College of Veterinary Medicine

Veterinary Microbiology and Pathology

Margaret A. Davis, DVM, MPH, PhD


PhD: Washington State University. 2002
MPH: University of Washington,  1992
DVM: Washington State University, 1985
B.S. Zoology: University of Massachusetts. 1976


My research has focused on the molecular epidemiology of zoonotic foodborne pathogens including non-Typhoid Salmonella, E. coli O157:H7 and other STEC, Campylobacter spp. and multi-drug antibmicrobial resistance in Salmonella and other Gram-negative bacteria. I am particularly interested in the use of genotyping methods to study transmission routes of zoonotic pathogens and their maintenance and dissemination in reservoir species. I am also interested in exploring the causes of antimicrobial resistance in bacterial pathogens.

Selected Publications

Broschat SL, Call DR, Davis MA, Meng D, Ahmed R, Besser TE. Improved identification of epidemiologically related strains of Salmonella enterica using a fusion algorithm based on PFGE and MLVA. J Clin Microbiol. 2010 Aug 25. [Epub ahead of print]

Hoelzer K, Soyer Y, Rodriguez-Rivera LD, Cummings KJ, McDonough PL, Schoonmaker-Bopp DJ, Root TP, Dumas NB, Warnick LD, Gröhn YT, Wiedmann M, Baker KN, Besser TE, Hancock DD, Davis MA. The prevalence of multidrug resistance is higher among bovine than human Salmonella enterica serotype Newport, Typhimurium, and 4,5,12:i:- isolates in the United States but differs by serotype and geographic region. Appl Environ Microbiol. 2010 Sep;76(17):5947-59. Epub 2010 Jul 16.

Davis MA, Baker NKN, Orfe LH, Shah D, Besser TE, Call DR. Discovery of a gene conferring multiple aminoglycoside resistance in Escherichia coli. Antimicrob Agents Chemother 2010;54(6):2666-9.

Davis MA, Lim JY, Soyer Y, Harbottle H, Chang YF, New D, Orfe LH, Besser TE, Call DR. Development and validation of a resistance and virulence gene microarray targeting Escherichia coli and Salmonella enterica. J Microbiol Methods 2010 Mar 31 [Epub ahead of print].

Adhikari B, Besser TE, Gay JM, Fox LK, Hancock DD, Davis MA. Multilocus variable number of tandem repeats analysis and plasmid profiling to study the occurrence of blaCMY-2 within a PFGE defined clade of Salmonella enterica serovar Typhimurium Appl Environ Microbiol 2010;76:69-74.

Adhikari B, Besser TE, Gay JM, Fox LK, Davis MA, Cobbold RN, Berge AC, Hancock DD. The role of animal movement, including off-farm rearing of heifers, in the interherd transmission of multidrug-resistant Salmonella. J Dairy Sci. 2009 Sep;92(9):4229-38.

Adhikari B, Besser TE, Gay JM, Fox LK, Davis MA, Cobbold RN, Berge AC, McClanahan R, Hancock DD. Introduction of new multidrug-resistant Salmonella enterica strains into commercial dairy herds. J Dairy Sci. 2009 Sep;92(9):4218-28.

Soyer, Y., A. Moreno Switt, M.A. Davis, J. Maurer, P.L. McDonough, D. J. Schoonmaker-Bopp, N. B. Dumas, T. Root, L.D. Warnick, Y.T. Gröhn and M. Wiedmann. 2009.Salmonella 4,5,12:i:-: an emerging Salmonella serotype that represents multiple distinct clones. J. Clin. Microbiol 2009 Sep 9. [Epub ahead of print]

Davis MA, Baker, KNK, Call DR, Warnick LD, Soyer Y, Wiedmann M, Gröhn Y, McDonough PL, Hancock DD, Besser TE. 2009. Multiple locus variable number of tandem repeats typing method for Salmonella enterica serovar Newport. J Clin Microbiol 2009;47:1934-8.

Call DR, Davis MA, Sawant AA Antimicrobial resistance in beef and dairy cattle production. Anim Health Res Rev. 2008 Dec;9(2):159-67. Epub 2008 Nov 5.

Call DR, Orfe L, Davis MA, Lafrentz S, Kang MS. Impact of compounding error on strategies for subtyping pathogenic bacteria. Foodborne Pathog Dis. 2008 Aug;5(4):505-16.

Davis MA, Evermann JF, Petersen CR, VanderSchalie J, Besser TE, Huckabee J, Daniels JB, Hancock DD, Leslie M, Baer R. Serological survey for antibodies to Leptospira in dogs and raccoons in Washington State. Zoonoses Public Health. 2008 Oct;55(8-10):436-42.

Chen CYC, Davis MA, LaPatra SE, Cain KE, Snekvik KR, Call DR. 2008 Genetic diversity of Flavobacterium psychrophilum recovered from commercially raised rainbow trout, Oncorhynchus mykiss, and spawning coho salmon, Oncorhynchus kisutch. Journal of Fish Diseases 2008;31:765-773.

Cobbold RN, Davis MA, Rice DH, Szymanski M, Tarr PI, Besser TE, Hancock, D.D. 2008. Associations between bovine, human, and raw milk and beef isolates of non-O157 Shiga-toxigenic Escherichia coli within a restricted geographic area of the USA. Journal of Food Protection. 2008;71(5):1023-7.

Davis MA, Besser TE, Eckmann K, MacDonald JK, Green D, Hancock DD, Baker KNK, Warnick LD, Soyer Y, Wiedmann M, Call DR, Multidrug-resistant Salmonella Typhimurium, Pacific Northwest, United States. Emerg Infect Dis. 2007 Oct;13(10):1583-6.

