Progress 09/01/03 to 08/31/08
Outputs
OUTPUTS: Our 3-year longitudinal study sampling scheme ended in February 2007. The funded project ended in 2008. We have completed phenotypic and genotypic analyses of E. coli, Enterococcus, Salmonella and Clostridium difficile. We have developed and shared new methods of statistical analysis of resistance data, developed and shared novel approaches for quantifying resistance in complex matrices, and assessed risks to an integrated population of humans (swine workers and non-workers) from both occupational exposure to swine and antibiotic use by both humans and swine. Five graduate students (2 MS, 3 PhD), one post-doctoral fellow, and 7 undergraduate/DVM students have been trained through this project. Our targeted audiences include food safety specialists in government and academia, agricultural and pharmaceutical private sectors, human health fields (publlic health). We have presented our findings to local, state, national and international audiences. The PI has been asked to serve on several international panels as a result of tthis effoort (European Union in 2007 and 2008; World Health organization in 2009). Federal agencies including FDA, USDA and CDC remain very interested in our work and approaches to assessing the data arising longitudinally from this unique integrated community. PARTICIPANTS: PARTICIPANTS: Individuals (all Texas A&M University unless otherwise noted): PI: H. Morgan Scott DVM, PhD Co-PIs: Roger B. Harvey DVM, MS; Robin Anderson PhD; Ken Bischoff, PhD (all USDA-ARS) Collaborators: D. Bruce Lawhorn, DVM, MS; Bo Norby, C. Med Vet, MPVM, PhD; Suresh Pillai, PhD; Dan Posey DVM; Lewis Dinges DVM; Derry Magee DVM; Graham Medley PhD; Chris O'Callaghan DVM, PhD MS Graduate Students: Kristi Christian, Linda Campbell PhD Graduate Students: Walid Q. Alali, DVM, MS; Keri Norman BS; Neena Kanwar, DVM, MS. Post-doc: Walid Q. Alali DVM, MS, PhD TARGET AUDIENCES: TARGET AUDIENCES: Public health agencies: Centers for Disease Control and Prevention, American veterinary medical Association. FDA, Texas Department of State Health Services, Texas Department of Criminal Justice Agricultural agencies: USDA, Food Safety Research and Response Network International agencies: Med-Vet-Net (EU), EU-US Safefood Initiative Pharmaceutical companies. World health organization. Agricultural commodity groups (especially swine producers) Veterinarians: American Association of Swine Practitioners PROJECT MODIFICATIONS: We added an additional bacterium after the last year of sampling was ccompleted (in addition to E. coli, Enterococcus, and Salmonella). We have been assessing the stored samples for Clostrium difficile, funded in part by the National Pork Board through two grants to Drs. Roger Harvey and Morgan Scott (et al). In addition, we utilized PCR techniques in addition to the proposed phenotyping, but chose to use PFGE rather than ribotyping using the Qualicon system to better extend our expenditures. We have also begun to evaluate relative fitness of the stored strains of resistant bacteria, especially those harboring cephalosporin resistance as this has become a very important issue world wide with 3rrd and 4th generation products.
Impacts
Concurrent use of antimicrobials in both human and swine populations impacts levels of resistance among commensal E. coli: We examined the relationship between the prevalence of antibiotic-resistant (AR) commensal E. coli isolates from both human wastewater and composite swine fecal samples and the concurrent aggregated antibiotic use recorded within each host species in a multi-site vertically integrated swine and human populations. However, the effects of human therapeutic and swine subtherapeutic antibiotic use - though statistically significant (P < 0.05) on AR E. coli were moderate in this study. Occupational (agricultural worker exposure to swine) cohort impacts clusters of phenotypically assessed resistant strains of E. coli: In general, the adjusted odds-ratios of the multiple clusters (i.e., 14 clusters) for human isolates were significantly (P < 0.05) at a higher odds of being in the pansusceptible cluster (OR = 12.8) when compared to swine isolates. The adjusted odds-ratios of the multiple clusters for non-swine worker isolates were at significantly (P < 0.05) higher risk of being in the pansusceptible cluster (OR =13.6) compared to swine-worker isolates. In general, the adjusted odds-ratios of the multiple clusters for swine-worker E. coli isolates were significantly (P < 0.05) at higher odds of being in multi-resistant clusters (defined as resistant to ≥ 3 antimicrobial agents) as compared to non-swine worker isolates. Clostridium difficile in swine are more prevalent early in life, with greatly diminished prevalence near to slaughter. Resistance levels of strains from swine are less than from human counterparts (clinical cases reported in literature): Of 1008 swine fecal samples tested, 131 (13%) were positive for Cd. Nursing piglets had a prevalence of 36.5% compared to less than 10% for other age groups. Prevalence of Cd from human wastewater was 100/818 (12.2%). No differences in human isolation rates were noted on the basis of seasonality or for occupation (swine worker versus non-swine worker). We conclude that although piglets had a high prevalence of Cd, we believe that reduced carriage (3.9%) in grower/finisher swine may be a factor for decreased transmission risk for Cd in the food chain. Our Cd isolates appeared to have decreased antibiotic resistance compared to that reported for human clinical isolates.
