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VP - Microbio > Wk 9 > Flashcards

Wk 9 Flashcards

1
Q

What are the two choices of diagnostic method?

A

Detection of the agent and detection of host immune response

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2
Q

What are the four ways you can go about the detection of the agent?

A

Direct detection of the bacteria, phenotypic characteristics, molecular techniques to detect bacterial DNA , and immunological techniques

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3
Q

What are the two ways you can go about the detection of the host immune response?

A

Serology & detection of cell mediated immunity

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4
Q

What is direct microscopic observation? What characteristics would you look at?

A

Exam of stained or untrained preparations under microscope
Characteristics: density, morphology, cellular reactions

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5
Q

What types of bacteria require oxygen for growth?

A

Aerobes, microaerophiles, capnophiles

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6
Q

What types of bacteria do not require or uses oxygen for growth?

A

Anaerobes, aerotolerant anaerobes

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7
Q

What type of bacteria doesn’t require oxygen but can still use it for growth?

A

Facultative anaerobes

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8
Q

Define pure colony.

A

A single colony isolated from the rest of the colonies using the streak plate method

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9
Q

List the three types of microbial growth medias.

A

General purpose media, selective media, differential media

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10
Q

What is general purpose culture media? What molecules can you find on the plate? List examples

A

Def: supports growth of a wide range of non-fastidious bacteria
Molecules: C source (glucose), water, salts, source of amino acids and nitrogen
Examples: nutrient agar, TSA (TRYPTIC SOY AGAR)

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11
Q

What is selective culture media? What molecules can you find on the plate? List examples

A

Def: favors growth of specific organisms by restricting the development of other undesired bacteria
Molecules: abx, chemicals, indicator dyes, pH
Ex: mannitol salt (staphylococcus), macconkey (G-)

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12
Q

What is differential culture media? What molecules can you find on the plate? List examples

A

Def: discriminate one type of bacteria from others growing in the same medium
Molecules: biochemical reaction w indicator dyes
Ex: macconkey (lactose fermentation), blood agar (hemolysis)

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13
Q

Define unculturable.

A

Bacteria that are not grown on artificial media til date

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14
Q

Define serotype.

A

Group of related microorganisms distinguished by a common set of antigens; immunological ID of surface antigens on pathogens

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15
Q

What are some immunological techniques used to detect the agent?

A

Serotyping, Antigen detection (Fluorescent antibody staining, ELISA, Agglutination tests), chemical detection (analysis of total fatty acid/proteins), biological detection (LAL reacts with LPS)

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16
Q

Define serology.

A

Diagnostic identification of antibodies in serum; detection of humoral immunity

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17
Q

T/F: evidence of exposure to an infection agent does confirm an ecological role for that agent in the animal sampled

A

False. It does necessarily confirm that. Collect 2 serum samples 2 weeks apart and a 4 fold rise of antibody tiger are indicative for recent exposure to an infectious agent.

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18
Q

What is seroconversion?

A

Antibody development after exposure to a pathogen or antigen

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19
Q

What is an antibody titer? How is it expressed?

A

Measurement of antibody level (quantity).
Expressed as the reciprocal of the highest dilution of serum that positively reacts in a specific test

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20
Q

The higher the antibody response, the ________ the titer. In an example, a titer of 1280 means what?

A

Higher
Means that the serum sample remains + when diluted 1:1280

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21
Q

What are the two examples of cell mediated immunity techniques?

A

Tuberculin skin test, interferon gamma release assay

22
Q

What are other methods of sterilization that doesn’t fit into the criteria?

A

Acidification (pH <5.6)
Increased osmotic pressure (salt, sugar)
Oxygen removal (affects only aerobes)
Chemical additives

23
Q

Define sterilization

A

Process to eliminate or kill all forms of living microorganisms and their pathogenic products (including spores), usually on equipment and for surgical procedures

24
Q

Define anti microbial agent.

A

Drug that destroys microbes, prevents their multiplication or growth or prevents their pathogenic effect

25
Q

What is an antimicrobial?

A

Any substance of natural, synthetic, or semisynthetic origin that kills or inhibits the growth of microorganisms but causes little to no damage to the host.

26
Q

Define antibiotic

A

A low molecular substance produced by a microorganism that at a low concentration inhibits or kills other microorganisms

27
Q

T/F: all antibiotics are antimicrobials, but not all antimicrobials are antibiotics.

A

True

28
Q

What is the difference between natural v semisynthetic v synthetic

A

Natural: produced by bacteria or fungi (ex penicillin)
Semisynthetic: chemically altered natural compound (ex ampicillin)
Synthetic: chemically designed in the lab (ex marbofloxacin)

29
Q

What are four ways antimicrobials agents can be classified?

