ANTIMICROBIAL TREATMENT STRATEGIES FOR STREPTOCOCCAL AND STAPHYLOCOCCAL MASTITIS

摘要

Mastitis is one of the most costly diseases encountered by dairy producers. Traditional therapy aimed at curing clinical mastitis cases includes intramammary (IMM) antimicrobial therapy. In spite of multiple available IMM antimicrobial products, curerates for clinical mastitis run about 46% for Streptococcus spp, 21% for Staphylococcus spp, and 9% for Staphylococcus aureus mastitis (1). This study investigated the use of systemic antimicrobial therapy (ampicillin) in conjunction with IMM antimicrobial therapy for Strep spp, Staph spp., and Staph aureus. Milk from lactating Holstein cows with clinical mastitis from a 3,000-cow dairy herd was cultured on sheep blood agar. All cows with a Strep spp(n=80), Staph spp.(n=60), or Staph aureus (n=25) positive culture result were enrolled in the trial and assigned one of three treatments based on a randomized six-block table. For Strep spp., cows were grouped as not treated, treated with IMM amoximast once a day for five days, or treated with IMM amoximastplus 30 cc ampicillin IM once a day for 5 days. For Staph spp and Staph aureus cows were grouped as not treated, treated with IMM pirsue once a day for five days, or treated with IMM pirsue plus 30 cc amplicillin IM once a day for 5 days. One milk sample was collected and cultured from the affected quarters 21-28 days after completion of antimicrobial therapy. A cow was considered cured if there was no growth at the 21-28 day culture. Days until clinical cure, days in hospital, somatic cell count (SCC), milk production, previous mastitis events, lost quarters, and whether the cow was sold/died were all recorded.