Bacterial colonization and infection of electrophysiological cardiac devices detected with sonication and swab culture

Circulation. 2010 Apr 20;121(15):1691-7. doi: 10.1161/CIRCULATIONAHA.109.906461. Epub 2010 Apr 5.


Background: Electrophysiological cardiac devices are increasingly used. The frequency of subclinical infection is unknown. We investigated all explanted devices using sonication, a method for detection of microbial biofilms on foreign bodies.

Methods and results: Consecutive patients in whom cardiac pacemakers and implantable cardioverter/defibrillators were removed at our institution between October 2007 and December 2008 were prospectively included. Devices (generator and/or leads) were aseptically removed and sonicated, and the resulting sonication fluid was cultured. In parallel, conventional swabs of the generator pouch were performed. A total of 121 removed devices (68 pacemakers, 53 implantable cardioverter/defibrillators) were included. The reasons for removal were insufficient battery charge (n=102), device upgrading (n=9), device dysfunction (n=4), or infection (n=6). In 115 episodes (95%) without clinical evidence of infection, 44 (38%) grew bacteria in sonication fluid, including Propionibacterium acnes (n=27), coagulase-negative staphylococci (n=11), Gram-positive anaerobe cocci (n=3), Gram-positive anaerobe rods (n=1), Gram-negative rods (n=1), and mixed bacteria (n=1). In 21 of 44 sonication-positive episodes, bacterial counts were significant (>or=10 colony-forming units/mL of sonication fluid). In 26 sterilized controls, sonication cultures remained negative in 25 cases (96%). In 112 cases without clinical infection, conventional swab cultures were performed: 30 cultures (27%) were positive, and 18 (60%) were concordant with sonication fluid cultures. Six devices and leads were removed because of infection, growing Staphylococcus aureus, Streptococcus mitis, and coagulase-negative staphylococci in 6 sonication fluid cultures and 4 conventional swab cultures.

Conclusions: Bacteria can colonize cardiac electrophysiological devices without clinical signs of infection.

MeSH terms

  • Adult
  • Aged
  • Aged, 80 and over
  • Biofilms*
  • Defibrillators, Implantable / adverse effects
  • Defibrillators, Implantable / microbiology*
  • Female
  • Follow-Up Studies
  • Gram-Negative Bacteria / isolation & purification
  • Gram-Negative Bacterial Infections / diagnosis
  • Gram-Negative Bacterial Infections / microbiology
  • Gram-Positive Bacteria / isolation & purification
  • Gram-Positive Bacterial Infections / diagnosis
  • Gram-Positive Bacterial Infections / microbiology
  • Humans
  • Male
  • Microbiological Techniques
  • Middle Aged
  • Pacemaker, Artificial / adverse effects
  • Pacemaker, Artificial / microbiology*
  • Prospective Studies
  • Prosthesis-Related Infections / diagnosis*
  • Prosthesis-Related Infections / microbiology*
  • Sonication