Antimicrobial Resistance Profiles of Uropathogens and the Chemical Basis of Resistance Among Isolates from Teaching Hospitals in Anambra State

Urinary tract infections caused by resistant uropathogens present an escalating clinical challenge across Nigerian tertiary hospitals. The molecular and chemical mechanisms underpinning resistance, particularly beta-lactamase production and efflux pump upregulation, remain undercharacterised in the South East geopolitical zone. This study profiled antimicrobial resistance patterns and investigated the chemical basis of resistance in uropathogens isolated from patients at Nnamdi Azikiwe University Teaching Hospital and Chukwuemeka Odumegwu Ojukwu University Teaching Hospital in Anambra State. A total of 284 non-duplicate clinical urine isolates were collected over eighteen months. Species identification and antimicrobial susceptibility testing were performed using the Kirby-Bauer disc diffusion method interpreted by CLSI breakpoints. Extended-spectrum beta-lactamase production was screened phenotypically and confirmed by the double-disc synergy test. Efflux pump activity was assessed using carbonyl cyanide m-chlorophenylhydrazone inhibition assays. ESBL prevalence was 48% among Klebsiella pneumoniae isolates and 37% among Escherichia coli. Efflux pump contribution to fluoroquinolone resistance was confirmed in 62% of resistant P. aeruginosa isolates. Carbapenem resistance was detected in 8% of Klebsiella isolates. Multi-drug resistance was associated with prior antibiotic use and recurrent infection history. These findings indicate a high burden of chemically complex resistance mechanisms among uropathogens in Anambra State, with significant implications for empirical treatment guideline revisions and the urgent need for stewardship interventions. Keywords: antimicrobial resistance, uropathogens, ESBL, efflux pump, Anambra State.