|Miller, William - Bill|
Submitted to: Applied and Environmental Microbiology
Publication Type: Peer reviewed journal
Publication Acceptance Date: 12/20/2010
Publication Date: 12/30/2010
Citation: Sloane, J.Y., Leatherbarrow, A.J., Winstanley, C., Bennett, M., Hart, C.A., Miller, W.G., Williams, N. 2010. A comparison of Arcobacter isolation methods and the diversity of Arcobacter spp. in Cheshire, UK. Applied and Environmental Microbiology. 10.1128/AEM.01964-10. Interpretive Summary: Arcobacters are close relatives of Campylobacters and Helicobacters, and like these related foodborne bacterial pathogens can cause gastroenteritis in humans. However, unlike the major Campylobacter and Helicobacter species, relatively little is known about Arcobacter. Arcobacters are associated generally with aquatic environments but have been isolated with increasing frequency from food, food animals and food production facilities. Often, due to their growth at lower temperatures and different antibiotic resistance profiles, arcobacters are overlooked both clinically and as food-borne contaminants. A recent prioritization of foodborne diseases ranked Arcobacter butzleri as a microbe of “significant importance” This study tested five different existing isolation methods to determine the best course of isolating food-associated Arcobacter species. All five methods had different outcomes both in the numbers and types of arcobacters isolated; however, an optimal isolation method was identified. Typing of A. butzleri strains isolated in this study indicated that the isolation methods were not biased towards a subset of Arcobacter strains. It was also determined that sample freezing prior to isolation reduced recovery of arcobacters.
Technical Abstract: Aims: The aims of this study were firstly to compare five published methods for the isolation of Arcobacter spp. from animal faeces in order to determine the most sensitive and specific method. Secondly, we analyzed the resulting isolates by multi-locus sequence typing (MLST) in order to investigate the diversity of the isolates recovered. Thirdly, we investigated the ability to recover Arcobacter spp. from frozen faecal samples. Methods: 77 faecal 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 A. butzleri isolates were analyzed using an MLST scheme. The survival of Arcobacter spp. in frozen samples was investigated by freezing the faecal samples at -80°C for seven days, and then applying the same five isolation methods. Results: The most sensitive and specific method used an Arcobacter-specific broth in conjunction with mCCDA agar with added antibiotics. Freezing of faecal 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). Conclusions: We have identified the most sensitive and specific method for the isolation of Arcobacter spp. from animal faeces and demonstrated that the freezing of faecal samples prior to isolation reduces arcobacter recovery. MLST analysis of the isolates revealed a high level of diversity.