Brainscape's Knowledge GenomeTM


Top Flashcards (Certified)
All Flashcards

Chemotherapy BMSC2210 > Antibacterial chemotherapy > Flashcards

Antibacterial chemotherapy Flashcards

1
Q

What are the common characteristics of antibacterials that target protein synthesis?

A

Natural products

Most target the ribosome directly and are bacteriostatic

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What is the basis for selective toxicity in antibacterials that target protein synthesis?

A

Drugs can discriminate between the subtle structural differences between the bacterial and mammalian ribosomes - inhibit mitochondrial protein synthesis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What does bacteriostatic mean?

A

Agent prevents bacterial growth

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What does bactericidal mean?

A

Agent kills the bacteria

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What is the target for Mupirocin?

A

Isoleucyl tRNA synthetase (does not go near the ribosome)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Mupirocin - bactericidal or bacteriostatic?

A

Bacteriostatic

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What is the mode of action for Mupirocin?

A

Acts as substrate analogue, binds isoleucyl tRNA synthetase and competitively inhibits the binding of isoleucine so protein synthesis can’t occur

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Does Mupirocin treat Gram +ve or Gram -ve bacteria and why?

A

Gram +ve, because outer membrane of Gram -ve bacteria restricts access of Mupirocin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What is the clinical use of Mupirocin?

A

Topical ointment for staph and strep skin infections and eliminates nasal carriage MRSA

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Why is Mupirocin not treated systemically?

A

Because it is rapidly de-esterified in the kidney and liver

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What are the adverse effects of Mupirocin?

A

Generally well tolerated

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What is the target for the Oxazolidinones?

A

Binding site on 50S (larger) ribosomal subunit

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Oxazolidinones - bactericidal or bacteriostatic?

A

Bacteriostatic

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Do oxazolidinones treat Gram +ve or Gram -ve bacteria and why?

A

Gram +ve, because the drug is removed by efflux in Gram -ve

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What is the mode of action of the oxazolidinones?

A

Interferes with binding/correct positioning of initiator tRNA in ribosomal P site

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What is the clinical use of the oxazolidinones?

A

IV and oral agents to treat community and hospital acquired pneumonia and skin/soft tissue infections

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What are the adverse effects of oxazolidinones?

A

Skin reactions
Gastrointestinal disturbances
Mild and transient abnormalities in liver function
Reversible thrombocytopenia (decreased blood platelet level)
Anaemia

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What is the target for the Tetracyclines?

A

The A site within the 30S ribosome

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What is the mode of action of the tetracylines?

A

Bind the A site in the 30S subunit preventing association of aminoacyl-tRNA with the ribosome, preventing amino acid delivery (bacteriostatic)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

Do tetracyclines treat Gram +ve or Gram -ve bacteria?

A

Both - they are broad spectrum

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

What is the clinical use of the Tetracyclines?

A

Mostly oral (tigecycline is IV too) used to treat skin, soft tissue and intra-abdominal infections

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

What ate the adverse effects of tetracyclines?

A

Gastrointestinal disturbances for oral products
Photosensitivity – UV sensitive – sunburn
CNS effects (particularly minocycline) - reversible
Deposition in developing bones & teeth (contraindicated in pregnancy and young children as can lead to discolouration and hyperplasia)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

What is the target for aminoglycosides?

A

30S subunit via 16S rRNA (some bind both 30S and 50S subunits)

24
Q

Aminoglycosides - bactericidal or bacteriostatic?

