Oxytetracycline-Resistant Coliforms in Commercial Poultry Products

Abstract

The presence of oxytetracycline-resistant bacteria was investigated with commercially frozen chicken thighs and drumsticks. Bacterial flora were surveyed by means of total and coliform counts with Tryptone Glucose Extract Agar and Desoxycholate Agar, respectively. After counting, the Desoxycholate Agar plates were replicated on the same medium containing 25, 50, 75, and 100 ppm of oxytetracycline. Resistant colonies were found on all samples that were replicated. Of 2613 colonies isolated on Desoxycholate Agar, 47.8% grew in the presence of 25 ppm of oxytetracycline. From 50 to 100 ppm, the number of resistant isolates remained essentially the same, near 34%. Of 812 colonies of antibiotic-resistant bacteria identified with dulcitol-lactose-iron-agar, 82.5% were paracolons, 13.7% were pseudomonads, and 3.8% were Escherichia or Aerobacter . Bacteria resistant to oxytetracycline were shown to be present on commercially processed chicken. The origin of the resistance to oxytetracycline was not established; however, since the antibiotic was not used during processing, it appeared that these antibiotic-resistant bacteria arose in the intestines of the chickens as a result of feed which contained antibiotic. This is supported by a comparison with the antibiotic resistance of coliforms from chickens raised on feed both with and without oxytetracycline, for the percentages of resistant colonies are similar in both commercial chicken and chicken raised on feed containing the antibiotic.

Tracking Oxytetracyline Mobility Across Environmental Interfaces by Second Harmonic Generation

“…Evidence of bacterial antibiotic resistance has been reported for soils exposed to oxytetracycline-treated swine manure . This is not surprising, as resistance to oxytetracycline was documented only a few years after its introduction as a commercial antibiotic, , and its usefulness in treating illnesses has diminished significantly in recent years. , Resistance to tetracyclines is currently believed to occur through three possible pathways: (1) tetracycline efflux, which lowers the concentration of tetracycline in the cell, (2) production of ribosomal protection proteins, and (3) enzymatic inactivation of tetracycline. , Interestingly, the nontherapeutic use of tetracycline was banned by the United Kingdom in the early 1970s, whereas its agricultural use continues in the United States…”