MANNITOL AGAR FOR MICROBIOLOGIC DIAGNOSIS OF BOVINE MASTITIS

  • 1 January 1981
    • journal article
    • research article
    • Vol. 178  (10) , 1061-1064
Abstract
A medium containing mannitol (manntiol agar) was developed and evaluated as a tool for the microbiologic diagnosis of bovine mastitis. Mannitol agar supported growth of all important bacterial mastitis pathogens (staphylococci, streptococci, coliforms and pseudomonads) except Corynebacterium pyogenes. Color change around colonies in the agar permitted the differentiation of pathogenic from nonpathogenic staphylococci. Most Staphylococcus aureus strains and some S. epidermidis strains produced yellow zones. These yellow zone-producing strains (mannitol fermenters) of staphylococci were obtained from quarters with significantly elevated (P < 0.05) somatic cell counts (SCC) in the milk, as compared with uninfected quarters and, thus, would be considered pathogens. Mannitol-negative strains of S. epidermidis (those with red zones) were obtained from quarters with SCC similar to those of uninfected quarters. The streptococci could be divided into 2 groups on the basis of color change around the colonies: S. agalactiae, S. dysgalactiae and group G streptococci produced red zones; S. uberis, S. bovis and enterococci produced yellow zones. Pathogenic streptococci (S. agalactiae, S. dysgalactiae, S. uberis and group G streptococci) were obtained from quarters with SCC significantly higher (P < 0.01) than those of uninfected quarters S. bovis and enterococci were obtained from quarters with SCC similar to those of uninfected quarters and were considered nonpathogenic. Pathogenic streptococci were found in much higher concentration than nonpathogenic streptococci and could be differentiated on that basis.