Staphylococcus pseudintermedius (S. pseudintermedius) is a primary causative agent of canine topical skin and ear infections and systemic infections. There is an increasing prevalence of methicillin-resistant S. pseudintermedius, with many cases demon...
Staphylococcus pseudintermedius (S. pseudintermedius) is a primary causative agent of canine topical skin and ear infections and systemic infections. There is an increasing prevalence of methicillin-resistant S. pseudintermedius, with many cases demonstrating multidrug resistance (MDR). For this reason, the importance of accurate and rapid detection of methicillin resistance has increased for appropriate treatment.
The major mechanism of this resistance is the production of penicillin binding protein 2a (PBP2a), encoded by the mecA gene. PBP2a possesses transpeptidase activity similar to intrinsic PBPs, but structural differences result in a low affinity for β-lactams.
Typically, disk diffusion and minimum inhibitory concentration (MIC) tests using cefoxitin or oxacillin are utilized to detect methicillin resistance in Staphylococci. Also, mecA polymerase chain reaction (PCR) or commercial assays designed to target PBP2a have been used.
This study aimed to evaluate the PBP2a latex agglutination test (PBP2a LAT) originally designed for S. aureus and Coagulase-negative Staphylococci (CoNS), as an alternative approach to detect methicillin resistance in S. pseudintermedius.
S. pseudintermedius isolates (n=100) collected from dogs diagnosed as pyoderma were evaluated. When accepting mecA PCR results as the gold standard of methicillin resistance, 69 isolates were methicillin-resistant, and 31 isolates were methicillin-susceptible. The PBP2a LAT exhibited a sensitivity of 100% (69/69) (95% confidence interval [CI], 94.8 to 100%) and specificity of 96.8% (30/31) (95% CI, 83.3 to 99.9%), which were same to those of oxacillin disk diffusion method.
In conclusion, the utilization of the latex agglutination assay targeting PBP2a in canine S. pseudintermedius isolates could be a cost-efficient and time-saving method, serving as a sole test to confirm methicillin resistance.
Keywords: Canine, mecA gene, methicillin resistance, penicillin binding protein 2a, Staphylococcus pseudintermedius
Student Number: 2022-22993