Prevalence of extended-spectrum beta-lactamases among Enterobacteriaceae isolated from blood culture in a tertiary care hospital.

OBJECTIVE: To determine the prevalence of extended spectrum beta-lactamase among Enterobacteriaceae isolated from blood culture in a tertiary care hospital. METHODS: We carried out this study at the Armed Forces Hospital, Riyadh, Kingdom of Saudi Arabia during the period between January 2003-December 2004. We tested a total of 601 isolates of the family Enterobacteriaceae from blood culture for the prevalence of extended spectrum beta-lactamase (ESBL) production by the standardized disc diffusion method and confirmed by the ESBL E test strips. RESULTS: Ninety-five (15.8%) of the isolates were ESBL producers. Among these, 48.4% were Klebsiella pneumoniae (K. pneumoniae) followed by 15.8% of both Escherichia coli (E. coli) and Enterobacter cloacae (Ent. cloacae). Other isolates produced ESBL in low numbers. CONCLUSION: Klebsiella pneumoniae produced ESBL in significant numbers. Extended spectrum beta-lactamase gram-negative bacilli present significant diagnostic and therapeutic challenges to the management of infections due to these organisms. Microbiology laboratories should start reporting ESBL producing Enterobacteriaceae organism due to their importance in respect to antibiotic therapy and infection control aspects.