Studies on the presence and survival of campylobacter species in the Sydney rock oyster (Crassostrea commercialia)

A direct enrichment procedure has been developed for selectively recovering low numbers of Campylobacter jejuni and Campylobacter coli from oyster tissue. This procedure makes use of a selective enrichment step, using a broth medium composed of 2% proteose peptone, 1% yeast extract, 0.2% potassium L-aspartate, 0.25% sodium chloride as basal medium (PYA broth)plus 0.2% bacteriological charcoal, polymyxin (5000 IU/ litre), cefoperazone(30 mg/litre), trimethoprim (10 mg/litre), cycloheximide (50 mg/litre), sodium pyruvate (0.25g/litre), sodium metabisulphate (0.25g/litre) and ferrous sulphate (0.25g/litre). In this study the procedure has been used to study the occurrence of thermophilic campylobacters in Sydney rock oysters. Seventy nine samples were screened during the winter months of April to July in 1985. Approximately 8% of the samples contained C.jejuni and 6% of the samples were positive for C.coli. The survival of C.jejuni and C.coli in the Sydney rock oyster was also investigated and results discussed. In contaminated shell stock stored at 20 and 30 degrees Centigrade, C.jejuni and C.coli survived for periods varying from 2 to 9 days. The failure of the organism to multiply in oyster tissue at any of these temperatures studied is an important phenomenon