title: Bacterial colonization and infection of electrophysiological cardiac devices detected with sonication and swab culture.
abstract: 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.
  
  
  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.
authors.affiliation: Department of Internal Medicine, Luzerner Kantonsspital, Luzern. martin.rohacek@gmail.com
authors.forename: Martin
authors.initials: M
authors.lastname: Rohacek
authors.forename: Maja
authors.initials: M
authors.lastname: Weisser
authors.forename: Richard
authors.initials: R
authors.lastname: Kobza
authors.forename: Andreas W
authors.initials: AW
authors.lastname: Schoenenberger
authors.forename: Gaby E
authors.initials: GE
authors.lastname: Pfyffer
authors.forename: Reno
authors.initials: R
authors.lastname: Frei
authors.forename: Paul
authors.initials: P
authors.lastname: Erne
authors.forename: Andrej
authors.initials: A
authors.lastname: Trampuz
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D018441:Biofilms; D017147:Defibrillators, Implantable / Q000009:adverse effects / Q000382:microbiology*; D005260:Female; D005500:Follow-Up Studies; D006090:Gram-Negative Bacteria / Q000302:isolation & purification; D016905:Gram-Negative Bacterial Infections / Q000175:diagnosis / Q000382:microbiology; D006094:Gram-Positive Bacteria / Q000302:isolation & purification; D016908:Gram-Positive Bacterial Infections / Q000175:diagnosis / Q000382:microbiology; D006801:Humans; D008297:Male; D008828:Microbiological Techniques; D008875:Middle Aged; D010138:Pacemaker, Artificial / Q000009:adverse effects / Q000382:microbiology*; D011446:Prospective Studies; D016459:Prosthesis-Related Infections / Q000175:diagnosis* / Q000382:microbiology*; D013010:Sonication