Sample records for cephamycins

  1. Cephamycin inactivation due to enzymatic hydrolysis by beta-lactamase from Bacteroides fragilis.

    Yotsuji, A; Minami, S; Kakizawa, H; Yasuda, T; Takai, A.; Saikawa, I; Inoue, M.; Mitsuhashi, S


    The susceptibility of 53 clinical isolates of Bacteroides fragilis to cephamycins was examined. Judging from the MICs for 50% of the strains tested, moxalactam was the most active, however, judging from the MICs for 90% of the strains tested, cefbuperazone was more effective than moxalactam. A correlation was observed between in vitro activity of benzylpenicillin and cephaloridine and beta-lactamase production. Inactivation due to enzymatic hydrolysis of cephamycins over a short time was not ...

  2. Production of clavulanic acid and cephamycin C by Streptomyces clavuligerus under different fed-batch conditions

    C. Bellão


    Full Text Available The effect of carbon source and feeding conditions on the production of clavulanic acid (CA and cephamycin C (CephC by Streptomyces clavuligerus was investigated. In fed-batch experiments performed with glycerol feeding, production of CA exceeded that of CephC, and reached 1022 mg.L-1. Highest CephC production (566.5 mg.L-1 was obtained in fed-batch cultivation with glycerol feeding. In fed-batch experiments performed with starch feeding, the production of CephC was in general higher than that of CA. A dissociation index (DI was used to identify feeding conditions that favored production of CephC relative to CA. In all cultures with glycerol, DI values were less than unity, indicating higher production of CA compared to CephC. Conversely, in cultures fed with starch, the DI values obtained were greater than unity. However, no carbon source or feeding condition was able to completely dissociate the production of CA from that of CephC.

  3. Dissociation of cephamycin C and clavulanic acid biosynthesis by 1,3-diaminopropane in Streptomyces clavuligerus.

    Leite, Carla A; Cavallieri, André P; Baptista, Amanda S; Araujo, Maria L G C


    Streptomyces clavuligerus produces simultaneously cephamycin C (CephC) and clavulanic acid (CA). Adding 1,3-diaminopropane to culture medium stimulates production of beta-lactam antibiotics. However, there are no studies on the influence of this diamine on coordinated production of CephC and CA. This study indicates that 1,3-diaminopropane can dissociate CephC and CA productions. Results indicated that low diamine concentrations (below 1.25 g l(-1)) in culture medium increased CA production by 200%, but not that of CephC. Conversely, CephC production increased by 300% when 10 g l(-1) 1,3-diaminopropane was added to culture medium. Addition of just L-lysine (18.3 g l(-1)) to culture medium increased both biocompounds. On the other hand, while L-lysine plus 7.5 g l(-1) 1,3-diaminopropane increased volumetric production of CephC by 1100%, its impact on CA production was insignificant. The combined results suggest that extracellular concentration of 1,3-diaminopropane may trigger the dissociation of CephC and CA biosynthesis in S. clavuligerus. PMID:26564965

  4. Cefotetan, a new cephamycin: comparison of in vitro antimicrobial activity with other cephems, beta-lactamase stability, and preliminary recommendations for disk diffusion testing.

    Ayers, L W; Jones, R N; Barry, A. L.; Thornsberry, C; Fuchs, P C; Gavan, T L; Gerlach, E H; Sommers, H M


    Cefotetan is a new, potent, 7 alpha-methoxy cephalosporin (cephamycin). The in vitro activity of cefotetan tested in a multiphasic, collaborative study against 12,260 consecutive clinical isolates and 448 selected isolates showed 93% of Enterobacteriaceae, 90% of methicillin-susceptible Staphylococcus aureus (broth dilution), 83% of Bacteroides fragilis, and 72% of non-enterococcal streptococci to be inhibited by less than or equal to 8 micrograms/ml. Beta-Lactamase-producing and -nonproducin...

  5. Cefoxitin, a New Semi-synthetic Cephamycin: An In-vitro and In-vivo Comparison with Cephalothin

    Kosmidis, J.; Hamilton-Miller, J. M. T.; Gilchrist, J. N. G.; Kerry, D. W.; Brumfitt, W.


    The activity of cefoxitin was compared with that of cephalothin against 229 bacterial strains. Cefoxitin was more active against most Gram-negative strains, notably against indole-producing Proteus spp., which are usually resistant to the cephalosporins. Cefoxitin was not susceptible to any significant extent to degradation by β-lactamases produced by Gram-negative organisms. Against Gram-positive organisms, however, cefoxitin was considerably less active than cephalothin, but minimum inhibitory concentrations for Staphylococcus aureus were well within therapeutically attainable blood levels. Pharmacokinetic studies in 18 volunteers showed a higher and longer sustained antibiotic activity in serum and urine after injections of cefoxitin than after equal doses of cephalothin. Urinary recovery of cefoxitin activity was also much higher than that of cephalothin. No evidence of toxicity due to cefoxitin was found. Cefoxitin was slightly less painful after intramuscular injection than cephalothin. PMID:4202265

  6. Inhibitor-Sensitive AmpC β-Lactamase Variant Produced by an Escherichia coli Clinical Isolate Resistant to Oxyiminocephalosporins and Cephamycins

    Doi, Yohei; Wachino, Jun-ichi; Ishiguro, Masaji; Kurokawa, Hiroshi; Yamane, Kunikazu; Shibata, Naohiro; Shibayama, Keigo; Yokoyama, Keiko; Kato, Haru; Yagi, Tetsuya; Arakawa, Yoshichika


    Escherichia coli HKY28, a ceftazidime-resistant strain isolated from a urine specimen in Japan, produced an inhibitor-sensitive AmpC β-lactamase variant. The deduced amino acid sequence of the enzyme contained a number of substitutions and a tripeptide deletion (Gly286-Ser287-Asp288) compared with the sequence of native AmpC of E. coli. When the deletion was reverted by a 9-base insertion at the relevant site of ampC in the clone, the typical inhibitor-resistant phenotype of AmpC was restored...

  7. Animal and Human Multidrug-Resistant, Cephalosporin-Resistant Salmonella Isolates Expressing a Plasmid-Mediated CMY-2 AmpC β-Lactamase

    Winokur, P. L.; Brueggemann, A.; DeSalvo, D. L.; Hoffmann, L.; Apley, M. D.; Uhlenhopp, E. K.; Pfaller, M A; Doern, G. V.


    Salmonella spp. are important food-borne pathogens that are demonstrating increasing antimicrobial resistance rates in isolates obtained from food animals and humans. In this study, 10 multidrug-resistant, cephalosporin-resistant Salmonella isolates from bovine, porcine, and human sources from a single geographic region were identified. All isolates demonstrated resistance to cephamycins and extended-spectrum cephalosporins as well as tetracycline, chloramphenicol, streptomycin, and sulfisoxa...

  8. In vitro activity of cefmetazole, cefotetan, amoxicillin-clavulanic acid, and other antimicrobial agents against anaerobic bacteria from endometrial cultures of women with pelvic infections.

    Ohm-Smith, M J; Sweet, R. L.


    The MICs of the new antimicrobial agents cefmetazole, cefotetan, and amoxicillin-clauvulanic acid were compared with the MICs of other antimicrobial agents against anaerobic bacteria from endometrial cultures from women with pelvic inflammatory disease or endometritis. The activity of cefmetazole was similar to that of cefoxitin and generally greater than that of cefotetan. Amoxicillin-clavulanic acid was generally more active than all cephamycins tested.

