Hospital officials in Denver say a third test on a man quarantined with a dangerous strain of tuberculosis has come back negative for the presence of TB bacteria.

Doctors say the tests mean Andrew Speaker is considered to have a relatively low chance of spreading the disease. It opens up the possibility that he could be briefly allowed out of isolation.

Normally, TB patients with three negative sputum tests who have undergone two weeks of treatment are allowed to leave their isolation room for short periods as long as they wear a mask.

A hospital spokesman says no decision has been made yet on when Speaker will be able to leave his room.

Doctors are hopeful Speaker's tuberculosis can be cured because it is not widespread and because he is otherwise healthy and young.