Yellow to green phlegm in a tb patient with 4 months myrin treatment. no afb seen in the lab test of this phlegm. what may be it??

Sputum samples are: notoriously inaccurate in diagnosing specific infections, especially TB. Cultures from sputum specimens have a similar problem & take weeks to get a result. While a positive test generally indicates active TB, a negative test may mean only that it was missed. It's important to finish the complete course of treatment. Consider other possible causes of excess phlegm as well. Dr. Anne