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Aeromonas hydrophila

NATHAN WILHITE

THE BASICS •  GRAM-NEGATIVE, ROD-SHAPED BACTERIA

•  INFECTS FISH, REPTILES, HUMANS AND AMPHIBIANS

•  FOUND WORLDWIDE:

•  NOT A CAUSE OF MASS DIE-OFFS/OUTBREAKS

•  WHAT’S THE BIG DEAL? •  UBIQUITOUS •  SYMBIOTIC •  DEFENSE

•  OPPORTUNISTIC

http://www.snap.is/files/2013/09/NorthfordWoodFrogsBreeding-1600-1200x500.jpg

http://gregsnaturalhistory.com/wp-content/uploads/2012/02/A-hand-full-of-life.jpg

PATHOLOGY

Signs:

•  Red Leg??

•  Ulceration

•  Hemorrhaging

•  Edema

•  Anorexia

•  Lethargy

•  Necrosis

Amphibian lines of bacterial defense: 1. Skin 2. Innate Immune System 3. Adaptive Immune System

Hill, Newman, et. al: • Wild Xenopus laevis -oocyte removal • 1 female with clinical signs -lip ulcer and liver tested -digit tested for Chytrid

and Ranavirus • Aeromonas +, Batrachochytrium +, and Micrococcus +

• Chytrid? Surgery Trauma?

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2846011/#!po=22.7273

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Tennessen, et. al.:

• Lithobates pipiens • Anti-microbial peptides: -4 new peptides found and tested -3 effective against chytrid fungus -None effective on A. hydrophila

Schadich, et. al.: • Xenopus laevis, Litoria aurea, Litoria

raniformis, Litoria ewingii

• ECP’s vs. AMP’s • Proteases secreted by A. hydrophila

allow for E. Coli growth

PATHOLOGY

http://www.californiaherps.com/frogs/images/rpipiens04.jpg

http://d3lp4xedbqa8a5.cloudfront.net/s3/digital-cougar-assets/AusGeo/2013/09/11/7527/-golden-bell-frog-lance-article.jpg

*Skin peptides/defenses don’t work

AN INTERESTING CASE….. Roth, et. al: • 133 Cascade frogs sampled for Batrachochytrium dendrobatidis

• 46 bacterial isolates

• 7%

Aeromonas • B.d vs bacteria • B.d vs A.h

Conclusions:

• Aeromonas hydrophila = strong anti-B.d activity in vitro

•  Exotoxins or ECP’s preventing Chytrid fungus?

•  Possible competitive exclusion of Chytrid fungus?

http://www.californiaherps.com/frogs/images/ryavapaiensisbd05.jpg

DECLINES Habitat Loss

Diseases

Exotic Species

Climate Change

Pollution Pet trades

Rollins-Smith: -Hypothalamus-Pituitary-Interrenal -Corticosteroids:

-Lymphocytes -Stimulated in TIMES OF STRESS!!!

• Metamorphosis • Explosive Breeding • Post-hibernation • Densities, Water Quality, Etc.

ALL INDUCE STRESS

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Aeromonas hydrophila

Symbiotic, ever-present bacteria

Normal anti-microbial skin peptides fail to suppress

Devastating pathological effects

Favorable-time invader

Additive mortality to every other possible stressor!!!

Can’t stop it without fixing everything else

SOURCES CITED Hill A. William, S. J. Newman, L. Craig, C. Carter, J. Czarra, J.P. Brown. 2010. Diagnosis of Aeromonas hydrophila, Mycobacterium species, and Batrachochytrium dendrobatidis in an African Clawed Frog (Xenopus laevis). Journal of the American Association for Laboratory Animal Science. 49:2:215-220. Rollins-Smith, A. Louise. Neuroendocrine-immune system interactions in amphibians - Implications for understanding global amphibian declines. Immunologic Research. 23:273-280. Roth, Tara; J. Foley; J. Worth; J. Piovia-Scott; K. Pope; S. Lawler. 2013. Bacterial flora on Cascades frogs in the Klamath mountains of California. Comparative Immunology, Microbiology, and Infectious Diseases. 36:6:591-598. Schadich, E.; and A.L.J. Cole. 2009. Inhibition of frog antimicrobial peptides by extracellular products of the bacterial pathogen Aeromonas hydrophila. Letters in Applied Microbiology. 49:3:384-387. Tennessen, A. Jacob; D. C. Woodhams; P. Charaund; et al. 2009. Variations in the expressed antimicrobial peptide repertoire of northern leopard frog (Rana pipiens) populations suggest intraspecies differences in resistance to pathogens. Development and Comparative Immunology. 33:12:1247-1257.