High‐level resistance to penicillin–streptomycin in equine wound infections in Nigeria: A 2‐year surveillance study

Summary Background Equine wounds present major challenges in veterinary care because of bacterial infections and biofilm formation. Objective The study aimed to evaluate the effectiveness of penicillin and streptomycin as initial treatments for equine wound infections through a 2‐year surveillance study conducted in Ibadan, Nigeria, from May 2023 to May 2025. Study Design A 2‐year prospective observational study. Methods Ninety wound samples from four sources were cultured using standard microbiological methods. Bacterial isolates were identified by Gram staining, biochemical tests and API 20E kits. The Kirby‐Bauer disc diffusion method was used for antimicrobial susceptibility testing. Results A total of 100 isolates were found, with Staphylococcus spp. being the most common at 46%. All 100 isolates (100%) showed complete resistance to penicillin and streptomycin. Ciprofloxacin was the most effective alternative, with 80.0% susceptibility, followed by ofloxacin at 56.0%. High resistance was noted for cefuroxime (88.0%), levofloxacin (84.0.0%) and ertapenem (84.0%). Analysis over time showed sustained 100% resistance to penicillin and streptomycin throughout the study period. Main Limitations Molecular resistance gene analysis or biofilm detection tests were not done. Conclusion The traditional use of penicillin and streptomycin as empirical therapy is ineffective for equine wound infections due to widespread antibiotic resistance. Bacterial culture and susceptibility testing should guide treatment decisions to ensure appropriate care and reduce unnecessary antibiotic use. Although ciprofloxacin had the highest susceptibility, quinolones should not be recommended as first‐choice therapy without laboratory susceptibility data or evidence of failure of other antimicrobials. Future studies should investigate resistance mechanisms and biofilm detection in equine wounds.