Mycobacterium fortuitum complex A31.9

Author: Prof. Dr. med. Peter Altmeyer

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Last updated on: 25.02.2023

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Atypical mycobacterioses, Mycobacterium fortuitum complex; Mycobacterium fortuitum-chelonae complex; Mycobacterium fortuitum complex; Mycobacterium fortuitum complex - infections

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Skin infections caused by pathogens of the Mycobacterium fortuitum complex.

The Mycobacterium fortuitum complex (MFC) consists of several closely related, fast-growing species of nontuberculous mycobacteria (NTM). The pathogens can cause pulmonary and extrapulmonary infections in humans worldwide. Representatives of this group are:

  • M. abscessus
  • M. fortuitum
  • M. chelonae.

Pathogens of the Mycobacterium fortuitum complex are among the common non-tuberculous mycobacteria (NTM) that do not cause tuberculosis or leprosy disease in humans, along with the pathogens of the Mycobacterium avium-intracellulare complex and Mycobacterium marinum (Sander MA et al. 2018). Pathogens of the Mycobacterium fortuitum complex play an important role in immunocompromised individuals, in whom they can cause skin, soft tissue, and systemic manifestations.

Infection with the pathogens occurs after minor trauma, but also after medical procedures (injections, indwelling cannulas, liposuction, tattoos, acupuncture, and others (Gracia-Cazaña T et al. 2017). Mycobacterium fortuitum infections have also been observed after face-lift surgery (Chazan B et al. 2018).

Systemic infections are also possible via contaminated tap water, as versch. NTMs are capable of biofilm formation in water pipes (García-Coca M et al. 2019).

Clinical features
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Cutaneous infection with Mycobacterium fortuitum often results in, localized, livid-red painful plaques and/or ulcerated or crusted nodules (Franco-Paredes C et al. 2018).

In immunosuppressed patients, it can lead to disseminated infections with lymphadenitis (Hernández-Solís A et al. 2019), osteomyelitis, pneumonia, and sepsis.

In a larger collective of non-immunosuppressed patients with pneumonia, M. fortuitum, among other non-tuberculous mycobacteria (atpic mycobacteria), played a significant role.

The following species were detectable:

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Material to be examined can be obtained from the wound or an abscess, depending on the type of infestation. The pathogens are detected by Ziehl-Neelsen staining, PCR (antigen detection) and culture (Löwenstein-Jensen agar). The pathogens belong to the fast-growing mycobacteria and are culturally detectable after only 3-7 days.

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Depending on the species, different therapeutic approaches are possible. Due to strong antibiotic resistance (Shen Y et al. 2018), macrolides such as clarithromycin or azithromycin are used, combining them with ethambutol, for example.

Fluoroquinolones such as ciprofloxacin may also be used.

Double antibiotics are often used (e.g. clarithromycin +doxycycline or cotrimoxazole).

Note: In any case, resistance testing of existing isolates should be performed (Shen Y et al. 2018).

Operative therapie
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It is not uncommon (due to the resistance situation) for surgical treatment to be the only way to cure infections with pathogens of the Mycobacterium fortuitum complex.

Case report(s)
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A complex skin infection with Mycobacterium fortuitum is described in a previously healthy adolescent girl.

In the present case, Mycobacterium fortuitum caused superficial, crusty plaques and nodules, partly in sporotrichoid arrangement, which appeared about 4 weeks after a (banal) trauma of the skin of the lower leg. A biopsy was performed in which suppurative and necrotising granulomas with giant cells were detected. A culture was made from the biopsy material with detection of M. fortuitum.

Ther: Because of the size and number of lesions, surgical therapy was rejected in favour of chemotherapy. The standard chemotherapeutic approach for M. fortuitum infections involves the use of a combination of at least two antimicrobial agents to which the isolate is sensitive. Despite in vitro sensitivity tests indicating that the patient's isolate was resistant to most antimicrobial agents, the patient was successfully treated with an oral trimethoprim-sulfamethoxazole/azithromycin combination (therapy duration 3 months).

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  1. Chazan B et al (2018) Post-facelift infection due to Mycobacterium fortuitum: A case report. Isr Med Assoc J 20:524-525.
  2. Franco-Paredes C et al (2018) Cutaneous Mycobacterial Infections. Clin Microbiol Rev 32. pii: e00069-18. doi: 10.1128/CMR.00069-18.
  3. Gharbi R et al. (2019) Nontuberculous mycobacteria isolated from specimens of pulmonary tuberculosis suspects, Northern Tunisia: 2002-2016. BMC Infect Dis 19:819 .
  4. Gracia-Cazaña T et al (2017) Mycobacterium fortuitum infection after acupuncture treatment. Dermatol Online J 23(9). pii: 13030/qt0572r5qp.
  5. García-Coca M et al. (2019) Inhibition of Mycobacterium abscessus, M. chelonae, and M. fortuitum biofilms by Methylobacterium sp.J Antibiot (Tokyo) doi: 10.1038/s41429-019-0232-6 .
  6. Griffith DE et al (2007) Am J Respir Crit Care Med 175: 367-416.

  7. Hernández-Solís A et al.(2019) Nontuberculous mycobacteria in cervical lymphadenopathies of HIV-positive and HIV-negative adults. Rev Med Inst Mex Seguro Soc 56:456-461.

  8. Sander MA et al (2018) Cutaneous Nontuberculous Mycobacterial Infections in Alberta, Canada: An Epidemiologic Study and Review. J Cutan Med Surg 22:479-483.
  9. Shen Y et al (2018) In Vitro Susceptibility of Mycobacterium abscessus and Mycobacterium fortuitum Isolates to 30 Antibiotics. Biomed Res Int:4902941.


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Last updated on: 25.02.2023