Submitted to: Microbial Ecology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: August 14, 2012
Publication Date: January 1, 2013
Citation: Meinersmann, R.J., Berrang, M.E., Little, E. 2013. Campylobacter spp. recovered from the Upper Oconee River Watershed, Georgia, in a four-year study. Microbial Ecology. 65(1):22-27. Interpretive Summary: Campylobacter jejuni is a bacterial pathogen that frequently causes diarrheal disease in humans. Human exposure is frequently via poultry products and is for this reason a food safety problem. However, the greater part of the life cycle of Campylobacter jejuni is not defined – the sources of chicken infection are unknown and passage of the organism outside of the chicken to human is uncharacterized. This study was designed to see if open waterways are part of the life cycle for the organism involved in human disease. Over the course of four years 560 water samples were taken from the Upper Oconee River Watershed from which 47 strains of Campylobacter were obtained. The strains were genetically typed in order to classify them by family lineages and this data was compared to types known to be found in chickens and humans. Of the recovered strains, some have previously been found in cattle and very few that were ever found in humans whereas most of the strains have only been associated with environmental water. This means that open water plays only a minor role if at all in the transmission of human associated Campylobacter.
Technical Abstract: Waterways should be considered in the migration routes of Campylobacter and the genus has been isolated from several water sources. Inferences on migration routes can be made from tracking genetic types in populations found in the habitats and testing how they are linked to other types. Water samples were taken over a 4-year period from waterways in the Upper Oconee River Watershed, Georgia, to recover isolates of thermophilic Campylobacter. The isolates were typed by multi-locus sequence typing (MLST) and analyzed to determine the overall diversity of Campylobacter in that environment. Forty-seven independent isolates were recovered out of 560 samples. Two isolates were C. coli, 3 isolates were putatively identified as C. lari, and the remaining 42 were C. jejuni. The C. jejuni and C. coli isolates were typed by the Oxford MLST scheme. Thirty unique sequence types (STs) were identified including 13 STs were not found before in the MLST database, including 24 novel alleles. Of the 17 previously described STs, 10 have been isolated from humans, 5 from environmental water and 5 from wild birds. Seven sites had multiple positive samples and on two occasions the same ST was isolated at the same site. The most common type was ST-61 with four isolates and the most common clonal complex was CC179 with 9 isolates. CC179 has been commonly associated with environmental water. Although some Campylobacter STs that were found in the Oconee River demonstrate widespread migration, most are tightly associated or unique to environmental water sources.