Progress 10/01/13 to 09/30/14
Outputs
Target Audience:
Nothing Reported
Changes/Problems:
Nothing Reported
What opportunities for training and professional development has the project provided?
Nothing Reported
How have the results been disseminated to communities of interest?
Nothing Reported
What do you plan to do during the next reporting period to accomplish the goals?
Nothing Reported
Impacts
What was accomplished under these goals?
Nothing to report.
Publications
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Progress 10/01/12 to 09/30/13
Outputs
Target Audience:
Nothing Reported
Changes/Problems:
Nothing Reported
What opportunities for training and professional development has the project provided?
Nothing Reported
How have the results been disseminated to communities of interest?
Nothing Reported
What do you plan to do during the next reporting period to accomplish the goals?
Nothing Reported
Impacts
What was accomplished under these goals?
Especially interesting at one of the study sites, noE. coliO157 was found in the surface water or sediment despite the fact that the study area has one of the highest concentrations of cattle in the United States and cattle are the main reservoir of pathogenicE. coli. However,the presence of antibiotic resistant non pathogenicE. coliin this watershed is significant because of possible horizontal gene transfer from generic to pathogenicE. coliwhich may lead to increased duration and severity of morbidity.
Publications
- Type:
Journal Articles
Status:
Published
Year Published:
2012
Citation:
Ibekwe, A.M., M. B. Leddy, R.M. Bold and A.K. Graves. 2012. Bacterial community composition in low-flowing river water with different sources of pollutants. FEMS Microbiol. Ecol. 79:155166.
- Type:
Journal Articles
Status:
Published
Year Published:
2012
Citation:
Duckworth, O., D. Osmond, A.K. Graves, M. Burchell and L. Wu. 2012. Relationships between nitrogen transformation rates and gene abundance in riparian buffer soil. Environ. Management. 50(5):861-874.
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Progress 10/01/11 to 09/30/12
Outputs
OUTPUTS: Microbial source tracking and fate/transport research conducted during this project have been disseminated to the scientific community through journal publications listed below, presentations at the 2012 Land Grant/Sea Grant National Water Conference, and the 2012 American Society for Microbiology General Meeting. PARTICIPANTS: Nothing significant to report during this reporting period. TARGET AUDIENCES: Provides information for use by other scientists, state and local policymakers, students, and special interest groups. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.
Impacts
The research described in this project provides new knowledge that will allow sources of bacteria in waterways to be assessed and characterized with a greater degree of certainty. As result, concerns about microbial water quality can be more accurately addressed.
Publications
- Stall, C., A. Amoozegar, D. Lindbo, A.K. Graves, and D. Rashash. 2012. Transport of E. coli in a sandy soil as impacted by depth of water table. J. Environ. Health. Accepted, October 11, 2012.
- Duckworth, O., D. Osmond, A.K. Graves, M. Burchell and L. Wu. 2012. Relationships between nitrogen transformation rates and gene abundance in riparian buffer soil. Environ. Management. 50(5):861-74.
- Ibekwe, A.M., M. B. Leddy, R.M. Bold and A.K. Graves. 2012. Bacterial community composition in low-flowing river water with different sources of pollutants. FEMS Microbiol. Ecol. 79:155-166.
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Progress 10/01/10 to 09/30/11
Outputs
OUTPUTS: Outreach activities involved presenting information to program participants at organizational meetings and training workshops. For example, on November 4, 2011, I presented "Fecal TMDL: Pathogen Indicators, Present and Future" to the Municipal Association of South Carolina (MASC): South Carolina Association of Stormwater Managers (SCASM) during their Fourth Quarter Meeting in Columbia, SC. I also presented "Using Harvested Rainwater-Real vs. Perceived Health Risks" to participants of the Rainwater Harvesting Workshop - 2011: Moving our Communities toward More Sustainable Water Use. This event was sponsored by the NC Coastal Training Program and NC Cooperative Extension on October 18, 2011 in Jacksonville, NC. Copies of presentation materials were distributed to the participants on site during the meeting. PARTICIPANTS: Mark Ibekwe, a microbiologist with the USDA Agricultural Research Service has collaborated in efforts to determine the relationships between manure management, populations of human pathogens and antibiotic resistant bacteria in soil and water environments. TARGET AUDIENCES: Nothing significant to report during this reporting period. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.
