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)

• Nontuberculous Mycobacterial Lung Disease Across Asia

  Nontuberculous mycobacteria (NTM) are environmental organisms found in soil, dust and water. Unlike Mycobacterium tuberculosis, they are not usually spread from person to person. Yet several species can colonise or infect the airways, producing chronic cough, fatigue, weight loss, breathlessness and recurrent chest infections.

  Across Asia, the epidemiology of NTM pulmonary disease is becoming clearer, although the available picture remains uneven. Countries differ in laboratory capacity, reporting systems, access to computed tomography and the clinical thresholds used to distinguish contamination, colonisation and active disease.

  The most frequently identified organisms include the Mycobacterium avium complex (MAC), M. abscessus and M. kansasii. Disease is especially relevant among older adults, people with bronchiectasis or chronic obstructive pulmonary disease, and those receiving immune-modifying medicines.

  For Australian respiratory clinicians, Asian trends matter because of regional travel, migration, shared research networks and similar environmental exposures. The APSR and KATRD clinical communities provide an important setting for comparing surveillance methods, diagnostic standards and treatment outcomes across the Indo-Pacific.

  A Regional Picture With Uneven Surveillance

  Reported NTM lung disease has increased in several Asian settings, but the scale of that increase is difficult to measure consistently. Some countries have robust referral-centre data, while others rely on small hospital series. A higher number of diagnoses may reflect genuine growth, improved culture techniques, wider use of CT and greater clinical awareness rather than a single change in transmission.

  Japan, South Korea and Taiwan have contributed substantial data on MAC pulmonary disease. Their ageing populations and high availability of imaging have helped identify patients with nodular-bronchiectatic disease at an earlier stage. In Southeast and South Asia, published evidence is more variable, with underdiagnosis likely where mycobacterial cultures and species-level testing are limited.

  Why NTM Disease Is Increasing

  Population ageing is a major driver. Structural lung disease accumulates with age, while previous tuberculosis, smoking-related disease, air pollution and repeated respiratory infections can leave airways vulnerable. Bronchiectasis is particularly important because damaged, poorly cleared airways allow environmental mycobacteria to persist.

  Urban expansion may add further exposure. Construction dust, indoor crowding and deteriorating water infrastructure can bring people into contact with aerosolised organisms. Heavy rainfall and changing temperatures may also influence environmental reservoirs. These factors do not create a simple causal chain, but they help explain why the burden can vary between coastal cities, industrial regions and rural communities.

  The Species Behind Pulmonary Disease

  MAC is the leading cause of NTM lung disease in many Asian studies. It commonly appears in two clinical patterns: fibrocavitary disease, often associated with older men and pre-existing lung damage, and nodular-bronchiectatic disease, frequently seen in older women without a substantial smoking history. The latter pattern can progress slowly and remain difficult to distinguish from recurrent bacterial infection.

  M. abscessus is clinically important because of its intrinsic resistance and complex treatment pathway. Subspecies identification and assessment of inducible macrolide resistance can affect prognosis and antibiotic selection. M. kansasii is less environmentally widespread than MAC but may produce a tuberculosis-like cavitary illness, making accurate laboratory identification essential in regions where TB remains common.

  Diagnostic Challenges Across Asia

  A positive respiratory culture does not automatically establish disease. International criteria generally require compatible symptoms, radiological abnormalities and microbiological evidence from repeated sputum samples, bronchoscopy or tissue. This distinction is crucial because NTM can contaminate specimens or temporarily inhabit damaged airways without causing progressive infection.

  Access to diagnostics remains unequal. Major hospitals in Seoul, Tokyo, Taipei and Singapore may offer molecular assays, susceptibility testing and specialist review, while remote facilities may need to transport samples over long distances. Australia faces a related challenge in the Northern Territory and other remote areas, where travel, workforce shortages and limited specialist access can delay assessment for Aboriginal and Torres Strait Islander patients.

  Environmental And Social Risk Factors

  NTM occurs naturally in water systems, soil and dust, so exposure is widespread. Aerosols generated by showers, hot-water systems, spas and high-pressure equipment are plausible sources. Household gardening, potting mix and renovation dust may be relevant in Australia, although the precise exposure responsible for an individual infection is rarely possible to prove.

  Climate and geography also shape risk. Brisbane’s humid subtropical conditions, Perth’s dry dust and the wet-season environment of northern Australia create different exposure profiles from those in Melbourne or Sydney. These comparisons should be made carefully: environmental presence alone does not predict disease, and host susceptibility remains central.

  Implications For Australian Practice

  Australia has strong respiratory laboratories and specialist networks, but NTM disease is not managed through a single uniform national notification framework in the way tuberculosis is. Clinicians therefore depend on local surveillance, laboratory databases and clinical registries to understand changing patterns. Private pathology, public hospitals and tertiary bronchiectasis services all contribute to the diagnostic pathway.

  The Australian market also influences care. Access to CT, inhaled therapies, airway-clearance devices and prolonged intravenous or inhaled antibiotics can differ by state, income and distance from a metropolitan centre. A patient in regional Queensland may face very different practical barriers from someone attending a tertiary service in Sydney. Medicare-supported GP assessment and specialist referral remain important entry points, while culturally safe care is essential for Aboriginal and Torres Strait Islander communities.

  Building Better Regional Evidence

  Comparable epidemiology requires shared case definitions, standardised culture methods and consistent species-level reporting. Registries should record symptoms, imaging patterns, previous TB, bronchiectasis, antimicrobial exposure and treatment outcomes. Data should also distinguish incident disease from repeated isolates and identify whether patients receive observation, oral therapy, inhaled treatment or intensive multidrug regimens.

  Digital communication can support this work when evidence is clearly labelled. Patients and clinicians may encounter medical guidance beside unrelated commercial pages, so a search result such as an online cash guide should never be confused with peer-reviewed respiratory information. Conference websites, hospital portals and patient resources should prioritise transparent references, plain language and clear explanations of diagnostic uncertainty.

  The most useful regional research will connect microbiology with clinical outcomes and environmental data. Collaboration between Asian centres and Australian services could clarify why some patients with bronchiectasis develop progressive MAC disease while others remain stable, and could improve access to expert testing outside capital cities.

  NTM lung disease in Asia is a growing and heterogeneous respiratory health issue shaped by ageing, bronchiectasis, environmental exposure, diagnostic capacity and healthcare access. For Australia, the key lesson is that reliable species identification, culturally safe pathways and consistent surveillance are as important as new treatments. What readers should remember is simple: an NTM isolate is a clinical clue, not a diagnosis by itself, and its meaning depends on the patient, the imaging and the wider epidemiological setting.

  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)