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BIO1337 - Microbiology > Antibiotics > Flashcards

Antibiotics Flashcards

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1
Q

What are the different types of antimicrobial agents?

A
  • Bacteriostatic
  • Bactericidal
  • Bacteriolytic
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2
Q

What is a bacteriostatic agent?

A

stops growth of bacteria

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3
Q

What is a bactericidal agent?

A

kills the cells of bacteria

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4
Q

What is a bacteriolytic agent?

A

causes cell to be lysed

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5
Q

What does a bacteriostatic graph look like relating to the total cell count and viable cell count?

A

Directly proportional increase until introduction of agent where the total cell count and viable cell count becomes stationary

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6
Q

What does a bactericidal graph look like relating to the total cell count and viable cell count?

A

Directly proportional increase until introduction of agent.
Total count becomes stationary
Viable cell count decreases

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7
Q

What does a bacteriolytic graph look like relating to the total cell count and viable cell count?

A

Directly proportional increase until introduction of agent.

Both lines decreases

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8
Q

What is a total cell count?

A

Cells of all both dead and alive

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9
Q

What is a viable cell count?

A

Cells of only living

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10
Q

What are the majority of antibiotics structures based on?

A

Against bacteria structure or cellular processes

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11
Q

Why is there a resistance to antibiotics?

A

Massive selective pressure from bacteria to evolve

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12
Q

What do quinolones target?

A

DNA gyrase

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13
Q

What is DNA gyrase?

A

Protein involved in unwinding DNA

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14
Q

What is the use of antibiotics having quinolones?

A

Protein will not be able to replicate, therefor cannot reproduce

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15
Q

What do you call an antibiotic if it cannot synthesis a new wall?

A

Bacteriolytic

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16
Q

What is another name for antibiotics?

A

Antimicrobials

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17
Q

Are all antibiotics synthesis in the lab?

A

No, they can be naturally occurring

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18
Q

What do you call a modification of natural antibiotics?

A

Semi-synthetic antibiotics

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19
Q

What do the brackets at the end of bacterial species represent?

A

Endospore forming bacteria

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20
Q

What does a bacterial species with a (A) at the end mean?

A

Actinomyces

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21
Q

What does a bacterial species with a (F) at the end mean?

A

Fungi

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22
Q

Give an example fo naturally occurring antibiotics?

A

Aminoglycosides
Macrolides
Tetracyclines

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23
Q

What are aminoglycosides?

A

Antibiotics that contain amino sugars bonded by glycosidic linkage

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24
Q

What are examples of aminoglycosides antibiotics?

A

Kanamycin
Neomycin
Amikacin

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25
Q

What do aminoglycosides inhibit?

A

Ribosome function

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26
Q

Are aminoglycosides commonly used?

A

No

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27
Q

What are aminoglycosides considered to be?

A

A reserve antibiotic fo when other antibiotics fail

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28
Q

What are macrolides?

A

Contains lactone rings bonded to sugars

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29
Q

What is does the macrolide target?

A

50s subunit of ribosome

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30
Q

What is an example of macrolide?

A

Erythromycin

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31
Q

What are tetracyclines?

A

Contains four rings

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32
Q

What is the use of tetracyclines?

A
  • Widespread medical use in human/animals
  • Inhibition of protein synthesis
  • Inhibits function of 30S ribosomal subunits
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33
Q

What is the name for naturally occurring penicillin?

A

Benzylpenicillin

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34
Q

Is benzylpenicillin antibiotic against Gram-positive or Gram-negative bacteria?

A

Gram-poistive

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35
Q

How is natural penicillin modified?

A

By the R-group

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36
Q

What are the different semi-synthetic penicillin’s?

A
  • Methicillin
  • Oxacillin
  • Ampicillin
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37
Q

What do quinolones bind to?

A

the A subunit of DNA gyrase (A2B2)

38
Q

What does modification of naturally occurring bacterial allow?

A

Targeting of a range of bacteria

39
Q

What is penicillin involved in targeting?

A

Peptidoglycan synthesis

40
Q

What type of antibiotic agent is aminoglycosides?

A

Bacteriostatic

41
Q

What type of antibiotic agent is Macrolides?

A

Bacteriostatic

42
Q

What type of antibiotic agent is tetracyclines?

A

Bacteriostatic

43
Q

Is antibiotics more used in human or agriculture?

A

Agriculture

44
Q

What type of antibiotic is must frequently used?

A

Penicillin

45
Q

What group of antibiotic is the most important?

A

Beta-Lactam antibiotics

46
Q

What antibiotics does the group of Beta-Lactam antibodies include?

A
  • Penicillins
  • Cephalosporins
  • Cephamycins
47
Q

How discovered penicillin?

A

Alexander Fleming

48
Q

What is penicillin primary effective against?

A

Gram-positive bacteria

49
Q

What type of penicillin is effective against Gram-negative bacteria

A

Synthetic forms of Penicillins

50
Q

What do pencilling target?

A

Cell wall synthesis

51
Q

How many antibiotics discovered are clinically useful?

A

Less than 1%

52
Q

What are three different types of inhibitions that antibiotics do again bacteria?

A
  • Transcription inhibition
  • Translation inhibition
  • Cell wall biosynthesis inhibitors
53
Q

Give examples of transcription inhibitors antibiotics:

A
  • Actinomycin

- Rifampin

54
Q

How do transcription inhibitors antibiotics work?

