Detection Of Extended-spectrum Beta-lactamases And Drug Sensitivity Test In Clinical Isolates Of The Family Enterobacteriaceae In Shanhai

[Objectives] To investigate extended-spectrum beta- lactamases(ESBLs) production in clinical isolates of the family Enterobacteriaceae in Shanghai and the resistant rates of ESBLs- producing strains to antibiotics; To evaluate the isolating rates of ESBLs by double-disk synergy test, Etest and inhibitor-potentiated disk-diffusion test respectively. [Methods] 1026 clinical isolates of the family Enterobacteriaceae were collected from 4 hospitals in Shanghai from March 1999 to October 1999. Kirby-Bauer method was used to judge drug sensitivity; Double-disk synergy test was used to detect ESBLs. Double-disk synergy test, Etest and inhibitor-potentiated disk- diffusion test were used to detect ESBLs in 10 reference strains and 200 clinical isolates of Klebsiella pneumoniae and Escherichia coli respectively. [Resultu] In 11 antibiotics, Imipenem and Cefmetazole had the lowest resistant rates of 0.10% and 13.84% respectively, while Ciprofloxacin and Cefuroxime had the highest resistant rates of 47.56% and 43.96% respectively, and the resistant rate of Escherichia coli strains to Ciprofloxacin was 68.88%; Except Ceflazidime, the resistant rates of oxyimino-lactams and monobactatns were more than 30%, which was higher than that of Amikacin(32.26%). In the boly Enterobacrtceae, the resistance of Enterobacter clOacaewas especially serious, and only the sensforities of boenem andWacin were good, with the sensitive rates being l00% and 70.9l%respectively In all l026 clforcal isolates of the familyEnterobacteriaceae, 352 stheins were considered ESBLs producers bydouble-disk synergy test, with the isolatin rate being 34.3l%.37.40%, 30.2l% and 41.82% of strains of Klebsiella pneumonltre,Eschwtia coll and Enterobacter cloacae resPectlyely wereconsiderd ESBLs producers. ESBLs was also detected in strains ofEnterObacter aerWes and Cbobacter hedi. There was noevident difference in the isolating rates betWeen differen clforcalsPecAnens, so was With difor antibiOtic disks. ExcePt bomand Cefinerezole, the resishat rates of ESBLs-producing strains toother 9 antibiotics were much higher than that of non-ESBLs-produCing strains(P < 0.0l). The resistan rates of twenem andCebole to ESBLs-producing triins were the loweSt. In l0reference strains, 9, 9 and l0 shas were considered ESBLs-producing strains by double-disk Synergy tCst, Etest, inhiitOrpotentiated disk-ditheion test resPectively In 200 clforcal isolates ofKlebsiella pneumoniae and EscheriChia coli, 73%, 75% and 79%were considered ESBLs producers with the three methodsrespechvely which were not differen evidentlyIConclusionsl The PrCvalence of ESBLs in clinical isolates ofthe boly EnterObacrtceae in Shanghai was high, and it isnecessary for clforcal laboratory to deect ESBLs in clforcal isolates ofthe family Enterobacteriaceae in routine. The resistan rates ofESBLs-producing strains to most antibiotics were much higher thantha of non-ESBLs-producing strains. Iwienem and CeAnetazolewere the effective anibiotics tO infections caused by ESBLs-producing stheins. Double-disk synergy test and inhibitorTotentiateddisk-diffosion test are sutable for screening ndins producing ESBLsin rouine in all hospitals.