Methicillin‐resistantStaphylococcus pseudintermedius(MRSP) from healthy dogs in Norway – occurrence, genotypes and comparison to clinicalMRSP

Abstract

AbstractThe aim of the study was to investigate the occurrence of methicillin‐resistantStaphylococcus pseudintermedius(MRSP) in healthy dogs and further to determine genetic relatedness between carrier isolates and clinicalMRSPfrom dogs in Norway. A total of 189 healthy dogs visiting ten veterinary clinics were screened forMRSPduring the period February to April 2013. Carrier isolates were susceptibility tested with disk diffusion and genotyped using multilocus sequence typing (MLST) and pulsed‐field gel electrophoresis (PFGE). Forty‐nine clinicalMRSPwere characterized for comparison. These isolates were collected from July 2008 to April 2013 and represent allMRSPindex isolates from eachMRSP‐positive dog detected in Norway until April 2013. Geographical distribution of allMRSPcases was investigated using the ArcGIS9.3 Software.MRSPwas detected from five (2.6%) healthy dogs, sampled at three different clinics. The isolates grouped into three sequence types (STs):ST252 (two isolates),ST71 (two isolates) andST306 (one isolate).MRSPfrom dogs sampled at the same animal clinic belonged to the sameSTand produced identicalPFGEpattern. The 49 clinicalMRSPgrouped into 15STs;ST258 (n = 17),ST71 (n = 10), andST305 (n = 4) were the most prevalent. TheMRSPcarrier isolates were genetically related toMRSPvariants from dogs with infections asST306 (from a carrier) is related toST258.MRSP ST252, found in two carriers, was also present among the clinicalMRSPisolates. Altogether theMRSPisolates were genetically diverse andMRSPof other lineages thanST71 continues to disseminate in Norway. Susceptibility testing showed thatMRSPisolates of theST71 lineage were the most multiresistant. Our study showed thatMRSPcould be detected in healthy dogs without infections and with no recent history of antimicrobial therapy stressing the need for future monitoring, infection control and prudent use of antimicrobial agents.