Culture and Kirby-Bauer disk diffusion analysis of the prevalence andantibiotic susceptibility patterns of common urinary pathogens in acommunity-based study in Owerri, Nigeria

ABSTRACT:

Urinary tract infections (UTIs) represent one of the most common bacterial infections globally, affecting approximately 150 million people annually. In Nigeria, empirical antibiotic therapy for UTIs is often guided by outdated or non-local resistance data, contributing to the growing challenge of antimicrobial resistance. This study aimed to determine the etiologic spectrum of community-acquired urinary tract infections and establish local antibiotic susceptibility profiles in Owerri, Nigeria. A prospective laboratory-based study was conducted from January to December 2024. Clean-catch mid-stream urine samples were collected from 512 patients presenting with symptoms of UTI at primary healthcare centers in Owerri. Samples were processed using conventional culture techniques on cysteine lactose electrolyte deficient (CLED) and MacConkey agars. Significant bacteriuria was defined as ≥10⁵ CFU/mL. Bacterial isolates were identified by standard biochemical tests, and antibiotic susceptibility testing was performed using Kirby-Bauer disk diffusion method against commonly prescribed antibiotics. Of the 512 samples processed, 186 (36.3%) showed significant bacteriuria. The most prevalent uropathogen was Escherichia coli (48.9%), followed by Klebsiella pneumoniae (16.7%), Staphylococcus saprophyticus (11.3%), Proteus mirabilis (8.6%), and Enterococcus faecalis (7.5%). High resistance rates were observed for amoxicillin-clavulanate (68.2%) and cotrimoxazole (62.9%). Moderate resistance was noted for ciprofloxacin (44.1%), while nitrofurantoin maintained good efficacy (84.4% susceptibility). Female patients, particularly those aged 25-44 years, showed higher prevalence of UTIs. The high resistance rates to commonly prescribed antibiotics underscore the necessity for regular local antimicrobial resistance surveillance and ongoing antibiotic stewardship programs in Owerri, Nigeria. Nitrofurantoin remains a viable option for empirical treatment of uncomplicated UTIs in this region, while amoxicillin-clavulanate and cotrimoxazole should be used with caution.

Keywords: Urinary tract infections, antimicrobial resistance, Nigeria, Kirby-Bauer, Empirical therapy, Uropathogens.