

Nisin is a bacteriocin widely utilized in more than 50 countries as a safe and natural antibacterial food preservative. It is the most extensively studied bacteriocin, having undergone decades of bioengineering with a view to improving function and physicochemical properties. The discovery of novel nisin variants with enhanced activity against clinical and foodborne pathogens has recently been described. We screened a randomized bank of nisin A producers and identified a variant with a serine to glycine change at position 29 (S29G), with enhanced efficacy against S. aureus SA113. Using a site-saturation mutagenesis approach we generated three more derivatives (S29A, S29D and S29E) with enhanced activity against a range of Gram positive drug resistant clinical, veterinary and food pathogens. In addition, a number of the nisin S29 derivatives displayed superior antimicrobial activity to nisin A when assessed against a range of Gram negative food-associated pathogens, including E. coli, Salmonella enterica serovar Typhimurium and Cronobacter sakazakii. This is the first report of derivatives of nisin, or indeed any lantibiotic, with enhanced antimicrobial activity against both Gram positive and Gram negative bacteria. PMID:23056510

[Antimicrobial therapy in severe infections with multidrug-resistant Gram-negative bacterias].

Science.gov (United States)

Duszyńska, Wiesława

2010-01-01

Multidrug-resistant Gram-negative bacteria pose a serious and rapidly emerging threat to patients in healthcare settings, and are especially prevalent and problematic in intensive therapy units. Recently, the emergence of pandrug-resistance in Gram-negative bacteria poses additional concerns. This review examines the clinical impact and epidemiology of multidrug-resistant Gram-negative bacteria as a cause of increased morbidity and mortality among ITU patients. Beta-lactamases, cephalosporinases and carbapenemases play the most important role in resistance to antibiotics. Despite the tendency to increased resistance, carbapenems administered by continuous infusion remain the most effective drugs in severe sepsis. Drug concentration monitoring, albeit rarely used in practice, is necessary to ensure an effective therapeutic effect.

The accuracy of Gram stain of respiratory specimens in excluding Staphylococcus aureus in ventilator-associated pneumonia.

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Gottesman, Tamar; Yossepowitch, Orit; Lerner, Evgenia; Schwartz-Harari, Orna; Soroksky, Arie; Yekutieli, Daniel; Dan, Michael

2014-10-01

To evaluate the Gram stain of deep tracheal aspirate as a tool to direct empiric antibiotic therapy, and more specifically as a tool to exclude the need for empiric antibiotic coverage against Staphylococcus aureus in ventilator-associated pneumonia (VAP). A prospective, single-center, observational, cohort study. All wards at a community hospital. Adult patients requiring mechanical ventilation, identified as having VAP in a 54-month prospective surveillance database. Sampling of lower airway secretions by deep endotracheal aspiration was taken from each patient who developed VAP. Samples were sent immediately for Gram stain and qualitative bacterial cultures. Demographic and relevant clinical data were collected; Gram stain, culture, and antibiotic susceptibility results were documented; and outcome was followed prospectively. The analysis included 114 consecutive patients with 115 episodes of VAP from June 2007 to January 2012. Sensitivity of Gram stain compared with culture was 90.47% for gram-positive cocci, 69.6% for gram-negative rods, and 50% for sterile cultures. Specificity was 82.5%, 77.8%, and 79%, respectively. Negative predictive value was high for gram-positive cocci (97%) and sterile cultures (96%) but low for gram-negative rods (20%). Acinetobacter baumanii (45%) and Pseudomonas aeruginosa (38 %) were the prevailing isolates. S aureus was found in 18.3% of the patients. Most isolates were multiresistant. Absence of gram-positive bacteria on Gram stain had a high negative predictive value. These data can be used to narrow the initial empiric antibiotic regimen and to avoid unnecessary exposure of patients to vancomycin and other antistaphyloccocal agents. Copyright © 2014 Elsevier Inc. All rights reserved.

In vitro susceptibility pattern of extended spectrum ?-lactamase producing gram negative bacilli against tetracyclines

International Nuclear Information System (INIS)

Gill, M.M.

2015-01-01

Extended Spectrum beta-lactamases (ESBLs) are emerging as common nosocomial pathogens and important cause of mortality and morbidity, if not treated properly. The need of the hour is to find effective treatment options for dealing with ESBL producing organisms. This study was aimed to evaluate in vitro susceptibility pattern of extended spectrum beta-lactamase producers against tetracyclines. Methods: This descriptive cross-sectional study was carried out in the department of Microbiology, Army Medical College, Rawalpindi, National University of Sciences and Technology over a period of 6 months. Seventy eight non-duplicate isolates were included in the study. ESBL detection was done using Jarlier et al method. In vitro susceptibility of tetracyclines like tetracycline, doxycycline, minocycline and tigecycline was then tested using Modified Kirby Bauer disc diffusion method. The zones of inhibition were measured after completion of incubation period and interpreted as per CLSI and FDA guidelines. Results: Approximately 56.4% of the isolates were Escherichia coli, 28.2% were Klebsiella pneumoniae, 10.26% were Enterobacter species, and 2.6% were each Klebsiella oxytoca and Acinetobacter species. ESBLs were found to be most sensitive to tigecycline, intermediate in susceptibility to minocycline while least sensitive to doxycycline and tetracycline. Conclusion: Among tetracyclines, tigecycline has best in vitro susceptibility against ESBL producing Gram negative rods. (author)

Complete Genome sequence of Burkholderia phymatum STM815, a broad host range and efficient nitrogen-fixing symbiont of Mimosa species

Energy Technology Data Exchange (ETDEWEB)

Moulin, Lionel [UMR, France; Klonowska, Agnieszka [UMR, France; Caroline, Bournaud [UMR, France; Booth, Kristina [University of Massachusetts; Vriezen, Jan A.C. [University of Massachusetts; Melkonian, Remy [UMR, France; James, Euan [James Hutton Institute, Dundee, United Kingdom; Young, Peter W. [University of York, United Kingdom; Bena, Gilles [UMR, France; Hauser, Loren John [ORNL; Land, Miriam L [ORNL; Kyrpides, Nikos C [U.S. Department of Energy, Joint Genome Institute; Bruce, David [Los Alamos National Laboratory (LANL); Chain, Patrick S. G. [Lawrence Livermore National Laboratory (LLNL); Copeland, A [U.S. Department of Energy, Joint Genome Institute; Pitluck, Sam [U.S. Department of Energy, Joint Genome Institute; Woyke, Tanja [U.S. Department of Energy, Joint Genome Institute; Lizotte-Waniewski, Michelle [University of Massachusetts; Bristow, James [U.S. Department of Energy, Joint Genome Institute; Riley, Monica [Woods Hole Oceanographic Institution (WHOI), Woods Hole

2014-01-01

Burkholderia phymatum is a soil bacterium able to develop a nitrogen-fixing symbiosis with species of the legume genus Mimosa, and is frequently found associated specifically with Mimosa pudica. The type strain of the species, STM 815T, was isolated from a root nodule in French Guiana in 2000. The strain is an aerobic, motile, non-spore forming, Gram-negative rod, and is a highly competitive strain for nodulation compared to other Mimosa symbionts, as it also nodulates a broad range of other legume genera and species. The 8,676,562 bp genome is composed of two chromosomes (3,479,187 and 2,697,374 bp), a megaplasmid (1,904,893 bp) and a plasmid hosting the symbiotic functions (595,108 bp).

Gram-positive and gram-negative bacteria induce different patterns of cytokine production in human mononuclear cells irrespective of taxonomic relatedness.

Science.gov (United States)

Skovbjerg, Susann; Martner, Anna; Hynsjö, Lars; Hessle, Christina; Olsen, Ingar; Dewhirst, Floyd E; Tham, Wilhelm; Wold, Agnes E

2010-01-01

Upon bacterial stimulation, tissue macrophages produce a variety of cytokines that orchestrate the immune response that clears the infection. We have shown that Gram-positives induce higher levels of interleukin-12 (IL-12), interferon-gamma (IFN-gamma), and tumor necrosis factor (TNF) from human peripheral blood mononuclear cells (PBMCs) than do Gram-negatives, which instead induce more of IL-6, IL-8, and IL-10. Here, we study whether these patterns follows or crosses taxonomic borders. PBMCs from blood donors were incubated with UV-inactivated bacteria representing 37 species from five phyla. IL-12, TNF, IL-1beta, IL-6, IL-8, and IL-10 were measured in the supernatants after 24 h and IFN-gamma after 5 days. Irrespective of phylogenetic position, Gram-positive bacteria induced much more IL-12 (nine times more on average) and IFN-gamma (seven times), more TNF (three times), and slightly more IL-1beta (1.5 times) than did Gram-negatives, which instead induced more IL-6 (1.5 times), IL-8 (1.9 times), and IL-10 (3.3 times) than did Gram-positives. A notable exception was the Gram-positive Listeria monocytogenes, which induced very little IL-12, IFN-gamma, and TNF. The results confirm the fundamental difference in innate immune responses to Gram-positive and Gram-negative bacteria, which crosses taxonomic borders and probably reflects differences in cell wall structure.

Pleural effusion adenosine deaminase: a candidate biomarker to discriminate between Gram-negative and Gram-positive bacterial infections of the pleural space

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Ruolin Li

2016-05-01

Full Text Available OBJECTIVES: Delay in the treatment of pleural infection may contribute to its high mortality. In this retrospective study, we aimed to evaluate the diagnostic accuracy of pleural adenosine deaminase in discrimination between Gram-negative and Gram-positive bacterial infections of the pleural space prior to selecting antibiotics. METHODS: A total of 76 patients were enrolled and grouped into subgroups according to Gram staining: 1 patients with Gram-negative bacterial infections, aged 53.2±18.6 years old, of whom 44.7% had empyemas and 2 patients with Gram-positive bacterial infections, aged 53.5±21.5 years old, of whom 63.1% had empyemas. The pleural effusion was sampled by thoracocentesis and then sent for adenosine deaminase testing, biochemical testing and microbiological culture. The Mann-Whitney U test was used to examine the differences in adenosine deaminase levels between the groups. Correlations between adenosine deaminase and specified variables were also quantified using Spearman’s correlation coefficient. Moreover, receiver operator characteristic analysis was performed to evaluate the diagnostic accuracy of pleural effusion adenosine deaminase. RESULTS: Mean pleural adenosine deaminase levels differed significantly between Gram-negative and Gram-positive bacterial infections of the pleural space (191.8±32.1 U/L vs 81.0±16.9 U/L, p<0.01. The area under the receiver operator characteristic curve was 0.689 (95% confidence interval: 0.570, 0.792, p<0.01 at the cutoff value of 86 U/L. Additionally, pleural adenosine deaminase had a sensitivity of 63.2% (46.0-78.2%; a specificity of 73.7% (56.9-86.6%; positive and negative likelihood ratios of 2.18 and 0.50, respectively; and positive and negative predictive values of 70.6% and 66.7%, respectively. CONCLUSIONS: Pleural effusion adenosine deaminase is a helpful alternative biomarker for early and quick discrimination of Gram-negative from Gram-positive bacterial infections of the

The structures of lipopolysaccharides from plant-associated gram-negative bacteria

DEFF Research Database (Denmark)

Molinaro, Antonio; Newman, Mari-Anne; Lanzetta, Rosa

2009-01-01

Gram-negative bacterial lipopolysaccharides (LPSs) have multiple roles in plant-microbe interactions. LPSs contribute to the low permeabilities of bacterial outer membranes, which act as barriers to protect bacteria from plant-derived antimicrobial substances. Conversely, perception of LPSs...... is an important prerequisite for any further understanding of the biological processes in plant-microbe interactions. Moreover, the LPSs from Gram-negative bacteria - especially those originating from plant-associated bacteria - are a great source of novel monosaccharides with unusual and occasionally astounding...

Comparison of in-house and commercial real time-PCR based carbapenemase gene detection methods in Enterobacteriaceae and non-fermenting gram-negative bacterial isolates.

Science.gov (United States)

Smiljanic, M; Kaase, M; Ahmad-Nejad, P; Ghebremedhin, B

2017-07-10

Carbapenemase-producing gram-negative bacteria are increasing globally and have been associated with outbreaks in hospital settings. Thus, the accurate detection of these bacteria in infections is mandatory for administering the adequate therapy and infection control measures. This study aimed to establish and evaluate a multiplex real-time PCR assay for the simultaneous detection of carbapenemase gene variants in gram-negative rods and to compare the performance with a commercial RT-PCR assay (Check-Direct CPE). 116 carbapenem-resistant Enterobacteriaceae, Pseudomonas aeruginosa and Acinetobacter baumannii isolates were genotyped for carbapenemase genes by PCR and sequencing. The defined isolates were used for the validation of the in-house RT-PCR by use of designed primer pairs and probes. Among the carbapenem-resistant isolates the genes bla KPC , bla VIM , bla NDM or bla OXA were detected. Both RT-PCR assays detected all bla KPC , bla VIM and bla NDM in the isolates. The in-house RT-PCR detected 53 of 67 (79.0%) whereas the commercial assay detected only 29 (43.3%) of the OXA genes. The in-house sufficiently distinguished the most prevalent OXA types (23-like and 48-like) in the melting curve analysis and direct detection of the genes from positive blood culture vials. The Check-Direct CPE and the in-house RT-PCR assay detected the carbapenem resistance from solid culture isolates. Moreover, the in-house assay enabled the identification of carbapenemase genes directly from positive blood-culture vials. However, we observed insufficient detection of various OXA genes in both assays. Nevertheless, the in-house RT-PCR detected the majority of the OXA type genes in Enterobacteriaceae and A. baumannii.

Different Use of Cell Surface Glycosaminoglycans As Adherence Receptors to Corneal Cells by Gram Positive and Gram Negative Pathogens

Science.gov (United States)

García, Beatriz; Merayo-Lloves, Jesús; Rodríguez, David; Alcalde, Ignacio; García-Suárez, Olivia; Alfonso, José F.; Baamonde, Begoña; Fernández-Vega, Andrés; Vazquez, Fernando; Quirós, Luis M.

2016-01-01

The epithelium of the cornea is continuously exposed to pathogens, and adhesion to epithelial cells is regarded as an essential first step in bacterial pathogenesis. In this article, the involvement of glycosaminoglycans in the adhesion of various pathogenic bacteria to corneal epithelial cells is analyzed. All microorganisms use glycosaminoglycans as receptors, but arranged in different patterns depending on the Gram-type of the bacterium. The heparan sulfate chains of syndecans are the main receptors, though other molecular species also seem to be involved, particularly in Gram-negative bacteria. Adherence is inhibited differentially by peptides, including heparin binding sequences, indicating the participation of various groups of Gram-positive, and -negative adhesins. The length of the saccharides produces a major effect, and low molecular weight chains inhibit the binding of Gram-negative microorganisms but increase the adherence of Gram-positives. Pathogen adhesion appears to occur preferentially through sulfated domains, and is very dependent on N- and 6-O-sulfation of the glucosamine residue and, to a lesser extent, 2-O sulfation of uronic acid. These data show the differential use of corneal receptors, which could facilitate the development of new anti-infective strategies. PMID:27965938

Rod-shaped silica particles derivatized with elongated silver nanoparticles immobilized within mesopores

Energy Technology Data Exchange (ETDEWEB)

Mnasri, Najib [Institut Charles Gerhardt de Montpellier, CNRS UMR 5253, Université Montpellier, Place Eugène Bataillon, 34095 Montpellier Cedex 5 (France); Materials, Environment and Energy Laboratory (UR14ES26), Faculty of Science, University of Gafsa, 2112 Gafsa (Tunisia); Charnay, Clarence; Ménorval, Louis-Charles de [Institut Charles Gerhardt de Montpellier, CNRS UMR 5253, Université Montpellier, Place Eugène Bataillon, 34095 Montpellier Cedex 5 (France); Elaloui, Elimame [Materials, Environment and Energy Laboratory (UR14ES26), Faculty of Science, University of Gafsa, 2112 Gafsa (Tunisia); Zajac, Jerzy, E-mail: jerzy.zajac@umontpellier.fr [Institut Charles Gerhardt de Montpellier, CNRS UMR 5253, Université Montpellier, Place Eugène Bataillon, 34095 Montpellier Cedex 5 (France)

2016-11-15

Silver-derivatized silica particles possessing a non-spherical morphology and surface plasmon resonance properties have been achieved. Nanometer-sized silica rods with uniformly sized mesopore channels were prepared first making use of alkyltrimethyl ammonium surfactants as porogens and the 1:0.10 tetraethyl orthosilicate (TEOS) : 3-aminopropyltriethoxysilane (APTES) mixture as a silicon source. Silica rods were subsequently functionalized by introducing elongated silver nanoparticles within the intra-particle mesopores thanks to the AgNO{sub 3} reduction procedure based on the action of hemiaminal groups previously located on the mesopore walls. The textural and structural features of the samples were inferred from the combined characterization studies including SEM and TEM microscopy, nitrogen adsorption-desorption at 77 K, powder XRD in the small- and wide-angle region, as well as UV–visible spectroscopy. {sup 129}Xe NMR spectroscopy appeared particularly useful to obtain a correct information about the porous structure of rod-shaped silica particles and the silver incorporation within their intra-particle mesopores. - Highlights: • Mesoporous monodisperse submicron-sized silica rods were achieved. • Silver nanoparticles were located lengthwise within the intra-particle mesopores. • Textural and plasmonic properties of particles studied by {sup 129}Xe NMR and UV–Vis.

The reaction mechanism for dehydration process catalyzed by type I dehydroquinate dehydratase from Gram-negative Salmonella enterica

Science.gov (United States)

Yao, Yuan; Li, Ze-Sheng

2012-01-01

The fundamental reaction mechanism for the dehydration process catalyzed by type I dehydroquinate dehydratase from Gram-negative Salmonella enterica has been studied by density functional theory calculations. The results indicate that the dehydration process undergoes a two-step cis-elimination mechanism, which is different from the previously proposed one. The catalytic roles of both the highly conserved residue His143 and the Schiff base formed between the substrate and Lys170 have also been elucidated. The structural and mechanistic insight presented here may direct the design of type I dehydroquinate dehydratase enzyme inhibitors as non-toxic antimicrobials, anti-fungals, and herbicides.

Rationalizing the permeation of polar antibiotics into Gram-negative bacteria

International Nuclear Information System (INIS)

Scorciapino, Mariano Andrea; Acosta-Gutierrez, Silvia; Benkerrou, Dehbia; D’Agostino, Tommaso; Malloci, Giuliano; Samanta, Susruta; Bodrenko, Igor; Ceccarelli, Matteo

2017-01-01

The increasing level of antibiotic resistance in Gram-negative bacteria, together with the lack of new potential drug scaffolds in the pipeline, make the problem of infectious diseases a global challenge for modern medicine. The main reason that Gram-negative bacteria are particularly challenging is the presence of an outer cell-protecting membrane, which is not present in Gram-positive species. Such an asymmetric bilayer is a highly effective barrier for polar molecules. Several protein systems are expressed in the outer membrane to control the internal concentration of both nutrients and noxious species, in particular: (i) water-filled channels that modulate the permeation of polar molecules and ions according to concentration gradients, and (ii) efflux pumps to actively expel toxic compounds. Thus, besides expressing specific enzymes for drugs degradation, Gram-negative bacteria can also resist by modulating the influx and efflux of antibiotics, keeping the internal concentration low. However, there are no direct and robust experimental methods capable of measuring the permeability of small molecules, thus severely limiting our knowledge of the molecular mechanisms that ultimately control the permeation of antibiotics through the outer membrane. This is the innovation gap to be filled for Gram-negative bacteria. This review is focused on the permeation of small molecules through porins, considered the main path for the entry of polar antibiotics into Gram-negative bacteria. A fundamental understanding of how these proteins are able to filter small molecules is a prerequisite to design/optimize antibacterials with improved permeation. The level of sophistication of modern molecular modeling algorithms and the advances in new computer hardware has made the simulation of such complex processes possible at the molecular level. In this work we aim to share our experience and perspectives in the context of a multidisciplinary extended collaboration within the IMI

Rationalizing the permeation of polar antibiotics into Gram-negative bacteria

Science.gov (United States)

Scorciapino, Mariano Andrea; Acosta-Gutierrez, Silvia; Benkerrou, Dehbia; D'Agostino, Tommaso; Malloci, Giuliano; Samanta, Susruta; Bodrenko, Igor; Ceccarelli, Matteo

2017-03-01

The increasing level of antibiotic resistance in Gram-negative bacteria, together with the lack of new potential drug scaffolds in the pipeline, make the problem of infectious diseases a global challenge for modern medicine. The main reason that Gram-negative bacteria are particularly challenging is the presence of an outer cell-protecting membrane, which is not present in Gram-positive species. Such an asymmetric bilayer is a highly effective barrier for polar molecules. Several protein systems are expressed in the outer membrane to control the internal concentration of both nutrients and noxious species, in particular: (i) water-filled channels that modulate the permeation of polar molecules and ions according to concentration gradients, and (ii) efflux pumps to actively expel toxic compounds. Thus, besides expressing specific enzymes for drugs degradation, Gram-negative bacteria can also resist by modulating the influx and efflux of antibiotics, keeping the internal concentration low. However, there are no direct and robust experimental methods capable of measuring the permeability of small molecules, thus severely limiting our knowledge of the molecular mechanisms that ultimately control the permeation of antibiotics through the outer membrane. This is the innovation gap to be filled for Gram-negative bacteria. This review is focused on the permeation of small molecules through porins, considered the main path for the entry of polar antibiotics into Gram-negative bacteria. A fundamental understanding of how these proteins are able to filter small molecules is a prerequisite to design/optimize antibacterials with improved permeation. The level of sophistication of modern molecular modeling algorithms and the advances in new computer hardware has made the simulation of such complex processes possible at the molecular level. In this work we aim to share our experience and perspectives in the context of a multidisciplinary extended collaboration within the IMI

Reactor core with rod-shaped fuel cells

International Nuclear Information System (INIS)

Dworak, A.

1975-01-01

Power distribution in a high-temperature gas-cooled reactor is optimized. Especially the axial as well as the radial power distribution is kept constant, the core consisting of several consecutive rod-shaped fuel cells. To this end, the dwell times of the fuel cells are fitted to the given power distribution. Fuel cells with equal dwell times, seen in flow direction, are arranged side by side, and those with the shortest dwell times are placed in areas with the greatest power release. These areas ly on the coolant inlet side. To keep the power distribution constant, fuel cells with neutron poison or absorber rods with absorbing rates decreasing in flow direction can also be inserted. (RW/PB) [de

Neither Single nor a Combination of Routine Laboratory Parameters can Discriminate between Gram-positive and Gram-negative Bacteremia

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Ratzinger, Franz; Dedeyan, Michel; Rammerstorfer, Matthias; Perkmann, Thomas; Burgmann, Heinz; Makristathis, Athanasios; Dorffner, Georg; Loetsch, Felix; Blacky, Alexander; Ramharter, Michael

2015-01-01

Adequate early empiric antibiotic therapy is pivotal for the outcome of patients with bloodstream infections. In clinical practice the use of surrogate laboratory parameters is frequently proposed to predict underlying bacterial pathogens; however there is no clear evidence for this assumption. In this study, we investigated the discriminatory capacity of predictive models consisting of routinely available laboratory parameters to predict the presence of Gram-positive or Gram-negative bacteremia. Major machine learning algorithms were screened for their capacity to maximize the area under the receiver operating characteristic curve (ROC-AUC) for discriminating between Gram-positive and Gram-negative cases. Data from 23,765 patients with clinically suspected bacteremia were screened and 1,180 bacteremic patients were included in the study. A relative predominance of Gram-negative bacteremia (54.0%), which was more pronounced in females (59.1%), was observed. The final model achieved 0.675 ROC-AUC resulting in 44.57% sensitivity and 79.75% specificity. Various parameters presented a significant difference between both genders. In gender-specific models, the discriminatory potency was slightly improved. The results of this study do not support the use of surrogate laboratory parameters for predicting classes of causative pathogens. In this patient cohort, gender-specific differences in various laboratory parameters were observed, indicating differences in the host response between genders. PMID:26522966

Nanoparticle targeting of Gram-positive and Gram-negative bacteria for magnetic-based separations of bacterial pathogens

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Lu, Hoang D.; Yang, Shirley S.; Wilson, Brian K.; McManus, Simon A.; Chen, Christopher V. H.-H.; Prud'homme, Robert K.

2017-04-01

Antimicrobial resistance is a healthcare problem of increasing significance, and there is increasing interest in developing new tools to address bacterial infections. Bacteria-targeting nanoparticles hold promise to improve drug efficacy, compliance, and safety. In addition, nanoparticles can also be used for novel applications, such as bacterial imaging or bioseperations. We here present the use of a scalable block-copolymer-directed self-assembly process, Flash NanoPrecipitation, to form zinc(II)-bis(dipicolylamine) modified nanoparticles that bind to both Gram-positive and Gram-negative bacteria with specificity. Particles have tunable surface ligand densities that change particle avidity and binding efficacy. A variety of materials can be encapsulated into the core of the particles, such as optical dyes or iron oxide colloids, to produce imageable and magnetically active bacterial targeting constructs. As a proof-of-concept, these particles are used to bind and separate bacteria from solution in a magnetic column. Magnetic manipulation and separation would translate to a platform for pathogen identification or removal. These magnetic and targeted nanoparticles enable new methods to address bacterial infections.

Efforts to identify spore forming bacillus

Energy Technology Data Exchange (ETDEWEB)

Zuleiha, M.S.; Hilmy, N. (National Atomic Energy Agency, Jakarta (Indonesia). Pasar Djumat Research Centre)

1982-04-01

Efforts to identify 47 species of radioresistant spore forming bacillus sp. isolated from locally produced medical devices have been carried out. The identifications was conducted using 19 kinds of biochemical tests and compared to species to bacillus subtilis W. T.; bacillus pumilus E 601 and bacillus sphaericus Csub(I)A. The results showed that bacillus sp. examined could be divided into 6 groups, i.e. bacillus cereus; bacillus subtilis; bacillus stearothermophylus; bacillus coagulans; bacillus sphaericus and bacillus circulans.

Efforts to identify spore forming bacillus

International Nuclear Information System (INIS)

Zuleiha, M.S.; Hilmy, Nazly

1982-01-01

Efforts to identify 47 species of radioresistant spore forming bacillus sp. isolated from locally produced medical devices have been carried out. The identifications was conducted using 19 kinds of biochemical tests and compared to species to bacillus subtilis W. T.; bacillus pumilus E 601 and bacillus sphaericus Csub(I)A. The results showed that bacillus sp. examined could be divided into 6 groups, i.e. bacillus cereus; bacillus subtilis; bacillus stearothermophylus; bacillus coagulans; bacillus sphaericus and bacillus circulans. (author)

Antimicrobial activity of metal oxide nanoparticles against Gram-positive and Gram-negative bacteria: a comparative study

Directory of Open Access Journals (Sweden)

Azam A

2012-12-01

Full Text Available Ameer Azam,1,2 Arham S Ahmed,2 Mohammad Oves,3 Mohammad S Khan,3 Sami S Habib,1 Adnan Memic11Centre of Nanotechnology, King Abdulaziz University, Jeddah, Saudi Arabia; 2Centre of Excellence in Materials Science (Nanomaterials, 3Department of Agricultural Microbiology, Aligarh Muslim University, Aligarh, IndiaBackground: Nanomaterials have unique properties compared to their bulk counterparts. For this reason, nanotechnology has attracted a great deal of attention from the scientific community. Metal oxide nanomaterials like ZnO and CuO have been used industrially for several purposes, including cosmetics, paints, plastics, and textiles. A common feature that these nanoparticles exhibit is their antimicrobial behavior against pathogenic bacteria. In this report, we demonstrate the antimicrobial activity of ZnO, CuO, and Fe2O3 nanoparticles against Gram-positive and Gram-negative bacteria.Methods and results: Nanosized particles of three metal oxides (ZnO, CuO, and Fe2O3 were synthesized by a sol–gel combustion route and characterized by X-ray diffraction, Fourier-transform infrared spectroscopy, and transmission electron microscopy techniques. X-ray diffraction results confirmed the single-phase formation of all three nanomaterials. The particle sizes were observed to be 18, 22, and 28 nm for ZnO, CuO, and Fe2O3, respectively. We used these nanomaterials to evaluate their antibacterial activity against both Gram-negative (Escherichia coli and Pseudomonas aeruginosa and Gram-positive (Staphylococcus aureus and Bacillus subtilis bacteria.Conclusion: Among the three metal oxide nanomaterials, ZnO showed greatest antimicrobial activity against both Gram-positive and Gram-negative bacteria used in this study. It was observed that ZnO nanoparticles have excellent bactericidal potential, while Fe2O3 nanoparticles exhibited the least bactericidal activity. The order of antibacterial activity was demonstrated to be the following: ZnO > CuO > Fe2O3

In vitro susceptibility of gram-negative bacterial isolates to chlorhexidine gluconate.

Science.gov (United States)

Mengistu, Y; Erge, W; Bellete, B

1999-05-01

To investigate the susceptibility of clinical isolates of gram-negative bacteria to chlorhexidine gluconate. Prospective laboratory study. Tikur Anbessa Hospital, Addis Ababa, Ethiopia. Clinical specimens from 443 hospital patients. Significant number of gram negative bacteria were not inhibited by chlorhexidine gluconate (0.02-0.05%) used for antisepsis. Four hundred and forty three strains of gram-negative bacteria were isolated from Tikur Anbessa Hospital patients. Escherichia coli (31.6%) and Klebsiella pneumoniae (23%) were the most frequently isolated bacteria followed by Proteus species (13.3%), Pseudomonas species (9.2%), and Citrobacter species (6.1%). Each organism was tested to chlorhexidine gluconate (CHG), minimum inhibitory concentration (MIC) ranging from 0.0001% to 1%w/v. All Salmonella species and E. coli were inhibited by CHG, MIC or = 0.1%). Our results showed that a significant number of the gram-negative bacterial isolates were not inhibited by CHG at the concentration used for disinfection of wounds or instruments (MIC 0.02-0.05% w/v). It is therefore important to select appropriate concentration of this disinfectant and rationally use it for disinfection and hospital hygiene. Continuing follow up and surveillance is also needed to detect resistant bacteria to chlorhexidine or other disinfectants in time.

Resistance to oral antibiotics in 4569 Gram-negative rods isolated from urinary tract infection in children.

Science.gov (United States)

Calzi, Anna; Grignolo, Sara; Caviglia, Ilaria; Calevo, Maria Grazia; Losurdo, Giuseppe; Piaggio, Giorgio; Bandettini, Roberto; Castagnola, Elio

2016-09-01

To investigate antibiotic resistance among pathogens isolated from urines in a tertiary care children's hospital in Italy. Retrospective analysis of prospectively collected data on antibiotic susceptibility of Gram-negatives isolated from urines at the Istituto Giannina Gaslini, Genoa - Italy from 2007 to 2014. Antibiotic susceptibility was evaluated. By means of CLSI criteria from 2007 to 2010, while from 2011 EUCAST criteria were adopted. Data on susceptibility to amoxicillin-clavulanate, co-trimoxazole, cefuroxime, nitrofurantoin, fosfomycin and ciprofloxacin were evaluated for Escherichia coli, while for other Enterobacteriaceae data were collected for amoxicillin-clavulanate, co-trimoxazole and ciprofloxacin and for ciprofloxacin against Pseudomonas aeruginosa. Univariate and multivariable analyses were performed for risk factors associated with resistance. A total of 4596 Gram-negative strains were observed in 3364 patients. A significant increase in the proportion of resistant strains was observed for E.coli against amoxicillin-clavulanate, cefuroxime and ciprofloxacin and for others Enterobacteriaceae against co-trimoxazole and ciprofloxacin. Resistance to nitrofurantoin and fosfomycin was very infrequent in E.coli. Logistic regression analysis showed that repeated episode of urinary tract infections was a risk factor for E.coli resistance to amoxicillin-clavulanate, co-trimoxazole and cefuroxime, while admission in one of the Units usually managing children with urinary tract malformations was significantly associated to resistance to amoxicillin-clavulanate and cefuroxime. In conclusion the present study shows an increase in antibiotic resistance in pediatric bacteria isolated from urines in children, especially in presence of repeated episodes and/or urinary tract malformations. This resistance is worrisome for beta-lactams and cotrimoxazole, and start to increase also for fluoroquinolones while nitrofurantoin and fosfomycin still could represent useful

The Exosporium of B.cereus Contains a Binding Site for gC1qR/p33: Implication in Spore Attachment and/or Entry.

Energy Technology Data Exchange (ETDEWEB)

GHEBREHIWET,B.; TANTRAL, L.; TITMUS, M.A.; PANESSA-WARREN, B.J.; TORTORA, G.T.; WONG, S.S.; WARREN, J.B.

2008-01-01

B. cereus, is a member of a genus of aerobic, gram-positive, spore-forming rod-like bacilli, which includes the deadly, B. anthracis. Preliminary experiments have shown that gC1qR binds to B.cereus spores that have been attached to microtiter plates. The present studies were therefore undertaken, to examine if cell surface gC1qR plays a role in B.cereus spore attachment and/or entry. Monolayers of human colon carcinoma (Caco-2) and lung cells were grown to confluency on 6 mm coverslips in shell vials with gentle swirling in a shaker incubator. Then, 2 {micro}l of a suspension of strain SB460 B.cereus spores (3x10{sup 8}/ml, in sterile water), were added and incubated (1-4 h; 36{sup 0} C) in the presence or absence of anti-gC1qR mAb-carbon nanoloops. Examination of these cells by EM revealed that: (1) When B. cereus endospores contacted the apical Caco-2 cell surface, or lung cells, gClqR was simultaneously detectable, indicating upregulation of the molecule. (2) In areas showing spore contact with the cell surface, gClqR expression was often adjacent to the spores in association with microvilli (Caco-2 cells) or cytoskeletal projections (lung cells). (3) Furthermore, the exosporia of the activated and germinating spores were often decorated with mAb-nanoloops. These observations were further corroborated by experiments in which B.cereus spores were readily taken up by monocytes and neutrophils, and this uptake was partially inhibited by mAb 60.11, which recognizes the C1q binding site on gC1qR. Taken together, the data suggest a role, for gC1qR at least in the initial stages of spore attachment and/or entry.

Non-contiguous finished genome sequence and description of Streptococcus varani sp. nov.

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S. Bakour

2016-05-01

Full Text Available Strain FF10T (= CSUR P1489 = DSM 100884 was isolated from the oral cavity of a lizard (Varanus niloticus in Dakar, Senegal. Here we used a polyphasic study including phenotypic and genomic analyses to describe the strain FF10T. Results support strain FF10T being a Gram-positive coccus, facultative anaerobic bacterium, catalase-negative, non-motile and non-spore forming. The sequenced genome counts 2.46 Mb with one chromosome but no plasmid. It exhibits a G+C content of 40.4% and contains 2471 protein-coding and 45 RNA genes. On the basis of these data, we propose the creation of Streptococcus varani sp. nov.

Mechanistic antimicrobial approach of extracellularly synthesized silver nanoparticles against gram positive and gram negative bacteria

Energy Technology Data Exchange (ETDEWEB)

Tamboli, Dhawal P.; Lee, Dae Sung, E-mail: daesung@knu.ac.kr

2013-09-15

Highlights: • Bacterial extracelluar enzymes stabilized the silver nanoparticles (AgNPs). • AgNPs formation was characterized by analytical techniques such as UV–vis, TEM, and FTIR. • AgNPs showed obvious antimicrobial activity against both gram positive and gram negative microorganisms. • A mechanism of AgNPs’ antimicrobial activity was proposed. -- Abstract: The development of eco-friendly and reliable processes for the synthesis of nanoparticles has attracted considerable interest in nanotechnology. In this study, an extracellular enzyme system of a newly isolated microorganism, Exiguobacterium sp. KNU1, was used for the reduction of AgNO{sub 3} solutions to silver nanoparticles (AgNPs). The extracellularly biosynthesized AgNPs were characterized by UV–vis spectroscopy, Fourier transform infra-red spectroscopy and transmission electron microscopy. The AgNPs were approximately 30 nm (range 5–50 nm) in size, well-dispersed and spherical. The AgNPs were evaluated for their antimicrobial effects on different gram negative and gram positive bacteria using the minimum inhibitory concentration method. Reasonable antimicrobial activity against Salmonella typhimurium, Pseudomonas aeruginosa, Escherichia coli and Staphylococcus aureus was observed. The morphological changes occurred in all the microorganisms tested. In particular, E. coli exhibited DNA fragmentation after being treated with the AgNPs. Finally, the mechanism for their bactericidal activity was proposed according to the results of scanning electron microscopy and single cell gel electrophoresis.

Mechanistic antimicrobial approach of extracellularly synthesized silver nanoparticles against gram positive and gram negative bacteria

International Nuclear Information System (INIS)

Tamboli, Dhawal P.; Lee, Dae Sung

2013-01-01

Highlights: • Bacterial extracelluar enzymes stabilized the silver nanoparticles (AgNPs). • AgNPs formation was characterized by analytical techniques such as UV–vis, TEM, and FTIR. • AgNPs showed obvious antimicrobial activity against both gram positive and gram negative microorganisms. • A mechanism of AgNPs’ antimicrobial activity was proposed. -- Abstract: The development of eco-friendly and reliable processes for the synthesis of nanoparticles has attracted considerable interest in nanotechnology. In this study, an extracellular enzyme system of a newly isolated microorganism, Exiguobacterium sp. KNU1, was used for the reduction of AgNO 3 solutions to silver nanoparticles (AgNPs). The extracellularly biosynthesized AgNPs were characterized by UV–vis spectroscopy, Fourier transform infra-red spectroscopy and transmission electron microscopy. The AgNPs were approximately 30 nm (range 5–50 nm) in size, well-dispersed and spherical. The AgNPs were evaluated for their antimicrobial effects on different gram negative and gram positive bacteria using the minimum inhibitory concentration method. Reasonable antimicrobial activity against Salmonella typhimurium, Pseudomonas aeruginosa, Escherichia coli and Staphylococcus aureus was observed. The morphological changes occurred in all the microorganisms tested. In particular, E. coli exhibited DNA fragmentation after being treated with the AgNPs. Finally, the mechanism for their bactericidal activity was proposed according to the results of scanning electron microscopy and single cell gel electrophoresis

Expanding the potential of NAI-107 for treating serious ESKAPE pathogens: synergistic combinations against Gram-negatives and bactericidal activity against non-dividing cells.

Science.gov (United States)

Brunati, Cristina; Thomsen, Thomas T; Gaspari, Eleonora; Maffioli, Sonia; Sosio, Margherita; Jabes, Daniela; Løbner-Olesen, Anders; Donadio, Stefano

2018-02-01

To characterize NAI-107 and related lantibiotics for their in vitro activity against Gram-negative pathogens, alone or in combination with polymyxin, and against non-dividing cells or biofilms of Staphylococcus aureus. NAI-107 was also evaluated for its propensity to select or induce self-resistance in Gram-positive bacteria. We used MIC determinations and chequerboard experiments to establish the antibacterial activity of the examined compounds against target microorganisms. Time-kill assays were used to evaluate killing of exponential and stationary-phase cells. The effects on biofilms (growth inhibition and biofilm eradication) were evaluated using biofilm-coated pegs. The frequency of spontaneous resistant mutants was evaluated by either direct plating or by continuous sub-culturing at 0.5 × MIC levels, followed by population analysis profiles. The results showed that NAI-107 and its brominated variant are highly active against Neisseria gonorrhoeae and some other fastidious Gram-negative pathogens. Furthermore, all compounds strongly synergized with polymyxin against Acinetobacter baumannii, Escherichia coli, Klebsiella pneumoniae and Pseudomonas aeruginosa, and showed bactericidal activity. Surprisingly, NAI-107 alone was bactericidal against non-dividing A. baumannii cells. Against S. aureus, NAI-107 and related lantibiotics showed strong bactericidal activity against dividing and non-dividing cells. Activity was also observed against S. aureus biofilms. As expected for a lipid II binder, no significant resistance to NAI-107 was observed by direct plating or serial passages. Overall, the results of the current work, along with previously published results on the efficacy of NAI-107 in experimental models of infection, indicate that this lantibiotic represents a promising option in addressing the serious threat of antibiotic resistance. © The Author 2017. Published by Oxford University Press on behalf of the British Society for Antimicrobial

Karakterisasi ekstrak kasar fitase termofilik dari bakteri kawah Ijen Banyuwangi, isolat AP-17

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Aline Puspita Kusumadjaja

2010-12-01

Full Text Available Crude thermophilic phytase was produced by isolate AP-17 that has been isolated from Ijen Crater Banyuwangi. Based on Gram test, isolate AP-17 was gram positive spore forming rod shape bacteria so that it was identified as Bacillus sp. AP-17. Crude thermophilic phytase isolated from Bacillus sp. AP-17 had the optimum temperature at 75 ° C with activity of 0.1413 U/ml, and its optimum pH was at pH 6 with activity of 0.0875 U/ml. The enzyme was stable when heated at 75 ° C for three hours and still had 90% activity when it was exposed at pH 5 €“8, optimum temperature, for one hour.

PHYLOGENETIC ANALYSIS AND AUTECOLOGY OF SPORE-FORMING BACTERIA FROM HYPERSALINE ENVIRONMENTS.

Science.gov (United States)

Gladka, G V; Romanovskaya, V A; Tashyreva, H O; Tashyrev, O B

2015-01-01

Multi-resistant to extreme factors spore-forming bacteria of Bacillus genus are isolated from hypersaline environments of the Crimea (Ukraine) and the Dead Sea (Israel). Phylogenetic analysis showed distinction of dominating extremophilic culturable species in studied regions. In Crimean environments they are B. mojavensis and B. simplex, in the Dead Sea ecosystem--B. subtilis subsp. spizizenii, B. subtilis subsp. subtilis, B. licheniformis and B. simplex. Isolates are simultaneously halotolerant and resistant to UV radiation. Strains isolated from the Dead Sea and the Crimea environments were resistant to UV: LD90 and LD99.99 made 100-170 J/m2 and 750-1500 J/m2 respectively. Spores showed higher UV-resistance (LD99.99-2500 J/m2) than the vegetative cells. However the number of spores made 0.02-0.007% of the whole cell population, and should not significantly affect the UV LD99.99 value. Isolates of both environments were halotolerant in the range of 0.1-10% NaCl and thermotolerant in the range of 20-50 °C, and didn't grow at 15 °C. Survival strategy of spore-forming bacteria from hypersaline environments under high UV radiation level can be performed by spore formation which minimize cell damage as well as efficient DNA-repair systems that remove damages.

Rubeoparvulum massiliense gen. nov., sp. nov., a new bacterial genus isolated from the human gut of a Senegalese infant with severe acute malnutrition

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M. Tidjani Alou

2017-01-01

Full Text Available Rubeoparvulum massiliense strain mt6T was isolated from the gut microbiota of a severely malnourished boy from Senegal and consisted of facultative anaerobic, spore-forming, nonmotile and Gram-negative rods. R. massiliense showed a 92% similarity with the 16S rRNA of Bacillus mannanilyticus. The genome of strain mt6T is 2 843 796 bp long with a 43.75% G+C content. It contains 2735 protein-coding genes and 76 RNA genes, among which are nine rRNA genes.

The target of daptomycin is absent from Escherichia coli and other gram-negative pathogens.

Science.gov (United States)

Randall, Christopher P; Mariner, Katherine R; Chopra, Ian; O'Neill, Alex J

2013-01-01

Antistaphylococcal agents commonly lack activity against Gram-negative bacteria like Escherichia coli owing to the permeability barrier presented by the outer membrane and/or the action of efflux transporters. When these intrinsic resistance mechanisms are artificially compromised, such agents almost invariably demonstrate antibacterial activity against Gram negatives. Here we show that this is not the case for the antibiotic daptomycin, whose target appears to be absent from E. coli and other Gram-negative pathogens.

Contamination pathways of spore-forming bacteria in a vegetable cannery.

Science.gov (United States)

Durand, Loïc; Planchon, Stella; Guinebretiere, Marie-Hélène; André, Stéphane; Carlin, Frédéric; Remize, Fabienne

2015-06-02

Spoilage of low-acid canned food during prolonged storage at high temperatures is caused by heat resistant thermophilic spores of strict or facultative bacteria. Here, we performed a bacterial survey over two consecutive years on the processing line of a French company manufacturing canned mixed green peas and carrots. In total, 341 samples were collected, including raw vegetables, green peas and carrots at different steps of processing, cover brine, and process environment samples. Thermophilic and highly-heat-resistant thermophilic spores growing anaerobically were counted. During vegetable preparation, anaerobic spore counts were significantly decreased, and tended to remain unchanged further downstream in the process. Large variation of spore levels in products immediately before the sterilization process could be explained by occasionally high spore levels on surfaces and in debris of vegetable combined with long residence times in conditions suitable for growth and sporulation. Vegetable processing was also associated with an increase in the prevalence of highly-heat-resistant species, probably due to cross-contamination of peas via blanching water. Geobacillus stearothermophilus M13-PCR genotypic profiling on 112 isolates determined 23 profile-types and confirmed process-driven cross-contamination. Taken together, these findings clarify the scheme of contamination pathway by thermophilic spore-forming bacteria in a vegetable cannery. Copyright © 2015 Elsevier B.V. All rights reserved.

Effectiveness of oral antibiotics for definitive therapy of Gram-negative bloodstream infections.

Science.gov (United States)

Kutob, Leila F; Justo, Julie Ann; Bookstaver, P Brandon; Kohn, Joseph; Albrecht, Helmut; Al-Hasan, Majdi N

2016-11-01

There is paucity of data evaluating intravenous-to-oral antibiotic switch options for Gram-negative bloodstream infections (BSIs). This retrospective cohort study examined the effectiveness of oral antibiotics for definitive treatment of Gram-negative BSI. Patients with Gram-negative BSI hospitalised for antibiotics were included in this study. The cohort was stratified into three groups based on bioavailability of oral antibiotics prescribed (high, ≥95%; moderate, 75-94%; and low, antibiotics were prescribed to 106, 179 and 77 patients, respectively, for definitive therapy of Gram-negative BSI. Mean patient age was 63 years, 217 (59.9%) were women and 254 (70.2%) had a urinary source of infection. Treatment failure rates were 2%, 12% and 14% in patients receiving oral antibiotics with high, moderate and low bioavailability, respectively (P = 0.02). Risk of treatment failure in the multivariate Cox model was higher in patients receiving antibiotics with moderate [adjusted hazard ratio (aHR) = 5.9, 95% CI 1.6-38.5; P = 0.005] and low bioavailability (aHR = 7.7, 95% CI 1.9-51.5; P = 0.003) compared with those receiving oral antimicrobial agents with high bioavailability. These data demonstrate the effectiveness of oral antibiotics with high bioavailability for definitive therapy of Gram-negative BSI. Risk of treatment failure increases as bioavailability of the oral regimen declines. Copyright © 2016 Elsevier B.V. and International Society of Chemotherapy. All rights reserved.