Publications
- Norman KN, Scott HM, Harvey RB, Norby B, Hume ME, Andrews K. 2009. Proceedings of the 12th Conference of the International Society for Veterinary Epidemiology and Economics. Comparison of the prevalence and genotypic characteristics of Clostridium difficile isolated from various production groups in a vertically integrated swine operation.
- Beier, R.C., Duke, S.E., Ziprin, R.L., Harvey, R.B., Hume, M.E., Poole, T.L., Scott, H.M., Highfield, L.D., Alali, W.Q., Andrews, K., Anderson, R.C., and Nisbet, D.J. (2008). Antibiotic and disinfectant susceptibility profiles of vancomycin-resistant Enterococcus faecium (VRE) isolated from community wastewater in Texas. Bulletin of Environmental Contamination and Toxicology, 80, 188-194.
- Harvey, RB, Norman, KN, Scott, HM, Hume, ME, Andrews, K, Scanlan, 2008. CM. Survey of Clostridium difficile in retail meat and in mixed populations of swine and humans. Proceedings of Workshop: Exploring isolation of Clostridium difficile from meat. CDC, Atlanta, GA, Dec. 16, 2008.
- Harvey, RB. 2009. Clostridium difficile in cattle and swine. Invited presentation, American Society of Animal Science Annual Meeting, July 12-16, 2009, Montreal, Canada.
- Harvey, RB, Norman, KN, Hume, ME, Andrews, K, Scanlan, CM, McReynolds, JL, Scott, HM. 2009. Clostridium difficile in mixed populations of animals and humans. To be presented at the 26th International Congress of Chemotherapy and Infection, June 18-21, 2009, Toronto, Canada.
- NPB Interim Research Grant Report #2 submitted to the National Pork Board, Des Moines, IA, Dec. 3, 2008, entitled, "Epidemiological survey to determine the prevalence of Clostridium difficile in swine in an integrated swine operation (NPB #06-156)".
- Norman KN, Scott HM, Harvey RB, Norby B, Hume ME, Andrews K. 2009. Proceedings of the 12th Conference of the International Society for Veterinary Epidemiology and Economics Comparison of the prevalence and genotypic characteristics of Clostridium difficile in a closed and integrated human and swine population in Texas
- K.N. Norman, R.B. Harvey, H.M. Scott, M.E. Hume, K. Andrews, A.D. Brawley. 2009. Varied Prevalence of Clostridium difficile in an Integrated Swine Operation. Anaerobe. Under review.
- Alali W.Q., H.M. Scott, K.L. Christian, R.B. Harvey. 2009. Relationship between Level of Antimicrobial Use and Resistance among Escherichia coli Isolates from Integrated Multi-site Cohorts of Humans and Swine. Prev. Vet. Med. Under review.
- Alali W.Q., H.M. Scott, B. Norby. 2009. Assessing the dissimilarity of antimicrobial resistance phenotypes among fecal Escherichia coli isolated from two vocational cohorts of humans versus swine using cluster analysis and multivariate statistics. Prev. Vet. Med. Under review.
- Alali W.Q., H.M. Scott, B. Norby, W. Gebreyes, G.H. Loneragan. 2009. Quantification of the BlaCMY2 Resistance Gene in Feces from Beef Feedlot Cattle Administered Three Different Doses of Ceftiofur Crystalline-Free Acid in a Longitudinal Controlled Field Trial. Foodborne Path. Dis. 2009. Revision under review.
- Alali, W.Q., H.M. Scott, R.B. Harvey, Bo Norby, D.B. Lawhorn, S.D. Pillai. 2008. Longitudinal Study of Antimicrobial Resistance among Escherichia coli Isolates from Integrated Multi-site Cohorts of Humans and Swine. Appl. Environ. Microbiol. 74, 3672- 3681.
- Alali, W.Q., H.M. Scott, R.B. Harvey, Bo Norby, D.B. Lawhorn, S.D. Pillai. 2008. Longitudinal Study of Antimicrobial Resistance among Escherichia coli Isolated from Integrated Multi-site Cohorts of Humans and Swine. International Conference on Emerging Infectious Diseases, Atlanta, Georgia, March, 2008.
- H.M. Scott, Norby, B., Alali, W.Q.. 2008. Truth or consequences: the pitfalls and perils associated with ignoring the statistical and biological dependence inherent in multivariate antimicrobial resistance data. The 4th Med Vet Net Annual Meeting, St. Malo, France.
- Alali W.Q., H.M. Scott, B. Norby, W. Gebreyes, G.H. Loneragan. 2008. Quantification of BlaCMY2 resistance gene in feces from beef feedlot cattle administered 3 different doses of ceftiofur crystalline-free acid in a longitudinal controlled trial. The 4th Med Vet Net Annual Meeting, St. Malo, France.
- Scott H.M., Norby, B., Loneragan, G.H., Brashears, M.M., Harvey, R.B., 2008. Critical thresholds of resistance in enteric bacteria: modeling, monitoring and managing microbial ecology to protect antimicrobials of critical importance. 1st ASM Conference on Antimicrobial Resistance in Zoonotic Bacteria and Foodborne Pathogens, Copenhagen, Denmark.
- Harvey, RB, Norman, KN, Scott, HM, Hume, ME, Andrews, K. 2008. Prevalence of Clostridium difficile in an integrated swine operation. Proceeding of the 9th Biennial Congress of the Anaerobe Society of the Americas, p. 151. 2008.
- Alali W.Q., H.M. Scott, B. Norby. 2008. Assessing the dissimilarity of antimicrobial resistance phenotypes among fecal Escherichia coli isolated from two vocational cohorts of humans versus swine using cluster analysis and multivariate statistics. 1st ASM Conference on Antimicrobial Resistance in Zoonotic Bacteria and Foodborne Pathogens, Copenhagen, Denmark.
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Progress 01/01/07 to 12/31/07
Outputs
OUTPUTS: Our 3-year longitudinal study sampling scheme ended in February 2007. Since then, we have focused largely on the phenotypic analysis of resistance among E. coli isolated from both the human and swine populations. Genotypic analyses are now underway, and we have also expanded our investigations using the banked samples to include Salmonella and Clostridium difficile. We also have complied and begun analyses concerning the antibiotic usage in both the swine and human populations. These early results have been presented in an MS thesis. Our targeted audiences include food safety specialists in government and academia, agricultural and pharmaceutical private sectors, human health fields (publlic health). We have presented our findings to local, state, national and international audiences. In particular, following an invitation to participate in an EU-US Safefood Initiative Workshop on quantitative approaches to food safety (West Virginia, January 2007), and participating in the
Med-Vet-Net annual scientific meeting in Pisa, Italy (June 2007), the PI was invited to participate in another workshop on animal agriculture and antimicrobial resisstance (EU-US Safefood Initiative) in Segovia, Spain in October 2007. Federal agencies including FDA, USDA and CDC remain very interested in our work and approaches to assessing the data arising longitudinally from this unique integrated community.
