Antibiotic Susceptibility of Mastitogenic Bacteria Isolated From Clinical Mastitis Cows in Midlands Province, Zimbabwe

Abstract

Mastitis is a global challenge for the dairy industry and mastitogenic bacteria play a critical role among other causes. Many mastitogenic bacteria are becoming resistant to single or combination antibiotic therapy, making mastitis cases difficult to cure. Nevertheless, there is insufficient evidence on the occurrence and antibiotic resistance patterns of mastitogenic bacteria in commercial dairy and communal farms in the Midland Province of Zimbabwe that might support a holistic approach to mastitis mitigation. A cross-sectional study aimed to isolate and evaluate the antibiotic susceptibility patterns of mastitogenic bacteria from cattle with clinical mastitis was conducted. A total of 164 milk samples were analyzed, of which 36.6% (60) samples were collected from commercial farmers, and 63.4% (104) came from communal farmers. The samples were cultured on standard media and sensitivity patterns of the identified bacteria were tested against 14 antibiotics using the Kirby-Bauer disc diffusion method. All milk samples from communal farms were positive for mastitogenic bacteria compared to 88% (53) of mastitogenic positive milk samples from commercial farms. The most common microorganisms from all the 157-mastitogenic positive milk samples were Staphylococcus aureus (37.5%) and Escherichia coli (23.3%). The highest resistance was observed against Penicillin, Erythromycin, Ampicillin, and Lincomycin, whereas most isolates were susceptible to Sulphamethoxazole, gentamycin, neomycin, kanamycin, cloxacillin, ertapenem, ceftriaxone, Amp-Ampicillin, amikacin, vancomycin, and tetracycline. Futher research to investigate the significance of resistant mastogenic bacteria in terms of Veterinary costs, production losses and potential public health transmission of antibiotic resistant mastogenic bacteria is recommended