Detection of Biofilm-associated Implant Pathogens in Cardiac Device Infections: High Sensitivity of Sonication Fluid Culture Even in the Presence of Antimicrobials

INTRODUCTION: Sonication showed more sensitivity than traditional culture in the diagnosis of device infections. Aims of the study were to assess the role of sonication in the microbiological diagnosis and management of cardiac device infections (CDIs), to evaluate the sensitivity of sonication in patients on antimicrobial therapy at the time of device removal, and to analyze biofilm formation of the isolated strains. MATERIALS AND METHODS: A total of 90 devices (31 generators and 59 electrodes) collected from 31 patients with infection underwent sonication before culture. Devices were sonicated for 5 min and centrifuged at 3200 rpm for 15 min. Intraoperative traditional cultures were performed in 26 patients. Microorganisms were identified using conventional methods. Staphylococcal strains were tested for slime production. RESULTS: Microbiological diagnosis was achieved in 28 patients (90%). Sonicate fluid was positive in 68/90 (76%) of devices (27/31 [87%] generators and 41/59 [69%] electrodes), whereas intraoperative pocket swabs grew bacteria in 10/26 patients (38%, P = 0.0007). Among leads, 37/59 (62.7%) yielded bacteria even in the absence of vegetation. Coagulase-negative Staphylococci accounted for 83.8% (57/68) of the total; Staphylococcus aureus and Gram-negative bacilli were found in 4.4% (3/68) and 5.8% (4/68), respectively. Biofilm production was present in 15/22 (69%) staphylococcal strains. Overall, patients on therapy (n = 23) had a microbiological diagnosis in 20/23 (86.9%) and 7/22 (30.4%) through sonication and intraoperative cultures, respectively (P = 0.0002). DISCUSSION: Our data showed the high sensitivity of sonication in the diagnosis of CDIs, even in patients under antimicrobial therapy. CONCLUSION: Sonication represents an essential tool for both diagnosis and management of CDIs.