PERFORMANCE OF ACCESSORY GENE REGULATOR IN VIRULENCE EXPRESSION AND BIOFILM FORMATION OF METHICILLIN-RESISTANT STAPHYLOCOCCUS PSEUDINTERMEDIUS

Staphylococcus pseudintermedius-induced soft tissue infection is a typical biofilm-related infectious disease. Recently, the occurrence of methicillin-resistant S. pseudintermedius (MRSP) infections in humans has increased. In this study, the virulence of different accessory gene regulator (agr) types of MRSP and MRSP[Formula: see text]induced skin infection were investigated through in vitro studies and the murine pyoderma model, respectively. Forty-seven canine clinical MRSP isolates were collected from northern Taiwan and classified into four agr types, namely, type I (52%), type II (2%), type III (35%), and type IV (10%). The majority of the MRSP isolates belonged to either strong (49%) or moderate (42.5%) biofilm producers. The skin damages induced by type III 77, type III 79, and type IV n10 isolates were larger than those induced by type I 58 and type II n3 isolates, but not by a significant degree. The effects of cell adhesion, cell invasion and cell cytotoxicity tests for agr type III 77, type III 79, and type IV n10 isolates were stronger than those caused by other types of MRSP isolates. However, the biofilm formation ability of these MRSP isolates did not show association with their virulence differences for causing murine skin abscesses. The agr type III 77, type III 79, and type IV n10 isolates of MRSP from the clinical samples revealed increased bacterial virulence for causing pyoderma, which is worthy of further genomic studies.