  9. TEM-4, a new plasmid-mediated beta-lactamase that hydrolyzes broad-spectrum cephalosporins in a clinical isolate of Escherichia coli.

    Paul, G C; Gerbaud, G; Bure, A; Philippon, A M; B. Pangon; Courvalin, P.


    A clinical isolate of Escherichia coli, strain CB-134, recovered in 1986 from an abdominal abscess, exhibited resistance to penams, oxyimino-beta-lactams including broad-spectrum cephalosporins (cefotaxime, ceftriaxone, ceftazidime), and aztreonam but remained susceptible to cephamycins (cefoxitin, cefotetan) and to moxalactam and imipenem. Clavulanate (2 micrograms/ml) restored the susceptibility of the strain to broad-spectrum cephalosporins and aztreonam. A beta-lactamase with an isoelectr...

  10. In Vivo Selection of a Chromosomally Encoded β-Lactamase Variant Conferring Ceftazidime Resistance in Klebsiella oxytoca

    Mammeri, Hedi; Poirel, Laurent; Nordmann, Patrice


    Klebsiella oxytoca clinical isolate A was recovered from the urine of a 55-year-old man with prostatic and urinary tract infections. This isolate displayed a β-lactam resistance phenotype consistent with overproduction of a chromosomally encoded class A β-lactamase and had decreased susceptibilities to all β-lactams except ceftazidime, cephamycins, and carbapenems. Four weeks after treatment with an antibiotic regimen that included ceftazidime, K. oxytoca isolate B, which had a high level of ...

  11. Frequency and Antibiotic Susceptibility Pattern of Amp C Beta Lactamase Producing Bacteria Isolated from a Tertiary Care Hospital of Pakistan

    Afreenish Hassan; Javaid Usman; Fatima Kaleem; Maria Omair; Ali Khalid; Muhammad Iqabal


    Objective: Amp C beta lactamases are cephalosporinases which hydrolyze cephamycins and are poorlyinhibited by clavulanic acid. Amp C beta lactamases confer resistance to a wide variety of antibiotics andpose both diagnostic and therapeutic challenges, The objective was to detect the frequency and antibioticsusceptibility pattern of Amp C beta lactamase producing bacteria isolated from a tertiary care hospital ofPakistan.Methodology: Organisms were isolated from various clinical specimens. Fir...

  12. Nucleotide Sequence of the Chromosomal ampC Gene of Enterobacter aerogenes

    Preston, Karen E.; Radomski, Christopher C. A.; Venezia, Richard A.


    The AmpC β-lactamase gene and a small portion of the regulatory ampR sequence of Enterobacter aerogenes 97B were cloned and sequenced. The β-lactamase had an isoelectric point of 8 and conferred cephalosporin and cephamycin resistance on the host. The sequence of the cloned gene is most closely related to those of the ampC genes of E. cloacae and C. freundii.

  13. Ampc Beta Lactamases Among Gram Negative Clinical Isolates From A Tertiary Hospital, South India

    Mohamudha, Parveen R.; Harish, B. N.; S C Parija


    AmpC β-lactamases are cephalosporinases that hydrolyze cephamycins as well as other extended-spectrum cephalosporins and are poorly inhibited by clavulanic acid. Although reported with increasing frequency, the true rate of occurrence of AmpC β-lactamases in different organisms, including members of Enterobacteriaceae, remains unknown. The present study was designed to determine the occurrence of AmpC enzyme-harbouring Gram-negative clinical isolates in a tertiary care hospital in P...

  14. Natural Variants of the KPC-2 Carbapenemase have Evolved Increased Catalytic Efficiency for Ceftazidime Hydrolysis at the Cost of Enzyme Stability

    Mehta, Shrenik C.; Rice, Kacie; Palzkill, Timothy


    The spread of β-lactamases that hydrolyze penicillins, cephalosporins and carbapenems among Gram-negative bacteria has limited options for treating bacterial infections. Initially, Klebsiella pneumoniae carbapenemase-2 (KPC-2) emerged as a widespread carbapenem hydrolyzing β-lactamase that also hydrolyzes penicillins and cephalosporins but not cephamycins and ceftazidime. In recent years, single and double amino acid substitution variants of KPC-2 have emerged among clinical isolates that sho...

  15. Natural Variants of the KPC-2 Carbapenemase have Evolved Increased Catalytic Efficiency for Ceftazidime Hydrolysis at the Cost of Enzyme Stability.

    Mehta, Shrenik C.; Kacie Rice; Timothy Palzkill


    The spread of β-lactamases that hydrolyze penicillins, cephalosporins and carbapenems among Gram-negative bacteria has limited options for treating bacterial infections. Initially, Klebsiella pneumoniae carbapenemase-2 (KPC-2) emerged as a widespread carbapenem hydrolyzing β-lactamase that also hydrolyzes penicillins and cephalosporins but not cephamycins and ceftazidime. In recent years, single and double amino acid substitution variants of KPC-2 have emerged among clinical isolates that sho...

  16. In Vitro Activities of Cefminox against Anaerobic Bacteria Compared with Those of Nine Other Compounds

    Hoellman, Dianne B.; Spangler, Sheila K.; Jacobs, Michael R.; Appelbaum, Peter C.


    The agar dilution MIC method was used to test the activity of cefminox, a β-lactamase-stable cephamycin, compared with those of cefoxitin, cefotetan, moxalactam, ceftizoxime, cefotiam, cefamandole, cefoperazone, clindamycin, and metronidazole against 357 anaerobes. Overall, cefminox was the most active β-lactam, with an MIC at which 50% of isolates are inhibited (MIC50) of 1.0 μg/ml and an MIC90 of 16.0 μg/ml. Other β-lactams were less active, with respective MIC50s and MIC90s of 2.0 and 64.0...

  17. Characterization of SFO-1, a Plasmid-Mediated Inducible Class A β-Lactamase from Enterobacter cloacae

    Matsumoto, Yoshimi; Inoue, Matsuhisa


    Enterobacter cloacae 8009 produced an inducible class A β-lactamase which hydrolyzed cefotaxime efficiently. It also hydrolyzed other β-lactams except cephamycins and carbapenems. The activity was inhibited by clavulanic acid and imipenem. The bla gene was transferable to Escherichia coli by electroporation of plasmid DNA. The molecular mass of the β-lactamase was 29 kDa and its pI was 7.3. All of these phenotypic characteristics of the enzyme except for inducible production resemble those of...

  18. Evidence for Transfer of CMY-2 AmpC β-Lactamase Plasmids between Escherichia coli and Salmonella Isolates from Food Animals and Humans

    Winokur, P. L.; Vonstein, D. L.; Hoffman, L J; Uhlenhopp, E. K.; Doern, G. V.


    Escherichia coli is an important pathogen that shows increasing antimicrobial resistance in isolates from both animals and humans. Our laboratory recently described Salmonella isolates from food animals and humans that expressed an identical plasmid-mediated, AmpC-like β-lactamase, CMY-2. In the present study, 59 of 377 E. coli isolates from cattle and swine (15.6%) and 6 of 1,017 (0.6%) isolates of human E. coli from the same geographic region were resistant to both cephamycins and extended-...

  19. Cefoxitin and Cephalothin: Antimicrobial Activity, Human Pharmacokinetics, and Toxicology

    Brumfitt, William; Kosmidis, John; Hamilton-Miller, Jeremy M. T.; Gilchrist, James N. G.


