Difficulty in recovering inoculated Campylobacter jejuni from dry poultry-associated samples

Abstract

We inoculated 5 cm2 of clean chick pads, 5 g of clean pine shavings, and fresh unsanitized broiler breeder eggshell halves with a cell suspension of Campylobacter jejuni in physiological saline. Inoculation levels were 102, 103, or 104 cells per sample. The samples were allowed to remain at room temperature for 15, 30, or 60 min before addition of enrichment broth. When chick pad samples were inoculated with 102 cells, by 15 min 40% of the samples had detectable levels of Campylobacter, and by 30 to 60 min Campylobacter could be detected in only 20% of the samples. With samples of pine shavings, only 25% of those inoculated with 103 cells were positive for Campylobacter after 15 min and only 5% were positive for Campylobacter after 30 min. When 104 cells were inoculated onto litter, Campylobacter was recovered from 20% of the samples at 15 min and 15% of the samples after 30 min. Eggshells were also found to be a harsh environment. When the inoculum was 102 at 15 min, 8 of 10 samples were positive for Campylobacter but at 60 min only 10% of the samples remained positive for Campylobacter. The current cultural methods may not be adequate for recovering low numbers of Campylobacter from dry samples. Campylobacter may be present but culturally undetectable in the commercial hatchery and hatchery environment.