Brief Informational Sketches of Some Other Mastitis Pathogens

Kansas State University College of Veterinary Medicine
Mississippi State University College of Veterinary Medicine
Virginia-Maryland Regional College of Veterinary Medicine
Texas A & M University College of Veterinary Medicine.

This site demonstrates our approach to evidence based antimicrobial dosing. As such, you should expect that features may change and content will increase with time. Although we believe the current information to be accurate, it is NOT complete and should NOT be used as a guide to therapy at this time .
We encourage you to contact us with questions or comments.

Mastitis Pathogen Information: Environmental Streptococci

Introduction: The Environmental Streptococci group is generally considered to encompass all Streptococci species other than Streptococcus agalactiae. There has been some debate about whether all other Streptococci, particularly Strep uberis, should properly be considered environmental pathogens, as transmission may occur directly from the environment or from the milking machine or milker's hands. S. uberis is the most common pathogen in the “environmental Streptococci” group. Other “environmental” species of Streptococcus include S. dysgalactiae, the Enterococci and other Streptococci. These bacteria are commonly found in the environment and on the skin of the teats.

Epidemiology / Clinical particulars:

Mastitis due to environmental Streptococci is common in herds where the contagious organisms Staphylococcus aureus and Streptococcus agalactiae are controlled. These infections commonly begin in the dry period and persist into early lactation. S. uberis is ubiquitous in the environment and can also be found in feces and on the cow's lips and tonsils. S. dysgalactiae can also be found in the tonsils and mouth of the cow, and also in the vagina and on the skin of the mammary gland. S. dysgalactiae infection of the mammary gland may predispose a cow to “summer mastitis” caused by Arcanobacter pyogenes. Cows may be exposed to these pathogens at any time: during milking, between milkings, during the dry period and even prepartum in heifers. Infection with environmental Streptococci is most common in the early or late dry period, in older cows, in the summer months, in cows already infected with Corynebacterium bovis, and in cows with teat injuries or chapping of the teat skin.

Clinical signs of environmental streptococcal mastitis are unremarkable. Milk is abnormal in appearance and there is generally some inflammation of the udder. Systemic signs of illness are not usually seen in environmental streptococcal mastitis. Mastitis due to this class of bacteria may spontaneously resolve, or it may become chronic, with or without treatment.

Diagnosis: Environmental Streptococci can be isolated by milk culture using standard laboratory methods and media.

Specifics of Therapy and Control:

In vitro susceptibility of the environmental Streptococci to antimicrobial drugs is high, and they frequently respond to appropriate therapy in vivo, also. However, Streptococcus uberis may invade mammary epithelial cells, evade phagocytosis and become a chronic infection despite therapy.

Environmental Streptococcal mastitis is best controlled using environmental cleanliness, standard mastitis control measures, and dry cow treatment. There is no commercially available vaccine against this family of bacteria.