Isolation and Identification of Methicilin Resistant s. Aureus from Bovine Mastitic Milk in Dairy Farms of Bahir dar and Its Surrounding North West Ethiopia
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Date
2015-06
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Addis Ababauniversity
Abstract
Staphylococcus aureus is a common causative agent of bovine mastitis in dairy herds. The emergence of Methicillin-Resistant Staphylococcus aureus (MRSA) in dairy farms is significant and costly public health concern. S. aureus bovine mastitis is a common reason for therapeutic and/or prophylactic use of antibiotics on dairy farms. A cross sectional study was conducted from November 2014 to April 2015 in and around Bahir Dar Town, to isolate and identify Methicillin Resistant S.aureus, their resistance pattern to different antimicrobials and to identify risk factors associated with mastitis. A total of 311 lactating local (Fogera) and Crossbreed cows were included during the study period, and total of 1244 quarters were examined to detect clinical and subclinical mastitis by physical examinations of udder, milk and by California Mastitis Screening Test. The overall prevalence of mastitis at cow level was 62.06 % with 3.54% and 58.52 % of clinical and subclinical mastitis prevalence respectively. From a total of 1244 quarters examined, 4.82% were blind teats, 1.93 % and 40.51 % of quarters were affected by clinical and subclinical mastitis respectively. In this study, the subclinical mastitis was higher than clinical mastitis. The occurrence of mastitis varied significantly (p<0.05) between cross breeds and local Fogera breeds by 78.64% and 29.52% respectively. The univariate logistic regression showed that among potential risk factors considered from the farm attributes, breed, age, farm floor type and previous treatment history had significant (p < 0.05) effect on the prevalence of mastitis. However, lactation stage, parity and milking hygiene were not a significant (p > 0.05) potential risk factors. From 193 mastitis infected lactating cows, 528 milk samples were cultured and twenty-nine Staphylococcus aureus were isolated. The isolated S.aureus was tested with eight different types of antibiotics to identify their resistance pattern. The present result showed a significant association of resistance, particularly to penicillin G 95.8%, streptomycin 73.1%, tetracycline 72.2%, amoxicillin 61.5% and vancomycin 52.4%. In this study, 75.7 % S. aureus isolates were resistant for Cefoxtin, which is an indication of existence high level of MRSA prevalence. There were also observed resistance for other multidrugs, mainly to penicillin G, streptomycin and tetracycline because of production of β-lactamase and inactivate potency of antibiotics. The present study revealed higher prevalence of mastitis and occurrence of multidrug
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resistance S. aureus specifically which belongs to the MRSA which are dependent on multiple associated risk factors. S. aureus to various antibiotics indicated that existence of alarming level of resistance of frequently isolated mastitis bacteria to commonly used antimicrobial agents in the study area. Hence, regular resistance follow-up, using antimicrobials sensitivity tests helps to select effective antibiotics and to reduce the problems of drug resistance developments towards commonly used antimicrobials.
Key words: Antimicrobial susceptibility, Dairy, Mastitis, MRSA, Multidrug resistant, S. aureus
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Keywords
Antimicrobial susceptibility, Dairy, Mastitis, MRSA, Multidrug resistant S, aureus