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Microbiology
Ch. 15
Term | Definition |
---|---|
the ability to cause disease | Pathogenicity |
the extent of pathogenicity | Virulence |
What are the preferred portal of entry? | -mucous membranes -Skin -Parenteral route |
What are the three mucous membranes (portals of entry) | -respiratory tract -gastrointestinal tract -genitourinary tract |
infectious dose for 50% of the test population | ID |
lethal dose (of a toxin) for 50% of the test population | LD |
which portal of entry is most effective for the B. anthracis infection? | skin (10-50 endospores) |
Which toxin is most potent? | Botulinum (0.03 ng/kg) |
binds to receptors on host cells | Adhesins/ligands |
How do bacterial pathogens penetrate host defenses? | -capsules -cell walls components -enzymes |
How do capsules penetrate host defenses? | -prevent phagocytosis |
Can human bodies produce antibodies against some capsules? | yes |
True or false: nonpathogenic bacteria cannot produce capsules | false; many nonpathogenic bacteria produce capsules |
What is an adhesin that resists phagocytosis? | Streptococcus pyogenes M protein |
what is an adhesin to leukocytes where it can grow? | Neisseria gonorrhoeae Opa protein |
What is a waxy lipid that resists digestion by phagocytes? | Mycobacterium tuberculosis Mycolic acid |
enzyme that coagulates fibrinogen | coagulase |
enzyme that digests fibrin clots | streptokinase or staphylokinase |
enzyme that hydrolyzes hyaluronic acid | hyaluronidase |
enzyme that hydrolyzes collagen | collagenase |
enzyme that destroys IgA antibodies | IgA proteases |
Salmonella alters host actin to enter a host cell | Invasins |
How do bacterial pathogens damage host cells? | -by using the host's nutrients -by causing direct damage -by producing toxins -by inducing hypersensitivity (allergy) reactions |
-use the host cell for nutrients -produce toxic waste products -cell rupture after intracellular growth | direct damage |
true/false: most damage by many bacteria is done by toxins | true |
substance that contributes to pathogenicity | toxin |
ability to produce a toxin | toxigenicity |
presence of toxin in the host's blood | toxemia |
inactivated toxin used in a vaccine | toxoid |
antibodies against a specific toxin | antitoxin |
exotoxins are ____ and many are ______. *exam 3* | proteins; enzymes |
exotoxin genes are carried usually by what? *exam 3* | plasmids or phages |
exotoxins are produced by mostly what?*exam 3* | G(+)s |
Lyse host's cells by *exam 3* | -making protein channels in the plasma membrane or membrane disruption -disrupting phospholipid bilayer |
superantigens are produced by what? *exam 3* | bacteria |
what bind host immune cells (T cells) for a long time? *exam 3* | superantigens |
What happens when superantigens bind host immune cells (T cells) for a long time? *exam 3* | host immune cells produce too much cytokine |
too much released cytokines does what? *exam 3* | provoke a very intense immune response |
too much released cytokins/ provoking a very intense immune response causes what symptoms? *exam 3* | fever, nausea, vomiting, diarrhea, shock, and death |
do all endotoxins produce the same signs and symptoms, regardless of the species of microorganism? *exam 3* | yes |
any life-threatening decrease in blood pressure *exam 3* | shock |
shock caused by bacteria *exam 3* | septic shock |
shock caused by gram-negative bacteria *exam 3* | endotoxic shock |
viruses grow where components of the immune system cannot reach *exam 3* | inside host cells |
the visible effects of viral infection are known as what? *exam 3* | cytopathic effects (CPE) |
portals of exit *exam 3* | -respiratory tract -gastrointestinal tract -genitourinary tract -skin -blood |
2 major entry sites for microorganisms to enter a host | skin and mucous membranes (weaker, more vulnerable) |
easiest and most frequent mucous membrane (common cold, pneumonia, tuberculosis, influenza, measles) | respiratory tract |
mucous membrane that should overcome stomach acid, bile, and enzymes (typhoid fever, salmonellosis, cholera) | gastrointestinal tract |
mucous membrane thats a portal of STD (HIV infection, genital warts, chlamydia, herpes, syphilis, gonorrhea) | genitourinary tract |
portal of entry through openings in the skin (hair follicles, sweat gland ducts) | skin |
How is the degree of pathogen's virulence generally measured? | ID (50): infectious dose LD (50): lethal dose |
Which portal of entry is most effective for B anthracis infection? | skin |
Which toxin is most potent? | Botulinum (most potent toxin on earth) |
what bacterial molecules are used to bind to their host cells? | adhesin (ligand) |
what molecules are used as adhesins? | Glycocalyx, Fimbriae, M protein |
which microorganisms (m/o) uses dextran as an adhesin? | |
which E. coli cell surface appendage is used to bind to host cells? | Fimbriae |
M protein is used as an adhesion by what m/o? | |
Generally how do bacterial capsules avoid phagocytosis? | capsules make m/o watery, harder to grab |
How is M protein used to avoid phagocytosis? | M proteins bind to host cells and are not recognized by white blood cells |
