Detection of Vancomycin-Resistant Enterococcus faecium Endocarditis After Clearance of Vancomycin-Sensitive Enterococcus faecium Bacteremia.

Vancomycin-resistant enterococcal (VRE) bacteremia is associated with higher mortality rates and longer hospitalizations than vancomycin-sensitive enterococcal (VSE) bacteremia. A 67-year-old man with a right psoas abscess and pacemaker-associated tricuspid valve endocarditis in September 2020 grew VSE from blood cultures that cleared after administration of intravenous vancomycin and gentamicin. Subsequently, he underwent tricuspid valve repair, pacemaker removal, and partial lead extraction. Valve and postoperative blood cultures grew VRE , which cleared after administration of intravenous daptomycin. One VSE and two VRE isolates were collected and sequenced. All isolates belonged to multilocus sequence type ST17 and were closely related, having <20 mutations in pairwise genome comparisons. Vancomycin resistance was due to the acquisition of a plasmid-encoded VanA operon. None of the isolates encoded the virulence factors , , , or ; all encoded a homologue of . VSE , but not VRE isolates, encoded a glucose transporter gene mutation. Two VRE isolates formed more robust biofilms than the VSE isolate ( < 0.001). The VRE isolates, which generated larger biofilms than the VSE isolate, could have remained protected in the heart valve and only caused bacteremia when disrupted during cardiac surgery. This study demonstrates that bacteria detected in the bloodstream of patients with endocarditis may not fully represent the organisms adherent to the cardiac valves or indwelling devices.