Clinical characteristics, susceptibility profiles and treatment outcomes of pulmonary disease caused by Mycobacterium paraense.

BACKGROUND

Mycobacterium paraense is an emerging slow-growing mycobacterium (SGM) within the M. simiae complex. While reported globally in environmental sources, its clinical significance remains poorly understood, except in Pará State, Brazil, where it frequently causes non-tuberculous mycobacterial pulmonary disease (NTM-PD).

METHODS

We retrospectively studied 13 patients meeting ATS/ERS/ESCMID/IDSA criteria for M. paraense NTM-PD (2000-2018). Identification was confirmed by sequencing 16S rRNA, hsp65, and rpoB genes. Antimicrobial susceptibility testing (AST) used broth microdilution. Treatment outcomes followed the 2018 NTM-NET consensus.

RESULTS

M. paraense accounted for 8.9% of NTM-PD cases at our center. Median age was 59 years; 92.3% had underlying bronchiectasis. History of tuberculosis (TB) treatment was common (76.9%), with a median diagnostic lag of 26.5 months. Cavitary lesions were significantly associated with smear positivity (p = 0.045). AST showed broad resistance to rifampicin, ethambutol, streptomycin, and ciprofloxacin, but high susceptibility to clarithromycin and amikacin. Patients received empirical macrolide-based regimens (median duration: 18 months); 81.8% of those completing therapy achieved cure (including microbiological cure). No recurrence was observed during follow-up (up to 46 months).

CONCLUSION

M. paraense is a clinically relevant pathogen in the Amazon, frequently misdiagnosed as TB due to cavitary presentation. The high success rate of macrolide-based regimens suggests that strategies for M. avium complex are effective. Enhanced molecular diagnostics are essential to uncover the true global prevalence of this species.