+
Related Topics
Cards In This Set
| Front | Back |
|
What are exotoxins? give examples
|
Proteins secreted by Gm+ and Gm- bacteria
-heat liable and immunogenic -enter blood and spread to other parts of body to cause damage away from colonization site -cytolytic toxins: cause cell lysis -neurotoxins: interfere with nerve cell function -enterotoxins: affect cell lining of GI tract -vaccine is effective |
|
What are toxoids?
|
-exotoxins that have been treated with heat to make them non-toxic but still able to stimulate production of neutralizing antibodies
|
|
What are endotoxins? how do they work? what are their symptoms?
|
Released only when gm- bacteria die or are phagocytosed
-LPS from outer membrane -heat stable and don't produce strong immunogenic response -bind to receptor on macrophages resulting in activation of transcription factors and release of cytokines -fever, endotoxin shock |
|
Describe the bacterium of cholerae
|
-motile, gm- rod with single flagellum
-only affects humans -two serogroups |
|
What is the disease caused by cholerae?
|
-spread by fecal oral route viz contaminated water and food
-people with bad immunity and low stomach ph are more susceptible -caused by enterotoxin -onset of watery diarrhea with flakes of mucus and epithelial cells -major dehydration and loss of electrolytes |
|
How do you diagnose cholera?
|
-stool sample of infected person
-presence of rice water stool |
|
How does the cholera toxin (CT) work?
|
-CT is protein complex of 5 binding subunits B and 1 enzymatic subunit A
-B binds to receptor on intestinal epithelial cell and forms pore for A to go through into cytoplasm of cell -A activates conversion of ATP to cAMP -cAMP activated secretion of chlorine ions followed by water potassium and sodium due to osmosis -massive loss of water and electrolytes causing dehydration |
|
How does cholera evade host defenses?
|
-sensitive to stomach pH
-low infectious dose in people that have gastric issues and higher stomach pH -resistant to bile salts and adhere to and penetrate mucous layer of intestine -TCP pili aids in adhering and causes bacteria to aggregate |
|
How can cholera be treated?
|
-re hydration therapy with water and electrolytes and salts and glucose
-glucose stimulates uptake of salts and water by mucous cells |
|
What is the vaccine for cholera? how can cholera be prevented?
|
Natural infections stimulates antibody production against antigens and toxin
-reinfections is rare as body develops local immune defense -oral live attenuated vaccine is effective against one serotype of cholera -prevent by proper sanitation -boiling water and cooking meats properly -proper sewage treatments |
