Briefly explain in an evolutionary context and in a biochemi

Briefly explain in an evolutionary context and in a biochemical context how Mycobacterium tuberculosis resistance to the antibiotic rifampicin may arise.

Solution

Rifampin resistance occurs because of missense mutations in the rifampin resistance-determining region, an 81-base pair region encoding the rifampin binding site on the subunit of RNA polymerase (rpoB). These mutations have a survival advantage in the presence of rifampin.

fitness costs associated with resistance mutations is that it implies that in mixed bacterial populations and in the absence of sufficient antibiotic selective pressure. They have advantage of survival in the the presence of rifampsin and they outcompete and replace the non resistance gene completely. So these population will be evolutionary more fit and causing antibiotic resistance.