New categories designated as healthcare-associated and community-associated methicillin-resistant Staphylococcus pseudintermedius in dogs.

Abstract

The incidence of MRSP has been increasing, and treatment options in veterinary medicine are limited. Few previous studies of MRSP have described the relationships between the genotypes, phenotypes, and clinical backgrounds of the isolates. To gain insight into the associations between the microbiological and clinical characteristics of MRSP, we analyzed 282 Staphylococcus pseudintermedius isolates from dogs. A total of 195 (69.1%) strains were identified as mecA-positive MRSP and were classified into mainly two genotypes: SCCmec types III (II-III) (52.8%) and V (37.4%). SCCmec type III MRSP strains were significantly correlated with hospital admission and antimicrobial therapy of the dogs, and exhibited a homogeneous genotype similar to sequence type 71-MRSP, which is a globally endemic clone in dogs. In contrast, SCCmec type V MRSP strains were not highly correlated with hospital admission and antimicrobial therapy and exhibited genotypic and phenotypic heterogeneity. Properties of MRSP strains SCCmec types III and V were similar to those of HA- and CA-MRSA, respectively. Therefore, we designated these isolates carrying SCCmec types III and V as HA-MRSP and CA-MRSP, respectively. Discrimination between HA- and CA-MRSP by oxacillin MIC will provide useful information for treatment and infection control measures for canine MRSP infections.