Etiology and antimicrobial resistance of bovine mastitis pathogens in North-Eastern Zimbabwe: Emerging threats and management gaps

Abstract

Bovine mastitis, a significant challenge for dairy farming in Zimbabwe, affects milk production, animal health, and economic viability. This study investigated the etiology, prevalence and antimicrobial resistance of mastitis pathogens in dairy farms in the north-eastern regions of Zimbabwe. Of the 256 cows tested, 36.3% showed signs of mastitis, predominantly subclinical (28.1%). Key pathogens isolated included Staphylococcus spp. (34.4%), Streptococcus spp. (26.9%), and Escherichia coli (18.3%). Notably, Candida spp. and Corynebacterium bovis were identified for the first time as mastitis pathogens in Zimbabwe. The detection of Candida spp. underscores the impact of prolonged antibiotic use, which disrupts bacterial flora and promotes fungal infections, while the presence of Corynebacterium bovis highlights hygiene deficiencies in milking practices. Alarmingly, 25% of Staphylococcus isolates were multidrug-resistant (MDR), including methicillin-resistant Staphylococcus aureus (MRSA). Resistance to commonly used antimicrobials such as tetracycline and trimethoprim-sulfamethoxazole was widespread, further complicating treatment options. This study emphasizes the need for improved hygiene practices, routine screening, and antimicrobial stewardship to manage mastitis and curb the spread of resistance.