Thesis (Ph.D.)--Chulalongkorn University, 2012

This study propose the conventional biochemical scheme for species identification of canine coagulase-positive staphylococci (CoPS), S. pseudintermedius, S. schleiferi subsp. coagulans and S. aureus, consisting of acetoin production, assimilation of maltose, galactose, trehalose and lactose in broth base and fermentation of mannitol. The scheme could generate reliable results with genotypic identification and protein pattern analysis. Regarding interspecies transmission, S. pseudintermedius and S. schleiferi subsp. coagulans could be isolated from dog-associated people including veterinarians and dog’s owners but not from people without dog association. With respect to methicillin-resistant trait, MRCoPS could be only recovered from dogs and dog-associated people. The methicillin-resistant S. pseudintermedius (MRSP) was mostly isolated that followed by methicillin-resistant S. schleiferi subsp. coagulans (MRSSc) and methicillin-resistant S. aureus (MRSA), respectively. Using antimicrobial susceptibility test and genetic resistance detection by microarray, over 80% of MRCoPS isolates exhibited multidrug resistance to approved antimicrobials for veterinary use including tetracycline, aminoglycosides, erythromycin, clindamycin, chloramphenicol, trimethoprim, ciprofloxacin and sulfamethoxazole. By multilocus sequence typing (MLST), pulsed-field gel electrophoresis (PFGE) and staphylococcal cassette chromosome (SCCmec) typing, the molecular characteristics revealed that Thai dogs and dog-associated people shared common and various clones of MRCoPS, especially MRSP. These supported the evidence of inter-species transmission of canine MRCoPS between dogs and humans. The standard diagnostic schemes were proposed in this study leading to discovery of multidrug resistance MRCoPS distributing among dogs, veterinarians and dog owners. Thus, to deal with the challenge condition of antimicrobial-resistant bacteria and to diminish the spread to human beings, veterinarians should seriously take action.