Bacteriology of infected extracted pacemaker and ICD leads.

Introduction: Pacemaker and implantable cardioverter defibrillator infections, when not treated, lead to serious consequences. The aim is to identify the prevalent strains of the responsible bacteria to guide an effective therapy.

Methods: Between May 2003 and April 2008, 118 leads were extracted from 61 patients, with chronic draining sinus, pocket infection, pacemaker endocarditis, or sepsis. Following extraction, samples of the leads underwent cultural and antibiogram examination.

Results: Staphylococcus epidermidis was the most frequently isolated bacterial strain (37.7%), followed by Gram-positive flora (16.1%), Staphylococcus aureus (14.3%), Candida parapsilosis (5.4%), Staphylococcus schleiferi (5.4%), Corynebacterium species, and Staphylococcus hominis (3.6%). Cultures were negative in 14.3% of the samples. Retained sensitivity to antibiotics were reported as follows: teicoplanin/vancomycin 100%, doxicyclin 96%, amikacin 94%, piperacillin-tazobactam 58%, cotrimoxazole 78%, gentamycin 65%, quinolones 47%, rifampicin 44%, cephalosporins 25%, and oxacillin 25%. Within staphylococci, involved in about 60% of the infections, S. hominis and S. epidermidis showed the highest antibiotic resistance. In case of sepsis, sensitivity was retained for glycopeptides and amikacin (about 100%), and to a lower degree for doxicyclin (80%). Arbitrarily stratifying into recent (<3 months) and chronic (>3 months) infections, an increase in time prior to referral for lead extraction was associated with a significant increase in antibiotic resistance.

Conclusion: Bacteria associated with pacemaker and implantable cardioverter defibrillator-related infections, staphylococci in about 60% of the cases, show poor susceptibility to antibiotics, presenting three out of four methicillin-resistant features. Therefore, systemic antibiotics, mainly glycopeptides, must not be delayed awaiting the complete removal of the implanted system.