Incubation Alone Is Adequate as a Culturing Technique for Cardiac Rhythm Management Devices

There exist no standardized methods for culturing cardiac rhythm management devices. To identify the most optimal culturing method, we compared various techniques that comprise vortex, sonication, and incubation or combinations thereof. Incubation alone yielded bacterial colony counts similar to those of other culturing combinations and is the least labor-intensive.Permanent pacemakers (PPM) and implantable cardioverter-defibrillators (ICD) are being utilized increasingly because of an aging population (5, 9). About 180,284 PPM and 57,436 ICD were inserted into cardiac patients in the United States in 2003 (10), and worldwide there are 3 million functioning PPM and 180,000 indwelling ICD (2). Infection is the most common serious complication of PPM and ICD, which are collectively referred to as cardiac rhythm management devices (CRMD). The rates of infection of CRMD range from 0.13% to 19.9% (3, 7) with an average rate of 4% (4). Staphylococcus epidermidis and Staphylococcus aureus collectively account for 70 to 95% of CRMD infections (1, 6). A National Hospital Discharge Survey from 1996 to 2003 indicated that along with the rising use of cardiac medical devices, there has been a disproportional increase in the number of infections of such devices (10). The average cost of combined medical-surgical treatment of an infected CRMD was estimated at $35,000 (4).There are no standardized methods for culturing explanted cardiac generators and leads of the CRMD. Although it has been demonstrated that sonication increases the yield of bacterial cultures from prosthetic joints (8), the utility of this diagnostic approach for CRMD has not been published. To identify the most optimal culturing method, we compared the bacterial yield of various techniques that comprise incubation, vortex, sonication and combinations thereof.