drug resistance in isolated bacteria from milk of sheep and goats with subclinical mastitis in shahrekord district

four-hundred milk samples from half udders of 20 flocks of native breed goats were asepticallycollected. the samples were examined by california mastitis test (cmt). twenty-one (5.25%) of 400 werecmt-positive. the cmt-positive samples were then cultured and the following bacteria were isolated:staphylococcus aureus in 3 (14.28%), cns (coagulase-negative staphylococci) in 14 (66.66%), streptococciin 4 (19.04%) and mycoplasma spp. in 11 (52.38%) samples. the isolated staphylococci were examined toevaluate their resistance to different antibiotics by disc diffusion method. cns resistance to amikacin was78.5%, to penicillin was 50%, to tetracycline 50%, to ampicillin 42.8%, and to doxycycline was 28.5%.four-hundred native breed sheep milk samples were taken from 19 flocks in the same conditions. thesamples were examined by cmt test. 19 (4.75%) of 400 were cmt-positive. the cmt-positive sampleswere cultured and the following bacteria were isolated: s. aureus in 2 (10.5%), cns in 7 (36.8%),streptococci in 2 (10.5%), pasteurella in 1 (5.26%) and mycoplasma in 9 (47.37%) samples. the isolatedstaphylococci were examined for antibiotic susceptibility. cns resistance to amikacin was 42.8%, and totetracycline, ampicillin, oxycycline and penicillin was 14.3%. both isolates of s. aureus were resistance topenicillin.