Impacts
Host source identification is the first step in assessing risk and mitigation strategies associated with microbial contamination in agricultural or urban settings. On May 11, 2011 the Environmental Protection Agency (EPA) approved a TMDL for Oyster Creek in Hyde County, NC. This TMDL was based on the data generated from a project that I served as lead PI, "Identifying Sources of Fecal Contamination and TMDL Development in the Swanquarter Bay". This project was funded by the NC Division of Water Quality (DENR), Environmental Protection Agency (EPA). Results published in "Microbial source tracking in a watershed dominated by swine" show that we must consider wildlife as potential transporters of bacteria from lagoons and the potential microbial impacts from other farms located in the watershed. Furthermore, detecting antibiotic resistant bacteria from our environment raises public health concerns because of increased reports of illness and deaths associated with infections due to antibiotic resistant bacteria. Results from my research program have increased awareness of the widespread occurrence of antibiotic resistance in agricultural systems within confined swine farms; a description has been published in my paper, "Distribution of ten antibiotic resistance genes in E. coli isolates from swine manure, lagoon effluent and soil collected from a lagoon waste application field". Similarly, the occurrence of antibiotic resistance in environmental pools associated with urban settings is widespread as well, and is described in a paper that I co-authored, "Genetic diversity and antimicrobial resistance of E. coli from human and animal sources uncovers multiple resistances from human sources".
Publications
- Ibekwe,A.M., S.E. Murinda and A.K. Graves. 2011. Genetic diversity and antimicrobial resistance of E. coli from human and animal sources uncovers multiple resistances from human sources. PLoS ONE 6(6): e20819. doi:10.1371/journal.pone.0020819. http://alturl.com/85odt
- Graves, A.K., L. Liwimbi, D.W. Israel, E. van Heugten, B. Robinson, C.W. Cahoon and J.F. Lubbers. 2011. Distribution of ten antibiotic resistance genes in E. coli isolates from swine manure, lagoon effluent and soil collected from a lagoon waste application field. Folia Microbiol. 56:131-137.
- Hathaway, J.M., W.F. Hunt, A.K. Graves, K.L. Bass and A.E. Caldwell. 2011. Exploring fecal indicator bacteria in a constructed stormwater wetland. Water Sci. Technol. 63(11): 2707-2712.
- Graves, A.K. and C. Hagedorn. 2010. Identifying sources of fecal pollution in water with antibiotic resistance patterns. Environ. Res. J. 5(6): 749-774.
- Graves, A.K. 2011. Food safety and implications for microbial source tracking. In C. Hagedorn, A. Blanch and V.J. Harwood (eds.), Microbial Source Tracking: Methods, Applications and Case Studies. pp. 585-607. New York, NY. Springer Publishers.
- Ibekwe, A.M., S.E. Murinda and A.K. Graves. 2011. Microbiological evaluation of water quality from urban watersheds for domestic water supply improvement. Int. J. Environ. Res. Public Health. 8: 4460-4476.
- Ibekwe, A.M., S.M. Lesch, R. M. Bold, M.B. Leddy and A.K. Graves. 2011. Variations of indicator bacteria in a large urban watershed. Transactions of the ASABE. 54(6): 2227-2236.
- Ibekwe, A.M., S.E. Murinda and A.K. Graves. 2011. Microbiological evaluation of water quality from urban watersheds for domestic water supply improvement. Int. J. Environ. Res. Public Health. 8: 4460-4476.
- Hathaway, J.M., W.F. Hunt, A.K. Graves and J.D. Wright. 2011. Field evaluation of bioretention indicator bacteria sequestration in Wilmington, NC. J. Environ. Engineering 137(12): 1103-1113.
