Antimicrobial resistance in Escherichia coli strains from urinary tract infections.

An increase in resistance against many different drugs among urinary tract infection (UTI) E coli isolates has been observed in the last 2 decades. This study determined the trends of antimicrobial resistance in E coli to commonly used antibiotics. The study was conducted in Ile-Ife, southwest Nigeria. Patients with features suggestive of UTI were investigated for presence of significant bacteriuria. Urine isolates were identified. Antimicrobial susceptibility was evaluated in accordance with standard bacteriological methods. Of 442 urine specimens, 158 (35.8%) yielded significant growth, including 41 (25.6%) with E coli. Among the E coil isolates, antimicrobial susceptibility varied in prevalence by agent in descending order as follows: nitrofurantoin (80%), ofloxacin (24%), ciprofloxacin (15%), nalidixic acid (10%), cotrimoxazole (5%), and amoxicillin/clavulanic acid (2%). No isolate was susceptible to amoxicillin, gentamicin, or tetracycline. All were also found to be resistant to at least 3 commonly used drugs. All 25 isolates tested for extended-spectrum beta-lactamase (ESBC) production were found to be presumptive ESBCs producers. The results demonstrate the continued susceptibility of E coil to nitrofurantoin and their widespread and increasing resistance to amoxicillin, gentamicin, cotrimoxazole, ciprofloxacin, ofloxacin, and tetracycline. Nitrofurantoin is a--and, in this locale, perhaps the only--rational drug for empiric treatment of uncomplicated UTI. There is a need for a comprehensive study of the involvement of ESBC-producing E coli in UTI in this environment.