Dr. Christine Minoo Mbindyo

Bovine mastitis: Establishing bacterial diversity, associated risk factors and Antimicrobial resistance profiles of the isolates in Kajiado and Embu Counties, Kenya. 

Despite the global challenge of bovine mastitis, studies on prevalence, bacterial diversity of mastitis-causing pathogens, risk factors and antibiotic resistance profiles of the isolate in dairy cows in Kenya remain limited. This cross-sectional study was undertaken in Embu and Kajiado counties of Kenya where 395 randomly selected dairy cows from 154 smallholder farms. In each of the farms, a semi-structured questionnaire was used to collect data on mastitis management practices and cow level risk factors associated with mastitis. California Mastitis Test (CMT) was used to screen the milk before being analyzed for bacterial infection using standard bacterial culture methods. Further 16S rRNA metagenomics analysis was done to determine bacterial diversity in culture negative mastitic milk samples. Disc diffusion method, (PCR) amplification and partial sequencing was used to determine the phenotypic and molecular antimicrobial susceptibility profile of the isolates. 

Overall, prevalence of mastitis at cow level was 81.2%, out of which 6.8% was clinical mastitis, while 74.4% was subclinical mastitis. On culture, CNS at 42.8% were the dominant bacteria. Failure to milk mastitic cow last and previous history of mastitis cases were associated with mastitis. Increased relative abundance of genera Chlamydia and Solibacillus in culture-negative mastitic. Highest Antimicrobial resistance (AMR) among the isolates was reported in ampicillin (75%-66%). Staphylococci isolates revealed that blaZ at 44.3% was the most common AMR genes.

This study shows high prevalence of subclinical mastitis, dominated by CNS and increased relative abundance of Chlamydia and Solibacillus in culture negative. High resistance to beta lactams with blaZ genes was reported. Therefore, proper control measures should be put in place in affected farms.