Abstract 14431: Low Prevalence of Bacterial Colonization of Electively Explanted Cardiovascular Implantable Electronic Devices (CIEDs)

Abstract

Background: Whether or not electively explanted CIEDs are colonized with bacterial biofilms is controversial. We evaluated the prevalence of bacterial colonization of electively explanted CIEDs using traditional cultures and culture of material obtained after subjecting the explanted CIED to vortexing-sonication to sample biofilms on its surface.

Methods: We prospectively enrolled 25 subjects undergoing replacement of a CIED generator due to ‘end-of-battery life’ over a period of 4 months. The pulse generator was transported to the laboratory in a sterile jar where Ringer’s lactate was added and vortexing-sonication applied. Sonicate was cultured aerobically and anaerobically in a semiquantitative manner. One device swab, one pocket swab, and one pocket tissue were collected; swabs were cultured aerobically and tissue aerobically and anaerobically.

Results: Eleven of 25 sonicate fluid cultures grew <20 colonies/plate (quantity representative of contamination based on our studies of other implanted foreign body-types), of Propionibacterium sp, coagulase-negative staphylococci (CoNS), Corynebacterium sp, Bacillus sp or Micrococcus sp. Eleven of 25 tissue cultures grew Propionibacterium sp or CoNS, in low quantity (1+ or from broth only). Swab cultures from 3 subjects grew Propionibacterium sp, Corynebacterium sp or Bacillus sp. Discordance between culture positivity or organism isolated was observed in all cases where at least one specimen obtained from the same subject yielded bacterial growth. No subject developed CIED infection in follow-up for up to 6 months from generator replacement.

Conclusion: Our results do not support earlier reports suggesting that asymptomatic latent colonization of CIEDs is common. Bacterial growth observed in cultures using different specimens and techniques was limited to low quantities of low virulence bacteria not consistently isolated using various specimen sources and techniques applied, suggesting that the isolated bacteria most likely represent contaminants. Although the duration of follow-up was limited, no subject developed infection of the newly implanted CIED. These data do not support routinely obtaining cultures at CIED explantation if there is no clinical suspicion of CIED infection.