Sonication of explanted cardiac implants improves microbial detection in cardiac device infections

The sonication technique has been shown to be a promising tool for microbiological diagnosis of device-related infections. We evaluated the usefulness of the sonication method for pathogen detection in 80 explanted cardiac components collected from 40 patients, and the results were compared with those of conventional cultures. Forty subjects undergoing cardiac device removal were studied: 20 had cardiac device infection, and 20 subjects underwent elective generator replacement or revision in the absence of infection. Sonication of explanted devices was more sensitive than traditional culture for microbial detection (67% and 50%, respectively; P = 0.0005). The bacterial count detected in sonication fluid culture was significantly higher than that detected in traditional culture in both infected (P = 0.019) and uninfected (P = 0.029) devices. In the infected patients, sonication fluid culture yielded a significantly higher rate of pathogen detection in explanted electrodes than traditional culture (65% versus 45%; P = 0.02), while no differences were found in the generators. Ten strains were detected only through sonication fluid culture: 6 Staphylococcus epidermidis strains, 1 Staphylococcus hominis strain, 2 Corynebacterium striatum strains, and 1 Brevundimonas sp. Neither the type nor the duration of antimicrobial therapy before device removal had an effect on the diagnostic performance of sonication fluid culture (P = 0.75 and P = 0.56, respectively). In the patients without infection, sonication fluid culture was positive in 8 cases (40%), whereas conventional culture was positive in only 4 (20%). In summary, the sonication technique improves the microbiological diagnosis of explanted cardiac devices.