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Bacteriology > Lecture 6 - Antibacterial Agents > Flashcards

Lecture 6 - Antibacterial Agents Flashcards

1
Q

What was the compound that Paul Ehrlich came up with?

A

Compound 606 aka Salvarsan

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2
Q

What was the first real antibiotic?

A

Penicillin (1928)

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3
Q

What is the definition of an antibiotic?

A

Chemical that is able to kill or inhibit the growth of bacterial cells

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4
Q

What is the definition of antimicrobial?

A

All agents that kill all types of microorganisms

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5
Q

What are the two very basic actions carried out by antibiotics?

A

Bacteriostatic + Bacteriocidal

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6
Q

What is bacteriostatic?

A

Inhibits the growth of bacteria

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7
Q

What is bacteriocidal?

A

Kills bacteria

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8
Q

What are the three categories in regards to spectrum of activity?

A

Narrow - Broad - Moderate

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9
Q

What is the major goal of antibiotic development (what should be one of the most important?

A

Selective toxicity

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10
Q

What is selective toxicity?

A

AB is more toxic to the bacterial cells than it is the host cells

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11
Q

What are some basic targets for antibiotics to ensure that they have selective toxicity?

A

Cell wall + Ribosomes + Bacterial enzymes

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12
Q

What does it mean to use antibiotics in a non-therapeutic manner?

A

Commonly seen in food animal medicine. This is the practice of using AB to prevent an infection from occurring before it is even present in the animal.

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13
Q

What is bad about the non-therapeutic use of AB’s?

A

This helps increase the rate in which bacterias become resistant to various antibiotics

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14
Q

What are the five classes of antibiotics?

A 
Inhibition of cell wall synthesis 
Disruption of cell membrane function 
Inhibition of protein synthesis 
Inhibition of nucleic acid synthesis 
Action as antimetabolite
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15
Q

What are the three AB’s that are inhibitors of cell wall synthesis?

A

Beta-Lactam
Glycopeptides
Bacitracin

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16
Q

What is the spectrum of activity of beta-lactam?

A

Varies

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17
Q

Is beta-lactam a -cidal or a -static?

A

Bactericidal

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18
Q

What is the mechanism of beta-lactam?

A

Binds/blocks transpeptidase
Prevents peptidoglycan cross-linking
Cell lysis

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19
Q

What is another name for transpeptidase?

A

Penicillin binding protein

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20
Q

What is the spectrum of activity for glycopeptides?

A

Narrow - Gram(+) only

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21
Q

Is glycopeptide -cidal or -static?

A

Bactericidal

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22
Q

What is the mechanism of glycopeptides?

A

Binds to the pentapeptide chains of NAM
Blocks transglycosylation + transpeptidation of peptidoglycan syn.
Cell lysis

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23
Q

What is the spectrum of activity for Bacitracin?

A

Broad

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24
Q

What is crucial to know clinically about Bacitracin?

A

Topical use only, too toxic for systemic use

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25
Q

Is Bacitracin -cidal or -static?

A

Bactericidal

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26
Q

What is the mechanism for Bacitracin?

A

Prevents dephosphorylation of bactoprenol
Prevents transport of NAG-NAM monomers
Cell lysis

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27
Q

What antibiotic works through disruption of the cell membrane?

A

Polymyxins

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28
Q

What is the spectrum for Polymyxins?

A

Moderate

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29
Q

What does polymyxin work on?

A

Gram-negative bacteria

30
Q

What is clinically important to know about polymyxin?

A

Poor selective toxicity therefore topical use only

31
Q

What is the mechanism for polymyxin?

A

Works as a cationic detergent
Increase water uptake into the cell
Cell lysis

32
Q

What ribosome type is found in bacteria?

33
Q

What are the subunits of the bacterial ribosome?

34
Q

What antibiotics target the 30s subunit of the bacterial ribosome?

A

Aminoglycosides + Tetracyclines

35
Q

What antibiotics target the 50s subunit of the bacterial ribosome?

