Campylobacter jejuni and Campylobacter coli are Gram-negative, curved or spiral motile rods with a single polar flagellum that requires an atmosphere with reduced O2 and increased CO2 . The optimal atmosphere for Campylobacter growth is 50/0 0b 100/0 CO2 , and 850/0 N2 ; thus, this organism is considered a capriophile (carbon dioxide loving). In foods, this organism is not likely to grow under typical storage conditions. 16 The optimum growth temperature is 42 to 43°C, and its growth range is between 30 to 440 C.16 These organisms are fairly frail in food and do not survive well outside their host's intestinal tract. These organisms are sensitive to freezing and die at room temperature. However, survival is increased at refrigeration temperatures, and food for analysis should be held at 4°C (and not be frozen). Even greater survival of Campylobacter organisms was found when food samples were stored under 100% N2 with 0.010/0 sodium bisulfite at 4°C.16 Analyses of food samples should be performed as soon as possible to prevent overgrowth of Campylobacter by psychrotrophic microflora. 17
C. jejuni is almost exclusively associated with warm-blooded animals. A large percentage of all major meat animals have been shown to have this organism in their feces. 18 In general, fresh poultry tends to have a higher carriage of this organism than other meats. 18
There are multiple methods that can be used to grow Campylobacter under a microaerobic atmosphere. The ideal method is to evacuate air and then fill a growth chamber or inflate a sterile bag from a gas canister with the appropriate gas mixture (50/0 0b 100/0 COb and 85% N2). Alternative methods include using commercially available gas generation packs for Campylobacter (such as those manufactured by BBL and Oxoid) or using low levels of anaerobic gas generation packs. 16 Both systems utilize single-use gas generator envelopes and catalyst pellets (palladium). To use one of these systems, the samples are placed in the "anaerobe" jar system. Depending upon the size of the jar (and type of generator envelope), one to three generator envelopes may be needed to create the microaerobic environment. The generator envelopes are cut open and placed in the jar in a vertical position. Then, 10 ml of water are added to each, and the jar is sealed. Once the jar is sealed, the
borohydride tablet, producing hydrogen that subsequently combines with oxygen in the presence of the palladium catalyst producing water (thus reducing O2 in the atmosphere). The generator envelope also has a s'odium bicarbonate and citric acid tablet, which in the presence of water produces CO2. The entire jar system is placed into an incubator.