Surveillance of antibiotic resistance in clinical isolates from First Affiliated Hospital of Zhejiang University Medical College in 2009

Objective To investigate the resistance of clinical isolates from our hospital in 2009.MethodsAntimicrobial susceptibility testing was carried out by means of Kirby-Bauer(KB) method.The data were analyzed by WHONET 5.4 software.ResultsOf the 5 961 clinical isolates,gram-negative bacilli and gram-positive cocci accounted for 70.2%(4 185/5 961) and 29.8%(1 776/5 961),respectively.The prevalence of methicillin-resistant isolates was 49.4%(134/271) in Staphylococcus aureus(MRSA) and 69.7%(568/815) in coagulase negative Staphylococcus(MRCNS).No vancomycin or teicoplanin resistant isolate was found in Staphylococcus.One Enterococcus faecalis and 17 Enterococcus faecium isolates were found resistant to vancomycin.Majority strains(97.4%) of Streptococcus pneumoniae were susceptible to penicillin.No resistant isolate was found.Beta-hemolytic Streptococcus was highly sensitive to vancomycin,penicillin,cefotaxime,cefuroxime,and ceftriaxone.The prevalence of extended-spectrum β-lactamases(ESBLs) was 56.8%(536/944) in Escherichia coli,and 39.6%(226/570) in Klebsiella pneumoniae.Imipenem and meropenem were the most potent antimicrobial agents against Enterobacteriaceae(96%).Acinetobacter baumannii was highly resistant.Cefoperazone-sulbactam was relatively active against A.baumannii isolates(43.8% resistant).More than 70% of these isolates were resistant to imipenem and meropenem.The most active agent against P.aeruginosa was amikacin(11.5% resistant),followed by cefepime,gentamicin,ciprofloxacin,cefoperazone-sulbactam,ceftazidime,cefoperazone(16.2%-26.5% resistant).About 34.4% and 39% of these P.aeruginosa isolates were resistant to meropenem and imipenem.Minocycline was the most active agent against Stenotrophomonas maltophilia and Burkholderia cepacia(10% resistant).ConclusionsMost clinical isolates collected in 2009 were gram-negative bacilli.The antimicrobial resistance of common pathogenic bacteria was serious,especially the increasing prevalence of vancomycin-resistant Enterococcus and carbapenems-resistant Klebsiella pneumoniae.