PARTICIPANTS: Individuals (all Texas A&M University unless otherwise noted): PI: H. Morgan Scott DVM, PhD Co-PIs: Roger B. Harvey DVM, MS; Robin Anderson PhD; Ken Bischoff, PhD (all USDA-ARS) Collaborators: D. Bruce Lawhorn, DVM, MS; Bo Norby, C. Med Vet, MPVM, PhD; Suresh Pillai, PhD; Dan Posey DVM; Lewis Dinges DVM; Derry Magee DVM; Graham Medley PhD; Chris O'Calllaghan DVM, PhD MS Graduate Students: Kristi Christian, Linda Campbell PhD Graaduate Students: Walid Q. Alali, DVM, MS Post-doc: walid Q. Alali DVM, MS, PhD
TARGET AUDIENCES: Public health agencies: CDC, FDA, Texas Department of State Health Services, Texas Department of Criminal Justice Agricultural agencies: USDA, Food Safety Research and Response Network International agencies: Med-Vet-Net (EU), EU-US Safefood Initiative Pharmaceutical companies Agricultural commodity groups (especially swine producers) Veterinarians: American Association of Swine Practitioners
Impacts
The emergence, propagation, accumulation, and maintenance of strains of antimicrobial-resistant (AR) pathogenic bacteria have become a world wide health concern in human and veterinary medicine. The intensive therapeutic use and misuse of antimicrobial agents in human medicine and companion animals, as well as the therapeutic, prophylactic, and subtherapeutic use for growth promotion in food animals have substantially increased selective pressures on both pathogenic and commensal bacteria; thus favoring the propagation, accumulation and maintenance of AR bacteria. Many authors have attempted to link antimicrobial use in food animal agriculture with an increased risk of AR bacteria in humans. These authors have speculated that AR bacteria in animals could transfer to human populations through direct contact (e.g., occupational exposure) and indirect contact with animals (e.g., consumption of contaminated food products of animal origin). However, those studies have
largely been based on historical data and cross-sectional studies lacking a temporal component to establish cause-effect relationships. In a three-year longitudinal study, we examined the relationship between the seasonal prevalence of antimicrobial-resistant (AR) E. coli isolated from human wastewater and swine fecal samples and the following risk factors: host species, production type (swine), vocation (human swine workers, non-workers, and slaughter-plant workers), and season in a multi-site housing, vertically integrated swine and human population representative of a closed agri-food system. Human and swine E. coli (N = 4048 and 3429, respectively) isolated from wastewater and fecal samples were tested for antimicrobial susceptibility using the SensititreTM broth microdilution system. There were significant (P < 0.05) differences in AR E. coli prevalence between: 1) host-species, with swine isolates at higher risk for resistance to tetracycline, kanamycin, ceftiofur, gentamicin,
streptomycin, chloramphenicol, sulfisoxazole, and ampicillin, 2) swine production group, with purchased boars, nursery piglets, and breeding boars isolates at a higher risk of resistance to streptomycin and tetracycline, and 3) vocation, with human swine worker cohorts isolates exhibiting lowered sulfisoxazole and cefoxitin prevalence compared to non-worker cohorts, while slaughter-plant worker cohorts isolates exhibited elevated cefoxitin prevalence compared to non-workers. While high variability among seasonal samples over the 3-year period was observed, no significant temporal trends were apparent. There were significant differences in the prevalence of multi-drug resistance isolates between host species, with swine at higher risk than humans of carrying multi-drug resistant strains. Considering vocation, slaughter-plant workers were at higher risk of exhibiting multi-drug resistance E. coli than non-workers; however, there were no significant differences in multi-drug resistance
isolate prevalence by swine production group.
Publications
- Vincent, V., Scott, H.M., Harvey, R.B., Alali, W.Q., and Hume, M.E. (2007). Novel surveillance of Salmonella enterica serotype Heidelberg epidemics in a closed community. Foodborne Pathogens and Disease, 4, 375-385.
- Alali, W.Q., Scott, H.M., Harvey, R.B., Norby, B.(2007) Changes in Phenotypic Patterns of Antimicrobial Resistance among Escherichia coli Isolated from Integrated Multi-site Housing and Worker Cohorts of Humans and Swine. 3rd Annual Scientific Meeting of Med-Vet-Net, Lucca, Italy (Abstract).
