"Molecular Characterization and Antimicrobial Susceptibility of E. coli O157:H7 Strain Across Dairy Animals, Humans and Farm Environmental Interface in Selected Sub-Cities of Addis Ababa
No Thumbnail Available
Date
2025
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
Addis Abeba University
Abstract
Escherichia coli O157:H7 is a zoonotic pathogen of major public health concern due to its high virulence, ability to survive in the environment, and increasing resistance to antibiotics. This study adopted a One Health approach to investigate the prevalence, molecular characterization, and antimicrobial susceptibility patterns of E. coli O157:H7 isolated from dairy animals, humans, and farm environment in Addis Ababa, Ethiopia. A cross-sectional study was conducted between November 2024 and April 2025 across 60 dairy farms, with 470 samples samples collected from raw milk, human hand swabs, water, and manure (from both bedding and waste areas). A structured questionnaire was administered to 60 farms to identify potential risk factors. Isolation and identification was
done using selective culture media and biochemical tests, while confirmation of the E. coli O157:H7 serotype was done via PCR. Antimicrobial susceptibility was determined using the Kirby-Bauer disk diffusion method, and data were analyzed using Descriptive statistics and chi-square.Out of 470 total samples, 32.7% (154/470) tested positive for E. coli, and 0.6% (3/470) were confirmed as E. coli O157:H7. Based on analysis, sample types had a significant effect on the occurrence of E. coli and E. coli O157:H7. The prevalence of E. coli O157:H7 was 1.7% in both manure and hand swabs, and 0.4% in milk samples. Overall E. coli detection was significantly highest in waste-area manure (66.7%) compared to bedding manure (56.7%), hand swabs (53.3%), water (23.3%), and milk (14.8%) (p < 0.05). All E. coli O157:H7 isolates exhibited resistance to ampicillin(100%) and tetracycline (90%), while high susceptibility was observed for norfloxacin (90%), cefotaxime (85%), and cefoxitin (85%). Multidrug resistance was observed in isolates showing resistance to at least three antibiotics. The questionnaire survey revealed that lack of handwashing before milking, absence of disinfectant use, and poor farm hygiene were significantly associated with E. coli O157:H7 presence (p < 0.05).The findings highlight the importance of promoting rational antibiotic use and improving hygienic practices at the
farm level to reduce the growth of drug-resistant E. coli O157:H7.
Description
Keywords
Addis Ababa, Antimicrobial Susceptibility Test, Dairy Farms, E. coli O157:H7, OneHealth, Prevalence.