Methods for the detection of thermotolerant campylobacters in foods: results of an inter-laboratory study.

An inter-laboratory comparison of three methods for the detection of thermotolerant campylobacters is described. One of two proposed by the International Standards Organisation was significantly better for detecting campylobacters in minced chicken skin naturally contaminated at levels of either 2 or 10 cells per 10 g, but involved extensive manipulations not likely to be well received in a busy laboratory. This method yielded 18% false negative results compared with 48-54% for the other two but also gave 8% false positive results. Pre-enrichment of samples with a gradual addition of antibiotics to suppress competing organisms seemed to improve the recovery of campylobacters, as did a non-selective blood agar isolation medium used in combination with a membrane filtration technique.