Prevalence and antimicrobial susceptibility patterns of bacteria colonizing the external ocular surfaces of patients undergoing ocular surgeries at Bugando Medical Center in Mwanza, Tanzania

Abstract

<title>Abstract</title> <bold>Objective</bold> Understanding microbiota colonizing ocular surfaces is key to expedite antibiotic prophylactic options for ocular surgeries, and therefore, prevent subsequent surgical site infections (SSIs). To fill this critical gap, we aimed at determining the prevalence and antibiotic susceptibility patterns of bacteria colonizing the external ocular surfaces of 224 patients undergoing ocular surgeries at Bugando Medical Centre (BMC) in Mwanza, Tanzania between May and August 2023. <bold>Results</bold> The study participants had a median age of 62.5 (interquartile range: 39.5-75.0) years. A total of 78.1% (175/224) ocular swabs were culture positive yielding 196 bacterial isolates. <italic>S. epidermidis </italic>[43.4% (n=85)] followed by <italic>S. aureus </italic>[21.9% (n=43)] and <italic>Pseudomonas aeruginosa </italic>[14.3% (n=28)] were the most common bacteria. There was low proportions of resistance among predominant Gram positive and Gram-negative bacteria to gentamicin (≤25.0%), and similarly, low resistance among Gram negative bacteria was observed against 3^rd generation cephalosporins (≤25.0%) and piperacillin-tazobactam (0.0%). Variable resistance profiles were notable to the most commonly used antibiotics (ciprofloxacin and tetracycline: 0.0% to 66.7%). Our findings underscore an urgent need to revisit antibiotic prophylactic guidelines for ocular surgeries in this tertiary hospital, and calls for prospective evaluation of incident SSIs post-ocular surgeries to guide specific management.