Methods: We retrospectively analyzed cultures in which CS was isolated from 2015 to 2017. We restricted this analysis to patients with orthopedic cultures, bone and PJI. Charts were reviewed for clinical and microbiological data. Duration of follow-up was calculated to the last follow-up visit in our system for the patient after treatment of the infection. “Targeted” treatment was defined as treatment based on antimicrobial susceptibilities of the CS.
Results: We identified 20 cases of OM and 6 PJI with CS identified in culture. 17/26 (65%) were multi-drug resistant. CS was the only organism (monomicrobial) in 46% (12/26) of cultures (8/20 OM, 4/6 PJI). All monomicrobial OM and PJI received targeted treatment and were cured clinically at the last follow-up (average 201 days OM and 124 days PJI). Of 12 polymicrobial OM infections, all improved clinically by last follow-up; 75% (9/12) were treated with targeted treatment for CS and 25% (3/12) without targeted treatment. All polymicrobial PJI (2/2, 100%) improved without targeted treatment.
Conclusion: Our review suggests that CS can cause OM and PJI, with a high rate of drug resistance. Cure rates are excellent in monomicrobial infections when therapy is targeted to susceptibility. The role of targeted therapy for polymicrobial infections in which another more likely pathogen is found is not clear, particularly in the setting of effective surgical source control. Further prospective research is necessary to clarify the prevalence and factors associated with CS infections, and the importance of treatment of this organism in orthopedic infections.