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Progress 10/01/09 to 09/30/10
Outputs
OUTPUTS: Four MST methods (ARA, rep-PCR, optical brightener detection, and human specific Bacteroides HF183 marker detection) for identifying sources of fecal pollution were assessed in Oyster Creek, located in Hyde County, NC. This restricted shellfish harvesting area is impaired by levels of bacteria exceeding North Carolina's water quality standards for fecal coliform, which has resulted in closure of the waterbodies to shellfish harvesting. A variety of data at the watershed scale, including shoreline sanitary survey data and Geographic Information Systems (GIS) data coverage, were also used to identify potential fecal coliform contributions. There are no permitted point source facilities in the restricted shellfish area addressed in this report. Antibiotic resistance analysis was performed on 5,088 host-origin E. coli isolates and 10,368 E. coli isolates from 216 surface water samples. Host-origin isolates were collected throughout the study for library development. The application of stringent statistical measures for library development resulted in a final ARA library composed of 1,065 E. coli isolates with a 90% average rate of correct classification (ARCC). According to ARA, isolates identified as wildlife (54-96%) represented the predominant host source of E. coli. The 1,065 isolates used in the ARA library were subjected to repetitive element polymerase chain reaction (rep-PCR) as a means for cross validation of the ARA results. A subset of E. coli isolates (1,728) from the surface waters of Oyster Creek were evaluated by rep-PCR. Similar to the ARA method, rep-PCR implicated wildlife (57-100%) as the predominant host source E. coli isolates in Oyster Creek. Four MST methods (ARA, rep-PCR, optical brightener detection, and human specific Bacteroides HF183 marker detection) implicated a human contribution at eight of the 22 sampling stations. The combined Bayesian statistical method and finite difference transport modeling approaches was used to estimate fecal coliform load from watersheds and to develop TMDLs. The TMDLs developed for the restricted shellfish harvesting area of Oyster Creek for fecal coliform load are as follows: The fecal coliform TMDL = 2.3 X 10 ^11 counts per day. The load reduction needed to meet the shellfish criterion is 92.6%. The reduction established based on the 90th percentile criterion ensures that the water body will meet water quality standards 90% of the time. Management strategies to meet the proposed reduction will be implemented on a daily basis, to achieve the control of fecal loads for all but the most extreme 10% of events (i.e. ensure that 90% of the concentrations are at or below the 90th percentile criterion). These extreme events are often caused due to hydrologic variability, storm water management, change of land use practices, and change of wildlife activities during the previous ten year period. Source reductions can be assigned by first managing controllable sources (human, livestock, and pets) and then determining if the TMDL could be achieved. If the total required reduction was not achieved, then the wildlife source can be considered to be reduced. PARTICIPANTS: Jay Levine, Population Health and Pathobiology Department, North Carolina State University College of Veterinary Medicine: Jian Shen, Virginia Institute of Marine Science, College of William and Mary: Yuan Zhao, Virginia Institute of Marine Science, College of William and Mary. TARGET AUDIENCES: Nothing significant to report during this reporting period. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.
Impacts
Load allocations determined by modeling and fecal source identification determined by microbial source tracking provide the ability to develop realistic total maximum daily loadings (TMDLs) for fecal bacteria, and implementation of cost-effective best management practices (BMPs) for watershed restoration. Prior to the adoption of expensive infrastructure improvements to improve surface water quality; the sources of fecal pollution must be unequivocally identified. Unequivocal fecal source identification requires a combination of comprehensive site evaluation, intensive sampling, and accurate MST method(s). For microbial source tracking, the best evidence supports taking a multi-tiered toolbox approach of evaluating general to specific methods. ARA and rep-PCR results were not unexpected given the land use parameters of the watershed. Both library based methods indicated wildlife was the predominant source of E. coli in Oyster Creek. Evidence of human fecal contamination was found by two library-dependent, a library-independent and a chemical source tracking method. The wildlife contribution was greatest at sampling locations closest to the mouth of the stream. The human, livestock and pet contributions were greatest at sampling locations near drainage ditches and residential/business properties. Human, livestock and pet sources of fecal pollution can often minimized and/or eliminated as a contamination problem. Initial efforts to address potential human contributions to Oyster Creek may involve: 1) close monitoring of human waste discharge from boats that frequent the area; 2) determine if alternative on-site wastewater management systems, such as field application of waste are still being used in the watershed. Simple modifications in land application rates, time of application, etc. may be necessary; 3) determine if waste is properly managed at properties positioned along Oyster Creek. Livestock and pet sources of contamination can be addressed by simply keeping the animals out of the water. Additional measures also include the proper management of land applications of animal waste.
