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

Abstract

Mupirocin is used as a topical antibiotic against staphylococci, including methicillin-resistant Staphylococcus pseudintermedius (MRSP). The recent emergence of resistance to mupirocin is a major concern in many countries. This study investigated the prevalence and genotype of mupirocin-resistant Staphylococcus pseudintermedius isolated from pet dogs with pyoderma. 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 visiting the Veterinary Medical Teaching Hospital of Seoul National University. Low- and high-level mupirocin resistance were evaluated with the broth microdilution and disk diffusion tests. Mupirocin resistant S. pseudintermedius was confirmed by genetic analysis of the ileS-2 and naïve ileS gene. MRSP and methicillin-susceptible S. pseudintermedius were detected in 69 and 41 dogs, respectively. One MRSP strain was resistant to mupirocin and contained the high-level mupirocin resistance gene ileS-2. There were no low-level mupirocin-resistant isolates. Mupirocin is a useful topical antibiotic for S. pseudintermdius, but clinical MRSP isolate that have not been previously 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.