Showing posts with label Typhus Fever. Show all posts
Showing posts with label Typhus Fever. Show all posts

Rickketsia

General characters
·         They are small Gram negative bacilli adapted to obligate intracellular parasitism, transmitted by arthropod vectors. They are primary parasites of arthropods such as lice, fleas, ticks, in which they are found in the alimentary canal. In vertebrates they infect vascular endothelium, reticuloendothelial cells.
·         This pleomorphic coccobacilli are nonmotile, noncapsulated. They stain bluish purple with Giemsa stain. It has a 3 layered cell wal  , a trilaminar plasma membrane and an outer slime layer.
·         Growth occurs in the cytoplasm of infected cells, nucleus etc. the optimum temperature is 32-350C. they are readily cultivated in the yolksac of chick embryos, HeLa cells etc., in arthropods.
·         They multiply by binary fission.
·         They are inactivated by physical and chemical agents. They are rapidly destroyed at room temperature when seperated from host components, susceptible to tetracycline, chloramphenicol, ciprofloxacin, lysozyme. Sulfonamides enhance the growth and worsen the condition of patients.
·         They possess both RNA and DNA.
·         They are large enough to be seen under the light microscope and are held back by bacterial filters.

Rhabdoviruses

The family Rhabdoviridae comprises more than 200 viruses which infect mammals, reptiles, birds, fishes, insects and plants. It has two ge...