Publications
- J.P. Holt, E. van Heugten, A.K. Graves, M.T. See, W.E.M. Morrow. 2010. Growth performance and antibiotic tolerance patterns of nursery and finishing pigs fed growth-promoting levels of antibiotics. Livestock Science. Accepted: 9/8/2010.
- Lloyd Liwimbi, Alexandria K. Graves, Daniel W. Israel, Eric van Heugten, Bradford Robinson, Charles W. Cahoon and Joice F. Lubbers. 2010. Microbial Source Tracking in a Watershed Dominated by Swine. WATER (3), 587-604.
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Progress 10/01/08 to 09/30/09
Outputs
OUTPUTS: Three source tracking methods for identifying sources of fecal pollution were assessed in a segment of the North River, Carteret County, North Carolina. In all, 306 water samples were collected from 34 stream sites (representing estuary, mixing and tidal drainage ditch locations) and the abundance of fecal indicator bacteria exceeded regulatory standards for designated recreational waters in all samples. Antibiotic resistance analysis was performed on 14,688 E. coli isolates from the 306 water samples and 4,320 E. coli isolates from 90 sediment samples. Overall, 47% of the 6,480 E. coli isolates from water collected from estuary and mixing locations (combined) were identified as human origin, while 61% of the 1,584 E. coli isolates from those sediments were identified as human origin. On average, 48% of the 8,208 E. coli isolates from water collected from tidal ditch locations were identified as human origin, while 51% of the 2,736 E. coli isolates from the ditch sediments were identified as human. Water samples (n=120) were evaluated by fluorometry for optical brighteners (OBs). On average, 30 of the 34 sampling locations were positive for OBs with ≥100 fluorometric units (FU) before UV light exposure. After 4 hours of UV exposure, 26 of the 30 sampling locations were confirmed as positive for OBs with a ≥ 30% relative decrease in FU. Water samples (n=120) were assayed by PCR analysis for the human-specific Bacteroides HF183 marker. The HF183 marker was detected in five samples. The low incidences of the human marker were surprising given the ARA and OB data suggested a significant human contribution. However, the low incidences may be explained by PCR inhibition. The results from this study suggest a chronic, persistent allocation of isolates of human origin. The high human source identifications of E. coli in sediment samples suggest that sediments are a reservoir of these organisms and may contribute to the findings in the water column. On a swine farm in Sampson County, NC, Escherichia coli isolates were recovered from swine manure and water samples by basic microbiological culture and IDEXX Colilert methods, respectively. Antibiotic resistance genes were identified from the isolates using the polymerase chain reaction (PCR) method. On average, E.coli counts in the surface water were 272.1 CFU/100 mL, 10 fold higher than that in ground water (21.1 CFU/100 mL). A total of 1,208 E. coli isolates from swine feces, lagoon effluent, cattle, deer, dog, bird and nearby ground and surface waters (n=238, 234, 192, 48, 48, 48, 200, and 200, respectively) were evaluated for ARGs. A total of 5909 E. coli isolates were evaluated for phenotypic expression of resistance to various concentrations of eight antibiotics. Genotypic evaluation indicated the presence of aadA, strA, strB, tetA, tetB, tetC, sul1, sul2, sul3, and Aac(3)IV ARGs in all the sources of isolates. The database developed from antibiotic resistance patterns (ARP) and antibiotic resistant genes (ARGs) of E. coli isolates from the known sources were able to associate fecal bacteria in ground and surface water to lagoon effluent, livestock and wildlife. PARTICIPANTS: Dr. Daniel Israel, Participant in evaluation of swine lagoon effluent. NC WRRI, financial support for swine lagoon effluent study. Dr. David Lindbo, Participant in North River Study. Z. Smith Reynolds Foundation, financial support for North River Study. TARGET AUDIENCES: Not relevant to this project. PROJECT MODIFICATIONS: Not relevant to this project.