Biofilms Formed by Gram-Negative Bacteria Undergo Increased Lipid A Palmitoylation, Enhancing In Vivo Survival

Science.gov (United States)

Chalabaev, Sabina; Chauhan, Ashwini; Novikov, Alexey; Iyer, Pavithra; Szczesny, Magdalena; Beloin, Christophe; Caroff, Martine

2014-01-01

ABSTRACT Bacterial biofilm communities are associated with profound physiological changes that lead to novel properties compared to the properties of individual (planktonic) bacteria. The study of biofilm-associated phenotypes is an essential step toward control of deleterious effects of pathogenic biofilms. Here we investigated lipopolysaccharide (LPS) structural modifications in Escherichia coli biofilm bacteria, and we showed that all tested commensal and pathogenic E. coli biofilm bacteria display LPS modifications corresponding to an increased level of incorporation of palmitate acyl chain (palmitoylation) into lipid A compared to planktonic bacteria. Genetic analysis showed that lipid A palmitoylation in biofilms is mediated by the PagP enzyme, which is regulated by the histone-like protein repressor H-NS and the SlyA regulator. While lipid A palmitoylation does not influence bacterial adhesion, it weakens inflammatory response and enhances resistance to some antimicrobial peptides. Moreover, we showed that lipid A palmitoylation increases in vivo survival of biofilm bacteria in a clinically relevant model of catheter infection, potentially contributing to biofilm tolerance to host immune defenses. The widespread occurrence of increased lipid A palmitoylation in biofilms formed by all tested bacteria suggests that it constitutes a new biofilm-associated phenotype in Gram-negative bacteria. PMID:25139899

Shape-engineered epitaxial InGaAs quantum rods for laser applications

International Nuclear Information System (INIS)

Li, L. H.; Ridha, P.; Chauvin, N.; Fiore, A.; Patriarche, G.

2008-01-01

We apply artificial shape engineering of epitaxial semiconductor nanostructures to demonstrate InGaAs quantum rods (QRs), nanocandles, and quantum dots-in-rods on a GaAs substrate. The evolution of the QRs from a zero-dimensional to one-dimensional confinement is evidenced by systematically measuring the photoluminescence and photoluminescence decay as a function of the rod length. Lasers based on a three-stack QR active region are demonstrated at room temperature, validating the applicability of the QRs in the real devices

Isolation and molecular detection of Pasteurella multocida Type A from naturally infected chickens, and their histopathological evaluation in artificially infected chickens in Bangladesh

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Sayedun Nahar Panna

2015-09-01

Full Text Available Pasteurella multocida type A is the etiologic agent of fowl cholera, a highly contagious and fatal disease of chickens. The present research work was performed for the isolation, identification and molecular detection of P. multocida Type A from chickens. Liver, heart and spleen of suspected dead chicken (n=35 were collected from Gazipur and Pabna districts in Bangladesh. The targeted bacteria from the samples were isolated, identified and characterized based on their morphology, staining, cultural, biochemical characters, pathogenicity test, histopathological study and Polymerase Chain Reaction (PCR. The P. multocida organism was isolated from 11.42% (n=4/35 samples. The organisms were gram negative, non-spore forming rod, non-motile, occurring singly or pairs in Gram staining, whereas in Leishman's stain, bipolar shaped organisms were observed. All the isolates were found positive for oxidase and catalase tests, produced indole, and fermented glucose, mannitol and sucrose. Necrotic foci in liver and congestion with hemorrhages in heart were found on necropsy. After pathogenicity test, the pathological changes were reconfirmed by histopathology depicting congestion, hemorrhage and lymphocyte infiltration in heart, liver and spleen tissues. In type specific PCR reaction, the organisms were confirmed as P. multocida Type A. In conclusion, P. multocida type A is prevalent among poultry in the studied regions; thus, care must be taken to control of the disease. [J Adv Vet Anim Res 2015; 2(3.000: 338-345

Microbiological possibilities to demonstrate that strawberries have been irradiated

International Nuclear Information System (INIS)

Tamminga, S.K.; Beumer, R.R.; Kampelmacher, E.H.

1975-01-01

Samples of greenhouse and outdoor-grown strawberries were divided into two portions, they were wrapped and one portion was irradiated at 200 krad. The composition of the microflora before and after irradiation was investigated. The flora of the non-irradiated samples was composed mainly of gram-negative rod-shaped bacteria belonging, with only a few exceptions, either to the Enterobacteriaceae-family or to the genus Pseudomonas. Also, moulds and yeasts were frequently encountered in varying quantities. Moulds and yeasts did not appear to make good indicator organisms. Gram-negative rod-shaped bacteria were always found to be absent after irradiation when solid media were used, even when starting from samples with numbers in the order of magnitude 10 5 -10 6 /gm. When outdoor-grown strawberries were used, this always led to a clear difference from the cooresponding untreated samples. Greenhouse strawberries, however, sometimes contain, even if they have not been treated, only a very small number of micro-organisms. Consequently, if gram-negative rod-shaped bacteria are present on strawberries they most probably have not been irradiated. Of course, this does not apply if post-contamination has been possible. If there is no growth of the above mentioned bacteria on any of te media used, considerable possibility exists that irradiation has taken place. (orig./MG) [de

Widespread Fosfomycin Resistance in Gram-Negative Bacteria Attributable to the Chromosomal fosA Gene

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Ryota Ito

2017-08-01

Full Text Available Fosfomycin is a decades-old antibiotic which is being revisited because of its perceived activity against many extensively drug-resistant Gram-negative pathogens. FosA proteins are Mn2+ and K+-dependent glutathione S-transferases which confer fosfomycin resistance in Gram-negative bacteria by conjugation of glutathione to the antibiotic. Plasmid-borne fosA variants have been reported in fosfomycin-resistant Escherichia coli strains. However, the prevalence and distribution of fosA in other Gram-negative bacteria are not known. We systematically surveyed the presence of fosA in Gram-negative bacteria in over 18,000 published genomes from 18 Gram-negative species and investigated their contribution to fosfomycin resistance. We show that FosA homologues are present in the majority of genomes in some species (e.g., Klebsiella spp., Enterobacter spp., Serratia marcescens, and Pseudomonas aeruginosa, whereas they are largely absent in others (e.g., E. coli, Acinetobacter baumannii, and Burkholderia cepacia. FosA proteins in different bacterial pathogens are highly divergent, but key amino acid residues in the active site are conserved. Chromosomal fosA genes conferred high-level fosfomycin resistance when expressed in E. coli, and deletion of chromosomal fosA in S. marcescens eliminated fosfomycin resistance. Our results indicate that FosA is encoded by clinically relevant Gram-negative species and contributes to intrinsic fosfomycin resistance.

Detection and differentiation of bacterial spores in a mineral matrix by Fourier transform infrared spectroscopy (FTIR and chemometrical data treatment

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Brandes Ammann Andrea

2011-07-01

Full Text Available Abstract Background Fourier transform infrared spectroscopy (FTIR has been used as analytical tool in chemistry for many years. In addition, FTIR can also be applied as a rapid and non-invasive method to detect and identify microorganisms. The specific and fingerprint-like spectra allow - under optimal conditions - discrimination down to the species level. The aim of this study was to develop a fast and reproducible non-molecular method to differentiate pure samples of Bacillus spores originating from different species as well as to identify spores in a simple matrix, such as the clay mineral, bentonite. Results We investigated spores from pure cultures of seven different Bacillus species by FTIR in reflection or transmission mode followed by chemometrical data treatment. All species investigated (B. atrophaeus, B. brevis, B. circulans, B. lentus, B. megaterium, B. subtilis, B. thuringiensis are typical aerobic soil-borne spore formers. Additionally, a solid matrix (bentonite and mixtures of benonite with spores of B. megaterium at various wt/wt ratios were included in the study. Both hierarchical cluster analysis and principal component analysis of the spectra along with multidimensional scaling allowed the discrimination of different species and spore-matrix-mixtures. Conclusions Our results show that FTIR spectroscopy is a fast method for species-level discrimination of Bacillus spores. Spores were still detectable in the presence of the clay mineral bentonite. Even a tenfold excess of bentonite (corresponding to 2.1 × 1010 colony forming units per gram of mineral matrix still resulted in an unambiguous identification of B. megaterium spores.

A neuroanatomical and physiological study of the non-image forming visual system of the cone-rod homeobox gene (Crx) knock out mouse

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Rovsing, Louise; Rath, Martin F; Lund-Andersen, Casper

2010-01-01

The anatomy and physiology of the non-image forming visual system was investigated in a visually blind cone-rod homeobox gene (Crx) knock-out mouse (Crx(-)(/)(-)), which lacks the outer segments of the photoreceptors. We show that the suprachiasmatic nuclei (SCN) in the Crx(-/-) mouse exhibit...... melanopsin neurons or the SCN may be necessary for a normal function of the non-image forming system of the mouse. However, a change in the SCN of the Crx(-/-) mouse might also explain the observed circadian differences between the knock out mouse and wild type mouse....

DNA fingerprinting of spore-forming bacterial isolates, using Bacillus ...

African Journals Online (AJOL)

Bc-repetitive extragenic palindromic polymerase chain reaction (Bc-Rep PCR) analysis was conducted on seven Bacillus thuringiensis isolates accessed from the Deutsche Sammlung von Mikroorganismen und Zellkulturen (DSMZ) culture collection and on five local isolates of entomopathogenic spore-forming bacteria.

Prevalence of Gram-negative Pathogens and their antimicrobial ...

African Journals Online (AJOL)

The present study was conducted to find out the prevalence and spectrum of Gram negative pathogens causing bacterial meningitis and their antimicrobial susceptibility pattern in a tertiary care hospital. The cerebrospinal fluid (CSF) (3-5 ml) was collected from 638 admitted children clinically suspected of septic meningitis.

Sinus surgery postpones chronic gram-negative lung infection

DEFF Research Database (Denmark)

Alanin, M C; Aanaes, K; Høiby, N

2016-01-01

Background: In patients with cystic fibrosis (CF) the sinuses are a bacterial reservoir for Gram-negative bacteria (GNB). From the sinuses the GNB can repeatedly migrate to the lungs. In a one-year follow-up study, endoscopic sinus surgery (ESS) with adjuvant therapy reduced the frequency...

Black-pigmented gram-negative anaerobes in endodontic infections.

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Haapasalo, M

1993-03-01

Necrotic dental root canal infections are polymicrobial infections dominated by anaerobic bacteria. The number of different species in one canal is usually low, approx. 4-7 species. The species isolated most frequently belong to the genera Prevotella, Porphyromonas, Fusobacterium, Peptostreptococcus, Eubacterium and Streptococcus. The frequency of isolation of black-pigmented Gram-negative anaerobes in endodontic infections varies from 25% to > 50%. Pr. intermedia is the most commonly found pigmented species, followed by Pr. denticola and two Porphyromonas species, P. gingivalis and P. endodontalis. Several studies have shown that P. gingivalis and P. endodontalis are closely related to the presence of acute symptoms in endodontic infections, whereas other black-pigmented Gram-negative anaerobes are not. However, several other species may also be involved in acute infections. Moreover, Porphyromonas species have occasionally been isolated from cases with no symptoms. Although Porphyromonas spp. are clearly related to symptoms at the beginning of therapy, they are not important for the prognosis of the treatment.

Breaking barriers: expansion of the use of endolysins as novel antibacterials against Gram-negative bacteria.

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Briers, Yves; Lavigne, Rob

2015-01-01

The emergence and spread of antibiotic-resistant bacteria drives the search for novel classes of antibiotics to replenish our armamentarium against bacterial infections. This is particularly critical for Gram-negative pathogens, which are intrinsically resistant to many existing classes of antibiotics due to the presence of a protective outer membrane. In addition, the antibiotics development pipeline is mainly oriented to Gram-positive pathogens such as methicillin-resistant Staphylococcus aureus. A promising novel class of antibacterials is endolysins. These enzymes encoded by bacterial viruses hydrolyze the peptidoglycan layer with high efficiency, resulting in abrupt osmotic lysis and cell death. Their potential as novel antibacterials to treat Gram-positive bacteria has been extensively demonstrated; however, the Gram-negative outer membrane has presented a formidable barrier for the use of endolysins against Gram-negatives until recently. This review reports on the most recent advances in the development of endolysins to kill Gram-negative species with a special focus on endolysin-engineered Artilysins(®).

Inhaled Antibiotics for Gram-Negative Respiratory Infections

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Fraidenburg, Dustin R.; Scardina, Tonya

2016-01-01

SUMMARY Gram-negative organisms comprise a large portion of the pathogens responsible for lower respiratory tract infections, especially those that are nosocomially acquired, and the rate of antibiotic resistance among these organisms continues to rise. Systemically administered antibiotics used to treat these infections often have poor penetration into the lung parenchyma and narrow therapeutic windows between efficacy and toxicity. The use of inhaled antibiotics allows for maximization of target site concentrations and optimization of pharmacokinetic/pharmacodynamic indices while minimizing systemic exposure and toxicity. This review is a comprehensive discussion of formulation and drug delivery aspects, in vitro and microbiological considerations, pharmacokinetics, and clinical outcomes with inhaled antibiotics as they apply to disease states other than cystic fibrosis. In reviewing the literature surrounding the use of inhaled antibiotics, we also highlight the complexities related to this route of administration and the shortcomings in the available evidence. The lack of novel anti-Gram-negative antibiotics in the developmental pipeline will encourage the innovative use of our existing agents, and the inhaled route is one that deserves to be further studied and adopted in the clinical arena. PMID:27226088

Resistance trends in gram-negative bacteria: surveillance results from two Mexican hospitals, 2005–2010

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Morfin-Otero Rayo

2012-06-01

Full Text Available Abstract Background Hospital-acquired infections caused by multiresistant gram-negative bacteria are difficult to treat and cause high rates of morbidity and mortality. The analysis of antimicrobial resistance trends of gram-negative pathogens isolated from hospital-acquired infections is important for the development of antimicrobial stewardship programs. The information obtained from antimicrobial resistant programs from two hospitals from Mexico will be helpful in the selection of empiric therapy for hospital-acquired gram-negative infections. Findings Two thousand one hundred thirty two gram-negative bacteria collected between January 2005 and December 2010 from hospital-acquired infections occurring in two teaching hospitals in Mexico were evaluated. Escherichia coli was the most frequently isolated gram-negative bacteria, with >50% of strains resistant to ciprofloxacin and levofloxacin. Klebsiella spp. showed resistance rates similar to Escherichia coli for ceftazidime (33.1% vs 33.2%, but exhibited lower rates for levofloxacin (18.2% vs 56%. Of the samples collected for the third most common gram-negative bacteria, Pseudomonas aeruginosa, >12.8% were resistant to the carbapenems, imipenem and meropenem. The highest overall resistance was found in Acinetobacter spp. Enterobacter spp. showed high susceptibility to carbapenems. Conclusions E. coli was the most common nosocomial gram-negative bacilli isolated in this study and was found to have the second-highest resistance to fluoroquinolones (>57.9%, after Acinetobacter spp. 81.2%. This finding represents a disturbing development in a common nosocomial and community pathogen.

Isolation and characterization of a mesophilic heavy-metals-tolerant sulfate-reducing bacterium Desulfomicrobium sp. from an enrichment culture using phosphogypsum as a sulfate source

International Nuclear Information System (INIS)

Azabou, Samia; Mechichi, Tahar; Patel, Bharat K.C.; Sayadi, Sami

2007-01-01

A sulfate-reducing bacterium, was isolated from a 6 month trained enrichment culture in an anaerobic media containing phosphogypsum as a sulfate source, and, designated strain SA2. Cells of strain SA2 were rod-shaped, did not form spores and stained Gram-negative. Phylogenetic analysis of the 16S rRNA gene sequence of the isolate revealed that it was related to members of the genus Desulfomicrobium (average sequence similarity of 98%) with Desulfomicrobium baculatum being the most closely related (sequence similarity of 99%). Strain SA2 used thiosulfate, sulfate, sulfite and elemental sulfur as electron acceptors and produced sulfide. Strain SA2 reduced sulfate contained in 1-20 g/L phosphogypsum to sulfide with reduction of sulfate contained in 2 g/L phosphogypsum being the optimum concentration. Strain SA2 grew with metalloid, halogenated and non-metal ions present in phosphogypsum and with added high concentrations of heavy metals (125 ppm Zn and 100 ppm Ni, W, Li and Al). The relative order for the inhibitory metal concentrations, based on the IC 50 values, was Cu, Te > Cd > Fe, Co, Mn > F, Se > Ni, Al, Li > Zn

Enterobacter siamensis sp. nov., a transglutaminase-producing bacterium isolated from seafood processing wastewater in Thailand.

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Khunthongpan, Suwannee; Bourneow, Chaiwut; H-Kittikun, Aran; Tanasupawat, Somboon; Benjakul, Soottawat; Sumpavapol, Punnanee

2013-01-01

A novel strain of Enterobacter, C2361(T), a Gram-negative, non-spore-forming, rod-shaped and facultative anaerobic bacterium with the capability to produce transglutaminase, was isolated from seafood processing wastewater collected from a treatment pond of a seafood factory in Songkhla Province, Thailand. Phylogenetic analyses and phenotypic characteristics, including chemotaxonomic characteristics, showed that the strain was a member of the genus Enterobacter. The 16S rRNA gene sequence similarities between strain C2361(T) and Enterobacter cloacae subsp. cloacae ATCC 13047(T) and Enterobacter cloacae subsp. dissolvens LMG 2683(T) were 97.5 and 97.5%, respectively. Strain C2361(T) showed a low DNA-DNA relatedness with the above-mentioned species. The major fatty acids were C16:0, C17:0cyclo and C14:0. The DNA G+C content was 53.0 mol%. On the basis of the polyphasic evidence gathered in this study, it should be classified as a novel species of the genus Enterobacter for which the name Enterobacter siamensis sp. nov. is proposed. The type strain is C2361(T) (= KCTC 23282(T) = NBRC 107138(T)).

A Synthetic Dual Drug Sideromycin Induces Gram-Negative Bacteria To Commit Suicide with a Gram-Positive Antibiotic.

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Liu, Rui; Miller, Patricia A; Vakulenko, Sergei B; Stewart, Nichole K; Boggess, William C; Miller, Marvin J

2018-05-10

Many antibiotics lack activity against Gram-negative bacteria because they cannot permeate the outer membrane or suffer from efflux and, in the case of β-lactams, are degraded by β-lactamases. Herein, we describe the synthesis and studies of a dual drug conjugate (1) of a siderophore linked to a cephalosporin with an attached oxazolidinone. The cephalosporin component of 1 is rapidly hydrolyzed by purified ADC-1 β-lactamase to release the oxazolidinone. Conjugate 1 is active against clinical isolates of Acinetobacter baumannii as well as strains producing large amounts of ADC-1 β-lactamase. Overall, the results are consistent with siderophore-mediated active uptake, inherent activity of the delivered dual drug, and in the presence of β-lactamases, intracellular release of the oxazolidinone upon cleavage of the cephalosporin to allow the freed oxazolidinone to inactivate its target. The ultimate result demonstrates that Gram-positive oxazolidinone antibiotics can be made to be effective against Gram-negative bacteria by β-lactamase triggered release.

[Endocarditis due to Aggregatibacter (formerly: Actinobacillus) actinomycetemcomitans, a bacterium that grows in characteristic star-shaped colonies].

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Lampe, A S; Schroijen, M A; Smith, S J

2008-04-05

A 72-year-old man, having had an artificial valve for almost 20 years now, presented with tiredness that had persisted for several weeks and reported weight loss of 5 kg. In more recent days he experienced fever and cold shivers, and an associated dry cough. Bearing in mind the potential for endocarditis, blood cultures were grown. In this, we identified a small, Gram-negative rod with a small, smooth, raised colony that grew slowly. We considered a micro-organism from the 'HACEK group', which is a group of micro-organisms including Haemophilus aphrophilus, Haemophilus paraphrophilus, Cardiobacterium hominis, Eikenella corrodens, Kingella kingae and Aggregatibacter (formerly: Actinobacillus) actinomycetemcomitans. More careful observation revealed that the bacteria formed star-shaped colonies, proving that A. actinomycetemcomitans was the cause of this non-acute endocarditis. The patient received antibiotic treatment. Because non-acute endocarditis is often caused by hidden abnormalities in the mouth or teeth and A. actinomycetemcomitans plays an important role in severe cases of peridontitis, a dental surgeon was consulted. The dental surgeon diagnosed multifocal peridontitis and treated the patient, who was able to leave the hospital after 6 weeks of antibiotic treatment.

Multiparametric Profiling for Identification of Chemosensitizers against Gram-Negative Bacteria

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Vincent Lôme

2018-02-01

Full Text Available Antibiotic resistance is now a worldwide therapeutic problem. Since the beginning of anti-infectious treatment bacteria have rapidly shown an incredible ability to develop and transfer resistance mechanisms. In the last decades, the design variation of pioneer bioactive molecules has strongly improved their activity and the pharmaceutical companies partly won the race against the clock. Since the 1980s, the new classes of antibiotics that emerged were mainly directed to Gram-positive bacteria. Thus, we are now facing to multidrug-resistant Gram-negative bacteria, with no therapeutic options to deal with them. These bacteria are mainly resistant because of their double membrane that conjointly impairs antibiotic accumulation and extrudes these molecules when entered. The main challenge is to allow antibiotics to cross the impermeable envelope and reach their targets. One promising solution would be to associate, in a combination therapy, a usual antibiotic with a non-antibiotic chemosensitizer. Nevertheless, for effective drug discovery, there is a prominent lack of tools required to understand the rules of permeation and accumulation into Gram-negative bacteria. By the use of a multidrug-resistant enterobacteria, we introduce a high-content screening procedure for chemosensitizers discovery by quantitative assessment of drug accumulation, alteration of barriers, and deduction of their activity profile. We assembled and analyzed a control chemicals library to perform the proof of concept. The analysis was based on real-time monitoring of the efflux alteration and measure of the influx increase in the presence of studied compounds in an automatized bio-assay. Then, synergistic activity of compounds with an antibiotic was studied and kinetic data reduction was performed which led to the calculation of a score for each barrier to be altered.

Detection of Extended Spectrum Beta-Lactamases Among Gram Negative Bacilli Recovered from Cattle Feces In Benin City, Nigeria

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Helen Oroboghae OGEFERE

2017-06-01

Full Text Available This study was carried out to determine the prevalence of extended spectrum beta-lactamase (ESBL among Gram negative bacteria isolated from cattle feces in Benin City, Nigeria. A total of 250 Gram negative bacteria isolates were recovered from cattle feces and were processed microbiologically using standard techniques. Emergent colonies were identified and antibacterial susceptibility tests were determined using Kirby-Bauer disk diffusion method. All bacterial isolates were screened for the presence of ESBL using the double-disc synergy method. A total of 37 (14.8% isolates were positive for ESBL, with 33 (13.2% indicated by ceftazidime, while only 4 (1.6% were indicated by both ceftazidime and cefotaxime (P < 0.0001. Of the Gram negative bacterial isolates recovered, Salmonella species was the most prevalent ESBL-producer with 55.0% prevalence (P = 0.0092, while no isolate of Pseudomonas aeruginosa produced ESBL. ESBL-positive isolates showed poor susceptibility to the tested antibacterial agents in comparison with non-ESBL-producers and imipenem was the most active antibiotic. The prevalence of ESBL among Gram negative bacilli recovered from cattle feces was 14.8%. The study advises prudent use of antibiotics in the treatment of cattle and harps on improved hygiene in managing cattle, as they are potential reservoirs of ESBL-producing organisms.

[Influence of serious infections due to Gram-negative bacteria on the hospital economy].

Science.gov (United States)

Martínez, B; Gómez, J; Gómez Vargas, J; Guerra, B; Ruiz Gómez, J; Simarro, E; Baños, V; Canteras, M; Valdes, M

2000-12-01

Nosocomial infections due to Gram-negative bacteria are very important since they are associated with high morbidity and high hospital costs. A prospective study of 250 inpatients was carried out, 200 of whom had Gram-negative bacterial infections. Patients were divided into groups of 50 according to the localization of the infection (urinary, surgical wound, respiratory tract and bacteremia), with a control group of 50 patients with similar characteristics but no infection. We calculated the cost for the different groups by multiplying the average length of hospital stay in days by the daily cost of the stay. Significant differences were observed in the average length of stay per patient according to the type of infection and how it was acquired. In terms of cost, nosocomial infection due to Gram-negative bacteria was 1,049,139 pesetas more expensive than community-acquired infection. The cost of the stay for patients with postsurgical infection due to Gram-negative bacteria was 1,108, 252 pesetas more expensive than for the group of control patients. Nosocomial infection due to Gram-negative bacteria is associated with a prolongation in hospital stay of 9 to 28 days, which is the factor that most reflects the cost that can be attributed to nosocomial infection. Consensual and protocolized measures which allow for better clinical management need to be developed.

CRC DEPLETION CALCULATIONS FOR THE NON-RODDED ASSEMBLIES IN BATCHES 8 AND 9 CRYSTAL RIVER UNIT 3

International Nuclear Information System (INIS)

Wilson, Michael L.

2001-01-01

The purpose of this design analysis is to document the SAS2H depletion calculations of certain non-rodded fuel assemblies from batches 8 and 9 of the Crystal River Unit 3 pressurized water reactor (PWR) that are required for Commercial Reactor Critical (CRC) evaluations to support the development of the disposal criticality methodology. A non-rodded assembly is one which never contains a control rod assembly (CRA) or an axial power shaping rod assembly (APSRA) during its irradiation history. The objective of this analysis is to provide SAS2H generated isotopic compositions for each fuel assembly's depleted fuel and depleted burnable poison materials. These SAS2H generated isotopic compositions are acceptable for use in CRC benchmark reactivity calculations containing the various fuel assemblies

Changing epidemiology of central venous catheter-related bloodstream infections: increasing prevalence of Gram-negative pathogens.

Science.gov (United States)

Marcos, Miguel; Soriano, Alex; Iñurrieta, Amaia; Martínez, José A; Romero, Alberto; Cobos, Nazaret; Hernández, Cristina; Almela, Manel; Marco, Francesc; Mensa, Josep

2011-09-01

Gram-positive microorganisms have been the predominant pathogens in central venous catheter-related bloodstream infections (CRBSIs). Recent guidelines recommend empirical therapy according to this and restrict coverage for Gram-negatives to specific circumstances. This study aimed to analyse the epidemiological changes in CRBSIs over the 1991-2008 period and to analyse predictors of Gram-negative CRBSIs. A prospectively collected cohort of patients with confirmed CRBSIs was analysed. Strains isolated and antimicrobial susceptibility, as well as clinical and demographic variables were recorded. Differences observed during the study period were analysed by means of a χ² trend test and factors associated with Gram-negative CRBSIs by means of multivariable analysis. Between 1991 and 2008, 1129 episodes of monomicrobial CRBSIs were recorded. There was an increase in the incidence of CRBSIs, from 0.10 (1991-92) to 0.31 (2007-08) episodes/1000 patient-days. A significant increase in the number of Gram-negative strains among the total isolates was also found, from 3 (4.7%) in 1991-92 to 70 (40.23%) in 2007-08, with a parallel decrease in the percentage of Gram-positives. Solid organ transplantation, prior use of penicillins and hospital stay longer than 11 days were independently associated with a significantly higher risk of Gram-negative CRBSIs, while cirrhosis, diabetes and use of quinolones were associated with a higher risk of Gram-positives. Gram-negative strains are an increasing cause of CRBSIs, reaching a prevalence of 40% in the 2007-08 period in our hospital. If this trend is confirmed in other centres, a broad-spectrum empirical therapy should be considered in managing these infections.

Community-acquired multidrug-resistant Gram-negative bacterial infective endocarditis.

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Naha, Sowjanya; Naha, Kushal; Acharya, Vasudev; Hande, H Manjunath; Vivek, G

2014-08-05

We describe two cases of bacterial endocarditis secondary to multidrug-resistant Gram-negative organisms. In both cases, the diagnosis was made in accordance with the modified Duke's criteria and confirmed by histopathological analysis. Furthermore, in both instances there were no identifiable sources of bacteraemia and no history of contact with hospital or other medical services prior to the onset of symptoms. The patients were managed in similar fashion with prolonged broad-spectrum antibiotic therapy and surgical intervention and made complete recoveries. These cases highlight Gram-negative organisms as potential agents for endocarditis, as well as expose the dissemination of such multidrug-resistant bacteria into the community. The application of an integrated medical and surgical approach and therapeutic dilemmas encountered in managing these cases are described. 2014 BMJ Publishing Group Ltd.

Beta-lactam resistance in the gram negatives: increasing complexity of conditional, composite and multiply resistant phenotypes.

Science.gov (United States)

Iredell, Jon; Thomas, Lee; Espedido, Björn

2006-12-01

The greatest impact of microbiology data on clinical care is in the critically ill. Unfortunately, this is also the area in which microbiology laboratories are most often non-contributive. Attempts to move to rapid, culture-independent diagnostics are driven by the need to expedite urgent results. This is difficult in Gram-negative infection because of the complexity of the antibiotic resistance phenotype. Here, we discuss resistance to modern beta-lactams as a case in point. Recent outbreaks of transmissible carbapenem resistance among Gram-negative enteric pathogens in Sydney and Melbourne serve to illustrate the pitfalls of traditional phenotypical approaches. A better understanding of the epidemiology and mosaic nature of antibiotic resistance elements in the microflora is needed for us to move forward.

Gram-negative folliculitis. A rare problem or is it underdiagnosed? Case report and literature review

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Sierra-Téllez Daniela, Ponce-Olivera Rosa María, Tirado-Sánchez Andrés

2011-07-01

Full Text Available AbstractGram-negative folliculitis may be the result of prolonged antibacterial treatments in patients with acne and rosacea. It is caused by alteration of facial skin flora and the nasal mucous, a decrease of Gram-positive bacteria and a proliferation of Gram-negative bacteria (for example Escherichia coli, Pseudomonas aeruginosa, Serratia marcescens, Klebsiella sp. and Proteus mirabilis. It should be considered in patients with acne who have not had a clinical improvement after 3-6 months of treatment with tetracyclines. The disease is underestimated, probably because bacteriological studies are rarely requested and the increased use of oral isotretinoin for acne management. One of the most effective treatments for Gram-negative folliculitis is oral isotretinoin (0.5-1 mg / kg / day for 4-5 months. We report the case of Gram negative folliculitis successfully treated with oral isotretinoin.

Parapedobacter koreensis gen. nov., sp. nov.

Science.gov (United States)

Kim, Myung Kyum; Na, Ju-Ryun; Cho, Dong Ha; Soung, Nak-Kyun; Yang, Deok-Chun

2007-06-01

Strain Jip14(T), a Gram-negative, non-spore-forming, rod-shaped, non-motile bacterium, was isolated from dried rice straw and characterized in order to determine its taxonomic position. 16S rRNA gene sequence analysis revealed that strain Jip14(T) belongs to the family Sphingobacteriaceae, and the highest degree of sequence similarity was determined to be to Pedobacter saltans DSM 12145(T) (88.5 %), Pedobacter africanus DSM 12126(T) (87.6 %), Pedobacter heparinus DSM 2366(T) (87.1 %) and Pedobacter caeni LMG 22862(T) (86.9 %). Chemotaxonomic data revealed that strain Jip14(T) possesses menaquinone MK-7 and the predominant fatty acids C(15 : 0) iso, C(16 : 0), C(16 : 0) 10-methyl, C(17 : 0) iso 3-OH and summed feature 3 (C(15 : 0) iso 2-OH/C(16 : 1)omega7c). The results of physiological and biochemical tests clearly demonstrated that strain Jip14(T) represents a distinct species. Based on these data, Jip14(T) should be classified within a novel genus and species, for which the name Parapedobacter koreensis gen. nov., sp. nov. is proposed. The type strain of Parapedobacter koreensis is Jip14(T) (=KCTC 12643(T)=LMG 23493(T)).

Feasibility of flotation concentration of fungal spores as a method to identify toxigenic mushrooms

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Bazzle LJ

2014-12-01

97.5% of trials. The most common spore shapes observed were globose, spiked, elliptical, smooth and reticulate. Conclusion: Flotation can concentrate mushroom spores; however, false negative results can occur. Spore morphology could not be used to differentiate species of mushroom-forming fungi since the spore shape and surface characteristics seen in the present study were often observed with multiple species of mushroom-forming fungi. Keywords: gastrointestinal contents, mushroom spore identification, mushroom toxicity, Amanita spp.

Lysinibacillus louembei sp. nov., a spore-forming bacterium isolated from Ntoba Mbodi, alkaline fermented leaves of cassava from the Republic of the Congo

DEFF Research Database (Denmark)

Ouoba, Labia Irène I.; Mbozo, Alain B. Vouidibio; Thorsen, Line

2015-01-01

. xylanilyticus DSM 23493T and L. odysseyi DSM 18869T was 41%, 16% and 15%, respectively. The internal transcribed spacer-PCR profile of the isolate was different from those of closely related bacteria. The cellwall peptidoglycan type was A4α, L-Lys-D-Asp and the major fatty acids were iso-C15:0, anteiso-C15......Investigation of the microbial diversity of Ntoba Mbodi, an African food made from the alkaline fermentation of cassava leaves, revealed the presence of a Gram-positive, catalase-positive, aerobic, motile and rod-shaped endospore-forming bacterium (NM73) with unusual phenotypic and genotypic......:0, anteiso-C17:0 and iso-C17:0 and iso-C17:1ω10c. The polar lipids included phosphatidylethanolamine, diphosphatidylglycerol, phosphatidylglycerol, phosphoaminolipid, aminolipid, two phospholipids and two unknown lipids. The predominant menaquinones were MK-7 and MK-6.Ribose was the only whole-cell sugar...

Biosynthesis and recovery of rod-shaped tellurium nanoparticles and their bactericidal activities

Energy Technology Data Exchange (ETDEWEB)

Zare, Bijan; Faramarzi, Mohammad Ali; Sepehrizadeh, Zargham [Department of Pharmaceutical Biotechnology and Biotechnology Research Center, Faculty of Pharmacy, Tehran University of Medical Sciences, P.O. Box 14155-6451 Tehran (Iran, Islamic Republic of); Shakibaie, Mojtaba [Department of Pharmacognosy and Biotechnology, School of Pharmacy, Pharmaceutics Research Center, Kerman University of Medical Sciences, P.O. Box 76175-493 Kerman (Iran, Islamic Republic of); Rezaie, Sassan [Department of Medical Biotechnology, School of Advanced Medical Technologies, Tehran University of Medical Sciences, Tehran (Iran, Islamic Republic of); Shahverdi, Ahmad Reza, E-mail: shahverd@sina.tums.ac.ir [Department of Pharmaceutical Biotechnology and Biotechnology Research Center, Faculty of Pharmacy, Tehran University of Medical Sciences, P.O. Box 14155-6451 Tehran (Iran, Islamic Republic of)

2012-11-15

Highlights: ► Biosynthesis of rod shape tellurium nanoparticles with a hexagonal crystal structure. ► Extraction procedure for isolation of tellurium nanoparticles from Bacillus sp. BZ. ► Extracted tellurium nanoparticles have good bactericidal activity against some bacteria. -- Abstract: In this study, a tellurium-transforming Bacillus sp. BZ was isolated from the Caspian Sea in northern Iran. The isolate was identified by various tests and 16S rDNA analysis, and then used to prepare elemental tellurium nanoparticles. The isolate was subsequently used for the intracellular biosynthesis of elemental tellurium nanoparticles. The biogenic nanoparticles were released by liquid nitrogen and purified by an n-octyl alcohol water extraction system. The shape, size, and composition of the extracted nanoparticles were characterized. The transmission electron micrograph showed rod-shaped nanoparticles with dimensions of about 20 nm × 180 nm. The energy dispersive X-ray and X-ray diffraction spectra respectively demonstrated that the extracted nanoparticles consisted of only tellurium and have a hexagonal crystal structure. This is the first study to demonstrate a biological method for synthesizing rod-shaped elemental tellurium by a Bacillus sp., its extraction and its antibacterial activity against different clinical isolates.

Biosynthesis and recovery of rod-shaped tellurium nanoparticles and their bactericidal activities

International Nuclear Information System (INIS)

Zare, Bijan; Faramarzi, Mohammad Ali; Sepehrizadeh, Zargham; Shakibaie, Mojtaba; Rezaie, Sassan; Shahverdi, Ahmad Reza

2012-01-01

Highlights: ► Biosynthesis of rod shape tellurium nanoparticles with a hexagonal crystal structure. ► Extraction procedure for isolation of tellurium nanoparticles from Bacillus sp. BZ. ► Extracted tellurium nanoparticles have good bactericidal activity against some bacteria. -- Abstract: In this study, a tellurium-transforming Bacillus sp. BZ was isolated from the Caspian Sea in northern Iran. The isolate was identified by various tests and 16S rDNA analysis, and then used to prepare elemental tellurium nanoparticles. The isolate was subsequently used for the intracellular biosynthesis of elemental tellurium nanoparticles. The biogenic nanoparticles were released by liquid nitrogen and purified by an n-octyl alcohol water extraction system. The shape, size, and composition of the extracted nanoparticles were characterized. The transmission electron micrograph showed rod-shaped nanoparticles with dimensions of about 20 nm × 180 nm. The energy dispersive X-ray and X-ray diffraction spectra respectively demonstrated that the extracted nanoparticles consisted of only tellurium and have a hexagonal crystal structure. This is the first study to demonstrate a biological method for synthesizing rod-shaped elemental tellurium by a Bacillus sp., its extraction and its antibacterial activity against different clinical isolates.

SURVEILLANCE of CARBAPENEM NON-SUSCEPTIBLE GRAM NEGATIVE STRAINS and CHARACTERIZATION of CARBAPENEMASES of CLASSES A, B and D in a LEBANESE HOSPITAL.

Science.gov (United States)

Hammoudi, Dalal; Moubareck, Carole Ayoub; Kanso, Abeer; Nordmann, Patrice; Sarkis, Dolla Karam

2015-01-01

The production of carbapenem-hydrolyzing enzymes has been recognized as one of the most currently relevant resistance mechanisms in gram negative bacterial isolates, and is being detected in various countries. In Lebanon, carbapenem resistance was studied among gram negative pathogens collected from a university hospital from January to June of years 2011 and 2012. All isolates were subjected to phenotypic tests including antibiotic susceptibility, cloxacillin effect, modified Hodge test, and Etest for metallo-β-lactamase detection. They were also subjected to genotyping by PCR sequencing to characterize β-lactamases. Between January and June 2011, 48 carbapenem non-susceptible strains were collected. Of these, one Klebsiella pneumoniae harbored OXA-48 and insertion sequence IS 1999; four Acinetobacter baumanni harbored simultaneously OXA-23 and GES-11, and three Pseudomonas harbored VIM-2 carbapenemase. Between January and June 2012, 100 carbapenem non-susceptible strains were collected. Of these, one K. pneumoniae harbored simultaneously OXA-48, IS 1999, and an acquired AmpC of the ACC group; four Serratia marcescens harbored OXA-48, while among eight A. baumannii, one strain co-harbored OXA-23 and GES-11, six harbored OXA-23 and one OXA-24. Fifteen P, aeruginosa and two Pseudomonas species harbored VIM-2; two P. aeruginosa strains produced IMP-1 and two others IMP-2. This epidemiological survey demonstrates the presence of carbapenemases of Ambler classes A, B, and D in a Lebanese hospital and indicates increase in the number and variety of such enzymes.

Enzymes produced by halotolerant spore-forming gram-positive bacterial strains isolated from a resting habitat (Restinga de Jurubatiba) in Rio de Janeiro, Brazil: focus on proteases.

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D Santos, Anderson Fragoso; Pacheco, Clarissa Almeida; Valle, Roberta D Santos; Seldin, Lucy; D Santos, André Luis Souza

2014-12-01

The screening for hydrolases-producing, halotolerant, and spore-forming gram-positive bacteria from the root, rhizosphere, and non-rhizosphere soil of Blutaparon portulacoides, a plant found in the Restinga de Jurubatiba located at the northern region of Rio de Janeiro State, Brazil, resulted in the isolation of 22 strains. These strains were identified as Halobacillus blutaparonensis (n = 2), Oceanobacillus picturae (n = 5), and Oceanobacillus iheyensis (n = 15), and all showed the ability to produce different extracellular enzymes. A total of 20 isolates (90.9 %) showed activity for protease, 5 (22.7 %) for phytase, 3 (13.6 %) for cellulase, and 2 (9.1 %) for amylase. Some bacterial strains were capable of producing three (13.6 %) or two (9.1 %) distinct hydrolytic enzymes. However, no bacterial strain with ability to produce esterase and DNase was observed. The isolate designated M9, belonging to the species H. blutaparonensis, was the best producer of protease and also yielded amylase and phytase. This strain was chosen for further studies regarding its protease activity. The M9 strain produced similar amounts of protease when grown either without or with different NaCl concentrations (from 0.5 to 10 %). A simple inspection of the cell-free culture supernatant by gelatin-sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) revealed the presence of three major alkaline proteases of 40, 50, and 70 kDa, which were fully inhibited by phenylmethylsulfonyl fluoride (PMSF) and tosyl-L-phenylalanine chloromethyl ketone (TPCK) (two classical serine protease inhibitors). The secreted proteases were detected in a wide range of temperature (from 4 to 45 °C) and their hydrolytic activities were stimulated by NaCl (up to 10 %). The serine proteases produced by the M9 strain cleaved gelatin, casein, albumin, and hemoglobin, however, in different extensions. Collectively, these results suggest the potential use of the M9 strain in biotechnological

Antibiofilm effect of Nocardiopsis sp. GRG 1 (KT235640) compound against biofilm forming Gram negative bacteria on UTIs.

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Rajivgandhi, Govindan; Vijayan, Ramachandran; Maruthupandy, Muthuchamy; Vaseeharan, Baskaralingam; Manoharan, Natesan

2018-05-01

Urinary tract infections (UTIs) are diverse public health complication and caused by range of pathogens, however mostly Gram negative bacteria cause significant life threatening risks to different populations. The prevalence rate and antimicrobial resistance among the Gram negative uropathogens alarmed significantly heighten the economic burden of these infections. In this study, we investigated the antibiofilm efficiency of Pyrrolo [1,2-a] pyrazine-1,4-dione,hexahydro-3-(2-methylpropyl) extracted from endophytic actinomycetes Nocardiopsis sp. GRG 1 (KT235640) against P. mirabilis and E. coli. The extracted compound was characterized through TLC, HPLC, GC-MS, LC-MS and confocal laser scanning microscopy (CLSM), scanning electron microscopy (SEM). The compound, Pyrrolo [1,2-a] pyrazine-1, 4-dione, hexahydro-3-(2-methylpropyl) inhibits both bacterial biofilm formation as well as reduces the viability of preformed biofilms. Furthermore, CLSM image shows cell shrinkage, disorganized cell membrane and loss of viability. The SEM result also confirms the cell wall degradation in treated cells of the bacteria. Hence, the Pyrrolo [1,2-a]pyrazine-1,4-dione, hexahydro-3-(2-methylpropyl) is active against P. mirabilis and E. coli. Copyright © 2018 Elsevier Ltd. All rights reserved.

Spirosoma spitsbergense sp. nov. and Spirosoma luteum sp. nov., isolated from a high Arctic permafrost soil, and emended description of the genus Spirosoma

DEFF Research Database (Denmark)

Finster, Kai; Herbert, Rodney Andrew; Lomstein, Bente Aagaard

2009-01-01

Two pigmented, Gram-negative, non-motile, pleomorphic rod-shaped bacteria (strains SPM-9T and SPM-10T) were isolated from a permafrost soil collected from the Adventdalen valley, Spitsbergen, northern Norway. A third isolate (strain M5-H2) was recovered from the same soil sample after the sample ...

STUDY ON SURGICAL SITE INFECTIONS CAUSED BY ESBL PRODUCING GRAM NEGATIVE BACTERIA

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Rambabu

2015-09-01

Full Text Available Surgical site infections have been a major problem, because of the emergence of drug resistant bacteria, in particular B - lactamase producing bacteria. Extended spectrum beta lactamase producing gram negative organisms pose a great challenge in treatment o f SSI present study is aimed at determining multiple drug resistance in gram negative bacteria & to find out ESBL producers, in correlation with treatment outcome. A total of 120 wound infected cases were studied. Staphylococcus aureus was predominant bact erium - 20.Among gram negative bacteria, Pseudomonas species is predominant (14 followed by Escherichia coli (13 , Klebsiella species (12 , Proteus (9 Citrobacter (4 Providencia (2 & Acinetobacter species (2 . Out of 56 gramnegative bacteria isolated, 20 were i dentified as ESBL producers, which was statistically significant. Delay in wound healing correlated with infection by ESBL producers, which alarms the need of abstinence from antibiotic abuse

Quorum sensing in gram-negative bacteria

DEFF Research Database (Denmark)

Wu, H.; Song, Z.J.; Høiby, N.

2004-01-01

Bacteria can communicate with each other by means of signal molecules to coordinate the behavior of the entire community, and the mechanism is referred to as quorum sensing (QS). Signal systems enable bacteria to sense the size of their densities by monitoring the concentration of the signal...... molecules. Among Gram-negative bacteria N-acyl-L-homoserine lactone (acyl-HSL)-dependent quorum sensing systems are particularly widespread. These systems are used to coordinate expression of phenotypes that are fundamental to the interaction of bacteria with each other and with their environment...

A resurgence of β-lactamase inhibitor combinations effective against multidrug-resistant Gram-negative pathogens.

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Bush, Karen

2015-11-01

β-Lactamase inhibitors (BLIs) have played an important role in combatting β-lactam resistance in Gram-negative bacteria, but their effectiveness has diminished with the evolution of diverse and deleterious varieties of β-lactamases. In this review, a new generation of BLIs and inhibitor combinations is presented, describing epidemiological information, pharmacodynamic studies, resistance identification and current clinical status. Novel serine BLIs of major interest include the non-β-lactams of the diazabicyclo[3.2.1]octanone (DBO) series. The DBOs avibactam, relebactam and RG6080 inhibit most class A and class C β-lactamases, with selected inhibition of class D enzymes by avibactam. The novel boronic acid inhibitor RPX7009 has a similar inhibitory profile. All of these inhibitors are being developed in combinations that are targeting primarily carbapenemase-producing Gram-negative pathogens. Two BLI combinations (ceftolozane/tazobactam and ceftazidime/avibactam) were recently approved by the US Food and Drug Administration (FDA) under the designation of a Qualified Infectious Disease Product (QIDP). Other inhibitor combinations that have at least completed phase 1 clinical trials are ceftaroline fosamil/avibactam, aztreonam/avibactam, imipenem/relebactam, meropenem/RPX7009 and cefepime/AAI101. Although effective inhibitor combinations are in development for the treatment of infections caused by Gram-negative bacteria with serine carbapenemases, better options are still necessary for pathogens that produce metallo-β-lactamases (MBLs). The aztreonam/avibactam combination demonstrates inhibitory activity against MBL-producing enteric bacteria owing to the stability of the monobactam to these enzymes, but resistance is still an issue for MBL-producing non-fermentative bacteria. Because all of the inhibitor combinations are being developed as parenteral drugs, an orally bioavailable combination would also be of interest. Copyright © 2015 Elsevier B.V. and the

Live-imaging of Bacillus subtilis spore germination and outgrowth

NARCIS (Netherlands)

Pandey, R.

