Once an individual is diagnosed with active TB disease, treatment is started immediately. He/She will be placed on medical leave during the initial period of treatment, until he/she is no longer infectious.
Exposure to TB would have been in the period before active TB disease was diagnosed and treatment started for the patient.
As there is no further risk of the TB bacteria spreading to other people in the workplace, there is no need to close the workplace, as long as the patient with active TB disease adheres to Directly Observed Therapy (DOT) treatment regularly.