|Vereen jr, Ethell|
Submitted to: Applied and Environmental Microbiology
Publication Type: Peer reviewed journal
Publication Acceptance Date: 3/20/2007
Publication Date: 3/20/2007
Citation: Vereen Jr, E., Lowrance, R.R., Cole, D.J., Lipp, E.K. 2007. Distribution and Ecology of Campylobacters in Coastal Plain Streams. Applied and Environmental Microbiology. 73:1395-1403. Interpretive Summary: Campylobacters comprise a group of closely related bacteria that primarily colonize the gastrointestinal tracts of a variety of host species. They are the most common cause of bacterial intestinal distress globally. Although assumed to be a food-borne disease primarily associated with poultry and poultry products, illness from Campylobacter increases in the summer months, suggesting that exposures through outdoor contact also may be important. In this study we investigated the distribution and seasonality of Campylobacter in the streams of a rural southeastern Georgia (USA) mixed-use watershed and consider potential sources of Campylobacters that would explain the seasonality of infection. The watershed (Satilla River basin) is home to dozens of chicken houses producing broilers and to a broiler processing plant that discharges to the city Wastewater Treatment Plant (WWTP). Most agricultural land in the watershed receive poultry litter application. We sampled streams in the watershed, and in a near by less agricultural (control) watershed for a year. We also sampled one site on a stream directly below the WWTP. We also tested how well the bacteria survived in stream water under summer and winter temperatures in the lab. Detection of Campylobacter in streams was highly associated with discharge from the WWTP and moderately associated with proportion of agricultural land in the watershed. Despite a low persistence under summer-time temperatures in the laboratory, Campylobacters were more frequently isolated and present larger numbers in streams during the summer months. This suggests that loading from both human and domestic animal waste may be high in this watershed. Mixed-use watersheds, supporting agriculture production, human populations and wildlife may be at high risk for contamination by Campylobacters. In summary, campylobacters were frequently present along agricultural and sewage impacted stretches of streams in the Satilla River Watershed in southeastern Georgia and continued environmental monitoring will shed light on a number of uncertainties concerning contamination, persistence, and potential sources of Campylobacter.
Technical Abstract: Campylobacter is the leading cause of bacterial associated diarrhea in the United States and most developed countries. While considered a foodborne disease, many clinical cases cannot be linked to a food source. In rural and agrarian areas environmental transmission may be an important contributor to case loads. Here we investigated the waterborne prevalence of campylobacters in a mixed-use rural watershed in the coastal plain of southern Georgia (USA). Six sites representing varying degrees of agricultural and human influence were surveyed bi-weekly to monthly for one year for culturable thermophilic campylobacters and other measures of water quality. Campylobacters were frequently present along agrarian and sewage impacted stretches of streams. Mean campylobacter counts and overall prevalence were highest downstream from a wastewater treatment plant (WWTP) that handled both human and poultry slaughterhouse waste (<595 CFU ml-1, 100% positive); concentrations were significantly higher than the other four upstream sites (p<0.05). Counts were significantly correlated with fecal coliform bacteria, conductivity, pH, and nutrients (NO3-, PO43-, and NH3). Despite a low persistence in vitro under warm temperatures (25o C) (5 days of survival), in the field campylobacters were more frequently isolated and present in larger numbers during the summer months. A multivariate model showed that levels were significantly influenced by increasing precipitation, which also peaked in the summer. Results indicate that loading from both human and domestic animal waste may be high in this watershed during summer months. Mixed-use watersheds, supporting agriculture production, human populations and wildlife may be at risk for contamination by campylobacters and may serve as an important human exposure route.