Prevalence and Antibiotic Resistance Profiling of Escherichia coli in Seafood and Coastal Waters of Malokun Sea, Ilaje, Ondo State, Nigeria

Abstract

Background: This study investigates the prevalence, and antibiotic resistance profiles of Escherichia coli isolated from fish, shrimps, crab, and water collected from the Malokun Sea, Ilaje, Ondo State, Nigeria. The aim was to assess contamination levels and antibiotic resistance patterns to inform microbial risk assessments and public health interventions. Methodology: Standard microbiological and molecular techniques were employed for the isolation and identification of E. coli using Most Probable Number (MPN) assays and Polymerase Chain Reaction (PCR). Antibiotic susceptibility was tested against eight commonly used antibiotics using the Kirby-Bauer disc diffusion method and interpreted according to standard CLSI guidelines. Results: A total of 37 confirmed E. coli isolates were evaluated: Comparative analysis revealed higher E. coli loads for MPN-PCR (3.00 ± 0.89 log CFU/mL) indicating enhanced detection of viable but non-culturable cells. In contrast, MPN/EMB detected significantly higher bacterial loads in shrimps (4.46 ± 0.22 log CFU/g) and fish (3.36 ± 0.31 log CFU/g) compared to PCR. Crab samples showed relatively low E. coli levels, with minimal difference between methods. All isolates exhibited 100% resistance to penicillin, ceftazidime, and doripenem, but fully susceptible to amikacin and norfloxacin. Multiple Antibiotic Resistance (MAR) indices ranged from 0.375 to 0.625, with the resistance pattern CAZ-DOR-P consistently observed across all sample types. Conclusion: The presence of multidrug-resistant E. coli in seafood and water from the Malokun Sea presents a significant public health concern. These preliminary findings underscore the need for integrated culture-based and molecular surveillance alongside improved seafood hygiene and stricter antibiotics regulation, to mitigate the transmission of resistant pathogens in aquatic environments and through aquatic food chain.