Pharmacology of Antibiotics Flashcards

1
Q

Antibacterial Chemotherapy Targets

A

Bacterial cell walls
Bacterial ribosomes
Bacterial folate metabolism
Bacterial DNA gyrases

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2
Q

Antibacterials vs antibiotics

A

Antibiotics are antibacterials that are produced by an organism to attack other organisms (e.g. penicillin) while antibacterials are more of an umbrella

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3
Q

Beta lactam ring

A

Feature of penicillins

can be a weakness and be targeted by bacteria since it is unstable

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4
Q

Mode of action of penicillins

A

Target bacterial cell wall synthesis by binding irreversibly to the transpeptidase which cross links peptidoglycans in the bacterial cell wall

Thus it is only effective against dividing organisms as division requires cell walls synthesis, leading to lysis

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5
Q

Is penicillin bactericidal (also what is bactericidal)

A

Penicillins are bactericidal

They cause lysis of the bacteria

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6
Q

Beta-lactamase

A

Enzymes produced by bacteria that cause cleavage in the beta lactam rings

Note that some penicillins are resistant to beta lactamases

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7
Q

Clavulanic acid

A

An acid that is included with some agents to inhibit the beta lactamases

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8
Q

Immunogenic

A

Relating to or denoting substances able to produce an immune response.

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9
Q

Penicillin allergies

A

Penicillin is immunogenic so about 10% of patients treated with it can develop allergies

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10
Q

Cephalosporins

A

Beta-lactam antibiotics that act in a very similar way to penicillin

Do not prescribe them to patients who are allergic to penicillin as a small percentage of them would also be sensitive to cephalosporins

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11
Q

Glycopeptides

A

Antibacterials used against very resistant bacteria like MRSA

Inhibit bacterial cell wall synthesis by inhibiting the growth of the peptidoglycan chain

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12
Q

Are glycopeptides bactericidal

A

Yes (mostly)

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13
Q

Example of a glycopeptide

A

Vancomycin

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14
Q

Tetracyclines

A

Antibacterials that inhibit protein synthesis by binding to the 30S subunit of bacterial ribosomes and preventing tRNA from binding at the A(cceptor) site

Actively accumulate in bacterial cells

Have decreased use due to resistance

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15
Q

Bacteriostatic

A

Prevents the growth of bacteria

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16
Q

Are tetracyclines bacteriostatic

A

Yes

17
Q

Macrolides

A

Antibacterials that prevent the translocation of the 50S subunit of the bacterial ribosome along the mRNA (prevents protein synthesis)

18
Q

Example of macrolide

A

Erythromycin

19
Q

Are macrolides bacteriostatic or bactericidal

A

They are bacteriostatic

20
Q

Which antibacterials are used as a common alternative to penicillins in resistant patients

A

Macrolides

21
Q

What is the difficulty of using macrolides

A

They are cytochrome inhibitors associated with a range of drug interactions (e.g. decreasing drug clearance and causing toxicity)

22
Q

Aminoglycocide

A

Antibacterials that bind irreversibly to the 30S subunit of bacterial ribosomes leading to mRNA being misread; interferes with protein synthesis

23
Q

Example of aminoglycoside

A

Gentamicin

24
Q

Are aminoglycosides bactericidal or bactereostatic

A

Bactericidal - used to manage gram-negative bacteria

25
Q

What antibacterial does aminoglycoside work with

A

They synergise with penicillins (breaks down cell wall, increasing aminoglycoside uptake)

26
Q

Otoxicity

A

When a person develops hearing or balance problems due to a medicine

27
Q

Difficulties of using aminoglycosides/gentamicin

A

Ototoxicity/Nephrotoxicity

When used, dose it in a way that there is a sub-therapeutic blood concentration at some points

28
Q

Quinolones

A

Inhibitors of DNA gyrase (g -) and topoisomerase IV (g +)

Inhibits the function of DNA by preventing supercoiling (g -) or interfering with the separation of strands on replication (g +)

29
Q

Example of quinolones

A

Ciprofloxacin

30
Q

Are quinolones bactericidal or bactereostatic

A

Bactericidal

31
Q

Folic acid

A

Precursors needed by bacteria for growth and DNA synthesis

32
Q

Trimethoprim

A

Analogue folic acid; interferes with folate activity in bacteria (affecting bacterial DNA synthesis) while leaving human DNA alone

Folate antagonist; inhibitor of bacterial dihydrofolate reductase which converts folate to tetrahyrofolate

Usually go-to drug for UTIs

33
Q

Is trimethoprim bactericidal or bactereostatic

A

Bacteriostatic

34
Q

Sulphonamides

A

Antibacterials that are analogues of p-aminobenzoic acid (PABA) and inhibit bacterial growth by competitively inhibiting the enzyme dihydripteroate synthase involved in folate synthesis from PABA

Basically a competitive inhibitor of an enzyme involved in folate synthesis from PABA

Reduces DNA and RNA precursors that are available

35
Q

Metronidazole

A

Antibacterial activated by anaerobic bacteria to cytotoxic products which damages the helical structure of DNA, protein and cell membrane

Used against anaerobic bacteria and protozoa

Commonly used for lower GI bacteria

36
Q

Why not to drink alcohol on metronidazole

A

Metronidazole is an inhibitor of aldehyde dehydrogenase (alcohol is converted into the toxic chemical aldehyde which needs to be metabolised)

37
Q

How to select antibacterials

A

BNF

Different trusts/areas have slightly different recommendations

Take consideration of allergies and the bacteria’s sensitivity

Pharamacokinetics (IV for rapid effects or oral route occasionally)

Drug Interactions

38
Q

Tell patient to complete the course of antibacterials

A

Seriously, this is important >:(

Even if they’re ok before the course is over