Term
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Definition
| The biochemical mechanisms whereby a bacterial can cause disease |
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Term
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Definition
| large inserts of DNA that include virulence genes not found in nonpathogenic members of the genera |
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Term
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Definition
| population density determines the regulation of virulence genes-- bacteria can communicate by releasing chemicals, and when they sense them they can change function (depends on population density) |
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Term
| Bacterial adhesins include: |
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Definition
1. fimbriae
2. glycocalyx
3. teichoic and lipotechoic acid
4. flagella
5. outer membrane proteins-- outer membrane encapsulates organism and flagella, so flagella are not antigens because they are masked |
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Term
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Definition
| the capacity to move towards a host surface via flagella--direct their movements according to certain chemicals in their environment |
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Term
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Definition
*Bacterium can hide inside the cell from host defense immune system.
*Utilized by a number of pathogens
*in an environment rich in nutrients
*penetration usually involves existing host cell internalization pathways
*invasins bind to host cell receptors |
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Term
| Methods to prevent phagocytic killing: |
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Definition
1. inhibition of phagolysosome fusion (Mycobacterium tuberculosis)
2. resistance to lysosomal enzymes (salmonella typhimurium) |
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Term
| Ways for bacteria to spread within host: |
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Definition
1. Intracellular pathogens may cause lysis which provides release past host epithelial barriers
2. intracellular pathogens may stay inside phagocytic cells, which are transported to lymph nodes- bacteria can then enter blood
3. some pathogens eneter deeper tissue by passing between eukaryotic cells forming epithelial barriers
4. pathogens capable of disseminating via the blood stream usually have special capabilties for aquiring iron. |
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Term
| type III secretion system |
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Definition
*bacterial secretion system for virulence enhancement
*delivers virulence determinants directly into host cells
*helps prevent neutralization of virulence factors by immune system |
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Term
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Definition
1. hyaluronidase
2. collagenase
3. coagulase
4. kinases
5. urease |
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Term
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Definition
| spreading factor that affects the ability of the pathogen to penetrate the tissue of the host by hydrolyzing hyaluronic acid- (breaks down barriers) |
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Term
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Definition
| spreading factor that breaks down collagen in muscle |
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Term
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Definition
| break down fibrin- dissolves clots formed by body to isolate infection |
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Term
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Definition
| splits urea to form ammonium hydroxide- raises pH of urine to make environment more conducive to bacterial growth. |
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Term
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Definition
| *promotes the formation of kidney stones. *promotes colonization of stromach (helicobacter) --> leads to gastric ulcers |
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Term
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Definition
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Term
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Definition
1. active portion is lipid A
2. induce fever, hypotension, shock, death
3. initiates complement cascade
4. activate B lymphocytes
5. stimulate production of tumor necrosis factor, interleukin-1, and prostaglandins
6. |
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Term
| True or false: the site of action for EXotoxins is more localized than ENDotoxins |
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Definition
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Term
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Definition
1. A-B exotoxins
2. membrane-active exotoxins
3. super-antigens |
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Term
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Definition
*have an A and B subunit--
1. the B subunit is associated with binding specificity
2. A portion determines mechanism of action |
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Term
| Examples of A-B exotoxins |
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Definition
1. neurotoxins--tetanus
2. cytotoxins--diptheria (inhibits protein synthesis)
3. enterotoxins--have activity at level of intestines |
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Term
| Membrane active exotoxins: |
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Definition
| Act directly on a cell's surface to lyse or kill |
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Term
| Examples of Membrane-active exotoxins |
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Definition
1. leukocidins--damage membranes of neutrophils and macrophages
2. lecithinase--enzyme destroys plasma membranes (esp. RBC)
3. hemolysins--destroy RBC and other cells by producing pores in membranes (cleave off phosphate head in phospholipid bilayer) |
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Term
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Definition
*bacterial proteins that bind the MHC class II on antigen-presenting cells and T-cells
*Results in the release of high levels of interleukin-2 which leads to release of other cytotoxins--leads to shock and death |
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