Increased incidence of cutaneous nontuberculous mycobacterial infection, 1980 to 2009: a population-based study

Objectives: To determine the incidence and clinical characteristics of cutaneous nontuberculous mycobacterial (NTM) infection during the past 30 years and whether the predominant species have changed.

Patients and methods: Using Rochester Epidemiology Project data, we identified Olmsted County, Minnesota, residents with cutaneous NTM infections between January 1, 1980, and December 31, 2009, examining the incidence of infection, patient demographic and clinical features, the mycobacterium species, and therapy.

Results: Forty patients (median age, 47 years; 58% female [23 of 40]) had positive NTM cultures plus 1 or more clinical signs. The overall age- and sex-adjusted incidence of cutaneous NTM infection was 1.3 per 100,000 person-years (95% CI, 0.9-1.7 per 100,000 person-years). The incidence increased with age at diagnosis (P=.003) and was higher in 2000 to 2009 (2.0 per 100,000 person-years; 95% CI, 1.3-2.8 per 100,000 person-years) than in 1980 to 1999 (0.7 per 100,000 person-years; 95% CI, 0.3-1.1 per 100,000 person-years) (P=.002). The distal extremities were the most common sites of infection (27 of 39 patients [69%]). No patient had human immunodeficiency virus infection, but 23% (9 of 39) were immunosuppressed. Of the identifiable causes, traumatic injuries were the most frequent (22 of 29 patients [76%]). The most common species were Mycobacterium marinum (17 of 38 patients [45%]) and Mycobacterium chelonae/Mycobacterium abscessus (12 of 38 patients [32%]). In the past decade (2000-2009), 15 of 24 species (63%) were rapidly growing mycobacteria compared with only 4 of 14 species (29%) earlier (1980-1999) (P=.04).

Conclusion: The incidence of cutaneous NTM infection increased nearly 3-fold during the study period. Rapidly growing mycobacteria were predominant during the past decade.