Speaker's Highlight

• Don Sin University of British Columbia, St. Paul Hospital (Canada)
  Kenneth R. Chapman Toronto General Hospital Research Institute (Canada)
• Parameswaran Nair McMaster University (Canada)
  Carolyn Calfee UCSF (U.S.A.)
• Gregory P. Downey University of Colorado School of Medicine (U.S.A.)
  David A. Schwartz University of Colorado School of Medicine (U.S.A.)
• Neil Schluger Tuberculosis Control Branch, California Department of Public Health (U.S.A.)
  Nick Kim Critical Care & Sleep Medicine, University of California San Diego (U.S.A.)
• Nicola Hananiah Baylor College of Medicine (U.S.A.)
  Jae-Joon Yim Seoul National University College of Medicine (Republic of Korea)
• Koichiro Asano Tokai University School of Medicine (Japan)
  Diahn-Warng Perng Taipei Veterans General Hospital (Taiwan)
• Konstantinos Kostikas University of Ioannina (Greece)
  Karin Klooster University Medical Center Groningen (Kingdom of the Netherlands)

• The Epidemiology of Nontuberculous Mycobacterial Lung Disease

  Nontuberculous mycobacteria (NTM) are environmental organisms found in soil, dust, natural water and treated water systems. Unlike Mycobacterium tuberculosis, they are not usually spread from person to person. Their importance in respiratory medicine has grown as clinicians identify more cases of chronic cough, bronchiectasis, recurrent infections and unexplained changes on chest imaging.

  The epidemiology of nontuberculous mycobacterial lung disease is complex because exposure is common but clinically significant disease is relatively uncommon. Risk depends on the organism, host health, lung structure, age, immune function and local environmental conditions. In Australia, the large distances between communities, ageing population and uneven access to respiratory specialists make consistent surveillance especially important.

  What NTM Disease Means

  More than 190 NTM species have been described, although a smaller group causes most pulmonary disease. The Mycobacterium avium complex, including M. avium and M. intracellulare, is frequently identified. M. abscessus is clinically important because it can be difficult to treat and may develop resistance during therapy. M. kansasii is less common but often associated with a more tuberculosis-like presentation.

  Finding NTM in sputum does not automatically establish disease. A patient may have temporary contamination or colonisation without tissue damage. Diagnosis generally requires compatible symptoms, radiological abnormalities and repeated microbiological evidence, interpreted according to professional guidelines.

  Who Is Most At Risk

  Structural lung disease is one of the strongest risk factors. Bronchiectasis, chronic obstructive pulmonary disease, previous tuberculosis, silicosis and severe asthma can impair airway clearance and create conditions in which NTM persist. Cystic fibrosis is also associated with selected species, although the management pathway is specialised.

  Age is another important factor, with many patients diagnosed in later adulthood. Low body weight, gastro-oesophageal reflux, immunosuppressive medicines and immune disorders may increase susceptibility. In Australia, clinicians also need to consider prior occupational exposure, smoking history and the effects of chronic respiratory disease in people living far from major hospitals.

  Environmental Reservoirs And Everyday Exposure

  NTM are widespread in the environment, so exposure is difficult to avoid. Aerosols from showers, spa pools and other water sources may carry organisms into the air. Soil and potting mix can be relevant during gardening, particularly when dry material is disturbed. These exposures do not mean that a person has acquired an infection, since ordinary contact is common in the general population.

  Everyday habits may alter exposure levels. In Sydney, Melbourne and Brisbane, people may spend time gardening, using indoor showers with warm water systems or visiting heated pools. Practical precautions, such as avoiding vigorous disturbance of dry potting mix and improving ventilation, can reduce inhalation of dust and aerosols without creating unrealistic restrictions on normal life.

  Patterns Across Australia

  Australia does not have a single, comprehensive national notification system for all NTM pulmonary disease. Published studies often draw on hospital records, laboratory databases or state-based data, which can make comparisons difficult. Differences in testing practices and access to specialist services may create the appearance of regional variation even when the underlying risk is similar.

