In vitro antiseptic susceptibilities for Staphylococcus pseudintermedius isolated from canine superficial pyoderma in Japan

Abstract

Topical therapy, particularly with chlorhexidine, is becoming increasingly common as a treatment option for canine pyoderma; however, there are limited studies on the susceptibility of Staphylococcus pseudintermedius to chlorhexidine compounds. To determine the in vitro susceptibility of both meticillin-resistant and meticillin-susceptible S. pseudintermedius isolates to chlorhexidine and other antiseptic agents and the presence of multidrug efflux pump genes. One hundred S. pseudintermedius isolates from 23 initial and 77 recurrent cases of canine pyoderma. After bacterial identification and mecA testing, minimal inhibitory concentrations (MICs) of antiseptic agents were determined. Multidrug efflux pump genes, including qacA, qacB and smr, were identified. Of the 100 isolates, 57 were identified as meticillin-resistant S. pseudintermedius. The MIC(90) of chlorhexidine acetate, chlorhexidine gluconate, acriflavine, ethidium bromide and benzalkonium chloride were 1, 1, 2, 0.5 and 2 μg/mL, respectively. Multidrug efflux pump genes qacA, qacB and smr were not detected in any of the isolates. The MICs for chlorhexidine and other antiseptics remain low, and multidrug efflux pump genes were not found in the tested isolates.