Prevalence of bovine mastitis and antimicrobial sensitivities of the bacterial causes in smallholder farms of Kisumu County, Kenya

Prevalence of bovine mastitis in Kisumu County, risk factors and antibiotic sensitivities of the causative bacteria were determined in this cross-sectional study. Sub-clinical mastitis (SCM) was diagnosed using California Mastitis Test (CMT). Risk factors were identified through the administration of 64 questionnaires and assessment of 134 lactating cows. Bacteria were identified by culturing 72 CMT-positive udder quarter milk samples and their sensitivities to antibiotics investigated using Kirby-Bauer disc diffusion test. Only SCM was detected and had cow level prevalence of 33% (44/134). Prevalence of SCM was significantly (p<0.05) higher in cows under complete and semi-zero grazing systems, at mid lactation, those pregnant and with parity of 1-3. Staphylococcus species was the most common (63.8%, n=58) isolate. Other isolates were E. coli (13.8%), Streptococcus species (12.1%) and Pseudomonas (5.2%). Staphylococcus and Streptococcus isolates were 100% sensitive to streptomycin, kanamycin, gentamycin and chloramphenicol. Additionally, Streptococcus species were 100% sensitive to ampicillin, tetracycline and cotrimoxazole. Staphylococcus species had developed varying levels of resistance against sulphamethoxazole, cotrimoxazole, ampicillin and tetracycline. Streptococcus species was 100% resistant to sulfamethoxazole. A significantly high SCM prevalence was reported in this study thus an appropriate control strategy is needed that consists of awareness creation, good milking hygiene practices, teat disinfection, regular screening for SCM and preventing spread of mastitis in the herd by milking infected cow(s) last.