High prevalence of extended spectrum beta-lactamase production among Klebsiella pneumoniae strains isolated at a university hospital in Turkey

beta-lactam susceptibility and beta-lactamase patterns of a random sample o f 44 Klebsiella pneumoniae strains that had been isolated from nosocomial i nfections at Dokuz Eylul University Hospital in Izmir, were investigated. A ll strains were amoxycillin resistant but in the presence of clavulanic aci d 26 became sensitive. Similarly 39 of the strains were resistant to ceftaz idime and cefotaxime; clavulanic acid restored sensitivity to ceftazidime i n 28 and to cefotaxime in 25 of these resistant strains. Extended spectrum beta-lactamase (ESBL) production was positive in 84% of the isolates as det ermined by the double disk synergy test. Isoelectric focusing revealed that each strain produced one to four p-lactamases, pi 7.6 enzymes being the mo st prevalent. Other enzymes with pIs of 8.4, 8.2, 5.4, 7.8 were also detect ed. Resistance to ceftazidime was transferred from 18 of the 44 isolates to the recipient Escherichia coli K-12 at 37 degrees C, The transconjugants w ere examined for their plasmid content and the plasmids were characterized by their size and resistance profile. Fourteen different restriction patter n groups were identified with Eco R1, The results indicate a high prevalenc e of ESBL production in nosocomial K pneumoniae isolates in Izmir and have major implications concerning the clinical use of later generation cephalos porins.