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Christina Ahlstrom, Ph.D.

Christina is a Geneticist for the Alaska Science Center.

Professional Experience

  • 2017 - Present   Geneticist, USGS Alaska Science Center, Anchorage, Alaska

  • 2015 - 2017        Consultant Epidemiologist & Data Analyst, Epi-interactive, Wellington, New Zealand

  • 2017                    Molecular Epidemiology Consultant, Food and Agriculture Organisation, Rome, Italy

  • 2016                   Molecular Epidemiology Consultant, Food and Agriculture Organisation, Rome, Italy

  • 2005 - 2008     Seasonal Research Assistant, Quality Milk Production Services, Cornell University, Ithaca, NY

Education and Certifications

  • Ph.D.  2015    University of Calgary, Calgary, Alberta, Canada     Veterinary Medical Sciences

  • M.S.   2011    Colorado State University, Fort Collins, CO     Animal Science

  • B.S.   2008    University at Buffalo, Buffalo, NY     Biology

Science and Products

link
John Reed (USGS scientist) holding a gull marked with a satellite transmitter at the Soldotna landfill in June 2016

Antibiotic Resistant Bacteria in Migratory Birds

Migratory birds, and particularly those using habitats close to human settlements, may be infected with antibiotic resistant bacteria. The USGS is working with public health professionals to understand the role of birds in the maintenance and dispersal of antibiotic resistant bacteria. Additionally, the USGS is investigating how antibiotic resistant bacteria in birds may relate to public and...
By
Ecosystems, Wildlife Program, Alaska Science Center
link

Antibiotic Resistant Bacteria in Migratory Birds

Migratory birds, and particularly those using habitats close to human settlements, may be infected with antibiotic resistant bacteria. The USGS is working with public health professionals to understand the role of birds in the maintenance and dispersal of antibiotic resistant bacteria. Additionally, the USGS is investigating how antibiotic resistant bacteria in birds may relate to public and...
Learn More
link
Duck with various brown colored feathers

Avian Influenza Research

Since 2006, the USGS Alaska Science Center has been part of the State and Federal interagency team for the detection and response to highly pathogenic (HPAI) viruses in North America. Avian influenza or "bird flu" is a viral disease that primarily infects domestic poultry and wild birds. Avian influenza viruses are naturally occurring in wild birds such as ducks, geese, swans, and gulls. These...
By
Ecosystems, Wildlife Program, Alaska Science Center
link

Avian Influenza Research

Since 2006, the USGS Alaska Science Center has been part of the State and Federal interagency team for the detection and response to highly pathogenic (HPAI) viruses in North America. Avian influenza or "bird flu" is a viral disease that primarily infects domestic poultry and wild birds. Avian influenza viruses are naturally occurring in wild birds such as ducks, geese, swans, and gulls. These...
Learn More

Tracking Data for Three Large-bodied Gull Species and Hybrids (Larus spp.)

This metadata document describes the data contained in the "processedData" folder of this data package. This data package contains all data collected by the Argos System from 6 satellite transmitters attached to Glaucous-winged gulls on Middleton Island and 42 Argos-linked GPS satellite transmitters attached to three species of large-bodied gulls (genus Larus) and hybrids thereof
By
Alaska Science Center

Data for Continental-Scale Dispersal of Antimicrobial Resistant Bacteria by Alaska Landfill-Foraging Gulls

This data set includes information on collections of fecal samples from wild gulls (Larus spp.) at seven locations in Alaska, USA. Samples were screened for Escherichia coli (E. coli) and tested for resistance to multiple antibiotics.
By
Alaska Science Center

Sampling, Antimicrobial Resistance Testing, and Genomic Typing of Carbapenemase Producing E. coli in Gulls (Larus spp.) in Alaska, 2016

This data set includes information on collections of fecal samples from wild gulls (Larus spp.) at seven locations in Alaska, USA. Samples were screened for carbapenemase producing Escherichia coli (E. coli) and tested for resistance to multiple antibiotics.
By
Alaska Science Center