- Christian, K.L., Scott, H.M., Alali, W.Q., Fajt, V.R., Harvey, R.B., Lawhorn, D.B. (2007) Relationship between level of antibiotic use and antibiotic resistance among Escherichia coli isolated from swine in a multi-site integrated farm-to-plate system. 2007 Annual Conference on Antimicrobial Resistance, National Foundation for Infectious Diseases, Washington, DC.
- Scott, H.M. (2007) Elucidating the Relationship between Pre-harvest Pathogens and Human Disease. 94th Annual Meeting of International Association for Food Protection, Lake Buena Vista, FL. S13.
- Scott, H.M. (2007) Quantifying the contributions of host, location, management, and antibiotic usage on levels of antimicrobial resistance among integrated human and swine population. NRI Epidemiological Approaches to Food Safety Principal Investigator's Meeting (Electronic Proceedings available from USDA-CSREES). Washington, DC.
- Christian, K.L., Scott, H.M., Alali, W.Q., Fajt, V.R., Harvey, R.B., and Lawhorn, D.B. 2007. Relationship between the level of antimicrobial use and resistance among commensal Escherichia coli isolated in a 3-year longitudinal study of a multi-site integrated swine farm-to-plate system. Proceedings of the 88th Annual Meeting, Conference of Research Workers in Animal Diseases, Chicago, IL. No. 79.
- Alali, W.Q., Scott, H.M., Harvey, R.B., and Norby, B. 2007. Longitudinal Study of Antimicrobial Resistance among Escherichia coli Isolated from Integrated Multi-site Cohorts of Humans and Swine. Proceedings of the 88th Annual Meeting, Conference of Research Workers in Animal Diseases, Chicago, IL. No. 80.
- Christian, K.L. 2007. The relationship between the level of antibiotic use and resistance among enteric bacteria in a multi-site human and swine population. MS Thesis, 106 pp. Texas A&M University, College Station, TX.
- Alali, W.Q., 2007. Longitudinal study of antimicrobial resistance among Escherichia coli isolated from integrated multi-site cohorts of humans and swine. PhD Dissertation, 217 pp. Texas A&M University, College Station, TX.
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Progress 01/01/06 to 12/31/06
Outputs
Systematic monthly aggregate samples were collected from the study population for 3 years (January 2004 to January 2007). In this longitudinal study, 3818 human wastewater and 5699 swine aggregate samples were collected. Thus far, 1988 human and 3254 swine E.coli isolates have been tested for antimicrobial susceptibility using the Sensititre microbroth dilution system representing 1667 and 2829 human and swine samples, respectively. To assess the variability of number of different resistant phenotypes in the samples, 5 E.coli colonies were selected randomly from human and swine samples in one month (February, 2005). The mean number of different phenotypes for human and swine for that month were 2.2 and 2.0 (out of 5), respectively. 61% of the human E. coli isolates were pan-susceptible to a panel of 16 antimicrobials (NARMS gram negative), 20% were single resistant and 18% were resistant to 2 or more antimicrobials. 12% of the swine E. coli isolates were
pan-susceptible, 41% were single resistant and 46% were resistant to 2 or more antimicrobials. The relationship between tetracycline resistance prevalence and the aggregate factors (e.g., host species, production type swine), vocation (human), location, season, year) in the study was assessed using generalized linear model (GLM), binomial error distribution, logit link function, and adjusted for dependency within unit location/farms using generalized estimated equations (GEE) in STATA ver 9.2. Tetracycline was selected for the initial testing of the statistical modeling because of its high levels of variability when compared to other the antimicrobials on NARMS panel. For ordinal response (multi-drug resistant) data, the GLM model was constructed using a multinomial distribution and a cumulative logit link function that adjusted for dependency within unit location/farms whenever unit location was not the risk factor in question in SAS ver 9.3.
