SAN DIEGO – Bone and joint infections caused by Staphylococcus lugdunensis are an underestimated hospital-acquired infection often associated with orthopedic devices, according to a multicenter study.
“Consider potential relapse even after 1 year of the end of antibiotic treatment and follow patients with bone and joint infections caused by S. lugdunensis for a minimum 2 years after the end of treatment,” lead study author Dr. Piseth Seng said in an interview at the annual Interscience Conference on Antimicrobial Agents and Chemotherapy.
Dr. Piseth Seng
S. lugdunensis is a virulent coagulase-negative staphylococcus which behaves like S. aureus. Prior to the current study, only 47 cases are believed to be published in the medical literature, according to Dr. Seng of the department of internal medicine at Assistance Publique des Hôpitaux de Marseille (France). The purpose of the current study was to report a series of 138 cases of S. lugdunensis osteoarticular infection managed in nine hospital centers and three private clinics in France from January 1995 to December 2014.
The mean age of patients was 61 years, and 68% were male. Of the 138 cases, 113 (82%) were associated with an orthopedic device, including 2 cases of infection after anterior cruciate ligament reconstruction, 66 cases of prosthetic joint infection, and 3 cases of vertebral orthopedic device infection. The majority of orthopedic device infections (88%) occurred more than 1 month after implantation, while the remaining 12% occurred within the first month of implantation.
The researchers identified 30 cases (22%) of bone and joint infection that occurred in the absence of an orthopedic device, including 7 cases of arthritis, 21 cases of osteitis, and 2 cases of vertebral osteomyelitis.
The majority of patients (91%) received a combination of antibiotic and surgical treatment, including amputation (6%), orthopedic prosthesis removal (14%), internal orthopedic device removal (23%), and surgical debridement and retention of the orthopedic device (41%). The proportion of S. lugdunensis strains with reduced susceptibility to antistaphylococcal agents was low. Resistant strains included five to oxacillin, four to fosfomycin, two to fusidic acid, two to co-trimoxazole, one to rifampicin, and one to clindamycin.
To date, relapses have occurred in 19% of the 123 patients in whom researchers have complete follow-up data. The readmission rate among these patients was 76%, and four (3%) died of their infection. “These relapses were not associated with risk factor or comorbidity or polymicrobial infection,” noted Dr. Seng, who characterized the incidence of bone and joint infections caused by S. lugdunensis as being under reported. “S. lugdunensis is known as an organism forming biofilms, but treatment options (surgical debridement or prosthesis removal) did not influence clinical outcomes.”
The mean time to relapse was 305 days and no risk factor or comorbidity was associated with relapse.
Dr. Seng acknowledged that the study was limited by its retrospective design. He and his associates reported having no financial disclosures.