Evaluation of Preston medium for detection of Campylobacter jejuni in vitroand in artificially and naturally contaminated poultry products

Abstract

A short pre-enrichment time (4 h at 37°C) allowed the recovery of low levels ofCampylo- bacter jejuni among an accompanying flora. Incubation time in a non-selective medium should not be further elongated because of outgrowth of the accompanying flora suppressing development of low numbers ofC. jejuni . Immediate selective enrichment (24 h at 42°C in Preston medium) also has the ability for detection of low levels of the pathogen bothin vitro (10–1000 cfu 100 ml −1) and in food samples (<10–1000 cfu 10 g −1). Exclusion of a prior non-selective enrichment step rendered this last procedure less laborious. Application of a 24 h selective enrichment in Preston medium at 42°C for detection of C. jejuni in poultry products identified 40% of the samples (n =60) to be contaminated with the pathogen. Elongation of incubation time to 48 h with or without blood supplementation to the Preston medium did not significantly improve detection of the pathogen. Supplementation of ferrous sulphate, sodium metabisulphite and sodium pyruvate, each at 0.25 g l −1and microaerophilic atmosphere fulfilled the requirement of enhancing the aerotolerance of C. jejuni and allowed recovery of the pathogen in 24 h.