Sampling, antimicrobial resistance testing, and genomic typing of E. coli in gulls (Larus spp.) on the Kenai Peninsula, Alaska, 2016

This data set includes information on collections of fecal or cloacal samples from wild gulls (Larus spp.) at four locations on the Kenai Peninsula, Alaska, USA. Samples were also collected from sockeye salmon harvested as part of the personal-use fisheries on the Kenai and Kasilof Rivers. Samples were screened for Escherichia coli (E. coli) and tested for resistance to multiple antibiotics.
By
Alaska Science Center

Genomic comparison of carbapenem-resistant Enterobacteriaceae from humans and gulls in Alaska

ObjectivesWildlife may harbor clinically important antimicrobial resistant (AMR) bacteria, but the role of wildlife in the epidemiology of AMR bacterial infections in humans is largely unknown. In this study, we aimed to assess dissemination of theblaKPC carbapenemase gene among humans and gulls in Alaska.MethodsWe performed whole genome sequencing to determine the genetic context ofblaKPC in bact
By
Ecosystems, Alaska Science Center

Evidence for continental-scale dispersal of antimicrobial resistant bacteria by landfill-foraging gulls

Anthropogenic inputs into the environment may serve as sources of antimicrobial resistant bacteria and alter the ecology and population dynamics of synanthropic wild animals by providing supplemental forage. In this study, we used a combination of phenotypic and genomic approaches to characterize antimicrobial resistant indicator bacteria, animal telemetry to describe host movement patterns, and a
By
Ecosystems, Alaska Science Center

Comparative genomics and genomic epidemiology of mycobacterium avium subsp. paratuberculosis strains

Two phenotypically distinct strains of Mycobacterium avium subsp. paratuberculosis (MAP) were recognized in the 1930s but it was not until the introduction of restriction endonuclease analysis (REA) in the mid-1980s that these two strains, MAP-C and MAP-S, could be distinguished genetically. Since then, a plethora of molecular typing techniques has been applied to MAP isolates (reviewed by Li et a
By
Ecosystems, Alaska Science Center

Validation of a screening method for the detection of colistin-resistant E. coli containing mcr-1 in feral swine feces

A method was developed and validated for the detection of colistin-resistant Escherichia coli containing mcr-1 in the feces of feral swine. Following optimization of an enrichment method using EC broth supplemented with colistin (1 µg/mL) and vancomycin (8 µg/mL), aliquots derived from 100 feral swine fecal samples were spiked with of one of five different mcr-1 positive E. coli strains (between 1
By
Ecosystems, Alaska Science Center

Gulls as sources of environmental contamination by colistin-resistant bacteria

In 2015, the mcr-1 gene was discovered in Escherichia coli in domestic swine in China that conferred resistance to colistin, an antibiotic of last resort used in treating multi-drug resistant bacterial infections in humans. Since then, mcr-1 was found in other human and animal populations, including wild gulls. Because gulls could disseminate the mcr-1 gene, we conducted an experiment to assess wh
By
Ecosystems, Alaska Science Center

Antibiotic resistant bacteria in wildlife: Perspectives on trends, acquisitions and dissemination, data gaps, and future directions

The proliferation of antibiotic resistant bacteria in the environment has potential negative economic and health consequences. Thus, previous investigations have targeted wild animals to understand the occurrence of antibiotic resistance in diverse environmental sources. In this critical review and synthesis, we summarize important concepts learned through the sampling of wildlife for antibiotic
By
Ecosystems, Alaska Science Center

Early emergence of mcr-1-positive Enterobacteriaceae in gulls from Spain and Portugal

We tested extended‐spectrum β‐lactamase producing bacteria from wild gulls (Larusspp.) sampled in 2009 for the presence of mcr‐1. We report the detection of mcr‐1 and describe genome characteristics of four Escherichia coli and one Klebsiella pneumoniaeisolate from Spain and Portugal that also exhibited colistin resistance. Results represent the earliest evidence for colistin‐resistant bacteria in
By
Ecosystems, Alaska Science Center

