Habitat and Morphology of Shigella dysenteriae

Habitat of Shigella dysenteriae

1. They are found worldwide.
2. Humans are only the natural host.
3. They are also found in human intestinal tract.
4. They are mostly found in the area where there is overcrowded.
5. Prevalent in low waste management areas and no safe drinking water supply.
6. Houseflies serves as vectors.
7. They are also found in contaminated food and water.
8. They causes endemic dysentery in Africa, Southeast Asia and Indian Sub-continent.
9. Risk for day care ages (1-4 years) and elderly adults.
10. Custodial (Housekeeping) are also at high risk of infection.
11. They are spread by the fecal-oral route.

Morphology of Shigella dysenteriae

1. They are gram -ve small rod shaped bacteria.
2. They are non-capsulated.
3. They are 2-4 µm long and 0.4-0.6 µm wide.
4. They are non-sporing.
5. They are non-acid fast bacteria.
6. They have rounded ends.
7. Around 15 serotypes are present.
8. They are non-motile.

Genome (Sd17) of Shigella dysenteriae

1. They have one circular chromosome.
2. Number of nucleotides: 4,369,232
3. Number of genes: 4664
4. Plasmid: 182,726 nucleotides and 224 genes