Bacterial colonization and infection of electrophysiological cardiac devices detected with sonication and swab culture.
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.
Rohacek
Martin
M
Department of Internal Medicine, Luzerner Kantonsspital, Luzern. martin.rohacek@gmail.com
Weisser
Maja
M
Kobza
Richard
R
Schoenenberger
Andreas W
AW
Pfyffer
Gaby E
GE
Frei
Reno
R
Erne
Paul
P
Trampuz
Andrej
A
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