Impacts
The application of multiple source tracking methods increased confidence in results for the detection of human-origin pollution in the North River study. When sources of fecal contamination are identified, potential problem areas can be located, allowing the next step of developing management strategies to reduce or eliminate the sources. The results from the Sampson County study will increase awareness on the widespread of antibiotic resistance in both agricultural systems and environmental pools within confined swine farms. Even though good management practices for swine waste management (anaerobic lagoon systems) are effectively mitigating fecal pollution, there is a need for prudent and responsible use of antibiotics especially with those prone to induce resistance.
Publications
- Graves, A.K. and C. Hagedorn. 2009. Identifying Sources of Fecal Pollution in Water with Antibiotic Resistance Patterns. Environ. Res. J. Accepted for publication.
- Graves, A.K. and R.W. Weaver. 2009. Characterization of Enterococci Populations Collected from a Subsurface Flow Constructed Wetland. J. Appli. Microbiol. In press DOI: 10.1111/j.1365-2672.2009.04516.x
- Graves, A.K. and C. Hagedorn. 2009. Antibiotic Resistance as a Method for Determining Sources of Fecal Pollution in Water. In Frank Columbus (ed.) Antibiotic Resistance. Nova Science Publishers, Inc. Hauppauge, NY. In press. ISBN: 978-1-60741-623-4.
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Progress 10/01/07 to 09/30/08
Outputs
OUTPUTS: The use of antibiotics in animals is suspected to be a major route for transfer of antibiotic resistance genes (ARGs) to human pathogens, although different antibiotics are used in animals than in humans. North Carolina has the second largest swine production industry in the USA which is concentrated in a small geographical area in the southeastern part. This may increase the risk of antibiotic resistant bacteria reaching nearby surface waters. The goal of this year's work was to identify and quantify ARGs in Escherichia coli isolates from swine feces, lagoon effluent, and ground and surface waters from a commercial swine facility. Escherichia coli isolates were recovered from manure and water samples by basic microbiological culture and IDEXX Colilert methods, respectively. Antibiotic resistance genes were identified from the isolates using the polymerase chain reaction (PCR) method. A total of 848 E. coli isolates from swine feces, lagoon effluent, and nearby ground and surface waters (n=238, 234, 193, and 183, respectively) were recovered. All the E. coli isolates were evaluated for phenotypic expression of resistance to various concentrations of the following antibiotics: erythromycin, neomycin, oxytetracycline, streptomycin, tetracycline, cephalothin, apramycin, trimethoprim, and rifampicin. All the isolates displayed multiple antibiotic resistances. Genotypic evaluation indicated the presence of aadA, strA, strB, tetA, tetB, tetC, sul1, sul2, sul3, and aac(3)IV ARGs in all the sources of isolates. The number of ARGs in E. coli isolated from swine feces and lagoon effluent were not significantly different, while those from lagoon effluent were significantly (p≤0.05) fewer than from ground and surface water. The host source of the E. coli recovered from ground and surface waters will be identified by the microbial source tracking method, antibiotic resistance analysis (ARA) and related to the lagoon effluent application onto nearby fields. If the source proves to be lagoon effluent, this would support the need for improved mitigation strategies. In an effort to evaluate the targeted sampling approach to identifying sources of fecal pollution in surface water, a study was conducted on the North River, Carteret County, NC. The community along the North River developed on soils that are not suitable for conventional on-site systems, thus these systems may be a potential source of fecal coliforms in the North River. Surface water was collected monthly for a period of nine months. Well water sampling occurred 4 times over the duration of the study. Over 20,000 E. coli isolates from the North River have been evaluated by antibiotic resistance analysis. The data analyzed to date suggest that human and wildlife are the predominant source of fecal pollution. PARTICIPANTS: Dr. Daniel Israel, Participant in evaluation of swine lagoon effluent. NC WRRI, financial support for swine lagoon effluent study. Dr. David Lindbo, Participant in North River Study. Z. Smith Reynolds Foundation, financial support for North River Study. TARGET AUDIENCES: Not relevant to this project. PROJECT MODIFICATIONS: Not relevant to this project.
