Abstract
Background.
Little is known about the clonality of
Staphylococcus epidermidis
in the United States, although it is the predominant pathogen in infections involving prosthetic materials, including ventricular assist devices (VADs).
Methods.
Seventy-five VAD recipients at 4 geographically diverse US cardiac centers were prospectively followed up to 1 year of VAD support. The anterior nares, sternum, and (future) driveline exit site were cultured for
S. epidermidis
before VAD insertion and at 7 times after surgery. Infection isolates were also collected. Isolates were typed by pulsed-field gel electrophoresis. A subset underwent susceptibility testing and staphylococcal chromosomal cassette
mec
and multilocus sequence typing.
Results.
A total of 1559 cultures yielded 565
S. epidermidis
isolates; 254 of 548 typed isolates (46%) belonged to 1 of 7 clonal types as defined by pulsed-field gel electrophoresis. These clones were identified in up to 27 people distributed across all 4 cardiac centers. They caused 3 of 6 VAD-related infections. Disseminated clones were more antibiotic resistant than were less prevalent isolates (eg, 79% vs 54% methicillin resistant;
P
= .0021).
Conclusions.
This study revealed that healthcare–associated
S. epidermidis
infection is remarkably clonal. We describe
S. epidermidis
clones that are highly resistant to antibiotics distributed across US cardiac centers. These clones may have determinants that enhance transmissibility, persistence, or invasiveness.
Clinical Trials Registration.
NCT01471795.