Repeated detection of carbapenemase-producing Escherichia coli in gulls inhabiting Alaska, USA

We report the first detection of carbapenemase-producing Escherichia coli in Alaska and in wildlife in the United States. Wild bird (gull) feces sampled at three locations in Southcentral Alaska yielded isolates that harbored plasmid-encoded blaKPC-2 or chromosomally-encoded blaOXA-48, and genes associated with antimicrobial resistance to up to eight antibiotic classes.
By
Ecosystems, Alaska Science Center

Satellite tracking of gulls and genomic characterization of fecal bacteria reveals environmentally mediated acquisition and dispersal of antimicrobial resistant Escherichia coli on the Kenai Peninsula, Alaska

Gulls (Larus spp.) have frequently been reported to carry Escherichia coli exhibiting antimicrobial resistance (AMR E. coli); however, the pathways governing the acquisition and dispersal of such bacteria are not well-described. We equipped 17 landfill-foraging gulls with satellite transmitters and collected gull fecal samples longitudinally from four locations on the Kenai Peninsula, Alaska to as
By
Ecosystems, Alaska Science Center

Acquisition and dissemination of cephalosporin-resistant E. coli in migratory birds sampled at an Alaska landfill as inferred through genomic analysis

Antimicrobial resistance (AMR) in bacterial pathogens threatens global health, though the spread of AMR bacteria and AMR genes between humans, animals, and the environment is still largely unknown. Here, we investigated the role of wild birds in the epidemiology of AMR Escherichia coli. Using next-generation sequencing, we characterized cephalosporin-resistant E. coli cultured from sympatric gulls
By
Ecosystems, Contaminant Biology, Alaska Science Center

