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IAHI Block 2 > Bacterial Toxins > Flashcards

Bacterial Toxins Flashcards

1
Q

Saprophytes

A
  • Organism that is not associated with disease
  • Free living bacteria
  • Most bacteria - Bacillus spp.
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2
Q

Commensals

A
  • Organims that live in association with a host
  • Relationship benefits both organisms
  • Most bacteria that live within a host - Staphylococcus
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3
Q

Opportunistic pathogens

A
  • Organism that causes disease in a compromised host: immune, physical, or chemical - Pseudomonas Staphylococcus
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4
Q

Pathogen

A

Organism that is capable of causing disease in a “normal host” - Bacillus antracis, Corynebacterium diptheriae

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5
Q

Virulence

A

Degree of pathogenicity

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6
Q

4 final outcomes of bacterial infection

A
  1. Death
  2. Recurrent illnesses
  3. Recovery and cure
  4. Asymptomatic Infection

* As number of bacteria increase, likelihood of death increases

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7
Q

Properties of a successful pathogen (4)

A
  1. Gain access into the host
  2. Colonize host tissue
  3. Resist host defense mechanism
  4. Damage host
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8
Q

Two mechanisms of pathogenesis

A
  1. Invasiveness
  2. Toxigenicity
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9
Q

Pathology due to the invasive properties of a bacterium

A

Microbe enters, colonizes, and grows in the host; damage is due to the growth of bacterium in the host

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10
Q

Pathology due to toxins produced by the bacterium

A
  • Microbe enters, colonizes, and grows in the host, typically at a specific site in the host (non-invasive)
  • Bacteria produce proteins that damage at sites distanced to site of infection
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11
Q

Toxoid

A

A substance that has been treated to destroy its toxic properties but retains the capacity to stimulate production of antibodies, used in immunization

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12
Q

General properties of bacterial exotoxins (7)

A
  • Produced by both gram positive and gram negative bacteria
  • Heat labile
  • Immunogenic → anti-toxin antibodies can neutralize toxin
  • Immunogenic → converted to a toxoid by chemical treatment to generate a vaccine
  • Mode of action does not include fever in host
  • Toxic at microgram amounts
  • Often responsible for entire pathology of pathogen
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13
Q

Four classes of bacterial toxins

A
  1. Surface-acting toxins - bind to receptor
  2. Pore-forming toxins - form channel to release nutrients from host cell
  3. A/B toxins - A component is enzymatic; B component is for binding
  4. Type III and IV secretion - paralyze host cell to prevent phaogocytosis of the pathogen
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14
Q

Toxins are ______ that are enzymes that modify specific host __________

A

Proteins; macromolecules

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15
Q

Modifications from Diptheria toxin and Pseudomonas aeruginosa exotoxin A:

A

ADP-ribosylate EF2: inhibits protein synthesis

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16
Q

Modifications from Botulinum toxin and Tetanous toxin:

A

Protease for SNARE proteins

17
Q

Modifications from Large clostridium difficile toxins:

A

Glucosylate Rho proteins

18
Q

Modifications from Shiga toxin:

A

Deadenylate adenine on RNA

19
Q

Protoxins

A
  • Bacteria secrete toxins in a protoxin form that is stable to the environment, but not active until protein has been modified
  • Activation by proteolysis, disulfide bond reduction
20
Q

Today’s application of Diptheria:

A

Vaccine - formalin inactivated diptheria toxin

Carrier - for conjugate vaccines (Hib) - CRM 197 a point mutation within DT that inactivates toxin

21
Q

Entry of diptheria toxin into eukaryotic cells

A
  • Diptheria toxin inhibits protein synthesis: ADP-r-EF2
  • Pathology within the heart, liver, lung, and nervous system
  • Death due to cardiac failure
22
Q

Diptheria, Tetanus, and Pertussis vaccines (4 combination vaccines)

A

Four combination vaccines: DTaP, Tdap, DT, and Td

DTaP and DT are given to children < 7yrs

Tdap and Td are given to older children and adults

23
Q

Children should get __ doses of DTaP at __, __, __, and __ - ___ months of age and __ - ___ years

A

5; 2; 4; 6; 15-18; 4-6

24
Q

___ does not contain pertussis, and is used as a substitute for DTap for children who cannot tolerate pertussis vaccine

25
Q

WHen should women recieve additional Tdap

A

During each of their pregnancies

26
Q

Adolescents 11-18 years of age and adults 19 and older should recieve a single dose of ____

27
Q

Major catalysts for Russian diptheria outbreak in 1990s

A
  • Increased proportion of susceptible individuals in the population due to migration of the population
  • A deteriorated health infrastructure (vaccination programs)
28
Q

what does the “a” in DTaP and Tdap stand for?

A

acellular - pertussis component contains only a part of the pertussis organism

IAHI Block 2 (12 decks)

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