Yersinia pestis animated Yersinia pestis infections

Yersinia pestis appearance

  • Gram-negative coccobacilli or short rods with bipolar staining (giving it a safety pin appearance; in cultures, bipolar staining is usually not so well seen)
  • nonmotile
  • non-spore-forming
  • usually encapsulated (protein capsule)

Infections caused by Yersinia pestis

Plague is a disease that affects humans and other mammals. It is caused by the bacterium, Yersinia pestis. Humans usually get plague after being bitten by a rodent flea that is carrying the plague bacterium or by handling an animal infected with plague. Plague is infamous for killing millions of people in Europe during the Middle Ages. Today, modern antibiotics are effective in treating plague. Without prompt treatment, the disease can cause serious illness or death.

Plague symptoms depend on how the patient was exposed to the plague bacteria. Plague can take different clinical forms, but the most common are bubonic, pneumonic and septicemic.

Types of Plague

Yersinia pestis treatment
Should be guided by in vitro susceptibility tests!!

  • streptomycin
  • chloramphenicol
  • gentamicin
  • doxycycline
Resistant strains have been isolated; treatment should be guided by antibiotic sensitivities where available.
Antibiotic treatment alone is insufficient for some patients, who may also require circulatory, ventilator, or renal support.

Yersinia pestis vaccination

Since human plague is rare in most parts of the world, routine vaccination is not needed other than for those at particularly high risk of exposure, nor for people living in areas with enzootic plague, such as the western United States. It is not even indicated for most travellers to countries with known recent reported cases, particularly if their travel is limited to urban areas with modern hotels.

A formalin-inactivated vaccine once was available in the United States for adults at high risk of contracting the plague until removal from the market by the U.S. Food and Drug Administration. It was of limited effectiveness and could cause severe inflammation. Experiments with genetic engineering of a vaccine based on F1 and V antigens are underway and show promise (Wikipedia).




Colony appearance

Yersinia pestis Yersinia pestis cell morphology The causative agent of plague