Factors influencing linezolid-nonsusceptible coagulase-negative staphylococci dissemination among patients in the intensive care unit: a retrospective cohort study.

BACKGROUND The aim of the present study was to identify risk factors for linezolid-nonsusceptible coagulase-negative staphylococci (CNS) dissemination in the intensive care unit. METHODS Among the 246 patients included, 33 revealed a linezolid-nonsusceptible CNS-positive culture specimen, 68 were positive for linezolid-susceptible CNS and 145 served as controls. Isolates were characterized by phenotypic and genotypic methods to species level, susceptibility to antistaphylococcal agents and clones. RESULTS Among the 33 linezolid-nonsusceptible CNS patients, 29 revealed Staphylococcus epidermidis and 4 Staphylococcus capitis. All S. epidermidis strains belonged to the ST22 clone (by multilocus sequence typing), 26 carried both C2534T and T2504A and 3 strains were C2543T mutations. S. capitis strains were stratified as a common pulsed-field gel electrophoresis type and carried the G2576T mutation. Risk factors for linezolid-nonsusceptible CNS isolation were linezolid administration and mean number of linezolid-nonsusceptible CNS-positive patients in nearby beds per day. CONCLUSIONS These results reinforce the aspect of rational antibiotic usage, but also highlight the need for strict infection control measures to prevent the dissemination of linezolid-nonsusceptible CNS.