Comparative Analysis of Antimicrobial Resistance Patterns in Staphylococcus Aureus and Escherichia Coli Across the one Health Interface

Abstract

The livestock sector is a key contributor to Pakistan’s economy, accounting for 14.36% of GDP and supporting rural livelihoods. This study investigated the prevalence and antimicrobial resistance profiles of Staphylococcus aureus and Escherichia coli from animal, human, and environmental sources in District Bahawalpur. A total of 420 samples were collected, including sheep (n=100), goat (n=100), environmental samples (n=120), and livestock handlers (n=100). Isolation and identification were performed using standard microbiological techniques, followed by biochemical confirmation. Antimicrobial susceptibility testing was conducted using the disk diffusion method. The overall prevalence of S. aureus was 29.17% in sheep milk, 31.67% in goat milk, 30% in humans, and 23.33% in environmental samples. The prevalence of E. coli was 17.5% in sheep, 23.33% in goats, 16% in humans, and 26.67% in the environment. Statistical analysis showed no significant differences in prevalence among sample sources (p > 0.05), indicating a uniform distribution across the animal–human–environment interface. Antimicrobial susceptibility profiling revealed widespread resistance among both pathogens. High resistance was observed against commonly used antibiotics, including ampicillin and oxytetracycline (P<0.05), which showed complete resistance across isolates. Ofloxacin exhibited moderate to high resistance depending on the source, particularly in environmental isolates. In contrast, fosfomycin and spiramycin showed comparatively better activity against E. coli, especially in goat-derived isolates. Overall, approximately 30% of samples were positive for S. aureus and 21% for E. coli, demonstrating their widespread occurrence. The study highlights the emergence of antimicrobial-resistant strains across animal, human, and environmental reservoirs. These findings emphasize the need for rational antibiotic use, continuous surveillance, and integrated One Health strategies to limit the spread of resistant pathogens across interconnected ecosystems.