Sonication of explanted cardiac rhythm management devices for the diagnosis of pocket infections and asymptomatic bacterial colonization.
BACKGROUND
Correct diagnosis of the causative organism is critical for the treatment of pacemaker and defibrillator pocket infections. No gold standard for this exists, although swab and tissue cultures are frequently used. The purpose of this study was to determine the value of ultrasonication of explanted generators in the diagnosis of pocket infections and asymptomatic bacterial colonization.


METHODS
Samples were prospectively collected during pacemaker and defibrillator generator extractions for elective replacements, upgrades, or pocket infections. The devices were placed in an ultrasonicator for 5 minutes and the fluid sent for culture, along with swab and tissue cultures.


RESULTS
Eighty-two patients with pacemakers (n = 46) or defibrillators (n = 36) underwent generator explantation, 66 of these for elective reasons and 16 for pocket infection. In patients with pocket infection, 15 (94%) received a definitive bacterial diagnosis using a combination of all three-culture modalities. Cultures were positive in 15 sonicated fluid, 13 tissue, and 11 swab samples, with Staphylococcus aureus and other skin flora commonly seen. In asymptomatic patients, 14 (21%) had positive cultures. Cultures were positive in 11 sonicated fluid, eight tissue, and two swab samples. Skin flora was commonly seen, but three of the sonicated fluid cultures grew gram-negative rods. No patients with asymptomatic colonization developed clinical infection during the follow-up period.


CONCLUSIONS
Ultrasonication is an inexpensive and simple technique that improves the bacteriologic diagnosis of device pocket infections. It also identifies a significant proportion of patients with asymptomatic colonization, although this is not a marker of future pocket infection.
Mason
Pamela K
PK
University of Virginia Health System, Charlottesville, Virginia, USA. Pkm5f@virginia.edu
Dimarco
John P
JP
Ferguson
John D
JD
Mahapatra
Srijoy
S
Mangrum
J Michael
JM
Bilchick
Kenneth C
KC
Moorman
J Randall
JR
Lake
Douglas E
DE
Bergin
James D
JD
D000368:Aged; D015373:Bacterial Typing Techniques / Q000379:methods*; D017147:Defibrillators, Implantable / Q000382:microbiology*; D005260:Female; D006801:Humans; D008297:Male; D009205:Myocarditis / Q000175:diagnosis / Q000382:microbiology*; D010138:Pacemaker, Artificial / Q000382:microbiology*; D016459:Prosthesis-Related Infections / Q000175:diagnosis / Q000382:microbiology*; D013010:Sonication / Q000379:methods*; D013048:Specimen Handling / Q000379:methods