Mycobacterium smegmatis Infection in a Cardiovascular Implantable Electronic Device in an Immunocompetent Patient

Cardiovascular implantable electronic devices (CIEDs) are increasingly utilized for arrhythmia management, but device-related infections remain a significant complication. Rapidly growing non-tuberculous mycobacteria (RGM), including Mycobacterium smegmatis, are rare causes of CIED infections, typically reported in immunocompromised patients or in association with indwelling catheters. These infections pose diagnostic and therapeutic challenges due to non-specific clinical presentations and intrinsic antimicrobial resistance. We report an immunocompetent elderly patient who developed complete heart block requiring pacemaker implantation. The patient subsequently experienced device-related complications, including lead dislodgement and multiple revisions, followed by development of a pacemaker pocket site infection. Blood cultures grew M. smegmatis, and imaging revealed a significant fluid collection at the pocket site. The patient was managed with complete device removal, placement of a leadless pacemaker, and targeted multidrug antimicrobial therapy guided by susceptibility testing. The patient responded favorably, with resolution of bacteremia and pocket site infection. This case highlights the importance of considering M. smegmatis as a potential pathogen in CIED infections, even in immunocompetent hosts. Successful management requires prompt recognition, source control through device removal, accurate microbiologic diagnosis, and prolonged, susceptibility-guided antimicrobial therapy. Clinicians should maintain a high index of suspicion for RGM infections in patients with indwelling device infections, particularly when initial empiric therapy fails. Although rare, M. smegmatis CIED infections can occur in immunocompetent patients and are associated with device manipulation or revisions. This report underscores the need for vigilance, multidisciplinary management, and prolonged follow-up in such complex infections.