Ciprofloxacin has been used to treat C. jejuni in humans, but due to the increased use of fluoroquinolone in poultry, it is contributing to fluoroquinolone-resistant strains of C. jejuni to arise. Since 1995, the fluoroquinolones sarafloxacin and enrofloxacin were licensed to control death in chickens that were infected with E. coli. The use of these antibiotics is not very well controlled, medication of poultry is to treat the entire house through the water. Not all birds may be ill, but they are still ingesting these antibiotics. This is a cause for concern because these resistant strains can be transferred to humans via consumption of contaminated poultry, thus creating human C. jejuni that is less responsive to fluoroquinolone therapy. A single point mutation in the gyrA gene is responsible for high-level ciprofloxacin MICs in C. jejuni. Cross resistance between different agents in the fluoroquinolone class is expected due to its power to inhibit DNA gyrase.
The FDA’s guidelines for antibiotic use in poultry is to stop treatment two days before slaughter for enrofloxacin, but this withdrawal time is not adequate to reduce the number of resistant Campylobacter species. These resistant strains can still be recovered after three weeks in chickens. If these poultry carcasses that were treated with enrofloxacin become contaminated during processing, fluoroquinolone-resistant C. jejune strains can be present.