Intramammary infections in a dairy herd with a low incidence of Streptococcus agalactiae and Staphylococcus aureus infections.
In a dairy herd with a low incidence of intrammary infections due to Streptococcus agalactiae and Staphylococcus aureus, clinical mastitis remained a serious problem despite good control of nonclinical mastitis through postmilking teat disinfection and antibiotic therapy of known infected quarters at the end of lactation. During the 2-year study, the incidence of clinical mastitis was 0.88 cases/cow-year; 32.2% were caused by streptococcal species other than Str agalactiae and 33.5% by gram-negative organisms. Among all new infections detected, 54.1% were caused by streptococcal species other than Str agalactiae and 25.7% by gram-negative bacteria. Among new infections, 41.6% occurred during the nonlactating period or within a few days of calving. Incidence of clinical mastitis was highest in the 1st month of lactation. Among 84 gram-negative infections, 42.8% were caused by Klebsiella pneumoniae, 20.2% by Escherichia coli, and 23.8% by Enterobacter spp. Among the many serotypes of K pneumoniae and E coli, none was predominant.
D000818:Animals; D002417:Cattle; D005260:Female; D007710:Klebsiella Infections / Q000453:epidemiology / Q000662:veterinary; D007711:Klebsiella pneumoniae; D007774:Lactation; D008414:Mastitis, Bovine / Q000453:epidemiology*; D011247:Pregnancy; D013203:Staphylococcal Infections / Q000453:epidemiology / Q000662:veterinary*; D013211:Staphylococcus aureus; D013290:Streptococcal Infections / Q000453:epidemiology / Q000662:veterinary*; D013292:Streptococcus agalactiae