RESUMEN
BACKGROUND: Extended-spectrum beta-lactamases(ESBL) are enzymes that confer resistance to oxyimino-beta-lactams as well as to penicillins and cephalosporins. Strains of Klebsiella pneumoniae and Escherichia coli that produce ESBL have been increasingly prevalent in many countries. The purpose of this study was to investigate the ESBL production rate of K. pneumoniae and E. coli at the in Yeungnam University Medical Center. MATERIALS AND METHODS: Thirty-one isolates of K. pneumoniae and twenty-five isolates of E. coli were examined for ESBL by double disk synergy test, using 20/10microgram ticarcillin/clavulanic acid and 30microgram oxymino-beta-lactam(ceftazidime, ceftriaxone and aztreonam) disks. RESULTS: Fifty-two percent of K. pneumoniae and sixteen percent of E. coli isolates revealed double disk synersism. Majority of ESBL-producing strains(fifty-five percent) were isolated from patients in the intensive care unit. CONCLUSION: ESBL production of K. pneumoniae and E. coli were also common at the Yeungnam Univercity Medical Center and pose a serious problem for antimicrobial therapy.