Emergence of fluoroquinolone resistance in Mycobacterium tuberculosis during continuously dosed moxifloxacin monotherapy in a mouse model.

Fluoroquinolone resistance in tuberculosis may rapidly emerge. Mice infected with high titers of aerosolized Mycobacterium tuberculosis and treated for 8 weeks with four concentrations of moxifloxacin (0.125, 0.25, 0.50, and 1.0%) mixed into the diet had drug concentrations of 2.4, 4.1, 5.3, and 17.9 microg/ml, respectively, in blood. Selection of fluoroquinolone-resistant mutants occurred in all surviving mice.