Frequency of permanent pacemaker or implantable cardioverter-defibrillator infection in patients with gram-negative bacteremia

Background. Despite the frequent occurrence of bacteremia due to gram-negative organisms in patients with underlying permanent pacemakers ( PPMs) or implantable cardioverter defibrillators ( ICDs), the outcome and treatment of these patients has received scant attention. In patients with PPMs or ICDs who have Staphylococcus aureus bacteremia, 45% have PPM/ICD infection. Methods. We conducted a retrospective cohort study over a 7-year period to assess the clinical features and frequency of PPM/ICD infection in patients with gram-negative bacteremia, as well as the incidence of relapse in patients for whom the device was not removed. Results. Forty-nine patients were included in the study; 3 ( 6%) had either definite ( 2 patients) or possible ( 1 patient) PPM/ICD infection. Both patients with definite PPM/ICD infection had clear infection of the generator pocket. None of the other patients with alternate sources of bacteremia developed PPM/ICD infection. Thirty-four patients with retained PPM/ICD were observed for 112 weeks ( median time, 759 days), and 2 ( 6%) developed relapsing bacteremia, although they each had alternative sources of relapse. Conclusions. In sharp contrast to S. aureus infection, PPM/ICD infection in patients with gram-negative bacteremia was rare, and no patients appeared to have secondary PPM/ICD infection due to hematogenous seeding of the system. Despite infrequent system removal in these patients, relapsing bacteremia among patients who survived initial bacteremia was rarely seen. If secondary PPM/ICD infection occurs in patients with gram-negative bacteremia, it is either uncommon or it is cured with antimicrobial therapy despite device retention.