2014-01-01

Spores of Gram-positive bacteria such as Bacillus and Clostridium cause huge economic losses to the food industry. In food products, spores survive under food preservation conditions and subsequent germination and outgrowth eventually causes food spoilage. Therefore efforts are being made to

Intrinsic, adaptive and acquired antimicrobial resistance in Gram-negative bacteria.

Science.gov (United States)

Arzanlou, Mohsen; Chai, Wern Chern; Venter, Henrietta

2017-02-28

Gram-negative bacteria are responsible for a large proportion of antimicrobial-resistant infections in humans and animals. Among this class of bacteria are also some of the most successful environmental organisms. Part of this success is their adaptability to a variety of different niches, their intrinsic resistance to antimicrobial drugs and their ability to rapidly acquire resistance mechanisms. These mechanisms of resistance are not exclusive and the interplay of several mechanisms causes high levels of resistance. In this review, we explore the molecular mechanisms underlying resistance in Gram-negative organisms and how these different mechanisms enable them to survive many different stress conditions. © 2017 The Author(s). Published by Portland Press Limited on behalf of the Biochemical Society.

[Diagnostic and therapeutic management of Gram-negative infections].

Science.gov (United States)

Bassetti, Matteo; Repetto, Ernestina

2008-04-01

Among Gram negative bacteria, Pseudomonas aeruginosa, the extended spectrum beta-lactamases (ESBL)-producing strains, Acinetobacter spp, in particular the multiresistant Acinetobacter baumannii, and Stenotrophomonas maltophilia are the most implicated micrororganisms in the ever more increasing problem of bacterial resistance. Possible solutions have to be searched, on one hand, in the use of new drugs but, on the other hand, in the re-evaluation of those already available drugs, possibly considering a new role for old drugs such as colistine and fosfomycin. Concerning ESBL-producing strains, the most recent data provided by EARSS report, in Italy, an incidence rate of 10-25 percent. The insurgence of an infection sustained by an ESBL+ve strain is strictly related to some well known risk factors, like the hospital stay itself, the disease severity, the length of stay in ICU, intubation and mechanical ventilation, catheterization, urinary or artery, and the past exposure to antibiotics. The raise in ESBL producing strains is closely related to the increasing use of cephalosporins. In the setting of a Gram negative infection, the combination therapy guarantees a higher coverage by reducing insurgence of possible resistance mechanisms, possibly resulting synergistic, and allowing a de-escalation therapy, although to this latter other problems, such as tolerability, costs and compliance, can be related. Another basic aspect to take into account of, in order to achieve the maximal efficacy of the antibiotic treatment, is the right dosage. In the idea to look for the best approach for the antibiotic treatment of a severe infection in a hospital setting, when a Gram negative aetiology is implicated, it can be possibly presumed that the right way consists in avoiding inappropriate antibiotic therapies, making therapeutic choices based on guidelines resulted from local epidemiological data, initiating the therapy promptly, avoiding excessive use of antibiotics, possibly

Bacteremias in liver transplant recipients: shift toward gram-negative bacteria as predominant pathogens.

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Singh, Nina; Wagener, Marilyn M; Obman, Asia; Cacciarelli, Thomas V; de Vera, Michael E; Gayowski, Timothy

2004-07-01

During the 1990s, gram-positive bacteria emerged as major pathogens after liver transplantation. We sought to determine whether the pathogens associated with bacteremias in liver transplant recipients have changed. Patients included 233 liver transplant recipients transplanted between 1989 and 2003. The proportion of all infections due to bacteremias increased significantly over time (P gram-negatives increased from 25% in the period of 1989-1993 to 51.8% in 1998-03, that of gram-positive bacteria decreased from 75% in the period of 1989-93 to 48.2% in the period of 1998-2003. Methicillin-resistant Staphylococcus aureus (MRSA), Klebsiella pneumoniae, and Pseudomonas aeruginosa were the most frequent pathogens in bacteremic patients. The incidence of bacteremias due to MRSA and Pseudomonas aeruginosa has remained unchanged (P gram-negative bacteria, particularly Klebsiella pneumoniae has increased (P =.02). Klebsiella pneumoniae isolates in the current quartile were not clonally related. In conclusion, bacteremias as a proportion of all infections in liver transplant recipients have increased significantly over time, due in part to a decline in infections due to other major pathogens, e.g., fungi, primarily Candida species, and CMV. Gram-negative bacteria have emerged as predominant pathogens in bacteremic liver transplant recipients.

CRC DEPLETION CALCULATIONS FOR THE NON-RODDED ASSEMBLIES IN BATCHES 4 AND 5 OF CRYSTAL RIVER UNIT 3

International Nuclear Information System (INIS)

Wright, Kenneth D.

1997-01-01

The purpose of this design analysis is to document the SAS2H depletion calculations of certain non-rodded fuel assemblies from batches 4 and 5 of the Crystal River Unit 3 pressurized water reactor (PWR) that are required for commercial Reactor Critical (CRC) evaluations to support the development of the disposal criticality methodology. A non-rodded assembly is one which never contains a control rod assembly (CRA) or an axial power shaping rod assembly (APSRA) during its irradiation history. The objective of this analysis is to provide SAS2H generated isotopic compositions for each fuel assembly's depleted fuel and depleted burnable poison materials. These SAS2H generated isotopic compositions are acceptable for use in CRC benchmark reactivity calculations containing the various fuel assemblies

Physico-Chemical-Managed Killing of Penicillin-Resistant Static and Growing Gram-Positive and Gram-Negative Vegetative Bacteria

Science.gov (United States)

Richmond, Robert Chaffee (Inventor); Schramm, Jr., Harry F. (Inventor); Defalco, Francis G. (Inventor); Farris, III, Alex F. (Inventor)

2012-01-01

Systems and methods for the use of compounds from the Hofmeister series coupled with specific pH and temperature to provide rapid physico-chemical-managed killing of penicillin-resistant static and growing Gram-positive and Gram-negative vegetative bacteria. The systems and methods represent the more general physico-chemical enhancement of susceptibility for a wide range of pathological macromolecular targets to clinical management by establishing the reactivity of those targets to topically applied drugs or anti-toxins.

In vitro Efficacy of Meropenem, Colistin and Tigecycline Against the Extended Spectrum Beta-Lactamase Producing Gram Negative Bacilli

International Nuclear Information System (INIS)

Gill, M. M.; Usman, J.; Hassan, A.; Kaleem, F.; Anjum, R.

2015-01-01

Objective:To compare the in vitroefficacy of meropenem, colistin and tigecycline against extended spectrum Betalactamase producing Gram negative bacilli by minimal inhibitory concentration. Study Design:Cross-sectional descriptive study. Place and Duration of Study: Department of Microbiology, Army Medical College, National University of Sciences and Technology, Rawalpindi, from June to December 2010. Methodology: Routine clinical specimens were subjected to standard microbiological procedures and the isolates were identified to species level. Extended spectrum beta-lactamase producing Gram negative bacilli were detected by Jarlier disc synergy method and confirmed by ceftazidime and ceftazidime-clavulanate Etest. Minimum Inhibitory Concentration (MIC90) of meropenem, colistin and tigecycline was determined by Etest (AB BIOMERIUX) and the results were interpreted according to the manufacturer's instructions and Clinical and Laboratory Standards Institute guidelines and Food and Drug Authority recommendations. Results were analyzed by using Statistical Package for the Social Sciences version 20. Results: A total of 52 non-duplicate extended spectrum Beta-lactamase-producing Gram negative bacilli were included in the study. The MIC90 of tigecycline (0.75 micro g/ml) was lowest as compared to the meropenem (2 micro g/ml) and colistin (3 micro g/ml). Conclusion: Tigecycline is superior in efficacy against the extended spectrum Beta-lactamase producing Gram negative bacilli as compared to colistin and meropenem. (author)

Emerging Gram negative resistance to last-line antimicrobial agents fosfomycin, colistin and ceftazidime-avibactam - epidemiology, laboratory detection and treatment implications.

Science.gov (United States)

Sherry, Norelle; Howden, Benjamin

2018-04-01

Multidrug-resistant (MDR) and extensively-drug-resistant (XDR) Gram-negative bacteria have emerged as a major threat to human health globally. This has resulted in the 're-discovery' of some older antimicrobials and development of new agents, however resistance has also rapidly emerged to these agents. Areas covered: Here we describe recent developments in resistance to three of the most important last-line antimicrobials for treatment of MDR and XDR Gram negatives: fosfomycin, colistin and ceftazidime-avibactam. Expert commentary: A key challenge for microbiologists and clinicians using these agents for treating patients with MDR and XDR Gram negative infections is the need to ensure appropriate reference methods are being used to test susceptibility to these agents, especially colistin and fosfomycin. These methods are not available in all laboratories meaning accurate results are either delayed, or potentially inaccurate as non-reference methods are employed. Combination therapy for MDR and XDR Gram negatives is likely to become more common, and future studies should focus on the clinical effects of monotherapy vs combination therapy, as well as validation of synergy testing methods. Effective national and international surveillance systems to detect and respond to resistance to these last line agents are also critical.

Prediction of lipoprotein signal peptides in Gram-negative bacteria

DEFF Research Database (Denmark)

Juncker, Agnieszka; Willenbrock, Hanni; Von Heijne, G.

2003-01-01

A method to predict lipoprotein signal peptides in Gram-negative Eubacteria, LipoP, has been developed. The hidden Markov model (HMM) was able to distinguish between lipoproteins (SPaseII-cleaved proteins), SPaseI-cleaved proteins, cytoplasmic proteins, and transmembrane proteins. This predictor ...

Multidrug resistance in enteric and other gram-negative bacteria.

Science.gov (United States)

George, A M

1996-05-15

In Gram-negative bacteria, multidrug resistance is a term that is used to describe mechanisms of resistance by chromosomal genes that are activated by induction or mutation caused by the stress of exposure to antibiotics in natural and clinical environments. Unlike plasmid-borne resistance genes, there is no alteration or degradation of drugs or need for genetic transfer. Exposure to a single drug leads to cross-resistance to many other structurally and functionally unrelated drugs. The only mechanism identified for multidrug resistance in bacteria is drug efflux by membrane transporters, even though many of these transporters remain to be identified. The enteric bacteria exhibit mostly complex multidrug resistance systems which are often regulated by operons or regulons. The purpose of this review is to survey molecular mechanisms of multidrug resistance in enteric and other Gram-negative bacteria, and to speculate on the origins and natural physiological functions of the genes involved.

Fermentative degradation of polyethylene glycol by a strictly anaerobic, gram-negative, nonsporeforming bacterium, Pelobacter venetianus sp. nov.

Science.gov (United States)

Schink, B; Stieb, M

1983-06-01

The synthetic polyether polyethylene glycol (PEG) with a molecular weight of 20,000 was anaerobically degraded in enrichment cultures inoculated with mud of limnic and marine origins. Three strains (Gra PEG 1, Gra PEG 2, and Ko PEG 2) of rod-shaped, gram-negative, nonsporeforming, strictly anaerobic bacteria were isolated in mineral medium with PEG as the sole source of carbon and energy. All strains degraded dimers, oligomers, and polymers of PEG up to a molecular weight of 20,000 completely by fermentation to nearly equal amounts of acetate and ethanol. The monomer ethylene glycol was not degraded. An ethylene glycol-fermenting anaerobe (strain Gra EG 12) isolated from the same enrichments was identified as Acetobacterium woodii. The PEG-fermenting strains did not excrete extracellular depolymerizing enzymes and were inhibited by ethylene glycol, probably owing to a blocking of the cellular uptake system. PEG, some PEG-containing nonionic detergents, 1,2-propanediol, 1,2-butanediol, glycerol, and acetoin were the only growth substrates utilized of a broad variety of sugars, organic acids, and alcohols. The isolates did not reduce sulfate, sulfur, thiosulfate, or nitrate and were independent of growth factors. In coculture with A. woodii or Methanospirillum hungatei, PEGs and ethanol were completely fermented to acetate (and methane). A marine isolate is described as the type strain of a new species, Pelobacter venetianus sp. nov. Its physiology and ecological significance, as well as the importance and possible mechanism of anaerobic polyether degradation, are discussed.

Biodegradation of crude oil in different types of marine sediment

International Nuclear Information System (INIS)

Hii, Y.S.; Law, A.T.

1999-01-01

An active oil-oxidizing bacterium, named Nap C was isolated from the sediment sample of Port Dickson coastal area for this study. Nap C is a gram negative, rod shape marine bacterium. It forms spore when the condition is not favorable. Three different types of treated marine sediment; sand, silt and clay were used in this study. The degradation of Malaysian Tapis A crude oil in the different types of marine sediment were assessed. Silt type of marine sediment was found to sustain highest biodegradation compared to clay type and sand type. 8.6.67% of the Malaysian Tapis A crude oil was degraded in silt type of marine sediment within 10 days of incubation. Where as there were only 60% and 73% of the Malaysian Tapis A crude oil was degraded in sand and clay type of marine sediment respectively. Microbial biomass estimation in the sediment was estimated by indirect phospholipid enumeration technique. (author)

Pollen and spores of terrestrial plants

Science.gov (United States)

Bernhardt, Christopher E.; Willard, Debra A.; Shennan, Ian; Long, Antony J.; Horton, Benjamin P.

2015-01-01

Pollen and spores are valuable tools in reconstructing past sea level and climate because of their ubiquity, abundance, and durability as well as their reciprocity with source vegetation to environmental change (Cronin, 1999; Traverse, 2007; Willard and Bernhardt, 2011). Pollan is found in many sedimentary environments, from freshwater to saltwater, terrestrial to marine. It can be abundant in a minimal amount of sample material, for example half a gram, as concentrations can be as high as four million grains per gram (Traverse, 2007). The abundance of pollen in a sample lends it to robust statistical analysis for the quantitative reconstruction of environments. The outer cell wall is resistant to decay in sediments and allows palynomorphs (pollen and spores) to record changes in plant communities and sea level over millions of years. These characteristics make pollen and spores a powerful tool to use in sea-level research.This chapter describes the biology of pollen and spores and how they are transported and preserved in sediments. We present a methodology for isolating pollen from sediments and a general language and framework to identify pollen as well as light micrographs of a selection of common pollen grains, We then discuss their utility in sea-level research.

False-Negative Rate of Gram-Stain Microscopy for Diagnosis of Septic Arthritis: Suggestions for Improvement

Directory of Open Access Journals (Sweden)

Paul Stirling

2014-01-01

Full Text Available We quantify the false-negative diagnostic rate of septic arthritis using Gram-stain microscopy of synovial fluid and compare this to values reported in the peer-reviewed literature. We propose a method of improving the diagnostic value of Gram-stain microscopy using Lithium Heparin containers that prevent synovial fluid coagulation. Retrospective study of the Manchester Royal Infirmary microbiology database of patients undergoing synovial fluid Gram-stain and culture between December 2003 and March 2012 was undertaken. The initial cohort of 1896 synovial fluid analyses for suspected septic arthritis was reduced to 143 after exclusion criteria were applied. Analysis of our Gram-stain microscopy yielded 111 false-negative results from a cohort size of 143 positive synovial fluid cultures, giving a false-negative rate of 78%. We report a false-negative rate of Gram-stain microscopy for septic arthritis of 78%. Clinicians should therefore avoid the investigation until a statistically significant data set confirms its efficacy. The investigation's value could be improved by using Lithium Heparin containers to collect homogenous synovial fluid samples. Ongoing research aims to establish how much this could reduce the false-negative rate.

Gram-negative and -positive bacteria differentiation in blood culture samples by headspace volatile compound analysis.

Science.gov (United States)

Dolch, Michael E; Janitza, Silke; Boulesteix, Anne-Laure; Graßmann-Lichtenauer, Carola; Praun, Siegfried; Denzer, Wolfgang; Schelling, Gustav; Schubert, Sören

2016-12-01

Identification of microorganisms in positive blood cultures still relies on standard techniques such as Gram staining followed by culturing with definite microorganism identification. Alternatively, matrix-assisted laser desorption/ionization time-of-flight mass spectrometry or the analysis of headspace volatile compound (VC) composition produced by cultures can help to differentiate between microorganisms under experimental conditions. This study assessed the efficacy of volatile compound based microorganism differentiation into Gram-negatives and -positives in unselected positive blood culture samples from patients. Headspace gas samples of positive blood culture samples were transferred to sterilized, sealed, and evacuated 20 ml glass vials and stored at -30 °C until batch analysis. Headspace gas VC content analysis was carried out via an auto sampler connected to an ion-molecule reaction mass spectrometer (IMR-MS). Measurements covered a mass range from 16 to 135 u including CO2, H2, N2, and O2. Prediction rules for microorganism identification based on VC composition were derived using a training data set and evaluated using a validation data set within a random split validation procedure. One-hundred-fifty-two aerobic samples growing 27 Gram-negatives, 106 Gram-positives, and 19 fungi and 130 anaerobic samples growing 37 Gram-negatives, 91 Gram-positives, and two fungi were analysed. In anaerobic samples, ten discriminators were identified by the random forest method allowing for bacteria differentiation into Gram-negative and -positive (error rate: 16.7 % in validation data set). For aerobic samples the error rate was not better than random. In anaerobic blood culture samples of patients IMR-MS based headspace VC composition analysis facilitates bacteria differentiation into Gram-negative and -positive.

Pre-sterilization contamination of disposable medical products and the choice of minimum sterilization dose

International Nuclear Information System (INIS)

Horakova, V.; Buriankova, E.

1975-01-01

The bacterial contamination was assessed on randomly taken samples of blood-transfusion devices, donor sets, intra-uterine contraceptive devices and inserters, surgical gloves and dressing material prior to sterilization. The quantitative and qualitative efficiency of six nutrient media was compared. The best results were obtained with the enriched ''Universal'' medium. It was confirmed that the contamination of plastic products was low compared with dressing material. Most frequently, Gram-positive aerobic spore-forming rods and Gram-positive cocci were found on non-sterile medical disposable products. A method was tested to obtain a general informative picture of the resistance of bacteria on products. The methods used for choosing the dose for radiation sterilization of medical products are discussed. (author)

Antimicrobial Activities of Leaf Extracts of Guava (Psidium guajava L.) on Two Gram-Negative and Gram-Positive Bacteria

Science.gov (United States)

Biswas, Bipul; Rogers, Kimberly; McLaughlin, Fredrick; Yadav, Anand

2013-01-01

Aim. To determine the antimicrobial potential of guava (Psidium guajava) leaf extracts against two gram-negative bacteria (Escherichia coli and Salmonella enteritidis) and two gram-positive bacteria (Staphylococcus aureus and Bacillus cereus) which are some of foodborne and spoilage bacteria. The guava leaves were extracted in four different solvents of increasing polarities (hexane, methanol, ethanol, and water). The efficacy of these extracts was tested against those bacteria through a well-diffusion method employing 50 μL leaf-extract solution per well. According to the findings of the antibacterial assay, the methanol and ethanol extracts of the guava leaves showed inhibitory activity against gram-positive bacteria, whereas the gram-negative bacteria were resistant to all the solvent extracts. The methanol extract had an antibacterial activity with mean zones of inhibition of 8.27 and 12.3 mm, and the ethanol extract had a mean zone of inhibition of 6.11 and 11.0 mm against B. cereus and S. aureus, respectively. On the basis of the present finding, guava leaf-extract might be a good candidate in the search for a natural antimicrobial agent. This study provides scientific understanding to further determine the antimicrobial values and investigate other pharmacological properties. PMID:24223039

Antimicrobial Activities of Leaf Extracts of Guava (Psidium guajava L. on Two Gram-Negative and Gram-Positive Bacteria

Directory of Open Access Journals (Sweden)

Bipul Biswas

2013-01-01

Full Text Available Aim. To determine the antimicrobial potential of guava (Psidium guajava leaf extracts against two gram-negative bacteria (Escherichia coli and Salmonella enteritidis and two gram-positive bacteria (Staphylococcus aureus and Bacillus cereus which are some of foodborne and spoilage bacteria. The guava leaves were extracted in four different solvents of increasing polarities (hexane, methanol, ethanol, and water. The efficacy of these extracts was tested against those bacteria through a well-diffusion method employing 50 μL leaf-extract solution per well. According to the findings of the antibacterial assay, the methanol and ethanol extracts of the guava leaves showed inhibitory activity against gram-positive bacteria, whereas the gram-negative bacteria were resistant to all the solvent extracts. The methanol extract had an antibacterial activity with mean zones of inhibition of 8.27 and 12.3 mm, and the ethanol extract had a mean zone of inhibition of 6.11 and 11.0 mm against B. cereus and S. aureus, respectively. On the basis of the present finding, guava leaf-extract might be a good candidate in the search for a natural antimicrobial agent. This study provides scientific understanding to further determine the antimicrobial values and investigate other pharmacological properties.

Aquimarina hainanensis sp. nov., isolated from diseased Pacific white shrimp Litopenaeus vannamei larvae.

Science.gov (United States)

Zheng, Yanfen; Wang, Yanan; Liu, Yan; Li, Wentao; Yu, Mingchao; Zhang, Xiao-Hua

2016-01-01

One novel Gram-stain-negative, long rod-shaped, non-spore-forming, non-motile, non-flagellated and strictly aerobic strain, designated M124T, was isolated from diseased Pacific white shrimp Litopenaeus vannamei larvae. Growth occurred at 16-37 °C (optimum 28 °C), in the presence of 2-5 % (w/v) NaCl (optimum 3 %) and at pH 7-8 (optimum pH 7). Phylogenetic analysis based on 16S rRNA gene sequences indicated that strain M124T belonged to the genus Aquimarina and showed highest sequence similarity to Aquimarina penaei P3-1T (96.4 %). The dominant fatty acids of the isolate were iso-C15 : 0 and iso-C17 : 0 3-OH. The major polar lipids comprised phosphatidylethanolamine, one unknown aminolipid, three unknown phospholipids, two unknown glycolipids and one unknown polar lipid. The major respiratory quinone was menaquinone 6 (MK-6). The DNA G+C content of strain M124T was 33.7 mol%. Based on the polyphasic analyses in this study, strain M124T is considered to represent a novel species of the genus Aquimarina, for which the name Aquimarina hainanensis sp. nov. is proposed. The type strain is M124T ( = KCTC 42423T = MCCC 1K00498T).

Genome sequence of the dark pink pigmented Listia bainesii microsymbiont Methylobacterium sp. WSM2598.

Science.gov (United States)

Ardley, Julie; Tian, Rui; Howieson, John; Yates, Ron; Bräu, Lambert; Han, James; Lobos, Elizabeth; Huntemann, Marcel; Chen, Amy; Mavromatis, Konstantinos; Markowitz, Victor; Ivanova, Natalia; Pati, Amrita; Goodwin, Lynne; Woyke, Tanja; Kyrpides, Nikos; Reeve, Wayne

2014-01-01

Strains of a pink-pigmented Methylobacterium sp. are effective nitrogen- (N2) fixing microsymbionts of species of the African crotalarioid genus Listia. Strain WSM2598 is an aerobic, motile, Gram-negative, non-spore-forming rod isolated in 2002 from a Listia bainesii root nodule collected at Estcourt Research Station in South Africa. Here we describe the features of Methylobacterium sp. WSM2598, together with information and annotation of a high-quality draft genome sequence. The 7,669,765 bp draft genome is arranged in 5 scaffolds of 83 contigs, contains 7,236 protein-coding genes and 18 RNA-only encoding genes. This rhizobial genome is one of 100 sequenced as part of the DOE Joint Genome Institute 2010 G enomic E ncyclopedia for B acteria and A rchaea- R oot N odule B acteria (GEBA-RNB) project.

CRC DEPLETION CALCULATIONS FOR THE NON-RODDED ASSEMBLIES IN BATCHES 4 AND 5 OF CRYSTAL RIVER UNIT 3

Energy Technology Data Exchange (ETDEWEB)

Kenneth D. Wright

1997-07-30

The purpose of this design analysis is to document the SAS2H depletion calculations of certain non-rodded fuel assemblies from batches 4 and 5 of the Crystal River Unit 3 pressurized water reactor (PWR) that are required for commercial Reactor Critical (CRC) evaluations to support the development of the disposal criticality methodology. A non-rodded assembly is one which never contains a control rod assembly (CRA) or an axial power shaping rod assembly (APSRA) during its irradiation history. The objective of this analysis is to provide SAS2H generated isotopic compositions for each fuel assembly's depleted fuel and depleted burnable poison materials. These SAS2H generated isotopic compositions are acceptable for use in CRC benchmark reactivity calculations containing the various fuel assemblies.

Dual beta-lactam therapy for serious Gram-negative infections: is it time to revisit?

Science.gov (United States)

Rahme, Christine; Butterfield, Jill M; Nicasio, Anthony M; Lodise, Thomas P

2014-12-01

We are rapidly approaching a crisis in antibiotic resistance, particularly among Gram-negative pathogens. This, coupled with the slow development of novel antimicrobial agents, underscores the exigency of redeploying existing antimicrobial agents in innovative ways. One therapeutic approach that was heavily studied in the 1980s but abandoned over time is dual beta-lactam therapy. This article reviews the evidence for combination beta-lactam therapy. Overall, in vitro, animal and clinical data are positive and suggest that beta-lactam combinations produce a synergistic effect against Gram-negative pathogens that rivals that of beta-lactam-aminoglycoside or beta-lactam-fluoroquinolone combination therapy. Although the precise mechanism of improved activity is not completely understood, it is likely attributable to an enhanced affinity to the diverse penicillin-binding proteins found among Gram negatives. The collective data indicate that dual beta-lactam therapy should be revisited for serious Gram-negative infections, especially in light of the near availability of potent beta-lactamase inhibitors, which neutralize the effect of problematic beta-lactamases. Copyright © 2014 Elsevier Inc. All rights reserved.

Characterization of Emericella nidulans RodA and DewA hydrophobin mutants

DEFF Research Database (Denmark)

Jensen, Britt Guillaume; Nielsen, Jakob Blæsbjerg; Pedersen, Mona Højgaard

hydrophobins RodA and DewA. Individual knock-out mutants rodAΔ, dewAΔ and the double deletion strain rodAΔdewAΔ were constructed. Furthermore, two strains containing a point mutation in the first of the cysteines of RodA (rodA-C57G), where one was coupled to the dewA deletion, were included. The reference...... strain (NID1) and dewAΔ displayed green conidia. However, rodAΔ and rodAΔdewAΔ showed a dark green/brown conidial pigmentation, while rodA-C57G and rodAC57G dewAΔ displayed lighter brown conidia. rodAΔ and rodAΔdewAΔ displayed a higher degree of hülle cells compared to the moderate amount observed...... for NID1 and dewAΔ, while rodA-C57G and rodA-C57G dewAΔ displayed a low number of hülle cells. NID1 and dewAΔ conidia were dispersed as spore chains. rodAΔ, rodAΔdewAΔ, rodA-C57G and rodA-C57G dewAΔ spores were associated in large clumps, where the conidia seemed to adhere to one another. The largest...

Phaeobacter piscinae sp. nov., a species of the Roseobacter group and potential aquaculture probiont

DEFF Research Database (Denmark)

Sonnenschein, Eva Christina; Phippen, Christopher Broughton William; Nielsen, Kristian Fog

2017-01-01

pathogenic bacteria. Cells of the strains were Gram-reaction-negative, rod-shaped and formed star-shaped aggregates in liquid culture and brown-coloured colonies on marine agar. The predominant cellular fatty acids were C18 : 1ω7c, C16 : 0, C11 methyl C18 : 1ω7c and C16 : 0 2-OH, and the polar lipids...

Bovine mastitis caused by gram negative bacteria in Mosul

Directory of Open Access Journals (Sweden)

S. Y. A. Al-Dabbagh

2012-01-01

Full Text Available A total of 90 milk samples were collected from cows with clinical and subclinical mastitis from different areas in Mosul city, in a period from October 2009 to June 2010, for the detection of gram negative bacteriological causative agents. The bacteria were identified using morphological, cultural and biochemical characteristics. thirty tow (35.3% gram negative bacterial isolates were obtained from the total count which included 14 isolates (15.5% for Escherichia coli, 7 isolates (7.7% for Klebsiella spp, 4 isolates (4.4% for Pseudomonas aeruginosa, 3 isolates (3.3% for Enterobacter aerogenes ,2 isolates for Serratia marcescens and one isolates (1.1% for each of Aeromonas hydrophila and Pasteurella multocida. Results of antibiotic sensitivity test indicated that most of these isolates were sensitive to Ciprofloxacin following by Gentamycin and Cotrimoxazole, while most of these organisms were resistant to Ampicillin, the isolates showed different percentages of sensitivity to Doxycycline, Tetracycline, Neomycin and Chloramphenicol.

The use of Gram stain and matrix-assisted laser desorption ionization time-of-flight mass spectrometry on positive blood culture: synergy between new and old technology.

Science.gov (United States)

Fuglsang-Damgaard, David; Nielsen, Camilla Houlberg; Mandrup, Elisabeth; Fuursted, Kurt

2011-10-01

Matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF-MS) is promising as an alternative to more costly and cumbersome methods for direct identifications in blood cultures. We wanted to evaluate a simplified pre-treatment method for using MALDI-TOF-MS directly on positive blood cultures using BacT/Alert blood culture system, and to test an algorithm combining the result of the initial microscopy with the result suggested by MALDI-TOF-MS. Using the recommended cut-off score of 1.7 the best results were obtained among Gram-negative rods with correct identifications in 91% of Enterobacteriaceae, 83% in aerobic/non-fermentative Gram-negative rods, whereas results were more modest among Gram-positive cocci with correct identifications in 52% of Staphylococci, 54% in Enterococci and only 20% in Streptococci. Combining the results of Gram stain with the top reports by MALDI-TOF-MS, increased the sensitivity from 91% to 93% in the score range from 1.5 to 1.7 and from 48% to 85% in the score range from 1.3 to 1.5. Thus, using this strategy and accepting a cut-off at 1.3 instead of the suggested 1.7, overall sensitivity could be increased from 88.1% to 96.3%. MALDI-TOF-MS is an efficient method for direct routine identification of bacterial isolates in blood culture, especially when combined with the result of the Gram stain. © 2011 The Authors. APMIS © 2011 APMIS.

CRC DEPLETION CALCULATIONS FOR THE NON-RODDED ASSEMBLIES IN BATCHES 1, 2, AND 3 OF CRYSTAL RIVER UNIT 3

International Nuclear Information System (INIS)

Wright, Kenneth D.

1997-01-01

The purpose of this design analysis is to document the SAS2H depletion calculations of certain non-rodded fuel assemblies from batches 1, 2, and 3 of the Crystal River Unit 3 pressurized water reactor (PWR) that are required for Commercial Reactor Critical (CRC) evaluations to support development of the disposal criticality methodology. A non-rodded assembly is one which never contains a control rod assembly (CRA) or an axial power shaping rod assembly (APSRA) during its irradiation history. The objective of this analysis is to provide SAS2H generated isotopic compositions for each fuel assembly's depleted fuel and depleted burnable poison materials. These SAS2H generated isotopic compositions are acceptable for use in CRC benchmark reactivity calculations containing the various fuel assemblies

Nonlinear tension-bending deformation of a shape memory alloy rod

International Nuclear Information System (INIS)

Shang, Zejin; Wang, Zhongmin

2012-01-01

Based on the measured shape memory alloy (SMA) stress–strain curve and the nonlinear large deformation theory of extensible beams (or rods), the first-order nonlinear governing equations of a SMA cantilever straight rod are established. They consist of a boundary-value problem of ordinary differential equations with a strong nonlinearity, in which seven unknown functions are contained and the arc length of the deformed axis is considered as one of the basic unknown functions. The shooting method combining with the Newton–Raphson iteration method is applied to solve the equations numerically. For a SMA cantilever rod subjected to a transverse uniformly distributed force, the deformation characteristics curves, the maximum strain and the maximum stress distribution curves along the longitudinal direction of rod, and the relation curves between deformation characteristic parameters and transverse uniformly force under different slenderness ratios are obtained. The effects of material nonlinearity, geometrical nonlinearity and slenderness ratio on the tension-bending deformation of the SMA cantilever rod are investigated. The numerical simulation results are in good agreement with the experimental data from the literature, verifying the soundness of the entire numerical simulation scheme. (paper)

Multi-location gram-positive and gram-negative bacterial protein subcellular localization using gene ontology and multi-label classifier ensemble.

Science.gov (United States)

Wang, Xiao; Zhang, Jun; Li, Guo-Zheng

2015-01-01

It has become a very important and full of challenge task to predict bacterial protein subcellular locations using computational methods. Although there exist a lot of prediction methods for bacterial proteins, the majority of these methods can only deal with single-location proteins. But unfortunately many multi-location proteins are located in the bacterial cells. Moreover, multi-location proteins have special biological functions capable of helping the development of new drugs. So it is necessary to develop new computational methods for accurately predicting subcellular locations of multi-location bacterial proteins. In this article, two efficient multi-label predictors, Gpos-ECC-mPLoc and Gneg-ECC-mPLoc, are developed to predict the subcellular locations of multi-label gram-positive and gram-negative bacterial proteins respectively. The two multi-label predictors construct the GO vectors by using the GO terms of homologous proteins of query proteins and then adopt a powerful multi-label ensemble classifier to make the final multi-label prediction. The two multi-label predictors have the following advantages: (1) they improve the prediction performance of multi-label proteins by taking the correlations among different labels into account; (2) they ensemble multiple CC classifiers and further generate better prediction results by ensemble learning; and (3) they construct the GO vectors by using the frequency of occurrences of GO terms in the typical homologous set instead of using 0/1 values. Experimental results show that Gpos-ECC-mPLoc and Gneg-ECC-mPLoc can efficiently predict the subcellular locations of multi-label gram-positive and gram-negative bacterial proteins respectively. Gpos-ECC-mPLoc and Gneg-ECC-mPLoc can efficiently improve prediction accuracy of subcellular localization of multi-location gram-positive and gram-negative bacterial proteins respectively. The online web servers for Gpos-ECC-mPLoc and Gneg-ECC-mPLoc predictors are freely accessible

[Characteristic of clinical strains of gram-negative obligate anaerobes].

Science.gov (United States)

Kadzielska, Joanna; Kierzkowska, Marta; Sawicka-Grzelak, Anna; Rokosz, Alicja; Łuczak, Mirosław

2007-01-01

The aim of the study was to assess prevalence and antibiotic susceptibility profiles ofGram-negative strictly anaerobic bacteria isolated from clinical specimens taken from hospitalized patients in 2005-2006. Biochemical identification and antibiotic susceptibility were done in an automated system ATB Expression (bioMerieux sa). From 12262 specimens examined 867 strains of obligate anaerobes were isolated. Gram-negative strictly anaerobic bacteria were cultured in number of 138 strains (15,9%). All cultures were performed on Columbia agar and Schaedler agar media (bioMerieux sa) supplemented with 5% sheep blood and incubated at 37 degrees C for 48-120 h in 85% N2, 10% H2, 5% CO2. Most frequently isolated was Bacteroides spp. (41,3%). For this group beta-lactamase activity was evaluated by using nitrocefin disc test (Cefinase BBL, Becton Dickinson and Co., Cockeysville, MD, USA). Production of ESBLs was detected with the use of two disc diffusion methods: the double-disc synergy test (DDST) according to Jarlier et al. and the diagnostic disc (DD) test according to Appleton. ESBLs were produced by 5,3% strains of Bacteroides spp. For all Bacteroides spp. strains MIC values were determined by gradient diffusion method Etest (AB BIODISK, Sweden). ESBLs and MIC were performed on Wilkins-Chalgren solid medium supplemented with 5% sheep blood (Difco Lab., USA) and all plates were incubated at 35 degrees C for 48 hours in 85% N2, 10% H2, 5% CO2. Most Gram-negative obligate anaerobes isolated from clinical specimens are still susceptible to imipenem (100%), metronidazole (99,3%) and beta-lactam antibiotics with beta-lactamase inhibitors: piperacillin/tazobactam (99,3%), ticarcillin/clavulanate (99.3%), amoxicillin/clavulanate (97.8%).

Survival and detection of coliforms, Enterobacteriaceae, and gram-negative bacteria in Greek yogurt.

Science.gov (United States)

Hervert, C J; Martin, N H; Boor, K J; Wiedmann, M

2017-02-01

Despite the widespread use of coliforms as indicator bacteria, increasing evidence suggests that the Enterobacteriaceae (EB) and total gram-negative groups more accurately reflect the hygienic status of high-temperature, short-time pasteurized milk and processing environments. If introduced into milk as postpasteurization contamination, these bacteria may grow to high levels and produce a wide range of sensory-related defects. However, limited information is available on the use and survival of bacterial hygiene indicators in dairy products outside of pasteurized fluid milk and cheese. The goal of this study was to (1) provide information on the survival of a diverse set of bacterial hygiene indicators in the low pH environment of Greek yogurt, (2) compare traditional and alternative detection methods for their ability to detect bacterial hygiene indicators in Greek yogurt, and (3) offer insight into optimal hygiene indicator groups for use in low-pH fermented dairy products. To this end, we screened 64 bacterial isolates, representing 24 dairy-relevant genera, for survival and detection in Greek yogurt using 5 testing methods. Before testing, isolates were inoculated into plain, 0% fat Greek yogurt (pH 4.35 to 4.65), followed by a 12-h hold period at 4 ± 1°C. Yogurts were subsequently tested using Coliform Petrifilm (3M, St. Paul, MN) to detect coliforms; Enterobacteriaceae Petrifilm (3M), violet red bile glucose agar and the D-Count (bioMérieux, Marcy-l'Étoile, France) to detect EB; and crystal violet tetrazolium agar (CVTA) to detect total gram-negative bacteria. Overall, the non-EB gram-negative isolates showed significantly larger log reductions 12 h after inoculation into Greek yogurt (based on bacterial numbers recovered on CVTA) compared with the coliform and noncoliform EB isolates tested. The methods evaluated varied in their ability to detect different microbial hygiene indicators in Greek yogurt. Crystal violet tetrazolium agar detected the highest

Thermotoga lettingae sp. nov. : a novel thermophilic, methanol-degrading bacterium isolated from a thermophilic anaerobic reactor

NARCIS (Netherlands)

Balk, M.; Weijma, J.; Stams, A.J.M.

2002-01-01

A novel, anaerobic, non-spore-forming, mobile, Gram-negative, thermophilic bacterium, strain TMO(T), was isolated from a thermophilic sulfate-reducing bioreactor operated at 65 degrees C with methanol as the sole substrate. The G C content of the DNA of strain TMO(T) was 39.2 molÐThe optimum pH,

Rapid, highly sensitive detection of Gram-negative bacteria with lipopolysaccharide based disposable aptasensor.

Science.gov (United States)

Zhang, Jian; Oueslati, Rania; Cheng, Cheng; Zhao, Ling; Chen, Jiangang; Almeida, Raul; Wu, Jayne

2018-07-30

Gram-negative bacteria are one of the most common microorganisms in the environment. Their differential detection and recognition from Gram-positive bacteria has been attracting much attention over the years. Using Escherichia coli (E. coli) as a model, we demonstrated on-site detection of Gram-negative bacteria by an AC electrokinetics-based capacitive sensing method using commercial microelectrodes functionalized with an aptamer specific to lipopolysaccharides. Dielectrophoresis effect was utilized to enrich viable bacteria to the microelectrodes rapidly, achieving a detection limit of 10 2 cells/mL within a 30 s' response time. The sensor showed a negligible response to Staphylococcus aureus (S. aureus), a Gram-positive species. The developed sensor showed significant advantages in sensitivity, selectivity, cost, operation simplicity, and response time. Therefore, this sensing method has shown great application potential for environmental monitoring, food safety, and real-time diagnosis. Copyright © 2018 Elsevier B.V. All rights reserved.

A pathway closely related to the (D)-tagatose pathway of gram-negative enterobacteria identified in the gram-positive bacterium Bacillus licheniformis.

Science.gov (United States)

Van der Heiden, Edwige; Delmarcelle, Michaël; Lebrun, Sarah; Freichels, Régine; Brans, Alain; Vastenavond, Christian M; Galleni, Moreno; Joris, Bernard

2013-06-01

We report the first identification of a gene cluster involved in d-tagatose catabolism in Bacillus licheniformis. The pathway is closely related to the d-tagatose pathway of the Gram-negative bacterium Klebsiella oxytoca, in contrast to the d-tagatose 6-phosphate pathway described in the Gram-positive bacterium Staphylococcus aureus.

A Pathway Closely Related to the d-Tagatose Pathway of Gram-Negative Enterobacteria Identified in the Gram-Positive Bacterium Bacillus licheniformis

OpenAIRE

Van der Heiden, Edwige; Delmarcelle, Michaël; Lebrun, Sarah; Freichels, Régine; Brans, Alain; Vastenavond, Christian M.; Galleni, Moreno; Joris, Bernard

2013-01-01

We report the first identification of a gene cluster involved in d-tagatose catabolism in Bacillus licheniformis. The pathway is closely related to the d-tagatose pathway of the Gram-negative bacterium Klebsiella oxytoca, in contrast to the d-tagatose 6-phosphate pathway described in the Gram-positive bacterium Staphylococcus aureus.

Automated Interpretation of Blood Culture Gram Stains by Use of a Deep Convolutional Neural Network.

Science.gov (United States)

Smith, Kenneth P; Kang, Anthony D; Kirby, James E

2018-03-01

Microscopic interpretation of stained smears is one of the most operator-dependent and time-intensive activities in the clinical microbiology laboratory. Here, we investigated application of an automated image acquisition and convolutional neural network (CNN)-based approach for automated Gram stain classification. Using an automated microscopy platform, uncoverslipped slides were scanned with a 40× dry objective, generating images of sufficient resolution for interpretation. We collected 25,488 images from positive blood culture Gram stains prepared during routine clinical workup. These images were used to generate 100,213 crops containing Gram-positive cocci in clusters, Gram-positive cocci in chains/pairs, Gram-negative rods, or background (no cells). These categories were targeted for proof-of-concept development as they are associated with the majority of bloodstream infections. Our CNN model achieved a classification accuracy of 94.9% on a test set of image crops. Receiver operating characteristic (ROC) curve analysis indicated a robust ability to differentiate between categories with an area under the curve of >0.98 for each. After training and validation, we applied the classification algorithm to new images collected from 189 whole slides without human intervention. Sensitivity and specificity were 98.4% and 75.0% for Gram-positive cocci in chains and pairs, 93.2% and 97.2% for Gram-positive cocci in clusters, and 96.3% and 98.1% for Gram-negative rods. Taken together, our data support a proof of concept for a fully automated classification methodology for blood-culture Gram stains. Importantly, the algorithm was highly adept at identifying image crops with organisms and could be used to present prescreened, classified crops to technologists to accelerate smear review. This concept could potentially be extended to all Gram stain interpretive activities in the clinical laboratory. Copyright © 2018 American Society for Microbiology.

Associations Between Enteral Colonization With Gram-Negative Bacteria and Intensive Care Unit-Acquired Infections and Colonization of the Respiratory Tract.

Science.gov (United States)

Frencken, Jos F; Wittekamp, Bastiaan H J; Plantinga, Nienke L; Spitoni, Cristian; van de Groep, Kirsten; Cremer, Olaf L; Bonten, Marc J M

2018-02-01

Enteral and respiratory tract colonization with gram-negative bacteria may lead to subsequent infections in critically ill patients. We aimed to clarify the interdependence between gut and respiratory tract colonization and their associations with intensive care unit (ICU)-acquired infections in patients receiving selective digestive tract decontamination (SDD). Colonization status of the rectum and respiratory tract was determined using twice-weekly microbiological surveillance in mechanically ventilated subjects receiving SDD between May 2011 and June 2015 in a tertiary medical-surgical ICU in the Netherlands. Acquisition of infections was monitored daily by dedicated observers. Marginal structural models were used to determine the associations between gram-negative rectal colonization and respiratory tract colonization, ICU-acquired gram-negative infection, and ICU-acquired gram-negative bacteremia. Among 2066 ICU admissions, 1157 (56.0%) ever had documented gram-negative carriage in the rectum during ICU stay. Cumulative incidences of ICU-acquired gram-negative infection and bacteremia were 6.0% (n = 124) and 2.1% (n = 44), respectively. Rectal colonization was an independent risk factor for both respiratory tract colonization (cause-specific hazard ratio [CSHR], 2.93 [95% confidence interval {CI}, 2.02-4.23]) and new gram-negative infection in the ICU (CSHR, 3.04 [95% CI, 1.99-4.65]). Both rectal and respiratory tract colonization were associated with bacteremia (CSHR, 7.37 [95% CI, 3.25-16.68] and 2.56 [95% CI, 1.09-6.03], respectively). Similar associations were observed when Enterobacteriaceae and glucose nonfermenting gram-negative bacteria were analyzed separately. Gram-negative rectal colonization tends to be stronger associated with subsequent ICU-acquired gram-negative infections than gram-negative respiratory tract colonization. Gram-negative rectal colonization seems hardly associated with subsequent ICU-acquired gram-negative respiratory tract

Molecular analysis of sourdough reveals Lactobacillus mindensis sp. nov.

Science.gov (United States)

Ehrmann, Matthias A; Müller, Martin R A; Vogel, Rudi F

2003-01-01

Genotypic fingerprinting to analyse the bacterial flora of an industrial sourdough revealed a coherent group of strains which could not be associated with a valid species. Comparative 16S rDNA sequence analysis showed that these strains formed a homogeneous cluster distinct from their closest relatives, Lactobacillus farciminis, Lactobacillus alimentarius and Lactobacillus kimchii. To characterize them further, physiological (sugar fermentation, formation of DL-lactate, hydrolysis of arginine, growth temperature, CO2 production) and chemotaxonomic properties have been determined. The DNA G +C content was 37.5 0.2 mol%. The peptidoglycan was of the lysine-D-iso-asparagine (L-Lys-D-Asp) type. The strains were homofermentative, Gram-positive, catalase-negative, non-spore-forming, non-motile rods. They were found as a major stable component of a rye flour sourdough fermentation. Physiological, biochemical as well as genotypic data suggested them to be a new species of the genus Lactobacillus. This was confirmed by DNA-DNA hybridization of genomic DNA, and the name Lactobacillus mindensis is proposed. The type strain of this species is DSM 14500T (=LMG 21508T).

