Prevalence and Risk Factors of Multidrug Resistant (MDR) Escherichia coli Isolated from Milk of Small Scale Dairy Buffaloes in Rupandehi, Nepal

Abstract

Escherichia coli in untreated milk leads to economic losses from subclinical mastitis and reduced milk production, while also posing a public health risk due to the emergence of antimicrobial resistant strains, particularly associated with consuming unpasteurized milk and dairy products. This study aimed to determine the prevalence and antimicrobial resistance (AMR) of E. coli isolated from buffalo milk in Siddarthanagar Municipality of Rupandehi district, Nepal. A total of 102 milk samples were collected from lactating buffaloes. The isolation and identification of E. coli were carried out using enrichment media, selective media, and biochemical tests. Antimicrobial susceptibility testing was carried out using the Kirby–Bauer disk diffusion method on Mueller–Hinton agar (Merck), according to the Clinical and Laboratory Standards Institute (CLSI) recommendations. Resistance was tested against gentamicin, amikacin, ciprofloxacin, enrofloxacin, ceftriaxone, ceftazidime, cotrimoxazole, and chloramphenicol. In addition to this, farmers were administered a questionnaire consisting of both open- and close-ended questions to identify various animal-related and management-related risk factors associated with the prevalence of E. coli. The prevalence of E. coli in our study was 29.4% (n = 30/102). Ceftriaxone and ceftazidime showed 100% resistance, while cotrimoxazole and amikacin showed 86.7% and 80% resistance, respectively. Furthermore, 86.7% of E. coli isolates were multidrug resistant (MDR). Despite suggestive trends, associations between E. coli prevalence and risk factors lacked statistical significance, necessitating further research. While some antibiotics exhibited effectiveness, many faced resistance, highlighting the need for prudent antimicrobial usage and increased awareness among farmers. Raising awareness about milk pasteurization and implementing food safety practices is essential for ensuring farmers and public health.