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Microbiology

Ch. 15

TermDefinition
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
Created by: yulissalira