Healthcare-associated Exposure to Mycobacterium tuberculosis (MBT)

HCP should obtain a baseline tuberculin skin test (TST), preferably a two-step TST, at the beginning of employment.¹⁶ A positive TST indicates prior exposure to MBT. An exposed person may develop latent TB infection (LTBI). Immunocompetent patients with LTBI have a 10% life-time risk to develop tuberculosis (TB). Those with LTBI are asymptomatic and are non-infectious. Following reexposure, HCP with LTBI require no further testing or PEP.

HCP with a negative TST, in case of unprotected occupational exposure, are susceptible to infection. MBT is transmitted from person-to-person primarily by inhalation of droplets and droplet nuclei generated by talking, coughing, or sneezing. As soon as possible after an exposure to a patient with TB disease, a TST or a blood assay for *Mycobacterium tuberculosis* (BAMT) should be done on HCP known to have had negative results on previous testing.¹⁶

HCP with a previously negative TST or BAMT who subsequently have a positive TST result (a reaction ≥5 mm) or a positive BAMT result should be evaluated for treatment of LTBI. Treatment of LTBI, which should be initiated after the possibility of TB disease has been excluded, greatly reduces the risk of TB disease. The four treatment regimens include isoniazid (6 months), isoniazid (9 months), isoniazid and rifapentine (3 months), or rifampin (4 months).¹⁷