Mycobacterium paragordonae is an emerging pathogen in human pulmonary disease: clinical features, antimicrobial susceptibility testing and outcomes

Abstract

Objectives: Mycobacterium paragordonae (MPG) is an emerging and less common type of Non-tuberculous mycobacteria (NTM) and we know little about its characteristics and prognosis, hence we constructed this retrospective cohort study.

Methods: MPG was identified using MALD-TOF MS, multi-target combined gene sequencing and WGS. Clinical information was collected, antimicrobial susceptibility testing was measured using the SLOMYCO panel, and optimal growth temperature testing was measured using Lowenstein-Jensen medium.

Results: Eight MPGs were isolated from 1730 NTMs (0.46%); the mean age of MPG pulmonary disease (MPG-PD) patients was 42.38 ± 9.92 years, 37.5% were male, and the average BMI was 18.4 ± 0.51 kg/m². All patients had the symptoms of cough and sputum and CT images mainly presented in patchy or streaky shadows, MPG grew at 25°C, 30°C and 37°C, and the optimal growth temperature is 37°C. MPGs were sensitive to clarithromycin, rifabutin, amikacin, linezolid, moxifloxacin, cotrimoxazole and ciprofloxacin, two isolates were resistant to rifampicin. Two patients had follow up information, their imaging remained stable during the follow-up.

Conclusions: MPG-PD is a rare NTM disease and is more likely to develop in middle-aged, female, and low BMI patients. The patients present with no specific features within the symptoms as well as the CT imaging. The optimal growth temperature of MPG is at 37°C, MPG-PD has excellent sensitivity to drugs recommended by CLSI and presents with a stable disease.

Keywords: Mycobacterium paragordonae; antimicrobial susceptibility testing; clinical features; outcomes; pulmonary disease.

Figure 1.

The identity of suspected Mycobacterium paragordonae clinical isolates by WGS. 1-A: Pairwise comparisons of ANIs of Mycobacterium paragordonae clinical isolates\ Mycobacterium paragordonae 49061 and Mycobacterium gordonae; 1-B: Phylogenetic tree of Mycobacterium gordonae and Mycobacterium paragordonae based on WGS constructed using the neighbor-joining method. MPG: Mycobacterium paragordonae, MG: Mycobacterium gordonae DSM 43247W.

Figure 2.

Growth of Mycobacterium paragordonae at different incubation temperatures.

Figure 3.

(A through E): Short-term follow-up HRCT images of patients with Mycobacterium paragordonae pulmonary disease; (A): HRCT images at the initial diagnosis in case 6; (B) HRCT images after the end of anti-tuberculosis treatment in case 6; (C) HRCT images 2 years after cessation of treatment in case 6; (D, E) HRCT images at the initial diagnosis and after 9 months of follow-up in case 8, respectively.