Shigella
Shigella
Introduction: Shigella is a very infectious bacteria that causes Shigellosis.
I. Morphology of Shigella
• Gram-negative
• Nonmotile bacillus
II. 4 different species of Shigella
• S. dysenteriae o Most severe type of shigellosis because it secretes Shiga Toxin
Shiga toxin- stops protein synthesis in host’s cell.
• S. flexneri o Is the predominate species in developing countries.
• S. boydii
• S. sonnei o Is the most common species isolated in industrialized nations.
III. All four species produce type 3 Secretions Systems and diarrhea-producing Enterotoxins.
1. Type 3 secretion systems o Composed of 20 diverse polypeptides. o Inserts into hosts cell membrane & forms a path for bacterial proteins.
2. Enterotoxins o Bind to surface proteins on epithelial cells. o Trigger loss of water and electrolytes o Shiga Toxin is an endotoxin that creates a much more severe form of shigellosis.
IV. What is Shigellosis?
• Shigellosis is an intestinal disease caused by Shigella bacteria.
• It causes fever, abdominal cramps, diarrhea and bloody stool.
V . How is it spread & where is it found?
• The bacteria is released in stool.
• It can be spread by: o Direct contact with stool o Through contaminated food and water.
• Common in developing countries & associated with poor sanitation and crowded living conditions.
VI. Pathogenesis
• Ingestion and attachment of bacteria
• Bacteria break through mucosa
• Colonization and cell multiplication in epithelial cells of colon
• Production of Type 3 Secretions & enterotoxins o Blocks and inhibits protein synthesis o Death of cells
• Shiga toxin results in a more severe form of cramps, diarrhea, etc.
VII. Treatment & Prevention.
• Treatment o Supportive care.. watch for dehydration…etc o Use of antimicrobial drugs to shorten the length of the disease.
• Prevention o Chlorination of water o Correct disposal of sewage
VIII. References
• Bauman W, Robert.
Introduction: Shigella is a very infectious bacteria that causes Shigellosis.
I. Morphology of Shigella
• Gram-negative
• Nonmotile bacillus
II. 4 different species of Shigella
• S. dysenteriae o Most severe type of shigellosis because it secretes Shiga Toxin
Shiga toxin- stops protein synthesis in host’s cell.
• S. flexneri o Is the predominate species in developing countries.
• S. boydii
• S. sonnei o Is the most common species isolated in industrialized nations.
III. All four species produce type 3 Secretions Systems and diarrhea-producing Enterotoxins.
1. Type 3 secretion systems o Composed of 20 diverse polypeptides. o Inserts into hosts cell membrane & forms a path for bacterial proteins.
2. Enterotoxins o Bind to surface proteins on epithelial cells. o Trigger loss of water and electrolytes o Shiga Toxin is an endotoxin that creates a much more severe form of shigellosis.
IV. What is Shigellosis?
• Shigellosis is an intestinal disease caused by Shigella bacteria.
• It causes fever, abdominal cramps, diarrhea and bloody stool.
V . How is it spread & where is it found?
• The bacteria is released in stool.
• It can be spread by: o Direct contact with stool o Through contaminated food and water.
• Common in developing countries & associated with poor sanitation and crowded living conditions.
VI. Pathogenesis
• Ingestion and attachment of bacteria
• Bacteria break through mucosa
• Colonization and cell multiplication in epithelial cells of colon
• Production of Type 3 Secretions & enterotoxins o Blocks and inhibits protein synthesis o Death of cells
• Shiga toxin results in a more severe form of cramps, diarrhea, etc.
VII. Treatment & Prevention.
• Treatment o Supportive care.. watch for dehydration…etc o Use of antimicrobial drugs to shorten the length of the disease.
• Prevention o Chlorination of water o Correct disposal of sewage
VIII. References
• Bauman W, Robert.
References: • Bauman W, Robert. Microbiology with Diseases by Body System (3 ed).