Pre-USGS Publications

Muellner, U., G. Fournie, P. Muellner, C. A. Ahlstrom, and D. U. Pfeiffer. 2018. Epidemix - an Interactive Multi-Model Application for Teaching and Visualizing Infectious Disease Transmission. Epidemics 23:49-54. doi:10.1016/j.epidem.2017.12.003.
Ahlstrom, C. A., P. Muellner, G. Lammers, M. Jones, S. Octavia, R. Lan, and J. Heller. 2017. Shiga-toxin producing E. coli O157 shedding dynamics in an Australian beef herd. Frontiers in Veterinary Science 4:200. doi:10.3389/fvets.2017.00200.
Ahlstrom, C. A., C. S. Manuel, H. C. Den Bakker, M. Wiedmann, and K. K. Nightingale. 2017. Molecular Ecology of Listeria spp., Salmonella, Escherichia coli O157:H7, and non-O157 Shiga Toxin Producing Escherichia coli in Pristine Natural Environments in Northern Colorado. Journal of Applied Microbiology. doi:10.1111/jam.13657.
Ahlstrom, C. A., P. Muellner, S. Spencer, S. Hong, A. Saupe, A. Rovira, C. Hedberg, A. Perez, and J. Alvarez. 2017. Inferring source attribution from a multi-year multi-source dataset of Salmonella in Minnesota. Zoonoses and Public Health 64(8):589-598. doi:10.1111/zph.12351.
Bauman, C. A., A. Jones-Bitton, C. A. Ahlstrom, L. Mutharia, J. De Buck, J. Jansen, D. F. Kelton, and P. Menzies. 2017. Identification of Mycobacterium avium ssp. paratuberculosis strains isolated from dairy goats and dairy sheep in Ontario, Canada. Canadian Journal of Veterinary Research 81(4):304-307.
Hong, S., A. Rovira, P. Davies, C. A. Ahlstrom, P. Muellner, A. Rendahl, K. Olsen, J. B. Bender, S. Wells, A. Perez, and J. Alvarez. 2016. Serotypes and antimicrobial resistance in Salmonella enterica recovered from clinical samples from cattle and swine in Minnesota, 2006 to 2015. International Journal of Parasitology: Parasites and Wildlife 11(12):e0168016. doi:10.1371/journal.pone.0168016.
Muellner, P., U. Muellner, M. C. Gates, T. Pearce, C. A. Ahlstrom, D. O'Neill, D. Brodbelt, and N. J. Cave. 2016. Evidence in Practice – A Pilot Study Leveraging Companion Animal and Equine Health Data from Primary Care Veterinary Clinics in New Zealand. Frontiers in Veterinary Science 3:116. doi:10.3389/fvets.2016.00116.
Davidson, F., C. A. Ahlstrom, J. De Buck, H. G. Whitney, and K. Tahlan. 2016. Examination of Mycobacterium avium subspecies paratuberculosis mixed genotype infections in dairy animals using a whole genome sequencing approach. PeerJ 4:e2793. doi:10.7717/peerj.2793.
Ahlstrom, C. A., H. W. Barkema, and J. De Buck. 2016. Relative frequency of 4 major strain types of Mycobacterium avium ssp. paratuberculosis in Canadian dairy herds using a novel single nucleotide polymorphism-based polymerase chain reaction. Journal of Dairy Science 99(10):8297-8303. doi:10.3168/jds.2016-11397.
Ahlstrom, C. A., H. W. Barkema, K. Stevenson, R. N. Zadoks, R. Biek, R. Kao, H. Trewby, D. Haupstein, D. F. Kelton, G. Fecteau, O. Labrecque, G. P. Keefe, S. L. B. McKenna, K. Tahlan, and J. De Buck. 2016. Genome-wide diversity and phylogeography of Mycobacterium avium subsp. paratuberculosis in Canadian dairy cattle. PLoS One 11:e0149017. doi:10.1371/journal.pone.0149017.
Ahlstrom, C. A., H. W. Barkema, K. Stevenson, R. N. Zadoks, R. Biek, R. Kao, H. Trewby, S. Hendrick, D. Haupstein, D. F. Kelton, G. Fecteau, O. Labrecque, G. P. Keefe, S. L. B. McKenna, and J. De Buck. 2015. Limitations of variable number of tandem repeat typing identified through whole genome sequencing of Mycobacterium avium subsp. paratuberculosis on a national and herd level. BMC Genomics 16:161. doi:10.1186/s12864-015-1387-6.
Den Bakker, H. C., S. Warchocki, E. M. Wright, A. F. Allred, C. A. Ahlstrom, C. S. Manuel, M. J. Stasiewicz, A. Burrell, S. Roof, L. Strawn, E. D. Fortes, K. K. Nightingale, D. Kephart, and M. Wiedmann. 2014. Listeria floridensis sp. nov., Listeria aquatica sp. nov., Listeria cornellensis sp. nov., Listeria riparia sp. nov., and Listeria grandensis sp. nov., from agricultural and natural environments. International Journal of Systematic and Evolutionary Microbiology 64:1882-1889. doi:10.1099/ijs.0.052720-0.
Ahlstrom, C. A., H. W. Barkema, and J. De Buck. 2014. Improved Short-Sequence-Repeat Genotyping of Mycobacterium avium subsp. paratuberculosis by Using Matrix-Assisted Laser Desorption Ionization—Time of Flight Mass Spectrometry. Applied and Environmental Microbiology 80:534-539. doi:10.1128/AEM.03212-13.
Zadoks, R. N., H. M. Griffiths, M. A. Munoz, C. A. Ahlstrom, G. J. Bennett, E. Thomas, and Y. H. Schukken. 2011. Sources of Klebsiella and Raoultella species on dairy farms: be careful where you walk. Journal of Dairy Science 94(2):1045-1051. doi:10.3168/jds.2010-3603.
Munoz, M. A., G. J. Bennett, C. A. Ahlstrom, H. M. Griffiths, Y. H. Schukken, and R. N. Zadoks. 2008. Cleanliness Scores as Indicator of Klebsiella Exposure in Dairy Cows. Journal of Dairy Science 91(10):3908-3916. doi:10.3168/jds.2008-1090.
Munoz, M. A., C. A. Ahlstrom, B. J. Rauch, and R. N. Zadoks. 2006. Fecal Shedding of Klebsiella pneumoniae by Dairy Cows. Journal of Dairy Science 89(9):3425-3430. doi:10.3168/jds.S0022-0302(06)72379-7.
Muellner, P., D. Hodges, C. A. Ahlstrom, M. Newman, R. Davidson, D. U. Pfeiffer, J. Marshall, and C. Morley. 2018. Creating a framework for the prioritization of biosecurity risks to the New Zealand dairy industry. Transboundary and Emerging Diseases 65(4):1067-1077. doi:10.1111/tbed.12848.

