# Comorbidity profiles of non-tuberculous mycobacteria infections in China: 12 years’ experience

## TL;DR

NTM infections in Beijing are rising, linked to comorbidities like malnutrition and lung disease, with distinct patterns by species and gender.

## Contribution

Identifies species-specific and gender-specific comorbidity profiles for NTM infections in China over 12 years.

## Key findings

- NTM infections are strongly associated with malnutrition, bronchiectasis, and liver disease.
- M. intracellulare is more linked to diabetes and malnutrition compared to M. abscessus.
- NTM cases show stronger ties to lung damage and immunosuppression than tuberculosis.

## Abstract

Nontuberculous mycobacteria (NTM) are of increasing public health concern. This study aimed to determine the most relevant comorbidities of NTM in Beijing, China, over a 12-year period. A retrospective analysis was performed on all 505 NTM patients diagnosed in Beijing Chest Hospital, Capital Medical University, from January 2010 to December 2021. Species identification, demographic characteristics, and comorbidities were analyzed using electronic medical records. The demographic characteristics and clinical comorbidity differences between NTM and tuberculosis (TB) patients were also analyzed. The number of patients infected with NTM in Beijing, China, has increased yearly. A total of 520 NTM were isolated from 505 inpatients, but only 465 were identified to the species level. M. intracellulare (43.44%, 202/465) and M. abscessus (128/465, 27.52%) predominated. NTM infection was associated with age, not gender. NTM infections were predominantly middle-aged (median 59 years, IQR 48.5–67) with a male-to-female ratio of 1:11. Notably, 86.1% of NTM disease had underlying conditions, most commonly malnutrition (43.0%), liver disease (31.1%), and bronchiectasis (25.0%), followed by previous TB (118/505, 23.37%), diabetes mellitus (63/505, 12.48%), hypertension (58/505, 11.49%), and pulmonary fungal infections (54/505, 10.69%). Gender-specific associations emerged: bronchiectasis was more prevalent in females (33.05% vs 17.67%, P < 0.001), while chronic obstructive pulmonary disease (COPD) predominated in males (9.77% vs 2.93%, P=0.002). Species-specific comorbidity patterns were identified: M. intracellulare was associated with malnutrition (50.50% vs 33.59%, P < 0.001) and diabetes (14.83% vs 4.69%, P < 0.001). Compared to TB, NTM cases showed stronger associations with structural lung diseases and immunosuppression. Clinical NTM infection cases increase year by year, with distinct species-specific comorbidity profiles. Our findings reveal that NTM disease is strongly associated with specific comorbidities, notably bronchiectasis, COPD, and immunological diseases. These conditions define a high-risk patient subgroup that requires targeted screening and proactive clinical management.

This study reveals a concerning rise in non-tuberculous mycobacteria (NTM) infections in Beijing, with M. intracellulare and M. abscessus as dominant species. Nearly 90% of patients had comorbidities like malnutrition, bronchiectasis, and liver disease, showing NTM's strong ties to weakened health. The work uncovers key differences from tuberculosis, including greater associations with lung damage and immunosuppression, plus gender-specific patterns (e.g., bronchiectasis in women). These findings highlight NTM as a growing threat requiring tailored diagnostic and treatment approaches, especially for vulnerable groups. The data provide crucial guidance for clinicians addressing this emerging challenge.