Thermophysical instruments for non-destructive examination of tightness and internal gas pressure or irradiated power reactor fuel rods

International Nuclear Information System (INIS)

Pastoushin, V.V.; Novikov, A.Yu.; Bibilashvili, Yu.K.

1998-01-01

The developed thermophysical method and technical instruments for non-destructive leak-tightness and gas pressure inspection inside irradiated power reactor fuel rods and FAs under poolside and hot cell conditions are described. The method of gas pressure measuring based on the examination of parameters of thermal convection that aroused in gas volume of rod plenum by special technical instruments. The developed method and technique allows accurate value determination of not only one of the main critical rod parameters, namely total internal gas pressure, that forms rod mean life in the reactor core, but also the partial pressure of every main constituent of gaseous mixture inside irradiated fuel rod, that provides the feasibility of authentic and reliable leak-tightness detection. The described techniques were experimentally checked during the examination of all types power reactor fuel rods existing in Russia (WWER, BN, RBMK) and could form the basis for new technique development for non-destructive examination of PWR (and other) type rods and FAs having gas plenum filled with spring or another elements of design. (author)

Massilia phosphatilytica sp. nov., a phosphate solubilizing bacteria isolated from a long-term fertilized soil

DEFF Research Database (Denmark)

Zheng, Bang Xiao; Bi, Qing Fang; Hao, Xiuli

2017-01-01

A Gram-stain-negative and rod-shaped bacterial strain, 12-OD1T, with rock phosphate solubilizing ability was isolated from agricultural soil in Hailun, Heilongjiang, PR China. The isolate was affiliated to the genus Massilia, based on 16S rRNA gene sequence alignments, having the highest similari......A Gram-stain-negative and rod-shaped bacterial strain, 12-OD1T, with rock phosphate solubilizing ability was isolated from agricultural soil in Hailun, Heilongjiang, PR China. The isolate was affiliated to the genus Massilia, based on 16S rRNA gene sequence alignments, having the highest...

A Pathway Closely Related to the d-Tagatose Pathway of Gram-Negative Enterobacteria Identified in the Gram-Positive Bacterium Bacillus licheniformis

Science.gov (United States)

Van der Heiden, Edwige; Lebrun, Sarah; Freichels, Régine; Brans, Alain; Vastenavond, Christian M.; Galleni, Moreno; Joris, Bernard

2013-01-01

We report the first identification of a gene cluster involved in d-tagatose catabolism in Bacillus licheniformis. The pathway is closely related to the d-tagatose pathway of the Gram-negative bacterium Klebsiella oxytoca, in contrast to the d-tagatose 6-phosphate pathway described in the Gram-positive bacterium Staphylococcus aureus. PMID:23524682

Insights into the optical and anti-bacterial properties of biogenic PbSe quantum rods

Directory of Open Access Journals (Sweden)

Jaya Mary Jacob

2016-07-01

Full Text Available The detailed optical properties of lead selenide (PbSe quantum rods biosynthesized in marine Aspergillus terreus were apprehended theoretically using ab initio calculations based on the experimental absorption spectrum. These studies indicate that the absorption coefficient of the biosynthesized PbSe quantum rods increases linearly with incident photon energies. The variation of other optical constants like extinction coefficient, refractive index and reflectance was comparable to that of the chemically synthesized counterparts. Further, the high dielectric constant and remarkable fluorescence of the biogenic PbSe quantum rods pronounce their application in opto-electronic devices in the Near Infra-Red and Ultraviolet spectral regime. The biosynthesized PbSe quantum rods were also found to possess appreciable anti-bacterial activity against various gram positive and gram negative bacterial species thus enhancing the relevance of the same for practical utility. Based on these results it can be concluded that biogenic PbSe quantum rods can be envisaged as potential candidates for bio-imaging, bio-sensing and other photo-voltaic applications.

Identification of a Novel Lipoprotein Regulator of Clostridium difficile Spore Germination.

Directory of Open Access Journals (Sweden)

Kelly A Fimlaid

2015-10-01

Full Text Available Clostridium difficile is a Gram-positive spore-forming pathogen and a leading cause of nosocomial diarrhea. C. difficile infections are transmitted when ingested spores germinate in the gastrointestinal tract and transform into vegetative cells. Germination begins when the germinant receptor CspC detects bile salts in the gut. CspC is a subtilisin-like serine pseudoprotease that activates the related CspB serine protease through an unknown mechanism. Activated CspB cleaves the pro-SleC zymogen, which allows the activated SleC cortex hydrolase to degrade the protective cortex layer. While these regulators are essential for C. difficile spores to outgrow and form toxin-secreting vegetative cells, the mechanisms controlling their function have only been partially characterized. In this study, we identify the lipoprotein GerS as a novel regulator of C. difficile spore germination using targeted mutagenesis. A gerS mutant has a severe germination defect and fails to degrade cortex even though it processes SleC at wildtype levels. Using complementation analyses, we demonstrate that GerS secretion, but not lipidation, is necessary for GerS to activate SleC. Importantly, loss of GerS attenuates the virulence of C. difficile in a hamster model of infection. Since GerS appears to be conserved exclusively in related Peptostreptococcaeace family members, our results contribute to a growing body of work indicating that C. difficile has evolved distinct mechanisms for controlling the exit from dormancy relative to B. subtilis and other spore-forming organisms.

Bioemulsan Production by Iranian Oil Reservoirs Microorganisms

Directory of Open Access Journals (Sweden)

A Amiriyan, M Mazaheri Assadi, VA Saggadian, A Noohi

2004-10-01

Full Text Available The biosurfactants are believed to be surface active components that are shed into the surrounding medium during the growth of the microorganisms. The oil degrading microorganism Acinetobacter calcoaceticus RAG-1 produces a poly-anionic biosurfactant, hetero-polysaccharide bioemulsifier termed as emulsan which forms and stabilizes oil-water emulsions with a variety of hydrophobic substrates. In the present paper results of the possibility of biosurfactant (Emulsan production by microorganisms isolated from Iranian oil reservoirs is presented. Fourthy three gram negative and gram positive, non fermentative, rod bacilli and coccobacilli shaped baceria were isolated from the oil wells of Bibi Hakimeh, Siri, Maroon, Ilam , East Paydar and West Paydar. Out of the isolated strains, 39 bacterial strains showed beta haemolytic activity, further screening revealed the emulsifying activity and surface tension. 11 out of 43 tested emulsifiers were identified as possible biosurfactant producers and two isolates produced large surface tension reduction, indicating the high probability of biosurfactant production. Further investigation revealed that, two gram negative, oxidase negative, aerobic and coccoid rods isolates were the best producers and hence designated as IL-1, PAY-4. Whole culture broth of isolates reduced surface tension from 68 mN /m to 30 and 29.1mN/m, respectively, and were stable during exposure to high salinity (10%NaCl and elevated temperatures(120C for 15 min .

Induction of gram-negative bacterial growth by neurochemical containing banana (Musa x paradisiaca) extracts.

Science.gov (United States)

Lyte, M

1997-09-15

Bananas contain large quantities of neurochemicals. Extracts from the peel and pulp of bananas in increasing stages of ripening were prepared and evaluated for their ability to modulate the growth of non-pathogenic and pathogenic bacteria. Extracts from the peel, and to a much lesser degree the pulp, increased the growth of Gram-negative bacterial strains Escherichia coli O157:H7, Shigella flexneri, Enterobacter cloacae and Salmonella typhimurium, as well as two non-pathogenic E. coli strains, in direct relation to the content of norepinephrine and dopamine, but not serotonin. The growth of Gram-positive bacteria was not altered by any of the extracts. Supplementation of vehicle and pulp cultures with norepinephrine or dopamine yielded growth equivalent to peel cultures. Total organic analysis of extracts further demonstrated that the differential effects of peel and pulp on bacterial growth was not nutritionally based, but due to norepinephrine and dopamine. These results suggest that neurochemicals contained within foodstuffs may influence the growth of pathogenic and indigenous bacteria through direct neurochemical-bacterial interactions.

Non-susceptibility trends among Pseudomonas aeruginosa and other non-fermentative Gram-negative bacteria from bacteraemias in the UK and Ireland, 2001-06.

Science.gov (United States)

Livermore, David M; Hope, Russell; Brick, Geraldine; Lillie, Mark; Reynolds, Rosy

2008-11-01

Pseudomonas and Acinetobacter spp. are important opportunists, notorious for resistance. Pseudomonas spp. are collected in the British Society for Antimicrobial Chemotherapy (BSAC) bacteraemia surveillance, with Acinetobacter spp. and Stenotrophomonas maltophilia well represented in the 'other Gram-negatives' group. Data for collected isolates were reviewed together with LabBase bacteraemia reports to the Health Protection Agency (HPA). Isolates with unusual resistances were subjected to molecular investigation. From 2001 to 2006, the BSAC surveillance collected 1226 Pseudomonas aeruginosa, 240 Acinetobacter spp.-125 of them Acinetobacter calcoaceticus/baumannii (Acb) complex-and 165 S. maltophilia. Among P. aeruginosa, non-susceptibility rates to beta-lactams and gentamicin fluctuated, without trend, below 10%; those to ciprofloxacin ranged from 16% to 22%. One P. aeruginosa isolate from 2001 had VIM-2 metallo-beta-lactamase. For Acb, the BSAC data indicated frequent non-susceptibility, except to imipenem, where only five non-susceptible isolates were collected, all after 2003, four of them belonging to the OXA-23 clone 1 lineage which is prevalent in Southeast England. Reports to the HPA indicated rising imipenem non-susceptibility in Acb (P /=16 mg/L for Acb OXA-23 clone 1. Ceftobiprole had higher MICs than ceftazidime for P. aeruginosa, but 81% of the isolates were inhibited at non-susceptibility emerging.

Curative Treatment of Severe Gram-Negative Bacterial Infections by a New Class of Antibiotics Targeting LpxC.

Science.gov (United States)

Lemaître, Nadine; Liang, Xiaofei; Najeeb, Javaria; Lee, Chul-Jin; Titecat, Marie; Leteurtre, Emmanuelle; Simonet, Michel; Toone, Eric J; Zhou, Pei; Sebbane, Florent

2017-07-25

The infectious diseases caused by multidrug-resistant bacteria pose serious threats to humankind. It has been suggested that an antibiotic targeting LpxC of the lipid A biosynthetic pathway in Gram-negative bacteria is a promising strategy for curing Gram-negative bacterial infections. However, experimental proof of this concept is lacking. Here, we describe our discovery and characterization of a biphenylacetylene-based inhibitor of LpxC, an essential enzyme in the biosynthesis of the lipid A component of the outer membrane of Gram-negative bacteria. The compound LPC-069 has no known adverse effects in mice and is effective in vitro against a broad panel of Gram-negative clinical isolates, including several multiresistant and extremely drug-resistant strains involved in nosocomial infections. Furthermore, LPC-069 is curative in a murine model of one of the most severe human diseases, bubonic plague, which is caused by the Gram-negative bacterium Yersinia pestis Our results demonstrate the safety and efficacy of LpxC inhibitors as a new class of antibiotic against fatal infections caused by extremely virulent pathogens. The present findings also highlight the potential of LpxC inhibitors for clinical development as therapeutics for infections caused by multidrug-resistant bacteria. IMPORTANCE The rapid spread of antimicrobial resistance among Gram-negative bacilli highlights the urgent need for new antibiotics. Here, we describe a new class of antibiotics lacking cross-resistance with conventional antibiotics. The compounds inhibit LpxC, a key enzyme in the lipid A biosynthetic pathway in Gram-negative bacteria, and are active in vitro against a broad panel of clinical isolates of Gram-negative bacilli involved in nosocomial and community infections. The present study also constitutes the first demonstration of the curative treatment of bubonic plague by a novel, broad-spectrum antibiotic targeting LpxC. Hence, the data highlight the therapeutic potential of Lpx

Curative Treatment of Severe Gram-Negative Bacterial Infections by a New Class of Antibiotics Targeting LpxC

Energy Technology Data Exchange (ETDEWEB)

Lemaître, Nadine; Liang, Xiaofei; Najeeb, Javaria; Lee, Chul-Jin; Titecat, Marie; Leteurtre, Emmanuelle; Simonet, Michel; Toone, Eric J.; Zhou, Pei; Sebbane, Florent; Nacy, Carol A.

2017-07-25

The infectious diseases caused by multidrug-resistant bacteria pose serious threats to humankind. It has been suggested that an antibiotic targeting LpxC of the lipid A biosynthetic pathway in Gram-negative bacteria is a promising strategy for curing Gram-negative bacterial infections. However, experimental proof of this concept is lacking. Here, we describe our discovery and characterization of a biphenylacetylene-based inhibitor of LpxC, an essential enzyme in the biosynthesis of the lipid A component of the outer membrane of Gram-negative bacteria. The compound LPC-069 has no known adverse effects in mice and is effectivein vitroagainst a broad panel of Gram-negative clinical isolates, including several multiresistant and extremely drug-resistant strains involved in nosocomial infections. Furthermore, LPC-069 is curative in a murine model of one of the most severe human diseases, bubonic plague, which is caused by the Gram-negative bacteriumYersinia pestis. Our results demonstrate the safety and efficacy of LpxC inhibitors as a new class of antibiotic against fatal infections caused by extremely virulent pathogens. The present findings also highlight the potential of LpxC inhibitors for clinical development as therapeutics for infections caused by multidrug-resistant bacteria.

IMPORTANCEThe rapid spread of antimicrobial resistance among Gram-negative bacilli highlights the urgent need for new antibiotics. Here, we describe a new class of antibiotics lacking cross-resistance with conventional antibiotics. The compounds inhibit LpxC, a key enzyme in the lipid A biosynthetic pathway in Gram-negative bacteria, and are activein vitroagainst a broad panel of clinical isolates of Gram-negative bacilli involved in nosocomial and community infections. The present study also constitutes the first demonstration of the curative treatment of bubonic plague by a novel, broad

Evaluation of the limulus amoebocyte lysate test in conjunction with a gram negative bacterial plate count for detecting irradiation of chicken

Science.gov (United States)

Scotter, Susan L.; Wood, Roger; McWeeny, David J.

A study to evaluate the potential of the Limulus amoebocyte lysate (LAL) test in conjuction with a Gram negative bacteria (GNB) plate count for detecting the irradiation of chicken is described. Preliminary studies demonstrated that chickens irradiated at an absorbed dose of 2.5 kGy could be differentiated from unirradiated birds by measuring levels of endotoxin and of numbers of GNB on chicken skin. Irradiated birds were found to have endotoxin levels similar to those found in unirradiated birds but significantly lower numbers of GNB. In a limited study the test was found to be applicable to birds from different processors. The effect of temperature abuse on the microbiological profile, and thus the efficacy of the test, was also investigated. After temperature abuse, the irradiated birds were identifiable at worst up to 3 days after irradiation treatment at the 2.5 kGy level and at best some 13 days after irradiation. Temperature abuse at 15°C resulted in rapid recovery of surviving micro-organisms which made differentiation of irradiated and unirradiated birds using this test unreliable. The microbiological quality of the bird prior to irradiation treatment also affected the test as large numbers of GNB present on the bird prior to irradiation treatment resulted in larger numbers of survivors. In addition, monitoring the developing flora after irradiation treatment and during subsequent chilled storage also aided differentiation of irradiated and unirradiated birds. Large numbers of yeasts and Gram positive cocci were isolated from irradiated carcasses whereas Gram negative oxidative rods were the predominant spoilage flora on unirradiated birds.

Evaluation of the Limulus amoebocyte lysate test in conjunction with a gram negative bacterial plate count for detecting irradiation of chicken

International Nuclear Information System (INIS)

Scotter, S.L.; Wood, R.; McWeeny, D.J.

1990-01-01

A study to evaluate the potential of the Limulus amoebocyte lysate (LAL) test in conjunction with a Gram negative bacterial (GNB) plate count for detecting the irradiation of chicken is described. Preliminary studies demonstrated that chickens irradiated at an absorbed dose of 2.5 kGy could be differentiated from unirradiated birds by measuring levels of endotoxin and of numbers of GNB on chicken skin. Irradiated birds were found to have endotoxin levels similar to those found in unirradiated birds but significantly lower numbers of GNB. In a limited study the test was found to be applicable to birds from different processors. The effect of temperature abuse on the microbiological profile, and thus the efficacy of the test, was also investigated. After temperature abuse, the irradiated birds were identifiable at worst up to 3 days after irradiation treatment at the 2.5 kGy level and at best some 13 days after irradiation. Temperature abuse at 15 0 C resulted in rapid recovery of surviving micro-organisms which made differentiation of irradiated and unirradiated birds using this test unreliable. The microbiological quality of the bird prior to irradiation treatment also affected the test as large numbers of GNB present on the bird prior to irradiation treatment resulted in larger numbers of survivors. In addition, monitoring the developing flora after irradiation treatment amd during subsequent chilled storage also aided differentiation of irradiated and unirradiated birds. Large numbers of yeast and Gram positive cocci were isolated from irradiated carcasses whereas Gram negative oxidative rods were the predominant spoilage flora on unirradiated birds. (author)

Evaluation of the Limulus amoebocyte lysate test in conjunction with a gram negative bacterial plate count for detecting irradiation of chicken

Energy Technology Data Exchange (ETDEWEB)

Scotter, S L; Wood, R; McWeeny, D J [Ministry of Agriculture, Fisheries and Food, Norwich (UK). Food Science Lab.

1990-01-01

A study to evaluate the potential of the Limulus amoebocyte lysate (LAL) test in conjunction with a Gram negative bacterial (GNB) plate count for detecting the irradiation of chicken is described. Preliminary studies demonstrated that chickens irradiated at an absorbed dose of 2.5 kGy could be differentiated from unirradiated birds by measuring levels of endotoxin and of numbers of GNB on chicken skin. Irradiated birds were found to have endotoxin levels similar to those found in unirradiated birds but significantly lower numbers of GNB. In a limited study the test was found to be applicable to birds from different processors. The effect of temperature abuse on the microbiological profile, and thus the efficacy of the test, was also investigated. After temperature abuse, the irradiated birds were identifiable at worst up to 3 days after irradiation treatment at the 2.5 kGy level and at best some 13 days after irradiation. Temperature abuse at 15{sup 0}C resulted in rapid recovery of surviving micro-organisms which made differentiation of irradiated and unirradiated birds using this test unreliable. The microbiological quality of the bird prior to irradiation treatment also affected the test as large numbers of GNB present on the bird prior to irradiation treatment resulted in larger numbers of survivors. In addition, monitoring the developing flora after irradiation treatment amd during subsequent chilled storage also aided differentiation of irradiated and unirradiated birds. Large numbers of yeast and Gram positive cocci were isolated from irradiated carcasses whereas Gram negative oxidative rods were the predominant spoilage flora on unirradiated birds. (author).

Thermaerobacter litoralis sp. nov., a strictly aerobic and thermophilic bacterium isolated from a coastal hydrothermal field

DEFF Research Database (Denmark)

Tanaka, Reiji; Kawaichi, Satoshi; Nishimura, Hiroshi

2006-01-01

A novel thermophilic bacterium, strain KW1T, was isolated from a coastal hydrothermal field on the Satsuma Peninsula, Kagoshima Prefecture, Japan. The variably Gram-stained cells were motile rods with flagella, did not form spores and proliferated at 52-78°C (optimum, 70°C), pH 5-8 (optimum, pH 7...

Rhabdobacter roseus gen. nov., sp. nov., isolated from soil.

Science.gov (United States)

Dahal, Ram Hari; Kim, Jaisoo

2016-01-01

An aerobic, Gram-stain-negative, oxidase- and catalase-positive, non-motile, non-spore-forming, rod-shaped, pink-pigmented bacterium, designated strain R49T, was isolated from soil. Flexirubin-type pigments were absent. Phylogenetic analysis based on its 16S rRNA gene sequence revealed that strain R49T formed a lineage within the family Cytophagaceae of the phylum Bacteroidetes that was distinct from the most closely related genera Dyadobacter (91.98-93.85 % sequence similarity), Persicitalea (88.69 %) and Runella (84.79-85.81 %). The major isoprenoid quinone was menaquinone-7 (MK-7) and the major polar lipid was phosphatidylethanolamine. The major cellular fatty acids were summed feature 3 (C16 : 1ω7c and/or C16 : 1ω6c), iso-C15 : 0, C16 : 1ω5c, C16 : 0 and iso-C17 : 0 3-OH. The DNA G+C content of strain R49T was 53.9 mol%. On the basis of phenotypic, genotypic and phylogenetic analysis, strain R49T represents a novel species of a new genus in the family Cytophagaceae, for which the name Rhabdobacter roseus gen. nov., sp. nov. is proposed. The type strain of Rhabdobacter roseus is R49T ( = KEMB 9005-318T = KACC 18395T = JCM 30685T).

Repulsion between oppositely charged rod-shaped macromolecules: Role of overcharging and ionic confinement

Science.gov (United States)

Antila, Hanne S.; Van Tassel, Paul R.; Sammalkorpi, Maria

2017-09-01

The interaction between two oppositely charged rod-shaped macro-ions in a micro-ion solution is investigated via Monte Carlo simulations of the primitive model. The focus is on the asymmetry in rod and/or ion charge, i.e., conditions where oppositely charged objects can repel one another. For equally and oppositely charged rods with asymmetric z:1 micro-ions, repulsion may be induced by overcharging one of the rods with the z valent ions. For asymmetrically charged rods in a symmetric z:z micro-ion solution, a repulsive interaction—at separation of the order of one ion diameter—can arise via an unbalanced osmotic pressure contribution from the ionic atmosphere in the inter-rod space, and an attractive interaction—at a smaller separation—may occur due to a "squeezing out" of the micro-ions from the space between the rods (with a consequent gain in entropy). The thermodynamics of each mechanism is investigated in terms of rod charge and size and micro-ion valence, size, and concentration. Our findings contribute to the understanding of the complex role of charge asymmetry on the interaction of, for example, oppositely charged polyelectrolytes, functionalized nanotubes, and rod-like biomolecules, e.g., viruses.

Development and transmission of antimicrobial resistance among Gram-negative bacteria in animals and their public health impact.

Science.gov (United States)

Mukerji, Shewli; O'Dea, Mark; Barton, Mary; Kirkwood, Roy; Lee, Terence; Abraham, Sam

2017-02-28

Gram-negative bacteria are known to cause severe infections in both humans and animals. Antimicrobial resistance (AMR) in Gram-negative bacteria is a major challenge in the treatment of clinical infections globally due to the propensity of these organisms to rapidly develop resistance against antimicrobials in use. In addition, Gram-negative bacteria possess highly efficient mechanisms through which the AMR can be disseminated between pathogenic and commensal bacteria of the same or different species. These unique traits of Gram-negative bacteria have resulted in evolution of Gram-negative bacterial strains demonstrating resistance to multiple classes of antimicrobials. The evergrowing resistance issue has not only resulted in limitation of treatment options but also led to increased treatment costs and mortality rates in humans and animals. With few or no new antimicrobials in production to combat severe life-threatening infections, AMR has been described as the one of the most severe, long-term threats to human health. Aside from overuse and misuse of antimicrobials in humans, another factor that has exacerbated the emergence of AMR in Gram-negative bacteria is the veterinary use of antimicrobials that belong to the same classes considered to be critically important for treating serious life-threatening infections in humans. Despite the fact that development of AMR dates back to before the introduction of antimicrobials, the recent surge in the resistance towards all available critically important antimicrobials has emerged as a major public health issue. This review thus focuses on discussing the development, transmission and public health impact of AMR in Gram-negative bacteria in animals. © 2017 The Author(s). Published by Portland Press Limited on behalf of the Biochemical Society.

Acaricomes phytoseiuli gen. nov., sp. nov., isolated from the predatory mite Phytoseiulus persimilis.

Science.gov (United States)

Pukall, Rüdiger; Schumann, Peter; Schütte, Conny; Gols, Rieta; Dicke, Marcel

2006-02-01

A Gram-positive, rod-shaped, non-spore-forming bacterium, strain CSCT, was isolated from diseased, surface-sterilized specimens of the predatory mite Phytoseiulus persimilis Athias-Henriot and subjected to polyphasic taxonomic analysis. Comparative analysis of the 16S rRNA gene sequence revealed that the strain was a new member of the family Micrococcaceae. Nearest phylogenetic neighbours were determined as Renibacterium salmoninarum (94.0%), Arthrobacter globiformis (94.8%) and Arthrobacter russicus (94.6%). Although the predominant fatty acids (anteiso C15:0), cell-wall sugars (galactose, glucose) and polar lipids (diphosphatidylglycerol, phosphatidylglycerol, phosphatidylinositol) are in accordance with those of members of the genus Arthrobacter, strain CSCT can be distinguished from members of the genus Arthrobacter by biochemical tests, the absence of a rod-coccus life cycle and the occurrence of the partially saturated menaquinone MK-10(H2) as the predominant menaquinone. The DNA G+C content is 57.7 mol%. On the basis of morphological, chemotaxonomic and phylogenetic differences from other species of the Micrococcaceae, a novel genus and species are proposed, Acaricomes phytoseiuli gen. nov., sp. nov. The type strain is CSCT (=DSM 14247T=CCUG 49701T).

Serratia ureilytica sp. nov., a novel urea-utilizing species.

Science.gov (United States)

Bhadra, Bhaskar; Roy, Pradosh; Chakraborty, Ranadhir

2005-09-01

A Gram-negative, rod-shaped, urea-dissolving and non-spore-forming bacterium, designated strain NiVa 51(T), was isolated from water of the River Torsa in Hasimara, Jalpaiguri district, West Bengal, India. On the basis of 16S rRNA gene sequence similarity, strain NiVa 51(T) was shown to belong to the gamma-Proteobacteria and to be related to Serratia marcescens subsp. sakuensis (98.35%) and S. marcescens subsp. marcescens (98.30%); however, strain NiVa 51(T) exhibited only 43.7% similarity to S. marcescens by DNA-DNA hybridization. The G+C content of the genomic DNA of the isolate was 60 mol%. Both biochemical characteristics and fatty acid analysis data supported the affiliation of strain NiVa 51(T) to the genus Serratia. Furthermore, strain NiVa 51(T) was found to utilize urea as nitrogen source. The results of DNA-DNA hybridization as well as physiological and biochemical tests allowed genotypic and phenotypic differentiation of strain NiVa 51(T) from recognized Serratia species. Strain NiVa 51(T) therefore represents a novel species, for which the name Serratia ureilytica sp. nov. is proposed, with type strain NiVa 51(T) (=LMG 22860(T)=CCUG 50595(T)).

Genotypic and Phylogenic Analysis of Lactobacilli Producing Bacteriocin Isolated from Traditional Dairy Products and Food

Directory of Open Access Journals (Sweden)

Frazaneh Tafvizi

2012-09-01

Full Text Available Background & Objective: Lactic acid bacteria (LAB are a group of Gram-positive, non-spore forming, cocci or rod shaped, catalase negative organisms, considered as Generally Recognized as Safe (GRAS organisms. These bacteria are used for thousands of years for production of fermented foods because of their ability to produce desirable changes in taste, flavor and texture. Different antimicrobial molecules such as bacteriocins produced by these bacteria that can inhibit food pathogens, so enhancing the shelf life and improving the safety of food products. Because of important role of LAB to improving the human health, molecular identification and phylogenic analysis of these bacteria based on 16S rRNA sequencing play the critical role in investigation of local sources of LAB in Iran. Materials & Methods: 5 isolates were selected from 20 isolates for molecular identification. These strains produced the high level of bacteriocin. Total genomic DNA was extracted by lysosyme extraction protocol. PCR-mediated amplification was carried out by degenerate primers. Sequencing was performed after purification of PCR product. Results: Isolates were deposited as novel strains of Lactobacillus casei and Entrococcus facium in GenBank. Conclusion: Because of high potential of local probiotic bacteria in Iran, these strains may be useful and could be used in the food industry.

Microbial extremophiles from the 2008 Schirmacher Oasis Expedition: preliminary results

Science.gov (United States)

Hoover, Richard B.; Pikuta, Elena V.; Townsend, Alisa; Anthony, Joshua; Guisler, Melissa; McDaniel, Jasmine; Bej, Asim; Storrie-Lombardi, Michael

2008-08-01

Among the most interesting targets for Astrobiology research are the polar ice caps and the permafrost of Mars and the ice and liquid water bodies that may lie beneath the frozen crusts of comets, the icy moons of Jupiter (Europa, Io and Ganymede) and Saturn (Titan and Enceladus). The permanently ice-covered lakes of Antarctica, such as Lake Vostok and Lake Untersee, provide some of the best terrestrial analogues for these targets. The 2008 International Tawani Schirmacher Oasis/Lake Untersee Expeditions have been organized to conduct studies of novel microbial extremophiles and investigate the biodiversity of the glaciers and ice-covered lakes of Dronning Maud Land, East Antarctica. This paper describes the preliminary analysis of the anaerobic microbial extremophiles isolated from samples collected during the 2008 International Schirmacher Oasis Antarctica Reconnaissance Expedition. These samples showed great diversity of psychrophlic and psychrotolerant bacteria. Six new anaerobic strains have been isolated in pure cultures and partially characterized. Two of them (strains ARHSd-7G and ARHSd-9G) were isolated from a small tidal pool near the colony of African Penguins Spheniscus demersus. Strain ARHSd-7G was isolated on mineral anaerobic medium with 3 % NaCl, pH 7 and D-glucose, it has motile, vibrion shape cells, and is Gram variable. Strain ARHSd-9G grew on anaerobic, alkaline medium with pH 9 and 1 % NaCl at 3°C. The substrate was D-glucose supplemented with yeast extract (0.05 %). Cells of strain ARHSd-9G had morphology of straight or slightly curved elongated rods and demonstrated unusual optical effects under dark-field visible light microscopy. The cells were spore-forming and Gram positive. From the mat sample collected near Lake Zub, the new strain LZ-3 was isolated in pure culture at 3°C. Strain LZ-3 was anaerobic and grew on 0.5 % NaCl mineral medium with Dglucose as a substrate. The gram positive cells were spore-forming. They exhibited a

Surface-Exposed Lipoproteins: An Emerging Secretion Phenomenon in Gram-Negative Bacteria.

Science.gov (United States)

Wilson, Marlena M; Bernstein, Harris D

2016-03-01

Bacterial lipoproteins are hydrophilic proteins that are anchored to a cell membrane by N-terminally linked fatty acids. It is widely believed that nearly all lipoproteins produced by Gram-negative bacteria are either retained in the inner membrane (IM) or transferred to the inner leaflet of the outer membrane (OM). Lipoproteins that are exposed on the cell surface have also been reported but are generally considered to be rare. Results from a variety of recent studies, however, now suggest that the prevalence of surface-exposed lipoproteins has been underestimated. In this review we describe the evidence that the surface exposure of lipoproteins in Gram-negative bacteria is a widespread phenomenon and discuss possible mechanisms by which these proteins might be transported across the OM. Published by Elsevier Ltd.

In vitro activity of XF-73, a novel antibacterial agent, against antibiotic-sensitive and -resistant Gram-positive and Gram-negative bacterial species.

Science.gov (United States)

Farrell, David J; Robbins, Marion; Rhys-Williams, William; Love, William G

2010-06-01

The antibacterial activity of XF-73, a dicationic porphyrin drug, was investigated against a range of Gram-positive and Gram-negative bacteria with known antibiotic resistance profiles, including resistance to cell wall synthesis, protein synthesis, and DNA and RNA synthesis inhibitors as well as cell membrane-active antibiotics. Antibiotic-sensitive strains for each of the bacterial species tested were also included for comparison purposes. XF-73 was active [minimum inhibitory concentration (MIC) 0.25-4 mg/L] against all of the Gram-positive bacteria tested, irrespective of the antibiotic resistance profile of the isolates, suggesting that the mechanism of action of XF-73 is unique compared with the major antibiotic classes. Gram-negative activity was lower (MIC 1 mg/L to > 64 mg/L). Minimum bactericidal concentration data confirmed that the activity of XF-73 was bactericidal. Time-kill kinetics against healthcare-associated and community-associated meticillin-resistant Staphylococcus aureus isolates demonstrated that XF-73 was rapidly bactericidal, with > 5 log(10) kill obtained after 15 min at 2 x MIC, the earliest time point sampled. The post-antibiotic effect (PAE) for XF-73 under conditions where the PAE for vancomycin was 5.4 h. XF-73 represents a novel broad-spectrum Gram-positive antibacterial drug with potentially beneficial characteristics for the treatment and prevention of Gram-positive bacterial infections. 2010. Published by Elsevier B.V.

Comparative activity of tigecycline and tetracycline on Gram-negative and Gram-positive bacteria revealed by a multicentre study in four North European countries

DEFF Research Database (Denmark)

Nilsson, Lennart E; Frimodt-Møller, Niels; Vaara, Martti

2011-01-01

This study involves a multicentre surveillance of tigecycline and tetracycline activity against Gram-negative and Gram-positive bacteria from primary care centres (PCCs), general hospital wards (GHWs) and intensive care units (ICUs) in Denmark (n = 9), Finland (n = 10), Norway (n = 7) and Sweden (n...

Lactobacillus micheneri sp. nov., Lactobacillus timberlakei sp. nov. and Lactobacillus quenuiae sp. nov., lactic acid bacteria isolated from wild bees and flowers.

Science.gov (United States)

McFrederick, Quinn S; Vuong, Hoang Q; Rothman, Jason A

2018-04-12

Gram-stain-positive, rod-shaped, non-spore forming bacteria have been isolated from flowers and the guts of adult wild bees in the families Megachilidae and Halictidae. Phylogenetic analysis of the 16S rRNA gene indicated that these bacteria belong to the genus Lactobacillus, and are most closely related to the honey-bee associated bacteria Lactobacillus kunkeei (97.0 % sequence similarity) and Lactobacillus apinorum (97.0 % sequence similarity). Phylogenetic analyses of 16S rRNA genes and six single-copy protein coding genes, in situ and in silico DNA-DNA hybridization, and fatty-acid profiling differentiates the newly isolated bacteria as three novel Lactobacillus species: Lactobacillus micheneri sp. nov. with the type strain Hlig3 T (=DSM 104126 T ,=NRRL B-65473 T ), Lactobacillus timberlakei with the type strain HV_12 T (=DSM 104128 T ,=NRRL B-65472 T ), and Lactobacillus quenuiae sp. nov. with the type strain HV_6 T (=DSM 104127 T ,=NRRL B-65474 T ).

Fulminant leukemoid reaction due to postpartum Clostridium sordellii infection

Directory of Open Access Journals (Sweden)

Prabhat Agrawal

2012-01-01

Full Text Available Clostridium sordellii is gram positive anaerobic spore forming rod and it has been demonstrated to cause gas gangrene, refractory shock, leukemoid reaction, and pleuroperitoneal effusion due to capillary leak. We report here a case of postpartum female who presented with leukemoid reaction, ascites, pleural effusion, and shock without fever 7 days after normal vaginal home delivery.

Induction of L-form-like cell shape change of Bacillus subtilis under microculture conditions.

Science.gov (United States)

Shingaki, Ryuji; Kasahara, Yasuhiro; Iwano, Megumi; Kuwano, Masayoshi; Takatsuka, Tomomasa; Inoue, Tetsuyoshi; Kokeguchi, Susumu; Fukui, Kazuhiro

2003-09-01

A remarkable cell shape change was observed in Bacillus subtilis strain 168 under microculture conditions on CI agar medium (Spizizen's minimal medium supplemented with a trace amount of yeast extract and Casamino acids). Cells cultured under a cover glass changed in form from rod-shaped to spherical, large and irregular shapes that closely resembled L-form cells. The cell shape change was observed only with CI medium, not with Spizizen's minimum medium alone or other rich media. The whole-cell protein profile of cells grown under cover glass and cells grown on CI agar plates differed in several respects. Tandem mass analysis of nine gel bands which differed in protein expression between the two conditions showed that proteins related to nitrate respiration and fermentation were expressed in the shape-changed cells grown under cover glass. The cell shape change of CI cultures was repressed when excess KNO3 was added to the medium. Whole-cell protein analysis of the normal rod-shaped cells grown with 0.1% KNO3 and the shape-changed cells grown without KNO3 revealed that the expression of the branched-chain alpha-keto acid dehydrogenase complex (coded by the bfmB gene locus) was elevated in the shape-changed cells. Inactivation of the bfmB locus resulted in the repression of cell shape change, and cells in which bfmB expression was induced by IPTG did show changes in shape. Transmission electron microscopy of ultrathin sections demonstrated that the shape-changed cells had thin walls, and plasmolysis of cells fixed with a solution including 0.1 M sucrose was observed. Clarifying the mechanism of thinning of the cell wall may lead to the development of a new type of cell wall biosynthetic inhibitor.

Mucispirillum schaedleri gen. nov., sp nov., a spiral-shaped bacterium colonizing the mucus layer of the gastrointestinal tract of laboratory rodents

DEFF Research Database (Denmark)

Robertson, B.R.; O'Rourke, J.L.; Neilan, B.A.

2005-01-01

in the domain Bacteria. There was a high level of consensus in results obtained from the phenotypic and genotypic characterization of a number of the isolates, which showed they were distinct from other members of the Deferribacteres. As such, they are proposed to constitute a new genus and species......, Mucispirillum schaedleri gen. nov., sp. nov. These organisms are anaerobic, Gram-negative, spiral-shaped rods with bipolar flagella. The type strain is HRI 117(T) (=ATCC BAA-1009(T) = ACM 5223(T))....

Prevalence of AmpC β-lactamase among Gram-negative bacteria ...

African Journals Online (AJOL)

Purpose: Infections caused by AmpC-positive bacteria results in high patient morbidity and mortality making their detection clinically important as they cannot be detected in routine susceptibility testing. This study aim to determine the prevalence of AmpC β-lactamase among Gram negative bacteria recovered from clinical ...

Mutant prevention concentrations of four carbapenems against gram-negative rods.

Science.gov (United States)

Credito, Kim; Kosowska-Shick, Klaudia; Appelbaum, Peter C

2010-06-01

We tested the propensities of four carbapenems to select for resistant Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa, and Acinetobacter baumannii mutants by determining the mutant prevention concentrations (MPCs) for 100 clinical strains with various ss-lactam phenotypes. Among the members of the Enterobacteriaceae family and A. baumannii strains, the MPC/MIC ratios were mostly 2 to 4. In contrast, for P. aeruginosa the MPC/MIC ratios were 4 to > or =16. The MPC/MIC ratios for beta-lactamase-positive K. pneumoniae and E. coli isolates were much higher (range, 4 to >16 microg/ml) than those for ss-lactamase-negative strains.

Restriction of cephalosporins and control of extended spectrum beta-lactamase producing gram negative bacteria in a neonatal intensive care unit.

Science.gov (United States)

Murki, Srinivas; Jonnala, Sravanthi; Mohammed, Faheemuddin; Reddy, Anupama

2010-09-01

This interventional study with historical controls was conducted to study the effect of cephalosporin restriction on the incidence of extended spectrum beta-lactamase (ESBL) gram negative infections in neonates admitted to intensive care unit. All gram negative isolates from the blood were evaluated for beta lactamase production. The incidence of ESBL production was compared before (year 2007) and after cephalosporin restriction (year 2008). Thirty two neonates (3% of NICU admissions) in the year 2007 and fifty six (5.2%) in the year 2008, had gram negative septicemia. The incidence of ESBL gram negatives decreased by 22% (47% to 25%, P=0.03). Restriction of all class of cephalosporins significantly decreased the incidence of ESBL gram negative infections.

Gram staining.

Science.gov (United States)

Coico, Richard

2005-10-01

Named after Hans Christian Gram who developed the method in 1884, the Gram stain allows one to distinguish between Gram-positive and Gram-negative bacteria on the basis of differential staining with a crystal violet-iodine complex and a safranin counterstain. The cell walls of Gram-positive organisms retain this complex after treatment with alcohol and appear purple, whereas gram-negative organisms decolorize following such treatment and appear pink. The method described here is useful for assessing bacterial contamination of tissue culture samples or for examining the Gram stain status and morphological features of bacteria isolated from mixed or isolated bacterial cultures.

The nature of water within bacterial spores: protecting life in extreme environments

Science.gov (United States)

Rice, Charles V.; Friedline, Anthony; Johnson, Karen; Zachariah, Malcolm M.; Thomas, Kieth J., III

2011-10-01

The bacterial spore is a formidable container of life, protecting the vital contents from chemical attack, antimicrobial agents, heat damage, UV light degradation, and water dehydration. The exact role of the spore components remains in dispute. Nevertheless, water molecules are important in each of these processes. The physical state of water within the bacterial spore has been investigated since the early 1930's. The water is found two states, free or bound, in two different areas, core and non-core. It is established that free water is accessible to diffuse and exchange with deuterated water and that the diffusible water can access all areas of the spore. The presence of bound water has come under recent scrutiny and has been suggested the water within the core is mobile, rather than bound, based on the analysis of deuterium relaxation rates. Using an alternate method, deuterium quadrupole-echo spectroscopy, we are able to distinguish between mobile and immobile water molecules. In the absence of rapid motion, the deuterium spectrum of D2O is dominated by a broad line, whose line shape is used as a characteristic descriptor of molecular motion. The deuterium spectrum of bacterial spores reveals three distinct features: the broad peak of immobilized water, a narrow line of water in rapid motion, and a signal of intermediate width. This third signal is assigned this peak from partially deuterated proteins with the spore in which N-H groups have undergone exchange with water deuterons to form N-D species. As a result of these observations, the nature of water within the spore requires additional explanation to understand how the spore and its water preserve life.

Hydrothermal vents in Lake Tanganyika harbor spore-forming thermophiles with extremely rapid growth

DEFF Research Database (Denmark)

Elsgaard, Lars; Prieur, Daniel

2010-01-01

A thermophilic anaerobic bacterium was isolated from a sublacustrine hydrothermal vent site in Lake Tanganyika (East Africa) with recorded fluid temperatures of 66–103 °C and pH values of 7.7–8.9. The bacterium (strain TR10) was rod-shaped, about 1 by 5 μm in size, and readily formed distal...... and peptone. The optimum temperature for growth was 60 °C, while minimum and maximum temperatures were 40 and 75 °C. The pH response was alkalitolerant with optimum pH at 7.4 and 8.5 depending on the growth medium. The distinct feature of rapid proliferation and endospore formation may allow the novel...

Pricia antarctica gen. nov., sp. nov., a member of the family Flavobacteriaceae, isolated from Antarctic intertidal sediment.

Science.gov (United States)

Yu, Yong; Li, Hui-Rong; Zeng, Yin-Xin; Sun, Kun; Chen, Bo

2012-09-01

A yellow-coloured, rod-shaped, Gram-reaction- and Gram-staining-negative, non-motile and aerobic bacterium, designated strain ZS1-8(T), was isolated from a sample of sandy intertidal sediment collected from the Antarctic coast. Flexirubin-type pigments were absent. In phylogenetic analyses based on 16S rRNA gene sequences, strain ZS1-8(T) formed a distinct phyletic line and the results indicated that the novel strain should be placed in a new genus within the family Flavobacteriaceae. In pairwise comparisons between strain ZS1-8(T) and recognized species, the levels of 16S rRNA gene sequence similarity were all antarctica gen. nov., sp. nov. is proposed. The type strain of the type species is ZS1-8(T) (= JCM 17291(T) = DSM 23421(T)).

Modified two-step emulsion solvent evaporation technique for fabricating biodegradable rod-shaped particles in the submicron size range.

Science.gov (United States)

Safari, Hanieh; Adili, Reheman; Holinstat, Michael; Eniola-Adefeso, Omolola

2018-05-15

Though the emulsion solvent evaporation (ESE) technique has been previously modified to produce rod-shaped particles, it cannot generate small-sized rods for drug delivery applications due to the inherent coupling and contradicting requirements for the formation versus stretching of droplets. The separation of the droplet formation from the stretching step should enable the creation of submicron droplets that are then stretched in the second stage by manipulation of the system viscosity along with the surface-active molecule and oil-phase solvent. A two-step ESE protocol is evaluated where oil droplets are formed at low viscosity followed by a step increase in the aqueous phase viscosity to stretch droplets. Different surface-active molecules and oil phase solvents were evaluated to optimize the yield of biodegradable PLGA rods. Rods were assessed for drug loading via an imaging agent and vascular-targeted delivery application via blood flow adhesion assays. The two-step ESE method generated PLGA rods with major and minor axis down to 3.2 µm and 700 nm, respectively. Chloroform and sodium metaphosphate was the optimal solvent and surface-active molecule, respectively, for submicron rod fabrication. Rods demonstrated faster release of Nile Red compared to spheres and successfully targeted an inflamed endothelium under shear flow in vitro and in vivo. Copyright © 2018 Elsevier Inc. All rights reserved.

NDM 1 Gene Carrying Gram negative Bacteria Isolated from Rats ...

African Journals Online (AJOL)

In this study, we screened 56 Gram negative bacteria comprising: 3 isolates of Enterobacter ludwigii, 30 Pseudomonas aeruginosa, 22 Proteus mirabilis, and 1 Aeromonas caviae isolated from oral cavity and rectum of rats captured from commercial poultry houses in Ibadan, Oyo State, Nigeria that were resistant to at least ...

Bryocella elongata

NARCIS (Netherlands)

Dedysh, S.N.; Kulichevskaya, I.S.; Serkebaeva, Y.M.; Mityaeva, M.A.; Sorokin, V.V.; Suzina, N.E.; Rijpstra, W.I.C.; Sinninghe Damsté, J.S.

2012-01-01

An aerobic, pink-pigmented, chemo-organotrophic bacterium, designated strain SN10(T), was isolated from a methanotrophic enrichment culture obtained from an acidic Sphagnum peat. This isolate was represented by Gram-negative, non-motile rods that multiply by normal cell division and form rosettes.

