Staphylococcus pseudintermedius: Population Genetics and Antimicrobial Resistance

Staphylococcus pseudintermedius is a Gram-positive coagulase-negative coccus. It is a normal inhabitant of the skin of dogs. However, clinical disease can be observed in animals that are immunossuppressed or if the skin barrier is altered. This bacterium is recognized as the main cause of canine pyoderma and has also been associated with other conditions such as infection of the urinary tract, the ears, and surgical wounds.

Methicillin resistance and resistance to other antimicrobials regularly used by veterinarians is common among S. pseudintermedius which can complicate treatment. The first report of mecA, gene responsible for methicillin resistance, in S. pseudintermedius is from 1999. Since then, resistance to methicillin and to other antimicrobials has become increasingly more common, making this bacterium a possible reservoir for antimicrobial resistance genes. The reason for the increase in the presence of antimicrobial resistance among S. pseudintermedius is still not well understood.

This research focuses on characterization of S. pseudintermedius isolates from the United States in order to determine their genetic diversity, antimicrobial susceptibility profiles, and possible relationships among the two. A description of the genetically related populations that are present in the country may help in the understanding of the mechanisms of expansion of this microorganism. Also, the availability of more current information on the susceptibility to antimicrobials should help in the reestablishment of the consequences of misusage of antimicrobials and highlights the need for the development of novel treatment alternatives.