Literature Review
June 1, 2000 2 minutes read
Literature Review
Franchi A, Amicosante M, Rovatti E, et al. Evaluation of a Western blot test as a potential screening tool for occupational exposure to Mycobacterium tuberculosis in health care workers. J Occup Environ Med 2000; 42:64-68.
Is there a better way to test health care workers for occupational exposure to tuberculosis? Researchers at the University of Modena in Italy say there is: using a Western blot test to detect an antibody as a marker of exposure to TB.
Currently, skin tests measure the reaction to tuberculin purified protein derivative (PPD) to screen health care workers for risk of TB infection. The researchers developed an M. bovis serological Western blot test as an earlier marker of TB contact.
The antibody test could not be used with BCG-vaccinated workers due to their high reactivity. But among non-vaccinated health care workers, the Western blot test did, in fact, detect exposure earlier than the PPD skin test and with greater sensitivity. For example, the Western blot test identified 95% of workers in the tuberculosis and respiratory diseases division as being sensitized to Mycobacterium tuberculosis, as compared to 73% identified by PPD. In the infectious disease division, Western blot identified 59% of workers as sensitized, compared to 41% identified by PPD.
On the downside, the authors noted that the Western blot methodology "would give more limited information about the level or intensity of MTB-exposure than the PPD skin test."
"Overall, this study suggests that the WB test antibody market, as a sensitive indicator of MTB contact among exposed HCWs, might provide, in association with the PPD skin testing, new tools to assess the TB risk in health care facilities with higher accuracy, thus allowing a more timely and appropriate implementation of the environmental and health surveillance measures for the primary prevention and control of TB infection in the workplace," the authors stated.
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