A

Bactericidal (kill bacteria) unlike others

25
What is the mode of action of the aminoglycosides?
Bind 30S subunit which reduces translational fidelity of the ribosome (increase error rate) Abnormal proteins are produced containing external hydrophobic patches The proteins escape the aqueous environment by folding into the membrane The membrane integrity is compromised leading to leakage of cell contents and cell death
26
What is the clinical use of the aminoglycosides?
Mostly IM/IV Used alone for: Severe sepsis by Enterobacteriaceae and Ps. Aeruginosa Plague and tularaemia Enterococcal endocarditis Used in combination for: Gram +ve and anaerobic infections and tuberculosis
27
Are aminoglycosides used to treat Gram +ve or Gram -ve?
Both - broad spectrum
28
What are the adverse effects of aminoglycosides?
Mechanism based toxicity: Ototoxicity Nephrotoxicity Neuromuscular blockade
29
What is the target for Chloramphenicol?
50S subunit at site overlapping the amino-acyl moiety of A site tRNA (PTC)
30
What is the mode of action of Chloramphenicol?
Blocks amino-acyl tRNA binding - inhibiting protein synthesis
31
What is the clinical use of Chloramphenicol?
Oral or topical Truly broad spectrum toxicity restricts clinical use but still used to treat typhoid and paratyphoid fever caused by Salmonella spp.
32
What are the adverse effects of Chloramphenicol?
``` Myelosuppression potentially leading to aplastic anaemia Gray syndrome (immature excretion mechanisms) ```
33
What is the target for the Macrolides?
The 23S rRNA at the peptide exit of the 50S subunit
34
What is the mode of action of the Macrolides?
Bind the 23S rRNA at the peptide exit of the 50S subunit blocking the exit of growing peptides causing premature dissociation of the peptidyl-tRNA from the P site
35
What is the clinical use of Macrolides?
``` Oral and IV Chlamydial infections Mycoplasmal pneumonia Syphilis Corynebacterium diphtheria Legionnaire's disease ```
36
What are the adverse side effects of Macrolides?
Generally well tolerated Some gastrointestinal disturbances Jaundice Ototoxicity
37
What is the target for Fusidic acid?
Ribosome accessory factor
38
What is the mode of action of fusidic acid?
Binds accessory factor and interferes with release of elongation factor G from the ribosome
39
Does fusidic acid treat Gram +ve or Gram -ve
Only Gram +ve
40
What are the clinical uses of Fusidic acid?
Topical, oral and IV therapy of staph infections
41
What are the adverse effects of Fusidic acid?
Rashes Jaundice (Relatively rare)
42
What are the two mechanisms by which antibacterials can target membranes?
Cytoplasmic membrane integrity | Cell wall synthesis
43
Which two antibacterial classes target cell wall biosynthesis?
B-lactams and Glycopeptides
44
What is the target for B-lactams?
Transpeptidation (cross linking between glycan strands) - structural analogues not competitive inhibitors
45
What is the mode of action of the B-lactams?
Don't act as a competitive inhibitor but fool the enzyme into thinking that the correct substrate is bound, prevents cross linking of peptide Less able to resist osmotic pressure - lysis and cell death
46
What are the clinical applications of B lactams?
Very versatile - wide and extensive use for virtually all bacterial infections (except those that lack a cell wall)
47
What are the adverse effects of B lactams?
One of the safest antibacterials Hypersensitivity can occur (variety of skin eruptions) Anaphylactic shock risk after injection
48
What is an issue with B lactam?
Showed resistance relatively early on
49
What enzyme mediates B lactam resistance?
B lactamases
50
What is the role of Clavulanic acid?
Lactamase inhibitor administered with B lactam to prevent resistance
51
What are the four subclasses of B lactams?
Penicillins - "cillin" Cephalosporins - "cef" Carbapenems - "penem Monobactams - "Aztreonam"
52
How are cephalosporins administered?
IV or IM
53
What are the therapeutic applications of cephalosporins?
``` Gram +ve and -ve Relatively broad (especially fourth generations) ```
54
How are the Carbapenems administered?
Parentally Imipenem - IV Meropenem - IV Ertapenem - IV/IM
55
What are the therapeutic applications of carbapenems?
Extremely broad but ordinarily reserved for more serious infections Used when bacteria is resistant to penicillin and cephalosporin
56
Name the main glycopeptide antibiotic
Vancomycin
57
What is the mode of action of vancomycin?
Primarily affects transglycosylation (but transpeptidation also impacted)

Chemotherapy BMSC2210 (8 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions