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MICROBIOLOGY: CMOD-Week 1 > Micro Extras from Lecture > Flashcards

Micro Extras from Lecture Flashcards

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1
Q

Differentiate between mycoplasma and mycobacteria?

A
  • Mycobacteria have a mycolic acid outer coat that is acid-fast staining
  • Mycoplasma have a membrane made of sterols and are often too small to see with a light microscope
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2
Q

Bacteria that cause meningitis typically have a feature that prevents phagocytosis, what is this feature?

A

Capsule

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3
Q

Where is the H antigen found?

A

Flagella, for motility

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4
Q

What is the K antigen found?

A

Capsule, antiphagocytic

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5
Q

Where is the O antigen found?

A

LPS endotoxin

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6
Q

What is a Peptioglycan?

A

Polysaccharide joined by peptide chains

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7
Q

Which uses 5 glycines to cross-link their peptidoglycan outer membrane?
- Gram (-) or Gram (+)

A

Gram (+) bacteria

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8
Q

Which of the following do obligate anaerobes NEVER have?

a. Catalase
b. Peroxidase
c. Pyruvate Kinase
d. Superoxide Dismutase

A

D. superoxide dismutatse

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9
Q

T or F: antiviral drugs require that we target our own cells

A

True

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10
Q

Although antimicrobials are designed to attack ONLY prokaryotic species, there is a target in humans that behaves much like a bacteria, what is it?
- which drugs would you expect to affect it the most?

A

Mitochondria

  • Drugs that work on protein and DNA synthesis
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11
Q

Where are ß-lactamases located in gram (+) and gram (-) bacteria?

A

Gram (+) ß lactamases exist extracellularly

Gram (-) ß-lactamases are in the PERIPLASM

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12
Q

Name 3 types of endotoxin.

- what do high levels of this in the blood cause?

A
  • Lipoteichoic acid, Teichoic acid, LPS
  • Can cause SEPTIC SHOCK

**REMEMBER IF THERE ARE HIGH LEVELS OF ENDOtoxin IN THE BLOOD THEN THERE MUST ALSO BE BACTERIA IN THE BLOOD

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13
Q

Why do capsules serve as antiphagocytic structures?

A
  • They cover PAMPs but the complement system still works
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14
Q

Why are lysozymes so effective at ruining cell walls?

A
  • They cleave the NAM-NAG disaccharide into two monosaccharides
  • These can’t be put back together because transglycosylases only deal with the disacharride as a unit
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15
Q

T or F: looking at the change in turbidity of a solution before and after application of an antibiotic will indicate whether the drug is bactericidal or bacteriostatic

A

False, even if its a bactericidal drug the turbity of the solution will level off and stay constant past the point where the antibiotic was applied

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16
Q

What the best way to get rid of a biofilm?

A

Remove the foreign object that is causing it

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17
Q

What does lactoferrin do?

A

Depletes availability of iron to bacteria

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18
Q

A nose swab indicates that a person has MRSA, however they experience no symptoms from the bacteria’s presence. Is this an infection or colonization?

A

Colonization

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19
Q

Why is it not uncommon to see a bacterial infection accompanying the flu?

A
  1. Has nuraminidase as a virulence factor the cleaves sialic and and makes it easier for bacteria to attach to cell membrane
  2. Kills ciliary cells of the lungs preventing them from sweeping the mucous out
  3. Inhibits chemotaxis and neutrophils
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20
Q

Why with a latent infection like Hep B do tests indicate that the virus is less abundant during an acute attack?

A
  • The immune system won’t detect the virus unless it begins to replicate thus it can exist at higher concentration in the tissue without being attacked
21
Q

How do each of the following escape the wrath of the phagosome?

  • Shigella
  • MTB
  • Salmonella Typhi
A

Shigella:
- escapes phagosome before lysosome binds

MTB
- Prevents lysosome binding

Salmonella Typhi
- Keeps lysosome from lowering the pH too much

22
Q

How does strep turn into Rheumatic Fever?

A

Strep releases M protein that binds to human cells and makes out immune cells attack our own bodies

23
Q

You eat some bad food and get sick 4 hours later, what caused the sickness?

A
  • Toxin from bacteria that had already been produced on ingestion
  • if the symptoms had taken longer to manifest it likely would have been the actual bacteria causing the problem
24
Q

What happens if you event an antibiotic that has an MIC of 3 but has a breakpoint of 2.7?

A

You will never be able to use this drug because the minimum concentration needed to be effective is greater than the maximum concentration that can be achieved in the blood.

**A good drug has a breakpoint that is several times greater than its MIC

25
Q

**If a bacteria is resistant to multiple drugs, all of which have different MOA, then what would you expect its method of resistance is?

A

MDR efflux pump

26
Q

What opportunistic infection often arises as a result of using Clindamycin?

A

C. Diff

27
Q

What do you expect to happen to the MIC after an antibiotic has been on the market for 20 years?

A

It will likely rise do to positive selection for resistant bacteria

28
Q

T or F: if a bacterium is resistant to one drug is much more likely to be resistant to another drug even if the MOA is different.

