What Is Microbiology - Plague

​Plague


Plague is caused by Yersinia pestis. Yersinia pestis can be detected based on direct examination of the blood, sputum, or pus from buboes. 

Yersinia pestis is a gram negative rod. There are three different forms of plague caused by yersinia pestis. These include bubonic plague, pneumonic plague and septicemic plague.

Bubonic plague may present with high fever and large swollen groin or axilla lymph nodes ( bubos).  The swelling of the lymph nodes may occur due to replication of Yersinia pestis in the macrophages.

Pneumonic plague may occur from embolization of the bacteremic organism into the lung and inhalation of the aerosol which is infectious.  Pneumonic plague is highly fatal. 

Septicemic plague may lead to disseminated intravascular coagulation with necrosis of the peripheral blood vessel. Septicemic plague is also known as black death. 

The common mode of transmission is from the bites of infected fleas from the rat or wild animals which are known as urban plagues and sylavatic plague. Other forms of transmission may include inhalation of the respiratory aerosol.

The common virulence factors of yersinia pestis may include plasminogen activator protease ( involved in spreading of infectious), endotoxin, protein capsule and yersinia outer proteins ( YOPS proteins).  The virulence factors may interfere and disrupt the signaling of the host cell and the cytoskeleton of the host cell.

The treatment of plague may include antibiotic such as tetracycline, streptomycin, trimethoprim - sulfamethoxazole and chloramphenicol.