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Mycobacterial skin infections

Medical Professionals

Professional Reference articles are designed for health professionals to use. They are written by UK doctors and based on research evidence, UK and European Guidelines. You may find one of our health articles more useful.

It is important to consider mycobacterial infection in any stubborn and atypical skin problem, particularly in immunocompromised individuals.1 Mycobacteria cause slowly developing chronic skin infections.

Mycobacterial infection is increasing, partly due to emerging drug resistance and the HIV epidemic.

Non-tuberculous mycobacteria (NTM) are acid-fast bacteria, widespread in the environment. In children, NTM may cause lymphadenitis, skin and soft tissue infections and occasionally also lung disease and disseminated infections.2 NTM cause infections mainly after trauma, surgery and cosmetic procedures.3

Of the greater than 140 NTM species reported, 25 species have been strongly associated with NTM diseases and the other species are rarely encountered in clinical samples. Correct species identification is very important but the diagnosis is often complex. NTM species vary greatly in their growth rate, temperature tolerance and drug susceptibility.4

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Lupus vulgaris5

  • This is the most common form of cutaneous tuberculosis, occurring after primary infection in individuals with good natural resistance.

  • Females are more often affected and it is also more common in children.

  • Most commonly, it affects the face and neck and is seen initially as firm, translucent, brown nodules.

  • Without treatment, the lesions slowly spread laterally, leading to disfiguring scarring. Malignant change has been reported in these scars.

  • Diagnosis is confirmed by biopsy and culture. Patients should receive full anti-tuberculous therapy for at least one year.


  • Scrofuloderma results from breakdown of skin overlying a tuberculous focus, usually at a lymph node but also at the skin over infected bones or joints.

  • Lesions present as firm, painless, subcutaneous nodules that gradually enlarge and suppurate, then form ulcers and sinus tracts in overlying skin. Typical ulcers have undermined edges and a floor of granulation tissue. It causes fistulae and scarring.

  • Mycobacterium tuberculosis can be identified both in the nodes and in the material draining on to the skin surface.

  • Full anti-tuberculous therapy and surgical excision are required.

Warty tuberculosis7

  • Also known as tuberculosis verrucosa cutis.

  • This is the most common form of cutaneous tuberculosis in developing countries but it is rare in western countries.

  • It occurs with infection in someone who has immunity from previous infection.

  • It causes a warty plaque, often on the hands, knees or buttocks.


  • Skin reactions to systemic tuberculosis - eg, erythema nodosum, erythema induratum (Bazin's disease).

Leprosy (Hansen's disease)8

Leprosy is caused by Mycobacterium leprae and Mycobacterium lepromatosis. Both of these primary affect the skin and peripheral nerves. Contrary to popular belief, it is not highly contagious. Treatment is readily available and early intervention significantly reduces disability. Any damage caused by neuropathy is irreversible and may require lifelong care.

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Environmental mycobacterial diseases

  • Cutaneous infections with atypical mycobacterium are much more common in immunosuppressed patients, especially those with HIV infection, or leukaemia or in those undergoing immunosuppressive therapy.

  • Atypical mycobacterial infections are also more common in the elderly.

  • The environmental mycobacteria cause two named diseases with characteristic features:

    • Fish tank (or swimming pool) granuloma caused by Mycobacterium marinum.

    • Buruli ulcer caused by Mycobacterium ulcerans infection.

  • The other mycobacterioses are much less specific, often resembling tuberculosis.

Buruli ulcer9

  • Buruli ulcer is also known as Bairnsdale ulcer or Searls' ulcer (Australia) and Kakerifu ulcer or Toro ulcer (Congo).

  • It is a re-emerging infection and is now the third most prevalent mycobacterial disease worldwide, behind tuberculosis and leprosy.

  • It is due to infection by M. ulcerans in tropical zones - acquired from vegetation or water after trauma.

  • Initially a painless erythematous nodule develops, usually on the leg or forearm. This eventually becomes necrotic and ulcerates.

  • Treatment is usually by wide surgical excision - antimicrobial therapy with rifampicin and clarithromycin is recommended before and after surgery.

  • Bacillus Calmette-Guérin (BCG) vaccine gives short-term prevention.

Fish tank (or swimming pool) granuloma10

  • This is caused by M. marinum infection, which infects fish and is also found in swimming pools.

  • Typically, it causes a reddish, slightly scaly plaque on the hand or arm of someone who keeps tropical fish.

  • M. marinum is sensitive to minocycline, clarithromycin, amikacin, rifampicin, ethambutol and doxycycline.

Other environmental mycobacteria

  • Mycobacterium kansasii:

    • Most patients who present with localised primary cutaneous M. kansasii infection are immunocompetent, whereas most patients with disseminated or pulmonary infection are immunocompromised.

    • It may resemble cellulitis or sporotrichosis.

    • It may also present with tenosynovitis, cutaneous lymphadenitis; the clinical presentation is similar to that expected in lupus profundus and with ulcerative perineal lesions.

  • Mycobacterium malmoense: cervical lymphadenitis in preschool-aged children. It has also been associated with cutaneous nodules on the hands.

  • Mycobacterium szulgai: cellulitis, nodules and plaques.

  • A case of disseminated Mycobacterium simiae infection with blood, pulmonary and cutaneous localisation has been reported.

  • Mycobacterium gordonae: granulomatous synovitis and bursitis. It is sometimes called tap water scotochromogen. It has also caused granulomatous nodules on the back of the hand.

