Mycobacterium marinum

Background

• Bacteria that causes "fish tank Granuloma"
• Can infect both immunocompetent and immunocompromised hosts

Risk Factors

• Aquarium workers and enthusiasts
• Swimming
• Handling of contaminated water

Clinical Features

Fish tank granuloma.

Fish tank granuloma spreading via lymphatic channels.

• Solitary to multiple superficial red nodules or plaques in exposed areas
  • Lesions on the hands and fingers if works with aquariums, or the knees and elbows in swimmers

Diagnosis

Diagnosis is clinical aided by histopathology. Lesions are red nodules/plaques. May progress to abscess or deep-space infections. May also disseminate (rare).

Management

1. Long-term antibiotic therapy
   • Monotherapy with doxycycline, clarithromycin, bactrim, or minocycline (1, 2).
   • Secondary to drug high levels of drug resistance, may require dual drug therapy
2. Warm compresses may also help as the bacterium is heat-sensitive.

References

• Petrini, B; "Mycobacterium Marinum: ubiquitous Agent of Waterborne Granulomatous Skin Infections." European Journal of Clinical Microbiology and Infectious Diseases. October 2006, Volume 25, Issue 10, pp 609-613
• Rallis, E; Koumantaki-Mathioudaki, E; "Treatment of Mycobacterium Marinum Cutaneous Infections." Expert Opinion on Pharmacotherapy. Volume 8, Issue 17, 2007
• Ryan, J and Bryant G. "Fish tank granuloma - a frequently misdiagnosed infection of the upper limb." J Accid Emerg Med. 1997 Nov; 14(6): 398–400.