A

Chloramphenicol
Macrolides
Lincosamides

36
Q

What is the spectrum of activity for aminoglycosides?

37
Q

What should the use of aminoglycosides be limited to?

A

Enteric infections and sometimes sepsis

38
Q

Are aminoglycosides -cidal or -static?

A

Bactericidal

39
Q

What is the mechanism for aminoglycosides?

A

Irreversible binding to 30s
Block initiation complex + misreading/premature release of mRNA
Stops protein synthesis h

40
Q

What is the spectrum of activity for tetracyclines?

41
Q

What is clinically important to know about tetracyclines?

A

Have non-antibacterial uses

Can be used as an anti-inflammatory

42
Q

Are tetracyclines -cidal or -static?

A

Bacteriostatic

43
Q

What is the mechanism of action for tetracylines?

A

Reversibly bind to ribosome
Prevent attachment of aminoacyl-tRNA to complex
Prevent AA addition to peptide chain
Halt protein syntheiss

44
Q

What is the spectrum of activity for chloramphenicol?

45
Q

What is clinically important to know about the use of chloramphenicol?

A

Can be toxic; causes aplastic anemia in humans

46
Q

Is chloramphenicol -cidal or -static?

A

Bacteriostatic

47
Q

What is the mechanism of chloramphenicol?

A

Reversibly binds to ribosome
Inhibits peptidyl transferase
Prevents elongation of peptide chain
Halts protein synthesis

48
Q

What is the spectrum of macrolides?

49
Q

Are macrolides -cidal or -static?

A

Bacteriostatic

50
Q

What is the mechanism for macrolides?

A

Reversibly binds to ribosome
Inhibits transpeptidation + translocation
Prevention of chain elongation + premature detachment of peptide
Halt protein synthesis

51
Q

What is the spectrum of activity for lincosamides?

52
Q

What microbes do lincosamides target?

A

Gram-postive
Anaerobes
Some mycoplasmas

53
Q

Are lincosamides -cidal or -static?

A

Bacteriostatic

54
Q

What is the mechanism of action for lincosamides?

A

Reversible binds to ribosome
Inhibit transpeptidation + translocation
Similar to macrolides
Halt protein synthesis

55
Q

What antibiotics target nucleic acid synthesis?

A

Quinolones + Fluoroquinolones
Rifamycins
Metronidazole

56
Q

Are quinolones -cidal or -static?

A

Bactericidal

57
Q

What is the spectrum of quinolones?

A

Varies - normally broad

58
Q

What is the mechanism for quinolones?

A

Bind to DNA gyrase + topoisomerase IV
Inhibit bacterial replication via interference with DNA supercoiling
Stop DNA/RNA synthesis

59
Q

What is the spectrum of activity for rifamycin?

60
Q

Are rifamycins -cidal or -static?

A

Bactericidal

61
Q

What is the mechanism of action for rifamycins?

A

Inhibits DNA-dependent RNA polymerase

Stops transcription of mRNA

62
Q

What is the spectrum of activity for metronidazole?

63
Q

What microbes does metronidazole target?

A

Anaerobes + Protozoans

64
Q

Is metronidazole -cidal or -static?

A

Bactericidal

65
Q

What is the mechanism for metronidazole?

A

Reduction into active form
Covalently binds to DNA = breakage
Inhibits NA synthesis

66
Q

What antibiotics are antimetabolites?

A

Sulfonamides + Diaminopyrimidines

67
Q

Are the antimetabolite AB’s -cidal or -static?

A

If used alone they are bacteriostatic

If used together (common) bacteriocidal

68
Q

What is the mechanism of the antimetabolites?

A

Interfere with folic acid synthesis

69
Q

What is the specific mechanism of sulfonamides?

A

Analog of PABA - compete for the enzyme dihydropteroate synthetase

70
Q

What is the specific mechanism for diaminopyrimidines?

A

Analogs of pteridine portion of dihydrofolic acid - inhibit dihyro reductase

71
Q

Who was the first person to begin to find a compound that would kill infectious microbes?

A

Paul Ehrlich

Bacteriology (28 decks)

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