ARS | Publication request: Recovery of viable non-culturable dry stressed Campylobacter jejuni from inoculated samples utilizing a chick bioassay

Submitted to: Campylobacter Helicobacter and Related Organisms International Workshop
Publication Type: Abstract Only
Publication Acceptance Date: June 8, 2007
Publication Date: September 2, 2007
Citation: Richardson, L.J., Cox Jr, N.A., Buhr, R.J., Hiett, K.L., Bailey, J.S., Harrison, M.A. 2007. Recovery of viable non-culturable dry stressed Campylobacter jejuni from inoculated samples utilizing a chick bioassay. Campylobacter Helicobacter and Related Organisms International Workshop, Zoonoses Public Health. 54(Sl):119. P#367.

Technical Abstract: Studies have shown that stressed Campylobacter cells in aquatic environments can be viable non-culturable. Preliminary experiments have shown in a matter of hours, certain Campylobacter jejuni strains are not readily recovered from dry stressed samples by current methodology procedures. The objective of the study was to determine whether C. jejuni strains that are non-culturable due to a dry stressed environment can be recovered utilizing a chick bioassay. In experiment 1, sterile chick pads (PP) were cut into 1 in. squares and inoculated with a 103 (L) or 106 (H) CFU/mL of a cocktail of three characterized field strains of C. jejuni. In experiment 2, filter papers (FP) were utilized and the above procedures performed. The samples were left at room temperature and exposed to atmospheric conditions for up to 24 hrs. At 0, 2, 4, 6, and 24 hrs post inoculation, five different enrichment methodology procedures were utilized to determine the culturability of the inoculums. For the H-PP sample, C. jejuni were detected only at 2 and 4 hr drying by conventional cultural methods. For the L-PP, L-FP, and H-FP samples, no C. jejuni were recovered by conventional cultural methods even at 2 hr drying. For the chick bioassay, 6 hr dry-stressed papers were utilized. The papers were homogenized and administered orally and intracloacally to day-of-age chicks which were housed in sterile confinement units. Seven days post-inoculation, chicks were euthanized, ceca aseptically removed, and analysis performed. For the chick bioassay, the non-culturable strains on the L-FP, H-FP, and H-PP were recovered from the chicks at a rate of 11%, 3%, and 6% respectively. This study provides evidence that certain strains of C. jejuni subjected to dry stress can still be shown viable by utilizing a chick bioassay.