In hospitals where many tuberculosis patients are treated the population of the tuberculosis mycobacteria may be constituted of multiresistant (to antibiotics) strains. How does the synthetic theory of evolution explain this fact?

The appearance of the multiresistant strains of pathogenic parasites in hospitals, for instance, of multiresistant tuberculosis bacteria, can be explained by the synthetic theory of evolution.

Since in any environment, TB bacteria in hospitals undergo changes in their genetic material. In the hospital environment though they suffer continuous exposition to antibiotics many of them die by means of the antibiotic action but carriers of mutations that provide resistance to those antibiotics proliferate freely and these resistant microorganisms when submitted to other antibiotics again undergo natural selection and those which became resistant to these other drugs are preserved and proliferate. Therefore strains of multiresistant (nontreatable) mutant bacteria emerge in hospitals.

The use of antibiotics is a factor that promotes natural selection and the emergence of multiresistant bacteria. This is the reason why hospitals often have committees that control the use of antibiotics.