  • Mycobacterium haemophilum: multiple, tender, cutaneous nodules, which may develop into ulcers or abscesses. They are often situated over limb joints. May lead to muscle wasting, tenosynovitis and joint effusions.

  • Mycobacterium avium complex (MAC): this has emerged as a major human pathogen. Cutaneous disease is caused by direct inoculation (trauma, surgery, injection) and is characterised by skin lesions, such as ulceration, abscess or erythematous plaque.11


  • This mainly affects otherwise healthy children aged under 5 years.

  • It usually affects the cervical lymph nodes, often just a single node.

  • Is caused by many mycobacterial species, most often MAC and Mycobacterium scrofulaceum.

  • Infection in older children and more diffuse involvement are often associated with HIV infection.

  • Surgical excision is curative.

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  • Careful clinical examination is the gold standard.

  • The optimal way to make the diagnosis is by performing a culture of tissue. Most mycobacteria require special culture conditions, which, if not specifically requested, are frequently not used.

  • The development of DNA fingerprinting technology, especially pulsed-field gel electrophoresis, has been suggested as a diagnostic tool.

  • Polymerase chain reaction has been used to aid diagnosis.

  • CXR: associated pulmonary disease.

  • The purified protein derivative test (antigen skin test used to aid the diagnosis of tuberculosis) result is usually negative in infections with atypical mycobacteria.

Mycobacterial skin infection treatment and management13

  • Effective treatment depends on precise diagnosis and identification of the underlying organism. Treatment will also be governed by results of culture and sensitivity.

  • Treatment of atypical mycobacterial skin infections is often difficult because many atypical mycobacteria are resistant to common antibiotics.

  • A combined therapeutic approach, including surgical drainage, debridement and prolonged treatment with combined antimicrobial agents, has been used in some cases of atypical mycobacteria.

  • In some cases (especially fast-growing environmental mycobacteria), successful treatment requires aggressive debridement of all infected subcutaneous tissues and skin.


Scarring and nerve damage can occur from long-standing untreated infections.


The prognosis is good with proper medical and surgical treatment.

However, many patients are often not properly treated because of insufficient health resources in developing countries, or treatment may be difficult because of underlying immunosuppression and consequent diffuse infection.


  • Avoidance of contaminant material.

  • BCG vaccination gives a variable degree and duration of protection.

Further reading and references

  1. Lamb RC, Dawn G; Cutaneous non-tuberculous mycobacterial infections. Int J Dermatol. 2014 Oct;53(10):1197-204. doi: 10.1111/ijd.12528. Epub 2014 Jun 25.
  2. Lopez-Varela E, Garcia-Basteiro AL, Santiago B, et al; Non-tuberculous mycobacteria in children: muddying the waters of tuberculosis diagnosis. Lancet Respir Med. 2015 Mar;3(3):244-56. doi: 10.1016/S2213-2600(15)00062-4. Epub 2015 Mar 9.
  3. Gonzalez-Santiago TM, Drage LA; Nontuberculous Mycobacteria: Skin and Soft Tissue Infections. Dermatol Clin. 2015 Jul;33(3):563-77. doi: 10.1016/j.det.2015.03.017. Epub 2015 May 8.
  4. van Ingen J; Diagnosis of nontuberculous mycobacterial infections. Semin Respir Crit Care Med. 2013 Feb;34(1):103-9. doi: 10.1055/s-0033-1333569. Epub 2013 Mar 4.
  5. Gallo JC, Claasens S, Visser WI, et al; Cutaneous tuberculosis (lupus vulgaris-type). IDCases. 2022 Jan 10;27:e01394. doi: 10.1016/j.idcr.2022.e01394. eCollection 2022.
  6. Mello RB, Vale ECSD, Baeta IGR; Scrofuloderma: a diagnostic challenge. An Bras Dermatol. 2019 Jan-Feb;94(1):102-104. doi: 10.1590/abd1806-4841.20188560.
  7. Jakhar D, Gupta RK, Sarin N; Dermoscopy of Tuberculosis Verrucosa Cutis. Indian Dermatol Online J. 2020 Sep 28;12(1):206-207. doi: 10.4103/idoj.IDOJ_292_19. eCollection 2021 Jan-Feb.
  8. Bhandari J, Awais M, Robbins BA, et al; Leprosy.
  9. Guarner J; Buruli Ulcer: Review of a Neglected Skin Mycobacterial Disease. J Clin Microbiol. 2018 Mar 26;56(4):e01507-17. doi: 10.1128/JCM.01507-17. Print 2018 Apr.
  10. Assiri A, Euvrard S, Kanitakis J; Cutaneous Mycobacterium Marinum Infection (Fish Tank Granuloma) in a Renal Transplant Recipient: Case Report and Literature Review. Cureus. 2019 Oct 28;11(10):e6013. doi: 10.7759/cureus.6013.
  11. Ferreira CP, Coutinho ZF, Lourenco MC, et al; Atypical cutaneous mycobacteriosis caused by Mycobacterium avium complex. Braz J Infect Dis. 2010 May-Jun;14(3):324-6.
  12. Lemus LF, Revelo E; Cervical Tuberculous Lymphadenitis. Cureus. 2022 Nov 9;14(11):e31282. doi: 10.7759/cureus.31282. eCollection 2022 Nov.
  13. Gardini G, Gregori N, Matteelli A, et al; Mycobacterial skin infection. Curr Opin Infect Dis. 2022 Apr 1;35(2):79-87. doi: 10.1097/QCO.0000000000000820.

Article history

The information on this page is written and peer reviewed by qualified clinicians.

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