Case Presentation: A man in his thirties with Hb SS sickle cell disease on monthly exchange transfusions presented with one day of pleuritic chest pain and dyspnea. He reported a 15-lb weight loss, night sweats, and poor appetite. He lived in a poorly maintained motel with a slimy showerhead. Vitals showed fever (38.2°C), tachycardia, and hypoxia. Labs revealed leukocytosis with neutrophilia, anemia near baseline, elevated procalcitonin, and reticulocytosis. Imaging showed bilateral opacities, numerous small nodules, and a right middle lobe subsegmental PE. Blood and sputum cultures repeatedly grew Mycobacterium mucogenicum/phocaicum. Initial CAP therapy was changed to imipenem, amikacin, levofloxacin, and linezolid after AFB detection, then narrowed to oral ciprofloxacin and clarithromycin for four weeks after speciation. His port was removed, and he improved clinically with negative follow-up blood cultures.
Discussion: Non-tuberculous mycobacteria (NTM) are acid-fast bacteria found in soil and water (1). NTM are classified into rapidly growing mycobacteria (RGM), which form colonies within seven days, and slow-growing species, which may take several weeks. Clinically, NTM most often cause pulmonary disease; systemic infections occur mainly in immunocompromised hosts, including oncology patients, children with primary immunodeficiencies, and solid organ or hematopoietic stem cell transplant recipients (1). Rapid growers include Mycobacterium fortuitum, M. mucogenicum, M. neoaurum, M. abscessus, M. cosmeticum, M. smegmatis, and M. phlei (2). M. mucogenicum, known for its mucoid colonies, is ubiquitous in water and a recognized cause of nosocomial infections. Central venous catheter (CVC) contamination often results from exposure to tap water during flushing or bathing (3). Catheter-related bloodstream infections (CRBSIs) are common, with ~800,000 cases annually in U.S. ICUs (2). Typical pathogens include coagulase-negative staphylococci, Staphylococcus aureus, Candida species, and enteric gram-negative rods; acid-fast organisms are rare and usually occur in immunocompromised patients with indwelling lines. Among RGM, M. mucogenicum is the most frequent cause of catheter-associated bloodstream infection (2). Patients with sickle cell disease are predisposed to infection due to functional asplenia, impaired phagocytosis, complement dysfunction, and reduced IgG/IgM responses. The mycobacterial cell wall, rich in mycolic acids and peptidoglycan, further protects against complement-mediated lysis and neutrophil killing. Only a few reports describe catheter-related NTM infections in sickle cell disease (4). Clinicians should maintain suspicion for NTM in such patients, as early diagnosis, appropriate antimicrobials, and catheter removal are essential to prevent complications.
Conclusions: Rapidly growing nontuberculous mycobacteria, particularly Mycobacterium mucogenicum/phocaicum, are rare but important causes of catheter-related bloodstream infections. Patients with sickle cell disease are at increased risk due to functional asplenia, immune deficits, and frequent vascular access. Environmental exposure, such as contaminated water, may serve as a source of infection, especially when catheter hygiene is suboptimal. Clinicians should maintain a high index of suspicion for NTM in patients presenting with fever and negative routine cultures, particularly in the setting of an indwelling central line.