    Cefoxitin, a semisynthetic cephamycin, has been compared with the widely used parenteral cephalosporin, cephalothin, in terms of antibacterial activity, human pharmacokinetics, and toxicity. For both compounds, minimal inhibitory concentrations were within the therapeutic range against the 156 gram-positive cocci tested (except group D streptococci), but cephalothin was 8 to 20 times more active. Regarding the 313 gram-negative organisms tested, both antibiotics were of approximately equal activity against cephalothin-susceptible strains, but cefoxitin was outstandingly superior against Providencia spp. and indole-producing Proteus spp., and markedly better against Serratia marcescens and Bacteroides fragilis. Against these organisms, cefoxitin but not cephalothin would be expected to be therapeutically valuable. Antibiotic activity levels in the serum and urine of 18 human volunteers after parenteral administration were higher and more prolonged in the case of cefoxitin, which had an average terminal serum half-life of about 45 min and a urinary recovery of about 90%. Cefoxitin was entirely nontoxic and, given intramuscularly, slightly less painful then cephalothin. These preliminary results suggest that cephamycins may prove to be a significant chemotherapeutic advance. PMID:15830475

  20. [In vitro activity of meropenem and seven other beta-lactam antibiotics against K.pneumoniae and enterobacteriaceae producing beta-lactamases with extended spectrum].

    Cavallo, J D; Fabre, R; Crenn, Y; Meyran, M


    Meropenem is a broad antibacterial spectrum carbapenem with a good activity on betalactam resistant Gram-negative bacilli. 120 non repetitive strains isolated from clinical samples from 1989 to 1992 were selected: 60 K. pneumoniae, 7 E. coli, 2 E. aerogenes and 1 S. marcescens with extended spectrum betalactamases (23 CTX-1, 18 SHV-2, 5 SHV-3, 16 SHV-4, 4 SHV-5, 3 CTX-1 + SHV-4, 1 CAZ-1), 10 K. pneumoniae with broad spectrum TEM-1 enzyme, and 40 K. pneumoniae with only SHV-1 chromosomal betalactamase. Determination of Minimal inhibitory concentrations (MIC) was done by agar dilution method for meropenem and 7 other betalactams (amoxicillin + clavulanic acid 2 mg/l, piperacillin + tazobactam 4 mg/l, cefoxitin, cefotetan, cefotaxime, ceftazidime, imipenem). All antibiotics except amoxicillin + clavulanic acid are active against strains with constitutive penicillinase. For strains with TEM-1 penicillinase, cephamycins, third generation cephalosporins and carbapenems are active. For strains with different extended spectrum betalactamases only cephamycins and carbapenems are efficious. There is no difference according to the period of isolation: 1989-90 or 1991-92. Meropenem has the best in vitro activity (MIC50 = 0.03 mg/l) for all strains independently of the nature of betalactamase. PMID:7824297

  1. Extended-spectrum plasmid-mediated beta-lactamases.

    Sirot, D


    Extended-spectrum beta-lactamases (ESBLs) are mutant enzymes which derive from TEM or SHV (class A) enzymes. They confer variable levels of resistance to cefotaxime, ceftazidime and other broad-spectrum cephalosporins and to monobactams such as aztreonam but have no detectable activity against cephamycins and carbapenems. Recently, new plasmid-mediated ESBLs, not derived from TEM or SHV enzymes but related to cephalosporinases of Enterobacteriaceae (class C enzymes), that confer resistance to all cephalosporins including cephamycins, have been reported. However, to date there have been no reported outbreaks due to strains producing transferable cephalosporinases. Klebsiella pneumoniae is the species in which the ESBL enzymes have been most commonly reported around the world. Most of the clinical isolates that produce TEM- or SHV-derived ESBL, come from hospitalised patients and have frequently caused nosocomial outbreaks. Care should be taken in the selection of a beta-lactam for the treatment of infections because the presence of an ESBL does not prevent other mechanisms of resistance, such as decreased permeability, from emerging. Broad-spectrum cephalosporins including cefepime and cefpirome are hydrolysed by ESBL. However, low level resistance to cefotaxime, ceftriaxone, cefepime and aztreonam does occur in some strains producing certain TEM-derived ESBL. It remains to be seen, therefore, whether such isolates are clinically susceptible to these drugs. The combination of a third-generation cephalosporin and a beta-lactamase inhibitor such as sulbactam could be of interest against some strains producing certain ESBLs. Among the 7-alpha-methoxy cephalosporins, cefotetan and latamoxef are the most active. However, cephamycins should be used with caution to treat infections caused by ESBL-producing K. pneumoniae because of the relative ease with which clinical strains decrease the expression of outer membrane proteins. The most active beta-lactams are the

  2. Detection of CMY-2 AmpC β-lactamase-producing enterohemorrhagic Escherichia coli O157:H7 from outbreak strains in a nursery school in Japan.

    Kameyama, Mitsuhiro; Yabata, Junko; Nomura, Yasuharu; Tominaga, Kiyoshi


    In 2013, an outbreak of enterohemorrhagic Escherichia coli (EHEC) O157:H7 occurred in a nursery school in Japan. The outbreak affected 12 school children and five members of their families. All 17 isolates obtained from these individuals were found to be clonal, as determined by pulsed-field gel electrophoresis analysis and multilocus variable number tandem repeat analysis. The antimicrobial susceptibility profiles of the isolates to 20 drugs were examined, with three isolates showing resistance to the extended-spectrum cephalosporins (ESC) and cephamycin, including cefotaxime, ceftazidime, and cefminox. The resistant isolates carried the blaCMY-2 AmpC β-lactamase gene. It is proposed that the ESC-resistant EHEC O157:H7 isolates might have acquired the resistance plasmid encoding the blaCMY-2 gene during human to human infection in the nursery school. PMID:25835518

  3. [Properties of a cephalosporinase produced by Proteus penneri inhibited by clavulanic acid].

    Miro, E; Barthelemy, M; Peduzzi, J; Reynaud, A; Morand, A; Prats, G; Labia, R


    P. penneri produces an inducible cephalosporinase, as many Enterobacteriaceae. Nevertheless this betalactamase is susceptible to clavulanic acid which is an exception also encountered for P. vulgaris. The authors studied the enzyme produced by P. penneri 14HBC resistant to cefotaxime (MIC 16 mg/l) isolated in Spain in 1992. This betalactamase of isoelectric point 6.65 hydrolyzes first generation cephalosporins, amoxycillin and poorly ticarcillin as it occurs for all cephalosporinases. However, this enzyme hydrolyzes strongly oxyimino-cephalosporins: cefuroxime, cefotaxime, cefepime, cefpirome as it occurs with extended-spectrum betalactamases. Cephamycins and imipenem are not substrates. Clavulanic acid has a very good affinity for this betalactamase which is inactivated progressively. These properties are similar to those of the enzyme of P. vulgaris Ro104 of isoelectric point 8.3 which, contrarily to other cephalosporinases, belongs to the structural Ambler's class A. PMID:7824319

  4. [2d-generation cephalosporins in the treatment of gram-negative superinfections].