[i]Legionella spp[/i]., amoebae and not-fermenting Gram negative bacteria in an Italian university hospital water system

Directory of Open Access Journals (Sweden)

Pasqualina Laganà

2014-09-01

Full Text Available [b]Introduction. [/b]In hospital and other health care facilities, contamination of water systems by potentially infectious microorganisms, such as bacteria, viruses and protozoa, is a source of nosocomial infections, which may originate fromcolonization of water pipes, cooling towers, spa pools, taps, showers and water supplies. [b]Objective. [/b]The study focuses on the occurrence of [i]Legionella spp.[/i], free-living amoebae and non-fermenting Gram-negative microorganisms in a University hospital water system located in the town of Messina (Sicily, Italy, which had never been examined previously. Materials and Methods. From January 2008 – March 2009, hot tap water samples were collected from 10 wards.[i] Legionella spp[/i]. recovered on selective culture medium were identified by microagglutination latex test; free-living amoebae were cultured using [i]Escherichia coli [/i]as a food source. Non-fermenting Gram negative microorganisms were identified by API 20 NE strips. [b]Results.[/b] [i]Legionella spp.[/i] were found in 33.33% of the samples. [i]L. pneumophila[/i] serogroup 1 was recovered from the Laboratory Diagnostic and Anaesthesia-Neurology Wards, with a peak of 3.5 × 10[sup]4[/sup] cfu/L in May 2008. [i]L. pneumophila[/i] serogroups 2–14 were found in the Othorhinolaryngology, Pathologic Anatomy, Paediatrics and Surgery Wards, and peaked (4 × 10[sup]4[/sup] cfu/L in April 2008. Pseudomonadaceae and Hyphomycetes were also detected. Legionella spp. were recovered from samples positive for non-pathogenic amoebae [i]Hartmannella spp[/i]. [b]Conclusion.[/b] This first study of a Messina hospital water system suggested potential health risks related to the detection of [i]Hartmannella spp[/i]., as reservoirs for[i] Legionella spp.[/i], and Pseudomonas aeruginosa, a Gram negative non-fermenting bacterium frequently causing nosocomial pneumonia. The urgent need for monitoring programmes and prevention measures to ensure hospital water

Antibacterial properties of biosurfactants against selected Gram-positive and -negative bacteria.

Science.gov (United States)

Díaz De Rienzo, Mayri A; Stevenson, Paul; Marchant, Roger; Banat, Ibrahim M

2016-01-01

The antibacterial properties and ability to disrupt biofilms of biosurfactants (rhamnolipids, sophorolipids) and sodium dodecyl sulphate (SDS) in the presence and absence of selected organic acids were investigated. Pseudomonas aeruginosa PAO1 was inhibited by sophorolipids and SDS at concentrations >5% v/v, and the growth of Escherichia coli NCTC 10418 was also inhibited by sophorolipids and SDS at concentrations >5% and 0.1% v/v, respectively. Bacillus subtilis NCTC 10400 was inhibited by rhamnolipids, sophorolipids and SDS at concentrations >0.5% v/v of all three; the same effect was observed with Staphylococcus aureus ATCC 9144. The ability to attach to surfaces and biofilm formation of P. aeruginosa PAO1, E. coli NCTC 10418 and B. subtilis NCTC 10400 was inhibited by sophorolipids (1% v/v) in the presence of caprylic acid (0.8% v/v). In the case of S. aureus ATCC 9144, the best results were obtained using caprylic acid on its own. It was concluded that sophorolipids are promising compounds for the inhibition/disruption of biofilms formed by Gram-positive and Gram-negative microorganisms and this activity can be enhanced by the presence of booster compounds such as caprylic acid. © FEMS 2015. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

The Growing Threat of Multidrug-Resistant Gram-Negative Infections in Patients with Hematologic Malignancies

Science.gov (United States)

Baker, Thomas M.; Satlin, Michael J.

2016-01-01

Prolonged neutropenia and chemotherapy-induced mucositis render patients with hematologic malignancies highly vulnerable to Gram-negative bacteremia. Unfortunately, multidrug-resistant (MDR) Gram-negative bacteria are increasingly encountered globally, and current guidelines for empirical antibiotic coverage in these patients may not adequately treat these bacteria. This expansion of resistance, coupled with traditional culturing techniques requiring 2-4 days for bacterial identification and antimicrobial susceptibility results, have grave implications for these immunocompromised hosts. This review characterizes the epidemiology, risk factors, resistance mechanisms, recommended treatments, and outcomes of the MDR Gram-negative bacteria that commonly cause infections in patients with hematologic malignancies. We also examine infection prevention strategies in hematology patients, such as infection control practices, antimicrobial stewardship, and targeted decolonization. Finally, we assess strategies to improve outcomes of infected patients, including gastrointestinal screening to guide empirical antibiotic therapy, new rapid diagnostic tools for expeditious identification of MDR pathogens, and use of two new antimicrobial agents, ceftolozane/tazobactam and ceftazidime/avibactam. PMID:27339405

Integrating rapid diagnostics and antimicrobial stewardship improves outcomes in patients with antibiotic-resistant Gram-negative bacteremia.

Science.gov (United States)

Perez, Katherine K; Olsen, Randall J; Musick, William L; Cernoch, Patricia L; Davis, James R; Peterson, Leif E; Musser, James M

2014-09-01

An intervention for Gram-negative bloodstream infections that integrated mass spectrometry technology for rapid diagnosis with antimicrobial stewardship oversight significantly improved patient outcomes and reduced hospital costs. As antibiotic resistance rates continue to grow at an alarming speed, the current study was undertaken to assess the impact of this intervention in a challenging patient population with bloodstream infections caused by antibiotic-resistant Gram-negative bacteria. A total of 153 patients with antibiotic-resistant Gram-negative bacteremia hospitalized prior to the study intervention were compared to 112 patients treated post-implementation. Outcomes assessed included time to optimal antibiotic therapy, time to active treatment when inactive, hospital and intensive care unit length of stay, all-cause 30-day mortality, and total hospital expenditures. Integrating rapid diagnostics with antimicrobial stewardship improved time to optimal antibiotic therapy (80.9 h in the pre-intervention period versus 23.2 h in the intervention period, P Gram-negatives. The intervention decreased hospital and intensive care unit length of stay, total hospital costs, and reduced all-cause 30-day mortality. Copyright © 2014. Published by Elsevier Ltd.

Performance of Gram staining on blood cultures flagged negative by an automated blood culture system.

Science.gov (United States)

Peretz, A; Isakovich, N; Pastukh, N; Koifman, A; Glyatman, T; Brodsky, D

2015-08-01

Blood is one of the most important specimens sent to a microbiology laboratory for culture. Most blood cultures are incubated for 5-7 days, except in cases where there is a suspicion of infection caused by microorganisms that proliferate slowly, or infections expressed by a small number of bacteria in the bloodstream. Therefore, at the end of incubation, misidentification of positive cultures and false-negative results are a real possibility. The aim of this work was to perform a confirmation by Gram staining of the lack of any microorganisms in blood cultures that were identified as negative by the BACTEC™ FX system at the end of incubation. All bottles defined as negative by the BACTEC FX system were Gram-stained using an automatic device and inoculated on solid growth media. In our work, 15 cultures that were defined as negative by the BACTEC FX system at the end of the incubation were found to contain microorganisms when Gram-stained. The main characteristic of most bacteria and fungi growing in the culture bottles that were defined as negative was slow growth. This finding raises a problematic issue concerning the need to perform Gram staining of all blood cultures, which could overload the routine laboratory work, especially laboratories serving large medical centers and receiving a large number of blood cultures.

Growth and Morphology of Rod Eutectics

Energy Technology Data Exchange (ETDEWEB)

Jing Teng; Shan Liu; R. Trivedi

2008-03-17

The formation of rod eutectic microstructure is investigated systematically in a succinonitrile-camphor alloy of eutectic composition by using the directional solidification technique. A new rod eutectic configuration is observed in which the rods form with elliptical cylindrical shape. Two different orientations of the ellipse are observed that differ by a 90{sup o} rotation such that the major and the minor axes are interchanged. Critical experiments in thin samples, where a single layer of rods forms, show that the spacing and orientation of the elliptic rods are governed by the growth rate and the sample thickness. In thicker samples, multi layers of rods form with circular cross-section and the scaling law between the spacing and velocity predicted by the Jackson and Hunt model is validated. A theoretical model is developed for a two-dimensional array of elliptical rods that are arranged in a hexagonal or a square array, and the results are shown to be consistent with the experimental observations. The model of elliptic rods is also shown to reduce to that for the circular rod eutectic when the lengths of the two axes are equal, and to the lamellar eutectic model when one of the axes is much larger than the other one.

Curative Treatment of Severe Gram-Negative Bacterial Infections by a New Class of Antibiotics Targeting LpxC

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Nadine Lemaître

2017-07-01

Full Text Available The infectious diseases caused by multidrug-resistant bacteria pose serious threats to humankind. It has been suggested that an antibiotic targeting LpxC of the lipid A biosynthetic pathway in Gram-negative bacteria is a promising strategy for curing Gram-negative bacterial infections. However, experimental proof of this concept is lacking. Here, we describe our discovery and characterization of a biphenylacetylene-based inhibitor of LpxC, an essential enzyme in the biosynthesis of the lipid A component of the outer membrane of Gram-negative bacteria. The compound LPC-069 has no known adverse effects in mice and is effective in vitro against a broad panel of Gram-negative clinical isolates, including several multiresistant and extremely drug-resistant strains involved in nosocomial infections. Furthermore, LPC-069 is curative in a murine model of one of the most severe human diseases, bubonic plague, which is caused by the Gram-negative bacterium Yersinia pestis. Our results demonstrate the safety and efficacy of LpxC inhibitors as a new class of antibiotic against fatal infections caused by extremely virulent pathogens. The present findings also highlight the potential of LpxC inhibitors for clinical development as therapeutics for infections caused by multidrug-resistant bacteria.

ClubSub-P: Cluster-Based Subcellular Localization Prediction for Gram-Negative Bacteria and Archaea

Science.gov (United States)

Paramasivam, Nagarajan; Linke, Dirk

2011-01-01

The subcellular localization (SCL) of proteins provides important clues to their function in a cell. In our efforts to predict useful vaccine targets against Gram-negative bacteria, we noticed that misannotated start codons frequently lead to wrongly assigned SCLs. This and other problems in SCL prediction, such as the relatively high false-positive and false-negative rates of some tools, can be avoided by applying multiple prediction tools to groups of homologous proteins. Here we present ClubSub-P, an online database that combines existing SCL prediction tools into a consensus pipeline from more than 600 proteomes of fully sequenced microorganisms. On top of the consensus prediction at the level of single sequences, the tool uses clusters of homologous proteins from Gram-negative bacteria and from Archaea to eliminate false-positive and false-negative predictions. ClubSub-P can assign the SCL of proteins from Gram-negative bacteria and Archaea with high precision. The database is searchable, and can easily be expanded using either new bacterial genomes or new prediction tools as they become available. This will further improve the performance of the SCL prediction, as well as the detection of misannotated start codons and other annotation errors. ClubSub-P is available online at http://toolkit.tuebingen.mpg.de/clubsubp/ PMID:22073040

Protein secretion and membrane insertion systems in gram-negative bacteria.

Science.gov (United States)

Saier, Milton H

2006-01-01

In contrast to other organisms, gram-negative bacteria have evolved numerous systems for protein export. Eight types are known that mediate export across or insertion into the cytoplasmic membrane, while eight specifically mediate export across or insertion into the outer membrane. Three of the former secretory pathway (SP) systems, type I SP (ISP, ABC), IIISP (Fla/Path) and IVSP (Conj/Vir), can export proteins across both membranes in a single energy-coupled step. A fourth generalized mechanism for exporting proteins across the two-membrane envelope in two distinct steps (which we here refer to as type II secretory pathways [IISP]) utilizes either the general secretory pathway (GSP or Sec) or the twin-arginine targeting translocase for translocation across the inner membrane, and either the main terminal branch or one of several protein-specific export systems for translocation across the outer membrane. We here survey the various well-characterized protein translocation systems found in living organisms and then focus on the systems present in gram-negative bacteria. Comparisons between these systems suggest specific biogenic, mechanistic and evolutionary similarities as well as major differences.

VIP as a potential therapeutic agent in gram negative sepsis.

Science.gov (United States)

Ibrahim, Hiba; Barrow, Paul; Foster, Neil

2012-12-01

Gram negative sepsis remains a high cause of mortality and places a great burden on public health finance in both the developed and developing world. Treatment of sepsis, using antibiotics, is often ineffective since pathology associated with the disease occurs due to dysregulation of the immune system (failure to return to steady state conditions) which continues after the bacteria, which induced the immune response, have been cleared. Immune modulation is therefore a rational approach to the treatment of sepsis but to date no drug has been developed which is highly effective, cheap and completely safe to use. One potential therapeutic agent is VIP, which is a natural peptide and is highly homologous in all vertebrates. In this review we will discuss the effect of VIP on components of the immune system, relevant to gram negative sepsis, and present data from animal models. Furthermore we will hypothesise on how these studies could be improved in future and speculate on the possible different ways in which VIP could be used in clinical medicine.

Associations of Eu(III) with Gram-negative bacteria, Alcaligenes faecalis, Shewanella putrefaciens, and Paracoccus denitrificans

International Nuclear Information System (INIS)

Ozaki, Takuo; Ohnuki, Toshihiko; Kimura, Takaumi; Francis, Arokiasamy J.

2005-01-01

We studied the association of Eu(III) with Gram-negative bacteria, Alcaligenes faecalis, Shewanella putrefaciens, and Paracoccus denitrificans by a batch method and time-resolved laser-induced fluorescence spectroscopy (TRLFS). The kinetics study showed that the Eu(III) adsorption on the bacteria rapidly proceeded. The Eu(III) adsorption on A. faecalis and P. denitrificans at pHs 3, 4, and 5, and that on S.putrefaciens at pHs 4 and 5 reached a maximum within 5 minutes after contact. For P. denitrificans, the percent adsorption of Eu(III) decreased after the maximum percent adsorption was attained, which suggests the existence of exudates with an affinity with Eu(III). TRLFS showed that the coordination of Eu(III) on these bacteria is multidentate through an inner-spherical process. The ligand field of Eu(III) on P. denitrificans was as strong as the ones observed for halophilic microorganisms, while that of A. faecalis and S. putrefaciens was the typical one observed for non-halophilic microorganisms. The coordination environment of Eu(III) on the bacteria differed from each other, though they are categorized as Gram-negative bacteria with the similar cell wall components. (author)

Effect of Light-Activated Hypocrellin B on the Growth and Membrane Permeability of Gram-Negative Escherichia coli Cells

Directory of Open Access Journals (Sweden)

Yuan Jiang

2014-01-01

Full Text Available Aim. To investigate the effect of light-activated hypocrellin B on the growth and membrane permeability of Gram-negative bacteria. Methods. Escherichia coli (E. coli as a model bacterium of Gram-negative bacteria was incubated with various concentrations of hypocrellin B for 60 min and was subsequently irradiated by blue light with wavelength of 470 nm at the dose of 12 J/cm2. Colony forming units were counted and the growth inhibition rate of E. coli cells was calculated after light-activated hypocrellin B. Membrane permeability was measured using flow cytometry and confocal laser scanning microscopy (CLSM with propidium iodide (PI staining. Bacterial morphology was observed using transmission electron microscopy (TEM. Reactive oxygen species in bacterial cells were measured using flow cytometry with DCFH-DA staining. Results. Significant growth inhibition rate of E. coli cells was observed after photodynamic action of hypocrellin B. Remarkable damage to the ultrastructure of E. coli was also observed by TEM. Flow cytometry and CLSM observation showed that light-activated hypocrellin B markedly increased membrane permeability of E. coli. Flow cytometry showed the intracellular ROS increase in E. coli treated by photodynamic action of hypocrellin B. Conclusion. Light-activated hypocrellin B caused intracellular ROS increase and structural damages and inhibited the growth of Gram-negative E. coli cells.

Metallo- β-lactamases among Multidrug Resistant (MDR Gram Negative Bacteria Isolated from Clinical Specimens during 2009 in Sanandaj, Kurdistan Province

Directory of Open Access Journals (Sweden)

Himen Salimizand

2012-08-01

Full Text Available Background: Today, there are numerous reports about emerging multi drug resistant gram negative bacteria all around the world, especially in ICUs. Rarely, Metallo-β-lactamase (MBL enzymes are responsible for these cases. Study of MBLs for diagnosing and preventing distribution of the origin of infection are critical issues. In addition, we would like to compare the efficacy of Iranian and foreign- made antibiotic disks. Materials and Methods: During 2009 all entered clinical specimens to the laboratory tested for detecting gram negative bacteria. Isolated bacteria were tested by Kirby-Bauer method to antibiotic susceptibility test by Iranian and foreign (MAST disks. For gram negative carbapenem resistant isolates, PCR technique used to detect VIM, GIM, and SIM variants of MBLs.Results: During one year, 17890 clinical specimens referred Besat laboratory. The most specimen was Urine (8172 followed by blood culture (5190 that in which 1110 gram negative and positives isolated. Out of which, 778 (70% of isolates were gram negatives. MDR gram negatives were 157 (20.2%. Imipenem and meropenem were the most efficient antibiotics (all susceptible and ceftriaxone was the least (19 % susceptible. E. coli was the most prevalent isolate. 79 Gram negative isolates (10.1% were resistant to Iranian-made discs but all susceptible for foreign ones. All 79 isolates were tested by PCR for MBL genes, that, all were negative. Besides, Iranian imipenem and cefepime disks have had distinguishable difference in susceptibility of isolates.Conclusion: Fortunately, none of gram negative isolates were MBL producer, which revealed no colonization of MBL producing bacteria. Iranian-made disks appear efficient except for imipenem and cefepime.

Biocidal Energetic Materials for the Destruction of Spore Forming Bacteria

Science.gov (United States)

2015-07-01

agent (GA). During a reaction the GA generates nucleation sites that promote the formation of bubbles. As the reaction wave passes, the gas pockets...studies have shown iodine producing reactive materials are effective against spore forming bacteria, but are sensitive to the relative humidity in the...testing environment. Results from tests run in relative high humidity environments show a decreased ability of iodine to effectively neutralize

Risk factors for carbapenem resistant bacteraemia and mortality due to gram negative bacteraemia in a developing country

International Nuclear Information System (INIS)

Kalam, K.; Kumar, S.; Ali, S.; Baqi, S.; Qamar, F.

2014-01-01

Objective: To identify the risk factors for carbapenem resistant bacteraemia and mortality due to gram negative bacteraemia in a developing country. Methods: A prospective cohort study was conducted at the Sindh Institute of Urology and Transplantation (SIUT) from June to October 2012. Hospitalized patients > 15 years of age with gram negative bacteraemia were included and followed for a period of 2 weeks for in hospital mortality. Data was collected and analyzed for 243 subjects. Multivariate analysis was used to determine the risk factors for carbapenem resistant bacteraemia and mortality due to gram negative bacteraemia. Crude and adjusted odds ratio and 95% CI are reported. Results: A total of 729 out of 1535 (47.5%) cultures were positive for gram negative isolates. Out of 243 subjects, 117 (48%) had an MDR isolate. Having an MDR isolate on culture (AOR, 2.33; 95% CI, 1.35 -4.0), having multiple positive cultures (AOR, 1.8; 95% CI, 0.94 -3.4) and stay in ICU >48 hours (AOR, 2.0 ; 95% CI, 1.12 -3.78) were identified as significant risk factors for mortality due to gram negative organisms. Risk factors for carbapenem resistant bacteraemia were age >50 years (AOR, 1.83; 95% CI, 1.0-3.5), septic shock on presentation (AOR 2.53; 95% CI, 1.03 -6.2) , ICU stay of >72 hours (AOR 2.40; 95% CI, 1.14-5.0) and receiving immunosuppressant medications (AOR 2.23; 95% CI, 0.74 - 6.7). Conclusion: There is a high burden of MDR and carbapenem resistant gram negative bacteraemia, with a high mortality rate. (author)

FLECHT-SEASET 21-rod bundle flow blockage heat transfer during reflood

International Nuclear Information System (INIS)

Loftus, M.; Hochreiter, L.; Lee, N.

1983-01-01

The effect of various flow blockage shapes and distributions during a PWR reflood was investigated using six 21-rod bundles with full length, internally heated, cosine power-shaped electrical rods. The flow blockage shapes, simulating the fuel rod clad ballooning, were made of thin-wall stainless steel tubes hydroformed into a short, concentric shape and along, nonconcentric shape. The blockage sleeves were distributed both coplanar, with all sleeves located at the same elevation, and non-coplanar. The initial and boundary conditions were varied to include parametric effects of pressure, inlet water temperature, and primarily, flooding rate. The initial mid-plane rod temperature was 871 0 C (1600 0 F) in all tests. Rod and vapor temperature measurements were made throughout the rod bundle with emphasis on the blockage region. The rod heat transfer downstream of the blockage was found to be greater for rods in a blocked bundle than for similar rods in an unblocked bundle. The heat transfer improvement decreases both with time after flood initiation and as the distance increased downstream of the blockage. The improvement in the heat transfer is attributed primarily to the breakup of the water droplets entrained in the steam flow. The smaller droplets subsequently evaporate and desuperheat the steam, which then improves the heat transfer between the rods and the steam in and downstream of the blockage zone

Isolation and characterization of two novel ethanol-tolerant facultative-anaerobic thermophilic bacteria strains from waste compost.

Science.gov (United States)

Fong, Jiunn C N; Svenson, Charles J; Nakasugi, Kenlee; Leong, Caine T C; Bowman, John P; Chen, Betty; Glenn, Dianne R; Neilan, Brett A; Rogers, Peter L

2006-10-01

In a search for potential ethanologens, waste compost was screened for ethanol-tolerant thermophilic microorganisms. Two thermophilic bacterial strains, M5EXG and M10EXG, with tolerance of 5 and 10% (v/v) ethanol, respectively, were isolated. Both isolates are facultative anaerobic, non-spore forming, non-motile, catalase-positive, oxidase-negative, Gram-negative rods that are capable of utilizing a range of carbon sources including arabinose, galactose, mannose, glucose and xylose and produce low amounts of ethanol, acetate and lactate. Growth of both isolates was observed in fully defined minimal media within the temperature range 50-80 degrees C and pH 6.0-8.0. Phylogenetic analysis of the 16S rDNA sequences revealed that both isolates clustered with members of subgroup 5 of the genus Bacillus. G+C contents and DNA-DNA relatedness of M5EXG and M10EXG revealed that they are strains belonging to Geobacillus thermoglucosidasius. However, physiological and biochemical differences were evident when isolates M5EXG and M10EXG were compared with G. thermoglucosidasius type strain (DSM 2542(T)). The new thermophilic, ethanol-tolerant strains of G. thermoglucosidasius may be candidates for ethanol production at elevated temperatures.

Subcellular localization for Gram positive and Gram negative bacterial proteins using linear interpolation smoothing model.

Science.gov (United States)

Saini, Harsh; Raicar, Gaurav; Dehzangi, Abdollah; Lal, Sunil; Sharma, Alok

2015-12-07

Protein subcellular localization is an important topic in proteomics since it is related to a protein׳s overall function, helps in the understanding of metabolic pathways, and in drug design and discovery. In this paper, a basic approximation technique from natural language processing called the linear interpolation smoothing model is applied for predicting protein subcellular localizations. The proposed approach extracts features from syntactical information in protein sequences to build probabilistic profiles using dependency models, which are used in linear interpolation to determine how likely is a sequence to belong to a particular subcellular location. This technique builds a statistical model based on maximum likelihood. It is able to deal effectively with high dimensionality that hinders other traditional classifiers such as Support Vector Machines or k-Nearest Neighbours without sacrificing performance. This approach has been evaluated by predicting subcellular localizations of Gram positive and Gram negative bacterial proteins. Copyright © 2015 Elsevier Ltd. All rights reserved.

A method for the determination of bacterial spore DNA content based on isotopic labelling, spore germination and diphenylamine assay; ploidy of spores of several Bacillus species

International Nuclear Information System (INIS)

Hauser, P.M.; Karamata, D.

1992-01-01

A reliable method for measuring the spore DNA content, based on radioactive DNA labelling, spore germination in absence of DNA replication and diphenylamine assay, was developed. The accuracy of the method, within 10 - 15%, is adequate for determining the number of chromosomes per spore, provided that the genome size is known. B subtilis spores were shown to be invariably monogenomic, while those of larger bacilli Bacillus megaterium, Bacillus cereus and Bacillus thuringiensis, often, if not invariably, contain two genomes. Attempts to modify the spore DNA content of B subtilis by altering the richness of the sporulation medium, the sporulation conditions (liquid or solid medium), or by mutation, were apparently unsuccessful. An increase of spore size with medium richness, not accompanied by an increase in DNA content, was observed. The implication of the apparently species-specific spore ploidy and the influence of the sporulation conditions on spore size and shape are discussed

The Role of Monitoring Gentamicin Levels in Patients with Gram-Negative Peritoneal Dialysis-Associated Peritonitis

Science.gov (United States)

Tang, Wen; Cho, Yeoungjee; Hawley, Carmel M.; Badve, Sunil V.; Johnson, David W.

2014-01-01

♦ Background: There is limited available evidence regarding the role of monitoring serum gentamicin concentrations in peritoneal dialysis (PD) patients receiving this antimicrobial agent in gram-negative PD-associated peritonitis. ♦ Methods: Using data collected in all patients receiving PD at a single center who experienced a gram-negative peritonitis episode between 1 January 2005 and 31 December 2011, we investigated the relationship between measured serum gentamicin levels on day 2 following initial empiric antibiotic therapy and subsequent clinical outcomes of confirmed gram-negative peritonitis. ♦ Results: Serum gentamicin levels were performed on day 2 in 51 (77%) of 66 first gram-negative peritonitis episodes. Average serum gentamicin levels on day 2 were 1.83 ± 0.84 mg/L with levels exceeding 2 mg/L in 22 (43%) cases. The overall cure rate was 64%. No cases of ototoxicity were observed. Day-2 gentamicin levels were not significantly different between patients who did and did not have a complication or cure. Using multivariable logistic regression analysis, failure to cure peritonitis was not associated with either day-2 gentamicin level (adjusted odds ratio (OR) 0.96, 95% confidence interval (CI) 0.25 - 3.73) or continuation of gentamicin therapy beyond day 2 (OR 0.28, 0.02 - 3.56). The only exception was polymicrobial peritonitis, where day-2 gentamicin levels were significantly higher in episodes that were cured (2.06 ± 0.41 vs 1.29 ± 0.71, p = 0.01). In 17 (26%) patients receiving extended gentamicin therapy, day-5 gentamicin levels were not significantly related to peritonitis cure. ♦ Conclusion: Day-2 gentamicin levels did not predict gentamicin-related harm or efficacy during short-course gentamicin therapy for gram-negative PD-related peritonitis, except in cases of polymicrobial peritonitis, where higher levels were associated with cure. PMID:24385334

Spore-forming, Desulfosporosinus-like sulphate-reducing bacteria from a shallow aquifer contaminated with gasoline.

Science.gov (United States)

Robertson, W J; Franzmann, P D; Mee, B J

2000-02-01

Previous studies on the geochemistry of a shallow unconfined aquifer contaminated with hydrocarbons suggested that the degradation of some hydrocarbons was linked to bacterial sulphate reduction. There was attenuation of naphthalene, 1,3,5-trimethylbenzene (TMB), toluene, p-xylene and ethylbenzene in the groundwater with concomitant loss of sulphate. Here, the recovery of eight strains of sulphate-reducing bacteria (SRB) from the contaminated site is reported. All were straight or curved rod-shaped cells which formed endospores. Amplification and sequencing of the 16S rDNA indicated that the strains were all sulphate reducers of the Gram-positive line of descent, and were most closely related to Desulfosporosinus (previously Desulfotomaculum) orientis DSM 8344 (97-98.9% sequence similarity). The strains clustered in three phylogenetic groups based on 16S rRNA sequences. Whole cell fatty acid compositions were similar to those of D. orientis DSM 8344, and were consistent with previous studies of fatty acids in soil and groundwater from the site. Microcosms containing groundwater from this aquifer indicated a role for sulphate reduction in the degradation of [ring-UL-14C]toluene, but not for the degradation of [UL-14C]benzene which could also be degraded by the microcosms. Adding one of the strains that was isolated from the groundwater (strain T2) to sulphate-enriched microcosms increased the rate of toluene degradation four- to 10-fold but had no effect on the rate of benzene degradation. The addition of molybdate, an inhibitor of sulphate reduction, to the groundwater samples decreased the rate of toluene mineralization. There was no evidence to support the mineralization of [UL-14C]benzene, [ring-UL-14C]toluene or unlabelled m-xylene, p-xylene, ethylbenzene, TMB or naphthalene by any of the strains in pure culture. Growth of all the strains was completely inhibited by 100 micromol l-1 TMB.

Nanostructured ZnO films in forms of rod, plate and flower: Electrodeposition mechanisms and characterization

International Nuclear Information System (INIS)

Kıcır, Nur; Tüken, Tunç; Erken, Ozge; Gumus, Cebrail; Ufuktepe, Yuksel

2016-01-01

Highlights: • Electrosynthesis of ZnO nanostructures in the form of plate, rod and flower. • The role of type and concentration of supporting electrolytes on growth mechanism. • Detailed analysis of morphologies, in comparison with the Literature. • Nanoplate form of ZnO exhibits higher Fermi level and lower band gap. - Abstract: Uniformity and reproducibility of well-defined ZnO nanostructures are particularly important issues for fabrication and applications of these nanomaterials. In present study, we report selective morphology control during electrodeposition, by adjusting the hydroxyl generation rate and Zn(OH)_2 deposition. In presence of remarkably high chloride concentration (0.3 M) and −1.0 V deposition potential, slow precipitation conditions were provided in 5 mM Zn(NO_3)_2 solution. By doing so, we have obtained highly ordered, vertically aligned and uniformly spaced hexagon shaped nanoplates, on ITO surface. We have also investigated the mechanism for shifting the morphology from rod/plate to flower like structure of ZnO, for better understanding the reproducibility. For this reason, the influence of various supporting electrolytes (sodium/ammonium salts of acetate) has been investigated for interpretation of the influence of OH"− concentration nearby the surface. From rod to plate and flower nanostructures, X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD) analysis were realized for characterization, also the optical properties were studied.

Nanostructured ZnO films in forms of rod, plate and flower: Electrodeposition mechanisms and characterization

Energy Technology Data Exchange (ETDEWEB)

Kıcır, Nur, E-mail: nurkicir@gmail.com [Chemistry Department, Çukurova University, 01330 Adana (Turkey); Tüken, Tunç [Chemistry Department, Çukurova University, 01330 Adana (Turkey); Erken, Ozge [Physics Department, Adiyaman University, 02040 Adıyaman (Turkey); Gumus, Cebrail; Ufuktepe, Yuksel [Physics Department, Çukurova University, 01330 Adana (Turkey)

2016-07-30

Highlights: • Electrosynthesis of ZnO nanostructures in the form of plate, rod and flower. • The role of type and concentration of supporting electrolytes on growth mechanism. • Detailed analysis of morphologies, in comparison with the Literature. • Nanoplate form of ZnO exhibits higher Fermi level and lower band gap. - Abstract: Uniformity and reproducibility of well-defined ZnO nanostructures are particularly important issues for fabrication and applications of these nanomaterials. In present study, we report selective morphology control during electrodeposition, by adjusting the hydroxyl generation rate and Zn(OH){sub 2} deposition. In presence of remarkably high chloride concentration (0.3 M) and −1.0 V deposition potential, slow precipitation conditions were provided in 5 mM Zn(NO{sub 3}){sub 2} solution. By doing so, we have obtained highly ordered, vertically aligned and uniformly spaced hexagon shaped nanoplates, on ITO surface. We have also investigated the mechanism for shifting the morphology from rod/plate to flower like structure of ZnO, for better understanding the reproducibility. For this reason, the influence of various supporting electrolytes (sodium/ammonium salts of acetate) has been investigated for interpretation of the influence of OH{sup −} concentration nearby the surface. From rod to plate and flower nanostructures, X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD) analysis were realized for characterization, also the optical properties were studied.

Reactor core with rod-shaped fuel cells

International Nuclear Information System (INIS)

Dworak, A.

1976-01-01

The proposal refers to the optimization of the power distribution in a reactor core which is provided with several successive rod-shaped fuel cells. A uniform power output - especially in radial direction - is aimed at. This is achieved by variation of the dwelling periods of the fuel cells, which have, for this purpose, a fuel mixture changing from layer to layer. The fuel cells with the shortest dwelling period are arranged near the coolant inlet side of the reactor core. The dwelling periods of the fuel cells are adapted to the given power distribution. As neighboring cells have equal dwelling periods, the exchange can be performed much easier then with the composition currently known. (UWI) [de

Interventional strategies and current clinical experience with carbapenemase-producing Gram-negative bacteria.

Science.gov (United States)

Akova, M; Daikos, G L; Tzouvelekis, L; Carmeli, Y

2012-05-01

The wide dissemination of carbapenemase-producing Gram-negatives (CPGNs), including enterobacterial species and non-fermenters, has caused a public health crisis of global dimensions. These organisms cause serious infections in hospitalized patients, and are associated with increased mortality. Cross-transmission is common, and outbreaks may occur in healthcare facilities where the infection control practices are inadequate. CPGNs exhibit extensive drug-resistant phenotypes, complicate therapy, and limit treatment options. Systematic data on therapy are limited. However, regimens combining two or more active agents seem to be more efficacious than monotherapy in carbapenemase-producing Klebsiella pneumoniae infections. Strict infection control measures, including active surveillance for timely detection of colonized patients, separation of carriers from non-carriers, and contact precautions, are of utmost importance, and may be the only effective way of preventing the introduction and transmission of these bacteria in healthcare settings. © 2012 The Authors. Clinical Microbiology and Infection © 2012 European Society of Clinical Microbiology and Infectious Diseases.

ClubSub-P: Cluster-based subcellular localization prediction for Gram-negative bacteria and Archaea.

Directory of Open Access Journals (Sweden)

Nagarajan eParamasivam

2011-11-01

Full Text Available The subcellular localization of proteins provides important clues to their function in a cell. In our efforts to predict useful vaccine targets against Gram-negative bacteria, we noticed that misannotated start codons frequently lead to wrongly assigned subcellular localizations. This and other problems in subcellular localization prediction, such as the relatively high false positive and false negative rates of some tools, can be avoided by applying multiple prediction tools to groups of homologous proteins. Here we present ClubSub-P, an online database that combines existing subcellular localization prediction tools into a consensus pipeline from more than 600 proteomes of fully sequenced microorganisms. On top of the consensus prediction at the level of single sequences, the tool uses clusters of homologous proteins from Gram-negative bacteria and from Archaea to eliminate false positive and false negative predictions. ClubSub-P can assign the subcellular localization of proteins from Gram-negative bacteria and Archaea with high precision. The database is searchable, and can easily be expanded using either new bacterial genomes or new prediction tools as they become available. This will further improve the performance of the subcellular localization prediction, as well as the detection of misannotated start codons and other annotation errors. ClubSub-P is available online at http://toolkit.tuebingen.mpg.de/clubsubp/

Structural modifications of bacterial lipopolysaccharide that facilitate Gram-negative bacteria evasion of host innate immunity

Directory of Open Access Journals (Sweden)

Motohiro eMatsuura

2013-05-01

Full Text Available Bacterial lipopolysaccharide (LPS, a cell wall component characteristic of Gram-negative bacteria, is a representative pathogen-associated molecular pattern that allows mammalian cells to recognize bacterial invasion and trigger innate immune responses. The polysaccharide moiety of LPS primary plays protective roles for bacteria such as prevention from complement attacks or camouflage with common host carbohydrate residues. The lipid moiety, termed lipid A, is recognized by the Toll-like receptor 4 (TLR4/MD-2 complex, which transduces signals for activation of host innate immunity. The basic structure of lipid A is a glucosamine disaccharide substituted by phosphate groups and acyl groups. Lipid A with 6 acyl groups (hexa-acylated form has been indicated to be a strong stimulator of the TLR4/MD-2 complex. This type of lipid A is conserved among a wide variety of Gram-negative bacteria, and those bacteria are easily recognized by host cells for activation of defensive innate immune responses. Modifications of the lipid A structure to less-acylated forms have been observed in some bacterial species, and those forms are poor stimulators of the TLR4/MD-2 complex. Such modifications are thought to facilitate bacterial evasion of host innate immunity, thereby enhancing pathogenicity. This hypothesis is supported by studies of Yersinia pestis LPS, which contains hexa-acylated lipid A when the bacterium grows at 27ºC (the temperature of the vector flea, and shifts to contain less-acylated forms when grown at the human body temperature of 37ºC. This alteration of lipid A forms following transmission of Y. pestis from fleas to humans contributes predominantly to the virulence of this bacterium over other virulence factors. A similar role for less-acylated lipid A forms has been indicated in some other bacterial species, such as Francisella tularensis, Helicobacter pylori, and Porphyromonas gingivalis, and further studies to explore this concept are

Genome sequence and description of Anaeromassilibacillus senegalensis gen. nov., sp. nov., isolated from the gut of patient with kwashiorkor

Directory of Open Access Journals (Sweden)

E. Guilhot

2017-05-01

Full Text Available Using the culturomics strategy, a wide range of anaerobic bacteria was discovered including Anaeromassilibacillus senegalensis strain mt9T (= CSUR P1511=DSM 102954, isolated from the gut microbiota of a 1-year-old Senegalese patient with kwashiorkor. This Gram-negative strain is a strictly anaerobic, spore-forming rod motile by a polar flagellum. The 3 511 289 bp long genome of this strain contains 3046 protein-coding and 49 RNA genes, including 45 tRNA and four rRNA genes, and exhibits a G+C content of 52.94%. Here we describe the features of this organism, together with the complete genome sequence and annotation.

Characterization of newly isolated Lactobacillus delbrueckii-like strain MF-07 isolated from chicken and its role in isoflavone biotransformation.

Science.gov (United States)

Iqbal, Muhammad Farooq; Zhu, Wei-Yun

2009-02-01

Cecal microbiota of chicken was screened for bacteria involved in the biotransformation of isoflavones. A new facultative anaerobic bacterium, capable of deglycosylation of the isoflavone genistin, was isolated and identified as a Lactobacillus delbrueckii-like strain. The isolate MF-07 was Gram-positive, facultatively anaerobic, catalase negative, non-spore-forming, nonmotile and a straight rod. The polyphasic taxonomic data, along with 16S rRNA gene sequence comparison, demonstrated that the isolate MF-07 was most closely related to L. delbrueckii group of the Lactobacillus genus. Considerable amounts of genistein were accumulated with genistin as a substrate within the first 12 h of fermentation. Formononetin and daidzein were not metabolized. The influence of several carbon sources on the growth of the isolate MF-07 and biotransformation of genistin was also investigated. This is the first study in which an anaerobic Lactobacillus bacterium from the chicken intestinal tract that metabolizes genistin to produce its bioactive metabolite was identified and characterized.

SHORT COMMUNICATION: Non-Fermenters in Human Infections with Special Reference to Acinetobacter Species in a Tertiary Care Hospital from North Karnataka, India

Directory of Open Access Journals (Sweden)

Prashant K. Parandekar

2012-01-01

Full Text Available Background: Non-fermenters are a group of aerobic non-spore forming gram negative bacilli that are either incapable of utilizingcarbohydrates as a source of energy or degrade them via oxidative rather than fermentative pathway. These are increasingly been reported from the cases of nosocomial infections. Aims and Objectives: This study was undertaken aiming to identify, characterize all nonfermenters and further study of Acinetobacterisolates. Materials and Methods: A total 116 non-fermenters isolated from various specimens obtained from the patients in tertiarycare hospital. Gram negative bacilli which failed to produce acid on Triple Sugar Iron Agar (TSI were identified by employing battery oftests. The Acinetobacter isolates were further speciated and antimicrobial susceptibility testing done by Kirby Bauer disc diffusion technique. Results: Non-fermenters isolated were Pseudomonas aerugionsa (69.8%, Acinetobacter species (18.9%,Stenotrophomonas maltophilia (4.3%, Burkholderia cepacia (3.4%, Alcaligenes fecalis (1.7% and Pseudomonas fluorescens (1.7%. Most of the isolates showed susceptibility to imipenem (86.3% whereasnone of the isolates were sensitive to cephalexin and co-trimoxazole. Conclusion: This study highlights that, after Pseudomonas aeruginosa, Acinetobacter species is the most common non-fermenter. Majority of the isolates of Acinetobacter Species were ofnosocomial origin and were multidrug resistant, which underlines the importance of proper vigilance of these infections in hospital setting.

The Toll pathway underlies host sexual dimorphism in resistance to both Gram-negative and Gram-positive bacteria in mated Drosophila.

Science.gov (United States)

Duneau, David F; Kondolf, Hannah C; Im, Joo Hyun; Ortiz, Gerardo A; Chow, Christopher; Fox, Michael A; Eugénio, Ana T; Revah, J; Buchon, Nicolas; Lazzaro, Brian P

2017-12-21

Host sexual dimorphism is being increasingly recognized to generate strong differences in the outcome of infectious disease, but the mechanisms underlying immunological differences between males and females remain poorly characterized. Here, we used Drosophila melanogaster to assess and dissect sexual dimorphism in the innate response to systemic bacterial infection. We demonstrated sexual dimorphism in susceptibility to infection by a broad spectrum of Gram-positive and Gram-negative bacteria. We found that both virgin and mated females are more susceptible than mated males to most, but not all, infections. We investigated in more detail the lower resistance of females to infection with Providencia rettgeri, a Gram-negative bacterium that naturally infects D. melanogaster. We found that females have a higher number of phagocytes than males and that ablation of hemocytes does not eliminate the dimorphism in resistance to P. rettgeri, so the observed dimorphism does not stem from differences in the cellular response. The Imd pathway is critical for the production of antimicrobial peptides in response to Gram-negative bacteria, but mutants for Imd signaling continued to exhibit dimorphism even though both sexes showed strongly reduced resistance. Instead, we found that the Toll pathway is responsible for the dimorphism in resistance. The Toll pathway is dimorphic in genome-wide constitutive gene expression and in induced response to infection. Toll signaling is dimorphic in both constitutive signaling and in induced activation in response to P. rettgeri infection. The dimorphism in pathway activation can be specifically attributed to Persephone-mediated immune stimulation, by which the Toll pathway is triggered in response to pathogen-derived virulence factors. We additionally found that, in absence of Toll signaling, males become more susceptible than females to the Gram-positive Enterococcus faecalis. This reversal in susceptibility between male and female Toll

Doripenem: an expected arrival in the treatment of infections caused by multidrug-resistant Gram-negative pathogens.

Science.gov (United States)

Poulakou, Garyphallia; Giamarellou, Helen

2008-05-01

Potent new drugs against multidrug-resistant Gram-negative bacteria, namely Pseudomonas aeruginosa and Acinetobacter spp. and pan-drug-resistant Klebsiella pneumoniae, which constitute an increasing medical threat, are almost absent from the future pharmaceutical pipeline. This drug evaluation focuses on the position of doripenem, a novel forthcoming carbapenem. Mechanisms of resistance and new drugs with anti-Gram-negative activity are also briefly reviewed. Literature search was performed for new carbapenems, new antibiotics, doripenem, metallo-beta-lactamase inhibitors, multidrug-resistant pathogens, antipseudomonal antibiotics and multidrug-resistant epidemiology. Doripenem possesses a broad spectrum of activity against Gram-negative bacteria, similar to that of meropenem, while retaining the spectrum of imipenem against Gram-positive pathogens. Against P. aeruginosa, doripenem exhibits rapid bactericidal activity with 2 - 4-fold lower MIC values, compared to meropenem. Exploitation of pharmacokinetic/pharmacodynamic applications could offer a treatment opportunity against strains exhibiting borderline resistance to doripenem. Stability against numerous beta-lactamases, low adverse event potential and more potent in vitro antibacterial activity against P. aeruginosa and A. baumanni compared to the existing carbapenems, are its principal features.

Lack of clinical utility of urine gram stain for suspected urinary tract infection in pediatric patients.

Science.gov (United States)

Cantey, Joseph B; Gaviria-Agudelo, Claudia; McElvania TeKippe, Erin; Doern, Christopher D

2015-04-01

Urinary tract infection (UTI) is one of the most common infections in children. Urine culture remains the gold standard for diagnosis, but the utility of urine Gram stain relative to urinalysis (UA) is unclear. We reviewed 312 pediatric patients with suspected UTI who had urine culture, UA, and urine Gram stain performed from a single urine specimen. UA was considered positive if ≥10 leukocytes per oil immersion field were seen or if either nitrates or leukocyte esterase testing was positive. Urine Gram stain was considered positive if any organisms were seen. Sensitivity, specificity, and positive and negative predictive values were calculated using urine culture as the gold standard. Thirty-seven (12%) patients had a culture-proven UTI. Compared to urine Gram stain, UA had equal sensitivity (97.3% versus 97.5%) and higher specificity (85% versus 74%). Empirical therapy was prescribed before the Gram stain result was known in 40 (49%) patients and after in 42 (51%) patients. The antibiotics chosen did not differ between the two groups (P=0.81), nor did they differ for patients with Gram-negative rods on urine Gram stain compared to those with Gram-positive cocci (P=0.67). From these data, we conclude that UA has excellent negative predictive value that is not enhanced by urine Gram stain and that antibiotic selection did not vary based on the urine Gram stain result. In conclusion, the clinical utility of urine Gram stain does not warrant the time or cost it requires. Copyright © 2015, American Society for Microbiology. All Rights Reserved.

Characterization of carbapenem-resistant Gram-negative bacteria from Tamil Nadu.

Science.gov (United States)

Nachimuthu, Ramesh; Subramani, Ramkumar; Maray, Suresh; Gothandam, K M; Sivamangala, Karthikeyan; Manohar, Prasanth; Bozdogan, Bülent

2016-10-01

Carbapenem resistance is disseminating worldwide among Gram-negative bacteria. The aim of this study was to identify carbapenem-resistance level and to determine the mechanism of carbapenem resistance among clinical isolates from two centres in Tamil Nadu. In the present study, a total of 93 Gram-negative isolates, which is found to be resistant to carbapenem by disk diffusion test in two centres, were included. All isolates are identified at species level by 16S rRNA sequencing. Minimal inhibitory concentrations (MICs) of isolates for Meropenem were tested by agar dilution method. Presence of blaOXA, blaNDM, blaVIM, blaIMP and blaKPC genes was tested by PCR in all isolates. Amplicons were sequenced for confirmation of the genes. Among 93 isolates, 48 (%52) were Escherichia coli, 10 (%11) Klebsiella pneumoniae, nine (%10) Pseudomonas aeruginosa. Minimal inhibitory concentration results showed that of 93 suspected carbapenem-resistant isolates, 27 had meropenem MICs ≥ 2 μg/ml. The MIC range, MIC50 and MIC90 were 128 μg/ml, 0.12 and 16 μg/ml, respectively. Fig. 1 . Among meropenem-resistant isolates, E. coli were the most common (9/48, 22%), followed by K. pneumoniae (7/9, 77%), P. aeruginosa (6/10, 60%), Acinetobacter baumannii (2/2, 100%), Enterobacter hormaechei (2/3, 67%) and one Providencia rettgeri (1/1, 100%). PCR results showed that 16 of 93 carried blaNDM, three oxa181, and one imp4. Among blaNDM carriers, nine were E. coli, four Klebsiella pneumoniae, two E. hormaechei and one P. rettgeri. Three K. pneumoniae were OXA-181 carriers. The only imp4 carrier was P. aeruginosa. A total of seven carbapenem-resistant isolates were negatives by PCR for the genes studied. All carbapenem-resistance gene-positive isolates had meropenem MICs >2 μg/ml. Our results confirm the dissemination of NDM and emergence of OXA-181 beta-lactamase among Gram-negative bacteria in South India. This study showed the emergence of NDM producer in clinical isolates of E

Resistant gram-negative bacilli and antibiotic consumption in zarqa, jordan

International Nuclear Information System (INIS)

Bataineh, H.A.; Alrashed, K.M.

