Project ID: 2006AR131B

Title: Occurrence and antibiotic resistance in fecal indicator bacteria upstream and downstream of wastewater treatment plants in northwest Arkansas

Project Type: Research

Start Date: 03/01/2006

End Date: 02/28/2007

Congressional District: 3rd

Focus Categories: Surface Water, Water Quality, Management and Planning

Keywords: fecal indicator bacteria, antibiotic resistance, surface water, wastewater treatment effluent

Principal Investigators: Savin, Mary Cathleen (University of Arkansas); Haggard, Brian E. (USDA-ARS-PPPSRU)

Federal Funds: $17,819

Non-Federal Matching Funds: $36,509

Abstract: The proposed research will investigate the occurrence of Enterococcus faecalis and total coliform bacteria, Escherichia coli in particular, as indicators of fecal contamination. Because the exposure of bacteria in the environment to antibiotics from anthropogenic sources may lead to an increase in antibiotic resistance above natural levels, both total and antibiotic resistant E. coli will be enumerated. Samples will be collected upstream and downstream from point sources of treated wastewater effluent in two northwest Arkansas streams, Mud Creek and Spring Creek. Most probable numbers (MPN) will be determined for water and sediment bacteria in the presence and absence of antibiotics. We are including sediments as well as water samples in this experiment because sediments may serve as a reservoir for fecal indicator bacteria. In order to test for the possibility of multiple antibiotic resistance, water and sediment samples will be exposed to antibiotics of five different classes, including antibiotics not previously detected in the streams.

For indicators to function as intended and represent current contamination, there needs to be knowledge of what the background population levels are in local streams. Although the U.S. Environmental Protection Agency and the Arkansas Department of Environmental Quality have made recommendations and have standards in place, there is some controversy over the appropriate indicator species in different regions, with some states reconsidering the appropriate indicator species. Downstream states can impose water quality standards on upstream states. To be prepared to respond to potential downstream states’ concerns and to be armed with knowledge to make regulatory decisions, there needs to be local research determining the absolute and relative abundance of indicator organisms in streams in northwest Arkansas. Additionally, since there apparently are resident populations of indicator bacteria in the environment, it is important to know if indicators are increasing in antibiotic resistance.

Specific research objectives include:
Objective 1: To determine numbers of E. coli and Ent. faecalis in two AR streams upstream and downstream of wastewater treatment plants.
Objective 2: To determine antibiotic resistance of E.coli in the water and sediment for five different antibiotics.

This research will help improve understanding of the occurrence, distribution, and acquisition of antibiotic resistance of bacterial indicators of fecal contamination. This information is essential for effective microbial source tracking and identification of public health risk. For example, if indicator bacteria have substantial resident populations and those populations are acquiring resistance to antibiotics in the environment because of low levels of antibiotics being introduced with treated wastewater effluent, the basis of using antibiotic resistance analysis to identify sources of fecal contamination may be invalidated.

Progress/Completion Report, PDF