Conventional detection and confirmation methods for Campylobacter jejuni are lengthy and tedious. A rapid hybridization protocol in which a 1,475-bp chromogen-labelled DNA probe (pDT1720) and Campylobacter strains filtered and grown on 0.22-m-pore-size hydrophobic grid membrane filters (HGMFs) are used was developed. Among the environmental and clinical isolates of C. jejuni, Campylobacter coli, Campylobacter jejuni subsp. doylei, Campylobacter lari, and Arcobacter nitrofigilis and a panel of 310 unrelated bacterial strains tested, only C. jejuni and C. jejuni subsp. doylei isolates hybridized with the probe under stringent conditions. The specificity of the probe was confirmed when the protocol was applied to spiked skim milk and chicken rinse samples. Based on the nucleotide sequence of pDT1720, a pair of oligonucleotide primers was designed for PCR amplification of DNA from Campylobacter spp. and other food pathogens grown overnight in selective Mueller-Hinton broth with cefoperazone and growth supplements. All C. jejuni strains tested, including DNaseproducing strains and C. jejuni subsp. doylei, produced a specific 402-bp amplicon, as confirmed by restriction and Southern blot analysis. The detection range of the assay was as low as 3 CFU per PCR to as high as 10 5 CFU per PCR for pure cultures. Overnight enrichment of chicken rinse samples spiked initially with as little as ϳ10 CFU/ml produced amplicons after the PCR. No amplicon was detected with any of the other bacterial strains tested or from the chicken background microflora. Since C. jejuni is responsible for 99% of Campylobacter contamination in poultry, PCR and HGMF hybridization were performed on naturally contaminated chicken rinse samples, and the results were compared with the results of conventional cultural isolation on Preston agar. All samples confirmed to be culture positive for C. jejuni were also identified by DNA hybridization and PCR amplification, thus confirming that these DNA-based technologies are suitable alternatives to time-consuming conventional detection methods. DNA hybridization, besides being sensitive, also has the potential to be used in direct enumeration of C. jejuni organisms in chicken samples. Campylobacter jejuni accounts for Ն95% of all human campylobacterosis infections, which are mainly due to the consumption of raw milk and undercooked chicken (8). Due to the fastidious nature of campylobacters and their tendency to be easily suppressed by other enteropathogens, conventional detection of campylobacters in foods involves lengthy selective cultural enrichment (10). Subsequent identification and confirmation at the species level with traditional fermentation tests are limited since campylobacters are inherently biochemically inert. Discrimination between C. jejuni and Campylobacter coli is based solely on the hippurate hydrolysis test. The reliability of this test has been brought into question with the isolation of C. jejuni strains incapable of hydrolyzing hippurate (11). These limitations have resulted in efforts...

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