Hamburgers and Broiler Chickens as Potential Sources of Human Campylobacter Enteritis

Freezing to -18°C for 7 d reduced numbers of Campylobacter jejuni in artificially contaminated hamburgers by one log cycle. Minimal cooking rapidly eliminated the organism. No Campylobacters were detected in 50 samples of commercial ground meat. Ground meat dishes such as hamburgers are therefore unlikely vectors for human Campylobacter enteritis. Freezing of artificially contaminated chicken carcasses greatly reduced or eliminated C. jejuni initially present at 10⁵ cells/carcass. Minimal cooking for 20 min at 190°C eliminated all C. jejuni unless close pressing of limbs to the body preserved areas of uncooked skin. With commercial carcasses, 15/22 chilled and 6/37 frozen carcasses were contaminated with C. jejuni , maximum numbers being 10⁵ and 10³/carcass, respectively. Significant recontamination with C. jejuni could not be obtained by unhygienic handling after cooking of commercial chickens that had been moderately contaminated (10³ to 10⁴ cells/carcass), but substantial recontamination occurred with similar handling of carcasses that had initial heavy artificial contamination (10⁶ cells/carcass). The limited circumstances under which cooked poultry meat is likely to carry C. jejuni in significant numbers suggest a need for caution in ascribing outbreaks of Campylobacter enteritis to consumption of poultry.