    Mouton, Y; Caillaux, M; Brion, M; Fourrier, A


    The second generation cephalosporins are those drugs that are totally or partially resistant to betalactamases (cefamandole, cefuroxime) or the cephamycins (cefoxitine). This property allows them to destroy the enterobacteria resistant to cefalotine and they may have a place in the treatment of certain post-operative infections (abdominal, gynaecological, urinary) on their own or in combination with an aminoglycoside. They also may be of use in combination with an aminoglycoside in the management of secondary septicaemia infections. Outside of these indications which are dependent on the bacteriological findings, their use should be limited even when there is an absence of organisms that are Cefalotine sensitive on the antibiogram. This careful approach (which applies particularly for cefotaxine) may be abandoned once a certain quantity of resistant strains have emerged. For the time being, the second generation cephalosporins ought to be used only for specific indications, and as a general rule should not be first line antibiotic treatment. PMID:44971

  5. The Mechanisms of Catalysis by Metallo -Lactamases

    Michael I. Page


    Full Text Available Class B -lactamases or metallo--lactamases (MBLs require zinc ions to catalyse the hydrolysis of -lactam antibiotics such as penicillins, cephalosporins, carbapenems, and cephamycins. There are no clinically useful inhibitors against MBLs which are responsible for the resistance of some bacteria to antibiotics. There are two metal-ion binding sites that have different zinc ligands but the exact roles of the metal-ion remain controversial, and distinguishing between their relative importance is complex. The metal-ion can act as a Lewis acid by co-ordination to the -lactam carbonyl oxygen to facilitate nucleophilic attack and stabilise the negative charge developed on this oxygen in the tetrahedral intermediate anion. The metal-ion also lowers the pKa of the directly co-ordinated water molecule so that the metal-bound hydroxide ion is a better nucleophile than water and is used to attack the -lactam carbonyl carbon. An intrinsic property of binuclear metallo hydrolytic enzymes that depend on a metal-bound water both as the attacking nucleophile and as a ligand for the second metal-ion is that this water molecule, which is consumed during hydrolysis of the substrate, has to be replaced to maintain the catalytic cycle. With MBL this is reflected in some unusual kinetic profiles.




    Full Text Available Resistant to antimicrobial agents in microbes is a growing phenomenon worldwide. 1 β lactamase production is the most common mechanism of bacterial resistance to β lactam antibiotics. 2 Extended spectrum beta lactamases (ESBL that mediate resistance to oxyimino cephalosporins such as cefotaxime, ceftazidime and aztreonam are now observed in all species of Enterobacteriaceae. ESBL are capable of efficiently hydrolyzing penicillins, narro w spectrum cephalosporins, many extended spectrum cephalosporins, the oxyimino group containing cephalosporins ( C efotaxime, ceftazidime and monobactams ( A ztreonam, but not carbapenems and cephamycins. 3 ESBL producing Ecoli and Klebsiella pneumoniae are important pathogen in nosocomial infections and multidrug resistant out breaks. This study was conducted to correlate results of Double Disc Synergy Test (DDST and E test for ESBL detection in E coli and Klebsiella pneumoniae isolate by doing the double d isc synergy test (DDST by using cefotaxime and augmemtin discs. E test was used to determine the MIC for cefotaxime and ceftazidime of these isolates. Out of 98 ESBL isolates detected by DDST, 96 isolates were positive by E test. 02 isolates were indeterminable by E test. About 95% ESBL producing E coli and Klebsiella pneumoniae had MIC >1ug/ml for cefotaxime. The MIC of about 85% ESBL producing E coli and Klebsiella pneumonia was >4ug/ml for ceftazidime.

  7. In vivo selection of a chromosomally encoded beta-lactamase variant conferring ceftazidime resistance in Klebsiella oxytoca.

    Mammeri, Hedi; Poirel, Laurent; Nordmann, Patrice


    Klebsiella oxytoca clinical isolate A was recovered from the urine of a 55-year-old man with prostatic and urinary tract infections. This isolate displayed a beta-lactam resistance phenotype consistent with overproduction of a chromosomally encoded class A beta-lactamase and had decreased susceptibilities to all beta-lactams except ceftazidime, cephamycins, and carbapenems. Four weeks after treatment with an antibiotic regimen that included ceftazidime, K. oxytoca isolate B, which had a high level of resistance to ceftazidime, was isolated from the urine of the same patient. Isoelectric focusing analysis of the culture extracts of these isolates gave a pI of 5.4 for both isolates. Cloning experiments with the PCR products of the bla(OXY) gene resulted in two Escherichia coli DH10B recombinant clones with resistance phenotypes mirroring those of the parental isolates. Sequencing analysis revealed that the bla(OXY-2-5) gene from K. oxytoca B had a single nucleotide substitution compared to the sequence of the bla(OXY-2) gene from K. oxytoca A, leading to a proline-to-serine substitution at position 167, according to the numbering of Ambler. Biochemical analysis of purified OXY-2-5 showed that it had the ability to hydrolyze ceftazidime. This is the first report of in vivo selection of a K. oxytoca isolate that produced a chromosomally encoded beta-lactamase conferring resistance to ceftazidime. PMID:14638475

  8. Determination of thermodynamic parameters of benzylpenicillin hydrolysis by metallo-β-lactamase CcrA from Bacteroides fragilis

    Zhai, Le; Zhou, Li-Sheng; Liu, Cheng-Cheng; Shi, Ying; Zhou, Ya-Jun [Key Laboratory of Synthetic and Natural Functional Molecule Chemistry of Ministry of Education, College of Chemistry and Materials Science, Northwest University, Xi’an 710069 (China); Yang, Ke-Wu, E-mail: [Key Laboratory of Synthetic and Natural Functional Molecule Chemistry of Ministry of Education, College of Chemistry and Materials Science, Northwest University, Xi’an 710069 (China)


    Highlights: ► First report the thermokinetic parameters of benzylpenicillin hydrolysis with CcrA. ► The hydrolysis is a spontaneous and exothermic reaction with order of 1.4. ► Summarized that CcrA prefer to hydrolyze penicillins among β-lactam antibiotics. - Abstract: One of the most common way that bacteria become resistant to antibiotics is by the production of metallo-β-lactamases (MβLs) to hydrolyze the β-lactam-containing antibiotics. In this paper, the thermodynamic parameters of benzylpenicillin hydrolysis with B1 subclasses MβL CcrA (carbapenem and cephamycin resistance) from Bacteroides fragilis were determined by microcalorimetry. The activation free energy ΔG{sub ≠}{sup θ} is 87.90 ± 0.03, 88.99 ± 0.01, 89.93 ± 0.04 and 90.93 ± 0.05 kJ mol{sup −1} at 293.15, 298.15, 303.15 and 308.15 K, activation enthalpy ΔH{sub ≠}{sup θ} is 29.21 ± 0.03 kJ mol{sup −1}, activation entropy ΔS{sub ≠}{sup θ} is −200.34 ± 0.08 J mol{sup −1} K{sup −1}, the reaction order is 1.4, and the apparent activation energy E is 31.71 kJ mol{sup −1}. The thermodynamic characterization indicated that CcrA prefer to hydrolyze penicillins among three kinds of β-lactam-containing antibiotics.