Impacts
The results of this research will provide important information regarding the role of land application of lagoon effluent in spreading of antibiotic resistance genes to surface waters. Early diagnosis of the problem will allow for the development of improved technologies and mitigation strategies for land applications of waste. Additionally, the microbial source tracking efforts conducted in the North River Community will provide the data and/or supportive documentation that on-site wastewater systems are contributing to bacterial loading in the North River. This data will be available for subsequent grant proposals to acquire funds for a more suitable wastewater management plan for the community.
Publications
- No publications reported this period
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Progress 10/01/06 to 09/30/07
Outputs
The E. coli and Enterococcus isolates previously evaluated by antibiotic reistance analysis have also been evaluated by PCR based on the 16S-23S rDNA Intergenic Spacer Region of Enteric Bacteria. Ribosomal DNA (rDNA) are sequences encoding ribosomal RNA (rRNA). The rRNA genetic locus, rrn, is sufficiently conservative and can be used in a universal organization of evolutionary relationships. PCR analysis of the 16S-23S rDNA intergenic spacer region (ISR) has been used to evaluate E. coli and Enterococcus isolates and is emerging as a tool in microbial source tracking research. The banding patterns of isolates from different sample sources were similar, but not always identical. Molecular weight of each band was analyzed and the percentages of isolates having bands at specific molecular weight regions were recorded The molecular weight was divided into 16 regions, 50 bp increments from 100 bp fragments to 800 bp fragments. This was done because there were very few bands
smaller than 100 bp and larger than 800 bp, and most 50 bp regions within 100 to 800 bp had only one band within them. Band lengths were quantified and converted to binary data in each region. Discriminant analysis of the binary PCR data generated from the analysis of E. coli revealed considerable similarities among banding patterns from the four sources (swine nursery feces, swine nursery lagoon liquid, swine finishing feces, and swine finishing lagoon liquid). The percentage of isolates which was correctly classified as finishing feces was high, 89%. But the percentages of the other three sources were low, all less than 70%. However, the results of classification of isolates by broad categories of nursery and finishing source categories were better with a correct classification rate greater than 75%. Discriminant analysis of the binary PCR data generated from the analysis of Enterococcus also revealed considerable overlap among sources. The percentage of correct classification for
nursery feces was large, close to 90%; the percentages of correct classification for other three sources were low, especially for the finishing lagoon, which was only 38.67%. The percentages of correct classification became larger if combine feces and lagoon together as broad source categories, which were > 80% for both nursery and finishing source category. The isolates evaluated by PCR are currently being evaluated for the presence of antibiotic resistance genes and virulence genes.
Impacts
Even though source tracking research was not conducted in this study, analyzing the PCR data by means of the discriminant analysis method can give us a clear picture of how much overlap is between different source categories. In addition, this method can help us to determine what data is valuable to add to the bacterial source tracking database for fecal source identification of bacteria recovered from environmental waters.
Publications
- Graves, A.K., C. Hagedorn, A. Brooks, R.L. Hagedorn and E. Martin. 2007. Microbial source tracking in a rural watershed dominated by cattle. Water Research, 41(16): 3729-3739.
