Non-tuberculous Mycobacterial pulmonary disease due to novel mycobacterium: Mycobacterium habikinoensis: a case report.

BACKGROUND: The incidence of non-tuberculous mycobacterial pulmonary disease (NTM-PD) is increasing, and the identification of new Mycobacterium species is also increasing. We describe the first case of chronic pulmonary infection caused by a novel Mycobacterium species. CASE PRESENTATION: A 66-year-old man was referred to our hospital with a several-week history of low-grade fever and productive cough. An acid-fast bacillus smear test of the sputum revealed positive. Polymerase chain reaction (PCR) for Mycobacterium intracellulare was positive; however, Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) failed to identify the strain. The isolated culture was referred for further genotypic identification and was confirmed to be a novel species. Combination therapy with clarithromycin, rifampicin, and sitafloxacin was started. Despite treatment, the patient’s condition gradually worsened during the subsequent follow-up period. CONCLUSIONS: We describe the first case of NTM-PD with a novel Mycobacterium species. Mycobacterium habikinoensis is a novel species closely related to Mycobacterium colombiense but with distinct characteristics. Further investigation is required to clarify its pathogenicity, antimicrobial susceptibility, and clinical significance in human infections.