Pulmonary Diseases Caused by Environmental Mycobacteria
Essentials
Consider environmental (also "atypical" or "non-tuberculous") mycobacteria as causative agents in patients with
persistent pulmonary infection and chronic pulmonary disease or immunosuppression
undetermined prolonged pulmonary infections
suspected pulmonary tuberculosis that responds poorly to treatment.
Epidemiology
The incidence of infections caused by environmental mycobacteria is increasing.
The infection is acquired from water or soil, etc.
Human-to-human transmission has not been reported.
Development of a disease often requires an earlier damage to the lungs (e.g. earlier tuberculosis, pulmonary fibrosis, etc.)
Causative agent
The following species cause pulmonary infections: M. avium-intracellulare, M. kansasi, M. xenopi, M. malmoense, M. scrofulaceum, M. simiae, M. szulgai, M. chelonei and M. fortuitum.
Symptoms
Cough
Sputum production
Dyspnoea
Weight loss
Fever and bloody sputum are rare.
Investigations
Bacterial culture
Repeated ample growth of the same species of environmental Mycobacteria in the culture of sputum or bronchial secretion is a significant finding.
Pulmonary disease caused by environmental mycobacteria must be differentiated from mere colonization (or contamination of the specimen).
Radiology
In subacute disease the parenchymal infiltrates and caverns are situated unilaterally in the upper lobe.
In chronic forms the patient often has bilateral fibrotic changes.
Treatment
The treatment is clearly more difficult than the treatment of ordinary tuberculosis.
Treatment options include antituberculous medication, other antimicrobial drugs, and occasionally surgery.
Eradication of the environmental mycobacteria is not always possible.
Treatment is indicated if
there is growth in sputum culture samples repeatedly or in a single sample taken from a location that otherwise is sterile and
chest x-ray shows findings that match with an infection caused by environmental mycobacteria and
the patient has matching symptoms.
If the patient has no or only minimal symptoms, follow-up without medication is in some cases a valid option.
Treatment is started in specialized care.
Notification
Follow the local regulation concerning notification of infectious diseases and reimbursement of treatment.
References
Haworth CS, Banks J, Capstick T ym. British Thoracic Society guidelines for the management of non-tuberculous mycobacterial pulmonary disease (NTM-PD). Thorax 2017;72(Suppl 2):ii1-ii64. [PubMed]