Isolation, identifications and antimicrobial susceptibility pattern of coagulase positive Staphylococcus from subclinical mastitic dairy cattle in and around Haramaya University

Abstract

A cross-sectional study was conducted from November 2013 to April 2014 to isolate coagulase positive Staphylococcus (CPS) from subclinical mastitic (SCM) lactating cows, to establishing prevalence, to identify risk factors and to determine the antimicrobial susceptibility pattern of CPS isolates in and around Haramaya University, Eastern Ethiopia. A semi-structured questionnaire survey, California mastitis test (CMT), bacterial isolation and identification and in vitro antimicrobial susceptibility tests were conducted during the study. A total of 210 dairy cattle from seven farms were screened for SCM by CMT. The prevalence of SCM in the study areas was 71.4% (150/210). Milk samples were collected from 562 quarters of 150 cows free of clinical mastitis but positive in CMT. Among these cows 38 of them had blind quarters (6. 76%). The prevalence of CPS was found to be 66.0% (99/150) and 28.46% (160/562) on animal and quarter basis, respectively. Among the risk factors studied, SCM due to CPS was significantly higher (P > 0.05) in older cows (100%) than younger (70.0%), in cows during late lactation (96.3%), in cows which gave more than 5 births (100%), in cross-breed cows (71.2%) than local breed cows (54.3%), in cows with udder I teat injuries (96.3%) and in cows managed under poor house hygiene (82.5%). Antimicrobial susceptibility testing of 9 antibiotics carried out using Kirby-Bauer disc diffusion method and revealed high multidrug resistance of 71 (87.6 %). High level of resistance to common drugs like ampicillin (90.1 %), penicillin (67.9%), and tetracycline (54.3%) was registered. In contrast, the CPS isolates were susceptibility for chloramphenicol, gentamycin and kanamycin at 63%, 46.9%, and 41.97%, respectively. In conclusion, the study confirms the importance of CPS as a mastitis causing multidrug resistant bacterium. Therefore, improved management and early treatment of SCM cases with drug of choice is imperative to tackle CPS mastitis.

Keywords: Antimicrobial susceptibility, Coagulase positive Staphylococcus, and risk factors