MASTITIS PATHOGENS | Contagious Pathogens

Abstract

Contagious pathogens include Staphylococcus aureus , Streptococcus agalactiae , Mycoplasma bovis , and Corynebacterium bovis , which are spread from infected to uninfected quarters during milking. Streptococcus agalactiae are spherical Gram-positive bacteria that grow in chains and are shed in very high numbers in milk from infected quarters. This microorganism is sensitive to penicillin and can be eradicated from dairy herds. Staphylococcus aureus are Gram-positive bacteria that grow in grape-like clusters. Once S. aureus establishes an infection, a chronic inflammation results along with elevated somatic cell counts (SCCs); infections are extremely difficult to cure with antibiotics because of the development of scar tissue. Mycoplasma species do not stain with Gram stain and are intermediate in size between bacteria and viruses; mastitis caused by Mycoplasma should be suspected when milk samples from cows with clinical symptoms (often in multiple quarters) are negative after repeated culture. Corynebacterium bovis are Gram-positive, club-shaped bacteria; the resulting infections with these bacteria are usually mild with a slight elevation in SCC. All contagious organisms, with the exception of Mycoplasma , are prevented by proper udder hygiene, correct use of milking machines, teat dipping after milking, and use of nonlactating cow therapy. Control of Mycoplasma is achieved through the prevention of new infections based on screening, herd replacements, and use of rigid milking hygiene, because treatment is ineffective.