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BIO1337 - Microbiology > Antibiotics > Flashcards

Antibiotics Flashcards

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
What do aminoglycosides inhibit?
Ribosome function
26
Are aminoglycosides commonly used?
No
27
What are aminoglycosides considered to be?
A reserve antibiotic fo when other antibiotics fail
28
What are macrolides?
Contains lactone rings bonded to sugars
29
What is does the macrolide target?
50s subunit of ribosome
30
What is an example of macrolide?
Erythromycin
31
What are tetracyclines?
Contains four rings
32
What is the use of tetracyclines?
- Widespread medical use in human/animals - Inhibition of protein synthesis - Inhibits function of 30S ribosomal subunits
33
What is the name for naturally occurring penicillin?
Benzylpenicillin
34
Is benzylpenicillin antibiotic against Gram-positive or Gram-negative bacteria?
Gram-poistive
35
How is natural penicillin modified?
By the R-group
36
What are the different semi-synthetic penicillin's?
- Methicillin - Oxacillin - Ampicillin
37
What do quinolones bind to?
the A subunit of DNA gyrase (A2B2)
38
What does modification of naturally occurring bacterial allow?
Targeting of a range of bacteria
39
What is penicillin involved in targeting?
Peptidoglycan synthesis
40
What type of antibiotic agent is aminoglycosides?
Bacteriostatic
41
What type of antibiotic agent is Macrolides?
Bacteriostatic
42
What type of antibiotic agent is tetracyclines?
Bacteriostatic
43
Is antibiotics more used in human or agriculture?
Agriculture
44
What type of antibiotic is must frequently used?
Penicillin
45
What group of antibiotic is the most important?
Beta-Lactam antibiotics
46
What antibiotics does the group of Beta-Lactam antibodies include?
- Penicillins - Cephalosporins - Cephamycins
47
How discovered penicillin?
Alexander Fleming
48
What is penicillin primary effective against?
Gram-positive bacteria
49
What type of penicillin is effective against Gram-negative bacteria
Synthetic forms of Penicillins
50
What do pencilling target?
Cell wall synthesis
51
How many antibiotics discovered are clinically useful?
Less than 1%
52
What are three different types of inhibitions that antibiotics do again bacteria?
- Transcription inhibition - Translation inhibition - Cell wall biosynthesis inhibitors
53
Give examples of transcription inhibitors antibiotics:
- Actinomycin | - Rifampin
54
How do transcription inhibitors antibiotics work?
Interfere with gene expression
55
How does actinomycin work as a transcription inhibitor?
- Inhibits transcription - Binding tightly to double stranded DNA at G-C base pairs - Binding prevents DNA strand from unwinding - Blocks RNA polymerase
56
Why does actinomycin have a limited application in medicine?
Lacks specificity and produces toxicity
57
How does rifampin work as a transcription inhibitor?
-Binds to RNA polymerase
58
How does bacteria become resistant to rifampin?
Mutation in gene for B subunit of RNA polymerase
59
What is rifampin effective against?
Mycobacteria and other Gram-positive bacteria
60
How do translation inhibitors antibiotics work?
Disrupting ribosome
61
What are examples of translation inhibitor antibiotics?
- Aminoglycoside streptomycin - Tetracycline - Chloramphenicol - Puromycin - Macrolide
62
How does amino glycoside streptomycin work as a translation inhibitor?
- Binds irreversibly to 30s ribosomal subunits - Inhibits translation intiation - Also misread information of mRNA - Non functional protein
63
What are glycoside streptomycin effective against?
aerobic gram-negative rods and some Gram-positive organisms
64
How does amino tetracycline work as a translation inhibitor?
- Binds reversibly to 30S ribosomal subunit | - Prevents incoming aminoacyl-tRNAs from binding to A site of ribosome
65
What was the first broad-spectrum antibiotics?
Tetracycline
66
What does tetracycline inhibit?
Most Gram-negative and Gram-positive
67
What is the must important antibiotics in medicine?
Tetracycline
68
How does Chloramphenicol work as a translation inhibitor?
-Binds reversibly to 50S ribosome subunit and inhibit formation of peptide bonds between amino acids
69
What does Chloramphenicol work on?
Gram-negative/positive
70
What is a problem with Chloramphenicol?
Toxic - some patients taking antibiotics develop potential fatal conditions of aplastic anemia
71
How does puromycin work as a translation inhibitor?
- 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
Does puromycin inhibit protein synthesis in all organism?
Yes
73
How does macrolide work as a translation inhibitor?
- 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
When do you use macrolide?
When some is allergic to penicillin
75
What are antibiotic examples of cell wall biosynthesis inhibitors?
-B-lactam group
76
Is penicillin G in B-lactam group?
Yes
77
What structural components do B-lactam group have?
B lactam ring
78
Is penicillin G a natural or synthetic antibiotic?
Natural antibiotic
79
How do semi-synthetic penicillins differ?
N-acyl groups
80
How does penicillin G work?
- 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
What is a famous antibiotics?
Vancomycin
82
How does vancomycin work?
Inhibits cell wall biosynthesis
83
Does vancomycin have a poor or good bioavailability?
Poor bioavailability
84
What antibiotic do you use to treat C. difficile?
Vancomycin
85
What is the role of transpeptidase enzyme?
Catalyse a link between glycan chains
86
How do you measure antibacterial activity?
- 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
What has almost all pathogenic microbes acquired resistance to?
Chemotherapeutic agents
88
How can resistance be minimised?
Using antibiotics correctly and only when needed
89
What are the 5 antibiotic resistance categories?
- 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
What do most drug-resistant bacteria isolate from patients contain?
Drug-resistance genes located on R plasmids
91
What selects for the spread of R plasmids?
Use of antibiotics in medicine, veterinary and agriculture
92
What do R plasmids contain?
- Resistance transfer facto - enables conjugation | - Genes conferring resistance

BIO1337 - Microbiology (18 decks)

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