C68-30 ICU Puzzle: A Rare Mycobacterial Culprit

Abstract Introduction Mycobacterium immunogenum is a rapidly growing nontuberculous mycobacterium classically associated with metalworking environments. It can cause pneumonitis or predispose individuals to chronic pulmonary infections, although the exact pathogenic mechanism remains unclear. While generally considered low virulence, its coexistence with slower-growing mycobacteria such as Mycobacterium avium complex (MAC) or Mycobacterium chimaera has not been reported. Through this unique case, we aim to raise awareness that pulmonary infections caused by nontuberculous mycobacteria (NTM) often go unrecognized, and when identified, they present significant diagnostic and therapeutic challenges for clinicians. Case Description This is a case of acute on chronic respiratory failure in an 89-year-old male with a history of hyperlipidemia, atrial fibrillation, chronic kidney disease, and recently diagnosed coronary artery disease/STEMI status post cardiac catheterization. He had been experiencing chronic dyspnea and significant sputum production over the past several months. Imaging had shown bilateral nodular and ground glass opacities. Social history was notable for occupational exposure, as the patient had worked in metalworks. Multiple prior sputum cultures had grown Mycobacterium avium and Mycobacterium immunogenum, and antimicrobial therapy was being considered pending susceptibility results while he awaited recovery from STEMI. He was re-admitted to the hospital with acute hypoxic respiratory failure and massive hemoptysis. Repeat imaging studies demonstrated worsening bilateral pleural effusions along with multifocal nodular and ground-glass opacities. He was treated empirically for hospital-acquired pneumonia with broad-spectrum antibiotics. Despite aggressive management, his condition deteriorated, and he ultimately passed away due to multi-organ failure and severe sepsis. Discussion This case highlights the diagnostic and therapeutic challenges of rare NTM pulmonary infections. Diagnosis requires integration of clinical, radiographic, and microbiologic criteria, with exclusion of alternative etiologies. Importantly, meeting diagnostic criteria does not mandate treatment; management should be individualized, considering organism pathogenicity, patient comorbidities, and potential outcome. Mycobacterium immunogenum pulmonary disease is remarkably rare, often diagnosed late, and associated with significant morbidity and mortality. Clinical awareness, prompt diagnosis, and strategies to reduce occupational exposures are crucial to improve outcomes in at-risk populations. This abstract is funded by: None