2007-01-01

To investigate the prevalence of antibiotic resistance among gram-negative bacteria in relation to antibiotic use in Prince Hashem Hospital (PHH), Jordan. One hundred consecutive gram-negative bacterial isolates from different sites were collected from patients admitted to the ICU at PHH. The susceptibilities of the strains to 12 antibiotics were performed and interpreted. The quantities and the numbers of the patients discharged on antibiotics and the quantities consumed were obtained from the hospital pharmacy records. The most common isolate was P. aeruginosa (n=21) The most common site of isolation was the respiratory tract (65%), The highest susceptibility was to piperacillin/ tazobactam(78%), and the lowest was to cefuroxime(34%). The aminoglycosides gentamicin and amikacin were active against 71% and 73% of the isolates respectively, Ciprofloxacin was active against 75% of the isolates. The most frequently used antibiotics were the third-generation cephalosporins ceftriaxone and ceftazidime, followed by imipenem and amikacin. Antibiotic resistance surveillance programs associated with registration of antibiotic consumption are necessary to promote optimal use of antibiotics. Rational prescribing of antibiotics should be encouraged through educational programs, surveillance and audit. Proper infection control measures should be practiced to prevent horizontal transfer of drug-resistant organisms. (author)

Comparison of the Cathra Repliscan II, the AutoMicrobic system Gram-Negative General Susceptibility-Plus Card, and the Micro-Media System Fox Panel for dilution susceptibility testing of gram-negative bacilli.

Science.gov (United States)

Reiber, N E; Kelly, M T; Latimer, J M; Tison, D L; Hysmith, R M

1985-06-01

A comparative evaluation was done to test the accuracy of the Cathra Repliscan II agar dilution system (Diagnostic Equipment, Inc., St. Paul, Minn.), the AutoMicrobic system with Gram-Negative General Susceptibility-Plus Card (Vitek Systems, Inc., Hazelwood, Mo.), and the Micro-Media Fox Panel micro broth dilution system (Micro-Media Systems, Inc., San Jose, Calif.) in determining MICs of 12 antibiotics for 200 gram-negative bacilli. Of the 200 strains tested, 12 isolates did not grow in one of the three systems. The 188 remaining organisms included 158 members of the family Enterobacteriaceae, 20 Pseudomonas spp., 5 Acinetobacter sp., 3 Aeromonas spp., and 2 Vibrio spp. A total of 2,256 organism-antibiotic combinations were analyzed for each system. An MIC was considered correct if two of the three systems were in agreement. When disagreements occurred, correct MICs were determined by the standard agar dilution method. With this criterion, overall agreements of the Cathra Repliscan II system, AutoMicrobic system, and Micro-Media Fox Panel system were 94.7, 94.9, and 95.5%, respectively. Tetracycline (20%), nitrofurantoin (20%), and ampicillin (16%) accounted for 56% of the discrepancies observed. These results indicate that all three systems perform with a high degree of accuracy for susceptibility testing of gram-negative bacilli.

PCR detection of thermophilic spore-forming bacteria involved in canned food spoilage.

Science.gov (United States)

Prevost, S; Andre, S; Remize, F

2010-12-01

Thermophilic bacteria that form highly heat-resistant spores constitute an important group of spoilage bacteria of low-acid canned food. A PCR assay was developed in order to rapidly trace these bacteria. Three PCR primer pairs were designed from rRNA gene sequences. These primers were evaluated for the specificity and the sensitivity of detection. Two primer pairs allowed detection at the species level of Geobacillus stearothermophilus and Moorella thermoacetica/thermoautrophica. The other pair allowed group-specific detection of anaerobic thermophilic bacteria of the genera Thermoanaerobacterium, Thermoanaerobacter, Caldanerobium and Caldanaerobacter. After a single enrichment step, these PCR assays allowed the detection of 28 thermophiles from 34 cans of spoiled low-acid food. In addition, 13 ingredients were screened for the presence of these bacteria. This PCR assay serves as a detection method for strains able to spoil low-acid canned food treated at 55°C. It will lead to better reactivity in the canning industry. Raw materials and ingredients might be qualified not only for quantitative spore contamination, but also for qualitative contamination by highly heat-resistant spores.

Fuel rod attachment system

International Nuclear Information System (INIS)

Christiansen, D.W.

1982-01-01

A reusable system for removably attaching a nuclear reactor fuel rod to a support member. A locking cap is secured to the fuel rod and a locking strip is fastened to the support member or vice versa. The locking cap has two opposing fingers and shaped to form a socket having a body portion. The locking strip has an extension shaped to rigidly attach to the socket's body portion. The locking cap's fingers are resiliently deflectable. For attachment, the locking cap is longitudinally pushed onto the locking strip causing the extension to temporarily deflect open the fingers to engage the socket's body portion. For removal, the process is reversed. In an alternative embodiment, the cap is rigid and the strip is transversely resiliently compressible. (author)

Trojan Horse Antibiotics-A Novel Way to Circumvent Gram-Negative Bacterial Resistance?

Science.gov (United States)

Tillotson, Glenn S

2016-01-01

Antibiotic resistance has been emerged as a major global health problem. In particular, gram-negative species pose a significant clinical challenge as bacteria develop or acquire more resistance mechanisms. Often, these bacteria possess multiple resistance mechanisms, thus nullifying most of the major classes of drugs. Novel approaches to this issue are urgently required. However, the challenges of developing new agents are immense. Introducing novel agents is fraught with hurdles, thus adapting known antibiotic classes by altering their chemical structure could be a way forward. A chemical addition to existing antibiotics known as a siderophore could be a solution to the gram-negative resistance issue. Siderophore molecules rely on the bacterial innate need for iron ions and thus can utilize a Trojan Horse approach to gain access to the bacterial cell. The current approaches to using this potential method are reviewed.

Gram-negative bacteria account for main differences between faecal microbiota from patients with ulcerative colitis and healthy controls

DEFF Research Database (Denmark)

Vigsnæs, Louise Kristine; Brynskov, J.; Steenholdt, C.

2012-01-01

process of the gut mucosa. The aim of this study was to investigate the faecal microbiota in patients either with UC in remission (n=6) or with active disease (n=6), and in healthy controls (n=6). The composition of Gram-negative bacteria and Gram-positive bacteria was examined. Antigenic structures...... of Gram-negative bacteria such as lipopolysaccharides have been related to the inflammatory responses and pathogenesis of inflammatory bowel disease. Dice cluster analysis and principal component analysis of faecal microbiota profiles obtained by denaturing gradient gel electrophoresis and quantitative...... PCR, respectively, revealed that the composition of faecal bacteria from UC patients with active disease differed from the healthy controls and that this difference should be ascribed to Gram-negative bacteria. The analysis did not show any clear grouping of UC patients in remission. Even...

Inactivation dynamics of 222 nm krypton-chlorine excilamp irradiation on Gram-positive and Gram-negative foodborne pathogenic bacteria.

Science.gov (United States)

Kang, Jun-Won; Kim, Sang-Soon; Kang, Dong-Hyun

2018-07-01

The object of this study was to elucidate the bactericidal mechanism of a 222 nm Krypton Chlorine (KrCl) excilamp compared with that of a 254 nm Low Pressure mercury (LP Hg) lamp. The KrCl excilamp had higher bactericidal capacity against Gram-positive pathogenic bacteria (Staphylococcus aureus and L. monocytogenes) and Gram-negative pathogenic bacteria (S. Typhimurium and E. coli O157:H7) than did the LP Hg lamp when cell suspensions in PBS were irradiated with each type of UV lamp. It was found out that the KrCl excilamp induced cell membrane damage as a form of depolarization. From the study of respiratory chain dehydrogenase activity and the lipid peroxidation assay, it was revealed that cell membrane damage was attributed to inactivation of enzymes related to generation of membrane potential and occurrence of lipid peroxidation. Direct absorption of UV radiation which led to photoreaction through formation of an excited state was one of the causes inducing cell damage. Additionally, generation of ROS and thus occurrence of secondary damage can be another cause. The LP Hg lamp only induced damage to DNA but not to other components such as lipids or proteins. This difference was derived from differences of UV radiation absorption by cellular materials. Copyright © 2018 Elsevier Ltd. All rights reserved.

Survey on Heterotrophic Bacterial Contamination in Bottled Mineral Water by Culture Method

Directory of Open Access Journals (Sweden)

Essmaeel Ghorbanalinezhad

2014-12-01

Full Text Available Background and Aim: This project focuses on the level of heterotrophic baceria in bottled mineral water which could be a health concern for the elderly, infants, pregnant women and immuno-compromised patients. Materials and Methods: Different brands of bottled water samples were selected randomly and evaluated for their bacteriological quality, using different specific culture media and biochemical tests. Water samples were analyzed within 24 hours of their purchase/collection. Samples were filtered with 0.45 micron and filters were plated in different media. Then media were incubated at 37˚C for 24-48 hours. Results: Morphological study and biochemical tests revealed a number of bacteria in different   brands of  bottled water. Heterotrophic bacteria(Gram positive cocci, Spore forming gram positive bacilli, non spore forming gram positive bacilli, gram negative bacilli, and gram negative coccobacilli; Pseudomonas and Stenotrophomonas counted in 70% of bottled water samples. There were no cases of fecal contamination or the presence of E.coli. Conclusions: Bottled water is not sterile and contains trace amounts of bacteria naturally present or introduced during processing. Testing drinking water for all possible pathogens is complex, time-consuming, and expensive. If only total coliform bacteria are detected in drinking water, the source is probably environmental. Since the significance of non-pathogenic heterotrophic bacteria in relation to health and diseases is not understood, there is an urgent need to establish a maximum limit for the heterotrophic count in the bottled mineral water. Growth conditions play a critical role in the recovery of heterotrophic bacteria in bottled drinking water.

DMPD: Gram-negative endotoxin: an extraordinary lipid with profound effects oneukaryotic signal transduction. [Dynamic Macrophage Pathway CSML Database

Lifescience Database Archive (English)

Full Text Available 1916089 Gram-negative endotoxin: an extraordinary lipid with profound effects oneuk...ep;5(12):2652-60. (.png) (.svg) (.html) (.csml) Show Gram-negative endotoxin: an extraordinary lipid with profound effects...tive endotoxin: an extraordinary lipid with profound effects oneukaryotic signal transduction. Authors Raetz

Chitinophaga rhizosphaerae sp. nov., isolated from rhizosphere soil of a tomato plant.

Science.gov (United States)

Kim, Soo-Jin; Cho, Hayoung; Ahn, Jae-Hyung; Weon, Hang-Yeon; Joa, Jae-Ho; Hong, Seung-Beom; Seok, Soon-Ja; Kim, Jeong-Seon; Kwon, Soon-Wo

2017-09-01

An aerobic, Gram-stain-negative, non-spore-forming, non-flagellated, rod-shaped or filamentous bacterial strain, T16R-86T, was isolated from rhizosphere of a tomato plant collected from a farm on Buyeo-gun, Chungcheongnam-do, South Korea. It grew at the temperature range 10-37 °C (optimum, 28 °C) and pH range 6.0-9.0 (optimum, pH 7.0), and tolerated up to 2 % (w/v) NaCl. According to 16S rRNA gene sequence analysis, strain T16R-86T shared the highest similarity with Chitinophaga barathri YLT18T (96.8 %) and C. pinensis DSM 2588T (96.7 %), forming a subcluster with C. barathri YLT18T, C. cymbidii R156-2T and C. niabensis JS13-10T in the phylogenetic tree. The major fatty acids were iso-C15 : 0, C16 : 1ω5c and iso-C17 : 0 3-OH. The predominant respiratory quinone was menaquinone MK-7. Polar lipids were phosphatidylethanolamine, five unknown aminolipids, an unknown aminophospholipid, one unknown phospholipid and two unknown lipids. The DNA G+C content was 53.6 mol%. The phenotypic, chemotaxonomic and phylogenetic data showed that strain T16R-86T represents a novel species of the genus Chitinophaga, for which the name Chitinophaga rhizosphaerae sp. nov. is proposed. The type strain is T16R-86T (=KACC 18790T=JCM 31600T).

Higher order structure in the 3'-minor domain of small subunit ribosomal RNAs from a gram negative bacterium, a gram positive bacterium and a eukaryote

DEFF Research Database (Denmark)

Douthwaite, S; Christensen, A; Garrett, R A

1983-01-01

of additional higher order structure in the renatured free RNA. It can be concluded that a high level of conservation of higher order structure has occurred during the evolution of the gram negative and gram positive eubacteria and the eukaryote in both the double helical regions and the "unstructured" regions...

Gram-Negative Infections in Adult Intensive Care Units of Latin America and the Caribbean

Directory of Open Access Journals (Sweden)

Carlos M. Luna

2014-01-01

Full Text Available This review summarizes recent epidemiology of Gram-negative infections in selected countries from Latin American and Caribbean adult intensive care units (ICUs. A systematic search of the biomedical literature (PubMed was performed to identify articles published over the last decade. Where appropriate, data also were collected from the reference list of published articles, health departments of specific countries, and registries. Independent cohort data from all countries (Argentina, Brazil, Chile, Colombia, Cuba, Mexico, Trinidad and Tobago, and Venezuela signified a high rate of ICU infections (prevalence: Argentina, 24%; Brazil, 57%. Gram-negative pathogens, predominantly Acinetobacter baumannii, Klebsiella pneumoniae, Pseudomonas aeruginosa, and Escherichia coli, accounted for >50% of ICU infections, which were often complicated by the presence of multidrug-resistant strains and clonal outbreaks. Empirical use of antimicrobial agents was identified as a strong risk factor for resistance development and excessive mortality. Infection control strategies utilizing hygiene measures and antimicrobial stewardship programs reduced the rate of device-associated infections. To mitigate the poor health outcomes associated with infections by multidrug-resistant Gram-negative bacteria, urgent focus must be placed on infection control strategies and local surveillance programs.

Synergistic antibacterial effect of silver and ebselen against multidrug-resistant Gram-negative bacterial infections.

Science.gov (United States)

Zou, Lili; Lu, Jun; Wang, Jun; Ren, Xiaoyuan; Zhang, Lanlan; Gao, Yu; Rottenberg, Martin E; Holmgren, Arne

2017-08-01

Multidrug-resistant (MDR) Gram-negative bacteria account for a majority of fatal infections, and development of new antibiotic principles and drugs is therefore of outstanding importance. Here, we report that five most clinically difficult-to-treat MDR Gram-negative bacteria are highly sensitive to a synergistic combination of silver and ebselen. In contrast, silver has no synergistic toxicity with ebselen on mammalian cells. The silver and ebselen combination causes a rapid depletion of glutathione and inhibition of the thioredoxin system in bacteria. Silver ions were identified as strong inhibitors of Escherichia coli thioredoxin and thioredoxin reductase, which are required for ribonucleotide reductase and DNA synthesis and defense against oxidative stress. The bactericidal efficacy of silver and ebselen was further verified in the treatment of mild and acute MDR E. coli peritonitis in mice. These results demonstrate that thiol-dependent redox systems in bacteria can be targeted in the design of new antibacterial drugs. The silver and ebselen combination offers a proof of concept in targeting essential bacterial systems and might be developed for novel efficient treatments against MDR Gram-negative bacterial infections. © 2017 The Authors. Published under the terms of the CC BY 4.0 license.

The Luna stain, an improved selective stain for detection of microsporidian spores in histologic sections

Science.gov (United States)

Peterson, Tracy S.; Spitsbergen, Jan M.; Feist, Stephen W.; Kent, Michael L.

2014-01-01

Microsporidia in histologic sections are most often diagnosed by observing spores in host tissues. Spores are easy to identify if they occur in large aggregates or xenomas when sections are stained with hematoxylin and eosin (H&E). However, individual spores are not frequently detected in host tissues with conventional H&E staining, particularly if spores are scattered within the tissues, areas of inflammation or small spores in nuclei (i.e., Nucleospora salmonis). Hence, a variety of selective stains that enhance visualization of spores are recommended. We discovered that the Luna stain, used to highlight eosinophils, red blood cells and chitin in arthropods and other invertebrates, also stains spores of Pseudoloma neurophilia. We compared this stain to the Gram, Fite’s acid fast, Giemsa, and H&E stains on eight aquatic microsporidian organisms that were readily available in our two laboratories: Loma salmonae, Glugea anomala, Pseudoloma neurophilia, Pleistophora hyphessobryconis, Pleistophora vermiformis, Glugea sp., Steinhausia mytilovum and an unidentified microsporidian from E. sinensis, UK. Based on tinctorial properties and background staining, the Luna stain performed better for detection of 6 of the 8 microsporidia. Gram stain was superior for the two microsporidia from invertebrates, Steinhausia mytilovum and the unidentified microsporidian from E. sinensis. PMID:21848126

Gelation And Mechanical Response of Patchy Rods

Science.gov (United States)

Kazem, Navid; Majidi, Carmel; Maloney, Craig

We perform Brownian Dynamics simulations to study the gelation of suspensions of attractive, rod-like particles. We show that details of the particle-particle interactions can dramatically affect the dynamics of gelation and the structure and mechanics of the networks that form. If the attraction between the rods is perfectly smooth along their length, they will collapse into compact bundles. If the attraction is sufficiently corrugated or patchy, over time, a rigid space spanning network forms. We study the structure and mechanical properties of the networks that form as a function of the fraction of the surface that is allowed to bind. Surprisingly, the structural and mechanical properties are non-monotonic in the surface coverage. At low coverage, there are not a sufficient number of cross-linking sites to form networks. At high coverage, rods bundle and form disconnected clusters. At intermediate coverage, robust networks form. The elastic modulus and yield stress are both non-monotonic in the surface coverage. The stiffest and strongest networks show an essentially homogeneous deformation under strain with rods re-orienting along the extensional axis. Weaker, clumpy networks at high surface coverage exhibit relatively little re-orienting with strong non-affine deformation. These results suggest design strategies for tailoring surface interactions between rods to yield rigid networks with optimal properties. National Science Foundation and the Air Force Office of Scientific Research.

Bio sorption of some Rare Earth Elements and Yttrium by Gram Positive and Gram Negative Bacteria

International Nuclear Information System (INIS)

Ibrahim, H.A.

2012-01-01

The separate bio sorption of the REEs La, Sm, Eu and Dy together with yttrium upon the Gram positive bacteria Bacillus subtilis (B.subtilis) and Bacillus Licheniformis (B. Licheniformis),the Gram negative bacterium Escherichia coli (E. coli ) and Saccharomyces cervisiae (Yeast) was studied. The revelant factors of ph 1-6, contact time (30-180 min), the initial rare earth concentration (50-200 mg/l) have been studied. The amount of the accumulated element was strongly affected by its concentration.In addition, bio sorptive fractionation of Y and the studied REEs from a solution containing a mixture of these elements was also studied. From the obtained data, it was found that Langmuir isotherm model for both B.licheniformis and E.coli gives a best fit for the studied elements over the working range of concentration (50-200 mg/I). Transmission electron microscopy exhibited accumulation throughout the bacterial cell with some granular deposits in both the cell periphery and cytoplasm

Antibiotic susceptibility of Gram-negatives isolated from bacteremia in children with cancer. Implications for empirical therapy of febrile neutropenia.

Science.gov (United States)

Castagnola, Elio; Caviglia, Ilaria; Pescetto, Luisa; Bagnasco, Francesca; Haupt, Riccardo; Bandettini, Roberto

2015-01-01

Monotherapy is recommended as the first choice for initial empirical therapy of febrile neutropenia, but local epidemiological and antibiotic susceptibility data are now considered pivotal to design a correct management strategy. To evaluate the proportion of Gram-negative rods isolated in bloodstream infections in children with cancer resistant to antibiotics recommended for this indication. The in vitro susceptibility to ceftazidime, piperacillin-tazobactam, meropenem and amikacin of Gram-negatives isolated in bacteremic episodes in children with cancer followed at the Istituto "Giannina Gaslini", Genoa, Italy in the period of 2001-2013 was retrospectively analyzed using the definitions recommended by EUCAST in 2014. Data were analyzed for any single drug and to the combination of amikacin with each β-lactam. The combination was considered effective in absence of concomitant resistance to both drugs, and not evaluated by means of in vitro analysis of antibiotic combinations (e.g., checkerboard). A total of 263 strains were evaluated: 27% were resistant to piperacillin-tazobactam, 23% to ceftazidime, 12% to meropenem and 13% to amikacin. Concomitant resistance to β-lactam and amikacin was detected in 6% of strains for piperacillin-tazobactam, 5% for ceftazidime and 5% for meropenem. During the study period there was a nonsignificant increase in the proportions of strains resistant to β-lactams indicated for monotherapy, and also increase in the resistance to combined therapies. in an era of increasing resistance to antibiotics guideline-recommended monotherapy could be not appropriate for initial empirical therapy of febrile neutropenia. Strict local survey on etiology and antibiotic susceptibility is mandatory for a correct management of this complication in cancer patients.

Fastidious Gram-Negatives: Identification by the Vitek 2 Neisseria-Haemophilus Card and by Partial 16S rRNA Gene Sequencing Analysis

DEFF Research Database (Denmark)

Wolff Sönksen, Ute; Christensen, Jens Jørgen; Nielsen, Lisbeth

2010-01-01

Taxonomy and identification of fastidious Gram negatives are evolving and challenging. We compared identifications achieved with the Vitek 2 Neisseria-Haemophilus (NH) card and partial 16S rRNA gene sequence (526 bp stretch) analysis with identifications obtained with extensive phenotypic...... characterization using 100 fastidious Gram negative bacteria. Seventy-five strains represented 21 of the 26 taxa included in the Vitek 2 NH database and 25 strains represented related species not included in the database. Of the 100 strains, 31 were the type strains of the species. Vitek 2 NH identification...... results: 48 of 75 database strains were correctly identified, 11 strains gave `low discrimination´, seven strains were unidentified, and nine strains were misidentified. Identification of 25 non-database strains resulted in 14 strains incorrectly identified as belonging to species in the database. Partial...

Probing the Penetration of Antimicrobial Polymyxin Lipopeptides into Gram-Negative Bacteria

Science.gov (United States)

2015-01-01

The dry antibiotic development pipeline coupled with the emergence of multidrug resistant Gram-negative ‘superbugs’ has driven the revival of the polymyxin lipopeptide antibiotics. Polymyxin resistance implies a total lack of antibiotics for the treatment of life-threatening infections. The lack of molecular imaging probes that possess native polymyxin-like antibacterial activity is a barrier to understanding the resistance mechanisms and the development of a new generation of polymyxin lipopeptides. Here we report the regioselective modification of the polymyxin B core scaffold at the N-terminus with the dansyl fluorophore to generate an active probe that mimics polymyxin B pharmacologically. Time-lapse laser scanning confocal microscopy imaging of the penetration of probe (1) into Gram-negative bacterial cells revealed that the probe initially accumulates in the outer membrane and subsequently penetrates into the inner membrane and finally the cytoplasm. The implementation of this polymyxin-mimetic probe will advance the development of platforms for the discovery of novel polymyxin lipopeptides with efficacy against polymyxin-resistant strains. PMID:24635310

Mucilaginibacter pedocola sp. nov., isolated from a heavy-metal-contaminated paddy field.

Science.gov (United States)

Tang, Jingwei; Huang, Jing; Qiao, Zixu; Wang, Rui; Wang, Gejiao

2016-10-01

Strain TBZ30T was isolated from soil of a heavy-metal-contaminated paddy field. Cells of strain TBZ30T were Gram-staining-negative, rod-shaped, non-motile and non-spore-forming. The isolate was strictly aerobic, pink-pigmented, catalase- and oxidase-positive and produced exopolysaccharides. On the basis of 16S rRNA gene phylogeny, strain TBZ30T belonged to the genus Mucilaginibacter and appeared most closely related to Mucilaginibacter gynuensis YC7003T (95.8 %), Mucilaginibacter litoreus BR-18T (95.4 %) and Mucilaginibacter mallensis MP1X4T (95.4 %). Strain TBZ30T contained menaquinone-7 as the only ubiquinone. The main cellular fatty acids included summed feature 3 (C16 : 1ω7c and/or iso-C15 : 0 2-OH), iso-C15 : 0, C16 : 0, iso-C17 : 0 3-OH and C16 : 1ω5c. The polar lipids were phosphatidylethanolamine, an unidentified phospholipid, two unidentified aminophospholipids, four unidentified aminolipids, three unidentified lipids and two unidentified glycolipids. The genomic DNA G+C content was 49.0 mol%. On the basis of polyphasic taxonomy analyses, strain TBZ30T represents a novel species of the genus Mucilaginibacter, for which the name Mucilaginibacter pedocola sp. nov. is proposed. The type strain is TBZ30T (=KCTC 42833T=CCTCC AB 2015301T).

Expression levels of matrix metalloproteinase-9 and gram-negative bacteria in symptomatic and asymptomatic periapical lesions.

Science.gov (United States)

Ahmed, Geraldine M; El-Baz, Alaa A; Hashem, Ahmed Abdel Rahman; Shalaan, Abeer K

2013-04-01

The aim of this study was to test the hypothesis that the expression of matrix metalloproteinase (MMP)-9 is significantly elevated in patients with symptomatic apical periodontitis and to correlate this with the detected amount of gram-negative bacteria. Twenty-six patients with periapical lesions involving at least 2 teeth were included in this study. The patients were divided into 2 groups: the symptomatic (SYM) group included 13 patients expressing pain with periapical lesions, and the asymptomatic (ASYM) group included 13 patients expressing no pain. Root canal treatment was performed followed by endodontic surgery and periapical lesion collection. Periapical lesions were serially cut into 4-μ sections. Some sections were processed for histologic examination using hematoxylin-eosin stain. Other sections were processed for immunohistochemical examination. For MMP-9, the area fraction of the positive cells was measured, and the percentage of the MMP-9-immunopositive area to the total area of the microscopic field was calculated. For gram-negative stain cells, the number of cells showing the pink-red color was counted per microscopic field. The Student's t test was used to compare the SYM and ASYM groups. The Pearson correlation coefficient was used to determine a significant correlation between the number of cells and the MMP-9 level. The significance level was set at P ≤ .05. The SYM group showed a statistically significantly higher mean number of gram-negative cells (P = .001) and MMP-9 area percent (P < .001) than the ASYM group. There was a statistically significant positive (r = .927) correlation between the number of gram-negative cells and the MMP-9 area percent (P< .001). There is good evidence to suspect a significant role of gram-negative bacteria and MMP-9 in symptomatic periapical lesions. Copyright © 2013 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

A simple identification method for spore-forming bacteria showing high resistance against γ-rays

International Nuclear Information System (INIS)

Koshikawa, Tomihiko; Sone, Koji; Kobayashi, Toshikazu

1993-01-01

A simple identification method was developed for spore-forming bacteria which are highly resistant against γ-rays. Among 23 species of Bacillus studied, the spores of Bacillus megaterium, B. cereus, B. thuringiensis, B. pumilus and B. aneurinolyticus showed high resistance against γ-rays as compared with other spores of Bacillus species. Combination of the seven kinds of biochemical tests, namely, the citrate utilization test, nitrate reduction test, starch hydrolysis test, Voges-Proskauer reaction test, gelatine hydrolysis test, mannitol utilization test and xylose utilization test showed a characteristic pattern for each species of Bacillus. The combination pattern of each the above tests with a few supplementary test, if necessary, was useful to identify Bacillus species showing high radiation resistance against γ-rays. The method is specific for B. megaterium, B. thuringiensis and B. pumilus, and highly selective for B. aneurinolyticus and B. cereus. (author)

[Left-sided endocarditis due to gram-negative bacilli: epidemiology and clinical characteristics].

Science.gov (United States)

Noureddine, Mariam; de la Torre, Javier; Ivanova, Radka; Martínez, Francisco José; Lomas, Jose María; Plata, Antonio; Gálvez, Juan; Reguera, Jose María; Ruiz, Josefa; Hidalgo, Carmen; Luque, Rafael; García-López, María Victoria; de Alarcón, Arístides

2011-04-01

The aim of this study is to describe the epidemiological, clinical characteristics, and outcome of patients with left-side endocarditis caused by gram-negative bacteria. Prospective multicenter study of left-sided infective endocarditis reported in the Andalusian Cohort for the Study of Cardiovascular Infections between 1984 and 2008. Among the 961 endocarditis, 24 (2.5%) were caused by gram-negative bacilli. The most common pathogens were Escherichia coli, Pseudomonas aeruginosa and Salmonella enterica. Native valves (85.7%) were mainly affected, most of them with previous valve damage (57%). Comorbidity was greater (90% vs 39%; P=.05) than in endocarditis due to other microorganism, the most frequent being, diabetes, hepatic cirrhosis and neoplasm. A previous manipulation was found in 47.6% of the cases, and 37% were considered hospital-acquired. Renal failure (41%), central nervous system involvement (33%) and ventricular dysfunction (45%) were the most frequent complications. Five cases (21%) required cardiac surgery, mostly due to ventricular dysfunction. More than 50% of cases were treated with aminoglycosides, but this did not lead to a better outcome or prognosis. Mortality (10 patients) was higher than that reported with other microorganisms (41% vs 35%; P=.05). Left-sided endocarditis due to gram-negative bacilli is a rare disease, which affects patients with major morbidities and often with a previous history of hospital manipulations. Cardiac, neurological and renal complications are frequent and associated with a high mortality. The association of aminoglycosides in the antimicrobial treatment did not involve a better outcome or prognosis. Copyright © 2010 Elsevier España, S.L. All rights reserved.

ANTIBIOTIC RESISTANCE SPECTRUM OF NON FERMENTING GRAM NEGATIVE BACILLI ISOLATED IN THE ORTHOPEDIC TRAUMATOLOGY CLINIC OF "SF. SPIRIDON" CLINICAL EMERGENCY HOSPITAL IAŞI.

Science.gov (United States)

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

2015-01-01

The retro-prospective analysis of antibiotic sensitivity of non-fermenting gram negative bacilli strains circulating in the Orthopedics-Traumatology Clinic from "Sf. Spiridon" Emergency Clinical Hospital in view of determining the trend of the resistance phenomenon and indicating the most useful treatment for the infections caused by these strains. The retrospective component was conducted from 01.01.2003 to 31.12.2012, and the result of the diffusimetric antibiograms was taken from the hospital's informatics system; the prospective component of the study involved the collection of pathological products from the patients admitted during January-December 2013, who showed clinical suspicion of infection, in compliance with the general collection norms for the products destined for the bacteriological exam. From the total 167 strains of Pseudomonas aeruginosa isolated and identified from the patients, 48 (28.74%) were sensitive to at least one antibiotic from each tested class, 29 (17.39%) were resistant to a single antibiotic and the rest of 90 (53.89%) showed multiple resistance. We noticed a statistically significant difference between the number of strains sensitive to at least one antibiotic from each tested class and those with multiple resistance (p < 0.05). For the strains of Acinetobacter baumanii combined resistance was identified for 121 (87.04%), out of which 55 (39.56%) were resistant to two classes of antibiotics and the other (47.48%) to all three classes. The most frequently met was the association of resistance to quinolones and aminoglycosides, namely for a number of 49 strains (35.25%); only 3.59% of them were simultaneously sensitive to the three classes of antibiotics. The already high percentages and the rising trends of antibiotic resistance of non-fermenting gram-negative bacteria described in this study confirm the continuous decrease of the efficiency of antimicrobial agents and underline the necessity of a global strategy which aims at all

Calculation model of non-linear dynamic deformation of composite multiphase rods

Directory of Open Access Journals (Sweden)

Mishchenko Andrey Viktorovich

2014-05-01

Full Text Available The method of formulating non-linear physical equations for multiphase rods is suggested in the article. Composite multiphase rods possess various structures, include shear, polar, radial and axial inhomogeneity. The Timoshenko’s hypothesis with the large rotation angles is used. The method is based on the approximation of longitudinal normal stress low by basic functions expansions regarding the linear viscosity low. The shear stresses are calculated with the equilibrium equation using the subsidiary function of the longitudinal shift force. The system of differential equations connecting the internal forces and temperature with abstract deformations are offered by the basic functions. The application of power functions with arbitrary index allows presenting the compact form equations. The functional coefficients in this system are the highest order rigidity characteristics. The whole multiphase cross-section rigidity characteristics are offered the sums of the rigidity characteristics of the same phases individually. The obtained system allows formulating the well-known particular cases. Among them: hard plasticity and linear elastic deformation, different module deformation and quadratic Gerstner’s low elastic deformation. The reform of differential equations system to the quasilinear is suggested. This system contains the secant variable rigidity characteristics depending on abstract deformations. This system includes the sum of the same uniform blocks of different order. The rods phases defined the various set of uniform blocks phase materials. The integration of dynamic, kinematic and physical equations taking into account initial and edge condition defines the full dynamical multiphase rods problem. The quasilinear physical equations allow getting the variable flexibility matrix of multiphase rod and rods system.

Shape-dependent bactericidal activity of copper oxide nanoparticle mediated by DNA and membrane damage

International Nuclear Information System (INIS)

Laha, Dipranjan; Pramanik, Arindam; Laskar, Aparna; Jana, Madhurya; Pramanik, Panchanan; Karmakar, Parimal

2014-01-01

Highlights: • Spherical and sheet shaped copper oxide nanoparticles were synthesized. • Physical characterizations of these nanoparticles were done by TEM, DLS, XRD, FTIR. • They showed shape dependent antibacterial activity on different bacterial strain. • They induced both membrane damage and ROS mediated DNA damage in bacteria. - Abstract: In this work, we synthesized spherical and sheet shaped copper oxide nanoparticles and their physical characterizations were done by the X-ray diffraction, fourier transform infrared spectroscopy, transmission electron microscopy and dynamic light scattering. The antibacterial activity of these nanoparticles was determined on both gram positive and gram negative bacterial. Spherical shaped copper oxide nanoparticles showed more antibacterial property on gram positive bacteria where as sheet shaped copper oxide nanoparticles are more active on gram negative bacteria. We also demonstrated that copper oxide nanoparticles produced reactive oxygen species in both gram negative and gram positive bacteria. Furthermore, they induced membrane damage as determined by atomic force microscopy and scanning electron microscopy. Thus production of and membrane damage are major mechanisms of the bactericidal activity of these copper oxide nanoparticles. Finally it was concluded that antibacterial activity of nanoparticles depend on physicochemical properties of copper oxide nanoparticles and bacterial strain

Shape-dependent bactericidal activity of copper oxide nanoparticle mediated by DNA and membrane damage

Energy Technology Data Exchange (ETDEWEB)

Laha, Dipranjan; Pramanik, Arindam [Department of Life Science and Biotechnology, Jadavpur University, 188, Raja S C Mallick Road, Kolkata 700032 (India); Laskar, Aparna [CSIR-Indian Institute of Chemical Biology, Kolkata 700032 (India); Jana, Madhurya [Department of Life Science and Biotechnology, Jadavpur University, 188, Raja S C Mallick Road, Kolkata 700032 (India); Pramanik, Panchanan [Department of Chemistry, Indian Institute of Technology, Kharagpur 721302 (India); Karmakar, Parimal, E-mail: pkarmakar_28@yahoo.co.in [Department of Life Science and Biotechnology, Jadavpur University, 188, Raja S C Mallick Road, Kolkata 700032 (India)

2014-11-15

Highlights: • Spherical and sheet shaped copper oxide nanoparticles were synthesized. • Physical characterizations of these nanoparticles were done by TEM, DLS, XRD, FTIR. • They showed shape dependent antibacterial activity on different bacterial strain. • They induced both membrane damage and ROS mediated DNA damage in bacteria. - Abstract: In this work, we synthesized spherical and sheet shaped copper oxide nanoparticles and their physical characterizations were done by the X-ray diffraction, fourier transform infrared spectroscopy, transmission electron microscopy and dynamic light scattering. The antibacterial activity of these nanoparticles was determined on both gram positive and gram negative bacterial. Spherical shaped copper oxide nanoparticles showed more antibacterial property on gram positive bacteria where as sheet shaped copper oxide nanoparticles are more active on gram negative bacteria. We also demonstrated that copper oxide nanoparticles produced reactive oxygen species in both gram negative and gram positive bacteria. Furthermore, they induced membrane damage as determined by atomic force microscopy and scanning electron microscopy. Thus production of and membrane damage are major mechanisms of the bactericidal activity of these copper oxide nanoparticles. Finally it was concluded that antibacterial activity of nanoparticles depend on physicochemical properties of copper oxide nanoparticles and bacterial strain.

Isolation and purification of membrane-bound cytochrome c from ...

African Journals Online (AJOL)

Administrator

2007-05-02

ferrochrome and redox spectra showed the presence of heme-c. Key words: Cytochrome c, respiratory chain and Proteus mirabilis. INTRODUCTION. Proteus mirabilis is facultative anaerobic, rod-shaped, gram negative bacterium.

Nosocomial bloodstream infections in a Turkish university hospital: study of Gram-negative bacilli and their sensitivity patterns.

Science.gov (United States)

Köseoğlu , O; Kocagöz, S; Gür, D; Akova, M

2001-06-01

Treatment of nosocomial bacteraemia is usually governed by the surveillance results of the particular unit. Such results are especially important when antimicrobial resistance rates are high. Multiresistant isolates including Gram-negatives producing extended-spectrum beta-lactamases have been frequently reported in tertiary care units in Turkey. In this study, antimicrobial susceptibilities of Gram-negative blood isolates (n=348) were determined by microbroth dilution tests. The results showed carbapenems (meropenem and imipenem) to be uniformly more potent in vitro than any other drug against the Enterobacteriaceae. Quinolone antibiotics were more active in vitro than aminoglycosides against a range of bacteria. Gram-negative bloodstream isolates were highly resistant to many antimicrobial agents in the hospital. In order to prevent hospital infection and antimicrobial resistance, surveillance of aetiological agents must be performed regularly.

Fuel rod fixing system

International Nuclear Information System (INIS)

Christiansen, D.W.

1982-01-01

This is a reusable system for fixing a nuclear reactor fuel rod to a support. An interlock cap is fixed to the fuel rod and an interlock strip is fixed to the support. The interlock cap has two opposed fingers, which are shaped so that a base is formed with a body part. The interlock strip has an extension, which is shaped so that this is rigidly fixed to the body part of the base. The fingers of the interlock cap are elastic in bending. To fix it, the interlock cap is pushed longitudinally on to the interlock strip, which causes the extension to bend the fingers open in order to engage with the body part of the base. To remove it, the procedure is reversed. (orig.) [de

Proposal of Mucilaginibacter galii sp. nov. isolated from leaves of Galium album.

Science.gov (United States)

Aydogan, Ebru L; Busse, Hans-Jürgen; Moser, Gerald; Müller, Christoph; Kämpfer, Peter; Glaeser, Stefanie P

2017-05-01

A pale-pink-pigmented, Gram-stain-negative, rod-shaped, non-spore-forming bacterial strain, PP-F2F-G47T, was isolated from the phyllosphere of the herbaceous plant Galium album. Phylogenetic analysis based on the nearly full-length 16S rRNA gene sequence revealed highest sequence similarity to the type strains of Mucilaginibacter daejeonensis (96.2 %), Mucilaginibacter dorajii (95.7 %) and Mucilaginibacter phyllosphaerae (95.5 %). 16S rRNA gene sequence similarities to all other type strains were below 95.5 %. The predominant cellular fatty acids of the strain were C16 : 1ω7c/iso-C15 : 0 2-OH (measured as summed feature 3) and iso-C15 : 0. The major compound in the polyamine pattern was sym-homospermidine and major quinone was menaquinone MK-7. The polar lipid profile was composed of phosphatidylethanolamine and several unidentified aminolipipids, phospholipids, aminophospholipids and lipids without a functional group. A sphingophospholipid could not be detected but a ninhydrin-positive alkaline-stable lipid was visible. The diagnostic diamino acid of the peptidoglycan was meso-diaminopimelic acid. Based on phylogenetic, chemotaxonomic and phenotypic analyses a novel species is proposed, Mucilaginibacter galii sp. nov., with PP-F2F-G47T (=CCM 8711T=CIP 111182T=LMG 29767T) as the type strain.

Rapid and reliable identification of Gram-negative bacteria and Gram-positive cocci by deposition of bacteria harvested from blood cultures onto the MALDI-TOF plate.

Science.gov (United States)

Barnini, Simona; Ghelardi, Emilia; Brucculeri, Veronica; Morici, Paola; Lupetti, Antonella

2015-06-18

Rapid identification of the causative agent(s) of bloodstream infections using the matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) methodology can lead to increased empirical antimicrobial therapy appropriateness. Herein, we aimed at establishing an easier and simpler method, further referred to as the direct method, using bacteria harvested by serum separator tubes from positive blood cultures and placed onto the polished steel target plate for rapid identification by MALDI-TOF. The results by the direct method were compared with those obtained by MALDI-TOF on bacteria isolated on solid media. Identification of Gram-negative bacilli was 100 % concordant using the direct method or MALDI-TOF on isolated bacteria (96 % with score > 2.0). These two methods were 90 % concordant on Gram-positive cocci (32 % with score > 2.0). Identification by the SepsiTyper method of Gram-positive cocci gave concordant results with MALDI-TOF on isolated bacteria in 87 % of cases (37 % with score > 2.0). The direct method herein developed allows rapid identification (within 30 min) of Gram-negative bacteria and Gram-positive cocci from positive blood cultures and can be used to rapidly report reliable and accurate results, without requiring skilled personnel or the use of expensive kits.

Prevalence and risk factors for CTX-M gram-negative bacteria in hospitalized patients at a tertiary care hospital in Kilimanjaro, Tanzania

DEFF Research Database (Denmark)

Sonda, Tolbert; Kumburu, Happiness; van Zwetselaar, Marco

2018-01-01

Emergence and spread of extended spectrum beta-lactamase (ESBL)-producing gram-negative bacteria, mainly due to CTX-M, is a major global public health problem. Patients infected with ESBL-producing gram-negative bacteria have an increased risk of treatment failure and death. We investigated...... 2015 were fully genome sequenced. The prevalence of ESBL-producing gram-negative bacteria was determined based on the presence of blaCTX-M. The odds ratio (OR) and risk factors for ESBL-producing gram-negative bacteria due to CTX-M were assessed using logistic regression models. The overall CTX......-M prevalence (95% CI) was 13.6% (10.1–18.1). Adjusted for other factors, the OR of CTX-M gram-negative bacteria for patients previously hospitalized was 0.26 (0.08–0.88), p = 0.031; the OR for patients currently on antibiotics was 4.02 (1.29–12.58), p = 0.017; the OR for patients currently on ceftriaxone was 0...

Evaluation of surface contamination of bacteria in various dental clinics with special reference to obligate and facultative anaerobic spore bearing bacilli

Directory of Open Access Journals (Sweden)

Kannan I, Jessica Yolanda Jeevitha, Sambandam Cecilia, Jayalakshmi M, Premavathy RK and Shantha S

2014-07-01

Full Text Available Introduction: The occupational health and safety is an important prerequisite in dental clinic setup for well being of both the doctor and patient. Both the patient and dentist are always at the risk of infections. Aim and objectives: There is no proper literature on the survey of bacterial spores, especially of Clostridium species in dental clinics. Hence an attempt has been made in the present pilot study to evaluate the surface contamination with special reference to bacterial spores. Materials and methods: Various dental clinics from Chennai city, India were selected for the present study. Samples were collected from two clinics each from endodontic, prosthodontic, orthodontic, and periodontic. In each clinic important places were selected for sampling. The samples were collected in the form of swabs. The swabs thus obtained were inoculated into Robertson Cooked Meat Medium and was incubated in anaerobic condition at 370C for 7 days. Each day the tubes were examined for turbidity and colour change and were noted. At the end of 7th day the smear was prepared from each tube and gram staining was performed. The gram stained slides were examined microscopically for the presence of spore bearing bacilli especially with special reference to terminal spore bearing bacilli. Results and conclusion: From the present study it is clear that the dental clinics invariably posses a lot of aerobic and anaerobic spores irrespective of stringent disinfection procedures. Hence it is mandatory for the dental clinics to undergo periodical microbiological surveillance and to take proper steps in the control of bacterial spores.

High resistance rate against 15 different antibiotics in aerobic gram-negative bacteria isolates of cardiology intensive care unit patients

Directory of Open Access Journals (Sweden)

Küçükates E

2002-01-01

Full Text Available Aerobic gram negative bacteria were isolated and examined microbiologically from various clinical samples of 602 patients hospitalized between January 1997 and December 2000 in surgical and coronary intensive care units (ICUs. A total of 827 isolates were obtained from 602 patients. The majority of microorganisms were isolated from the respiratory tract (50.3% and blood (39.9%. Pseudomonas spp. were the most frequently isolated gram negative species (32.7%, followed by Acinetobacter spp. (24.0% and Klebsiella pneumoniae (19.4%. High resistance rates to all antibiotics studied were observed. Imipenem and meropenem were the most effective antibiotics against gram negatives.

Effect of silver/copper and copper oxide nanoparticle powder on growth of Gram-negative and Gram-positive bacteria and their toxicity against the normal human dermal fibroblasts

International Nuclear Information System (INIS)

Peszke, Jerzy; Nowak, Anna; Szade, Jacek; Szurko, Agnieszka; Zygadło, Dorota; Michałowska, Marlena; Krzyściak, Paweł; Zygoń, Patrycja; Ratuszna, Alicja; Ostafin, Marek M.

2016-01-01

Engineered nanomaterials, especially metallic nanoparticles, are the most popular system applied in daily life products. The study of their biological and toxicity properties seems to be indispensable. In this paper, we present results of biological activity of Ag/Cu nanoparticles. These nanoparticles show more promising killing/inhibiting properties on Gram-negative bacteria than for Gram-positive ones. The Gram-negative bacteria show strong effect already at the concentration of 1 ppm after 15 min of incubation. Moreover, in vitro tests of toxicity made on normal human dermal fibroblast cultures showed that after 72 h of incubation with Ag/Cu nanoparticles, they are less toxic then Cu 2 O/CuO nanoparticles.

