Professional Education

  • Doctor of Philosophy, Stanford University, MI-PHD (2019)
  • Doctor of Veterinary Medicine, University of California Davis, Veterinary Medicine (2009)
  • Bachelor of Science, University of California Santa Cruz, Marine Biology (2003)

Stanford Advisors


All Publications

  • Marine mammals harbor unique microbiotas shaped by and yet distinct from the sea. Nature communications Bik, E. M., Costello, E. K., Switzer, A. D., Callahan, B. J., Holmes, S. P., Wells, R. S., Carlin, K. P., Jensen, E. D., Venn-Watson, S., Relman, D. A. 2016; 7: 10516-?


    Marine mammals play crucial ecological roles in the oceans, but little is known about their microbiotas. Here we study the bacterial communities in 337 samples from 5 body sites in 48 healthy dolphins and 18 healthy sea lions, as well as those of adjacent seawater and other hosts. The bacterial taxonomic compositions are distinct from those of other mammals, dietary fish and seawater, are highly diverse and vary according to body site and host species. Dolphins harbour 30 bacterial phyla, with 25 of them in the mouth, several abundant but poorly characterized Tenericutes species in gastric fluid and a surprisingly paucity of Bacteroidetes in distal gut. About 70% of near-full length bacterial 16S ribosomal RNA sequences from dolphins are unique. Host habitat, diet and phylogeny all contribute to variation in marine mammal distal gut microbiota composition. Our findings help elucidate the factors structuring marine mammal microbiotas and may enhance monitoring of marine mammal health.

    View details for DOI 10.1038/ncomms10516

    View details for PubMedID 26839246

    View details for PubMedCentralID PMC4742810

  • Bartonella and Toxoplasma Infections in Stray Cats from Iraq AMERICAN JOURNAL OF TROPICAL MEDICINE AND HYGIENE Switzer, A. D., McMillan-Cole, A. C., Kasten, R. W., Stuckey, M. J., Kass, P. H., Chomel, B. B. 2013; 89 (6): 1219-1224


    Because of overpopulation, stray/feral cats were captured on military bases in Iraq as part of the US Army Zoonotic Disease Surveillance Program. Blood samples were collected from 207 cats, mainly in Baghdad but also in North and West Iraq, to determine the prevalence of Bartonella and Toxoplasma infections. Nine (4.3%) cats, all from Baghdad, were bacteremic with B. henselae type I. Seroprevalence was 30.4% for T. gondii, 15% for B. henselae, and 12.6% for B. clarridgeiae. Differences in Bartonella prevalence by location were statistically significant, because most of the seropositive cats were from Baghdad. There was no association between T. gondii seropositivity and either of the two Bartonella species surveyed. This report is the first report on the prevalence of Bartonella and T. gondii among stray cats in Iraq, which allows for better evaluation of the zoonotic risk potential to the Iraqi people and deployed military personnel by feral cat colonies.

    View details for DOI 10.4269/ajtmh.13-0353

    View details for Web of Science ID 000328726100028

    View details for PubMedID 24062480

    View details for PubMedCentralID PMC3854905

  • Infection of pregnant mice with Listeria monocytogenes induces fetal bradycardia PEDIATRIC RESEARCH Hardy, J., Kirkendoll, B., Zhao, H., Pisani, L., Luong, R., Switzer, A., McConnell, M. V., Contag, C. H. 2012; 71 (5): 539-545


    Listeriosis is one of the most lethal bacterial diseases for fetuses and infants. However, pregnant women who get infected with Listeria may experience only mild symptoms, making the diagnosis difficult, even when the fetus is fatally infected.To reveal features of this infection, we conducted a multimodality imaging study of Listeria-induced miscarriage, using a pregnant mouse model. In this model, fetal morbidity and mortality can be observed in utero, noninvasively, and the timing and extent of infection can be carefully controlled. By employing in vivo bioluminescence imaging (BLI), perinatal infections were localized over time such that a correlation of infection to outcome could be determined without the need to kill the animal subject. The morbidity and viability of fetuses were assessed with ultrasound, and fetal morphology was imaged using magnetic resonance imaging (MRI).The ultrasound revealed sustained fetal bradycardia, the slowing of the fetal heartbeat, in infected fetuses, with an association between slowed fetal heart rate and strong bioluminescent signal.Uninfected fetuses showing no bioluminescent signal in the same uterine horn exhibited normal heartbeats. Thus, fetal bradycardia during infection was localized to the infected fetus and was not systemic or disseminated.

    View details for DOI 10.1038/pr.2012.2

    View details for PubMedID 22314663

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