An increase in antibiotic-resistant tuberculosis bacteria is proving to be a problem in treating this disease. this could be due to

Answer;

-Evolution

Explanation;

Drug-resistant TB remains a significant challenge in TB treatment and control programmes worldwide. Drug resistance in M. tuberculosis is caused by the acquisition of mutations in genes that code for drug targets or drug-activating enzymes. The evolution of strains resistant to multiple antibiotics is driven by the sequential acquisition and accumulation of resistance-conferring mutations on the bacterial chromosome.

Drug resistance occurs due to;  primary or transmitted drug resistance, which occurs when resistant strains are transmitted to a new host, and the secondary or acquired drug resistance, which occurs through the acquisition of drug resistance mutations to one or more drugs.

Natural selection

Explanation:

Darwin and Wallace talked about the natural selection that is the selection done by nature. An interesting example comes from the antibiotic resistance or drug resistance. We continuously use several drugs and antibiotics against the disease causing microbes. With course of time, it may happen that some of the microbes develop resistance against these drugs by bringing changes or modifications in their structures. Those which become resistant , they survive and hence get selected by the nature. Hence, developing drug resistance by microbes is also an example of natural selection. Due to this there is continuous need of new antibiotic development which are active against the microbes,

when it is at an intermediate population density