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A multicenter evaluation of tuberculin skin test positivity and conversion among health care workers in Brazilian hospitals


SETTING: Four general Brazilian hospitals.

OBJECTIVE: To assess the occupational risk of Mycobacterium tuberculosis (TB) in participating hospitals.

DESIGN: In phase one of this longitudinal study, a cross-sectional survey documented baseline tuberculin skin test (TST) positivity rates. In phase two, TST conversion rates were evaluated in participants with an initial negative two-step TST. TST conversion data were analyzed to determine risk factors for TB infection using an increase of > or = 10 mm compared to baseline TST.

RESULTS: The initial TST positivity rate was 63.1%; the follow-up TST conversion rate was 10.7 per 1000 person-months (p-m). Hospital of employment, recent bacille Calmette-Guerin (BCG) vaccination, nosocomial TB exposure, and employment as a nurse were independent risk factors for TST conversion. Hospitals without TB infection control measures had higher conversion rates than those with control measures (16.0 vs. 7.8/ 1000 p-m, P < 0.001).

CONCLUSIONS: This study indicates an important occupational risk of infection in health care settings with a high TB incidence. Longitudinal TST studies are a valuable tool to assess the occupational risk of TB, even in BCG-vaccinated populations, and should be used to direct limited resources for infection control.

Roth VR, Garrett DO, Laserson KF, Starling CE, Kritski AL, Medeiros EA, Binkin N, Jarvis WR

Int. J. Tuberc. Lung Dis. 2005 Dec;9(12):1335-42

PMID: 16466055