Assessment of Antibiotic-Resistant E. coli in Cowshed Environments in Owo, Nigeria: Implications for Public Health

Abstract

This study assessed the microbial load, and antibiotic resistance profiles of Escherichia coli (E. coli) isolated from cowshed soil and wastewater in Owo metropolis, Nigeria. The total microbial count ranged from 2.73 × 10⁴ to 1.66 × 10⁸ cfu/mL, with an average of 2.41 × 10⁷ cfu/mL, indicating significant bacterial contamination. All isolates were Gram-negative, oxidase-negative, and predominantly indole- and citrate-positive. PCR amplification targeting the uidA gene confirmed the identity of E. coli in 16 of 25 phenotypically suspected isolates, reinforcing the reliability of molecular diagnostics. Antibiotic susceptibility testing revealed that all isolates exhibited 100% resistance to penicillin, doripenem, and amikacin. High resistance was also recorded for ceftazidime (89%) and cefepime (78%), while norfloxacin showed the highest susceptibility (89%). Wastewater isolates demonstrated slightly higher resistance levels, with 100% resistance to ceftazidime and MARI values ranging from 0.5 to 0.875, compared to soil isolates with MARI values between 0.375 and 0.75. These findings suggest that cowshed environments serve as reservoirs for multidrug-resistant E. coli, likely due to the indiscriminate use of antibiotics in livestock and inadequate waste disposal practices. The presence of resistant E. coli in environmental matrices poses a serious public health threat, particularly in communities using nearby water sources for domestic purposes and underscores the urgent need for stricter regulation of antimicrobial use in animal farming, and continuous environmental surveillance to curb the spread of antibiotic resistance and protect both human and environmental health.