Update on the Recovery of Cold-Injured Campylobacter Jejuni from Inoculated Foods with the Blood-Free Enrichment System
T. T. Tran, FDA, Washington, DC 20204
The lowest recovery levels of cold-stressed Campylobacter jejuni in modified blood-free enrichment broth (mBFEB) and enriched cultures of crabmeat, mushrooms, raw milk, and raw oysters were determined. C. jejuni cells were cold-stressed before inoculation into mBFEB containing 10% food rinses. After a 24 and 48 h enrichment under ambient atmosphere, C. jejuni were isolated on modified CCDA-Preston agar. The overall mean recovery limit 50% end point (RL50) values, irrespective of food types and enrichment time, for the 5-, 10-, 20-, and 30-day stress procedure were 0.2, 1.3, 5.5 and 10.9 cfu / 5 g test portion, respectively. The effectiveness of the mBFEB decreased as injury time increased from 5 to 30 days. Further, with the increase of injury time, greater variations in recovery rates within and between foods were observed. Increase of enrichment time from 24 to 48 h did not appear to significantly improve (P>0.05) the recovery limits. This study indicates that C. jejuni cells survived well up to 30 days at 4-50 C and that the mBFEB system was effective in recovering cold-injured C. jejuni from the four foods studied at a contamination level of 1-20 cfu /5g food.