  9. Characterization of SFO-1, a plasmid-mediated inducible class A beta-lactamase from Enterobacter cloacae.

    Matsumoto, Y; Inoue, M


    Enterobacter cloacae 8009 produced an inducible class A beta-lactamase which hydrolyzed cefotaxime efficiently. It also hydrolyzed other beta-lactams except cephamycins and carbapenems. The activity was inhibited by clavulanic acid and imipenem. The bla gene was transferable to Escherichia coli by electroporation of plasmid DNA. The molecular mass of the beta-lactamase was 29 kDa and its pI was 7.3. All of these phenotypic characteristics of the enzyme except for inducible production resemble those of some extended-spectrum class A beta-lactamases like FEC-1. The gene encoding this beta-lactamase was cloned and sequenced. The deduced amino acid sequence of the beta-lactamase was homologous to the AmpA sequences of the Serratia fonticola chromosomal enzyme (96%), MEN-1 (78%), Klebsiella oxytoca chromosomal enzymes (77%), TOHO-1 (75%), and FEC-1 (72%). The conserved sequences of class A beta-lactamases, including the S-X(T)-X(S)-K motif, in the active site were all conserved in this enzyme. On the basis of the high degree of homology to the beta-lactamase of S. fonticola, the enzyme was named SFO-1. The ampR gene was located upstream of the ampA gene, and the AmpR sequence of SFO-1 had homology with the AmpR sequences of the chromosomal beta-lactamases from Citrobacter diversus (80%), Proteus vulgaris (68%), and Pseudomonas aeruginosa (60%). SFO-1 was also inducible in E. coli. However, a transformant harboring plasmid without intact ampR produced a small amount of beta-lactamase constitutively, suggesting that AmpR works as an activator of ampA of SFO-1. This is the first report from Japan describing an inducible plasmid-mediated class A beta-lactamase in gram-negative bacteria. PMID:9925524

  10. Extended-spectrum beta-lactamases: implications for the clinical laboratory and therapy.

    Harada, Sohei; Ishii, Yoshikazu; Yamaguchi, Keizo


    Production of extended-spectrum beta-lactamase (ESBL) is one of the most important resistance mechanisms that hamper the antimicrobial treatment of infections caused by Enterobacteriaceae. ESBLs are classified into several groups according to their amino-acid sequence homology. While TEM and SHV enzymes were the most common ESBLs in the 1990s, CTX-M enzymes have spread rapidly among Enterobacteriaceae in the past decade. In addition, some epidemiological studies showed that organisms producing CTX-M enzymes had become increasingly prevalent in the community setting in certain areas in the world. Several novel enzymes with hydrolyzing activity against oxyimino-cephalosporins, albeit with additional enzymatic characteristics different from those of original TEM and SHV ESBLs (e.g., inhibitor-resistance), have been discovered and pose a problem on the definition of ESBLs. Although several methods to detect the production of ESBL are available in clinical laboratories, existence of other factors contributing resistance against beta-lactams, e.g., inducible production of Amp-C beta-lactamase by some species of Enterobacteriaceae, or inhibitor-resistance in some ESBLs may hinder the detection of ESBLs with these methods. Carbapenems are stable against hydrolyzing activity of ESBLs and are regarded as the drug of choice for the treatment of infections caused by ESBL-producing Enterobacteriaceae. Although several other antimicrobial agents, such as fluoroquinolones and cephamycins, may have some role in the treatment of mild infections due to those organisms, clinical data that warrant the use of antimicrobial agents other than carbapenems in the treatment of serious infections due to those organisms are scarce for now. PMID:19127103

  11. Natural Variants of the KPC-2 Carbapenemase have Evolved Increased Catalytic Efficiency for Ceftazidime Hydrolysis at the Cost of Enzyme Stability.

    Shrenik C Mehta


    Full Text Available The spread of β-lactamases that hydrolyze penicillins, cephalosporins and carbapenems among Gram-negative bacteria has limited options for treating bacterial infections. Initially, Klebsiella pneumoniae carbapenemase-2 (KPC-2 emerged as a widespread carbapenem hydrolyzing β-lactamase that also hydrolyzes penicillins and cephalosporins but not cephamycins and ceftazidime. In recent years, single and double amino acid substitution variants of KPC-2 have emerged among clinical isolates that show increased resistance to ceftazidime. Because it confers multi-drug resistance, KPC β-lactamase is a threat to public health. In this study, the evolution of KPC-2 function was determined in nine clinically isolated variants by examining the effects of the substitutions on enzyme kinetic parameters, protein stability and antibiotic resistance profile. The results indicate that the amino acid substitutions associated with KPC-2 natural variants lead to increased catalytic efficiency for ceftazidime hydrolysis and a consequent increase in ceftazidime resistance. Single substitutions lead to modest increases in catalytic activity while the double mutants exhibit significantly increased ceftazidime hydrolysis and resistance levels. The P104R, V240G and H274Y substitutions in single and double mutant combinations lead to the largest increases in ceftazidime hydrolysis and resistance. Molecular modeling suggests that the P104R and H274Y mutations could facilitate ceftazidime hydrolysis through increased hydrogen bonding interactions with the substrate while the V240G substitution may enhance backbone flexibility so that larger substrates might be accommodated in the active site. Additionally, we observed a strong correlation between gain of catalytic function for ceftazidime hydrolysis and loss of enzyme stability, which is in agreement with the 'stability-function tradeoff' phenomenon. The high Tm of KPC-2 (66.5°C provides an evolutionary advantage as

  12. Analysis of the use of antimicrobial agents and the monitoring of bacterial resistance%2011-2013年我院抗菌药物使用与细菌耐药性监测的分析

    宋桂芳; 王韵


    Objective:To analyze relevance between the DDDs of antimicrobial agents and the drug resistance of common clinical pathogens in our hospital during 2011-2013 so as to provide a basis for guiding rational drug use. Methods:The number of consumption of antimicrobial agents and the incidence of major drug resistant pathogens were statistically analyzed and the related data were compared. Results:The DDDs of the third generation of cephalosporins, cephamycins, carbapenems and macrolides showed an upward trend, and the rates of drug resistance of main bacteria such as Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa Bowman/hemolytic Acinetobacter, Staphylococcus aureus and so on also showed an increasing trend. Conclusion:The DDDs of antimicrobial agents and bacterial resistance are closely related and therefore the management of antimicrobial agents should be further strengthened and improved and great attention should be paid to the monitoring of bacterial resistance.%目的:分析我院抗菌药物用药频度及与临床常见致病菌耐药情况的关联性,为指导合理用药提供依据。方法:对本院2011-2013年抗菌药物消耗数量进行统计分析,并对主要致病菌的耐药率进行统计,分析比较相关数据。结果:三代头孢菌素、头霉素类、碳青霉烯类和大环内酯类的DDDs呈上升趋势,主要致病菌大肠埃希氏菌、肺炎克雷伯氏菌、铜绿假单胞菌、鲍曼/溶血不动杆菌、金黄色葡萄球菌等的耐药率也呈逐年上升的趋势。结论:抗菌药物的DDDs对细菌耐药率关联性高,医院需要进一步加强和完善抗菌药物的管理,对细菌耐药率监测应高度重视。

  13. Characterization of VIM-2, a carbapenem-hydrolyzing metallo-beta-lactamase and its plasmid- and integron-borne gene from a Pseudomonas aeruginosa clinical isolate in France.

