Staphylococcus epidermidis small colony variants, clinically significant quiescent threats for patients with prosthetic joint infection

Abstract

ObjectivesStaphylococcus epidermidis is a leading cause of prosthetic joint infection. Its relevance is based on its high ability to develop biofilm and small colony variants. However, the clinical associations between this bacterial subpopulation and prosthetic joint infections remain highly uncertain. We aimed to define the clinical characteristics and outcome of patients affected by S. epidermidis small colony variants, as well as their antimicrobial susceptibility. MethodsWe conducted a retrospective cohort study of patients with monomicrobial prosthetic joint infection. Clinical data and time to remission after prosthesis removal was compared between groups. Antimicrobial susceptibility of small colony variants and wild type strains were analyzed. ResultsS. epidermidis small colony variants were identified in 16 (37.20%) cultures from eligible subjects. These patients were less likely to achieve remission throughout the follow-up period (Hazard ratio, 0.45 [95% CI, 0.22-0.89], p=0.02), compared to those with wild type strains. In vitro experiments showed higher resistant rates to trimethoprim/sulfamethoxazole (62.5%), and lower resistant rates to levofloxacin (37.5%), among small colony variants. ConclusionsThe isolation of small colony variants was negatively associated with remission achievement throughout management. The search for this bacterial subpopulation and its antimicrobial susceptibility may be appropriate to adjust treatment and clinical expectations.