Science and Products

  • Science
    link
    John Reed (USGS scientist) holding a gull marked with a satellite transmitter at the Soldotna landfill in June 2016

    Antibiotic Resistant Bacteria in Migratory Birds

    Migratory birds, and particularly those using habitats close to human settlements, may be infected with antibiotic resistant bacteria. The USGS is working with public health professionals to understand the role of birds in the maintenance and dispersal of antibiotic resistant bacteria. Additionally, the USGS is investigating how antibiotic resistant bacteria in birds may relate to public and...
    By
    Ecosystems, Wildlife Program, Alaska Science Center
    link

    Antibiotic Resistant Bacteria in Migratory Birds

    Migratory birds, and particularly those using habitats close to human settlements, may be infected with antibiotic resistant bacteria. The USGS is working with public health professionals to understand the role of birds in the maintenance and dispersal of antibiotic resistant bacteria. Additionally, the USGS is investigating how antibiotic resistant bacteria in birds may relate to public and...
    Learn More
    link
    Duck with various brown colored feathers

    Avian Influenza Research

    Since 2006, the USGS Alaska Science Center has been part of the State and Federal interagency team for the detection and response to highly pathogenic (HPAI) viruses in North America. Avian influenza or "bird flu" is a viral disease that primarily infects domestic poultry and wild birds. Avian influenza viruses are naturally occurring in wild birds such as ducks, geese, swans, and gulls. These...
    By
    Ecosystems, Wildlife Program, Alaska Science Center
    link

    Avian Influenza Research

    Since 2006, the USGS Alaska Science Center has been part of the State and Federal interagency team for the detection and response to highly pathogenic (HPAI) viruses in North America. Avian influenza or "bird flu" is a viral disease that primarily infects domestic poultry and wild birds. Avian influenza viruses are naturally occurring in wild birds such as ducks, geese, swans, and gulls. These...
    Learn More
  • Data

    Tracking Data for Three Large-bodied Gull Species and Hybrids (Larus spp.)

    This metadata document describes the data contained in the "processedData" folder of this data package. This data package contains all data collected by the Argos System from 6 satellite transmitters attached to Glaucous-winged gulls on Middleton Island and 42 Argos-linked GPS satellite transmitters attached to three species of large-bodied gulls (genus Larus) and hybrids thereof
    By
    Alaska Science Center

    Data for Continental-Scale Dispersal of Antimicrobial Resistant Bacteria by Alaska Landfill-Foraging Gulls

    This data set includes information on collections of fecal samples from wild gulls (Larus spp.) at seven locations in Alaska, USA. Samples were screened for Escherichia coli (E. coli) and tested for resistance to multiple antibiotics.
    By
    Alaska Science Center

    Sampling, Antimicrobial Resistance Testing, and Genomic Typing of Carbapenemase Producing E. coli in Gulls (Larus spp.) in Alaska, 2016

    This data set includes information on collections of fecal samples from wild gulls (Larus spp.) at seven locations in Alaska, USA. Samples were screened for carbapenemase producing Escherichia coli (E. coli) and tested for resistance to multiple antibiotics.
    By
    Alaska Science Center

    Sampling, antimicrobial resistance testing, and genomic typing of E. coli in gulls (Larus spp.) on the Kenai Peninsula, Alaska, 2016