    Poirel, L; Naas, T; Nicolas, D; Collet, L; Bellais, S; Cavallo, J D; Nordmann, P


    Pseudomonas aeruginosa COL-1 was identified in a blood culture of a 39-year-old-woman treated with imipenem in Marseilles, France, in 1996. This strain was resistant to beta-lactams, including ureidopenicillins, ticarcillin-clavulanic acid, cefepime, ceftazidime, imipenem, and meropenem, but remained susceptible to the monobactam aztreonam. The carbapenem-hydrolyzing beta-lactamase gene of P. aeruginosa COL-1 was cloned, sequenced, and expressed in Escherichia coli DH10B. The deduced 266-amino-acid protein was an Ambler class B beta-lactamase, with amino acid identities of 32% with B-II from Bacillus cereus; 31% with IMP-1 from several gram-negative rods in Japan, including P. aeruginosa; 27% with CcrA from Bacteroides fragilis; 24% with BlaB from Chryseobacterium meningosepticum; 24% with IND-1 from Chryseobacterium indologenes; 21% with CphA-1 from Aeromonas hydrophila; and 11% with L-1 from Stenotrophomonas maltophilia. It was most closely related to VIM-1 beta-lactamase recently reported from Italian P. aeruginosa clinical isolates (90% amino acid identity). Purified VIM-2 beta-lactamase had a pI of 5.6, a relative molecular mass of 29.7 kDa, and a broad substrate hydrolysis range, including penicillins, cephalosporins, cephamycins, oxacephamycins, and carbapenems, but not monobactams. As a metallo-beta-lactamase, its activity was zinc dependent and inhibited by EDTA (50% inhibitory concentration, 50 microM). VIM-2 conferred a resistance pattern to beta-lactams in E. coli DH10B that paralleled its in vitro hydrolytic properties, except for susceptibility to ureidopenicillins, carbapenems, and cefepime. bla(VIM-2) was located on a ca. 45-kb plasmid that in addition conferred resistance to sulfamides and that was not self-transmissible either from P. aeruginosa to E. coli or from E. coli to E. coli. bla(VIM-2) was the only gene cassette located within the variable region of a novel class 1 integron, In56, that was weakly related to the bla(VIM-1)-containing

  14. In vitro activities of cefminox against anaerobic bacteria compared with those of nine other compounds.

    Hoellman, D B; Spangler, S K; Jacobs, M R; Appelbaum, P C


    The agar dilution MIC method was used to test the activity of cefminox, a beta-lactamase-stable cephamycin, compared with those of cefoxitin, cefotetan, moxalactam, ceftizoxime, cefotiam, cefamandole, cefoperazone, clindamycin, and metronidazole against 357 anaerobes. Overall, cefminox was the most active beta-lactam, with an MIC at which 50% of isolates are inhibited (MIC50) of 1.0 microg/ml and an MIC90 of 16.0 microg/ml. Other beta-lactams were less active, with respective MIC50s and MIC90s of 2.0 and 64.0 microg/ml for cefoxitin, 2.0 and 128.0 microg/ml for cefotetan, 2.0 and 64.0 microg/ml for moxalactam, 4.0 and > 128.0 microg/ml for ceftizoxime, 16.0 and > 128.0 microg/ml for cefotiam, 8.0 and >128.0 microg/ml for cefamandole, and 4.0 and 128.0 microg/ml for cefoperazone. The clindamycin MIC50 and MIC90 were 0.5 and 8.0 microg/ml, respectively, and the metronidazole MIC50 and MIC90 were 1.0 and 4.0 microg/ml, respectively. Cefminox was especially active against Bacteroides fragilis (MIC90, 2.0 microg/ml), Bacteroides thetaiotaomicron (MIC90, 4.0 microg/ml), fusobacteria (MIC90, 1.0 microg/ml), peptostreptococci (MIC90, 2.0 microg/ml), and clostridia, including Clostridium difficile (MIC90, 2.0 microg/ml). Time-kill studies performed with six representative anaerobic species revealed that at the MIC all compounds except ceftizoxime were bactericidal (99.9% killing) against all strains after 48 h. At 24 h, only cefminox and cefoxitin at 4x the MIC and cefoperazone at 8x the MIC were bactericidal against all strains. After 12 h, at the MIC all compounds except moxalactam, ceftizoxime, cefotiam, cefamandole, clindamycin, and metronidazole gave 90% killing of all strains. After 3 h, cefminox at 2 x the MIC produced the most rapid effect, with 90% killing of all strains. PMID:9517922

  15. [Typing of extended-spectrum beta-lactamase-producing Salmonella typhimurium strains isolated in a pediatric unit].

    Mhand, R A; Soukri, A; Amarouch, H; Mdaghri, N E; Benbachir, M


    Extended-spectrum b-lactamases (ESBLs) derive mainly from TEM and SHV b-lactamases. These enzymes confer resistance to all oxyimino cephalosporins and monobactams except cephamycins and carbapems. ESBLs are often encoded by large plasmids that carry resistance determinants to multiple antibiotics and spread among the members of the Enterobacteriaceae. Since the first outbreak of Klebsiella pneumoniae expressing an extended-spectrum beta-lactamase reported in 1984, nosocomial infections due to Enterobacteriaceae species which produce ESBLs have been generally recovered from patients hospitalized in intensive care units. The most frequently isolated ESBL-producing strains belong to the genus Klebsiella, Escherichia, Enterobacter and Proteus; ESBLs are rarely associated with the genus Salmonella. The first Salmonella were detected in France in 1984 (Salmonella typhimurium), in Tunisia in 1988 (Salmonella wien) and in Argentina in 1991 (Salmonella typhimurium). In 1994, 10 isolates of Salmonella typhimurium expressing an extended-spectrum beta-lactamase were isolated for the first time from 10 children hospitalized in a pediatric unit of the hospital Ibn-Rochd, Casablanca. Previous study showed that all isolates belonged the same serotype, and biotype, and showed a resistance to oxyimino beta-lactams, gentamycin, tobramycin and trimethoprim-sulfamethoxazole but remained susceptible to tetracycline, chloramphenicol and quinolones. Oxyimino beta-lactams resistance determinant of all strains of Salmonella typhimurium was transferred by conjugation to Escherichia coli; Resistance to gentamycin and trimethoprim-sulfamethoxazole was also cotransferred. In this study, we characterized the relationship between all isolates by comparing plasmid profiles and patterns of proteins because there appear to be the more effective method for evaluating epidemiologic relationship between Salmonella species, and the protein profiles method has been used for many bacterial species. These

  16. Prevalence of antimicrobial resistance in enteric Escherichia coli from domestic pets and assessment of associated risk markers using a generalized linear mixed model.

    Leite-Martins, Liliana R; Mahú, Maria I M; Costa, Ana L; Mendes, Angelo; Lopes, Elisabete; Mendonça, Denisa M V; Niza-Ribeiro, João J R; de Matos, Augusto J F; da Costa, Paulo Martins


    -clavulanic acid, cephamycin, ciprofloxacin, streptomycin, and trimethoprim-sulfamethoxazole. In summary, pets with a record of one or more previous quinolone treatments and exhibiting coprophagic habits were at an increased risk of harboring multidrug-resistant E. coli strains in their feces compared to pets without these characteristics. AMR is a serious global problem, and assessing the risk markers for the presence of drug-resistant bacteria in pets, a very close source of resistance determinants to humans, is essential for the implementation of safe handling procedures for companion animals and for the prudent selection of antimicrobial compounds in veterinary practice. PMID:25294317

  17. 某院腹腔镜阑尾切除术患者围术期抗菌药物应用分析%Perioperative Use of Antibiotics in Patients Undergoing Laparoscopic Appendectomy in a Hospital

