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Microbiology > Lecture 6: Antibacterial Agents > Flashcards

Lecture 6: Antibacterial Agents Flashcards

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Biology 101 flashcards
1
Q

What is the germ theory of disease

A

The idea that microorganisms cause disease

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2
Q

Who discovered the first treatment for syphilis and what was it

A

Paul Ehrlich discovered Arsphenamine (Salvarsan)

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3
Q

Discovery of Arsphenamine (Salvarsan) also led to the foundation of the concept of ____

A

Chemotherapy

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4
Q

What was the first widely available antimicrobial

A

Prontosil

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5
Q

What antibiotic was discovered that started the “golden era” of antibiotics and by who

A

Alexander Fleming discovered penicillin

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6
Q

What is an antibiotic

A

Chemical substance that has the capacity to inhibit the growth of or kill bacterial cells

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7
Q

What does antimicrobial mean

A

Refers to agents that act against all types of microorganisms

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8
Q

What does it mean to be narrow spectrum

A

Effective against limited number of bacteria

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9
Q

What does it mean to be broad spectrum

A

Effective against a wider array of bacteria

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10
Q

What are the pros and cons of narrow spectrum agents

A

pros: treats only specific organisms, less resistance developed

Con: only effective if ID of bacterium is known/correct

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11
Q

What are some pros and cons of broad spectrum agents

A

Pro: less need to make ID
Con: increased development of resistance, disruption of normal microbiome

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12
Q

What does bactericidal mean

A

Kills bacteria

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13
Q

What does bacteriostatic mean

A

Inhibits growth of bacteria

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14
Q

Why don;t you want to give bacteriostatic agents to immunocompromised

A

Relying on immune system to make antibiotics and fight infection

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15
Q

What is selective toxicity

A

Target and kill bacterial cells and not host cells

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16
Q

What makes an antibiotic effective

A
  1. Selective toxicity
  2. Soluble in body fluids
  3. Toxicity is not easily altered
  4. Nonallergenic
  5. Stability
  6. Bacterial resistance is not easily acquired
  7. Reasonable cost
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17
Q

What are the 5 classes of antibiotics

A
  1. Inhibition of cell wall synthesis
  2. Disruption of membrane function
  3. Inhibition of protein synthesis
  4. Inhibition of nucleic acid synthesis
  5. Action as antimetabolites
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18
Q

How is peptidoglycan synthesized

A
  1. NAG and NAM subunits synthesized in cytoplasm
  2. NAG-NAM transported across cell membrane into periplasm
  3. AA side chains cross linked by transpeptidase
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19
Q

What are the 3 classes of cell wall synthesis inhibitors

A
  1. Beta-lactams
  2. Vancomycin
  3. Bacitracin
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20
Q

Are cell wall synthesis inhibitors bactericidal or bacteriostatic

A

Bactericidal

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21
Q

What is the most effective and most extensively used class of antibiotics

A

Cell wall synthesis inhibitors

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22
Q

What is the Beta-lactam ring

A

Active site of antibiotic

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23
Q

What are some notable examples of B-lactam antibiotics

A

Penicillin and cephalosporins

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24
Q

What bacteria does Beta-lactam target

A

Gram positive and negative

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25
Q

What is the mode of action of Beta-lactams

A

Binds and blocks activity of transpeptidase, preventing cross linking of peptidoglycan layers- resulting in loss of regulation of osmotic pressure- burst and die

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26
Q

Which generation of cephalosporins has highest activity against gram positives

A

First generation

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27
Q

What generation of cephalosporins have increasing coverage for gram negatives

A

Generations 2-5

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28
Q

What type of antibiotic is vancomycin

A

Glycopeptide antibiotic

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29
Q

What is vancomycin effective in tx? Narrow or broad spectrum

A

Narrow spectrum- mainly tx MRSA

30
Q

What is the mode of action for vancomycin

A

Binds to end the of pentapeptide chains (D-Ala-D-Ala) on NAM blocking transglycosylation and transpeptidation steps of peptidoglycan synthesis

31
Q

How is bacitracin administered and why

A

Topical use only due to toxicity

32
Q

What is bacitracin effective against, narrow or broad spectrum

A

Narrow spectrum: use for gram positive organisms, especially those causing skin infections

33
Q

What is the mode of action of bacitracin

A

Prevents dephosphorylation of bactoprenol (lipid carrier) preventing assembly and transport of NAG-NAM

34
Q

What class of antibiotic is polymixin

A

Disruption of cell membrane

35
Q

What is polymixin effective against, broad or narrow spectrum

A

Moderate spectrum against gram negative bacteria

36
Q

How is polymixin administered

A

Topical or ophthalmic due to toxicity

37
Q

What is the mode of action of polymixin

A

Acts as cationic detergent disrupting the membrane structure

38
Q

What ribosomes subunits are used in protein synthesis for bacteria

A

30S and 50S

39
Q

What do aminoglycosides target, narrow or broad spectrum

A

Broad spectrum- most common use is for tx of severe infections cause by aerobic gram negative bacilli

