Antimicrobial susceptibility of coagulase-negative staphylococci isolated from bovine mastitis between 2003 and 2008 in Korea.

A total of 1,444 coagulase-negative staphylococci (CNS) isolates from bovine mastitic milk samples collected during 2003-2008 in Korea were identified to the species level. Of 14 species identified, S. simulans, S. haemolyticus, and S. sciuri accounted for over 60% of the isolates. All the CNS isolates were tested for susceptibility to eight antimicrobials commonly used in dairy cattle. With a few exceptions, similar resistance patterns were observed among the CNS species: penicillin and ampicillin showed the lowest activity while amikacin, cephalothin, and gentamycin were highly effective. About 39% (557/1,444) of the CNS isolates were pan-susceptible, while 12% (175/1,444) showed resistance to four or more antimicrobials tested.