A

Interfere with gene expression

55
Q

How does actinomycin work as a transcription inhibitor?

A
  • Inhibits transcription
  • Binding tightly to double stranded DNA at G-C base pairs
  • Binding prevents DNA strand from unwinding
  • Blocks RNA polymerase
56
Q

Why does actinomycin have a limited application in medicine?

A

Lacks specificity and produces toxicity

57
Q

How does rifampin work as a transcription inhibitor?

A

-Binds to RNA polymerase

58
Q

How does bacteria become resistant to rifampin?

A

Mutation in gene for B subunit of RNA polymerase

59
Q

What is rifampin effective against?

A

Mycobacteria and other Gram-positive bacteria

60
Q

How do translation inhibitors antibiotics work?

A

Disrupting ribosome

61
Q

What are examples of translation inhibitor antibiotics?

A
  • Aminoglycoside streptomycin
  • Tetracycline
  • Chloramphenicol
  • Puromycin
  • Macrolide
62
Q

How does amino glycoside streptomycin work as a translation inhibitor?

A
  • Binds irreversibly to 30s ribosomal subunits
  • Inhibits translation intiation
  • Also misread information of mRNA
  • Non functional protein
63
Q

What are glycoside streptomycin effective against?

A

aerobic gram-negative rods and some Gram-positive organisms

64
Q

How does amino tetracycline work as a translation inhibitor?

A
  • Binds reversibly to 30S ribosomal subunit

- Prevents incoming aminoacyl-tRNAs from binding to A site of ribosome

65
Q

What was the first broad-spectrum antibiotics?

A

Tetracycline

66
Q

What does tetracycline inhibit?

A

Most Gram-negative and Gram-positive

67
Q

What is the must important antibiotics in medicine?

A

Tetracycline

68
Q

How does Chloramphenicol work as a translation inhibitor?

A

-Binds reversibly to 50S ribosome subunit and inhibit formation of peptide bonds between amino acids

69
Q

What does Chloramphenicol work on?

A

Gram-negative/positive

70
Q

What is a problem with Chloramphenicol?

A

Toxic - some patients taking antibiotics develop potential fatal conditions of aplastic anemia

71
Q

How does puromycin work as a translation inhibitor?

A
  • Binds to A site of 50S ribosomal subunit
  • Mimics structure of aminoacyl-tRNA
  • Forms peptide bond in P site
  • Complex leaves ribosome prematurely terminating translation
72
Q

Does puromycin inhibit protein synthesis in all organism?

A

Yes

73
Q

How does macrolide work as a translation inhibitor?

A
  • Binds to 50s ribosomal subunit and inhibits protein synthesis
  • Occurs during transfer of peptidyl-tRNA from A site to P site
  • Antibiotics blocks polypeptide transfer
  • Halts translocation
74
Q

When do you use macrolide?

A

When some is allergic to penicillin

75
Q

What are antibiotic examples of cell wall biosynthesis inhibitors?

A

-B-lactam group

76
Q

Is penicillin G in B-lactam group?

A

Yes

77
Q

What structural components do B-lactam group have?

A

B lactam ring

78
Q

Is penicillin G a natural or synthetic antibiotic?

A

Natural antibiotic

79
Q

How do semi-synthetic penicillins differ?

A

N-acyl groups

80
Q

How does penicillin G work?

A
  • Disrupts formation of new cell wall during bacterial growth
  • Prevents transpetidase enzyme from catalysing the glycol chains via binding to enzyme
  • Glycan chain will lack cross link and be weak
  • Cells lyse under extreme somatic pressure
81
Q

What is a famous antibiotics?

A

Vancomycin

82
Q

How does vancomycin work?

A

Inhibits cell wall biosynthesis

83
Q

Does vancomycin have a poor or good bioavailability?

A

Poor bioavailability

84
Q

What antibiotic do you use to treat C. difficile?

A

Vancomycin

85
Q

What is the role of transpeptidase enzyme?

A

Catalyse a link between glycan chains

86
Q

How do you measure antibacterial activity?

A
  • Inoculate plate with a liquid culture of a test organism
  • Discs containing antimicrobial agents are places on surface
  • Incubate for 24-48 hours
  • If organisms show susceptibility to some against = indicate inhibition of bacterial growth around discs (zone of inhibition)
87
Q

What has almost all pathogenic microbes acquired resistance to?

A

Chemotherapeutic agents

88
Q

How can resistance be minimised?

A

Using antibiotics correctly and only when needed

89
Q

What are the 5 antibiotic resistance categories?

A
  • Organisms lacks structure the antibiotics inhibits
  • Organisms is impermeable to antibiotic
  • Organisms can inactivate the antibiotic
  • Organisms may modify the target of the antibiotic
  • Organisms may be able to pump out the antibiotic
90
Q

What do most drug-resistant bacteria isolate from patients contain?

A

Drug-resistance genes located on R plasmids

91
Q

What selects for the spread of R plasmids?

A

Use of antibiotics in medicine, veterinary and agriculture

92
Q

What do R plasmids contain?

A
  • Resistance transfer facto - enables conjugation

- Genes conferring resistance

BIO1337 - Microbiology (18 decks)

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