Sensitivity of Three Methods Used in the Isolation of Arcobacter spp. in Raw Ground Pork

Abstract

Arcobacter, an aerotolerant Campylobacter-like organism, has been designated an emerging pathogen because of its newly recognized ability to cause diarrheal illness in both humans and animals and its presence in the human food supply. Because there is no standard isolation method for its detection, the true occurrence of this pathogen is largely unknown. In addition, the lack of a standardized isolation protocol limits the ability of investigators to compare field data. Arcobacter has been detected in whole muscle and ground pork at various levels by two different isolation methods (those of deBoer and Collins). In this study, these methods were tested along with the Johnson-Murano (JM) method, developed in our laboratory. The sensitivity of each method was tested for ground pork inoculated with Arcobacter butzleri and Arcobacter cryaerophilus 1A at levels of 104, 103, 102, and 101 CFU/g. Controls included tubes with uninoculated pork and broth tubes without pork. All samples that were morphologically similar to Arcobacter were analyzed by Gram staining and by catalase and oxidase reactions. Presumptive positive samples were confirmed by the polymerase chain reaction. The JM method was determined to be the most sensitive, detecting A. butzleri down to a level of 101 CFU/g in 100% of the samples and detecting A. cryaerophilus 1A at a level of 101 CFU/g in 75% of samples. In a pure buffer system, the Collins method was as effective as the JM method in isolating both organisms to levels of 101 cells per g.