Comparison of Arcobacter isolation methods, and diversity of Arcobacter spp. in Cheshire, United Kingdom

The aims of this study were, firstly, to compare five published methods for the isolation of Arcobacter spp. from animal feces in order to determine the most sensitive and specific method. Second, we analyzed the resulting isolates by multilocus sequence typing (MLST) in order to investigate the diversity of the isolates recovered. Third, we investigated the ability to recover Arcobacter spp. from frozen fecal samples. Seventy-seven fecal samples from cattle, sheep, and badgers were subjected to five isolation methods, based on published methods for the isolation of Arcobacter and Campylobacter spp. Thirty-nine Arcobacter butzleri isolates were analyzed using a multilocus sequence typing scheme. The survival of Arcobacter spp. in frozen samples was investigated by freezing the fecal samples at -80°C for 7 days and then applying the same five isolation methods. The most sensitive and specific method used an Arcobacter-specific broth in conjunction with modified charcoal cefoperazone deoxycholate agar (mCCDA) with added antibiotics. Freezing of fecal samples led to a reduction in the recovery of Arcobacter spp. by approximately 50%. The 39 allelic profiles obtained by MLST could be divided into 11 sequence types (STs). We have identified the most sensitive and specific method for the isolation of Arcobacter spp. from animal feces and demonstrated that the freezing of fecal samples prior to isolation reduces arcobacter recovery. MLST analysis of the isolates revealed a high level of diversity.