Chapter 15 - Microbial Mechanisms of Pathogenicity Flashcards
What are 4 ways bacteria damage host cells?
1) Using nutrients 2) direct damage in the vicinity of invasion 3) producing toxins 4) inducing hypersensitivity reactions
How do bacteria use a host’s nutrients?
Siderophores are proteins secreted by bacteria that take iron from iron transport systems.
How do cells cause direct damage to host cells?
As pathogens multiply, the host cell usually ruptures.
How do bacterial toxins damage host cells?
bacterial toxins can prohibit protein synthesis, destroy blood cells, and disrupt nervous systems.
What are the two types of toxins?
Endotoxins and Exotoxins
Write a brief note on exotoxins?
Exotoxins are enzymes released by bacteria that easily diffuse through the body. They inhibit strategic metabolic functions of the host. They cause specific symptoms for each disease.
What does disease specificity mean?
Exotoxins produce the specific signs of each disease
Write a brief note on endotoxins.
Endotoxins are lipopolysaccharides that are released from the cell wall of gram negative bacteria. They cause the over production and release of cytokines from T cells.
How does the body provide immunity to exotoxins?
antitoxins provide immunity against exotoxins.
What are toxoids and how are they beneficial?
toxoids are inactivated toxins, often by heat or chemicals . When injected into the body, they don’t cause disease but still stimulate the production of antitoxins.
How are exotoxins named?
1) the type of host cell attacked 2) the disease they are associated with 3) the bacteria that produces them
What are the 3 types of exotoxins?
1) A-B toxins 2) membrane-disrupting toxins 3) superantigen
Write a brief note on A-B toxins?
A-B toxins are composed of two polypeptide parts (an active and a binding part) invaginated by the host cell. The A part alters the function of the host cell and the B component is released for reuse.
Write a brief note on membrane-disrupting toxins. Include two examples.
Membrane-disrupting toxins cause the lysis of host cells by disrupting their plasma membranes. Two types of M-D toxins are 1) leukocidins (kill WBC) 2) hemolysins (Kill RBC)
Write a brief note on superantigens
superantigens are bacterial proteins cause the overproduction of T cells which gives rise to severe symptoms.
What is the effect of Diphtheria Toxin?
Diphtheria Toxins inhibit protein synthesis
What is the effect of Erythrogenic Toxins?
Erythrogenic toxins damage the plasma membranes of blood capillaries.
What is the relation between Endotoxins and Lipid A?`
Lipid A causes symptoms in a host after bacteria have been killed. Lipid A is the lipid portion of an endotoxin.
Apart from the overproduction and release of cytokines, what is a secondary effect of endotoxins?
Endotoxins cause the activation of blood clotting proteins which result in decreased blood supply.
How do aspirin and acetaminophen reduce fevers?
By inhibiting the synthesis of prostaglandins.
What is shock?
life-threatening decrease in blood pressure.
What is the term for bacterial induced shock?
septic shock?
What are R factors?
Plasmids that contribute to antibiotic resistance.
In addition to antibiotic resistance, how else can plasmids affect a microbe?
Plasmids can carry information that can contribute to pathogenicity and virulence
How does entry to a host cell contribute to host defense evasion?
Host defense cannot enter host cells
What is cytopathic effect?
The visible effects of viral infection
What are the three ways viruses can cause death?
1) multiplying in large numbers 2) affecting permeability 3) inhibiting synthesis
How do fungi cause disease?
Some fungal metabolic products are toxic, some secrete proteases,
How do Protozoa cause disease?
Protozoan waste products cause disease
How do helminths cause disease in their hosts?
Helminths cause cellular damage by using host tissue for their own growth or producing large parasitic masses
How do algae cause disease?
Algae produce neurotoxins
What are the most common portals of exit?
Respiratory and GI tract
