Atypical mycobacterial disease - including symptoms, treatment and prevention
Mycobacteria can be categorised into three broad groupings:
- Mycobacterium tuberculosis complex which causes tuberculosis (TB)
- M. leprae which causes leprosy (Hansen’s disease)
- atypical mycobacteria (also called non-tuberculous mycobacteria).
Atypical mycobacteria are common in the environment and can be found in water (including tap water), soil, food, and on animals. Occasionally atypical mycobacteria cause disease in humans. Examples of atypical mycobacteria include:
- M. abscessus
- M. marinum
- M. avium-intracellulare complex (MAC).
Most atypical mycobacteria are found worldwide, however, M. ulcerans which causes Buruli ulcer (also called Daintree or Bairnsdale ulcer) occurs mostly in tropical regions with pockets in other areas such as the Mornington and Bellarine Peninsulas in Victoria.
All mycobacterial infections, including atypical mycobacterial infections are a notifiable conditions1
How atypical mycobacterial disease is spread
The method of spread of atypical mycobacteria is uncertain but it is likely spread is through:
- contamination of broken skin such as cuts or insect bites
- injection of contaminated fluids
- contamination of surgical wounds, medical equipment or implants
- ingestion of contaminated food or drink
- breathing in tiny particles containing the infectious organisms.
Signs and symptoms
There are four main symptom types:
Pulmonary (lung) disease
Symptoms may include:
- shortness of breath
- blood-stained sputum (phlegm)
- weight loss
- chest pain.
Disseminated (widespread) disease
Symptoms may include:
- general unwellness
- decreased appetite
- weight loss
Disseminated disease is more common in people on immunosuppressing medications or with severe immune deficiencies such as advanced human immunodeficiency virus (HIV) infection.
Lymph node swelling
Lymph node swelling, usually in the neck, which is painless and without other symptoms.
Skin and soft tissue infection
Skin and soft tissue infection with ulcers (for example, Buruli ulcer) or nodules, which can progress to involve tendons or bone.
Diagnosis is confirmed by laboratory testing (culture or PCR) on clinical specimens such as bone marrow, sputum, abscess fluid, or ulcer biopsy. Several specimens may be needed to confirm the diagnosis as detection can be difficult. Laboratory results need to be interpreted with care and in conjunction with clinical findings as colonisation2 or specimen contamination may occur.
(time between becoming infected and developing symptoms)
The incubation period depends on the species of atypical mycobacteria. It ranges from a few days to several months.
(time during which an infected person can infect others)
Unknown. Person to person spread is rare.
Seek expert advice. Treatment in hospital may be needed.
Antibiotic treatment may or not be needed and courses may be complex; in some cases several antibiotics may be needed for up to 2 years.
Surgical removal of the infected area may be needed.
- Exclusion from childcare, preschool, school and work is not usually necessary
- use appropriate infection control procedures during surgical procedures and piercings
- do not inject non-sterile or unapproved substances such as those used in alternative therapies.
1 – In South Australia the law requires doctors and laboratories to report some infections or diseases to SA Health. These infections or diseases are commonly referred to as 'notifiable conditions'.
2 - When bacteria are living on or in the human body, but are not causing infection, it is called ‘colonisation’.