Farm-Level Factors Associated With Multidrug-Resistant Escherichia coli and Klebsiella spp. in Bulk Tank Milk in Tigray, Northern Ethiopia

Abstract

Raw milk is widely consumed unpasteurized in Ethiopia, posing food safety risks when contaminated with multidrug-resistant (MDR) bacteria. This study investigated farm-level factors associated with the occurrence of MDR Escherichia coli and Klebsiella spp. in bulk tank raw milk from dairy farms in the Tigray region, Northern Ethiopia. A cross-sectional study was conducted among 178 dairy farms, combining microbiological analysis of bulk tank milk with data on farm hygiene, animal health, and antimicrobial use (AMU) practices. A total of 119 isolates (70 E. coli and 49 Klebsiella spp.) were recovered, of which 32.8% were classified as MDR. Multivariable analysis showed that infrequent washing of milking utensils (once daily or less) was strongly associated with MDR-positive milk (adjusted odds ratio [AORs] = 7.41; 95% CI, 1.94–28.31). Self-administration of antimicrobials by farm owners (AOR = 3.73; 95% CI, 1.48–9.39) and a history of mastitis in the herd (AOR = 4.79; 95% CI, 1.39–16.52) were also independently associated with MDR occurrence, while herd size was not significantly associated. The presence of MDR E. coli and Klebsiella spp. in raw milk represents a significant food safety concern in smallholder dairy systems. Targeted interventions focusing on improved milking hygiene, responsible AMU under veterinary supervision, and effective mastitis management are essential to reduce the entry of resistant bacteria into the dairy value chain and limit consumer exposure.