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Microbio Exam 1 > antibiotics 4 > Flashcards

antibiotics 4 Flashcards

1
Q

Selective toxicity of antibiotics

A

Killing or inhibiting microorganism without harming host cells

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2
Q

Bacteriostatic

A

Inhibit growth

Used when host defenses can be counted on

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3
Q

Bactericidal

A

Killing bacteria

Used during invasive infection or with immunocompromised patient

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4
Q

Antibiotic synergism

A

Combination of two antibiotics that enhance antibacterial activity when used together

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5
Q

Antibiotic antagonism

A

Combo of antibiotics where one interferes with the other

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6
Q

Broad-spectrum antibiotics

A

Effective against a large variety of bacteria

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7
Q

Advantage of broad-spectrum antibiotics

A

Increase likelihood of effectiveness against bacterial infection of unknown etiology

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8
Q

Disadvantage of broad-spectrum antibiotic

A

Increased likelihood in disrupting patient’s normal microbiota

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9
Q

Narrow-spectrum antibiotics

A

Effective only against a small subset of bacteria

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10
Q

Narrow-spectrum antibiotic advantage

A

Avoids disruption of normal microbiota

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11
Q

Narrow-spectrum antibiotic disadvantage

A

Must know the specific bacteria and its resistances

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12
Q

Do antibiotics cause resistance?

A

No - acquisition of genetic information may result in resistance

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13
Q

What do antibiotics do, as far as selection against bacteria?

A

They select against sensitive bacteria, and select for resistance bacteria

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14
Q

Antibiotic resistance categories

A

Sensitive (S)
Intermediate (I)

Resistant (R)

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15
Q

(S) bacteria

A

Infection can be treated with recommended antimicrobial agent

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16
Q

(I) bacteria

A

Infection can be treated where high dose is able to be used

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17
Q

(R) bacteria

A

These isolates will not be inhibited by the usually achieved concentrations of the antimicrobial agents

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18
Q

Empiric therapy

A

Used while waiting for lab results - generally broad-spectrum

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19
Q

Targeted therapy

A

Refined treatment - narrow-spectrum

20
Q

Antibiotic prophylaxis

A

Prevent rather than treat disease

Used with immunocompromised patients, or exposure to high-risk pathogens

21
Q

Mechanisms of antibiotic resistance

A

Breakdown of antibiotic (hydrolysis)
Chemical modification of an antibiotic

Alteration of the target

Altered permeability (decreased influx or increased efflux)

Lack of target

22
Q

Minimum inhibitory concentration (MIC)

A

Lowest concentration of antibiotic that inhibits growth

23
Q

Minimum bactericidal concentration (MBC)

A

Lowest concentration of antibiotic that kills 99.9% of bacteria

24
Q

Kirby-Bauer Test

A

Disk-diffusion assay

Disks of antibiotic on agar plate to see what antibiotic is most effective

25
Q

E-test

A

More recent development where you read the lines on a strip of antibiotic
Can determine MIC easier than disk-diffusion test

26
Q

Broth culture

A

Overnight incubation
Can determine MIC using optical density of test tubes

Can determine MBC by measuring remaining bacteria on a plate

27
Q

Cell wall synthesis inhibitors are specific for?

A

Peptinoglycan

28
Q

Cell wall active antibiotics

A

Only disrupts actively dividing bacteria by disrupting peptinoglycan synthesis

29
Q

Membrane active antibiotics

A

Disrupts or interferes with membrane integrity/synthesis

Effective against resting and actively dividing bacteria

30
Q

Beta-lactams

A

Bactericidal
Inhibition of cell wall synthesis

Ex. penicillins, cephalosporins, etc.

31
Q

Beta-lactam mechanism - step one

A

Penicillin binding protein binds to pentapeptide chain of peptidoglycan

32
Q

Beta-lactam mechanism - step two

A

Reactive serine will cleave Ala (position 5 of pentapeptide chain)

33
Q

Beta-lactam mechanism - step three

A

Generation of pentaglycine chain to bind two peptidoglycan chains

34
Q

Beta-lactam mechanism - step four

A

Penicillin binds to penicillin binding protein and blocks its active serine

35
Q

Beta-lactam mechanism - step five

A

Penicillin binding protein is inactive, and peptidoglycan chains cannot be expanded

36
Q

Beta-lactam resistance

A 
Altered transpeptidases (decreased affinity to antibiotic)
Altered outer-membrane permeability (mutation in porins)

Presence of efflux pumps

Chemical modification of antibiotic (beta-lactamase)

37
Q

Vancomycin

A

Binds to the two D-Ala residues on the end of the peptide chain which prevents cross-linking = cell death

38
Q

Vancomycin resistance

A

The last D-Ala has been replaced by a D-lactate, preventing vancomycin binding

39
Q

Bacitracin

A

Interferes with dephosphorylation in cycling of lipid carrier that transfers peptidoglycan subunits to growing cell wall

40
Q

Tetracyclines

A

Bacteriostatic
Bind 30S subunit

Broad-spectrum

41
Q

Aminoglycosides

A

Generally bactericidal
Bind to 30S subunit

Oxygen-dependent (only will kill aerobic bacteria)

42
Q

Macrolides

A

Bacteriostatic
Bind 50S subunit

Alternative for those with penicillin allergies

43
Q

Quinolones

A

Bactericidal
Inhibits DNA replication, recombination, and repair

Affects DNA topoisomerase type II or IV

44
Q

Rifampin, rifabutin

A

Bactericidal

Binds to DNA-dependent RNA polymerase, inhibiting initiation of RNA synthesis

45
Q

Metronidazole

A

Bactericidal

Toxic compounds that damage DNA

46
Q

Antimetabolites

A

Target folate metabolism
Bacteriostatic

Sulfonamides and trimethoprim often used together for this

Microbio Exam 1 (8 decks)

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