Abstract: Among the animal diseases that require antibiotic treatment in dairy herds, mastitis is the commonest one. As a consequence antimicrobial resistance of mastitis pathogens has received recent attention. The purpose of this study was to describe and compare antimicrobial susceptibility of mastitis pathogens isolated on 322 local and crossbred lactating hand milked small holder cows. The major bacteria isolated in this study were Staphylococcus aureus (n = 27), Coagulase-Negative Staphylococci (CNS) (n = 51), Streptococcus agalactiae (n = 26), Streptococcus dysgalactiae (n = 23), Streptococcus uberis (n = 11), Micrococcus sp. (n = 12), Corynebacterium bovis (n = 4), Actinomyces pyogenes (n = 2), Bacillus cereus (n = 1) Escherichia coli (n = 7). Staphylococcus aureus was found to be highly sensitive to five of the antimicrobials tested where the bacteria had shown 100% susceptibility to kanamycin and sulfisoxazole. However, Coagulase negative staphylococci had revealed different levels susceptibility for only four of the nine antimicrobials tested. Streptococcus agalactiae was highly susceptible to sulfisoxazole (100%), clindamycin (100%) and susceptibility to streptomycin was 50%. Similarly, all other bacteria isolated demonstrated different level of susceptibility to the tested antimicrobials. In general it was found that sulfisoxazole was the most effective antibiotic where 91.07% of the total isolates were found susceptible followed by clindamycin and kanamycin with susceptibility of (89.28%) and (88.4%), respectively. The least effective antibiotics were streptomycin (45.5%), ampicillin (49.1%). Tetracycline, erythromycin, chloramphenicol and oxacllin have susceptibility of 65.2, 59.8, 64.3 and 58.04%, respectively.
Nibret Moges, Yilikal Asfaw, Kelay Belihu and Abebayehu Tadesse, 2011. Aantimicrobial Susceptibility of Mastitis Pathogens from Smallholder Dairy Herds in and Around Gondar, Ethiopia. Journal of Animal and Veterinary Advances, 10: 1616-1622.