Prevalence of genes encoding for staphylococcal leukocidal toxins among clinical isolates of Staphylococcus aureus from implant orthopedic infections

Staphylococcus aureus has emerged as a major cause of implant infections. It is known that it is able to produce several toxins that contribute to its armory of virulent weapons, but there are still no data on their prevalence among isolates recovered from biomaterial-centered infections. In this study, 200 Staphylococcus aureus isolates from infections related to different types of orthopedic implants (hip and knee arthroprostheses, internal and external fixation devices) were tested by polymerase chain reaction for the prevalence of genes encoding for leukotoxins. Although almost all isolates were positive for the gamma-hemolysin gene (99%), none was positive for lukM. The leukotoxin genes lukE/lukD were found in 67% of isolates. The presence of lukE/lukD was significantly associated with that of Accessory Gene Regulatory locus agr II. The lukE/lukD-positive isolates were significantly more prevalent in the staphylococcal isolates from knee arthroprostheses than in the isolates from the other implant types. The genes encoding Panton-Valentine leukocidin components were detected in only one isolate that, curiously enough, was taken solely from a knee arthroprosthesis infection.