Antibiotic susceptibility profiles of Gram-negative bacterial uropathogens in a tertiary hospital, southwest Nigeria

Background: Increasing rates of antibiotic resistance have made it necessary to regularly monitor antibiotic susceptibility patterns of gram negative bacterial uropathogens in order to optimize antibiotic therapy for urinary tract infections. The aim of this study was to analyze the antibiotic susceptibility patterns of Gram-negative bacterial uropathogens in Babcock University Teaching Hospital, Ilishan-Remo, southwest Nigeria. Methodology: This study was a retrospective review of the Medical Microbiology Laboratory records of the hospital to analyze the in vitro antibiotic susceptibility patterns of Gram-negative urinary bacterial isolates between May 2016 and April 2022. The bacteria were isolated and identified from routine urine samples using standard bacteriological methods. In vitro antibiotic susceptibility test (AST) to amoxicillin-clavulanate, piperacillin-tazobactam, ceftriaxone, ceftazidime, nitrofurantoin, ciprofloxacin and meropenem was routinely performed by the modified Kirby-Bauer disk diffusion test and susceptibility break points determined using the Clinical and Laboratory Standards Institute (CLSI) guidelines. Results: A total number of 3,549 urine samples were processed during the period of review, and 808 (22.8%) samples yielded positive bacterial cultures. Of the 808 isolates, 604 (74.8%) were Gram-negative bacteria. The most frequently isolated Gram-negative bacteria were Escherichia coli (41.9 %) and Klebsiella spp (27.5%) while Pseudomonas spp and Proteus spp accounted for 4.3% and 1.0% of all isolates respectively. Meropenem had the highest in vitro antibacterial activity (74.3% to 90.3% of isolates were sensitive) for all isolates. Overall, E. coli, Klebsiella spp., and Proteus spp. showed high resistance rates to amoxicillin-clavulanate (65.3% to 97.1%). Conclusion: Effective antimicrobial stewardship programs must be in place in order to ensure the appropriate use of antibiotics for treating urinary tract infections.