MRSA Transmission between Cows and Humans

Abstract

We isolated methicillin-resistant Staphylococcus aureus (MRSA) from cows with subclinical mastitis and from a person who worked with these animals.The bovine and human strains were indistinguishable by phenotyping and genotyping methods and were of a low frequency spa type.To our knowledge, this finding indicates the first documented case of direct transmission of MRSA between cows and humans.S ince the introduction of β-lactamase-stable antimicro- bial drugs into clinical use, methicillin-resistant Staphylococcus aureus (MRSA) strains have emerged worldwide as important nosocomial pathogens; their prevalence in the community is increasing substantially.Although S. aureus is known to be one of the most common causes of bovine mastitis and other severe animal diseases such as septicemia and wound, bone, and joint infections, MRSA strains have been rarely isolated from animals.MRSA strains have been isolated from cows with mastitis, horses and dogs with lesions, and dogs and cats that were carriers (1).Transmission of MRSA between humans and animals (e.g., dogs, horses, pigs) has been reported (2-4), but transmission between cows and humans has not, to our knowledge.We describe a first putative case of transmission of MRSA between cows and a person.From January 2002through December 2004, 595 milk samples were collected from cows with subclinical mastitis on a farm in Hungary and sent for bacteriologic analysis to the Bacteriological Department of the Hungarian Central Veterinary Institute.Samples were streaked onto a Columbia agar plate (Merck, Darmstadt, Germany) containing 5% sheep blood and 0.01% esculin and a Baird-Parker (BP) agar plate (Oxoid Ltd., Basingstoke, England).After incubation at 37°C for 24 h, the colonies were tentatively identified according to morphologic features, pigment production, Gram stain results, catalase test results, type of hemolysis, and characteristic growth on BP