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Clinical Bacteriology (Prelim) > (Lecture) Actions of Antimicrobials > Flashcards

(Lecture) Actions of Antimicrobials Flashcards

1
Q

Chemical substances that are produced by microorganisms that has the capacity to inhibit or kill other microorganisms.

A

Antibiotics

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2
Q

The lowest concentration of a drug that can inhibit bacterial growth.

A

Minimum-Inhibitory Concentration (MIC)

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3
Q

The lowest concentration of a drug that can still kill bacteria.

A

Minimum-Bactericidal Concentration (MBC)

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4
Q

Ratio of a toxic dose to the therapeutic dose; the higher the index, the more effective the chemotherapeutic agent.

A

Therapeutic Index

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5
Q

Characteristics of Antimicrobial Agents

A

● The agent must be in active form.
● The agent must be able to achieve concentration at the site of infection that is higher than the pathogen’s MIC to be effective.
● Must have selective toxicity.

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6
Q

_____ inhibit cell wall synthesis by binding to the end of the peptidoglycan, preventing transpeptidation.

A

Glycopeptides

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7
Q

Glycopeptides inhibit cell wall synthesis by binding to the end of the peptidoglycan, preventing _____

A

Transpeptidation

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8
Q

Glycopeptides inhibit cell wall synthesis by binding to the end of the _____, preventing transpeptidation

A

Peptidoglycan

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9
Q

What type of Antimicrobial Agents is this based on the description?

● Selective antibiotics with high therapeutic index
● Interferes with the biosynthesis of peptidoglycan
● The beta-lactam antibiotics form covalent complexes with enzymes that generate mature peptidoglycan molecule (transpeptidase enzymes that mediate peptidoglycan cross-linking)
● The active component of the beta-lactam family of drugs is the beta-lactam structure.
● Glycopeptides inhibit cell wall synthesis by binding to the end of the peptidoglycan, preventing transpeptidation.

A

Cell Wall Inhibitors

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10
Q

_____ prevents the formation of dihydropteroate through competitive inhibition of para-aminobenzoic acid with the enzyme dihydropteroate synthase

A

Sulfamethoxazole/SMZ

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11
Q

Sulfamethoxazole/SMZ (a sulfonamide) prevents the formation of dihydropteroate through competitive inhibition of para-aminobenzoic acid with the enzyme _____

A

Dihydropteroate synthase

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12
Q

Sulfamethoxazole/SMZ (a sulfonamide) prevents the formation of _____ through competitive inhibition of para-aminobenzoic acid with the enzyme dihydropteroate synthase

A

Dihydropteroate

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13
Q

_____ blocks the formation of the tetrahydrofolate by inhibiting dihydrofolate reductase.

A

Trimethoprim

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14
Q

Trimethoprim blocks the formation of the _____ by inhibiting dihydrofolate reductase.

A

Tetrahydrofolate

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15
Q

Trimethoprim blocks the formation of the tetrahydrofolate by inhibiting _____

A

Dihydrofolate reductase

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16
Q

What type of Antimicrobial Agents is this based on the description?

● The folic acid pathway provides essential precursor molecules needed for DNA biosynthesis
● Sulfamethoxazole/SMZ (a sulfonamide) prevents the formation of dihydropteroate through competitive inhibition of para-aminobenzoic acid with the enzyme dihydropteroate synthase
● Trimethoprim blocks the formation of the tetrahydrofolate by inhibiting dihydrofolate reductase.

A

Inhibitors of Folate Synthesis

17
Q

These are necessary for DNA replication

A

Topoisomerases I, II, III, and IV

18
Q

_____ affect DNA replication by targeting topoisomerases II (DNA gyrase) in Gram-negative bacteria and Topoisomerase IV in Gram-positive bacteria

A

Quinolones

19
Q

Quinolones affect DNA replication by targeting _____ in Gram-negative bacteria and _____ in Gram-positive bacteria

A

Topoisomerases II
Topoisomerases IV

20
Q

What type of Antimicrobial Agents is this based on the description?

● Topoisomerases I, II, III, and IV are necessary for DNA replication
● Quinolones affect DNA replication by targeting topoisomerases II (DNA gyrase) in Gram-negative bacteria and Topoisomerase IV in Gram-positive bacteria

A

Agents that Interfere with DNA Replication

21
Q

_____ of DNA into RNA is mediated by RNA polymerase

A

Transcription

22
Q

Transcription of DNA into RNA is mediated by _____

A

RNA polymerase

23
Q

_____ targets the RNA polymerase subunit, blocking RNA chain elongation.

A

Rifampin

24
Q

What type of Antimicrobial Agents is this based on the description?

● Transcription of DNA into RNA is mediated by RNA polymerase
● Rifampin targets the RNA polymerase subunit, blocking RNA chain elongation.

A

Agents that Interfere with DNA Transcription

25
Q

List down some of the antibiotics that target the 30S ribosomal subunit.

A

Aminoglycosides
Spectinomycin
Tetracyclines
Glycylcyclines

26
Q

List down some of the antibiotics that target the 50S ribosomal subunit.

A

Macrolides
Lincosamides
Chloramphenicol
Oxazolidinones
Streptogramins

27
Q

Only _____ are bactericidal; the rest are bacteriostatic

A

Aminoglycosides

28
Q

Antibiotics that have side effects

A

Aminoglycosides, Chloramphenicol, and Tetracycline

29
Q

What type of Antimicrobial Agents is this based on the description?

● Some antibiotics target the 30S ribosomal subunit (aminoglycosides, spectinomycin, tetracyclines, glycylcyclines)
● Others target the 50S ribosomal subunit (macrolides, lincosamides, chloramphenicol, oxazolidinones, streptogramins)
● Only aminoglycosides are bactericidal; the rest are bacteriostatic
● Aminoglycosides, chloramphenicol, and tetracycline have side effects.

A

Agents that Inhibit Protein Synthesis

30
Q

_____ serve as outer membrane channels that permit the influx of nutrients and efflux of waste products.

A

Porins

31
Q

_____ are found in bacteria and function as transporter proteins for the extrusion of toxic substances and antibiotics from the interior of the cell to the external environment.

A

Efflux Pumps

32
Q

_____ are enzymes that hydrolyzes beta-lactams, preventing the antibiotic’s ability to bind transpeptidase enzymes

A

Beta-lactamases

33
Q

Beta-lactamases are enzymes that hydrolyzes beta-lactams, preventing the antibiotic’s ability to bind _____

A

Transpeptidase enzymes

34
Q

The inhibitors that bind beta-lactamases and reduces their detrimental effects on the beta-lactam antibiotics.

A

Clavulanic acid
Sulbactam
Tazobactam

35
Q

_____ compete with dihydropteroate synthase enzymes to block the formation of nucleotide precursors.

A

Sulfonamides

Clinical Bacteriology (Prelim) (17 decks)

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