LETTER
Skin Ulcers and Tuberculosis Outbreaks
William W. Stead
15 March 1993 | Volume 118 Issue 6 | Page 474
TO THE EDITOR:
Tuberculosis outbreaks after exposure to a patient with an undiagnosed tuberculous skin ulcer [1] and an undiagnosed draining thigh abscess [2] contradict the dictum that extrapulmonary tuberculous lesions are incapable of producing intense exposure reactions in hospital personnel. Aerosolization of Mycobacterium tuberculosis was not caused by tussive expulsion of droplet nuclei but resulted from the great hydrophobicity of tubercle bacilli. This property causes them to concentrate at the surface of aqueous material [3], so that even minor disturbances render them airborne [4]. Wendt and colleagues [5] have shown that M. avium-intracellulare is aerosolized from water by a modest breeze. In our case, and probably in Frampton's case, too, M. tuberculosis was aerosolized during incision and debridement as well as by daily irrigation and dressing change of a large tuberculous abscess. Of the tuberculin-negative staff caring for the patient, 4 of 5 (80%) of the surgical team and 28 of 33 (85%) of the ward staff became infected over a period of 2 weeks [2].
Spread of tuberculosis from open tuberculous lesions may be more frequent in the future because patients with human immunodeficiency virus infection are more likely to develop bacteria-rich extrapulmonary lesions, some of which may afford opportunity for aerosolization of tubercle bacilli.
Frampton's report brings out the utility of preventive therapy and the resistance to re-infection: 11 (19%) of the 59 previously tuberculin-negative personnel became infected, whereas none of the 10 known tuberculin reactors developed disease. Two converters who were not treated with isoniazid developed clinical tuberculosis (100%), whereas none of the 9 who were treated prophylactically did.
1. Frampton MW. An outbreak of tuberculosis among hospital personnel caring for a patient with a skin ulcer. Ann Intern Med. 1992; 117: 312-3.
2. Hutton MD, Stead WW, Cauthen GM, Bloch AB, Ewing WM. Nosocomial transmission of tuberculosis associated with a draining abscess. J Infect Dis. 1990; 161:286-95.
3. Hejkal TW, LaRock PA, Winchester JW. Water-to-air fractionation of bacteria. Appl Environ Microbiol. 1980; 39:335-8.
4. VanOss CJ, Gilman CF, Neumann AW. Phagocytic Engulfment and Cell Adhesiveness. New York: Marcel Dekker; 1975:28-33.
5. Wendt SL, George KL, Parker BC, Gruft H, Falkinham JO III. Epidemiology of infection by nontuberculous mycobacteria. III. Isolation of potentially pathogenic mycobacteria from aerosols. Am Rev Respir Dis. 1980; 122:259-63.
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