  Population density, climate, water infrastructure and healthcare access may influence observed patterns. Major centres such as Melbourne, Sydney, Perth and Brisbane have established respiratory services and advanced microbiology laboratories, while remote communities may face delays in sputum collection, imaging, referral and follow-up. Aboriginal and Torres Strait Islander patients can experience additional barriers linked to geography, housing, socioeconomic conditions and access to culturally safe care; surveillance must avoid treating these disparities as biological differences.

  The Burden On Patients And Services

  NTM lung disease often follows a prolonged course. Symptoms may include chronic cough, sputum production, tiredness, breathlessness, chest discomfort and weight loss. Some patients remain stable for years, while others experience progressive bronchiectasis, recurrent exacerbations or declining lung function.

  Treatment can involve several antibiotics for many months after cultures become negative. Side effects may include hearing damage, visual problems, liver injury, gastrointestinal symptoms and drug interactions. The cost is carried by patients, carers and health services through repeated consultations, imaging, pathology, audiology and medication monitoring. Australia’s Pharmaceutical Benefits Scheme supports access to many medicines, but specialist prescribing and monitoring remain essential.

  Improving Diagnosis And Surveillance

  Accurate epidemiology depends on reliable diagnosis. Sputum should be collected on more than one occasion when possible, and laboratories need appropriate culture methods and species identification. A positive result should be reviewed alongside symptoms and high-resolution computed tomography findings, such as nodular disease, cavitation or a tree-in-bud pattern.

  Electronic laboratory reporting could improve understanding of incidence, recurrence and species distribution across Australia. Linking microbiology results with hospital data, bronchiectasis registries and prescribing information would help distinguish new disease from persistent infection. Data governance must protect privacy, particularly in small rural and remote communities where individuals may be identifiable from limited records.

  Practical Priorities For Australian Care

  Management should be individualised rather than based on a positive culture alone. Respiratory physicians, infectious diseases specialists, microbiologists, pharmacists, physiotherapists and primary care clinicians may all contribute. Treatment decisions should consider symptoms, radiological progression, organism susceptibility, drug toxicity and the patient’s goals.

  Useful priorities for services and patients include:

  • Strengthen access to repeated sputum testing and high-quality species identification.
  • Assess bronchiectasis, COPD, previous tuberculosis, immune suppression and other underlying risks.
  • Provide culturally safe referral pathways for Aboriginal and Torres Strait Islander patients.
  • Coordinate antibiotic monitoring through respiratory clinics, community pharmacies and primary care.
  • Discuss hearing, vision, liver function and medication interactions before prolonged treatment.
  • Record cases consistently to support state and national estimates of NTM disease.
  • Give practical advice about gardening, potting mix, shower ventilation and spa exposure without implying that ordinary life must stop.

  The Australian market also requires careful attention to medicine availability. Some NTM regimens involve medicines supplied through different prescribing pathways, and shortages or changing access arrangements can interrupt therapy. The Therapeutic Goods Administration, the Pharmaceutical Benefits Scheme and local antimicrobial stewardship policies all influence how treatment is selected and monitored.

  NTM lung disease reflects the interaction between environmental exposure, vulnerable airways and health-system capacity. Better recognition of bronchiectasis, consistent laboratory methods and stronger data collection can clarify where disease is increasing and which patients need earlier specialist review. For Australian practice, the most useful approach is to pair careful microbiological confirmation with long-term monitoring, practical exposure advice and coordinated care close to where patients live.

  Richard Russell Nuffield Department of Clinical Medicine, University of Oxford (United Kingdom)
• Mona Bafadhel King’s College London (United Kingdom)
  David Jackson Guy’s and St Thomas’ Hospital, King’s College London (United Kingdom)
• James Chalmers University of Dundee (United Kingdom)
  David Price University of Aberdeen (United Kingdom)