Reference | Takahashi2005 (20026)

Four groups of fifteen 3-day-old specific pathogen-free chickens (White Leghorn; Nippon Institute for Biological Science, Tokyo, Japan) were reared separately in an infection-free isolator. Throughout the experiment, the chickens were fed a standard antibiotic-free starter/grower diet and given access to feed and water ad libitum. To help avoid the introduction of exogenous Campylobacter via the drinking water and/or the feed, we provided sterile water and the feed which was pelleted with continuous heat treatment in the manufacturing process, and stored exclusively under clean conditions during the experiments. Ten faecal samples of 14-day-old chickens were taken at random on the floor of each isolator and checked for the absence of Campylobacter. During the following experimental periods, freshly voided faecal samples were taken at random at the defined intervals on the floor of isolators. In study 1 (two groups included), C. jejuni ATCC 33560T was added to drinking water at a concentration of 106 cfu ml)1 when the chickens were 17 days old. In study 2 (two groups included), the same strain was added twice to drinking water at a concentration of 107 and 108 cfu ml)1 when the chickens were 18 and 23 days old respectively. Prior to the administration of enrofloxacin, 10 faecal samples of chickens in each group were checked for the presence of Campylobacter. To one group in each study 50 ppm enrofloxacin (Baytril 10% solution; Bayer, Leverkusen, Germany) in drinking water was administered for three consecutive days. In studies 1 and 2, the administration of enrofloxacin was started when the chickens were 24 and 32 days old respectively. The remaining groups received no antimicrobials and acted as control animals. Ten faecal samples from each group were collected just before administration (day 0) and 1, 2, 4, 7, 14 and 21 days after initiating administration in study 1, and just before administration (day 0), 1, 3, 4, 8, 14 and 21 days after initiating administration in study 2 (Fig. 1).

In both studies, all the chickens were necropsied and the caecal contents were collected from 10 chickens per group on day 28. In both studies, on days 0, 1 and 28, the viable number of C. jejuni in the faeces or caecal contents was determined by standard bacterial counting techniques on mCCDA. In principle, two isolates per sample were used for antimicrobial susceptibility testing. These isolates were kept suspended in 15% glycerine to which buffered peptone water (Oxoid) had been added, and then stored at )80Cuntil they were used for tests.

AST Method: None

Reference explicitly reports AST breakpoints: True

Reference reports using a MIC table: True