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40 Cards in this Set
- Front
- Back
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Define pathogenicity.
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The qualitative ability to cause a disease by overcoming the defenses of the host
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Define virulence.
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The extent of a microorganism's ability to cause a disease
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Define Pathogenesis.
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The origin and development of a disease
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List the steps of a pathogen's invasion of a host.
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Exposure, Adherence, Invasion, Colonization and Growth, Toxicity, Invasiveness (further growth), Tissue damage and disease
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List 3 ways virulence can be expressed.
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1. The number of cells required to kill the inoculated host
2. LD50: Lethal dose for 50% of the inoculated hosts 3. ID50: Infectious dose for 50% of the inoculated hosts |
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List some portals of entry for microorganisms.
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Conjunctiva: a membrane that covers the sclera (the white part of eye)
Respiratory tract: Most common Gastrointestinal tract and Genitourinary tracts |
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Adhesins on pathogens can be what types of proteins?
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Glycoproteins or lipoproteins (and are often associated with fimbriae)
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What is the most common host receptor?
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Mannose
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What provides attachment and resistance to antimicrobial agents?
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Biofilms (a structure made of microbial cells and extracellular polymeric substance)
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How do capsules help bacterial pathogens to penetrate host defenses?
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Capsules prevent them from being phagocytized
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How do proteins in some bacterial pathogen's cell walls assist them in penetrating the host's defenses.
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They can facilitate adherence and prevent them from being phagocytized
(ex: M protein of S. pyogenes: cell surface and fimbriae) |
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Some microbes can reproduce inside phagocytes. Give one example from the powerpoints.
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M. tuberculosis
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What is the "parenteral route"?
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A microorganisms route through a barrier such as injections, bites, cuts, wounds, surgery, etc
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What are membrane-disrupting toxins that kill phagocytic leukocytes (namely neutrophils and macrophages)?
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Leukocidins
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Name the bacterial enzyme that protects local infections in a fibrin clot.
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Coagulase (some members of the genus Staphylococcus produce coagulase)
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List 3 bacterial enzymes that help an infection spread.
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1. Kinases: break down fibrin and thus digest clots formed by the body
2. Hyaluronidase: hydrolyzes hyaluronic acid, a polysaccharide that holds certain cells together 3. Collagenase: breaks down collagen which forms muscle and and other body organs and tissues |
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Salmonella bacteria produce invasins, what function do they serve?
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Invasins cause the actin of the host cell's cytoskeleton to form a basket to carry the bacteria into the cell.
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Name three ways bacteria obtain iron from their hosts.
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1. Siderophores: iron binding proteins
2. Receptors: bind to iron transport proteins 3. Toxins: kill cells and the iron is released |
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Define toxemia.
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The presence of toxins in the blood
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Define Toxoid.
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Heat or chemically inactivated toxin: antigenic properties are preserved but disease causing abilities are destroyed
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What are A-B toxins?
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A type of exotoxin made of 2 polypeptides, A & B
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What are the two membrane-disrupting toxins and what do they do?
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Leukocidins: an exotoxin that kills phagocytic leukocytes
Hemolysins: an exotoxin that kills RBCs |
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Are endotoxins found in Gram negative or Gram positive bacteria?
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Gram negative
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What are endotoxins made of?
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Lipopolysaccharides (LPSs), a component of the cell wall of gram negative bacteria
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How are endotoxins released from the gram negative bacteria's cell wall?
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Antibiotics and/or antibodies can cause cell lysis, releasing the endotoxins; they can also be released during bacterial multiplication
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What consequences do endotoxins cause?
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Fever, shock, chills, weakness, generalized aches, sometimes death; they can also be responsible for miscarriages; they also allow bacteria to cross the blood-brain barrier
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The Lipopolysaccharides (LPSs) that make up endotoxins is also called what?
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Lipid A
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What is used to detect endotoxins in drugs and on medical devices?
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Limulus amoebocyte lysate (LAL) assay; from the white blood cells of the horseshoe crab
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Contrast the make up of endotoxins vs. exotoxins.
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Endotoxins are made of lipopolysaccharides and exotoxins are made of proteins
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How do viruses avoid the host's immune system?
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By growing inside host cells
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How do viruses gain access to host cells?
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Viruses have attachment sites for receptors on the host cell
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What are visible signs of viral infections called?
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Cytopathic effects (CPE)
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What are cytocidal effects and noncytocidal effects?
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Cytocidal effects: cell death
Noncytocidal effects: cell damage but not death |
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Name 7 cytopathic effects (visual sings of viral infections) of viruses.
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1. Stopping of mitosis 2. Lysis 3. The formation of inclusion bodies (granules in the cytoplasm or nucleus) 4. Cell fusion 5. Antigenic changes 6. Chromosomal changes 7. Transformation (more info on p. 442 of text)
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What causes the symptoms of fungal infections?
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Capsules, toxins and allergic responses
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What causes the symptoms of protozoan and helminthic (parasitic worms) diseases?
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Damage to host tissue or their metabolic wastes
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How do some protozoa avoid being killed by the host's antibodies?
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They change their surface antigens; example the Trypanosoma can make up to 1000 different antigens to stay ahead of the bodies defenses (p. 444 of text)
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What do some genera of dinoflagellates (an algae) produce and how is it pathogenic to humans?
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Neurotoxins; cause paralytic shellfish poisoning (Red Tide) and ciguatera (food poisoning) when ingested by humans
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List three common portals of exit of pathogens.
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1. Respiratory tract
2. Gastrointestinal tract 3. Urogenital tract |
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What is a portal of exit for microbes in the blood?
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Arthropods and syringes
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