Rapid growers include:
(1) M. abscessus
(2) M. chelonae
(3) M. fortuitum
Lesions may include:
(1) chronic ulcers
(2) localized abscesses
(3) multiple skin lesions
Risk factors:
(1) older age
(2) immunosuppressive therapy, including organ transplantation
(3) multiple comorbid conditions (diabetes, malignant tumor, end-stage renal disease, congestive heart failure, connective tissue disease)
(4) history of surgery, trauma or subcutaneous injection
(5) history of skin abrasion in a hot tub
When to suspect that an infection may be caused by a rapid grower:
(1) chronic ulcer or subcutaneous abscess
(2) negative bacteria and fungal cultures
(3) failure to respond to standard therapy
(4) presence of one or more risk factors (above)
(5) absence of alternative diagnoses that can explain the lesion
The key to diagnosis is considering the possibility of an atypical mycobacterial infection, followed by appropriate biopsy and culture.
