Yersinia+pestis

// ﻿ //Yersinia pestis

Yersinia pestis is the best-known human pathogens within the genus Yersinia. Y. pestis is a highly virulent pathogen that causes the highly fatal systemic disease known as plague.

Biology Virulence ﻿  ﻿﻿Picture 1. Yersinia pestis > > >
 * Y.pestis is gram-negative, facultatively anaerobic rods (pic.1)
 * fermenter, oxidase negative
 * lipopolysaccharide consists of somatic O polysaccharide, core polysaccharide (common antigen), and lipid A (endotoxin)
 * is covered with a protein capsule
 * resist killing (the type III secretion system mediates this properity)
 *  has two plasmids that encode virulence genes: fraction 1 gene (codes for an antiphagocytic protein capsule), and plasmino﻿gen activator (Pla) protease gene (degrades complement components C﻿3b and C5a, preventing opsonization and phagocytic migration;
 * show serum resistance

Disease

Picture 2. Symptoms of bubonic plague. ﻿ Epidemiology 
 * //Y.pestis// causes bubonic plague (pic. 2) (most commom) and pulmonary plague
 * both have a high mortality rate
 * //Y.pestis// is still out there: http://news.bbc.co.uk/1/hi/8182734.stm
 * //﻿Y.pestis// is a zoonotic infection
 * humans are accidential host
 * natural reservoirs include rats (pic.3) squirrels, rabbits, and domestic animals
 * <span style="font-family: Tahoma,Geneva,sans-serif; font-size: medium; line-height: 27px;">disease is spread by flea bites or direct contact with infected tissues or person to person by inhalation of infectious aerosols from a patient with pulmonary disease

Picture 3. Rat, natural reservoir of plague.