Bacteriuria by extended-spectrum Beta-lactamase-producing Escherichia coli and Klebsiella pneumoniae: isolates in a governmental hospital in South of Tehran, Iran.

INTRODUCTION: Antibiotic resistant mutants producing extended-spectrum beta-lactamase (ESBL) have emerged among Escherichia coli and Klebsiella pneumoniae. This study was done to determine the frequency of ESBL-producing E coli and K pneumoniae species isolated from urine samples of our patients.

MATERIALS AND METHODS: A study was conducted on 164 urine isolates (124 E coli and 40 K pneumoniae) in the laboratory Loghman Hakim Hospital in Tehran, Iran, in 2007. Microbial sensitivity tests were done on Mueller-Hinton agar plates with disk diffusion method. Broad-spectrum resistance was defined as resistance to ampicillin or cephalothin; ESBL resistance, as resistance of these bacteria to one of ceftriaxone, ceftazidime, or ceftizoxime; and MDR-ESBL; as resistance to 3 of the following antibiotic groups: trimethoprim-sulfamethoxazole, aminoglycosides, fluoroquinolones, and nitrofurantoin.

RESULTS: An ESBL resistance was detected in 52.5% of isolates with K pneumoniae and 45.2% of those with E coli. The MDR-ESBL pattern was detected in 26.8% of the isolates. These included 30.0% of the K pneumoniae and 25.8% of the E coli isolates. Broad-spectrum resistance was detected in all K pneumoniae isolates and 87.9% of 124 E coli isolates.

CONCLUSIONS: Our study showed a high rate of ESBL resistant strain of E coli and K pneumoniae and the emergency of multiple drug resistance to these bacteria in our patients in Tehran, Iran.