Reference | Stapleton2010 (20024)

In vivo studies In Experiment 1, 1-day-of-age White Leghorn chicks (specific- pathogen-free (SPF) Lohmann, Germany; n = 88) that had been confirmed as Campylobacter free using cloacal swabbing were dosed at 1-day-of-age by gastric intubation with 3.7 · 10^6 CFU of Camp. jejuni 81116P. Caecal colonization (>1 · 10^7 CFU g)1) was confirmed in four of the birds at 14-days-of-age. The remaining birds were then divided into three groups (n = 28 per group) and treated with either 50, 125 or 250 ppm of enrofloxacin (Baytril) in drinking water (Baytril 10% Oral Solution, Bayer plc, Newbury, UK) for 5, 3 or 1 days, respectively. Four birds were killed from each group at 1, 2, 3, 7, 10, 21 and 35 days following the start of antimicrobial treatment. These timepoints were selected on the basis of preliminary experiments which indicated that resistance was observed in strains by 5 days post-treatment. In Experiment 2, 1-day-of-age chicks (n = 220) that had been confirmed as campylobacter free using cloacal swabbing were orally dosed at with 1.6 · 10^6 CFU Camp. jejuni 81116P. Colonization (>1 · 10^7 CFU g)1) was confirmed in four of the birds at 14-days-of-age. The remaining chicks were then randomly separated into six groups (n = 36 per group). The birds were treated for 3 days with 12, 25, 50, 125, 250 or 500 ppm of enrofloxacin in drinking water. Four birds from each group were killed at 2 and 6 h, and at 1, 2, 3, 7, 10, 15 and 35 days post-start of antimicrobial treatment.

Caecal contents were collected postmortem to determine colonization levels and for analysis of enrofloxacin and its metabolite ciprofloxacin by HPLC. Colonization levels per gram of caecal contents were determined for each of the four birds sacrificed at each time-point as described previously (Wassenaar et al. 1993) using the selective media 5% (w ⁄ v) blood agar containing Skirrow’s antibiotics (Oxoid, Basingstoke, UK) with 1% actidione (BASAC).

AST Method: None

Reference explicitly reports AST breakpoints: True

Reference reports using a MIC table: False