    李小燕; 许利敏


    OBJECTIVE:To investigate the perioperative use of prophylactic antibiotics in patients undergoing laparoscopic ap-pendectomy in a hospital before and after carrying out the special rectification activity on antibiotic use. METHODS:The utiliza-tion data of antibiotics in surgical patients undergoing laparoscopic appendectomy in a hospital before and after carrying out the rec-tification activity on antibiotic use (in 2012 vs. in 2013) were analyzed statistically. RESULTS:Perioperative use of prophylactic antibiotics was noted in 100% of the patients before and after the rectification activity. Before carrying out the rectification activity, the top 5 drugs in terms of usage frenquency were ornidazole,cefoxitin,cefotiam,cefmetazole and cefoperazone/tazobactam,with drugs used for 6.3 days on average;after carrying out the rectification activity,only 3 kinds were used,the use of cephamycins and special antibiotics were discontinued and the antibiotics were used for an average of 4.2 days. CONCLUSIONS:The periopera-tive use of prophylactic antibiotics in patients undergoing laparoscopic appendectomy is improved after carrying out special rectifica-tion activity on antibiotics.%目的:对比抗菌药物专项整治活动前后某院普外科腹腔镜阑尾切除术患者围术期预防性应用抗菌药物情况。方法:查阅该院普外科2012年(整治前)及2013年(整治后)腹腔镜阑尾切除术患者的出院病历,对各病历中抗菌药物的应用数据进行统计、分析。结果:该院整治前后患者围术期预防性抗菌药物使用率均为100%。整治前应用例次列前5位的药品分别是奥硝唑、头孢西丁、头孢替安、头孢美唑、头孢哌酮/他唑巴坦钠,平均用药时间为6.3 d;整治后共使用3个品种,头霉素及特殊级抗菌药物未再使用,抗菌药物平均用药时间为4.2 d。结论:抗菌药物整治活动后,该院普外科腹腔镜阑尾切除术患者围术期抗菌药

  18. 医院感染常见革兰阴性菌的临床分布及耐药性分析%Analysis Clinical Distrbution and Drug Resistance of Gram-negative Bacteria in Nosoconmial Infections

    胡文祥; 彭吉军; 蒋华; 周旭


    目的:以了解医院感染革兰阴性菌的临床分布及耐药特点,为临床抗菌药物的应用提供依据。方法对2010年~2012年我院常见的医院感染革兰阴性菌的临床分布及耐药性进行回顾性分析。结果在医院感染细菌前5位的革兰阴性菌为大肠埃氏菌、肺炎克雷伯氏菌、铜绿假单胞菌、鲍氏不动杆菌、奇异变形杆菌、其次是产气肠杆菌、阴沟肠杆菌、食麦芽假单胞菌。细菌均呈现多耐药趋势,临床常用的第一、二、三代头孢菌素类、单环内酰胺类、头霉素类、部分β-内酰胺酶抑制剂由于细菌产ESBLs及AmpC而发生耐药,第四代头孢吡肟耐药率也达50%~60%,耐碳青霉烯类鲍氏不动杆菌由于碳青霉烯类抗菌药物的使用强度增加而显著增加,我院美罗培南、亚胺培南耐药率逐年明显上升已接近60%。而氨基糖苷类中的阿米卡星除鲍曼氏不动杆菌外由于近期少用使敏感性有所提高。结论分析医院感染常见感染细菌分布及耐药性,对指导临床合理应用抗菌药物及预防和控制耐药菌在医院内传播有着重要意义。%Objective To investigate the clinical distribution and drug resistance of gram-negative bacteria in nosoconmial infections and to proved the reference for reasonable use of the antibiotics.Methods The clinical distribution and drug resistance of gram-negative bacteria in nosoconmial infections from 2010 to 2012 were analysis by the means of retrospective survey.Results The top ifve were Escherichia coli, Klebsiella spp, Pseudomonas aeruginosa, Acinetobacter baumanii and Proteus mirabilis. The behind three were Enterobacter aerogenes, Enterbacter cloacae, Stenotrophomonas maltophilia. The gram-negative bacteria in nosoconmial infections were multidrug resistance to antibiotics. The 1, 2, 3 generation of cephalosporin, single ring lactam, Cephamycins antibiotics and part β-lactamase inhibitor were resistance to

  19. Regeneration System and Influencing Factors of Maize in Ningxia%宁夏玉米高效再生体系的建立及其影响因素

    甘晓燕; 王劲东; 陈虞超; 李欣; 佘奎军; 李苗; 石磊; 宋玉霞


    以4个宁夏玉米品种幼胚为材料,采用组织培养法,研究培养基类型、基因型、外源激素、头孢霉素(Cef)对玉米幼胚培养及再生的影响.结果表明,在愈伤组织诱导过程中,Ⅰ号和Ⅱ号培养基诱导率较高,宁玉12号和宁0816的胚性愈伤组织诱导率相对较高,达到85.3%和82.1%;6-BA对不同基因型愈伤组织分化率的影响不同,添加6-BA对愈伤组织的分化均有促进作用;此外,当Cef质量浓度高于500 mg/L时,愈伤组织分化明显受到抑制.最佳诱导培养基为基本元素N6+水解酪蛋白200 mg/L+脯氨酸690 mg/L+2,4-D 2.0 mg/L+蔗糖30 g/L+肌醇100 mg/L+AgNO3 10 mg/L,最佳分化培养基为基本培养基N6+ 6-BA1.0 mg/L+蔗糖50 g/L.%Using immature embryo of four maize varieties in Ningxia as explants and utilizing the plant tissue culture method,the effect of medium type,genotype,exogenous hormone and cephamycin (Cef) on in vitro culture and regeneration was studied. The results showed that different medium type and genotype showed different ability of embryogenic callus inducing. I and Q had more high rate of induction, Ningyu 12 and Ning 0816 had high rate as 85. 3% and 82. 1% respectively;6-BA were the most important factor for the induction of differentiation of embryogenic callus, 6-BA could promote the differentiation of embryogenic callus. Respectively,when 500 mg/L of Cef was added,the differentiation of callus was significant inhibited. The best inducing medium was N6 + Casein hydrolysate 200 mg/L+Pro 690 mg/L+2,4-D 2. 0 mg/L + Sugar 30 g/L+Inositol 100 mg/L+AgNO310 mg/L, The best differentiation medium was: N6 + 6-BA1.O mg/L+Sugar 50 g/L.

  20. Analysis of β-lactamase phenotypes and carriage of selected β-lactamase genes among Escherichia coli strains obtained from Kenyan patients during an 18-year period

    Kiiru John


    Full Text Available Abstract Background Although β-lactam antibiotics are heavily used in many developing countries, the diversity of β-lactamase genes (bla is poorly understood. We screened for major β-lactamase phenotypes and diversity of bla genes among 912 E. coli strains isolated from clinical samples obtained between 1992 and 2010 from hospitalized and non-hospitalized patients. Results None of the isolates was resistant to carbapenems but 30% of all isolates were susceptible to cefepime, cephamycins and piperacillin-tazobactam. Narrow spectrum β-lactamase (NSBL phenotype was observed in 278 (30% isolates that contained blaTEM-1 (54% or blaSHV-1 (35% or both (11%. Extended Spectrum β-lactamase (ESBL phenotype was detected in 247 (27% isolates which carried blaCTX-M-14 (29%, blaCTX-M-15 (24%, blaCTX-M-9 (2%, blaCTX-M-8 (4%, blaCTX-M-3 (11%, blaCTX-M-1 (6%, blaSHV-5 (3%, blaSHV-12 (5%, and blaTEM-52 (16%. Complex Mutant TEM-like (CMT phenotype was detected in 220 (24% isolates which carried blaTEM-125 (29%, while blaTEM-50, blaTEM-78, blaTEM-109, blaTEM −152 and blaTEM-158 were detected in lower frequencies of between 7% and 11%. Majority of isolates producing a combination of CTX-M-15 + OXA-1 + TEM-1 exhibited resistance phenotypes barely indistinguishable from those of CMT-producers. Although 73 (8% isolates exhibited Inhibitor Resistant TEM-like (IRT phenotype, blaTEM-103 was the only true IRT-encoding gene identified in 18 (25% of strains with this phenotype while the rest produced a combination of TEM-1 + OXA-1. The pAmpCs-like phenotype was observed in 94 (10% isolates of which 77 (82% carried blaCMY-2 while 18% contained blaCMY-1. Isolates from urine accounted for 53%, 53%, 74% and 72% of strains exhibiting complex phenotypes such as IRT, ESBL, CMT or pAmpC respectively. On the contrary, 55% isolates from stool exhibited the relatively more susceptible NSBL-like phenotype. All the phenotypes, and majority of the bla genes, were

