Positive cultures in asymptomatic patients during elective device replacement: a murderer hides in the darkness or an innocent person on the crime scene?

Abstract

The paper of Kleeman et al .1 is a prospective observational study on bacterial colonization of implantable cardioverter defibrillator (ICD) systems and its relevance to device infection. Out of 122 patients, without clinical signs of device infection, who underwent ICD replacement or lead revision, 33% had positive cultures. After a median follow-up of 203 days, seven patients developed a device infection (five patients with and two without prior bacterial colonization). The authors conclude that asymptomatic bacterial colonization was a common problem in ICD recipients and became clinically relevant in 7.5% after replacement/revision. This paper presents an interesting and clinically relevant study and addresses the concept of silent colonization of devices or prosthetic valves and the importance of latent infection. Latent infection is a reality. In intravascular-catheter-related infections, colonization of catheters does not induce systemic infection. However, there is a correlation between the number of micro-organisms retrieved by semiquantitative or quantitative cultures from a catheter surface and the risk of associated infection.2 Latent infective endocarditis could be suspected by the presence of an unexpected inflammatory infiltrate in 0.9% of heart valves retrieved for other reasons than endocarditis.3 Several well-done studies found asymptomatic bacterial colonization of pacemaker.4,5 Several hypotheses could explain an equilibrium between the human host and bacteria.6 When … *Corresponding author. Tel: +33 320 445 038, Fax: +33 320 446 898, Email: dklug{at}chru-lille.fr