PREVALENCE, ASSOCIATED RISK FACTORS, AND ANTIMICROBIAL SENSETIVITY TEST OF STAPHYLOCOCCUS AUREUS ISOLATED FROM BOVINE MASTITIS IN BABILE DISTRICT EASTERN HARARGHE ZONE, ETHIOPIA

Abstract

Mastitis is a disease of major economic importance in dairy industry worldwide particularly in Ethiopia. A cross-sectional study was carried out from August 2021 to March 2022 to determine the prevalence and associated risk factors of bovine mastitis and antimicrobial sensitivity test of S. aureus isolates in Babile district, eastern Ethiopia. A total of 384 lactating cows managed under extensive production systems were selected from three selected kebeles of Babile district. California mastitis test (CMT) was used for screening subclinical mastitis. Likewise, physical examination was also conducted to detect clinical mastitis. Out of the total animals examined, 50.5% (194/384) had mastitis, where 5.5% (21/384) and 45% (173/384) were clinical and subclinical mastitis respectively. The quarter-level prevalence was 19.01% (292/1536), from which the clinical and subclinical form was 2% (32/1536) and 11.97% (184/1536) respectively, whereas 2.7% (42/1536) of the quarters were blind. Milk samples from positive quarters were cultured to isolate S. aureus using standard bacteriological test; accordingly, 30.9% of sample showed growth of S. aureus. Among the risk factors analyzed using a univariable logistc regression analysis, except lactation stage, all factors such as kebeles, age, parity, body condition, udder size, milk yield, tick infestation and teats injury were found to be statistically significant with the occurrence of mastitis (p < 0.05). However, using multivariable logestic regression analysis udder size, tick infestation and teat injury were significantly associated the occurrence of bovine mastitis in the study area while the other remaining factors were not significant. Antimicrobial sensitivity test results of the 35 S. aureus isolates showed that, 100% susceptible to chloramphenicol and gentamycin. In contrast, the highest (94.2%) resistance was observed for penicillin G followed by amoxicillin (28.57%) and Erythromycin (20%). The study confirmed S. aureus was an important cause of bovine mastitis particularly related to potential risk factors and significant number of S. aureus isolates showed resistance against some chemical drugs in the study area. Hence, it warrants serious attention for the control of mastitis considering the risk factors and alternative treatment options