Effect of silver/copper and copper oxide nanoparticle powder on growth of Gram-negative and Gram-positive bacteria and their toxicity against the normal human dermal fibroblasts

Energy Technology Data Exchange (ETDEWEB)

Peszke, Jerzy; Nowak, Anna, E-mail: ana.maria.nowak@gmail.com; Szade, Jacek; Szurko, Agnieszka; Zygadło, Dorota; Michałowska, Marlena [University of Silesia, A. Chelkowski Institute of Physics (Poland); Krzyściak, Paweł [Jagiellonian University Medical College, Department of Mycology Chair of Microbiology (Poland); Zygoń, Patrycja [Czestochowa University of Technology, Institute of Materials Engineering (Poland); Ratuszna, Alicja [University of Silesia, A. Chelkowski Institute of Physics (Poland); Ostafin, Marek M. [Department of Microbiology University of Agriculture (Poland)

2016-12-15

Engineered nanomaterials, especially metallic nanoparticles, are the most popular system applied in daily life products. The study of their biological and toxicity properties seems to be indispensable. In this paper, we present results of biological activity of Ag/Cu nanoparticles. These nanoparticles show more promising killing/inhibiting properties on Gram-negative bacteria than for Gram-positive ones. The Gram-negative bacteria show strong effect already at the concentration of 1 ppm after 15 min of incubation. Moreover, in vitro tests of toxicity made on normal human dermal fibroblast cultures showed that after 72 h of incubation with Ag/Cu nanoparticles, they are less toxic then Cu{sub 2}O/CuO nanoparticles.

An unusual class of anthracyclines potentiate Gram-positive antibiotics in intrinsically resistant Gram-negative bacteria

Science.gov (United States)

Cox, Georgina; Koteva, Kalinka; Wright, Gerard D.

2014-01-01

Objectives An orthogonal approach taken towards novel antibacterial drug discovery involves the identification of small molecules that potentiate or enhance the activity of existing antibacterial agents. This study aimed to identify natural-product rifampicin adjuvants in the intrinsically resistant organism Escherichia coli. Methods E. coli BW25113 was screened against 1120 actinomycete fermentation extracts in the presence of subinhibitory (2 mg/L) concentrations of rifampicin. The active molecule exhibiting the greatest rifampicin potentiation was isolated using activity-guided methods and identified using mass and NMR spectroscopy. Susceptibility testing and biochemical assays were used to determine the mechanism of antibiotic potentiation. Results The anthracycline Antibiotic 301A1 was isolated from the fermentation broth of a strain of Streptomyces (WAC450); the molecule was shown to be highly synergistic with rifampicin (fractional inhibitory concentration index = 0.156) and moderately synergistic with linezolid (FIC index = 0.25) in both E. coli and Acinetobacter baumannii. Activity was associated with inhibition of efflux and the synergistic phenotype was lost when tested against E. coli harbouring mutations within the rpoB gene. Structure–activity relationship studies revealed that other anthracyclines do not synergize with rifampicin and removal of the sugar moiety of Antibiotic 301A1 abolishes activity. Conclusions Screening only a subsection of our natural product library identified a small-molecule antibiotic adjuvant capable of sensitizing Gram-negative bacteria to antibiotics to which they are ordinarily intrinsically resistant. This result demonstrates the great potential of this approach in expanding antibiotic effectiveness in the face of the growing challenge of resistance in Gram-negatives. PMID:24627312

Pink-pigmented non-fermentative gram-negative rods associated with human infections: a clinical and diagnostic challenge.

Science.gov (United States)

Hogue, R; Graves, M; Moler, S; Janda, J M

2007-06-01

Over the past several decades, the appearance of pink-pigmented bacteria in clinical specimens has gone from being a microbiologic curiosity in the clinical laboratory to the recognition of these aerobic microorganisms as etiologic agents of human disease, most notably bloodstream infections. Advances in the fields of molecular taxonomy and phylogenetics indicate that at least four distinct genera and eight different species are associated with clinical infections in susceptible patient populations. However, these bacteria are slow growing and present multiple diagnostic challenges to the microbiology laboratory including culture, isolation, and identification to species rank. This article provides a current review of these unusual non-fermentative chromogenic bacteria including their disease spectrum, taxonomy, and laboratory identification. The review also highlights the pitfalls or shortcomings we currently have in our knowledge of these microbes and their disease-producing capabilities.

Rapid and accurate control rod calibration measurement and analysis

International Nuclear Information System (INIS)

Nelson, George W.; Doane, Harry J.

1990-01-01

In order to reduce the time needed to perform control rod calibrations and improve the accuracy of the results, a technique for a measurement, analysis, and tabulation of integral rod worths has been developed. A single series of critical rod positions are determined at constant low power to reduce the waiting time between positive period measurements and still assure true stable reactor period data. Reactivity values from positive period measurements and control rod drop measurements are used as input data for a non-linear fit to the expected control rod integral worth shape. With this method, two control rods can be calibrated in about two hours, and integral and differential calibration tables for operator use are printed almost immediately. Listings of the BASIC computer programs for the non-linear fitting and calibration table preparation are provided. (author)

Sensitivity studies for 3-D rod ejection analyses on axial power shape

Energy Technology Data Exchange (ETDEWEB)

Park, Min-Ho; Park, Jin-Woo; Park, Guen-Tae; Ryu, Seok-Hee; Um, Kil-Sup; Lee, Jae-Il [KEPCO NF, Daejeon (Korea, Republic of)

2015-10-15

The current safety analysis methodology using the point kinetics model combined with numerous conservative assumptions result in unrealistic prediction of the transient behavior wasting huge margin for safety analyses while the safety regulation criteria for the reactivity initiated accident are going strict. To deal with this, KNF is developing a 3-D rod ejection analysis methodology using the multi-dimensional code coupling system CHASER. The CHASER system couples three-dimensional core neutron kinetics code ASTRA, sub-channel analysis code THALES, and fuel performance analysis code FROST using message passing interface (MPI). A sensitivity study for 3-D rod ejection analysis on axial power shape (APS) is carried out to survey the tendency of safety parameters by power distributions and to build up a realistic safety analysis methodology while maintaining conservatism. The currently developing 3-D rod ejection analysis methodology using the multi-dimensional core transient analysis code system, CHASER was shown to reasonably reflect the conservative assumptions by tuning up kinetic parameters.

Improvement of uniformity of the negative ion beams by tent-shaped magnetic field in the JT-60 negative ion source

International Nuclear Information System (INIS)

Yoshida, Masafumi; Hanada, Masaya; Kojima, Atsushi; Kashiwagi, Mieko; Akino, Noboru; Endo, Yasuei; Komata, Masao; Mogaki, Kazuhiko; Nemoto, Shuji; Ohzeki, Masahiro; Seki, Norikazu; Sasaki, Shunichi; Shimizu, Tatsuo; Terunuma, Yuto; Grisham, Larry R.

2014-01-01

Non-uniformity of the negative ion beams in the JT-60 negative ion source with the world-largest ion extraction area was improved by modifying the magnetic filter in the source from the plasma grid (PG) filter to a tent-shaped filter. The magnetic design via electron trajectory calculation showed that the tent-shaped filter was expected to suppress the localization of the primary electrons emitted from the filaments and created uniform plasma with positive ions and atoms of the parent particles for the negative ions. By modifying the magnetic filter to the tent-shaped filter, the uniformity defined as the deviation from the averaged beam intensity was reduced from 14% of the PG filter to ∼10% without a reduction of the negative ion production

Lipopolysaccharide biogenesis and transport at the outer membrane of Gram-negative bacteria.

Science.gov (United States)

Sperandeo, Paola; Martorana, Alessandra M; Polissi, Alessandra

2017-11-01

The outer membrane (OM) of Gram-negative bacteria is an asymmetric lipid bilayer containing a unique glycolipid, lipopolysaccharide (LPS) in its outer leaflet. LPS molecules confer to the OM peculiar permeability barrier properties enabling Gram-negative bacteria to exclude many toxic compounds, including clinically useful antibiotics, and to survive harsh environments. Transport of LPS poses several problems to the cells due to the amphipatic nature of this molecule. In this review we summarize the current knowledge on the LPS transport machinery, discuss the challenges associated with this process and present the solutions that bacterial cells have evolved to address the problem of LPS transport and assembly at the cell surface. Finally, we discuss how knowledge on LPS biogenesis can be translated for the development of novel antimicrobial therapies. This article is part of a Special Issue entitled: Bacterial Lipids edited by Russell E. Bishop. Copyright © 2016. Published by Elsevier B.V.

Electron Beam Irradiation Dose Dependently Damages the Bacillus Spore Coat and Spore Membrane

Directory of Open Access Journals (Sweden)

S. E. Fiester

2012-01-01

Full Text Available Effective control of spore-forming bacilli begs suitable physical or chemical methods. While many spore inactivation techniques have been proven effective, electron beam (EB irradiation has been frequently chosen to eradicate Bacillus spores. Despite its widespread use, there are limited data evaluating the effects of EB irradiation on Bacillus spores. To study this, B. atrophaeus spores were purified, suspended in sterile, distilled water, and irradiated with EB (up to 20 kGy. Irradiated spores were found (1 to contain structural damage as observed by electron microscopy, (2 to have spilled cytoplasmic contents as measured by spectroscopy, (3 to have reduced membrane integrity as determined by fluorescence cytometry, and (4 to have fragmented genomic DNA as measured by gel electrophoresis, all in a dose-dependent manner. Additionally, cytometry data reveal decreased spore size, increased surface alterations, and increased uptake of propidium iodide, with increasing EB dose, suggesting spore coat alterations with membrane damage, prior to loss of spore viability. The present study suggests that EB irradiation of spores in water results in substantial structural damage of the spore coat and inner membrane, and that, along with DNA fragmentation, results in dose-dependent spore inactivation.

Pedobacter humicola sp. nov., a member of the genus Pedobacter isolated from soil.

Science.gov (United States)

Dahal, Ram Hari; Kim, Jaisoo

2016-06-01

An aerobic, Gram-stain-negative, oxidase-negative, catalase-positive, non-motile, non-spore-forming, rod-shaped, light pink-pigmented bacterium, designated strain R135T, was isolated from soil in Hwaseong, South Korea. Flexirubin-type pigments were absent. Phylogenetic analysis based on the 16S rRNA gene sequence revealed that strain R135T formed a lineage within the family Sphingobacteriaceae of the phylum Bacteroidetes. It was distinct from various species of the genus Pedobacter, including P. terrae DS-57T (98.13 % sequence similarity), P. alluvionis NWER-II11T (97.76 %), P. suwonensis 15-52T (97.71 %), P. kyungheensis KACC 16221T (97.37 %), P. roseus CG-GP80T (97.24 %), P. soli 15-51T (97.23 %) and P. sandarakinus DS-27T (97.09 %). The major isoprenoid quinone was menaquinone-7 (MK-7), and the major polar lipid was phosphatidylethanolamine. The major cellular fatty acids were summed feature 3 (C16 : 1ω7c and/or C16 : 1ω6c), iso-C15 : 0, iso-C17 : 0 3-OH and C16 : 0. The DNA G+C content of strain R135T was 40.4 mol%. Levels of DNA-DNA hybridization similarities between strain R135Tand other members of the genus Pedobacter ranged from 25 % to 43 %. On the basis of phenotypic, genotypic and phylogenetic analysis, strain R135T represents a novel species of the genus Pedobacter, for which the name Pedobacter humicola sp. nov. is proposed. The type strain is R135T (=KEMB 9005-332T=KACC 18452T=JCM 31010T).

Microvirga soli sp. nov., an alphaproteobacterium isolated from soil.

Science.gov (United States)

Dahal, Ram Hari; Kim, Jaisoo

2017-01-01

An aerobic, Gram-stain-negative, catalase-positive and oxidase-negative, non-motile, non-spore-forming, rod-shaped, pink-pigmented bacterium designated strain R491T was isolated from soil. Flexirubin-type pigments were absent. Phylogenetic analysis based on 16S rRNA gene sequences revealed that strain R491T formed a lineage within the family Methylobacteriaceae of the phylum Proteobacteria that was distinct from various species of the genus Microvirga, including Microvirgaaerilata 5420S-16T (97.83 % 16S rRNA gene sequence similarity), Microvirga zambiensis WSM3693T (97.76 %), Microvirga flocculans ATCC BAA-817T (97.41 %), and Microvirga lupini Lut6T, Microvirga subterranea DSM 14364T, Microvirga vignae BR3299T, and Microvirga guangxiensis 25BT (96.99 %). The major polar lipids of strain R491T were phosphatidylcholine, phosphatidylglycerol and phosphatidylethanolamine. The major cellular fatty acids were summed feature 8 (C18 : 1ω7c and/or C18 : 1ω6c; 71.2 %), C16 : 0 (12.0 %), summed feature 3 (C16 : 1ω7c and/or C16 : 1ω6c; 4.7 %), and C18 : 0 (4.2 %). The DNA G+C content of strain R491T was 61.8 mol%. DNA-DNA hybridization values between strain R491T and other members of the genus Microvirga ranged from 27 to 57 %. On the basis of phenotypic, genotypic and phylogenetic analyses, strain R491T represents a novel species of the genus Microvirga, for which the name Microvirga soli sp. nov. is proposed. The type strain is R491T (=KEMB 9005-408T=KACC 18969T=NBRC 112417T).

Tsukamurella spongiae sp. nov., a novel actinomycete isolated from a deep-water marine sponge.

Science.gov (United States)

Olson, Julie B; Harmody, Dedra K; Bej, Asim K; McCarthy, Peter J

2007-07-01

A Gram-positive, rod-shaped, non-spore-forming bacterium (strain K362(T)) was isolated from a deep-water marine sponge collected off the coast of Curaçao in the Netherlands Antilles. On the basis of 16S rRNA gene sequence similarities, strain K362(T) was shown to belong to the genus Tsukamurella, being most closely related to Tsukamurella pulmonis (99.2 %), Tsukamurella tyrosinosolvens (98.9 %), Tsukamurella strandjordii (98.8 %), Tsukamurella pseudospumae (98.8 %) and Tsukamurella spumae (98.8 %). A combination of the substrate utilization patterns, the fatty acid and mycolic acid profiles and the DNA-DNA hybridization results supported the affiliation of strain K362(T) to the genus Tsukamurella and enabled the genotypic and phenotypic differentiation of strain K362(T) from the seven recognized Tsukamurella species. Strain K362(T) therefore represents a novel species of the genus Tsukamurella, for which the name Tsukamurella spongiae sp. nov. is proposed. The type strain is K362(T) (=DSM 44990(T)=NRRL B-24467(T)).

Preparation and characterization of the rod-shaped stibnite

Energy Technology Data Exchange (ETDEWEB)

Ouni, B., E-mail: bachir.ouni@laposte.net [Unité de Physique des Dispositifs a Semi-conducteurs, Faculté des Sciences deTunis, Tunis El Manar University, 2092 Tunis (Tunisia); Zouini, M. [Laboratoire de Photovoltaïque, Centre de Recherches et des Technologies de l' Energie, Technopôle de Borj-Cédria, BP 95, Hammam-Lif 2050 (Tunisia); Lakhdar, M. Haj; Larbi, T. [Unité de Physique des Dispositifs a Semi-conducteurs, Faculté des Sciences deTunis, Tunis El Manar University, 2092 Tunis (Tunisia); Dimassi, W. [Laboratoire de Photovoltaïque, Centre de Recherches et des Technologies de l' Energie, Technopôle de Borj-Cédria, BP 95, Hammam-Lif 2050 (Tunisia); Amlouk, M. [Unité de Physique des Dispositifs a Semi-conducteurs, Faculté des Sciences deTunis, Tunis El Manar University, 2092 Tunis (Tunisia)

2015-07-15

Highlights: • A facile route to synthesize large-scale rod-like Sb{sub 2}S{sub 3} micro-wires was presented. • A deep analysis conjoint between band tails, band gap alteration and electrical model. • The band gap is 1.75 eV which may hold for solar energy conversion. - Abstract: Stibnite (Sb{sub 2}S{sub 3}) micro-wires have been grown on glass substrates by sulfuration of Sb thermal evaporated film in a vacuum sealed tube in presence of sulfur powder at 300 °C for 6 h. X-ray diffraction and Raman spectroscopy techniques indicate that the synthesized micro-wires have an orthorhombic structure. SEM micrographs show rod-shaped micro-wires with a typical length of several tens of micrometers and a diameter of the order of 0.5 μm. The absorption coefficient dependence on the photon energy in the UV–visible range revealed the existence of a direct transition with an energy band gap of about 1.7 eV. Moreover, the band tails and localized states which are related to the level of defects in the material will be presented. These parameters were determined from the exponential absorption profile. All these results have been evaluated and discussed in terms of alteration of band gap edge and electrical measurements.

Activation of toll-like receptors 2 and 4 by gram-negative periodontal bacteria

NARCIS (Netherlands)

Kikkert, R.; Laine, M. L.; Aarden, L. A.; van Winkelhoff, A. J.

2007-01-01

BACKGROUND/AIMS: Periodontitis is a chronic infectious disease associated with a gram-negative subgingival microflora. Bacterial components stimulate, among other receptors, Toll-like receptor (TLR) 2 and/or TLR4. Accumulating evidence indicates that both qualitatively and quantitatively distinct

Silver-doped manganese dioxide and trioxide nanoparticles inhibit both gram positive and gram negative pathogenic bacteria.

Science.gov (United States)

Kunkalekar, R K; Prabhu, M S; Naik, M M; Salker, A V

2014-01-01

Palladium, ruthenium and silver-doped MnO2 and silver doped Mn2O3 nanoparticles were synthesized by simple co-precipitation technique. SEM-TEM analysis revealed the nano-size of these synthesized samples. XPS data illustrates that Mn is present in 4+ and 3+ oxidation states in MnO2 and Mn2O3 respectively. Thermal analysis gave significant evidence for the phase changes with increasing temperature. Antibacterial activity of these synthesized nanoparticles on three Gram positive bacterial cultures (Staphylococcus aureus ATCC 6538, Streptococcus epidermis ATCC 12228, Bacillus subtilis ATCC 6633) and three Gram negative cultures (Escherichia coli ATCC 8739, Salmonella abony NCTC 6017 and Klebsiella pneumoniae ATCC 1003) was investigated using a disc diffusion method and live/dead assay. Only Ag-doped MnO2 and Ag-doped Mn2O3 nanoparticles showed antibacterial property against all six-test bacteria but Ag-doped MnO2 was found to be more effective than Ag-doped Mn2O3. Copyright © 2013 Elsevier B.V. All rights reserved.

A non-contact shape measuring system using an artificial neural network

International Nuclear Information System (INIS)

Jeon, Woo Tae; Lee, Myung Chan; Koh, Duck Joon; Cho, Hyung Suck

1996-01-01

We developed a non-contact shape measuring device using computer image processing technology. We present a method of calibrating a CCD video camera and a laser range finder which is the most important step toward making an accurate shape measuring system. An artificial neural network is used for the calibration. Our measurement system is composed of a semiconductor laser, a CCD video camera, a personal computer, and a linear motion table. We think that the developed system could be used for measuring the change in shape of the spent nuclear fuel rod before and after irradiation which is one of the most important tasks for developing a better nuclear fuel. A radiation shield is suggested for the possible utilization of the range finder in radioactive environment

Biodegradation of shea nut cake by indigenous soil bacteria

African Journals Online (AJOL)

User

chemical or physical treatment of the waste since the ... resistance to heat was conducted by heating a 24 h ... Effect of pH, Temperature and Yeast extract on .... Non-Lactose Fermenter; Gram= Gram Reaction; GNR= Gram Negative Rods; ...

Hydraulic fracture conductivity: effects of rod-shaped proppant from lattice-Boltzmann simulations and lab tests

Science.gov (United States)

Osiptsov, Andrei A.

2017-06-01

The goal of this study is to evaluate the conductivity of random close packings of non-spherical, rod-shaped proppant particles under the closure stress using numerical simulation and lab tests, with application to the conductivity of hydraulic fractures created in subterranean formation to stimulate production from oil and gas reservoirs. Numerical simulations of a steady viscous flow through proppant packs are carried out using the lattice Boltzmann method for the Darcy flow regime. The particle packings were generated numerically using the sequential deposition method. The simulations are conducted for packings of spheres, ellipsoids, cylinders, and mixtures of spheres with cylinders at various volumetric concentrations. It is demonstrated that cylinders provide the highest permeability among the proppants studied. The dependence of the nondimensional permeability (scaled by the equivalent particle radius squared) on porosity obtained numerically is well approximated by the power-law function: K /Rv2 = 0.204ϕ4.58 in a wide range of porosity: 0.3 ≤ ϕ ≤ 0.7. Lattice-Boltzmann simulations are cross-verified against finite-volume simulations using Navier-Stokes equations for inertial flow regime. Correlations for the normalized beta-factor as a function of porosity and normalized permeability are presented as well. These formulae are in a good agreement with the experimental measurements (including packings of rod-shaped particles) and existing laboratory data, available in the porosity range 0.3 ≤ ϕ ≤ 0.5. Comparison with correlations by other authors is also given.

Pharmacodynamic profiling of doripenem, imipenem and meropenem against prevalent Gram-negative organisms in the Asia-Pacific region.

Science.gov (United States)

Kiratisin, Pattarachai; Keel, Rebecca A; Nicolau, David P

2013-01-01

Carbapenems are increasingly being utilised owing to the escalating prevalence of antimicrobial-resistant Gram-negative bacteria from community and hospital settings. In this study, pharmacodynamic profiles of doripenem, imipenem and meropenem were evaluated against Gram-negative bacteria isolated from hospitalised patients. MICs for carbapenems were determined for Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa and Acinetobacter baumannii obtained from the COMPACT II programme conducted in the Asia-Pacific region. Monte Carlo simulations were undertaken to assess the pharmacodynamic profile of carbapenems against each of the pathogens. All carbapenem regimens achieved optimal exposures [cumulative fraction of response (CFR) ≥90%] against E. coli and K. pneumoniae. Against P. aeruginosa, doripenem achieved 81.3-95.3% CFR, imipenem achieved 55.2-77.9% CFR and meropenem achieved 71.9-91.3% CFR; only doripenem regimens of 4-h infusion of 1000 mg every 8h (q8h) and 1-h and 4-h infusion of 2000 mg q8h and a meropenem regimen of 3-h infusion of 2000 mg q8h obtained optimal exposures; all carbapenem regimens showed slight (1-7%) improvement in CFRs in favour of isolates collected from ICU sources. Against A. baumannii, CFRs were much lower (25.9-46.7% CFR) and no carbapenem regimens achieved optimal exposure in or outside the ICU. Owing to the high potency of carbapenems against these Enterobacteriaceae populations, standard regimens are likely to perform well in the Asia-Pacific region. However, larger doses combined with prolonged infusions will be required to increase the CFR for these carbapenems against resistant non-fermenting Gram-negatives such as P. aeruginosa and A. baumannii that are prevalent in these countries. Copyright © 2012 Elsevier B.V. and the International Society of Chemotherapy. All rights reserved.

Effect of Aqueous Garlic Extract (AGE) and gamma irradiation on some Bacterial Strains

International Nuclear Information System (INIS)

Awny, N.M; Tawfik, Z.S; Abu Nor, S.M; El-Saled, K.M.

2005-01-01

In the present study the sensitivity of four bacterial strains; Salmonella typhimurium, Escherichia coli, Bacillus subtilis and Bacillus pumilus were tested towards the antibacterial effect of aqueous garlic extract (AGE) with different concentration. The results indicated that, the Gram positive spore forming strains, Bacillus subtilis and Bacillus pumilus treated with AGE from 0 to 70μ1/m1 were more resistant than Gram negative non-spore forming ones, Salmonella typhimurium and Escherichia coli treated with AGE from 0 to 24 μ1/m1. The effect of AGE treatment on the radiosensitivity of the tested bacterial strains showed that, AGE treatment before γ-irradiation induced a higher protection than treatment immediately after γ-irradiation. The ultrastructure configuration of untreated strains, treated with AGE or irradiation and combination between AGE and Irradiation, were investigated using transmission electron microscope (TEM). The results indicated that, ultra-structures configuration of the cells treated with AGE before irradiation appeared with less damage than those of cells irradiated without AGE treatment

Quantification of Nonproteolytic Clostridium botulinum Spore Loads in Food Materials.

Science.gov (United States)

Barker, Gary C; Malakar, Pradeep K; Plowman, June; Peck, Michael W

2016-01-04

We have produced data and developed analysis to build representations for the concentration of spores of nonproteolytic Clostridium botulinum in materials that are used during the manufacture of minimally processed chilled foods in the United Kingdom. Food materials are categorized into homogenous groups which include meat, fish, shellfish, cereals, fresh plant material, dairy liquid, dairy nonliquid, mushroom and fungi, and dried herbs and spices. Models are constructed in a Bayesian framework and represent a combination of information from a literature survey of spore loads from positive-control experiments that establish a detection limit and from dedicated microbiological tests for real food materials. The detection of nonproteolytic C. botulinum employed an optimized protocol that combines selective enrichment culture with multiplex PCR, and the majority of tests on food materials were negative. Posterior beliefs about spore loads center on a concentration range of 1 to 10 spores kg(-1). Posterior beliefs for larger spore loads were most significant for dried herbs and spices and were most sensitive to the detailed results from control experiments. Probability distributions for spore loads are represented in a convenient form that can be used for numerical analysis and risk assessments. Copyright © 2016 Barker et al.

O-antigen protects gram-negative bacteria from histone killing.

Directory of Open Access Journals (Sweden)

Catherine Chaput

Full Text Available Beyond their traditional role of wrapping DNA, histones display antibacterial activity to Gram-negative and -positive bacteria. To identify bacterial components that allow survival to a histone challenge, we selected resistant bacteria from homologous Escherichia coli libraries that harbor plasmids carrying pieces of the chromosome in different sizes. We identified genes required for exopolysaccharide production and for the synthesis of the polysaccharide domain of the lipopolysaccharide, called O-antigen. Indeed, O-antigen and exopolysaccharide conferred further resistance to histones. Notably, O-antigen also conferred resistance to histones in the pathogens Shigella flexneri and Klebsiella pneumoniae.

Why Rods and Cocci

Indian Academy of Sciences (India)

Bacteria exhibit a wide variety of shapes but the commonly studied species of bacteria are generally either spherical in shape which are called cocci (singular coccus) or have a cylindrical shape and are called rods or bacilli (singular bacillus). In reality rods and cocci are the ends of a continuum. Sonle of the cocci are.

Acid and bile tolerance of spore-forming lactic acid bacteria.

Science.gov (United States)

Hyronimus, B; Le Marrec, C; Sassi, A H; Deschamps, A

2000-11-01

Criteria for screening probiotics such as bile tolerance and resistance to acids were studied with 13 spore-forming lactic acid producing bacteria. Different strains of Sporolactobacillus, Bacillus laevolacticus, Bacillus racemilacticus and Bacillus coagulans grown in MRS broth were subjected to low pH conditions (2, 2.5 and 3) and increasing bile concentrations. Among these microorganisms, Bacillus laevolacticus DSM 6475 and all Sporolactobacillus strains tested except Sporolactobacillus racemicus IAM 12395, were resistant to pH 3. Only Bacillus racemilacticus and Bacillus coagulans strains were tolerant to bile concentrations over 0.3% (w/v).

Apparatus and method for preventing the rotation of rods used in nuclear fuel assemblies

International Nuclear Information System (INIS)

Pilgrim, L.G. Jr.; Jackson, L.F.

1985-01-01

Apparatus and method for preventing the rotation of one or more elongated rods used in nuclear fuel assemblies include an end plug secured to one longitudinal end of such an elongated rod and having an out-of-cavity, non-round structure affixed thereto and configured to mate with a complementary shaped structure in a lower tie plate of a nuclear fuel assembly in such a manner as to prevent the rotation of the rod about its longitudinal axis. In one embodiment, the end plug includes a pair of flats formed on a portion of the end plug and configured to abut against a pair of flats formed on the outer surface of a cylindrical boss or sleeve of the lower tie plate, thereby to prevent the rotation of the rod. In another embodiment, four grooves, disposed 90 0 apart about the periphery of an end plug of a rod form a spline. The grooves are configured to receive four, radially inwardly protruding, key members disposed 90 0 apart about the periphery of a sleeve secured to the lower tie plate, thereby to prevent the rotation of the rod. In a further embodiment, a sleeve is secured to an end plug of a rod and includes four elongated slots disposed 90 0 apart about the periphery of the sleeve and configured in width, depth and spacing to receive and mate with four web portions of the lower tie plate of the nuclear fuel assembly, thereby to secure the rod against rotation about its longitudinal axis

Study of the antibacterial effects of chitosans on Bacillus cereus (and its spores) by atomic force microscopy imaging and nanoindentation

Energy Technology Data Exchange (ETDEWEB)

Fernandes, Joao C. [Escola Superior de Biotecnologia, Universidade Catolica Portuguesa, Rua Dr. Antonio Bernardino de Almeida, 4200-072 Porto (Portugal); Eaton, Peter, E-mail: peter.eaton@fc.up.pt [REQUIMTE, Departamento de Quimica, Faculdade de Ciencias da Universidade do Porto, Rua do Campo Alegre, 4169-007 Porto (Portugal); Gomes, Ana M.; Pintado, Manuela E.; Xavier Malcata, F. [Escola Superior de Biotecnologia, Universidade Catolica Portuguesa, Rua Dr. Antonio Bernardino de Almeida, 4200-072 Porto (Portugal)

2009-07-15

Bacillus cereus is a Gram-positive, spore-forming bacterium that is widely distributed in nature. Its intrinsic thermal resistance coupled with the extraordinary resistance against common food preservation techniques makes it one of the most frequent food-poisoning microorganisms causing both intoxications and infections. In order to control B. cereus growth/sporulation, and hence minimize the aforementioned hazards, several antimicrobial compounds have been tested. The aim of this work was to assess by atomic force microscopy (AFM) the relationship between the molecular weight (MW) of chitosan and its antimicrobial activity upon both vegetative and resistance forms of B. cereus. The use of AFM imaging studies helped us to understand how chitosans with different MW act differently upon B. cereus. Higher MW chitosans (628 and 100 kDa) surrounded both forms of B. cereus cells by forming a polymer layer-which eventually led to the death of the vegetative form by preventing the uptake of nutrients yet did not affect the spores since these can survive for extended periods without nutrients. Chitooligosaccharides (COS) (<3 kDa), on the other hand, provoked more visible damages in the B. cereus vegetative form-most probably due to the penetration of the cells by the COS. The use of COS by itself on B. cereus spores was not enough for the destruction of a large number of cells, but it may well weaken the spore structure and its ability to contaminate, by inducing exosporium loss.

Study of the antibacterial effects of chitosans on Bacillus cereus (and its spores) by atomic force microscopy imaging and nanoindentation

International Nuclear Information System (INIS)

Fernandes, Joao C.; Eaton, Peter; Gomes, Ana M.; Pintado, Manuela E.; Xavier Malcata, F.

2009-01-01

Bacillus cereus is a Gram-positive, spore-forming bacterium that is widely distributed in nature. Its intrinsic thermal resistance coupled with the extraordinary resistance against common food preservation techniques makes it one of the most frequent food-poisoning microorganisms causing both intoxications and infections. In order to control B. cereus growth/sporulation, and hence minimize the aforementioned hazards, several antimicrobial compounds have been tested. The aim of this work was to assess by atomic force microscopy (AFM) the relationship between the molecular weight (MW) of chitosan and its antimicrobial activity upon both vegetative and resistance forms of B. cereus. The use of AFM imaging studies helped us to understand how chitosans with different MW act differently upon B. cereus. Higher MW chitosans (628 and 100 kDa) surrounded both forms of B. cereus cells by forming a polymer layer-which eventually led to the death of the vegetative form by preventing the uptake of nutrients yet did not affect the spores since these can survive for extended periods without nutrients. Chitooligosaccharides (COS) (<3 kDa), on the other hand, provoked more visible damages in the B. cereus vegetative form-most probably due to the penetration of the cells by the COS. The use of COS by itself on B. cereus spores was not enough for the destruction of a large number of cells, but it may well weaken the spore structure and its ability to contaminate, by inducing exosporium loss.

Cefepime restriction improves gram-negative overall resistance patterns in neonatal intensive care unit

Directory of Open Access Journals (Sweden)

Orlei Ribeiro de Araujo

Full Text Available Antibiotic restriction can be useful in maintaining bacterial susceptibility. The objective of this study was verify if restriction of cefepime, the most frequently used cephalosporin in our neonatal intensive care unit (NICU, would ameliorate broad-spectrum susceptibility of Gram-negative isolates. Nine hundred and ninety-five premature and term newborns were divided into 3 cohorts, according to the prevalence of cefepime use in the unit: Group 1 (n=396 comprised patients admitted from January 2002 to December 2003, period in which cefepime was the most used broad-spectrum antibiotic. Patients in Group 2 (n=349 were admitted when piperacillin/tazobactam replaced cefepime (January to December 2004 and in Group 3 (n=250 when cefepime was reintroduced (January to September 2005. Meropenem was the alternative third-line antibiotic for all groups. Multiresistance was defined as resistance to 2 or more unrelated antibiotics, including necessarily a third or fourth generation cephalosporin, piperacillin/tazobactam or meropenem. Statistics involved Kruskal-Wallis, Mann-Whitney and logrank tests, Kaplan-Meier analysis. Groups were comparable in length of stay, time of mechanical ventilation, gestational age and birth weight. Ninety-eight Gram-negative isolates were analyzed. Patients were more likely to remain free of multiresistant isolates by Kaplan-Meier analysis in Group 2 when compared to Group 1 (p=0.017 and Group 3 (p=0.003. There was also a significant difference in meropenem resistance rates. Cefepime has a greater propensity to select multiresistant Gram-negative pathogens than piperacillin/tazobactam and should not be used extensively in neonatal intensive care.

A Trojan-Horse Strategy Including a Bacterial Suicide Action for the Efficient Use of a Specific Gram-Positive Antibiotic on Gram-Negative Bacteria.

Science.gov (United States)

Schalk, Isabelle J

2018-05-10

In the alarming context of rising bacterial antibiotic resistance, there is an urgent need to discover new antibiotics or increase and/or enlarge the activity of those currently in use. The need for new antibiotics is even more urgent in the case of Gram-negative bacteria, such as Acinetobacter, Pseudomonas, and Enterobacteria, which have become resistant to many antibiotics and have an outer membrane with very low permeability to drugs. Vectorization of antibiotics using siderophores may be a solution to bypass such a bacterial wall: the drugs use the iron transporters of the outer membrane as gates to enter bacteria in a Trojan-horse strategy. Designing siderophore-antibiotics that can cross outer membranes has become almost routine, but their transport across the inner membrane is still a limiting step, as well as a strategy that allows dissociation of the antibiotic from the siderophore once inside the bacteria. Liu et al. ( J. Med. Chem. 2018 , DOI: 10.1021/acs.jmedchem.8b00218 ) report the synthesis of a siderophore-cephalosporin compound and demonstrate that β-lactams, such as cephalosporins, can serve as β-lactamase-triggered releasable linkers to allow intracellular delivery of Gram-positive antibiotics to Gram-negative bacteria.

The gram-negative bacterial periplasm: Size matters.

Directory of Open Access Journals (Sweden)

Samuel I Miller

2018-01-01

Full Text Available Gram-negative bacteria are surrounded by two membrane bilayers separated by a space termed the periplasm. The periplasm is a multipurpose compartment separate from the cytoplasm whose distinct reducing environment allows more efficient and diverse mechanisms of protein oxidation, folding, and quality control. The periplasm also contains structural elements and important environmental sensing modules, and it allows complex nanomachines to span the cell envelope. Recent work indicates that the size or intermembrane distance of the periplasm is controlled by periplasmic lipoproteins that anchor the outer membrane to the periplasmic peptidoglycan polymer. This periplasm intermembrane distance is critical for sensing outer membrane damage and dictates length of the flagellar periplasmic rotor, which controls motility. These exciting results resolve longstanding debates about whether the periplasmic distance has a biological function and raise the possibility that the mechanisms for maintenance of periplasmic size could be exploited for antibiotic development.

Control rod drives

International Nuclear Information System (INIS)

Yamanaka, Toshikatsu.

1979-01-01

Purpose: To protect bellows against failures due to negative pressure to prevent the loss of pressure balance caused by the expansion of the bellows upon scram. Constitution: An expansion pipe connected to the control rod drive is driven along a guide pipe to insert a control rod into the reactor core. Expansible bellows are provided at the step between the expansion pipe and the guide pipe. Further, a plurality of bore holes or slits are formed on the side wall of the guide pipe corresponding to the expansion portion of the bellows. In such an arrangement, when the expansion pipe falls rapidly and the bellows are expanded upon scram, the volume between each of the pipes of the bellows and the guide pipe is increased to produce a negative pressure, but the effect of the negative pressure on the bellows can be eliminated by the flowing-in of coolants corresponding to that pressure through the bore holes or the slits. (Furukawa, Y.)

Sporulation environment influences spore properties in Bacillus: evidence and insights on underlying molecular and physiological mechanisms.

Science.gov (United States)

Bressuire-Isoard, Christelle; Broussolle, Véronique; Carlin, Frédéric

2018-05-17

Bacterial spores are resistant to physical and chemical insults, which make them a major concern for public health and for industry. Spores help bacteria to survive extreme environmental conditions that vegetative cells cannot tolerate. Spore resistance and dormancy are important properties for applications in medicine, veterinary health, food safety, crop protection, and other domains. The resistance of bacterial spores results from a protective multilayered structure and from the unique composition of the spore core. The mechanisms of sporulation and germination, the first stage after breaking of dormancy, and organization of spore structure have been extensively studied in Bacillus species. This review aims to illustrate how far the structure, composition and properties of spores are shaped by the environmental conditions in which spores form. We look at the physiological and molecular mechanisms underpinning how sporulation media and environment deeply affect spore yield, spore properties like resistance to wet heat and physical and chemical agents, germination, and further growth. For example, spore core water content decreases as sporulation temperature increases, and resistance to wet heat increases. Controlling the fate of Bacillus spores is pivotal to controlling bacterial risks and process efficiencies in, for example, the food industry, and better control hinges on better understanding how sporulation conditions influence spore properties.

Methods for Confirming the Gram Reaction of Gram-variable Bacillus Species Isolated from Tobacco

Directory of Open Access Journals (Sweden)

Morin A

2014-12-01

Full Text Available Bacillus is a predominant genus of bacteria isolated from tobacco. The Gram stain is the most commonly used and most important of all diagnostic staining techniques in microbiology. In order to help confirm the Gram positivity of Bacillus isolates from tobacco, three methods using the chemical differences of the cell wall and membrane of Gram-positive and Gram-negative bacteria were investigated: the KOH (potassium hydroxide, the LANA (L-alanine-4-nitroanilide, and the vancomycin susceptibility tests. When colonies of Gram-negative bacteria are treated with 3% KOH solution, a slimy suspension is produced, probably due to destruction of the cell wall and liberation of deoxyribonucleic acid (DNA. Gram-positive cell walls resist KOH treatment. The LANA test reveals the presence of a cell wall aminopeptidase that hydrolyzes the L-alanine-4-nitroanilide in Gram-negative bacteria. This enzyme is absent in Gram-positive bacteria. Vancomycin is a glycopeptide antibiotic inhibiting the cell wall peptido-glycan synthesis of Gram-positive microorganisms. Absence of lysis with KOH, absence of hydrolysis of LANA, and susceptibility to vancomycin were used with the Gram reaction to confirm the Gram positivity of various Bacillus species isolated from tobacco. B. laevolacticus excepted, all Bacillus species tested showed negative reactions to KOH and LANA tests, and all species were susceptible to vancomycin (5 and 30 µg.

In vitro activity of tigecycline and comparator agents against a global collection of Gram-negative and Gram-positive organisms: tigecycline Evaluation and Surveillance Trial 2004 to 2007.

Science.gov (United States)

Garrison, Mark W; Mutters, Reinier; Dowzicky, Michael J

2009-11-01

The Tigecycline Evaluation and Surveillance Trial began in 2004 to monitor the in vitro activity of tigecycline and comparator agents against a global collection of Gram-negative and Gram-positive pathogens. Against Gram negatives (n = 63 699), tigecycline MIC(90)'s ranged from 0.25 to 2 mg/L for Escherichia coli, Haemophilus influenzae, Acinetobacter baumannii, Klebsiella oxytoca, Enterobacter cloacae, Klebsiella pneumoniae, and Serratia marcescens (but was > or =32 for Pseudomonas aeruginosa). Against Gram-positive organisms (n = 32 218), tigecycline MIC(90)'s were between 0.06 and 0.25 mg/L for Streptococcus pneumoniae, Enterococcus faecium, Streptococcus agalactiae, Staphylococcus aureus, and Enterococcus faecalis. The in vitro activity of tigecycline was maintained against resistant phenotypes, including multidrug-resistant A. baumannii (9.2% of isolates), extended-spectrum beta-lactamase-producing E. coli (7.0%) and K. pneumoniae (14.0%), beta-lactamase-producing H. influenzae (22.2%), methicillin-resistant S. aureus (44.5%), vancomycin-resistant E. faecium (45.9%) and E. faecalis (2.8%), and penicillin-resistant S. pneumoniae (13.8%). Tigecycline represents a welcome addition to the armamentarium against difficult to treat organisms.

With respect to coefficient of linear thermal expansion, bacterial vegetative cells and spores resemble plastics and metals, respectively.

Science.gov (United States)

Nakanishi, Koichi; Kogure, Akinori; Fujii, Takenao; Kokawa, Ryohei; Deuchi, Keiji; Kuwana, Ritsuko; Takamatsu, Hiromu

2013-10-09

If a fixed stress is applied to the three-dimensional z-axis of a solid material, followed by heating, the amount of thermal expansion increases according to a fixed coefficient of thermal expansion. When expansion is plotted against temperature, the transition temperature at which the physical properties of the material change is at the apex of the curve. The composition of a microbial cell depends on the species and condition of the cell; consequently, the rate of thermal expansion and the transition temperature also depend on the species and condition of the cell. We have developed a method for measuring the coefficient of thermal expansion and the transition temperature of cells using a nano thermal analysis system in order to study the physical nature of the cells. The tendency was seen that among vegetative cells, the Gram-negative Escherichia coli and Pseudomonas aeruginosa have higher coefficients of linear expansion and lower transition temperatures than the Gram-positive Staphylococcus aureus and Bacillus subtilis. On the other hand, spores, which have low water content, overall showed lower coefficients of linear expansion and higher transition temperatures than vegetative cells. Comparing these trends to non-microbial materials, vegetative cells showed phenomenon similar to plastics and spores showed behaviour similar to metals with regards to the coefficient of liner thermal expansion. We show that vegetative cells occur phenomenon of similar to plastics and spores to metals with regard to the coefficient of liner thermal expansion. Cells may be characterized by the coefficient of linear expansion as a physical index; the coefficient of linear expansion may also characterize cells structurally since it relates to volumetric changes, surface area changes, the degree of expansion of water contained within the cell, and the intensity of the internal stress on the cellular membrane. The coefficient of linear expansion holds promise as a new index for

Technique for preparation of anaerobic microbes: Rodshaped cellulolytic bacteria

Directory of Open Access Journals (Sweden)

Amlius Thalib

2001-10-01

Full Text Available Preparation of anaerobic-rod cellulolytic bacteria with coating technique has been conducted. Steps of the processes involved were cultivation, coating, evaporation, and drying. Coating agent used was Gum Arabic, and drying techniquesconducted were freeze drying and sun drying. pH of culture media was firstly optimized to obtain the maximal population ofbacteria. Both coated and uncoated preparates were subjected to drying. Morphological and Gram type identifications showed that uncoated preparate dried with freeze drying is not contaminated (ie. all bacteria are rod shape with Gram-negative type while the one dried with sun drying is not morphologically pure (ie. containing of both rod and coccus shapes with Gram negative and positive. The coated preparates dried by both freeze and sun drying, were not contaminated (ie. all are rods with Gram-negative. The coating and drying processes decreased viability of preparates significantly. However, the decreasing of viability of coated preparate are lower than uncoated preparate (ie. 89 vs. 97%. Total count of bacteria in sun-drying coated preparate are higher (P<0.05 than the uncoated preparate (ie. 3.38 x 1010 vs. 1.97 x 1010 colony/g DM. Activity of sun-drying coated preparate to digest elephant grass and rice straw was higher (P<0.01 than the sun-drying uncoated preparate with the in vitro DMD values were 42.7 vs. 35.5% for elephant grass substrate and 29.3 vs. 24.6% for rice straw substrate. Therefore, it is concluded that coating technique has a positive effects on the preparation of rumen bacteria.

The Conserved Spore Coat Protein SpoVM Is Largely Dispensable in Clostridium difficile Spore Formation.

Science.gov (United States)

Ribis, John W; Ravichandran, Priyanka; Putnam, Emily E; Pishdadian, Keyan; Shen, Aimee

2017-01-01

The spore-forming bacterial pathogen Clostridium difficile is a leading cause of health care-associated infections in the United States. In order for this obligate anaerobe to transmit infection, it must form metabolically dormant spores prior to exiting the host. A key step during this process is the assembly of a protective, multilayered proteinaceous coat around the spore. Coat assembly depends on coat morphogenetic proteins recruiting distinct subsets of coat proteins to the developing spore. While 10 coat morphogenetic proteins have been identified in Bacillus subtilis , only two of these morphogenetic proteins have homologs in the Clostridia : SpoIVA and SpoVM. C. difficile SpoIVA is critical for proper coat assembly and functional spore formation, but the requirement for SpoVM during this process was unknown. Here, we show that SpoVM is largely dispensable for C. difficile spore formation, in contrast with B. subtilis . Loss of C. difficile SpoVM resulted in modest decreases (~3-fold) in heat- and chloroform-resistant spore formation, while morphological defects such as coat detachment from the forespore and abnormal cortex thickness were observed in ~30% of spoVM mutant cells. Biochemical analyses revealed that C. difficile SpoIVA and SpoVM directly interact, similarly to their B. subtilis counterparts. However, in contrast with B. subtilis , C. difficile SpoVM was not essential for SpoIVA to encase the forespore. Since C. difficile coat morphogenesis requires SpoIVA-interacting protein L (SipL), which is conserved exclusively in the Clostridia , but not the more broadly conserved SpoVM, our results reveal another key difference between C. difficile and B. subtilis spore assembly pathways. IMPORTANCE The spore-forming obligate anaerobe Clostridium difficile is the leading cause of antibiotic-associated diarrheal disease in the United States. When C. difficile spores are ingested by susceptible individuals, they germinate within the gut and

Spatio-Temporal Patterns in Colonies of Rod-Shaped Bacteria

Science.gov (United States)

Kitsunezaki, S.

