Skin and soft tissue infections due to rapidly growing mycobacteria: comparison of clinical features, treatment, and susceptibility.

OBJECTIVE: To compare the demographics, clinical features, susceptibility patterns, and treatment for skin and soft tissue infections due to Mycobacterium fortuitum and Mycobacterium chelonae or Mycobacterium abscessus.

DESIGN: Retrospective medical record review.

SETTING: Mayo Clinic, Rochester, Minn.

PATIENTS: All patients seen at our institution with a positive culture for M chelonae, M abscessus, or M fortuitum from skin or soft tissue sources between January 1, 1987, and October 31, 2004.

MAIN OUTCOME MEASURES: Patient demographics, clinical characteristics, therapeutic data, microbiological data, and outcomes.

RESULTS: The medical records of 63 patients with skin or soft tissue infections due to rapidly growing mycobacteria were reviewed. Patients with M chelonae or M abscessus were older (61.5 vs 45.9 years, P<.001) and more likely to be taking immunosuppressive medications (60% vs 17%, P = .002) than patients with M fortuitum. Mycobacterium fortuitum tended to manifest as a single lesion (89% vs 38%, P<.001), while most M chelonae or M abscessus manifested as multiple lesions (62% vs 11%, P<.001). More patients with M fortuitum had a prior invasive surgical procedure at the infected site (56% vs 27%, P = .04). Patients with multiple lesions were more likely to be taking immunosuppressive medications than those with single lesions (67% vs 30%, P = .006). Seven patients failed treatment, several of whom were immunocompromised and had multiple comorbidities.

CONCLUSIONS: Skin and soft tissue infections due to rapidly growing mycobacteria are associated with systemic comorbidities, including the use of immunosuppressive medications. There are significant differences in the demographic and clinical features of patients who acquire specific organisms, including association with immunosuppression and surgical procedures.