What could be the reason why mycobacterium tuberculosis is resistant to many biocides?

It's complicated: Tb needs to be treated with several drugs to which it is susceptable at the same time to prevent the emergence of mutational resistance. It also needs to be treated for at least 6 months. In many 3rd world countries TB meds can be purchased over the counter and people take them incorrectly and not long enough. In usa some pts are non compliant with treatment. Both these cause resistance.

AntibioticResistance: Resistance is caused by non compliance as people do not take two or three drugs for six months or more.It in the long term make some antibiotics ineffective due to bacterial resistance.But another factor is the Bacteria become smart and as the Antibiotics are used over the years find a different mode to survive like all other Antibiotcs we have used over the years.It is a big problem