A

Type of antimicrobial activity, spectrum of activity, mode of action, and chemical structure

30
Q

What are five chemical structures antimicrobial agents can have?

A

Macrolide, tetracycline, beta lactams, aminoglycosides, sulfonamides/dipyrimidine

31
Q

T/F: in order to interfere with bacterial cell growth, antibacterial agents must interact with a vital structure or block a metabolic pathway and exhibit direct toxicity.

A

False; they exhibit selective toxicity

32
Q

For cell wall synthesis inhibitors, what is their mode of action? In terms of beta lactams, what type of bacteria is more susceptible to them?

A

MOA: inhibit peptide got an synthesis by binding to penicillin binding proteins, promote autolysin activity causing cell lysis
Gram +

33
Q

What is beta lactamase? List example of beta lactams

A

An enzyme produced by some bacteria that can cleave beta lactam ring and thus inactive them
Beta lactam: penicillin, ampicillin, cephalosporin, carbapenem, monobactam

34
Q

What are examples of protein synthesis inhibitors that inhibit the 30S subunit of bacterial ribosomes?

A

Aminoglycosides, tetracyclines

35
Q

What are examples of protein synthesis inhibitors that inhibit the 50S subunit of bacterial ribosomes?

A

Macrolides, chloramphenicol, lincosamides

36
Q

As a DNA synthesis inhibitor, what does quinolones do?

A

Inhibit enzymes which separate DNA strands (ex gyrase)

37
Q

As a DNA synthesis inhibitor, what does metronidazole do?

A

Causes breaks in DNA strands and is particularly effective against obligate anaerobic bacteria (ex clostridia)

38
Q

As a DNA synthesis inhibitor, what does rifampin do?

A

Inhibit RNA polymerase during transcription, active against mycobacterium tuberculosis

39
Q

As a DNA synthesis inhibitor, what does mupirocin do?

A

Inhibit tRNA synthetase during translation

40
Q

How can bacteria become resistant to DNA synthesis inhibitors?

A

Due to mutations in the gene encoding for enzyme DNA gyrase

41
Q

What are examples of folic acid syntheisis inhibitors? What is the difference between the two?

A

Sulphonamides - interfere with formation of folic acid, essential precursor for nuclei acid synthesis
Sulfonamides/trimethoprim - competitive inhibitors of dihydrofolate reductase (involved in DNA synthesis)

42
Q

What are two spectrums of activity?

A

Broad spectrum: active against both G- and G+ microorganisms
Narrow spectrum: limited activity and primarily only useful against particular species of microorganisms

43
Q

What is the difference between bactericidal and bacteriostatic agents?

A

Bactericidal: kill bacteria and reduce the total number of viable organisms
Bacterostatic: inhibit growth and replication of bacteria, thus host immune system to complete pathogen elimination

44
Q

T/F: if a type of therapeutic agent is not maintained at effective concentrations in the tissues, dissociation of the drug/cell structure complex can occur, permitting bacterial survival

A

True

45
Q

What are the three types of antimicrobial susceptibility testing?

A

Concentration gradient diffusion test, broth dilution, disk diffusion test

46
Q

What is antimicrobial susceptibility testing?

A

An in vitro test of the sensitivity of bacteria to one or more antibiotics by the diffusion technique on agar media

47
Q

What are the steps of disk diffusion test

A
  1. Bacteria is isolated in a pure culture
  2. Inoculate bacteria and spread on agar plate
  3. Place single concentration antimicrobial disks on plate and incubate
  4. Measure growth inhibition zone
  5. Compare to published reference breakpoints (zone size)
48
Q

What is the broth dilution test? Compare minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC).

A

Def: method for measuring minimum inhibitory concentration of antibiotics
MIC: highest dilution of an antibacterial agent that inhibits growth of an isolate
MBC: highest dilution of a drug that can kill a particular bacterium

49
Q

What is the concentration gradient diffusion test?

A

Method that uses diffusion and dilution to obtain MIC values at the point of intersection between the strip and the ellipse of the zone of inhibition

50
Q

What is the difference between innate resistance and acquired resistance?

A

Innate: preexisting genomic property
Acquired: acquired by mutation or horizontal gene transfer

51
Q

What are the four ways of antimicrobial resistance?

A

Inhibition of druguptake, activation of drug efflux pumps, inactivation of drug by enzymes, alteration of drug target

VP - Microbio (5 decks)

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