Molecular detection of major coagulase-positive Staphylococcus isolates from the canine otitis externa

Abstract

Canine otitis externa (COE) represents one of the most frequently diagnosed inflammatory diseases in dogs, with coagulase-positive staphylococci (CoPS) serving as major etiological agents. This study investigated the prevalence and molecular characterization of CoPS isolated from different breeds of dogs presenting with clinical otitis externa. A total of 87 ear swabs were collected, yielding 53 Staphylococcus isolates after primary staining. Of these, 47 (88.7%) tested positive for coagulase production using the tube coagulase test. All coagulase-positive isolates were confirmed as belonging to the genus Staphylococcus by 16S rRNA gene-targeted PCR. Species-level identification was performed using species-specific thermonuclease (nuc) gene PCR assays targeting S. pseudintermedius (Pse-nuc), S. aureus (Au-nuc) and S. schleiferi subsp. coagulans (Sch-nuc). S. pseudintermedius was the predominant species (67.92%, 36/53 isolates), followed by S. aureus (15.09%, 8/53), S. schleiferi subsp. coagulans (5.66%, 3/53) and coagulase-negative or unidentified Staphylococcus spp. (11.3%, 6/53). These results underscore the dominance of S. pseudintermedius among coagulase-positive staphylococci associated with COE.