Antibiotic Susceptibility and Multidrug Resistant Patterns of Bacteria Isolated from Spoiled Food Samples

Abstract

Spoiled foods can harbour bacteria that reduce food quality and may contribute to the spread of antibiotic-resistant organisms in food-associated environments. This study isolated and characterised bacteria from spoiled meat, egg and milk samples collected around Ladoke Akintola University of Technology, Ogbomoso, Oyo State, Nigeria, and assessed their antibiotic susceptibility and multidrug-resistant patterns. The samples were processed using standard microbiological methods, while bacterial isolates were characterised through microscopy, biochemical tests and 16S rRNA-based molecular identification. Antibiotic susceptibility was evaluated using the Kirby-Bauer disc diffusion method, and the multiple antibiotic resistance index was calculated for each isolate. Eight bacterial isolates were identified: Pseudomonas sp. 1, Acinetobacter baumannii, Klebsiella sp., Acinetobacter guillouiae, Pseudomonas sp. 2, Citrobacter koseri, Salmonella enterica and Parasphingorhabdus flavimaris. The isolates showed high resistance to the tested antibiotics, with 100% resistance recorded for ceftazidime, cefuroxime, amoxicillin/clavulanate, nitrofurantoin, ampicillin, ceftriaxone, erythromycin and cloxacillin. Resistance to gentamicin, ciprofloxacin and ofloxacin was 50%, 75% and 50%, respectively. The multiple antibiotic resistance index ranged from 0.7 to 1.0, and all isolates were resistant to at least eight antibiotics. These findings indicate that spoiled foods in the study area may contain bacteria with substantial antibiotic resistance profiles, supporting the need for improved hygiene, appropriate storage and routine monitoring of resistant organisms in food environments.