    This data set includes information on collections of fecal or cloacal samples from wild gulls (Larus spp.) at four locations on the Kenai Peninsula, Alaska, USA. Samples were also collected from sockeye salmon harvested as part of the personal-use fisheries on the Kenai and Kasilof Rivers. Samples were screened for Escherichia coli (E. coli) and tested for resistance to multiple antibiotics.
    By
    Alaska Science Center
  • Publications

    Genomic comparison of carbapenem-resistant Enterobacteriaceae from humans and gulls in Alaska

    ObjectivesWildlife may harbor clinically important antimicrobial resistant (AMR) bacteria, but the role of wildlife in the epidemiology of AMR bacterial infections in humans is largely unknown. In this study, we aimed to assess dissemination of theblaKPC carbapenemase gene among humans and gulls in Alaska.MethodsWe performed whole genome sequencing to determine the genetic context ofblaKPC in bact
    By
    Ecosystems, Alaska Science Center

    Evidence for continental-scale dispersal of antimicrobial resistant bacteria by landfill-foraging gulls

    Anthropogenic inputs into the environment may serve as sources of antimicrobial resistant bacteria and alter the ecology and population dynamics of synanthropic wild animals by providing supplemental forage. In this study, we used a combination of phenotypic and genomic approaches to characterize antimicrobial resistant indicator bacteria, animal telemetry to describe host movement patterns, and a
    By
    Ecosystems, Alaska Science Center

    Comparative genomics and genomic epidemiology of mycobacterium avium subsp. paratuberculosis strains

    Two phenotypically distinct strains of Mycobacterium avium subsp. paratuberculosis (MAP) were recognized in the 1930s but it was not until the introduction of restriction endonuclease analysis (REA) in the mid-1980s that these two strains, MAP-C and MAP-S, could be distinguished genetically. Since then, a plethora of molecular typing techniques has been applied to MAP isolates (reviewed by Li et a
    By
    Ecosystems, Alaska Science Center

    Validation of a screening method for the detection of colistin-resistant E. coli containing mcr-1 in feral swine feces

    A method was developed and validated for the detection of colistin-resistant Escherichia coli containing mcr-1 in the feces of feral swine. Following optimization of an enrichment method using EC broth supplemented with colistin (1 µg/mL) and vancomycin (8 µg/mL), aliquots derived from 100 feral swine fecal samples were spiked with of one of five different mcr-1 positive E. coli strains (between 1
    By
    Ecosystems, Alaska Science Center

    Gulls as sources of environmental contamination by colistin-resistant bacteria

    In 2015, the mcr-1 gene was discovered in Escherichia coli in domestic swine in China that conferred resistance to colistin, an antibiotic of last resort used in treating multi-drug resistant bacterial infections in humans. Since then, mcr-1 was found in other human and animal populations, including wild gulls. Because gulls could disseminate the mcr-1 gene, we conducted an experiment to assess wh
    By
    Ecosystems, Alaska Science Center

    Antibiotic resistant bacteria in wildlife: Perspectives on trends, acquisitions and dissemination, data gaps, and future directions

    The proliferation of antibiotic resistant bacteria in the environment has potential negative economic and health consequences. Thus, previous investigations have targeted wild animals to understand the occurrence of antibiotic resistance in diverse environmental sources. In this critical review and synthesis, we summarize important concepts learned through the sampling of wildlife for antibiotic
    By
    Ecosystems, Alaska Science Center

    Early emergence of mcr-1-positive Enterobacteriaceae in gulls from Spain and Portugal

    We tested extended‐spectrum β‐lactamase producing bacteria from wild gulls (Larusspp.) sampled in 2009 for the presence of mcr‐1. We report the detection of mcr‐1 and describe genome characteristics of four Escherichia coli and one Klebsiella pneumoniaeisolate from Spain and Portugal that also exhibited colistin resistance. Results represent the earliest evidence for colistin‐resistant bacteria in
    By
    Ecosystems, Alaska Science Center

    Repeated detection of carbapenemase-producing Escherichia coli in gulls inhabiting Alaska, USA

