Synonym: Frequency of mutation (to give drug-resistance)

Frequency at which detectable mutant cells emerge in a bacterial population in the presence of an antibiotic.

The frequency of mutation measures the number of bacterial cells in a given population with pre-existing mutations allowing those bacteria to survive the hostile conditions e.g., antibiotic exposure. FoR studies show whether drug-resistant mutants can be detected after exposure to an antibiotic but more sophisticated methods of predicting the emergence of mutational resistance to antibiotics are needed e.g. determination of mutation rate.