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 T-B 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, T-B 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.

Doctors are hopeful Speaker's tuberculosis can be cured because it is not widespread, he is otherwise healthy and young, and his hospital has extensive experience in removing stubborn, drug-resistant infections.

"He has a number of features that make us optimistic about the potential outcome of his treatment," said Dr. Michael Iseman, senior staff physician at National Jewish Medical and Research Center.

Speaker, 31, of Atlanta, was found to have multidrug-resistant TB, which can withstand two mainline drugs used to treat tuberculosis. While he was in Europe on his honeymoon last month, tests revealed he had extensive drug-resistant tuberculosis, or XDR-TB, which can withstand more drugs.

Speaker's TB was caught early by chance in January when he had a chest X-ray for a rib injury. Otherwise, Speaker has not shown any other symptoms of the disease — coughing, loss of weight or a fever.

Speaker's strain has so far resisted at least 10 of 14 drugs available for treating TB, according to tests performed in Georgia, Iseman said. Surgery to remove infected lung tissue about the size of a tennis ball is one option. The infection's relatively small size increases the chances of success of any surgery.

Surgery to eradicate TB is one of National Jewish's specialties, noted Dr. Neil Schluger, a professor of medicine at Columbia University Medical Center.

"In particular, they've had more experience operating on patients with drug-resistant TB than just about any other hospital in the United States," Schluger said.

A study of 205 patients treated for multidrug resistant TB at National Jewish between 1983 and 1998 showed that those who underwent surgery had a 90 percent cure rate, Iseman said. About 20 of those patients are believed to fall into the newly created XDR category, and doctors are trying to find cure and survival rates for those patients, he said.

Of all 205 patients, 9 percent died of TB, Iseman said.