You admit a debilitated patient with pneumonia to the general medical ward. He does not respond well and has a long drawn out hospital course. Weeks later his sputum specimens reveal tuberculosis. Meanwhile several hospital nurses and respiratory therapists have converted their tuberculin skin tests. You're kicking yourself for not having isolated the patient. But how could you have known? You wanted to be a good steward of hospital resources and not utilize isolation rooms unnecessarily. Here's a clinical prediction instrument to help you decide which patients to isolate.