In incubation experiments of bacterial colonies of Proteus Mirabilis, macroscopic spatio-temporal patterns, such as turbulent and unidirectional spiral patterns, appear in colonies. Considering only kinetic propeties of rod-shaped bacteria, we propose a phenomenological model for the directional and positional distributions. As the average density increases, homogeneous states bifurcate sub-critically into nonuniform states exhibiting localized collective motion, and spiral patterns appear for sufficiently large density. These patterns result from interactions between the local bacteria densities and the order parameter representing collective motion. Our model can be described by reduced equations using a perturbative method for large density. The unidirectionality of sprial rotation is also discussed.

An unusual class of anthracyclines potentiate Gram-positive antibiotics in intrinsically resistant Gram-negative bacteria.

Science.gov (United States)

Cox, Georgina; Koteva, Kalinka; Wright, Gerard D

2014-07-01

An orthogonal approach taken towards novel antibacterial drug discovery involves the identification of small molecules that potentiate or enhance the activity of existing antibacterial agents. This study aimed to identify natural-product rifampicin adjuvants in the intrinsically resistant organism Escherichia coli. E. coli BW25113 was screened against 1120 actinomycete fermentation extracts in the presence of subinhibitory (2 mg/L) concentrations of rifampicin. The active molecule exhibiting the greatest rifampicin potentiation was isolated using activity-guided methods and identified using mass and NMR spectroscopy. Susceptibility testing and biochemical assays were used to determine the mechanism of antibiotic potentiation. The anthracycline Antibiotic 301A(1) was isolated from the fermentation broth of a strain of Streptomyces (WAC450); the molecule was shown to be highly synergistic with rifampicin (fractional inhibitory concentration index = 0.156) and moderately synergistic with linezolid (FIC index = 0.25) in both E. coli and Acinetobacter baumannii. Activity was associated with inhibition of efflux and the synergistic phenotype was lost when tested against E. coli harbouring mutations within the rpoB gene. Structure-activity relationship studies revealed that other anthracyclines do not synergize with rifampicin and removal of the sugar moiety of Antibiotic 301A(1) abolishes activity. Screening only a subsection of our natural product library identified a small-molecule antibiotic adjuvant capable of sensitizing Gram-negative bacteria to antibiotics to which they are ordinarily intrinsically resistant. This result demonstrates the great potential of this approach in expanding antibiotic effectiveness in the face of the growing challenge of resistance in Gram-negatives. © The Author 2014. Published by Oxford University Press on behalf of the British Society for Antimicrobial Chemotherapy. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.

Protective guide structure for reactor control rod

International Nuclear Information System (INIS)

Ban, Minoru; Umeda, Kenji; Kubo, Noboru; Ito, Tomohiro.

1996-01-01

The present invention provides an improved protective guide structure for control rods, which does not cause swirling of coolants and resonance even though a slit is formed on a protective tube which surrounds a control rod element in a PWR type reactor. Namely, a reactor control rod is constituted with elongated control elements collectively bundled in the form of a cluster. The protective guide structure protectively guides the collected constituent at the upper portion of a reactor container. The protective structure comprises a plurality of protective tubes each having a C-shaped cross section disposed in parallel for receiving control rod elements individually in which the corners of the opening of the cross section of the protective tube are chamfered to an appropriate configuration. With such a constitution, even if coolant flows in a circumferential direction along the protective tubes surrounding the control rod elements, no shearing stream is caused to the coolants flow since the corners of the cross sectional opening (slit) of the tube are chamfered. Accordingly, occurrence of swirlings can be suppressed. (I.S.)

Inhibition of various gram-positive and gram-negative bacteria growth on selenium nanoparticle coated paper towels.

Science.gov (United States)

Wang, Qi; Larese-Casanova, Philip; Webster, Thomas J

2015-01-01

There are wide spread bacterial contamination issues on various paper products, such as paper towels hanging in sink splash zones or those used to clean surfaces, filter papers used in water and air purifying systems, and wrappings used in the food industry; such contamination may lead to the potential spread of bacteria and consequent severe health concerns. In this study, selenium nanoparticles were coated on normal paper towel surfaces through a quick precipitation method, introducing antibacterial properties to the paper towels in a healthy way. Their effectiveness at preventing biofilm formation was tested in bacterial assays involving Staphylococcus aureus, Pseudomonas aeruginosa, Escherichia coli, and Staphylococcus epidermidis. The results showed significant and continuous bacteria inhibition with about a 90% reduction from 24 to 72 hours for gram-positive bacteria including S. aureus and S. epidermidis. The selenium coated paper towels also showed significant inhibition of gram-negative bacteria like P. aeruginosa and E. coli growth at about 57% and 84%, respectively, after 72 hours of treatment. Therefore, this study established a promising selenium-based antibacterial strategy to prevent bacterial growth on paper products, which may lead to the avoidance of bacteria spreading and consequent severe health concerns.

A case of newborn with community acquired pneumonia caused by Cupriavidus pauculus.

Science.gov (United States)

Aydın, Banu; Dilli, Dilek; Zenciroğlu, Ayşegül; Okumuş, Nurullah; Ozkan, Sengül; Tanır, Gönül

2012-01-01

Cupriavidus pauculus is a gram-negative, aerobic, non-spore forming, non-fermentative motile bacillus. The bacillus can be isolated from water, bottled mineral water, and water from ultrafiltration systems in hospital setting. C. pauculus rarely causes human infections, however it may be an infectious agent especially in immunocompromised individuals. In this report, we present the first case of community acquired pneumonia caused by C. pauculus in a previously healthy newborn who was hospitalized in neonatal intensive care unit on postnatal day 16 because of respiratory distress.

Method of forming magnetostrictive rods from rare earth-iron alloys

Science.gov (United States)

McMasters, O. Dale

1986-09-02

Rods of magnetrostructive alloys of iron with rare earth elements are formed by flowing a body of rare earth-iron alloy in a crucible enclosed in a chamber maintained under an inert gas atmosphere, forcing such molten rare-earth-iron alloy into a hollow mold tube of refractory material positioned with its lower end portion within the molten body by means of a pressure differential between the chamber and mold tube and maintaining a portion of the molten alloy in the crucible extending to a level above the lower end of the mold tube so that solid particles of higher melting impurities present in the alloy collect at the surface of the molten body and remain within the crucible as the rod is formed in the mold tube.

Bacillus cereus and related species.

OpenAIRE

Drobniewski, F A

1993-01-01

Bacillus cereus is a gram-positive aerobic or facultatively anaerobic spore-forming rod. It is a cause of food poisoning, which is frequently associated with the consumption of rice-based dishes. The organism produces an emetic or diarrheal syndrome induced by an emetic toxin and enterotoxin, respectively. Other toxins are produced during growth, including phospholipases, proteases, and hemolysins, one of which, cereolysin, is a thiol-activated hemolysin. These toxins may contribute to the pa...

Overexpression of the endothelial protein C receptor is detrimental during pneumonia-derived gram-negative sepsis (Melioidosis.

Directory of Open Access Journals (Sweden)

Liesbeth M Kager

Full Text Available The endothelial protein C receptor (EPCR enhances anticoagulation by accelerating activation of protein C to activated protein C (APC and mediates anti-inflammatory effects by facilitating APC-mediated signaling via protease activated receptor-1. We studied the role of EPCR in the host response during pneumonia-derived sepsis instigated by Burkholderia (B. pseudomallei, the causative agent of melioidosis, a common form of community-acquired Gram-negative (pneumosepsis in South-East Asia.Soluble EPCR was measured in plasma of patients with septic culture-proven melioidosis and healthy controls. Experimental melioidosis was induced by intranasal inoculation of B. pseudomallei in wild-type (WT mice and mice with either EPCR-overexpression (Tie2-EPCR or EPCR-deficiency (EPCR(-/-. Mice were sacrificed after 24, 48 or 72 hours. Organs and plasma were harvested to measure colony forming units, cellular influxes, cytokine levels and coagulation parameters. Plasma EPCR-levels were higher in melioidosis patients than in healthy controls and associated with an increased mortality. Tie2-EPCR mice demonstrated enhanced bacterial growth and dissemination to distant organs during experimental melioidosis, accompanied by increased lung damage, neutrophil influx and cytokine production, and attenuated coagulation activation. EPCR(-/- mice had an unremarkable response to B. pseudomallei infection as compared to WT mice, except for a difference in coagulation activation in plasma.Increased EPCR-levels correlate with accelerated mortality in patients with melioidosis. In mice, transgenic overexpression of EPCR aggravates outcome during Gram-negative pneumonia-derived sepsis caused by B. pseudomallei, while endogenous EPCR does not impact on the host response. These results add to a better understanding of the regulation of coagulation during severe (pneumosepsis.

Botulism outbreaks in natural environments — an update

Directory of Open Access Journals (Sweden)

Mari eEspelund

2014-06-01

Full Text Available Clostridium botulinum comprises a diverse group of botulinum toxin-producing anaerobic rod-shaped spore-forming bacteria that are ubiquitously distributed in soils and aquatic sediments. Decomposition of plants, algae and animals creates anaerobic environments that facilitate growth of C. botulinum, which may then enter into food webs leading to intoxication of animals. Via saprophytic utilization of nutrients, the bacteria rapidly sporulate, creating a reservoir of highly robust spores. In the present review, we focus on the occurrence of C. botulinum in non-clinical environments, and examine factors influencing growth and environmental factors associated with botulism outbreaks. We also outline cases involving specific environments and their biota. In wetlands, it has been found that some C. botulinum strains can associate with toxin-unaffected organisms—including algae, plants, and invertebrates—in which the bacteria appear to germinate and stay in the vegetative form for longer periods of time. We suggest the need for future investigations to resolve issues related to the environments in which C. botulinum spores may accumulate and germinate, and where the vegetative forms may multiply.

Human anthrax as a re-emerging disease.

Science.gov (United States)

Doganay, Mehmet; Demiraslan, Hayati

2015-01-01

Anthrax is primarily a disease of herbivores and the etiological agent is B. anthracis which is a gram-positive, aerobic, spore-forming, and rod shaped bacterium. Bacillus anthracis spores are highly resistant to heat, pressure, ultraviolet and ionizing radiation, chemical agents and disinfectants. For these reasons, B. anthracis spores are an attractive choice as biological agents for the use of bioweapon and/or bioterrorism. Soil is the main reservoir for the infectious agent. The disease most commonly affects wild and domestic mammals. Human are secondarily infected by contact with infected animals and contaminated animal products or directly expose to B. anthracis spores. Anthrax occurs worldwide. This infection is still endemic or hyperendemic in both animals and humans in some part of areas of the world; particularly in Middle East, West Africa, Central Asia, some part of India, South America. However, some countries are claiming free of anthrax, and anthrax has become a re-emerging disease in western countries with the intentional outbreak. Currently, anthrax is classified according to its setting as (1) naturally occurring anthrax, (2) bioterrorism-related anthrax. Vast majority of human anthrax are occurring as naturally occurring anthrax in the world. It is also a threaten disease for western countries. The aim of this paper is to review the relevant patents, short historical perspective, microbiological and epidemiological features, clinical presentations and treatment.

Gram-Negative Bacterial Sensors for Eukaryotic Signal Molecules

Directory of Open Access Journals (Sweden)

Olivier Lesouhaitier

2009-09-01

Full Text Available Ample evidence exists showing that eukaryotic signal molecules synthesized and released by the host can activate the virulence of opportunistic pathogens. The sensitivity of prokaryotes to host signal molecules requires the presence of bacterial sensors. These prokaryotic sensors, or receptors, have a double function: stereospecific recognition in a complex environment and transduction of the message in order to initiate bacterial physiological modifications. As messengers are generally unable to freely cross the bacterial membrane, they require either the presence of sensors anchored in the membrane or transporters allowing direct recognition inside the bacterial cytoplasm. Since the discovery of quorum sensing, it was established that the production of virulence factors by bacteria is tightly growth-phase regulated. It is now obvious that expression of bacterial virulence is also controlled by detection of the eukaryotic messengers released in the micro-environment as endocrine or neuro-endocrine modulators. In the presence of host physiological stress many eukaryotic factors are released and detected by Gram-negative bacteria which in return rapidly adapt their physiology. For instance, Pseudomonas aeruginosa can bind elements of the host immune system such as interferon-γ and dynorphin and then through quorum sensing circuitry enhance its virulence. Escherichia coli sensitivity to the neurohormones of the catecholamines family appears relayed by a recently identified bacterial adrenergic receptor. In the present review, we will describe the mechanisms by which various eukaryotic signal molecules produced by host may activate Gram-negative bacteria virulence. Particular attention will be paid to Pseudomonas, a genus whose representative species, P. aeruginosa, is a common opportunistic pathogen. The discussion will be particularly focused on the pivotal role played by these new types of pathogen sensors from the sensing to the transduction

Evaluation of Inhibitory and Lethal Effects of Aqueous, Ethanolic and Hydroalcoholic Extracts of Aerial Parts of Salvia chorassanica against Some Gram-negative and Gram-positive Bacteria in Vitro

Directory of Open Access Journals (Sweden)

Azam Mehraban

2016-05-01

Full Text Available Abstract Background and Objectives: Development of bacterial resistance to antibiotics has led to an increased tendency to development of new more effective and non-toxic antimicrobial compounds. In this study, the inhibitory and lethal effects of aqueous, ethanolic, and hydroalcoholic extracts of aerial parts of Salvia chorassanica were evaluated against Listeria monocytogenes, Bacillus cereus, Salmonella typhi, and Escherichia coli O:157. Methods: In this study, Kirby–Bauer disk diffusion method was used to evaluate antimicrobial activity. In this method, bacteria were cultivated as grass culture in Mueller Hinton Agar (MHA media. To determine the minimum inhibitory concentration and minimum bactericidal concentration, micro-dilution method with ELISA and addition of phenyl tetrazolium chloride reagent, were used. Data were analyzed using one-way ANOVA and Duncan’s test at the significance level of p<0.05. Results: The highest diameter of inhibition in agar diffusion method was related to hydroalcoholic extract of aerial parts of Salvia chorassanica against Gram-positive bacteria Bacillus cereus. The amount of calculated MIC of hydro-alcoholic extract for Gram-positive bacteria was 30mg/ml. This amount was the lowest among other measured MIC. Conclusion: Based on the results of this study, Gram-negative bacteria showed more resistance to different extracts of aerial parts of Salvia chorassanica as compared to Gram-positive bacteria, so that Salmonella typhi was found to be the most resistant bacterium among the tested bacteria.

Spontaneous formation of non-uniform double helices for elastic rods under torsion

International Nuclear Information System (INIS)

Li, Hongyuan; Zhao, Shumin; Xia, Minggang; He, Siyu; Yang, Qifan; Yan, Yuming; Zhao, Hanqiao

2017-01-01

The spontaneous formation of double helices for filaments under torsion is common and significant. For example, the research on the supercoiling of DNA is helpful for understanding the replication and transcription of DNA. Similar double helices can appear in carbon nanotube yarns, cables, telephone wires and so forth. We noticed that non-uniform double helices can be produced due to the surface friction induced by the self-contact. Therefore an ideal model was presented to investigate the formation of double helices for elastic rods under torque. A general equilibrium condition which is valid for both the smooth surface and the rough surface situations is derived by using the variational method. By adding further constraints, the smooth and rough surface situations are investigated in detail respectively. Additionally, the model showed that the specific process of how to twist and slack the rod can determine the surface friction and hence influence the configuration of the double helix formed by rods with rough surfaces. Based on this principle, a method of manufacturing double helices with designed configurations was proposed and demonstrated. Finally, experiments were performed to verify the model and the results agreed well with the theory. - Highlights: • An ideal model is conceived to investigate the spontaneous formation of double helices for rods under torsion. • Variational method is used to obtain a universal result for the double helix formation process • Self-contact and surface friction is considered to analyze the non-uniform double helix. • A novel method of producing double helix with arbitrary configuration is proposed and demonstrated. • The experiment results agree well with the theory.

Spontaneous formation of non-uniform double helices for elastic rods under torsion

Energy Technology Data Exchange (ETDEWEB)

Li, Hongyuan [Department of Applied Physics, School of Science, Xi' an Jiaotong University, Shaanxi 710049 (China); Zhao, Shumin, E-mail: zhaosm@mail.xjtu.edu.cn [Department of Applied Physics, School of Science, Xi' an Jiaotong University, Shaanxi 710049 (China); Xia, Minggang [Department of Optical Information Science and Technology, School of Science, Xi' an Jiaotong University, 710049 (China); Laboratory of Nanostructure and Physics Properties, School of Science, Xi' an Jiaotong University, 710049 (China); He, Siyu [Department of Applied Physics, School of Science, Xi' an Jiaotong University, Shaanxi 710049 (China); Yang, Qifan [Department of Biomedical Engineering, School of Life Science and Technology, Xi' an Jiaotong University, Shaanxi 710049 (China); Yan, Yuming [Department of Electrical Engineering and Automation, School of Electrical Engineering, Xi' an Jiaotong University, Shaanxi 710049 (China); Zhao, Hanqiao [Department of Biomedical Engineering, School of Life Science and Technology, Xi' an Jiaotong University, Shaanxi 710049 (China)

2017-02-19

The spontaneous formation of double helices for filaments under torsion is common and significant. For example, the research on the supercoiling of DNA is helpful for understanding the replication and transcription of DNA. Similar double helices can appear in carbon nanotube yarns, cables, telephone wires and so forth. We noticed that non-uniform double helices can be produced due to the surface friction induced by the self-contact. Therefore an ideal model was presented to investigate the formation of double helices for elastic rods under torque. A general equilibrium condition which is valid for both the smooth surface and the rough surface situations is derived by using the variational method. By adding further constraints, the smooth and rough surface situations are investigated in detail respectively. Additionally, the model showed that the specific process of how to twist and slack the rod can determine the surface friction and hence influence the configuration of the double helix formed by rods with rough surfaces. Based on this principle, a method of manufacturing double helices with designed configurations was proposed and demonstrated. Finally, experiments were performed to verify the model and the results agreed well with the theory. - Highlights: • An ideal model is conceived to investigate the spontaneous formation of double helices for rods under torsion. • Variational method is used to obtain a universal result for the double helix formation process • Self-contact and surface friction is considered to analyze the non-uniform double helix. • A novel method of producing double helix with arbitrary configuration is proposed and demonstrated. • The experiment results agree well with the theory.

Epidemiology and molecular characterization of multidrug-resistant Gram-negative bacteria in Southeast Asia

Directory of Open Access Journals (Sweden)

Nuntra Suwantarat

2016-05-01

Full Text Available Abstract Background Multidrug-resistant Gram-negative bacteria (MDRGN, including extended-spectrum β-lactamases (ESBLs and multidrug-resistant glucose-nonfermenting Gram-negative bacilli (nonfermenters, have emerged and spread throughout Southeast Asia. Methods We reviewed and summarized current critical knowledge on the epidemiology and molecular characterization of MDRGN in Southeast Asia by PubMed searches for publications prior to 10 March 2016 with the term related to “MDRGN definition” combined with specific Southeast Asian country names (Thailand, Singapore, Malaysia, Vietnam, Indonesia, Philippines, Laos, Cambodia, Myanmar, Brunei. Results There were a total of 175 publications from the following countries: Thailand (77, Singapore (35, Malaysia (32, Vietnam (23, Indonesia (6, Philippines (1, Laos (1, and Brunei (1. We did not find any publications on MDRGN from Myanmar and Cambodia. We did not include publications related to Shigella spp., Salmonella spp., and Vibrio spp. and non-human related studies in our review. English language articles and abstracts were included for analysis. After the abstracts were reviewed, data on MDRGN in Southeast Asia from 54 publications were further reviewed and included in this study. Conclusions MDRGNs are a major contributor of antimicrobial-resistant bacteria in Southeast Asia. The high prevalence of ESBLs has been a major problem since 2005 and is possibly related to the development of carbapenem resistant organisms in this region due to the overuse of carbapenem therapy. Carbapenem–resistant Acinetobacter baumannii is the most common pathogen associated with nosocomial infections in this region followed by carbapenem-resistant Pseudomonas aeruginosa. Although Southeast Asia is not an endemic area for carbapenem-resistant Enterobacteriaceae (CRE, recently, the rate of CRE detection has been increasing. Limited infection control measures, lack of antimicrobial control, such as the presence of

New transposon tools tailored for metabolic engineering of Gram-negative microbial cell factories

Directory of Open Access Journals (Sweden)

Esteban eMartínez-García

2014-10-01

Full Text Available Re-programming microorganisms to modify their existing functions and/or to bestow bacteria with entirely new-to-Nature tasks have largely relied so far on specialized molecular biology tools. Such endeavors are not only relevant in the burgeoning metabolic engineering arena, but also instrumental to explore the functioning of complex regulatory networks from a fundamental point of view. À la carte modification of bacterial genomes thus calls for novel tools to make genetic manipulations easier. We propose the use of a series of new broad-host-range mini-Tn5 vectors, termed pBAMDs, for the delivery of gene(s into the chromosome of Gram-negative bacteria and for generating saturated mutagenesis libraries in gene function studies. These delivery vectors endow the user with the possibility of easy cloning and subsequent insertion of functional cargoes with three different antibiotic resistance markers (kanamycin, streptomycin, and gentamicin. After validating the pBAMD vectors in the environmental bacterium Pseudomonas putida KT2440, their use was also illustrated by inserting the entire poly(3-hydroxybutyrate (PHB synthesis pathway from Cupriavidus necator in the chromosome of a phosphotransacetylase mutant of Escherichia coli. PHB is a completely biodegradable polyester with a number of industrial applications that make it attractive as a potential replacement of oil-based plastics. The non-selective nature of chromosomal insertions of the biosynthetic genes was evidenced by a large landscape of PHB synthesis levels in independent clones. One clone was selected and further characterized as a microbial cell factory for PHB accumulation, and it achieved polymer accumulation levels comparable to those of a plasmid-bearing recombinant. Taken together, our results demonstrate that the new mini-Tn5 vectors can be used to confer interesting phenotypes in Gram-negative bacteria that would be very difficult to engineer through direct manipulation of the

New Transposon Tools Tailored for Metabolic Engineering of Gram-Negative Microbial Cell Factories

Energy Technology Data Exchange (ETDEWEB)

Martínez-García, Esteban; Aparicio, Tomás; Lorenzo, Víctor de; Nikel, Pablo I., E-mail: pablo.nikel@cnb.csic.es [Systems and Synthetic Biology Program, Centro Nacional de Biotecnología (CNB-CSIC), Madrid (Spain)

2014-10-28

Re-programming microorganisms to modify their existing functions and/or to bestow bacteria with entirely new-to-Nature tasks have largely relied so far on specialized molecular biology tools. Such endeavors are not only relevant in the burgeoning metabolic engineering arena but also instrumental to explore the functioning of complex regulatory networks from a fundamental point of view. À la carte modification of bacterial genomes thus calls for novel tools to make genetic manipulations easier. We propose the use of a series of new broad-host-range mini-Tn5-vectors, termed pBAMDs, for the delivery of gene(s) into the chromosome of Gram-negative bacteria and for generating saturated mutagenesis libraries in gene function studies. These delivery vectors endow the user with the possibility of easy cloning and subsequent insertion of functional cargoes with three different antibiotic-resistance markers (kanamycin, streptomycin, and gentamicin). After validating the pBAMD vectors in the environmental bacterium Pseudomonas putida KT2440, their use was also illustrated by inserting the entire poly(3-hydroxybutyrate) (PHB) synthesis pathway from Cupriavidus necator in the chromosome of a phosphotransacetylase mutant of Escherichia coli. PHB is a completely biodegradable polyester with a number of industrial applications that make it attractive as a potential replacement of oil-based plastics. The non-selective nature of chromosomal insertions of the biosynthetic genes was evidenced by a large landscape of PHB synthesis levels in independent clones. One clone was selected and further characterized as a microbial cell factory for PHB accumulation, and it achieved polymer accumulation levels comparable to those of a plasmid-bearing recombinant. Taken together, our results demonstrate that the new mini-Tn5-vectors can be used to confer interesting phenotypes in Gram-negative bacteria that would be very difficult to engineer through direct manipulation of the structural genes.

New Transposon Tools Tailored for Metabolic Engineering of Gram-Negative Microbial Cell Factories

International Nuclear Information System (INIS)

Martínez-García, Esteban; Aparicio, Tomás; Lorenzo, Víctor de; Nikel, Pablo I.

2014-01-01

Re-programming microorganisms to modify their existing functions and/or to bestow bacteria with entirely new-to-Nature tasks have largely relied so far on specialized molecular biology tools. Such endeavors are not only relevant in the burgeoning metabolic engineering arena but also instrumental to explore the functioning of complex regulatory networks from a fundamental point of view. À la carte modification of bacterial genomes thus calls for novel tools to make genetic manipulations easier. We propose the use of a series of new broad-host-range mini-Tn5-vectors, termed pBAMDs, for the delivery of gene(s) into the chromosome of Gram-negative bacteria and for generating saturated mutagenesis libraries in gene function studies. These delivery vectors endow the user with the possibility of easy cloning and subsequent insertion of functional cargoes with three different antibiotic-resistance markers (kanamycin, streptomycin, and gentamicin). After validating the pBAMD vectors in the environmental bacterium Pseudomonas putida KT2440, their use was also illustrated by inserting the entire poly(3-hydroxybutyrate) (PHB) synthesis pathway from Cupriavidus necator in the chromosome of a phosphotransacetylase mutant of Escherichia coli. PHB is a completely biodegradable polyester with a number of industrial applications that make it attractive as a potential replacement of oil-based plastics. The non-selective nature of chromosomal insertions of the biosynthetic genes was evidenced by a large landscape of PHB synthesis levels in independent clones. One clone was selected and further characterized as a microbial cell factory for PHB accumulation, and it achieved polymer accumulation levels comparable to those of a plasmid-bearing recombinant. Taken together, our results demonstrate that the new mini-Tn5-vectors can be used to confer interesting phenotypes in Gram-negative bacteria that would be very difficult to engineer through direct manipulation of the structural genes.

Phaeobacterium nitratireducens gen. nov., sp. nov., a phototrophic gammaproteobacterium isolated from a mangrove forest sediment sample

Digital Repository Service at National Institute of Oceanography (India)

Nupur, P.; Srinivas, T.N.R.; Takaichi, S.; AnilKumar, P.

A novel brown-coloured, Gram-negative-staining, rod-shaped, motile, phototrophic, purple sulfur bacterium, designated strain AK40^T , was isolated in pure culture from a sediment sample collected from Coringa mangrove forest, India. Strain...

Marinobacter nitratireducens sp. nov., a halophilic and lipolytic bacterium isolated from coastal surface sea water

Digital Repository Service at National Institute of Oceanography (India)

Bhumika, V.; Ravinder, K.; Korpole, S.; Srinivas, T.N.R.; AnilKumar, P.

A novel Gram-stain-negative, rod-shaped, motile bacterium, designated strain AK21^T , was isolated from coastal surface sea water at Visakhapatnam, India. The strain was positive for oxidase, catalase, lipase, L-proline arylamidase...

Controlling the aspect ratio of quantum dots: from columnar dots to quantum rods

NARCIS (Netherlands)

Li, L.; Patriarche, G.; Chauvin, N.J.G.; Ridha, P.; Rossetti, M.; Andrzejewski, J.; Sek, G.; Misiewicz, J.; Fiore, A.

2008-01-01

We demonstrate the feasibility and flexibility of artificial shape engineering of epitaxial semiconductor nanostructures. Novel nanostructures including InGaAs quantum rods (QRs), nanocandles, and quantum dots (QDs)-in-rods were realized on a GaAs substrate. They were formed by depositing a

High-Resolution Spore Coat Architecture and Assembly of Bacillus Spores

Energy Technology Data Exchange (ETDEWEB)

Malkin, A J; Elhadj, S; Plomp, M

2011-03-14

Elucidating the molecular architecture of bacterial and cellular surfaces and its structural dynamics is essential to understanding mechanisms of pathogenesis, immune response, physicochemical interactions, environmental resistance, and provide the means for identifying spore formulation and processing attributes. I will discuss the application of in vitro atomic force microscopy (AFM) for studies of high-resolution coat architecture and assembly of several Bacillus spore species. We have demonstrated that bacterial spore coat structures are phylogenetically and growth medium determined. We have proposed that strikingly different species-dependent coat structures of bacterial spore species are a consequence of sporulation media-dependent nucleation and crystallization mechanisms that regulate the assembly of the outer spore coat. Spore coat layers were found to exhibit screw dislocations and two-dimensional nuclei typically observed on inorganic and macromolecular crystals. This presents the first case of non-mineral crystal growth patterns being revealed for a biological organism, which provides an unexpected example of nature exploiting fundamental materials science mechanisms for the morphogenetic control of biological ultrastructures. We have discovered and validated, distinctive formulation-specific high-resolution structural spore coat and dimensional signatures of B. anthracis spores (Sterne strain) grown in different formulation condition. We further demonstrated that measurement of the dimensional characteristics of B. anthracis spores provides formulation classification and sample matching with high sensitivity and specificity. I will present data on the development of an AFM-based immunolabeling technique for the proteomic mapping of macromolecular structures on the B. anthracis surfaces. These studies demonstrate that AFM can probe microbial surface architecture, environmental dynamics and the life cycle of bacterial and cellular systems at near

On contact numbers in random rod packings

NARCIS (Netherlands)

Wouterse, A.; Luding, Stefan; Philipse, A.P.

2009-01-01

Random packings of non-spherical granular particles are simulated by combining mechanical contraction and molecular dynamics, to determine contact numbers as a function of density. Particle shapes are varied from spheres to thin rods. The observed contact numbers (and packing densities) agree well

[Microbial resistance to formaldehyde. I. Comparative quantitative studies in some selected species of vegetative bacteria, bacterial spores, fungi, bacteriophages and viruses].

Science.gov (United States)

Spicher, G; Peters, J

1976-12-01

The resistence of different microorganisms to formaldehyde was determined. As test objects served gram-negative and gram-positive vegetative germs (Klebsiella pneumoniae, Pseudomonas aeruginosa, Salmonella paratyphi-B, Staphylococcus aureus, Streptococcus faecalis), bacterial spores (Bacillus cereus, Bacillus pumilus, Bacillus stearothermophilus, Bacillus subtilis), fungi (Aspergillus niger, Candida albicans), bacteriophages (Escherichia coli phages, T1, T2, T3), and viruses (adenovirus, poliomyelitis virus, vaccinia virus). For the studies, suspensions of germs were exposed at identical temperature (20 degrees C) and pH (7.0). The microbicidal effect of formaldehyde was measured by the decrease of the proportion of germs capable of multiplication in the suspension (lg (N/N0); where: N0 equals initial number of germs capable of multiplication; N equals number of germs capable of multiplication after exposure to formaldehyde). For all germs the dependence of the microbicidal effect on the concentration of formaldehyde was determined. In all experiments, the duration of exposure was two hours. Pseudomonas aeruginosa, Klebsiella pneumoniae, and Salmonella paratyphi-B were found to be more susceptible than Staphylococcus aureus (vf. Fig. 1 A). The strains of Pseudomonas aeruginosa used were widely varying as to their susceptibility. To obtain equal microbicidal effects, concentrations of formaldehyde almost three times as high had to be used for the most resistant strain than were necessary for the most susceptible strain of Pseudomonas aeruginosa. All strains of Klebsiella pneumoniae examined were found to have an identical resistence to formaldehyde. Streptococcus faecalis was even more resistant to formaldehyde than Staphylococcus aureus. In the case of Streptococcus faecalis, a concentration of formaldehyde about three times as high had to be used to obtain microbicidal effects of identical magnitude. For the killing of Candida albicans cells concentrations of

Spatial and temporal distribution of Alternaria spores in the Iberian Peninsula atmosphere, and meteorological relationships: 1993-2009.

Science.gov (United States)

Aira, María-Jesús; Rodríguez-Rajo, Francisco-Javier; Fernández-González, María; Seijo, Carmen; Elvira-Rendueles, Belén; Abreu, Ilda; Gutiérrez-Bustillo, Montserrat; Pérez-Sánchez, Elena; Oliveira, Manuela; Recio, Marta; Tormo, Rafael; Morales, Julia

2013-03-01

This paper provides an updated of airborne Alternaria spore spatial and temporal distribution patterns in the Iberian Peninsula, using a common non-viable volumetric sampling method. The highest mean annual spore counts were recorded in Sevilla (39,418 spores), Mérida (33,744) and Málaga (12,947), while other sampling stations never exceeded 5,000. The same cities also recorded the highest mean daily spore counts (Sevilla 109 spores m(-3); Mérida 53 spores m(-3) and Málaga 35 spores m(-3)) and the highest number of days on which counts exceeded the threshold levels required to trigger allergy symptoms (Sevilla 38 % and Mérida 30 % of days). Analysis of annual spore distribution patterns revealed either one or two peaks, depending on the location and prevailing climate of sampling stations. For all stations, average temperature was the weather parameter displaying the strongest positive correlation with airborne spore counts, whilst negative correlations were found for rainfall and relative humidity.

Fertile organs and in situ spores of a new dipteridaceous fern Hausmannia sinensis from the Jurassic of northern China.

Science.gov (United States)

Wang, Yongdong; Zhang, Hong

2010-01-22

As a representative fossil member of the dipteridaceous fern, genus Hausmannia was reported worldwide from the Mesozoic strata; however, little is known about the fertile structures, including sporangia and in situ spores, of this genus. In this study, a new species Hausmannia sinensis was identified from the Middle Jurassic of Nei Mongol (Inner Mongolia), northern China. The specimens are compressions and are well preserved with details of sporangia and in situ spores. The leaf laminae are broadly fan-shaped, with an almost entire margin. Primary and lateral veins dichotomously branch to form square or polygonal meshes. Each ultimate mesh bears one to two circular sori of 0.4 mm in diameter. Sori are exindusiate; each sorus contains three to six round to ovoid sporangia. The annulus is developed and oblique, with stomial region present in proximal position. Spores are trilete, circular to oval in shape. Both proximal and distal surfaces are covered with baculate to subverrucate sculptures. Spores range from 20 to 30 microm in diameter (average 28 microm), and are comparable to the dispersed genera Baculatisporites Thomas and Pflug and Apiculatisporis Potonié and Kremp. Hausmannia sinensis represents the first compression species of genus Hausmannia form Eurasia, which shows the combination of well-preserved sori, sporangia, annuli and in situ spore characters, and is therefore helpful for further understanding the diversity and evolution of the Dipteridaceae fern lineage through time.

Antimicrobial effects of zero-valent iron nanoparticles on gram-positive Bacillus strains and gram-negative Escherichia coli strains

Directory of Open Access Journals (Sweden)

Yi-Huang Hsueh

2017-11-01

Full Text Available Abstract Background Zero-valent iron nanoparticles (ZVI NPs have been used extensively for the remediation of contaminated soil and groundwater. Owing to their large active surface area, they serve as strong and effective reductants. However, the ecotoxicity and bioavailability of ZVI NPs in diverse ecological media have not been evaluated in detail and most studies have focused on non-nano ZVI or Fe0. In addition, the antimicrobial properties of ZVI NPs have rarely been investigated, and the underlying mechanism of their toxicity remains unknown. Results In the present study, we demonstrate that ZVI NPs exhibited significant toxicity at 1000 ppm against two distinct gram-positive bacterial strains (Bacillus subtilis 3610 and Bacillus thuringiensis 407 but not against two gram-negative strains (Escherichia coli K12 and ATCC11634. Specifically, ZVI NPs caused at least a 4-log and 1-log reductions in cell numbers, respectively, in the two Bacillus strains, whereas no change was detected in the two E. coli strains. X-ray photoelectron spectroscopy, X-ray absorption near-edge, and extended X-ray absorption fine structure spectra confirmed that Bacillus cells exposed to ZVI NPs contained mostly Fe2O3 with some detectable FeS. This finding indicated that Fe0 nanoparticles penetrated the bacterial cells, where they were subsequently oxidized to Fe2O3 and FeS. RedoxSensor analysis and propidium iodide (PI staining showed decreased reductase activity and increased PI in both Bacillus strains treated with a high (1000 ppm concentration of ZVI NPs. Conclusion Taken together, these data show that the toxicity of ZVI NPs was derived from their oxidative properties, which may increase the levels of reactive oxygen species and lead to cell death.

新型包覆式双材质杆状EFP成型的数值仿真研究%Numerical simulation of new wrapping double-material rod-shaped EFP forming

Institute of Scientific and Technical Information of China (English)

黄松; 尹建平; 孙加肖

2017-01-01

In order to improve the damage to light armor at close range (4-5 times charge caliber),a kind of wrapping doublematerial liner was designed based on the damage mechanism of PELE.Using ANSYS/LS-DYNA software,the influence of the cone angle,the charge length-to-diameter ratio and the rate of liner thickness on EFP forming was studied based on the liner of large cone angle and variable-wall-thickness.The forming effect was compared and analyzed to obtain the optimal structure.The results show that charge length-to-diameter ratio is the main factor influencing the EFP velocity,cone angle is the main factor influencing the EFP length-to-diameter ratio.The shape of the EFP is preferable when the cone angle is about 149°,the charge length-to-diameter ratio is 0.8,the rate of liner thickness is about 10.0％,and the EFP steady speed is 2 598 m/s.Finally,the simulation on traditional single-material rod-shaped EFP and the new double-material rod-shaped EFP penetrating target was carried out.It is concluded that the new EFP can produce a lateral efficiency similar to PELE when penetrating target,which has greater damage ability to target than the single-material rod-shaped EFP.%为提高对近距离(4～5倍装药口径)轻型装甲的毁伤,基于PELE毁伤机理设计了一种包覆式双材质药型罩.运用ANSYS/LS-DYNA软件对大锥角变壁厚药型罩形成EFP进行数值仿真,研究药型罩锥角与装药长径比以及壁厚变化率对EFP成型的影响,对比分析其成型效果以得到较理想的侵彻体装药结构.结果表明:装药长径比是影响EFP速度的主要因素,锥角是影响EFP长径比的主要因素;药型罩锥角为149°左右、壁厚变化率为10.0％左右、装药长径比为0.8时可以形成较理想的杆状EFP,此时EFP的稳定速度约为2 598 m/s.最后通过传统单材质杆状EFP和该新型双材质杆状EFP侵彻靶板仿真,得出该新型包覆式双材质杆状EFP在侵彻靶板时能够产生类似PELE的横向效应,比单材质杆状EFP对靶板后部有更好的毁伤能力.

Genome sequence of Ensifer arboris strain LMG 14919T; a microsymbiont of the legume Prosopis chilensis growing in Kosti, Sudan

Science.gov (United States)

Reeve, Wayne; Tian, Rui; Bräu, Lambert; Goodwin, Lynne; Munk, Christine; Detter, Chris; Tapia, Roxanne; Han, Cliff; Liolios, Konstantinos; Huntemann, Marcel; Pati, Amrita; Woyke, Tanja; Mavrommatis, Konstantinos; Markowitz, Victor; Ivanova, Natalia; Kyrpides, Nikos; Willems, Anne

2013-01-01

Ensifer arboris LMG 14919T is an aerobic, motile, Gram-negative, non-spore-forming rod that can exist as a soil saprophyte or as a legume microsymbiont of several species of legume trees. LMG 14919T was isolated in 1987 from a nodule recovered from the roots of the tree Prosopis chilensis growing in Kosti, Sudan. LMG 14919T is highly effective at fixing nitrogen with P. chilensis (Chilean mesquite) and Acacia senegal (gum Arabic tree or gum acacia). LMG 14919T does not nodulate the tree Leucena leucocephala, nor the herbaceous species Macroptilium atropurpureum, Trifolium pratense, Medicago sativa, Lotus corniculatus and Galega orientalis. Here we describe the features of E. arboris LMG 14919T, together with genome sequence information and its annotation. The 6,850,303 bp high-quality-draft genome is arranged into 7 scaffolds of 12 contigs containing 6,461 protein-coding genes and 84 RNA-only encoding genes, and is one of 100 rhizobial genomes sequenced as part of the DOE Joint Genome Institute 2010 Genomic Encyclopedia for Bacteria and Archaea-Root Nodule Bacteria (GEBA-RNB) project. PMID:25197433

Genome sequence of Ensifer arboris strain LMG 14919(T); a microsymbiont of the legume Prosopis chilensis growing in Kosti, Sudan.

Science.gov (United States)

Reeve, Wayne; Tian, Rui; Bräu, Lambert; Goodwin, Lynne; Munk, Christine; Detter, Chris; Tapia, Roxanne; Han, Cliff; Liolios, Konstantinos; Huntemann, Marcel; Pati, Amrita; Woyke, Tanja; Mavrommatis, Konstantinos; Markowitz, Victor; Ivanova, Natalia; Kyrpides, Nikos; Willems, Anne

2014-06-15

Ensifer arboris LMG 14919(T) is an aerobic, motile, Gram-negative, non-spore-forming rod that can exist as a soil saprophyte or as a legume microsymbiont of several species of legume trees. LMG 14919(T) was isolated in 1987 from a nodule recovered from the roots of the tree Prosopis chilensis growing in Kosti, Sudan. LMG 14919(T) is highly effective at fixing nitrogen with P. chilensis (Chilean mesquite) and Acacia senegal (gum Arabic tree or gum acacia). LMG 14919(T) does not nodulate the tree Leucena leucocephala, nor the herbaceous species Macroptilium atropurpureum, Trifolium pratense, Medicago sativa, Lotus corniculatus and Galega orientalis. Here we describe the features of E. arboris LMG 14919(T), together with genome sequence information and its annotation. The 6,850,303 bp high-quality-draft genome is arranged into 7 scaffolds of 12 contigs containing 6,461 protein-coding genes and 84 RNA-only encoding genes, and is one of 100 rhizobial genomes sequenced as part of the DOE Joint Genome Institute 2010 Genomic Encyclopedia for Bacteria and Archaea-Root Nodule Bacteria (GEBA-RNB) project.

Genome sequence of the Lotus spp. microsymbiont Mesorhizobium loti strain R7A.

Science.gov (United States)

Kelly, Simon; Sullivan, John; Ronson, Clive; Tian, Rui; Bräu, Lambert; Munk, Christine; Goodwin, Lynne; Han, Cliff; Woyke, Tanja; Reddy, Tatiparthi; Huntemann, Marcel; Pati, Amrita; Mavromatis, Konstantinos; Markowitz, Victor; Ivanova, Natalia; Kyrpides, Nikos; Reeve, Wayne

2014-01-01

Mesorhizobium loti strain R7A was isolated in 1993 in Lammermoor, Otago, New Zealand from a Lotus corniculatus root nodule and is a reisolate of the inoculant strain ICMP3153 (NZP2238) used at the site. R7A is an aerobic, Gram-negative, non-spore-forming rod. The symbiotic genes in the strain are carried on a 502-kb integrative and conjugative element known as the symbiosis island or ICEMlSym(R7A). M. loti is the microsymbiont of the model legume Lotus japonicus and strain R7A has been used extensively in studies of the plant-microbe interaction. This report reveals that the genome of M. loti strain R7A does not harbor any plasmids and contains a single scaffold of size 6,529,530 bp which encodes 6,323 protein-coding genes and 75 RNA-only encoding genes. This rhizobial genome is one of 100 sequenced as part of the DOE Joint Genome Institute 2010 Genomic Encyclopedia for Bacteria and Archaea-Root Nodule Bacteria (GEBA-RNB) project.

The Effect of Charge at the Surface of Silver Nanoparticles on Antimicrobial Activity against Gram-Positive and Gram-Negative Bacteria: A Preliminary Study

International Nuclear Information System (INIS)

Abbaszadegan, A.; Ghahramani, Y.; Nabavizadeh, M.; Gholami, A.; Hemmateenejad, I.; Dorostkar, S.; Sharghi, H.

2014-01-01

The bactericidal efficiency of various positively and negatively charged silver nanoparticles has been extensively evaluated in literature, but there is no report on efficacy of neutrally charged silver nanoparticles. The goal of this study is to evaluate the role of electrical charge at the surface of silver nanoparticles on antibacterial activity against a panel of microorganisms. Three different silver nanoparticles were synthesized by different methods, providing three different electrical surface charges (positive, neutral, and negative). The antibacterial activity of these nanoparticles was tested against gram-positive (i.e., Staphylococcus aureus, Streptococcus mutans, and Streptococcus pyogenes) and gram-negative (i.e., Escherichia coli and Proteus vulgaris) bacteria. Well diffusion and micro-dilution tests were used to evaluate the bactericidal activity of the nanoparticles. According to the obtained results, the positively-charged silver nanoparticles showed the highest bactericidal activity against all microorganisms tested. The negatively charged silver nanoparticles had the least and the neutral nanoparticles had intermediate antibacterial activity. The most resistant bacteria were Proteus vulgaris. We found that the surface charge of the silver nanoparticles was a significant factor affecting bactericidal activity on these surfaces. Although the positively charged nanoparticles showed the highest level of effectiveness against the organisms tested, the neutrally charged particles were also potent against most bacterial species.

Photobacterium marinum sp. nov., a marine bacterium isolated from a sediment sample from Palk Bay, India

Digital Repository Service at National Institute of Oceanography (India)

Srinivas, T.N.R.; VijayaBhaskar, Y.; Bhumika, V.; AnilKumar, P.

The novel, cream colored, Gram-staining-negative, rod-shaped, motile bacteria, designated strains AK15 sup(T) and AK18, were isolated from sediment samples collected from Palk Bay, India. Both strains were positive for arginine dihydrolase, lysine...

Antibacterial activity of methylglyoxal against multi-drug resistant Salmonella Typhi

International Nuclear Information System (INIS)

Afzal, R.K.; Ahmed, A.

2018-01-01

To evaluate the antibacterial activity of MGO against MDR Salmonella typhi isolated from blood culture specimens and compare this activity against non-MDR S. typhi and with other gram negative rods. Study Design: Experimental study. Place and Duration of Study: Department of Microbiology, University of Health Sciences Lahore, from Jul 2011 to Jun 2012. Material and Methods: A total of 157 isolates of S. typhi were collected from different hospitals of Lahore and kept stored at -80 degree C. Morphological, biochemical and serological identification and antibiotic susceptibility testing of the isolates was carried out as per CLSI 2011 guidelines. Agar dilution method was used for the determination of MICs of MGO, using a multi-point inoculator. The data was compiled and results were determined using SPSS version 17. Results: Ninety-seven out of 157 isolates (61.8%) were MDR S. Typhi, while 60 (38.2%) were non-MDR S. Typhi. MIC90 of MGO against MDR S. Typhi isolates was (0.20 mg/mL; 2.8 mM), against non-MDR S. Typhi and Gram negative rods each, it was (0.21 mg/mL; 3.0 mM). When MICs of MGO against MDR S. Typhi group were compared to those of non-MDR S. Typhi group, the p-value was 0.827 (p>0.05; statistically insignificant). Whereas, the p-value of MICs of MGO against MDR S. Typhi group was 0.023 (p<0.05; statistically significant) when compared to gram negative rods group. Conclusion: MGO has good antibacterial activity against MDR and non-MDR S. Typhi, and other genera of Gram negative rods. (author)