A patient of tuberculosis was put on ATT for 5 months. Sputum examination is positive for AFB. The likely cause is -

<p> Treatment failed - a TB patient whose sputum smear or culture is positive at month 5 or later during treatment. Relapse patient have previously been treated for TB,were declared cured or treatment completed at the end of their most recent course of treatment, and are now diagnosed with a recurrent episode of TB. Drug resistance means resistance to anti-TB drugs. Park&;s textbook of preventive and social medicine,K.Park,23rd edition,page no:180. <\p>