Bovine Mastitis: Staphylococcus aureus isolation and identification from Small holder Dairy Farms located in and around Hawassa town, Southern Ethiopia

Abstract

Mastitis is a widely distributed disease of dairy cattle in most countries, including Ethiopia. The most commonly recovered bacterial pathogen during mastitis is Staphylococcus aureus in dairy cows worldwide.With this, a cross-sectional study was conducted from March 2021 to August 2021 on dairy farms in and around Hawassa town to isolate and identify Staphylococcus aureusfrom bovine mastitis milk and to determinerisk factors associated with the occurrence of mastitis. A total of 250 lactating cows wererandomly selected for clinical and subclinical mastitis from 29 small holder dairy farms.Clinical signs and the California Mastitis Test (CMT) were used to identify clinical andsubclinical mastitis, respectively. Accordingly, a standard bacteriological study targetingS. aureus was conducted with all (n=127) milk samples collected from clinical andsubclinical mastitis cows. Data generated from these methods were analyzed usingSTATACorp. Version 12. Association between the risk factors and mastitis weredetermined with p<0.05 to be a statistically significant one. During the study period,50.8% of cows had mastitis, of which 4.8% and 46% showed clinical and subclinicalmastitis, respectively. The quarter-level proportion was 27.4%; of which the clinical formwas 2.9%, while the subclinical mastitis was 24.5%. Logistic regression analysis showed asignificant association among cows of different age groups, lactation stages, andfrequency of farm cleaning status per day with the occurrence of mastitis (p < 0.05).Bacterial identification targetingS. aureuswas done, and this agent was identified in 60(47.2%) milk samples. This pathogen was found to be higher (47.8%) in subclinical thanin clinical (41.6%) mastitis. In conclusion, this study showed that mastitis was prevalent indairy cattle of the study area, with a higher case of S. aureus in subclinical mastitis.However, the detection of S. aureus in nearly half of the milk sample collected frommastitic cows indicated the possible presence of other pathogens. Therefore, further studyto recoverother potential pathogens commonly causing mastitis can be a good approach.