Impacts
There was a significant (p<0.05) difference in isolates between host-species with swine at higher risk to tetracycline prevalence than humans. Also, there was a significant (p<0.05) difference in isolates among the seasonal samples over the 3-year period with August 2005 and 2006 (summer months in Texas) at greater risk to tetracycline resistant across both host-species. Furthermore, there was a significant (p<0.05) difference in isolates among the seasonal samples collapsed over the 3-year period with August at greater risk to tetracycline resistant across host-species. Swine production group was significantly (p< 0.05) associated with tetracycline prevalence with purchased boars, nursery piglets, and breeding boars at higher risk of resistant. There was a significant (p< 0.05) association of human occupational/consumer cohort with fecal matter draining from agricultural workers housing at elevated tetracycline prevalence. There were significant (p< 0.05) differences
in multiple resistant isolates between host species with swine at higher risk to multi-drug resistant than humans across all levels of multi-resistance. Unit location was significantly (p< 0.05) associated with variable multiple resistant isolates. There was a significant (p<0.05) difference in multiple resistant isolates among the seasonal samples collapsed over the 3-year period with autumn at greater risk to multi-drug resistant across host-species. There was no significant (p> 0.05) association of human occupational/consumer cohort or swine production group with multi-drug resistance.
Publications
- Vincent VS, Scott HM, Harvey RB, Alali WQ, Hume ME (2006) Which came first : the chicken, the egg, or the food handler? Novel surveillance of Salmonella enterica serotype Heidelberg epidemics in a closed community. Proceedings of the 11th Symposium of the International Society for Veterinary Epidemiology and Economics, Cairns, Australia: ISVEE 11, 661.
- Alali WQ, Scott HM, Gold DL (2006) Identifying groups among binary and ordinal phenotypic antimicrobial resistance data using cluster analysis techniques. Proceedings of the 11th Symposium of the International Society for Veterinary Epidemiology and Economics, Cairns, Australia: ISVEE 11, 531.
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Progress 01/01/05 to 12/31/05
Outputs
This year marked the completion of second full year of sampling of swine and human wastewater. Efforts have followed in terms of cultivation and characterization of phenotypic resistance profiles of both E. coli and Enterococcus species. Several papers were published arising from these samples including the first known occurrence of Vancomycin resistant Enterococcus faecium in community-based samples from the human population with no samples ever showing VREs from swine. Efforts also continued to begin to assess the quantitative load of genotypic materials coding for gentamicin and ceftiofur resistance in both host populations using real-time PCR. Achieving standard curves for the real-time PCR that cover the entire range of sample dilutions is proving difficult.
Impacts
No Vancomycin-resistant Enterococcus faecium were found in swine populations. However, we have identified VRE among a non-hospital based community of humans at the group level (usually restricted to hospital-based populations in North America). We continue to see increased levels of phenotypic AR resistance among swine versus humans. Interestingly, integron presence versus AR gene content of the integrons by host species appears paradoxical (see Campbell et al, 2005). The potential to estimate the risk/rate of transmission of coliforms among hosts within an integrated population of animals and humans in a closed system remains, with focus now on unique phenotypes arising in the human and swine 'intake' facilities.
Publications
- Scott, H.M., Campbell, L.D., Harvey, R.B., Bischoff, K.M., Alali, W.Q., Barling, K.S., Anderson, R.C. (2005) Patterns of antimicrobial resistance among commensal Escherichia coli isolated from integrated multi-site housing and worker cohorts of humans and swine. Foodborne Pathogens and Disease, 2, 24-37.
- Poole, T.L., Hume, M.E., Campbell, L.D., Scott, H.M., Alali, W.Q., Harvey, R.B. (2005) Characterization of vancomycin-resistant Enterococcus faecium isolated from community wastewater within a semi-closed agri-food system. Antimicrobial Agents and Chemotherapy, 49, 4382-4385.
- Campbell, L.D., Scott, H.M., Bischoff, K.M., Anderson, R.C., Harvey, R.B.. (2005) Prevalence of Class 1 integrons and antimicrobial resistance gene cassettes among enteric bacteria found in multi-site group-level cohorts of humans and swine. Journal of Food Protection 68, 2693-2697.
