Empirical Analysis of Antibiotic Resistance Patterns in Urinary Tract Infections among Outpatients in Tertiary Hospitals in South West Nigeria

Background: Urinary tract infections (UTIs) are among the most common bacterial infections globally, and the emergence of multidrug-resistant uropathogens threatens standard treatment regimens. Empirical data on resistance patterns in specific Nigerian geographic zones are critical for guiding local antibiogram-based therapy. This study empirically analysed antibiotic resistance patterns in UTI-causing organisms among outpatients at tertiary hospitals in South West Nigeria. Methods: A prospective microbiological study was conducted at two teaching hospitals in Lagos and Ibadan. Mid-stream urine samples from 440 outpatients with symptomatic UTI were cultured. Identified organisms were subjected to disk diffusion sensitivity testing against a panel of fourteen antibiotics using CLSI criteria. Multidrug resistance (MDR) was defined as resistance to at least three antibiotic classes. Results: Escherichia coli (43%) and Klebsiella pneumoniae (22%) were the predominant pathogens. MDR was detected in 61 percent of isolates. Resistance to cotrimoxazole, ampicillin, and fluoroquinolones exceeded 70 percent. Nitrofurantoin and imipenem retained the highest sensitivity rates (84% and 96% respectively). Extended-spectrum beta-lactamase production was confirmed in 34 percent of Enterobacteriaceae isolates. Conclusion: UTI pathogens in South West Nigeria tertiary centres exhibit high MDR rates, necessitating empirical treatment based on local antibiograms. Nitrofurantoin represents a viable first-line option for uncomplicated UTI in this context. Keywords: antibiotic resistance, urinary tract infection, multidrug resistance, South West Nigeria, antibiogram