Iatrogenic outbreak of M. chelonae skin abscesses

We describe an outbreak of skin lesions due to Mycobacterium chelonae subsp. abscessus associated with injections of lidocaine (lignocaine) given by a 'bioenergetic' (a practitioner of alternative medicine) in Colombia. The lidocaine carpules and the lesions of the patients yielded mycobacteria with identical biochemical characteristics. Using the methodology of Sartwell and a case control design we examined the incubation period and assessed risk factors. Of 667 potentially exposed individuals, a total of 298 patients were interviewed, of whom 232 had skin lesions. The median incubation period was 30.5 days (range 15-59 days). Male sex (OR 2.85, 95% CI 1.26-6.51), increasing age (OR 1.25, 95% CI 1.03-1.53), subcutaneous injection route (OR 3.72, 95% CI 1.09-12.7) and number of injections (OR 1.01, 95% CI 1.00-1.03) were risk factors for disease. To our knowledge, this is the largest reported outbreak of M. chelonae infection, the first in which the organism has been isolated from the putative vehicle of infection, and the first in which the incubation period could be determined.