[Can a combination of 2 antibiotics prevent the emergence of resistant mutants?]

The risk of selecting a resistant mutant during the course of treatment is one of the reasons advanced for prescription of a combination of two antibiotics with different mechanisms of action. The aim of combining antibiotics is to render unlikely the selection of a double mutant from a numerous bacterial population. The best example illustrating the validity of this therapeutic approach is that of tuberculosis. Certain combinations give favorable clinical results which would be in agreement with evidence of synergism in vitro. Such combinations are prescribed only under special conditions in infections due to multiple resistant bacterial strains. In many circumstances it must be recognized that no good bacterial and epidemiological arguments exist on which to base the choice of the combination and the ways in which it might be administered.