title: Development of a rapid and inexpensive assay for the nonspecific detection of antimicrobial residues in chicken egg yolks and neonatal yolk sacs.
abstract: Competitive exclusion of intestinal pathogens by administration of beneficial and defined cultures of normal intestinal microflora is a safe and effective means of reducing the incidence and severity of chick infections with Salmonella and other intestinal pathogens. It is important that competitive exclusion cultures not carry genetic material (e.g., plasmids), which could transfer antibiotic resistance to other microflora, including pathogens. As such, safe and effective competitive exclusion cultures must be sensitive to commonly used antimicrobial agents. By necessity, intentional or accidental exposure of these beneficial microflora to antibiotics will reduce or eliminate the protection provided by competitive exclusion culture establishment. As antibiotic residues can be present from embryonic, hatchling, or maternal administration, a rapid and sensitive assay for the nonspecific detection of residues, which could interfere with competitive exclusion culture establishment, is needed. This study was conducted to develop a rapid and inexpensive bioassay to detect multiple antimicrobial residues in egg yolk and neonatal yolk sacs. Aerobic bacterial strains with known sensitivity to several antibiotics used by the poultry industry were selected and individually compared for sensitivity to enrofloxacin, gentamicin, tetracycline, ceftiofur, and tylosin concentrations in egg yolks. This assay was found to be relatively sensitive for the detection of these antimicrobials, and detection of residues was associated with reduced competitive exclusion culture (PREEMPT) establishment in one experiment. Importantly, this assay can be implemented with minimal training or equipment under commercial hatchery practices and could be used to determine embryo groups, in advance of hatch, that are not suitable candidates for competitive exclusion treatment in the hatchery.
authors.affiliation: Departments of Veterinary Pathobiology and Poultry Science, Texas Agricultural Experiment Station, College Station, Texas 77843, USA.
authors.forename: D Y
authors.initials: DY
authors.lastname: Caldwell
authors.forename: J L
authors.initials: JL
authors.lastname: McReynolds
authors.forename: S D
authors.initials: SD
authors.lastname: Young
authors.forename: D J
authors.initials: DJ
authors.lastname: Caldwell
authors.forename: B M
authors.initials: BM
authors.lastname: Hargis
mesh_terms: D000818:Animals; D019072:Antibiotic Prophylaxis / Q000662:veterinary*; D002645:Chickens; D004350:Drug Residues / Q000302:isolation & purification*; D004352:Drug Resistance, Microbial; D004530:Egg Yolk / Q000737:chemistry*; D006801:Humans; D012680:Sensitivity and Specificity; D015017:Yolk Sac / Q000737:chemistry*