    We report the first detection of carbapenemase-producing Escherichia coli in Alaska and in wildlife in the United States. Wild bird (gull) feces sampled at three locations in Southcentral Alaska yielded isolates that harbored plasmid-encoded blaKPC-2 or chromosomally-encoded blaOXA-48, and genes associated with antimicrobial resistance to up to eight antibiotic classes.
    By
    Ecosystems, Alaska Science Center

    Satellite tracking of gulls and genomic characterization of fecal bacteria reveals environmentally mediated acquisition and dispersal of antimicrobial resistant Escherichia coli on the Kenai Peninsula, Alaska

    Gulls (Larus spp.) have frequently been reported to carry Escherichia coli exhibiting antimicrobial resistance (AMR E. coli); however, the pathways governing the acquisition and dispersal of such bacteria are not well-described. We equipped 17 landfill-foraging gulls with satellite transmitters and collected gull fecal samples longitudinally from four locations on the Kenai Peninsula, Alaska to as
    By
    Ecosystems, Alaska Science Center

    Acquisition and dissemination of cephalosporin-resistant E. coli in migratory birds sampled at an Alaska landfill as inferred through genomic analysis

    Antimicrobial resistance (AMR) in bacterial pathogens threatens global health, though the spread of AMR bacteria and AMR genes between humans, animals, and the environment is still largely unknown. Here, we investigated the role of wild birds in the epidemiology of AMR Escherichia coli. Using next-generation sequencing, we characterized cephalosporin-resistant E. coli cultured from sympatric gulls
    By
    Ecosystems, Contaminant Biology, Alaska Science Center

