K-3422. Ventricular Assist Device Recipients Share Commensal S. epidermidis Clones and are Infected with Colonizing Strains
Session: Poster Session: Device Related Infections
Monday, October 27, 2008: 12:00 AM
Room: Hall C
Background: Infection is a common complication of ventricular assist device (VAD) placement. S. epidermidis (SE) is a frequent cause of VAD infection. Colonization, infection and transmission of SE strains has not been prospectively investigated in VAD patients. Methods: A prospective, observational study of VAD recipients at 11 clinical sites enrolled 150 subjects beginning 1/06. Cultures from the nares, future sternal incision and driveline (DL) exit sites were taken pre-VAD implantation and at set intervals up to 1 yr. Colonies consistent with SE on selective media underwent species confirmation by PCR. Clinical SE isolates were also obtained. Isolates underwent genotyping using PFGE. Strain similarities were analyzed (Bionumerics). We compared commensal and infection isolates in subjects with both and compared all SE isolates at 2 centers. Results: Of 1857 cultures, 22% grew >1 SE isolate. The nares were the most commonly colonized site (35%), followed by the sternum (27%) and future/DL exit site (5.3%). Pre-VAD, 73 (59%) of cultured subjects were colonized with SE. The prevalence dropped to 34% 24-48h after antibiotic prophylaxis was stopped and increased to 51-58% by weeks 2-12. Of 13 subjects with both commensal and clinical isolates, 46% had an identical or closely related isolate in their commensal flora. Commensals were clonal in 11/13 subjects and infection isolates were clonal in all 7 subjects with >1 infection isolate.
At site A there were 7 clusters of identical or closely related (>78% similar) isolates shared among 2-8 patients. At site B, 2-7 subjects were colonized with the same or closely related isolate in 9 instances. Conclusions: SE infections in VAD recipients are clonal and frequently arise from commensal flora. Antibiotic prophylaxis may briefly decrease post-VAD colonization. Sharing of SE strains among VAD recipients at 2 clinical centers demonstrates transmission of strains in the healthcare setting.
Cassie Fairchild1, Franklin Lowy, MD2, Julie Choe1, Mark Slaughter, MD3, Meera Bhat4, Rachel Gordon, MD, MPH5, Ulrike Rawiel1, Yoshifumi Naka, MD1 and  R. Gordon, None., (1)Columbia Univ, (2)Columbia University, New York, NY, (3)Advocate Christ Med Ctr, (4)Columbia University, (5)Columbia U, New York, NY

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