Arcobacter species are Gram-negative rods that have been implicated in food- and waterborne illness. Although various cultural isolation methods have been proposed, the current procedures are unable to fully suppress growth of background microbiota present in food samples which inhibits Arcobacter isolation. The purpose of this study was to develop a selective enrichment broth and chromogenic plating medium to detect three Arcobacter species that have been recognized as emerging foodborne pathogens: Arcobacter butzleri , Arcobacter cryaerophilus and Arcobacter skirrowii . The developed Nguyen-Restaino-Juárez Arcobacter detection system consists of a selective enrichment broth (NRJ-B) and a selective/differential plating media (NRJ-M). The protocol of the detection method was determined by evaluating growth of A. butzleri , A. cryaerophilus and A. skirrowii under various temperature (30, 35 and 42ᴼC) and incubation (aerobic, microaerophilic and anaerobic) conditions. Additionally, 47 Arcobacter strains and 39 non- Arcobacter strains were tested in the inclusivity and exclusivity evaluations of NRJ-B and NRJ-M. Overall, the study determined the optimal growth conditions of Arcobacter species using the NRJ- Arcobacter detection system was aerobic incubation at 30ᴼC. NRJ-B supported good growth of A. butzleri , A. cryaerophilus , and A. skirrowii while effectively suppressing growth of non- Arcobacter strains after 48 h. Furthermore, NRJ-M yielded 97.8% inclusivity and 100.0% exclusivity using the tested strains and resulted in salmon-pigmented Arcobacter colonies (1.0 to 1.5 mm in diameter) after 72 h. The novel protocol is the first to develop a chromogenic plating media for the isolation of Arcobacter species. This simple and reliable test method would greatly contribute to understanding the distribution of pathogenic Arcobacter species in food samples.
P064: Direct identification of vancomycin-resistant enterococci from selective enrichment broth by mass spectrometry