40
Q

What is the mechanism of action against aminoglycosides

A

Irreversibly bind to the 30S subunit and block the initiation complex, causing misreading of premature release of mRNA from the ribosome. Halts protein synthesis

41
Q

Are aminoglycosides bactericidal or bacteriostatic

A

Bactericidal

42
Q

What toxicities do aminoglycosides cause

A

Ototoxic and nephrotoxic in dogs and cats

43
Q

What are tetracyclines effective against, narrow or broad

A

Broad spectrum against many gram positives and negatives, many atypical pathogens

44
Q

What is the mode of action of tetracyclines

A

Binds to the 30S subunit to prevent attachment of the aminoacyl-tRNA to the RNA ribosome complex- prevents adding amino acids to peptide chain, halting protein synthesis

45
Q

Is tetracycline bactericidal or bacteriostatic

A

Bacteriostatic

46
Q

What antibiotic is toxic to human mitochondria causing aplastic anemia and bone marrow suppression? And which animals can it not be used in

A

Chloramphenicol- can’t be used in food animals

47
Q

What is the mode of action of amphenicols

A

Binds to the 50S subunit, inhibiting peptidyl transferase- prevents elongation of peptide chain, halting protein synthesis

48
Q

Are amphenicols bactericidal or bacteriostatic

A

Bacteriostatic

49
Q

What do macrolides tx, narrow or broad spectrum

A

Narrow spectrum against some gram negatives and mycoplasma

50
Q

What is the mode of action of macrolides

A

Binds to 50S subunit, blocking the formation of the initiation complex and translocation- prevents elongation, disrupt protein synthesis

51
Q

Are macrolides bactericidal or bacteriostatic

A

Bacteriostatic

52
Q

What do lincosamides tx,broad or narrow spectrum

A

Moderate spectrum- gram positive bacteria, anaerobes, some mycoplasms

53
Q

What is the mode of action for lincosamides

A

Binds the 50S subunit blocking the formation of initiation complex and translocation

54
Q

Is lincosamides bacteriostatic or bactericidal

A

Both

55
Q

What species is lincosamides toxic in

A

Rabbits, guinea pigs and hamsters

56
Q

What species are lincosamides contraindicated in

A

Horses, neonatal animals, oral administration in ruminants

57
Q

What does streptogramins tx, broad or narrow spectrum

A

Narrow spectrum for gram positive cocci resistant to other antibiotics

58
Q

What is the mode of action of streptogramins

A

Bind to different sites on the 50S ribosomal subunit, inhibition of protein synthesis at different steps

59
Q

What do quinolones/ fluoroquinoloes tx, broad or narrow spectrum

A

Broad spectrum used for enteric infections and intracellular pathogens

60
Q

What is the mode of action of quinilones/ fluoroquinolones

A

Bind to and inhibit DNA gyrase (topoisomerase II) and toposiomerase IV, preventing bacterial DNA from unwinding and duplicating

61
Q

Are quinolones/ fluoroquinolones bactericidal or bacteriostatic

A

Bactericidal

62
Q

What do rifamycins tx, broad or narrow spectrum

A

Moderate spectrum used for mycobacterial infections, some gram positive cocci, select gram negative, rhodoccous equin infections

63
Q

What is the mode of action for rifamycins

A

Inhibits DNA dependent RNA polymerase, prevents transcription of mRNA

64
Q

Are rifamycins bactericidal or bacteriostatic

A

Bactericidal

65
Q

What does metronidazole tx, broad or narrow specteum

A

Narrow spectrum mostly anaerobes and protozoans

66
Q

What is the mode of action of metronidazole

A

Covalently binds DNA, causing DNA. Breaks

67
Q

Is metronidazole bactericidal or bacteriostatic

A

Bactericidal

68
Q

What do sulfonamides and diaminopyrimidines tx, broad or narrow spectrum

A

Broad spectrum against a wide array of gram positive and negative

69
Q

What is the mode of action of sulfonamides and diaminopyrimidines

A

Interferes with folic acid synthesis needed for DNA synthesis

Sulfonamides inhibit diphydropteroate synthetase

Trimethoprum- inhibits enzyme dihydrofolate reductase

70
Q

What are some pros of antibiotic use

A

Reduce pain and suffering, weight gain, livestock live longer, prevent zoonotic diseases, prevent containment of potentially large scale epidemics

71
Q

What is the biggest con of antibiotic use

A

Multi drug resistant pathogens

Microbiology (31 decks)

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