Figure 1. Restriction fragment length polymorphism (RFLP) patterns of representative Arcobacter isolates from male pigs. Reference strains of A. butzleri and A. cryaerophilus groups 1A and 1B are compared with field isolates. All of the field isolates hybridized with the probe and thus were verified as Arcobacter. The arrow indicates the position of the ;3.0-kb band that is characteristic of A. butzleri. Isolate SP51 exhibited this ;3.0-kb band and was thus verified as A. butzleri. On the basis of RFLP patterns, the remaining isolates could be identified as A. cryaerophilus 1A (SP32, SP35, and SP56) and 1B (SP31, SP34, SP57). Hind III digest of bacteriophage l is the size standard (kb). Aerotolerant Campylobacter-like organisms were first isolated from aborted bovine and porcine fetuses in the 1970s.2,3 These organisms were designated a single species, Campylobacter cryaerophila, on the basis of aerotolerance and the ability to grow at 25 C.9 In 1991, after extensive DNA homology studies, the species Campylobacter butzleri was proposed for the aerotolerant Campylobacter-like organisms isolated from human enteritis.7 On the basis of that study, two distinct groups of Campylobacter cryaerophila, 1A and 1B, were identified. In 1992, the genus Arcobacter was proposed to encompass the aerotolerant microorganisms of 4 species: Arcobacter nitrofigilis, A. cryaerophilus, A. butzleri, and A. skirrowii.14,16 The species of Arcobacter associated with human or animal disease are Arcobacter, A. cryaerophilus (groups 1A and 1B), and A. skirrowii. Of these, A. butzleri is isolated most frequently from human infections. Arcobacter butzleri has been isolated from water, poultry, and ground pork, all of which pose a risk for human infection.1,6,12,18 Previous studies have detected Arcobacter in ground pork samples obtained from midwest slaughter facilities, with recoveries from the 5 plants ranging from 0 to 90%.1 Whether management practices at the source farms or the sanitary conditions during slaughter influenced the prevalence of Arcobacter spp. in ground pork was not determined. Aerotolerant Campylobacter-like organisms have been isolated from aborted and normal porcine fetuses, sows with reproductive problems, and clinically healthy specific-pathogen-free pigs.2–5,9,10,17,18,20 In one study, 90% of Campylobacter spp. isolated from fetuses and 78% of Campylobacter spp. isolated from porcine vaginal swabs were identified as C. cryaerophila. Strains from reproductively impaired and