title: Campylobacter coli naturally resistant to elevated levels of gentamicin as a marker strain in poultry research.
abstract: Campylobacter inoculation studies are limited without a suitable marker strain. The lurpose of this study was to screen Campylobacter strains (n=2073) obtained from poultry carcass rinses through the Centers for Disease Control and Prevention's National Antimicrobial Resistant Monitoring System for resistance to gentamicin and evaluate one strain's efficacy as a marker. A C. coli strain was found resistant to gentamicin at >32 microg/ml. Gentamicin was incorporated into media (Campy-Cefex agar, Brucella agar, and blood agar) from 0 to 1000 microg/ml, and the upper level of gentamicin resistance was determined. C. coli strain's upper level of growth on Campy-Cefex plates, blood agar plates, and Brucella agar plates was 400, 300, and 200 pg/ml, respectively. Ceca and postpick carcass rinses were obtained and streaked onto Campy-Cefex agar at the above gentamicin levels to evaluate background microflora exclusion. Campy-Cefex agar containing gentamicin at 100 ag/ml prevented from the ceca, and reduced from the rinse, background microflora. The C. coli strain was orally or intracloacally inoculated into chicks. At 1, 3, and 6 weeks of age, inoculated broilers were removed and several tissue types sampled for the presence of the marker strain. At 6 weeks of age, 10 additional noninoculated penmates were sampled. The C. coli strain colonized chicks, disseminated to body tissues, colonized penmates, and persisted throughout the 6-week grow-out. The C. coli strain's unique characteristic, being resistant to high levels of gentamicin, allows for a marker that can be used in a wide range of Campylobacter research projects.
authors.affiliation: U.S. Department of Agriculture, Agricultural Research Service, Poultry Microbiology Safety Research Unit, Russell Research Center, 950 College Station Road, Athens, Georgia 30605, USA. nelson.cox@ars.usda.gov
authors.forename: N A
authors.initials: NA
authors.lastname: Cox
authors.forename: L J
authors.initials: LJ
authors.lastname: Richardson
authors.forename: M E
authors.initials: ME
authors.lastname: Berrang
authors.forename: R J
authors.initials: RJ
authors.lastname: Fedorka-Cray
authors.forename: R J
authors.initials: RJ
authors.lastname: Buhr
mesh_terms: D000362:Agar; D000818:Animals; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D017000:Campylobacter coli / Q000187:drug effects*; D002645:Chickens / Q000382:microbiology*; D015169:Colony Count, Microbial; D003470:Culture Media / Q000737:chemistry; D004305:Dose-Response Relationship, Drug; D024881:Drug Resistance, Bacterial / Q000235:genetics*; D005506:Food Contamination / Q000032:analysis; D005516:Food Microbiology; D005839:Gentamicins / Q000494:pharmacology*
chemical_list: D000900:Anti-Bacterial Agents; D003470:Culture Media; D005839:Gentamicins; D000362:Agar