Occurrence and diversity of Arcobacter spp. along the Llobregat River catchment, at sewage effluents and in a drinking water treatment plant

The presence of Arcobacter species in faecally contaminated environmental waters has previously been studied. However, the ability to eliminate Arcobacter during the water treatment processes that produce drinking water has been little studied. We have investigated the prevalence and diversity of Arcobacter spp. throughout the year at 12 sampling points in the Llobregat River catchment (Catalonia, Spain) including 3 sites at a drinking water treatment plant. Positive samples for Arcobacter spp., came predominantly from the most faecally polluted sites. Recovery rates from all sites were greater in the spring (91.7%) and summer (83.3%) than in autumn and winter (75.0% in both cases), but this trend was not statistically evaluated due to the limited number of samples. Among the 339 colonies analyzed, the most prevalent species by multiplex PCR and 16S rDNA restriction fragment length polymorphism were Arcobacter butzleri (80.2%), followed by Arcobacter cryaerophilus (19.4%) and Arcobacter skirrowii (0.3%). Isolates showed a high genotype diversity as determined by the enterobacterial repetitive intergenic consensus PCR. In fact, 91.2% (309/339) of the colonies had different genotypes, i.e. 248 of them among the 275 isolates of A. butzleri and 60 among the 63 isolates of A. cryaerophilus and 1 genotype of A. skirrowii. Arcobacter was never detected or isolated from finished drinking water, demonstrating that water treatment is effective in removing Arcobacter species.