 [ Symptoms ] how long does it take to find out if you have extensively drug resistant xdr tuberculosis [ Disease ] if tuberculosis bacteria are found in the sputum phlegm the diagnosis of tb can be made in a day or two but this finding will not be able to distinguish between drug susceptible regular tb and drug resistant tb to determine drug susceptibility the bacteria need to be grown and tested in a laboratory final diagnosis for tb and especially for extensively drug resistant tuberculosis xdr may take from six to 16 weeks