Chapter 25

Term
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entry of pathogen or parasite
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Terms in this set (83)
entry of pathogen or parasite
infection
have the ability to penetrate host defense
primary pathogens
primary pathogens also called
frank pathogens
cause disease only in compromised hosts
opportunistic pathogens
Things that can compromise a host
1. immune system defective (short term-tired) or long term
2. break in tissue allows organism access to new site
3. loss of other microflora allows organism to bloom (antibiotics)
Measure of the ability to cause disease
pathogenicity
What is the pathogenicity determined by
genetic make up
number of organism to colonize fifty percent of hosts
infectious dose =ID50
rate of lethal infections
virulence
number of organism to kill 50 % of hosts
lethal doze- LD50
inanimate objects or substance that can carry infections (door knobs)fomitestwo possible ways to spread an infectioncontact with fomites and horizontal trasmission via vectorsexample of infection spread using vectorsmosquitos - yellow fever malariavectors can be what for the disease organismreserviorsencodes factors allowing pathogen to invade host like toxins and attachment proteins and capsulesvirulence genessection of genome containing multipe virulence genes often related in functionpathogenicity islandsExamples of pathogenicity islandsprotein secretion system and toxin productionHow are pathogenicity islands transferredas a block from other organism6 steps of an infection1. exposure to pathogens 2. adherence to skin or mucosa 3. invasion through epithelium 4. colonisation and growth 5. toxicity or invasivness 6. tissue damage/ diseasestructures and characteristics of pathogens that allow them to cause diseasevirulence factorsability to adhere to mucus membraneadhesion3 factors affecting adhesioncapsule fimbriae/pilli/ adhesinsother polysaccharide layer helps bacteria in attachment protects them from phagocytosiscapsuleneccessary for some organism to attach like neisseria gohneria and ecolifimbriae/pillisurgace proteins bind host cellsadhesinsWhat must pathogens be able to penetrate to invadethe outer layer of skin cells the epitheliumHow do pathogens enter the inner layers of skin cellsthrough lesions or mucus membranesOnce the pathogen has invaded a host what can it now doreproducetwo antigens of salmonellao and vifor salmonella prevents phagocytosis, cell surface polysaccharideOcapsule antigen for salmonella prevents complement binding and antibody mediated killingVicompounds that bind iron and make it available to the bacterial cellsiderophoresS. aureus produuces this compound which lyses white blood cells and decreading host resistanceLeukosidinOrganisms grow locally at site of invasion in this kind of infectionlocalized infectionorganisms spread through body rising blood or lymphatic systemsystemic infectionMany virulence factors are what that can break down tissuesenzymesdestorys polysaccharides that hold animeal cells togetherHyaluronidaseWhat species produce Hyaluronidasestaph and streptobreaks down collagencollagenaseorganism producing collagenaseClostridiumbreaks down fibrin clotsStreptokinaseWhy are clots made by the hostto wall off bacterial infections and prevent the spread to healthy tissuesWhat makes streptokinasestreptococcus pyrogenesdisrupt cytoplasmic membranes of animal cells lyse RBCshemolysinscompounds produced by pathogens that damage host tissuestoxins3 major groups of toxinsexotoxins, enterotoxins, and endotoxinsproteins secreted by bacteria that can damage tissues far from infection siteexotoxinsWhat does diphtheria toxin inhibitprotein syntheseisdiphteria toxin is produced by bacteria that are lysogenized by what that carry watphage beta that carry tox genesWhat does tetnus toxin act onmotor neuronsWhat does the tetnus toxin causecontinual contraction of muscles and can lead to lockjawWhat does Clostridium tetani infectdeep woundsprecents muscle contraction results in respiratory or cardiac failurebotulinum toxinBotulism is caused by whatingesting the toxin not the bacteriaproteins that act on small intestine and cause diarrheaenterotoxinsWhat kind of organisms produce enterotoxinsfood poisoning organisms like clostridium e coli salmonellaWhat is Vibrio cholera produceCholera toxincauses secretion of massive amount of water into small intestine (diarrhea) death by dehydrationCholeraWhen gram - bacteria lyse, lipid A portion of LPS (lipopolysaccharide) is releasedendotoxinsWhich organisms produce toxic LPSE.coli salmonella and shigellaWhat symptoms do endotoxins causediarrhea,fever, vomitingWhich subunit of the AB toxin binds to the hostBHow is the A subunit of the AB toxin deliver to the cellby the B subunitHow many B subunits form a pore for A entry5What kind of toxicity does the A subunit havetoxicTwo toxins with ADP-RibosyltransferaseDiphtheria toxin an cholera toxinWhy does the cholera toxin ribosylateto overactivate adenylate cyclaseWhat happens with the cholera toxin when cAMP activates ion transportwater followsThe diphtheria toxin ribosylates...elongation factor 2What does the diphtheria toxin blockribosome function resulting in cell deathHOw do pathogens break out one ingested in the phagosomehemolysinTwo organisms that produce hemolysinShigella dysenteriae and Listeria monocytogenesTwo way pathogens surive the fusioin of the phagsome with the acidic lysosome1. secrete proteins to prevent fusion 2. mature in acidic environmentsTwo pathogens that secrete proteins to prevent the fusion of the phagosome with the acidic lysosomesalmonella and chlamydiaOne pathogen that matures in an acidic environmentCoxiella burnetii- Q feverFour things contributing to the flu viruses antigenic drift1. RNA polymerase does not correct replication errors 2. Frequent mutations in hemaglutinin gene 3. If mutation allows virus to avoid immune system 4. New flu vaccine needed every yearAs part of influenza antigenic shift, what two things can happen1. two strains infect host at same time 2. recombined viruses have mix of chromosomesExample of two strains of influenza virus infecting a host at the same timechicken or swineWhen the recombined flu virus has a mix of chromosomes what happens to the genesthere is an immediate alterationWhat caused the 1918 influenza outbreak (largest single year life loss)flu antigenic shiftHow does HIV avoid immunityby infecting immune cellsHow does HIV infect immune cellsbinds multiple receptors like CD4 and chemokine receptor CCR-5 (associated with T cell)What do the cells infected with HIV do to other immune cellsmisregulates them