Isolation ofStaphylococcus aureusand Coagulase-negative Staphylococci from Healthy and Mastitic Dairy-cow Mammary Glands and Production of Staphylococcal Enterotoxins and Toxic shock syndrome Toxin-1 by These Bacteria

Abstract

To isolateStaphylococcus aureus (S. aureus) and coagulase-negative staphylococci (CNS), examinations were made of mammary-gland secretions (MGS) from healthy and mastitic dairy cows at different stages of lactation. In the MGS of healthy mammary glands, throughout both lactating and nonlactating periods, S. aureusand CNS were detected at high levels near those observed in chronically infected mammary glands. MGSs were examined also for incidence and concentration of such staphylococcal enterotoxins (SEs) as SEA, SEB, SEC, SED, and SEE and for toxic shock syndrome toxin-1 (TSST-1). These toxins were detected at levels of nearly 50% in cultures of bothS. aureusand CNS. In the MGSs, incidences and amounts of SEC, though of neither the other SEs nor TSST-1, correlated well with degree of mammary-gland inflammation. These results strongly suggest that SEC may participate as a causal agent in subclinical staphylococcal mammary-gland infection causing apparent mastitis.