CliniCal and epidemiologiCal aspeCts of Cow mastitis Caused by StaphylococcuS aureuS and its methiCillin-resistant strains

Mastitis represents one of the most important problems in modern dairy production from the economic, diagnostic and public-health related point of view. Economic significance of the mastitis is related to the decreased milk production, lower quality of the milk, veterinary expenses and withdrawing of the milk due to the antibiotic treatment. Detection of mastitis is often complicated due to the subclinical nature of the mammary infection in which the increase of the somatic cells is only sign of the infection. Public health importance rises from the possibility of the transmission of zoonoses as well as due to the residue of the antibiotics secreted by milk. Staphylococcus aureus is the most commonly isolated udder pathogen around the world. Since it is contagious, critical time for spreading among the cows in a herd is the milking time. Observed prevalence of S. aureus mammary gland infection varies from 2% to 50% even above and depends on the milking hygiene. Clinical manifestations of the S. aureus mastitis may vary from mild cases with elevated somatic cells only to the gangrenous cases with lethal exit. Methicillin-resistant staphylococci as mastitis pathogens were first identified in the 1972. During the last decade methicillin-resistant Staphylococcus aureus (MRSA) was identified as a mastitis pathogen in few occasions in Belgium, Poland, Hungary and Germany. Spreading of the MRSA between animals and humans is documented. Although the prevalence of mammary gland infection caused by MRSA is low, there is thread of spreading of the MRSA among herds by animal trade. Spreading within the herd is enabled with large number of possible contacts between cows by milkers and milking equipment.