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Objective To investigate antimicrobial resistance among nosocomial gram-negative bacilli in 2006.Methods About 987 consecutive and non-repetitive gram-negative bacilli were isolated from 10 teaching hospitals from Sep.to Dec.in 2006 in China.All of these isolates were sent to the central laboratory for reidentification and susceptibility testing.The minimal inhibitory concentration(MICs)of meropenem and other antibacterial agents were determined by agar dilution method.Results The activity of antibacterial agents against Enterobacteriaceae was as fol lows in descending order of susceptible rate: meropenem(susceptible rate 99.8%),imipenem(99.5%),piperacillin/tazobactam(91.3%),amikacin (89.3%),cefepime(83.8%),cefoperazone/sulbactam(79.7%),ceftazidime(74.7%),cefotaxime (57.7%),ceftriaxone(56.6%),ciprofloxacin(53.6%).The prevalence of extended-spectrum β-Iactamases(ESBL)was 59.0% in Escherichia coli,33.0%in Klebsiella pneumoniae and 8.0%in Proteus mirabilis.The most active agents against E.coli and K.pneumoniae were meropenem,imipenem(99.2%. 100%),piperacillin/tazobactam(90.8%-97.0%),and amikacin(83.8%-92.4%).Cefepime Was more active against K.pneumoniae than E.coli(85.4% vs.65.2%).Against E.cloacae,E.aerogenes and Citrobacter freundii,the most active agents were as follows in desecnding order:meropenem,imipenem (99.2%-100%),amikacin(85.2%-92.6%),cefepime(81.5%-85.9%),piperacillin/tazobactam (73.4%-87.2%),cefoperazone/sutbactam(65.6%-77.7%),and ciprofloxacin(53.1%-72.3%).The most active agents against Pseudomonas aeruginosa were amikacin(83.5%),followed by meropenem (79.1%),piperacillin/tazobactam(74.1%),and imipenem(70.9%).The most susceptible agents against Acinetobacter baumannii were imipenem(79.1%),meropenem(73.4%) and cefoperazone/ sulbaetam(54.7%).Mutiresistant A.baumannii increased up to 53.0%.The most active agents against Burkholderia cepacia were meropenem(73.3%),eeflazidime(73.3%),and piperacillin/tazobactam (62.2%).Conclusions Carbapenems remained very high activity against Enterobacteriaceae.Increasing resistance to 10 antimicrobials agents tested from A.baumanni and P.aeruginosa brought great concern.
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80% activity rate against E.coli included piperacillin/tazobactam(93.4%)、ceftazidime(86%),and amikacin(83.3%);The susceptible rate to piperacillin/tazobactam in K.pneumoniae was 84.6%. The susceptible rate to ceftazidime decreased from 82.3% to 69.9%, which was lower than to cefepime (77.2%). Over 50% of Enterobacter cloacae were resistant to ceftazidime, cefotaxime and ceftriaxone. Susceptible rates to piperacillin/tazobactam in E. cloacae,E. aerogenes,Citrobacter freundii and Serratia marcescens (67.7%-96.4%) were higher than those to cefepime (68.8%-77.5%), cefoperazone/sulbactam (59.7%-87.5%). Susceptibility to amikacin among these 4 species (70%-83.7%) was higher than to ciprofloxacin (48.1%-79.5%). All of Morganella morganii and Proteus vulgaris isolates were susceptible to meropenem and imipenem; Over 90% of the isolates were susceptible to cefepime, cefoperazone/sulbactam and piperacillin/tazobactam.The most active agent against Pseudomonas aeruginosa was meropenem (84%), followed by amikacin, piperacillin/tazobactam, ceftazidime and imipenem (72.5%-76.6%). Mutiple-drug-resistant Acinetobacter baumannii increased from 33% in 2003 to 48% in 2004. Resistance to carbapenems increased to 18% in this species in 2004. The most active agents against Burkholderia cepacia were meropenme (64.9%), cefoperazon/sulbactam (63.2%), ceftazidime (59.6%), piperacillin/tazobactam (56.1%) and cefepime (52.6%).Conclusions Carbapenems remained very high activity against Enterobacteriaceae. Increasing resistance to 10 antimicrobials agents tested among A. baumanni brought great concern. Meropenem was 4-to 16-fold more active against common gram-negative bacilli than imipenem.
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Objects To observe the TEM gene characteristic of Acinetinbacter lwoffi strains which were resistant to most kind of antibiotics and to compare their sequences with that of Escherichia coli Methods Two strains of A lwoffi, JN18 and JN70,were isolated from sputum of patients′ who suffered from respiratory infection TEM, SHV, OXA, IMP and CTX M genes were tested by PCR TEM sequences of JN18 and JN70 were detected by ABI automated sequencer and were analysed by DNAStar software to compare the differences with E coli TEM genes that had been published in GenBank Results Detected sequences of A lwoffi JN18 and JN70 strains were 1012 bp and 887 bp, respectively They coded regions of 832 bp and 772 bp for TEM of the two strains that were 98 2% identical In other hand, there were 14 pair bases differently in TEM regions The TEM sequence of JN18 was 98 72% identical to that of E coli TEM on the average, which was over 99% to TEM1D, TEM 70, TEM 76, TEM 77 and TEM 95 of E coli The divergence of TEM genes was 1 26 between A lwoffi JN18 strains and E coli JN70 strain had higher identity (98 93%), which reached 99 5% to TEM1D, TEM1F and TEM84 of E coli As JN18 strain, TEM gene of JN70 had very small divergence (1 06 ) with E coli Conclusion JN18 and JN70 strains of A lwoffi isolated from patients′respiratory tract in Jinan shared most of sequences with E coli TEM76 and 84 However, there were many mutant sites in them
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Objective To detect ESBLs in E.coli and K.pneumoniae with appropriate method.Methods The suspiciously produced ESBLs were detected by standard screen test among 110 E.coli and 84 K.pneumoniae. ESBLs possessing strains were confirmed by E test, single disc diffusion test with clavulanic acid or sulbatan, and two kinds of double disc synergy test. Results There was a significant difference between the detected rate of ESBLs in E.coli (16/26) and K. pneumoniae (4/20) by E test( P 0.05). The single disc diffusion test with clavulanic acid or sulbatan was applicable to confirm ESBLs in K. pneumoniae (12/20). Conclusions Single disc diffusion test is a sensitive, convenient and inexpensive method to confirm ESBLs in E.coli and K.pneumoniae in clinical laboratory.