Antibiotic resistance in Campylobacter has been deemed by the CDC to be an serious concern. Historically, certain strains of C. coli have been found to be resistant to erythromycin, a macrolide that inhibits protein production and is a drug of choice for treatment of Campylobacter infections, should treatment be indicated. Conversely, C. jejuni strains are much less commonly resistant to erythromycin. However, at the Kathariou lab we have recently found 4 flocks of turkeys colonized with erythromycin-resistant C.jejuni strains. The strains from each flock were genotypically distinct, based on multi-locus sequence typing, performed at the lab of our collaborator, Dr. William Miller (USDA-ARS, California). A one-base pair mutation in the 23S rRNA gene in the large subunit of the Campylobacter ribosome was previously identified as the cause of erythromycin resistance in C. coli . In this study, we will determine if the turkey-derived C. jejuni strains share the same mutation in the 23S rRNA subunit of the ribosome as the previously studied C. coli strains. We will also determine if the erythromycin resistance in these C. jejuni strains is transferable by transformation to erythromycin-susceptible C. jejuni and C. coli.
Conventional turkey farms may use antibiotics to encourage growth and to treat disease in the birds. Over the years, Campylobacter strains have developed resistance to many of the antibiotics used. Antibiotic resistance can also be transferred from one strain to another rather easily due to Campylobacter’s inherent ability to exchange DNA between different strains. This resistance creates potential challenges as it may contribute to resistant strains entering the food supply and eventually infecting humans. C. coli from turkeys has been found to be resistant to erythromycin due to a mutation in its DNA while C. jejuni has lacked this resistance. However, 2 erythromycin resistant C. jejuni strains have been recovered from conventional turkey flocks by the Kathariou lab. In this study, the cause of the resistance will be investigated and the ability of the resistance to transform from one strain of C. jejuni to another, or to C. coli, will be tested. This would provide information about how the resistance is being acquired and if it has the potential to spread amongst other C. jejuni and C. coli strains.
This project is funded by a USDA NIFA grant that addresses risk factors for colonization of turkeys with campylobacter, including antibiotic-resistant strains. The research is in collaboration with Dr. Donna Carver (Extension Veterinarian at the Prestage Dept. of Poultry Science, North Carolina State University).