Presence of quinolone resistance in swine enteric flora

Commercial hog farms utilize antibiotics in their livestock for three main uses: prophylaxis, growth promotion, or therapeutics. Recurrent sub-therapeutic doses of antibiotics can promote antibiotic resistance, which may lead to overgrowth of resistant enteric flora. Fluoroquinolone antibiotics (FQ) are second-line antibiotics that should only be used when an infection cannot be cleared up using first-line antibiotics. FQ use in livestock has already been banned in several countries due to the potential risk of zoonosis caused by FQ resistant bacteria. However, in the United States, fluoroquinolones are utilized for prescription only treatment in commercial farming. We seek to determine if Gram negative bacteria resistant to FQ can be cultured from the fecal material of hogs previously treated with intravenous antibiotics at label dosing. Fecal samples were collected from hogs treated with enrofloxacin, and bacteria were cultured from the feces of swine both pre- and post-treatment with FQs. PCR screening will determine if samples contain common FQ resistance genes. DNA sequencing of the quinolone resistance-determining region (QRDR) of the gyrA gene in FQ-resistant strains will identify evolved resistance to FQ treatment. This research is important because it investigates the potential for the development of antibiotic resistance stemming from the use of antibiotics in livestock.