    Pre-USGS Publications

    Muellner, U., G. Fournie, P. Muellner, C. A. Ahlstrom, and D. U. Pfeiffer. 2018. Epidemix - an Interactive Multi-Model Application for Teaching and Visualizing Infectious Disease Transmission. Epidemics 23:49-54. doi:10.1016/j.epidem.2017.12.003.
    Ahlstrom, C. A., P. Muellner, G. Lammers, M. Jones, S. Octavia, R. Lan, and J. Heller. 2017. Shiga-toxin producing E. coli O157 shedding dynamics in an Australian beef herd. Frontiers in Veterinary Science 4:200. doi:10.3389/fvets.2017.00200.
    Ahlstrom, C. A., C. S. Manuel, H. C. Den Bakker, M. Wiedmann, and K. K. Nightingale. 2017. Molecular Ecology of Listeria spp., Salmonella, Escherichia coli O157:H7, and non-O157 Shiga Toxin Producing Escherichia coli in Pristine Natural Environments in Northern Colorado. Journal of Applied Microbiology. doi:10.1111/jam.13657.
    Ahlstrom, C. A., P. Muellner, S. Spencer, S. Hong, A. Saupe, A. Rovira, C. Hedberg, A. Perez, and J. Alvarez. 2017. Inferring source attribution from a multi-year multi-source dataset of Salmonella in Minnesota. Zoonoses and Public Health 64(8):589-598. doi:10.1111/zph.12351.
    Bauman, C. A., A. Jones-Bitton, C. A. Ahlstrom, L. Mutharia, J. De Buck, J. Jansen, D. F. Kelton, and P. Menzies. 2017. Identification of Mycobacterium avium ssp. paratuberculosis strains isolated from dairy goats and dairy sheep in Ontario, Canada. Canadian Journal of Veterinary Research 81(4):304-307.
    Hong, S., A. Rovira, P. Davies, C. A. Ahlstrom, P. Muellner, A. Rendahl, K. Olsen, J. B. Bender, S. Wells, A. Perez, and J. Alvarez. 2016. Serotypes and antimicrobial resistance in Salmonella enterica recovered from clinical samples from cattle and swine in Minnesota, 2006 to 2015. International Journal of Parasitology: Parasites and Wildlife 11(12):e0168016. doi:10.1371/journal.pone.0168016.
    Muellner, P., U. Muellner, M. C. Gates, T. Pearce, C. A. Ahlstrom, D. O'Neill, D. Brodbelt, and N. J. Cave. 2016. Evidence in Practice – A Pilot Study Leveraging Companion Animal and Equine Health Data from Primary Care Veterinary Clinics in New Zealand. Frontiers in Veterinary Science 3:116. doi:10.3389/fvets.2016.00116.
    Davidson, F., C. A. Ahlstrom, J. De Buck, H. G. Whitney, and K. Tahlan. 2016. Examination of Mycobacterium avium subspecies paratuberculosis mixed genotype infections in dairy animals using a whole genome sequencing approach. PeerJ 4:e2793. doi:10.7717/peerj.2793.
    Ahlstrom, C. A., H. W. Barkema, and J. De Buck. 2016. Relative frequency of 4 major strain types of Mycobacterium avium ssp. paratuberculosis in Canadian dairy herds using a novel single nucleotide polymorphism-based polymerase chain reaction. Journal of Dairy Science 99(10):8297-8303. doi:10.3168/jds.2016-11397.
    Ahlstrom, C. A., H. W. Barkema, K. Stevenson, R. N. Zadoks, R. Biek, R. Kao, H. Trewby, D. Haupstein, D. F. Kelton, G. Fecteau, O. Labrecque, G. P. Keefe, S. L. B. McKenna, K. Tahlan, and J. De Buck. 2016. Genome-wide diversity and phylogeography of Mycobacterium avium subsp. paratuberculosis in Canadian dairy cattle. PLoS One 11:e0149017. doi:10.1371/journal.pone.0149017.
    Ahlstrom, C. A., H. W. Barkema, K. Stevenson, R. N. Zadoks, R. Biek, R. Kao, H. Trewby, S. Hendrick, D. Haupstein, D. F. Kelton, G. Fecteau, O. Labrecque, G. P. Keefe, S. L. B. McKenna, and J. De Buck. 2015. Limitations of variable number of tandem repeat typing identified through whole genome sequencing of Mycobacterium avium subsp. paratuberculosis on a national and herd level. BMC Genomics 16:161. doi:10.1186/s12864-015-1387-6.
    Den Bakker, H. C., S. Warchocki, E. M. Wright, A. F. Allred, C. A. Ahlstrom, C. S. Manuel, M. J. Stasiewicz, A. Burrell, S. Roof, L. Strawn, E. D. Fortes, K. K. Nightingale, D. Kephart, and M. Wiedmann. 2014. Listeria floridensis sp. nov., Listeria aquatica sp. nov., Listeria cornellensis sp. nov., Listeria riparia sp. nov., and Listeria grandensis sp. nov., from agricultural and natural environments. International Journal of Systematic and Evolutionary Microbiology 64:1882-1889. doi:10.1099/ijs.0.052720-0.
    Ahlstrom, C. A., H. W. Barkema, and J. De Buck. 2014. Improved Short-Sequence-Repeat Genotyping of Mycobacterium avium subsp. paratuberculosis by Using Matrix-Assisted Laser Desorption Ionization—Time of Flight Mass Spectrometry. Applied and Environmental Microbiology 80:534-539. doi:10.1128/AEM.03212-13.
    Zadoks, R. N., H. M. Griffiths, M. A. Munoz, C. A. Ahlstrom, G. J. Bennett, E. Thomas, and Y. H. Schukken. 2011. Sources of Klebsiella and Raoultella species on dairy farms: be careful where you walk. Journal of Dairy Science 94(2):1045-1051. doi:10.3168/jds.2010-3603.
    Munoz, M. A., G. J. Bennett, C. A. Ahlstrom, H. M. Griffiths, Y. H. Schukken, and R. N. Zadoks. 2008. Cleanliness Scores as Indicator of Klebsiella Exposure in Dairy Cows. Journal of Dairy Science 91(10):3908-3916. doi:10.3168/jds.2008-1090.
    Munoz, M. A., C. A. Ahlstrom, B. J. Rauch, and R. N. Zadoks. 2006. Fecal Shedding of Klebsiella pneumoniae by Dairy Cows. Journal of Dairy Science 89(9):3425-3430. doi:10.3168/jds.S0022-0302(06)72379-7.
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