Surveillance of healthy cats and cats with inflammatory skin disease for colonization of the skin by methicillin-resistant coagulase-positive staphylococci and Staphylococcus schleiferi ssp. schleiferi.

In this study, bacterial cultures were collected from five sites on each of 50 healthy cats and 48 cats with inflammatory skin disease (ISD), to determine prevalence of carriage and relative frequency of methicillin resistance in coagulase-positive staphylococci and Staphylococcus schleiferi ssp. schleiferi. Latex agglutination testing for penicillin-binding protein 2a (PBP2a) and pulsed field gel electrophoresis (PFGE) were performed on all methicillin-resistant (MR) isolates. Polymerase chain reaction (PCR) for the mecA gene was performed on MR S. intermedius and S. schleiferi isolates. Staphylococcal chromosomal cassette (SCCmec) typing was performed on all MR S. aureus isolates. Coagulase-positive staphylococci and S. schleiferi ssp. schleiferi were isolated from 24 of 48 cats with ISD: Staphylococcus aureus (14 of 24, 58%), Staphylococcus intermedius (11 of 24, 46%), Staphylococcus schleiferi ssp. schleiferi (1 of 24, 4%), and Staphylococcus hyicus (1 of 24, 4%). Prevalence of MR was 7% for S. aureus, 0% for S. intermedius, 100% for S. schleiferi ssp. schleiferi, and 0% for S. hyicus. Coagulase-positive staphylococci were isolated from 17 of 50 healthy cats: S. aureus (10 of 17, 59%), S. intermedius (11 of 17, 65%), and S. schleiferi ssp. coagulans (1 of 17, 6%). Prevalence of MR was 20% for S. aureus, 18% for S. intermedius, and 0% for S. schleiferi ssp. coagulans. All MR isolates were positive for PBP2a via latex agglutination. Methicillin-resistant S. intermedius and S. schleiferi ssp. schleiferi isolates were also positive for the mecA gene via PCR. Methicillin-resistant S. aureus isolates were identified as SCCmec type II. Results of PFGE indicated heterogeneity among isolates. There was no significant difference in staphylococcal isolation or methicillin resistance between study groups. While present, MR coagulase-positive staphylococci are significantly less common in these study populations.