Species and Antimicrobial Susceptibility of Methicillin-Resistant Coagulase-Positive Staphylococcus spp. (MRCPS) isolated from dogs in Thailand

Abstract

The objective of this study was to screen prevalence and antimicrobial susceptibility of Coagulase positive Staphylococcus spp. (CPS) isolated from dogs visiting at the Small Animal Hospital of Chulalongkorn University. Staphylococcus spp. were identified by using of gene detection and PCR-REA technique. In addition, mechanism of methicillin resistance was determined by molecular detection of their resistance genes. 200 samples from both nostril, wound or otitis externa were obtained from 100 dogs. 72 isolates from 200 samples (36%) were found to be Staphyloccoci. Among ofthese , 49 isolates (68.05%) were identified as CPS. The highest prevalence occurrence of CPs found in this study was in nasal cavity, followed by wound and otitis externa, respectively. The PCR technique for molecular detection revealed that S. pseudintermedius was the most common CPS (85.71%) found in dogs. The antimicrobial susceptibility test showed that most of CPS were susceptible to mupirocin (93.88%) whereas few of them were susceptible to cefalexin (2.04%). Moreover, 88% CPS isolates were multidrug resistant (more than 3 drugs) and most of the MDR-CPS resisted more than 4 antimicrobials. The MIC [subscript 50] and MIC[subscript 90]of oxacillin against MDR-CPS were 256 mug/ml. Most of S. pseudintermedius isolates resisted to oxacillin (MIC > 4 mug/ml) whereas no oxacillin resistance of S. aureus and other CPS were found (MIC < 2 mug/ml). No correlation between beta-lactamase screening test and the presence of the resistant gene blaZ and mecA was found in this study. The molecular identification revealed that 22 out of 49 isolates carried both blaZ and mecA gene and their MIC of oxacillin were also higher than those against the isolates carried either blaZ or mecA genes. Most of S. pseudintermedius isolates carried both blaZ and mecA genes. Two out of three S. aureus isolates found in this study carried either blaZ while the other CPS did not carried blaZ or mecA genes. The results from this study showed that the most common of methicillin resistant CPS found in dogs was S. pseudintermedius. These isolates were highly resistant to many antimicrobials, including cefalexin which is commonly used in veterinary practice. Unfortunately, most of them were blaZ and mecA genes carrier. Eventhough, MRSP in people is only a minor concern, the methicillin resistant gene can transmit to the other Staphylococcus spp. including S. aureus that can be the cause of the MRSA spread in the community