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
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
Virulence Picture 1. Yersinia pestis
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;
Picture 2. Symptoms of bubonic plague. Epidemiology
Y.pestis is a zoonotic infection
humans are accidential host
natural reservoirs include rats (pic.3) squirrels, rabbits, and domestic animals
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
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
Disease
Picture 2. Symptoms of bubonic plague.
Epidemiology
Picture 3. Rat, natural reservoir of plague.