A METHOD FOR THE ISOLATION OF CAMPYLOBACTER JEJUNI FROM POULTRY PRODUCTS BY SELECTIVE ENRICHMENT

RONALD DAVID WESLEY, Purdue University

Abstract

Campylobacter jejuni, which has been shown to be the most commonly isolated pathogen from hospital patients with gastroenteritis, is frequently found in chicken carcasses, cut-up parts and other poultry products. A direct selective enrichment procedure was developed for the isolation of C. jejuni from poultry products. The selective enrichment medium consisted of (amount per liter): tryptose (20 g), yeast extract (2.5 g), sodium chloride (5 g), ferrous sulfate (0.25 g), sodium metabisulfite (0.25 g), sodium pyruvate (0.25 g), bicine (10 g) and agar (1.0 g); hematin solution (6.25 ml; prepared by dissolving 0.032 g of bovine hemin in 10 ml of 0.15 N sodium hydroxide solution and autoclaving at 0.35 kg/cm('2) for 30 min), rifampicin (25 mg), cefsulodin (6.25 mg) and polymyxin B sulfate (20,000 IU) were added after sterilizing the medium; pH was adjusted (20,000 IU) were added after sterilizing the medium; pH was adjusted to 8.0. Samples were enriched in the above medium at 42(DEGREES)C for 48 h in an atmosphere of 5% O(,2), 10% CO(,2) and 85% N(,2). Enrichment cultures were streaked onto a plating medium composed of Brucella agar, hematin solution, ferrous sulfate, sodium metabisulfite, sodium pyruvate and the above antibiotics. Plates were incubated under the same conditions as above. Suspect colonies were confirmed as C. jejuni by morphological examination, growth characteristics and biochemical tests. The method yielded 25 isolates of C. jejuni from 50 samples of retail cut-up chicken and chicken parts, while a more complex method involving filtration, centrifugation, selective enrichment under a flowing atmosphere, and membrane filtration yielded only six positives from the same samples. The new isolation procedure was particularly effective in isolating C. jejuni in the presence of large numbers of Pseudomonas aeruginosa. The procedure was found to yield quantitative recoveries of C. jejuni from artificially inoculated (less than one cell/g) chicken parts, chicken livers and mechanically deboned chicken meat as determined by a 3-tube most probable numbers technique. Examination of commercially processed chickens showed that CO(,2) packaging had little or no effect on survival of C. jejuni during transport and refrigerated storage.

Degree

Ph.D.

Subject Area

Food science

COinS