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Progress 01/01/04 to 12/31/04
Outputs
Systematic monthly aggregate samples were collected from the study population for 12 months (January 2004 to December 2004). This sampling scheme will continue for up to 2 more years. In the first year of this longitudinal study, 1201 human fecal matter (via waste water) and 1774 swine fecal samples were collected. 82% (987) of the human and 53% (931) of the swine samples were microbiologically cultured for Escherichia coli and Enterococcus faecalis in the USDA laboratory. E. coli were isolated from 84% of the cultured samples and 35% for E.faecalis. These isolates were then tested for antimicrobial susceptibility using Sensititre system. 53% of the human E. coli isolates were pan susceptible, 26% were singly resistant and 21% were resistant to 2 or more antimicrobials on NARMS custom panel. Furthermore, 3% of human E. faecalis isolates were pan susceptible, 9% were singly resistant and 88% were resistant to 2 or more antimicrobials. Similar culture methods were
applied to the swine samples. E.coli were isolated from 92% from the swine cultured samples and 30% for E. faecalis. 12% of the swine E. coli isolates were pan susceptible, 37% were singly resistant and 51% were resistant to 2 or more antimicrobials. None of the swine E. faecalis isolates were pan susceptible, 1% were singly resistant and 99% were resistant to 2 or more antimicrobials. We have established methods in our laboratory to detect, quantify, and longitudinally track the dissemination of specific AMR genes [for instance; acc(6)-IV and acc(3)-aph(6)] in community DNA, between human and swine populations, using real-time PCR. Presentations: November 14-16, 2004, Conference of Research Workers in Animal Diseases (CRWAD), Chicago, IL, H. Morgan Scott, Antimicrobial Resistance among E. coli Isolated from Group Cohorts of Humans and Swine in Integrated Populations; Alali, W.Q., Temporal changes in phenotypic and genotypic patterns of antimicrobial resistance among Enterococcus
faecalis isolated from integrated multi-site housing and worker cohorts of humans and swine; Campbell, L.D., Prevalence of VRE and commensal E. coli bearing antimicrobial resistance gene cassettes on Class I integrons isolated from integrated group-level cohorts of humans and swine.
Impacts
Initial results indicate, in general, that swine were at higher risk for resistant bacteria than humans, with younger pigs being the highest when compared to grower-finisher, breeding barns, slaughter-plant pens. No significant difference was detected between swine workers and non-workers cohorts based on AMR phenotypes. Unique AMR phenotypes between and within human and swine cohorts will be traced over the coming 2 years to determine the transmission dynamic in the study population. Furthermore, quantification of AMR genes in community DNA is expected to indicate whether the resistance at the gene levels reflects what has been expressed phenotypically. Also, AMR gene quantification has a great potential to determine the changes in the amount of resistance in human and swine populations over the study period.
Publications
- H.M. Scott, Campbell, L.D. Harvey R.B., Bischoff K.M., Alali W.Q., Barling K.S., and Anderson R.C. (2005). Patterns of Antimicrobial Resistance among Commensal Escherichia coli Isolated from Integrated Multi-site Housing and Worker Cohorts of Humans and Swine. Foodborne Pathogens and Disease; 2(1): 24-37.
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Progress 01/01/03 to 12/31/03
Outputs
Data collection from an earlier pilot study being conducted in the study population was completed in Fall 2003. Background efforts for the present project began in September 2003 and included revising the sampling schedule and locations to more extensive sampling points within the multiple swine operations, adding sampling points (3x the number) for the human wastewater access points including some 'hospice ward' access points targetting areas where antimicrobials are used in the human population. Slaughterplant access points and a schedule for sampling of pork by-products is established. Mapping and permanent identifiers have been afixed to sampling points to ensure continuity and receiving processing protocols at the transfer lab and USDA laboratory. Systematic monthly sampling began in December 2003 / January 2004 and will continue for 3 years. Major supplies and equipment purchases have been made per the proposal and the laboratory is now completely equipped for
microbiological work including basic culture and isolation, Sensititre phenotypic evaluation of AMR, qualitative PCR, and ribotyping. In addition, we are pursuing developmental work within the laboratory in RT-PCR (in addition to qualitative PCR) for resistance genes in community DNA.
Impacts
Initial expected impact will be within 12 months as we process samples and determine the longitudinal patterns / changes in resistance within and between units. Results from the existing pilot project indicate a good range of disparate resistance patterns both within and among human/swine groupings for both E.coli and Enterococcus. This offers promising potential to detect transmission between species (should it occur) by either/direct contact (workers), environmenta, or foodborne exposure.
Publications
- No publications reported this period
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