How is the Opa protein used to avoid host immune attack? | bind to immune cell and can survive when engulfed by white blood cell |
How is mycolic acid used to avoid host immune attack? | waxy lipid= hard to digest |
what is the role of coagulase in bacterial pathogenesis? | makes blood clots |
what is the role of streptokinase and staphokinase in bacterial pathogenesis? | dissolve blood clots |
How does streptokinase dissolve blood clot? | digests fibrin (molecules that form clots) |
what is the role of collagenase in bacterial pathogenesis? | breaks down collagen (which keeps skin looking young, holds moisture) |
what is the role of invasins in bacterial pathogenesis? | enters host cell by sticking adhesins into host cell (hooks into host cell, host cell eats bacteria) |
invasins are what type of proteins? | cell surface proteins |
Intracellular pathogens such as listeria, shingella, and coxiella burnetii, how do they spread one host cell to another? | Use actin to propel themselves from one cell to the next |
actins can be protected by what? | antibodies |
why do both human hosts and pathogens need iron for living and how do pathogens steal host's iron? | iron carries oxygen; steal transport proteins (that carry iron |
what is the function of siderophores and what produces them | iron binding molecules that steal iron from iron proteins; bacteria produces them |
how do pathogens damage host cells directly? | -use host cell for nutrients -produce toxic waste products -cell rupture after intracellular growth, some bacteria penetrate host cells by excreting enzymes and by their own motility |
how can toxiods prevent microbial infections? | used in vaccines, which then give immunity to disease |
definitions of exotoxins and enotoxins? | exotoxins: toxic substances released outside the cell endotoxins: toxins composed of lipids that are part of the cell |
which molecule is the endotoxin and which one gram negatives or positives have it? | Lipid A/ gram negative |
endotoxins are ______ produced by _______ bacteria. | lipopolysaccharides; gram negative |
what is not an advantage of being intracellular pathogens? | they can produce toxin more easily |
How does actin differ from invasin? | actin is used to go from one cell to another, while invasin is used to invade one cell |
toxoids are what kind of toxins? | inactivated toxins |
acts as cement so white blood cells cannot attach to bacteria | hyaluronidase |
breaks down collagen | collagenase |
many bacterial products are used for medical purposes. In the case of the disease shown in the picture, what bacterial product can be used? | streptokinase (breaks down blood clots) |
*exam 3* what are characteristics of exotoxins? | -unique structure and function -genes carried by plasmids or phages -produced by mostly G(+)s |
*exam 3* Exotoxins are divided into 3 principle types on the basis of their structure and function. What are those? | A-B toxins, membrane-disrupting toxins, superantigens |
what is the definition of A-B toxins? | 2 subunits: A component- active, possesses toxin activity B component- binding, attaches to host cell receptor |
*exam 3* what do hemolysins do? | kill red blood cells |
*exam 3* what do leukocidins do? | kill white blood cells |
*exam 3* how does streptolyin O disrupt red blood cells? | break the red blood cell and release the iron |
*exam 3* What is the function of superantigens in bacterial pathogenesis? | bind host immune cells (T cells) for a long time --> host immune cells produce too much cytokine |
*exam 3* what is the molecular component of exotoxins? | proteins |
*exam 3* endotoxins generate what? | fever |
*exam 3* what is Phage Conversion? | lysogenic cycle |
*exam 3* what is the signaling mechanism for muscle contraction? | the brain |
*exam 3* what is the role of botox? | to prevent wrinkle formation (from botulinum toxin) |
*exam 3* how does botulinum toxin work? | blocks the release of acetocoline inhibiting contraction |
*exam 3* What is the name of tetanus toxin? | tetanospasmin |
*exam 3* how does tetanospasmin work? | binds to inhibitory interneurons preventing release of glycine and relaxation of muscle |
*exam 3* how does cholera toxin work and what is the result? | (A-B toxin) pulls the ions out of intestinal tract; gives severe diarrhea |
*exam 3* in an A-B toxin, B delivers toxin A by doing what? | binding to a receptor |
*exam 3* what is the chemical nature of endotoxins? | lipids |
*exam 3* how do endotoxins cause fever? | trigger immune response, release of cytokines, inflammatory process (pyrogenic response) |
*exam 3* Endotoxins or exotoxins don't always cause fever? | exotoxins (depends on the exotoxin) |
*exam 3* what are the benefits for microorganisms to grow inside host cells? | they hide from immune system, get lots of nutrients, if they infect white blood cells, then they can go to any part of the body |
*exam 3* portal of exit example: coughing and sneezing | respiratory tract |
*exam 3* portal of exit example: feces | gastrointestinal tract |
*exam 3* portal of exit example: urine and vaginal secretions | genitourinary tract |
*exam 3* portal of exit example: arthropods, needles or syringes | blood |
*exam 3* which hormone is produced by the endotoxin and causes fever? | prostaglandins |