Medical students at risk of nosocomial transmission of Mycobacterium tuberculosis

SETTING: University and teaching hospital in Rio de Janeiro, Brazil, a city with a high prevalence of tuberculosis (TB). OBJECTIVE: To determine whether medical students are at increased risk of n osocomial transmission of Mycobacterium tuberculosis relative to other univ ersity students. DESIGN: A cross-sectional study of medical and chemical engineering student s in different levels of their training programmes. Information about socio -demographic characteristics, BCG vaccination history, and potential exposu res to TB were obtained using a standardised questionnaire. Tuberculin skin testing (TST) was used to determine the prevalence of infection with TB. RESULTS: Medical students have an increasing prevalence of TST positivity a s they advance in their training programme to increasing levels of study (4 .6%, 7.8%, 16.2%, respectively, P < 0.001), but chemical engineering studen ts do not (4.2%, 4.3%, 4.4%, respectively, P = 0.913). The risks are greate st during the years of clinical training, when medical students have increa sed contact with patients. CONCLUSIONS: Medical students in this setting may be at increased risk of M . tuberculosis infection, relative to chemical engineering students. A prog ramme of routine tuberculin skin testing is needed, combined with intervent ions to reduce the risk of nosocomial transmission in the workplace.