Methicillin-resistant Staphylococcus pseudintermedius as causative agent of dairy cow mastitis.

Staphylococcus pseudintermedius is a coagulase-positive specie similar to Staphylococcus intermedius, frequently associated with pyoderma, otitis and urinary tract infections of dogs and cats (van Duijkeren and others 2011). No information about bovine mastitis caused by S pseudintermedius is available in the literature. Antimicrobial resistance among S pseudintermedius strains is increasing: in the past, susceptibility to most antibiotics was common (Bond and Loeffler 2012), but in the last few years methicillin-resistant S pseudintermedius (MRSP) strains have emerged as a significant animal health problem in veterinary medicine (Schwarz and others 2008, van Duijkeren and others 2008, Weese and van Duijkeren 2010). The methicillin-resistance of MRSP is mediated by the mecA gene, such as in Staphylococcus aureus (MRSA). The gene is located on a chromosomal mobile element (staphylococcal chromosomal cassette, SCCmec), which can be horizontally transferred (Weese and others 2010), raising concern about spreading of resistance among species and hosts (Bond and Loeffler, 2012). Therefore, the aim of this study was to report the occurrence of bovine mastitis by MRSP in a dairy herd and to investigate the characteristics of the isolates collected during a control programme for contagious pathogens.