Determination of some characteristics of environmental streptococci isolated from milk samples of sub clinical mastitis cows in Shahrekord district

Bovine mastitis is the most costly disease affecting dairy cattle breeding as it occurs very frequently and reduces milk production. Streptococci are frequently isolated from bovine mastitis in dairy cows. The present investigation was carried out to determine some phenotypic characteristics of the environmental streptococci species isolated from bovine sub clinical mastitis cases in dairy farms of Shahrekord district in west of Iran. 180 CMT positive milk samples were bacteriologicaly studied. A total of 61 environmental streptococci isolated, S. dysgalactiae (43 isolates), S. uberis (10 isolates) and E. faecalis (8 isolates) were the prevalent identified species. Production of biofilms was 86%, 90% and 37.5% for S. dysgalactiae, S. uberis and E. faecalis respectively. 7 isolates of S. dysgalactiae (16.3%) were positive in DNAase test. Only 37.5% of S. dysgalactiae and 25% of E. faecalis strains were susceptible to kanamycin. For streptomycin, the sensitivity of all species was less than 16%.