4th Annual WML Academic Symposium

There are an estimated 10.1 million commercial hogs in NC and 9.4 million people. Hogs, sometimes treated with fluoroquinolones (FQ), generate vast amounts of fecal waste every year. Waste can be sprayed on farms; however, this results in environmental and public health concerns because of the potential exposure to antibiotic resistant bacteria. Humans may come in contact with these resistant organisms through ingestion of contaminated food which may transfer resistance to human commensal bacteria. FQ are second-line antibiotics used to treat infections in humans. FQ resistance, gained through plasmids, may be transferred to other species of bacteria. The purpose of this research is to evaluate the prevalence of FQ resistance and to characterize the genetic mechanism of the resistance in Gram negative bacteria from hog fecal samples prior to and after treatment with Enrofloxacin. These samples were cultured with and without selective pressure. Both pre and post treatment colony counts showed no significant difference in the number of resistant bacteria, suggesting low acquisition of resistance after a single treatment. PCR was used to screen resistant Gram negative bacteria for the presence of common plasmid mediated FQ resistance genes including: qnrA, qnrB, qnrS, and aac-(6’)-lb-cr. Out of 27 Gram negative resistant colonies, 7 showed positive results for aac-(6’)-lb-cr gene, two for qnrA, and one for qnrB. Positive PCR products will be purified and sequenced to confirm the presumed resistance genes. Other possible mechanisms of FQ resistance for cultured Gram positive and Gram negative bacteria will be explored.