Changes in antimicrobial sensitivity of fecal E. coli in pigs exposed to enrofloxacin by different dosing routes: evidence for the “Mutant Selection Window”

The fluoroquinolones (FQ) are synthetic, broad spectrum bactericidal antibiotics which use in Canada is restricted to companion animals and beef cattle. Since their introduction in veterinary medicine, FQ-resistant bacteria are emerging in domestic animals, but the relationship between drug use and drug resistance awaits elucidation. Recently, the “mutant selection window” (MSW) concept has been proposed to explain the enrichment of resistant bacteria during FQ exposure [1]. Because drug eff