Introduction
Y. pestis is a bacterium responsible for three major plague outbreaks. It is usually transmitted by bite from fleas or rats, or in extreme pandemics by air[32]. Each pandemic is identified with different groups of strains ("biovars", see picture at bottom): Antiqua (Biblic, Egyptian, Greek, Roman[12]), Medievalis (Black Death), and Orientalis (Modern). Physically it is bacillus shaped, stains gram-negative, is non-motile, and grows at 26-37oC[11]. Y. pestis uses both resperation and fermentation to meet its energy needs[12].
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Domain: Bacteria
Kingdom: Eubacteria Phylum: Proteobacteria Class: Gammaproteobacteria Order: Enterobacteriales Family: Enterobacteriaceae Genus: Yersinia Species: Y. pestis |
Evolution & Virulence
Y. pestis shares its genus with two other species: Y. enterocolitica and Y. pseudotuberculosis. Y. pestis is hypothesized to have emerged from Y. pseudotuberculosis as recently as 1500 to 20,000 years ago, yet it has highly differentiated symptoms and patterns of transmission; Y. enterocolitica and Y. pseudotuberculosis both are transmitted orally, typically through contaminated food or water, and are rarely fatal[32]. All three species contain a common plasmid (pCD1), however Y. pestis contains two additional plasmids that increase its virulence[32].
References
[11]https://microbewiki.kenyon.edu/index.php/Yersinia
[12]http://en.wikipedia.org/wiki/Plague_(disease)
[32]Bi, Y. Y., Wang, X. X., Han, Y. Y., Guo, Z. Z., & Yang, R. R. (2012). Yersinia pestis Versus Yersinia pseudotuberculosis: Effects on Host Macrophages. Scandinavian Journal Of Immunology, 76(6), 541-551. doi:10.1111/j.1365-3083.2012.02767.x
[12]http://en.wikipedia.org/wiki/Plague_(disease)
[32]Bi, Y. Y., Wang, X. X., Han, Y. Y., Guo, Z. Z., & Yang, R. R. (2012). Yersinia pestis Versus Yersinia pseudotuberculosis: Effects on Host Macrophages. Scandinavian Journal Of Immunology, 76(6), 541-551. doi:10.1111/j.1365-3083.2012.02767.x