Prevalence of bacterial mastitis in cattle from the farms around Tehran

Document Type : Short paper


1 Department of Clinical Sciences, Faculty of Veterinary Medicine, University of Tehran, Tehran, Iran

2 Department of Food Hygiene and Public Health, Faculty of Veterinary Medicine, University of Tehran, Tehran, Iran


To determine the prevalence of bacterial mastitis in cattle, milk samples positive for California mastitis
test (CMT) were cultured during a period of almost 4 years. The bacterial species isolated from 2904 milk
samples studied were coagulase negative Staphylococcus sp. in 879 (30.27%) samples, Streptococcus
agalactiae in 642 (22.11%), S. dysgalactiae in 332 (11.43%), E. coli in 295 (10.16%), Staphylococcus aureus
in 84 (2.89%), Bacillus cereus in 51 (1.76%), Arcanobacterium pyogenes in 31 (1.07%), Pseudomonas
aeruginosa in 6 (0.21%), Klebsiella pneumoniae in 4 (0.14%), Pasteurella multocida in 1 (0.03%) and
Mycoplasma sp. in another (0.03%) sample. No growth was found in 578 samples (19.90%). Thirty-one
(37%) of 84 animals which were infected with S. aureus, had acute infection. We found that contamination
of milk with coagulase negative staphylococci are the most frequent bacterial infection in dairy cattle around
Tehran; it mostly causes subacute form of the disease. S. agalactiae, S. dysgalactiae and E. coli are the
second, third and the fourth causative agents.