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Progress 10/01/05 to 09/30/06
Outputs
Manure, lagoon and soil samples have been collected from swine nursery and finishing facilities. There were two sampling events, one in December 2005 and the other in July 2006 to represent a cool and warm season, respectively. The objectives are 1) to determine the effects of lagoon treatment on the persistence of antibiotic resistance in enteric bacteria; 2) to determine if there are genetic differences among the enteric bacteria and how it relates to the persistence of antibiotic resistance and 3) to determine if there is a seasonal variation of antibiotic resistance in enteric bacteria. Interestingly, neither E. coli nor Enterococcus was isolated from soil samples. Isolates analyzed for antibiotic resistance were collected from 13 samples in total (3 nursery manure samples, 3 nursery lagoon liquid samples, 4 finishing manure samples, and 3 finishing lagoon liquid samples). Each manure sample represents a composite sample of manure collected from a number of swine
in a particular swine house. For example, 3 nursery manure samples refers to 3 different swine houses at the nursery facility and each house represents a different stage of development (age) of swine. For each sample, 192 E. coli isolates and 192 Enterococcus isolates were collected for a total of 2496 E. coli isolates and 2496 Enterococcus isolates. The antibiotic treatments included those that have been commonly reported in microbial source tracking studies. These antibiotics include Amoxicillin, Cephalothin, Chlortetracycline, Erythromycin, Neomycin, Oxytetracycline, Streptomycin, Tetracycline, Rifampicin, and Vancomycin. E .coli and Enterococcus isolates displayed multiple antibiotic resistances in all the manure and lagoon samples. Isolates displayed different antibiotic resistance patterns for manure samples collected from different swine houses. For nursery facility samples, there were lower percent of isolates that showed antibiotic resistance in lagoons than in the manure.
For finishing facility samples, no such trend was apparent. For both E. coli and Enterococcus, percentages of resistant isolates were higher in nursery manure than in finishing manure. The resistance patterns were similar for the antibiotics which are in the same family. The percent of isolates resistant to tetracycline family were higher than other antibiotics. Three hundred isolates have been randomly selected for molecular evaluation using repetitive element polymerase chain reaction. Future work will involve data analysis to determine whether there is a relationship between the phenotypic and genotypic patterns of resistance. Additionally, the data will be evaluated to determine if there is a seasonal impact on resistance.
Impacts
Because land application of animal waste is a common fertilization practice, transfer of resistance to indigenous microorganisms could produce a significant reservoir facilitating the spread of resistance across ecosystems. If the bacteria in waste material readily transfer antibiotic resistance to environmental bacteria, our results may shed some light on the fate and transport of antibiotic resistance genes to our ground and surface waters.
Publications
- Graves, A.K., R.W. Weaver and J.A. Entry. Characterization of Enterococci Populations in Livestock Manure using BIOLOG. Accepted for publication, 2006. Microbiological Research. Ms. Ref. No.: MICRES-D-06-00240R1.
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Progress 10/01/04 to 09/30/05
Outputs
Manure and lagoon samples have been collected from a swine nursery and finishing facilities. In addition, soil samples have been collected from the spray fields at each facility. Enterococcus and Escherichia coli isolates have been isolated from the manure and lagoon samples. All isolates will be evaluated using antibiotic resistance analysis. The phylogenic diversity of the antibiotic resistant bacteria isolated from manure, lagoon, and soil samples will be determined using amplified ribosomal DNA restriction analysis. Additionally, microorganisms that are indigenous to the soil will be evaluated for antibiotic resistance to antibiotics that are commonly used in the swine industry.
Impacts
Because land application of animal waste is a common fertilization practice, transfer of resistance to indigenous microorganisms could produce a significant reservoir facilitating the spread of resistance across ecosystems. If the bacteria in waste material readily transfer antibiotic resistance to environmental bacteria, our results may shed some light on the fate and transport of antibiotic resistance genes to our ground and surface waters.
Publications
- R.W. Weaver, J.A. Entry, and Alexandria Graves. 2005. Numbers of fecal streptococci and Escherichia coli in fresh and dry cattle, horse, and sheep manure. Can. J. Microbiol. 51(10): 847-851.
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