Low prevalence of mupirocin resistance in Staphylococcus pseudintermedius isolates from canine pyoderma in Korea

Background - Mupirocin is a topical antibacterial drug used for the treatment of staphylococcal infections, including meticillin- resistant Staphylococcus pseudintermedius (MRSP). The recent emergence of resistance to mupirocin is a major concern in many countries. Objectives - This study investigated the prevalence and genotype of mupirocin-resistant S. pseudintermedius isolated from pet dogs with pyoderma. Samples - A total of 110 clinical isolates of S. pseudintermedius were collected from dogs with pyoderma (n = 110) between July 2010 and September 2016. All animals were client-owned dogs. Methods - Low- and high-level mupirocin resistance were evaluated with both the broth microdilution and disk diffusion tests. Mupirocin resistance in S. pseudintermedius isolates was confirmed by genetic analysis of the ileS-2 and naive ileS genes. Results - MRSP and meticillin- susceptible S. pseudintermedius were detected in 69 and 41 dogs, respectively. One MRSP strain was highly resistant to mupirocin and contained the high-level mupirocin resistance gene ileS2. There were no low-level mupirocin-resistant isolates. Conclusion and clinical importance - Mupirocin is a useful topical antibacterial for MRSP, but a clinical MRSP isolate that had not previously been exposed to mupirocin exhibited the high-level mupirocin resistance in phenotype and genotype. Therefore, continuous monitoring for mupirocin resistance is important in small animal practice.