Subclinical mastitis in sheep: Causes and their sensitivity to antibiotics

The California mastitis test (CMT) was used to examine the milk of 6609 sheep, actually, from 13218 mammary complexes. A total of 986 milk samples were found to contain an increased number of somatic cells, and causes of mastitis were isolated from 910 (92.3%) of these samples. The most frequently isolated microorganisms were: E. coli isolated from 189 (20.76%) samples, Micrococcus sp from 186 (20.43%) samples, Bacillus sp. from 177 (19.45%), Staphylococcus aureus from 172 (18.9%) samples, and Proteus sp. from 121 (13.29%) samples of sheep milk. Coagulase-negative staphylococci (CNS) were isolated in a much smaller number, from 25 (2.74%) samples, Streptococcus sp. was isolated from 19 (2.08%) samples, Pseudomonas sp. from 14 (1.53%) samples, haemolytic E. coli was isolated from only 6 (0.65%) samples, and Streptococcus agalactiae from only one sample. Among the 25 isolates of coagulase-negative staphylococci, 16 (64%) isolates were identified as Staphylococcus chromogenes, and 9 (36%) isolates as Staphylococcus simulans. The sensitivity of the isolated causes of mastitis to antibiotics was examined using the disc diffusion method. .