A

True

29
Q

Categorize the following resistances:

  • MRSA
  • VRSA
A

MRSA: codes for a different (less efficient) transpeptidase

VRSA: target is altered from D-Ala D-Ala to D-Ala D-Lac

30
Q

Why would you double treat someone who comes in with an STD with ceftriaxone and azithromycin?

A

Ceftriaxone also covers for the possibility that the patient also Chlamydia

31
Q

How are experiments conducted to determine the MIC and MBC of a drug?

A
  1. you add the same microorganism to tubes that have been serial diluted with an antibiotic (all tubes are clear)
  2. The tube are incubated and turbidity is measured, the lowest concentration where no change in turbidity is seen = MIC
  3. Starting with the concentration of the MIC up to higher antibiotic concentrations are then plated
  4. The one with the lowest concentration that doesn’t grow any bacteria = MBC

**see slide 15 Joint Lect 2

32
Q

What is an inducer?

- what is the inducer in the lac operon?

A

Inducers can act in two ways depending on what they bind:
a. Binds an Activator Protein (positively regulated system) then it will cause promotion of RNA polymerase transcription

b. Bind a Repressor Protein (negatively regulated system) then it will prevent repressor from binding and RNA polymerase will be able to proceed.

**Allolactose acts as the inducer in the negatively regulated Lac Operon

33
Q

Give the steps of Two component signalling.

A
  1. Sensor (transmembrane) binds its ligand and autophosphorylates itself
  2. Transducer get phosphorylated, then heads to the nucleus to up regulate gene expression

Commonly used in quorum sensing

34
Q

Describe in detail why infections by Neisseria Gonorrheae can be Recurrent if pilli serve as the primary target for combating the bacteria.

A
  • Code for the pilli of N. Gonorrheae is located at two loci
    1. pilE Expression Loci that consists of a conserved region and a Variable region
  1. pilS Silent Loci is a loci that:
    - lacks promoters
    - Consists of Several variations of the same gene (isotypes)
    - These Isotypes are only expressed with recombined into Variable region of pilE
35
Q

T or F: Transposons serve as mutagens inside the cell

A

True, Transposons must confer some selective advantage (antibiotic resistance etc.) in order to be passed on

36
Q

T or F: plasmids contain genes essential to cell survival

A

False

37
Q

How does Hfr transfer occur?

A
  • When F factors transfer parts of the Donors Genome (NOT PLASMID)
  • This occurs only the F factor has integrated into the bacterial Chromosome
  • F factor will initiate transfer and drag chromosomal genes DOWNSTREAM of the F factor into the other cell

Most Effective way for a bacteria to Transfer large amounts of Genetic Material*

38
Q

How do you know that a bacteria has gotten a gene via generalized transduction and not specialized transduction?

A

Generalized:

  • Suppose a bacterium gets a resistance gene via Generalized Transduction, it would have a selective advantage but if you isolated the virus from that bacterium the resistant gene would not come with it.
  • Your results would not be repeatable, furthermore ONLY VERTICAL transfer of genes could occur. (this is highly unlikely b/c the virus would likely kill the bacteria that acquired the gene prior to replication)

Specialized:

  • You could isolate the phage and make new resistant bacteria all day
  • IT CAN BE HORIZONTALLY TRANSFERRED AND ITS REPEATABLE SO ITS MORE IMPORTANT TO CREATING GENETIC DIVERSITY
39
Q

T or F: cholera toxin is found on a temperate phage.

A

True

40
Q

T or F: an opportunistic pathogen may occasionally cause disease in immunocompetent people.

A

False, bugs like the one described fall somewhere between frank and opportunistic (e.g. Strep A)

41
Q

What is an example of a pore forming toxin?

A

Hemolysins

42
Q

What caused toxic shock from tampons in the 80s?

A

Staph Aureus got into cotton and reproduced, meanwhile it released super-antigen that binds to MHC II and causes cytokine storm (even without co-stimulatory signaling)

43
Q

What is the role of protein M?

A

Similar to Protein A it is antiphagocytic

44
Q

What are some defining characteristics of recurrent infections?

A
  • Many Different Antigenic Determinants

- May be latent or intracellular, thus able to evade host defenses and come and go as it pleases

45
Q

What are anti-toxins?

- toxoids?

A 
Anti-toxins = antibodies formed to bind and neutralize a toxin
Toxoids = inactivated toxin that can be injected for immunization
46
Q

T or F: someone with neutropenia is likely more susceptible to a fungal infection than someone with a B cell deficiency.

A

True, neutrophils are the primary fighters against fungus, neutropenia = high risk factor

  • Also T cells help a lot and cause many of the symptoms associated with it.
47
Q

Where all can ring worm manifest?

A 
Barbare - Face
Captitis - scalp
Corporis - body
Cruris - jock itch
Pedis - foot
48
Q

T or F: histoplasmosis causes granuloma formation.

A

True, it takes up resisidence in macrophages

49
Q

What form does Candida ALWAYS take?

A

Yeast

MICROBIOLOGY: CMOD-Week 1 (10 decks)

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