Staphylococcus simulans as an authentic pathogenic agent of osteoarticular infections

Objectives To evaluate the role of Staphylococcus simulans in bone and joint infections (BJI) and determine their main characteristics. Methods A search of the database of the microbiology laboratories of Lille hospital and Tourcoing hospital was performed. Only results from blood, bone, and orthopedic device cultures were taken into account for hospitalized patients between January 2004 and January 2009. We considered cases in which S. simulans was the only bacteria isolated in all of the patients' biological samples with clinical and laboratory signs of infection. For patients with complete medical records, we recorded the clinical and epidemiological data. Results Six cases of BJI due to S. simulans were recorded, with five cases related to orthopedic devices infections. Three patients lived in rural areas. In four out of six patients, S. simulans was isolated in intraoperative biopsy material. In one patient, S. simulans grew in synovial fluid and in another in blood cultures only. The latter patient had a spondylodiscitis, and chronic foot ulcers due to gout disease were suspected to be the origin of the infection. All patients were healed after a mean follow up of 9 +/- 3 months. Orthopedic devices were removed in four of the five patients concerned. The combination of rifampicin plus levofloxacin was used in four patients. Conclusion The present data suggest that, even though S. simulans remains rarely observed in clinical pathology, its role in osteoarticular infections, especially in the case of infected orthopedic devices, is not exceptional. As for the antibiotic treatment, the combination of rifampicin and levofloxacin seems to be an effective strategy according to our clinical results.