SALMONELLA, CAMPYLOBACTER AND ENTEROCOCCUS SPP., THEIR ANTIMICROBIAL RESISTANCE PROFILES AND THEIR SPATIAL RELATIONSHIPS IN A SYNOPTIC STUDY OF THE UPPER OCONEE RIVER BASIN

Authors: Meinersmann, Richard - Rick; Berrang, Mark; Jackson, Charlene; Cray, Paula; Ladely, Scott; LITTLE, E - UNIVERSITY OF GEORGIA; Frye, Jonathan; MATTSSON, B - UNIVERSITY OF GEORGIA

Submitted to: Microbial Ecology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/12/2007
Publication Date: 8/9/2007
Citation: Meinersmann, R.J., Berrang, M.E., Jackson, C.R., Cray, P.J., Ladely, S.R., Little, E., Frye, J.G., Mattsson, B. 2007. Salmonella, campylobacter and enterococcus spp., their antimicrobial resistance profiles and their spatial relationships in a synoptic study of the upper oconee river basin. Microbial Ecology. 55(3):444-452.

Interpretive Summary: Many bacteria can be found in river water and many of these are associated with human disease. It has been suggested that environmental water provides places for bacteria to exchange genes that are important for causing disease or causing resistance to antibiotics. To begin to test this suggestion it is important to understand the sources and distribution of bacteria in the waterways. This study was focused on determining the distribution of three bacteria associated with disease: Salmonella, Campylobacter and Enterococcus. Samples were taken from 84 sites of the Upper Oconee River Watershed and examined for the presence of these bacteria. The antibiotic resistance properties of each bacteria was also tested. Twelve sites were positive for Campylobacter, 71 sites were positive for Enterococcus, and 62 sites were positive for Salmonella. Antibiotic resistance was uncommon among the Campylobacter and Salmonella and did not reflect what is commonly seen in human or veterinary medicine. Enterococcus had a substantial amount of antibiotic resistance, but the number of resistance properties per strain was less than commonly seen in medical isolates. Most of the species or types within the species of the isolated bacteria showed clustering within a range of about 5 to 6 kilometers. The data from this study does not suggest that waterways are important sites for emergence of new types of bacteria, but my still be important in transmission.

Technical Abstract: Rivers may serve as reservoirs for enteropathogens and antimicrobial resistance genes. The presence of Salmonella, Campylobacter and Enterococcus spp. and the antimicrobial resistance phenotypes carried by these organisms was evaluated for the Upper Oconee River basin, a small river in the lower piedmont of northeastern Georgia, USA. Eighty-four samples were obtained during a three hour period on a spring day (April 2005) in an approximately 30 by 20 km region. Campylobacter spp. was isolated at 12 sites. Three of the Campylobacter isolates were resistant to tetracycline. Three short-variable region (SVR) subtypes of Campylobacter were found at more than one site, two types were found twice and one subtype was found three times. Enterococcus was isolated at 71 sites. E. casseliflavus was the most common species. Based on species identification and antimicrobial resistance patterns, twenty-four types of Enterococcus were found. Salmonella was isolated from 62 sites. Of the 19 Salmonella serovars that were isolated, serovar Muenchen accounted for about 20% of the isolates. The next three most common serovar isolates, Rubislaw, Hartford, and Give, accounted for about 44% of the river isolates. Antimicrobial resistance profiling offered limited differentiation of Salmonella isolates because only seven isolates were resistant to any antimicrobial. The sites for isolation of Salmonella, Campylobacter, or Enterococcus did not correlate with each other or with the the total coliform number or Escherichia coli count for the site. However, isolates of some of the same species and type occurred in clusters that were restricted to areas within 5 to 6 kilometers.