Davis MA, Hancock DD, Besser TE, Daniels JB, Baker KNK, Call DR. Antimicrobial resistance in Salmonella enterica serovar Dublin isolates from beef and dairy sources. Veterinary Microbiology Vet Microbiol. 2007 Jan 31;119(2-4):221-30. Epub 2006 Sep 1.

Dunowska M, Morley PS, Traub-Dargatz JL, Davis MA, Patterson G, Frye JG, Hyatt DR, Dargatz DA. Comparison of Salmonella enterica serotype Infantis isolates from a veterinary teaching hospital. J Appl Microbiol 2007; 102(6):1527-36.

Davis MA, Rice DH, Sheng H, Hancock DD, Besser TE, Cobbold R, Hovde CJ. Comparison of cultures from rectoanal junction mucosal swabs and feces for detection of Escherichia coli O157 in dairy heifers. Applied and Environmental Microbiology 2006;72(5):3766-70.

Davis MA, Sheng H, Newman J, Hancock DD, Hovde CJ. Comparison of a waterless hand hygiene preparation and soap and water hand washing to reduce coliforms on hands in animal exhibit settings. Epidemiology and Infection 2006;134(5):1024-8.

Cobbold RN, Rice DH, Davis MA, Besser TE, Hancock DD. Long-term persistence of multi-drug-resistant Salmonella enterica serovar Newport in two dairy herds. Journal of the American Veterinary Medical Association 2006;228(4):585-91.

Davis MA, Cloud-Hansen KA, Carpenter J, Hovde CJ. Escherichia coli O157:H7 in Environments of Culture-Positive Cattle. Applied and Environmental Microbiology. 2005;71(11):6816-22.

Sheng H, Davis MA, Knecht HJ, Hancock DD, Van Donkersgoed J, Hovde CJ. Characterization of a shiga toxin-, intimin-, and enterotoxin hemolysin-producing Escherichia coli ONT:H25 strain commonly isolated from healthy cattle. Journal of Clinical Microbiology. 2005;43(7):3213-20.

Sheng H, Davis MA, Knecht HJ, Hovde CJ. Rectal administration of Escherichia coli O157:H7: novel model for colonization of ruminants. Applied and Environmental Microbiology 2004;70 (8):4588-4595.

LeJeune JT, Davis MA. Outbreaks of zoonotic enteric disease associated with animal exhibits. Journal of the American Veterinary Medical Association 2004;224(9):1440-1445.

Davis MA, Hancock DD, Besser T, Rice DH, Hovde CJ, DiGiacomo R, Samadpour M, Call DR. Correlation between geographic distance and genetic similarity in an international collection of bovine fecal Escherichia coli O157:H7 isolates. Epidemiology and Infection 2003;131:923-930.

Davis MA, Hancock DD, Rice DH, Call DR, DiGiacomo R, Samadpour M, Besser T. Feedstuffs as a vehicle of cattle exposure to Escherichia coli O157:H7 and Salmonella enterica. Veterinary Microbiology 2003;95:199-210.

Davis MA, Hancock DD, Besser TE, Call D. Evaluation of pulsed-field gel electrophoresis as a tool for determining the degree of genetic relatedness between strains of Escherichia coli O157:H7. Journal of Clinical Microbiology 2003;41:1843-1849.

Besser TE, Hancock D, Davis MA. The veterinarian's role in controlling the emergence and dissemination of drug-resistant bacteria. Journal of Veterinary Medical Education 2003;30(2):136-9.

Davis MA, Hancock DD, Besser TE. Multiresistant clones of Salmonella enterica: The importance of dissemination. Journal of Laboratory and Clinical Medicine. 2002 Sep;140(3):135-41.

Hancock D, Besser T, LeJeune J, Davis M, Rice D. The control of VTEC in the animal reservoir. International Journal of Food Microbiology 2001;66:71-78.

Hancock D, Besser T, Gay J, Rice D, Davis M, Gay C. The global epidemiology of multiresistant Salmonella enterica serovar Typhimurium DT104. Chapter 11, Emerging Diseases of Animals, Edited by C Brown and C Bolin. 2000 ASM Press, Washington, DC.

Akiba M, Rice DH, Davis MA, Masuda T, Sameshima T, Nakazawa M, Hancock DD. A comparison of Escherichia coli O157 isolates from cattle in Japan and the USA by molecular biological methods. Epidemiology and Infection. 2000;125(1):221-4.

Davis MA, Hancock DD, Besser TE, Rice DH, Gay JM, Gay C, Gearhart L, DiGiacomo R. Changes in antimicrobial resistance among Salmonella enterica serovar Typhimurium isolates from humans and cattle in the northwestern United States, 1982-1997. Emerging Infectious Diseases 1999;5(6):802-806.

Alexander ER, Boase J, Davis M, Kirchner L, Osaki C, Tanino T, Samadpour M, Tarr P, Goldoft M, Lankford S, Kobayashi J, Stehr-Green P, Bradley P, Hinton B, Tighe P, Pearson B, Flores GR, Abbott S, Bryant R, Werner SB, Vugia DJ. Escherichia coli O157:H7 Outbreak Linked to Commercially Distributed Dry-Cured Salami --1994 Washington and California, MMWR 1995;44(09);157-160.

Bell BP, Goldoft M, Griffin PM, Davis MA, Gordon DC, Tarr PI, Bartleson CA, Lewis JH, Barrett TJ, Wells JG, Baron R, Kobayashi J.  A multistate outbreak of Escherichia coli O157:H7 -- associated bloody diarrhea and hemolytic uremic syndrome from hamburgers. Journal of the American Medical Association 1994;272:1349-1353.

Last Edited: Sep 13, 2010 1:22 PM   

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