Topic I/11) Atypical mycobacterial infections

Question 1

Atypical mycobacteria

Answer 1

M. marinum
M. ulcerans
M.fortuitum complex (MFC)

Question 2

Mycobacterium marinum infection („fish tank granuloma”)

Answer 2

inflammatory, verrucous or crusted lesion(s) at the site of inoculation of the bacteria, which is usually on the dominant hand. Extension to lymphatics (sporotrichoid spread) and deeper tissues may occur.

Treatment
self limited, Clarithromycin with either Rifampin or Ethambutol for 3-4 months.

Question 3

Mycobacterium ulcerans

Answer 3

gigantic, deep, painless ulcerations
Mycolactone, a secreted polyketide toxin is responsible for the tissue damage (necrosis) which originates in the subcutaneous fat
Treatment:
Application of heat to the lesion is effective since
M.ulcerans prefers cooler temperatures.
Surgical debridement and skin grafting is also effective, but antimycobacterial drug therapy is not

Question 4

Mycobacterium fortuitum complex (MFC) infection:

Answer 4

M.fortuitum, M.abscessus and M.chelonae
lesions appear as dark red, infiltrated nodules, with or without abscess formation. Drainage of serous exudate may also be present.
treatment:
Ciprofloxacin.
Surgical debridement with delayed closure is effective for localized infections.