  1. 牛源耐甲氧西林金黄色葡萄球菌的检测%Detection of Methicillin-resistant Staphylococcus aureus Strains Isolated from Bovine Mastitis

    苏洋; 蒲万霞; 邓海平; 李春慧; 梁红雁; 陈智华


    本研究旨在了解甘肃地区奶牛乳房炎金黄色葡萄球菌的耐药性和耐甲氧西林金黄色葡萄球菌的感染情况,为奶牛乳房炎的防制提供理论依据.采用KB纸片扩散法,检测17株金黄色葡萄球菌对8种不同抗菌药物的敏感性;再用琼脂稀释法检测了苯唑西林、万古霉素对金黄色葡萄球菌的最小抑菌浓度(MICs);头孢西丁纸片扩散法和PCR扩增特异性mecA耐药基因对所有受试菌株进行全面的耐甲氧西林金黄色葡萄球菌检测.结果表明,菌株对青霉素、磺胺异恶唑具有较强抗性,而对环丙沙星、头孢唑啉、万古霉素和苯唑西林全敏感;头孢西丁纸片扩散法未能检测出表型为MRSA的阳性菌株,而PCR方法却检测出8株mecA基因阳性菌株,且这些菌株的苯唑西林MIC均小于2μg/mL.菌株的耐药情况较严重,对甲氧西林敏感而携带mecA基因的菌株高频存在于被调查地区的奶牛场中.%The aim of present study was to investigate the antimicrobial resistance, and the prevalence of methicillin-resistant Staphylococcus aureus (S. aureus) isolated from bovine mastitis in Gansu province, to provide credible theory evidence for prevention and treatment on bovine mastitis. Eight commonly used antimicrobial agents were used for determining antimicrobial susceptibility of 17 total S. aureus strains by disk diffusion method. Agar screen method was used for determining the oxacil-lin and vancomycin minimum inhibitory concentration value as well. Disk diffusion method using the cephamycin antibiotics ce-foxitin and detection of mecA gene by PCR assay were performed to detect the presence of MRSA. Most of strains showed a high resistance for penicillin and sulfafurazole, yet keeping complete sensitivity for ciprofloxacin, cefazolin, vancomycin and ox-acillin. None MRS A isolate was identified by the phenotypic detection method, but eight MRSA isolates with the MIC of oxac-illin lower than 2 μg/mL were

  2. Elimination of indigenous endophytic bacteria in Eucalyptus urophylla by heat and antibiotics treatment%热处理和抗生素对桉树固有内生细菌去除的研究

    宋艳祥; 王玉凤; 冉隆贤


    In order to obtain endophytic bacteria free seedlings of Eucalyptus urophylla , three methods were applied to eliminate or inhibit the indigenous endophytic bacteria in E. Urophylla, I. E. , heat treatment of the seeds of E. Urophylla at stable and variated high temperatures, heat treatment of seedlings from tissue culture of E. Urophylla combined with apical meristem culture, and antibiotics treatment of the seedlings grown in tissue culture. A differential staining procedure was used to detect the existence of endophytic bacteria and hemacytometer counting method was used to study the bacterial population. The results showed that there was no obvious effect in the elimination of endophytic bacteria by heat treatment of the seeds, and the bacteria in root of treated seedlings had a bit more population than that of control. However, the bacteria in stem and leaf of treated seedlings had less population than those of control. After the heat treatment of seedlings combined with shoot-tip culture, the endophytic bacteria can be removed effectively as the temperature increased daily, with less number compared with control. And when it reached 40 ℃ , the bacterial growth was inhibited largely. Heat treatment at 37 ℃ reduced the number of indigenous bacteria at 20th and 21st day, with a population of 5. 33 × 108 CFU/g and 4. 02 × 108 CFU/g, respectively, and only about one seventh of the number of control at 3. 43 × 109 CFU/g. When the temperature for heat treatment reached 40 ℃ , the number of bacteria decreased to 1. 63×108 CFU/g, occupied only one forty-seventh of the bacteria number of control at 7. 70 × 109CFU/g, indicating that treatment with higher temperature at 37 ℃ and 40℃ could significantly reduce the number of bacteria in seedlings grown in vitro culture. The population of the endophytic bacteria of E. Urophylla increased obviously after growing in the MS supplemented with antibiotics, I. E. , oxytetracycline, tetra-cycline and cephamycins

  3. 卫生部全国细菌耐药监测网2011年女性尿标本来源细菌耐药监测%Ministry of Health National Antimicrobial Resistance Investigation Net annual report of 2011 : bacterial resistances monitor of women urine samples

    齐慧敏; 吕媛


    Objective To summarize bacterial resistance in the women clinical urine culture samples collected in 2011 from 149 hospitals of Mohnarin. Methods Conventional culture, automatic clinical microbiological system, disk diffusion and E — test methods were used for antibacterial activity of antimicrobial agents and resistances and sensitivity were calculated by using WHONET5. 6 software. Results A total of 32682 strains of bacteria were isolated, of which of E. Coli, Enterococcus faeci-um, Enterococcus faecalis, Klebsiella pneumonia and Proteus mirabilis, respectively. The antimicrobial agents with lower antibiotic resistance rates of E. Coli were carbapenems ( 0.6%), piperacillin/tazobactam (3. 7% ) , nitrofurantoin ( 5. 3% ) , cefoperazone / sulbactam ( 5. 5% ) , amikacin (6. 0% ) ,fosfomycin (8. 7% ) .cefoxitin ( 12. 0% ) ,ticarcillin/ clavulanic acid (12. 5% ) , and amoxicillin/clavulanic acid ( 15. 5% ) , respectively. That of Enterococcus spp. Were teicoplanin(0. 4% -2. 4% ), vancomycin ( 1. 2% — 4. 6% ) , amoxicillin / clavulanic acid (1.4% — 11.3%), piperacillin/tazobactam (8. 1 - 15. 5% ) ,fosfomycin (5. 3% -20. 2% ) and nitrofurantoin (5. 9% - 49. 0% ) , respectively. No linezol id resistant Enterococcus were found. Conclusion E. Coli remains the urinary tract infection major pathogen but the proportion of Enterococci was significantly increased. The overall results of antibiotic resistance were serious. Nitrofurantoin, fosfomycin and amoxicillin / clavulanic acid can be chose as empirical treatment of oral antibiotics. Antimicrobial agents with enzyme inhibitor, cephamycin aminoglycosides and carbapenems can be chose as empirical treatment of injection antibiotics.%目的 总结我国2011年临床女性尿标本来源细菌耐药状况.方法 149家医院女性尿标本中的细菌,用自动化临床微生物测定方法、纸片法或E-test法测定细菌药物敏感性,用WHONET 5.6软件进行分析.结果 共分离细菌32682株,其中排在前5位