Antibiotics Flashcards

1
Q

Name 5 clinical indications for antimicrobials to be prescribed

A
  1. Periapical or periodontal disease
  2. Cellulitis
  3. Sinusitis
  4. Oral candidiasis
  5. Angular cheilitis
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2
Q

What is the major issue with antibiotics?

A

Antimicrobial resistance

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3
Q

What is the most commonly prescribed type of antibiotic?

A

Penicillins

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4
Q

Name 3 main types of antimicrobials

A
  1. Antibiotics
  2. Antifungals
  3. Antivirals
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5
Q

Name 3 β-lactam drugs which are penicillin based

A
  1. Amoxicillin
  2. Penicillin V
  3. Flucloxacillin
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6
Q

What are 3 possible targets for chemotherapeutic agents?

A
  1. Cell wall
  2. Processes of protein synthesis
  3. Toxicity limited to low oxygen environments
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7
Q

What are the 2 monomers which build a bacterial cell wall?

A
  1. N-acetylglucosamine (NAG)

2. N-acetylmuramic acid (NAMA)

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8
Q

What is the significance of the enzyme which binds strands of monomers together to form a bacterial cell wall?

A

Transpeptidase is the protein which penicillin binds to

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9
Q

Name 2 groups of drugs which are cell wall active agents

A
  1. β-lactams

2. Glycopeptides

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10
Q

Name 4 types of β-lactam drugs

A
  1. Penicillins
  2. Cephalosporins
  3. Monobactams
  4. Carbapenems
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11
Q

Name 2 glycopeptide antibiotic drugs

A
  1. Vancomycin

2. Teicoplanin

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12
Q

Describe the structural properties of penicillin as a drug

A
  • β-lactam ring found in all penicillin drugs
  • Ring binds with enzyme and prevents cross linking of chains of the cell wall
  • Side chains contribute to variety of drugs
  • Penicillin based drugs will all have similar effects due to the β-lactam ring
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13
Q

Describe the ADME of penicillins

A
  • Variable stability to gastric acids so variable oral bioavailability
  • 50% protein bound and low concentration in serous fluids
  • Variable half life
  • Entirely excreted renally
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14
Q

Name 4 adverse effects of penicillin

A
  1. GI upset
  2. Candidiasis
  3. Non IgE mediated rashes
  4. Reproducibility of reaction amongst other penicillins
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15
Q

Describe a true allergic reaction to penicillin

A

IgE mediated hypersensitivity causing angio-oedema, anaphylaxis, urticarial rash. There is immediate onset and cross reactivity amongst all penicillins

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16
Q

What are 3 ways an antibiotic can become resistant to penicillin?

A
  1. Altered target site for the antimicrobial
  2. Alteration of the uptake or output of antimicrobial agents
  3. Enzymatic degradation of antimicrobial agents
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17
Q

Why may β-lactam drugs be combined with β-lactamase inhibitors?

A

β-lactamase inhibitors limit the action of β-lactamase enzymes so increase activity of an antibiotic

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18
Q

What is the main penicillin combined with β-lactamase inhibitor drug prescribed?

A

Co-Amoxiclav (amoxicillin/clavulanate)

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19
Q

Name a tetracycline drug

A

Doxycycline

20
Q

What 4 reasons would doxycycline be used?

A
  1. Periodontitis
  2. Refractory or severe forms of oral infections
  3. Sinusitis in the case of penicillin allergy
  4. Rinsed for aphthous ulcers
21
Q

Describe the ADMA of tetracyclines

A
  • Oral drugs
  • Rapidly absorbed but residual in gut
  • Reduced absorption with metallic ions
  • Widely distributed into tissues
  • Doxycycline mainly biliary excretion (can be renal and gut)
22
Q

Why is there reduced absorption if tetracyclines are taken with metallic ions?

A

Tetracycline will bind with calcium (etc) and reduce the amount of drug which can move into the blood stream

23
Q

What is the mode of action of tetracyclines?

A

Biding to the 30S subunit, preventing entry of amino acetyl tRNA complexes

24
Q

Describe 4 adverse effects of tetracyclines

A
  1. Staining of teeth (developing teeth)
  2. GI disturbance
  3. Candidiasis
  4. Photosensitivity
25
Q

Name 2 macrolide drugs which are prescribed as classic alternatives to penicillin

A
  1. Erythromycin

2. Clarithromycin

26
Q

Describe the ADME of macrolides

A
  • Absorption is generally good
  • Wide distribution and tissue concentrations
  • Half life much longer in clarithromycin than erythromycin
  • Broken down in body but a small amount excreted unchanged in urine
27
Q

Why is clarithromycin absorption generally better than erythromycin?

A

It is given as an estolate salt

28
Q

What is the mode of action of macrolides?

A

Binds to 50S subunit, preventing translocation of the next amino acid onto the nascent peptide chain

29
Q

What are 3 adverse effects of macrolides?

A
  1. GI upset
  2. Acts as hepatic enzyme inhibitor, so can potentiate effects of other drugs e.g. warfarin
  3. Rare causes of cholestatic hepatitis
30
Q

To what group of drugs does clindamycin belong?

A

Lincosamide group

31
Q

Name 3 situations where clindamycin may be used

A
  1. Recommended for endocarditis prophylaxis if penicillin allergic
  2. Ludwig’s angina
  3. Cellulitis
32
Q

Describe ADME of clindamycin

A
  • High bioavailability, with almost complete absorption
  • Widely distributed including into bone and joints
  • Metabolized by liver and excreted in bile and urine
  • Small amount excreted unchanged in urine
33
Q

What is the mode of action of clindamycin?

A

Binds to 50S subunit, preventing translocation of the next amino acid onto the nascent peptide chain

34
Q

Name 4 adverse affects of clindamycin

A
  • Diarrhoea
  • Pseudomembranous colitis
  • Nausea
  • Rare cases of exfoliative dermatitis
35
Q

Why can diarrhoea be a side effect of taking clindamycin?

A

Action on anaerobic bacteria

36
Q

What type of drug can limit toxicity to low oxygen environments?

A

Nitroimidazoles

37
Q

What is the name of the primary nitroimidazole prescribed in dentistry?

A

Metronidazole

38
Q

What 4 things may metronidazole be used for?

A
  1. Pericoronitis
  2. ANUG
  3. Periodontitis
  4. Periapical disease
39
Q

Describe the ADME of metronidazole

A
  • Well absorbed and high oral bioavailability
  • Distributed widely including into tissue spaces and abscess cavities
  • Metabolized by liver
  • Large quantity is secreted into the colon following upper GI absorption
40
Q

What is the mode of action of metronidazole?

A

It is a pro-drug so in low oxygen conditions gets reduced to a metabolite toxic to DNA, causing inhibition of DNA synthesis and strand breakdown

41
Q

What are 4 adverse effects of metronidazole?

A
  • GI upset
  • Nausea
  • Disulfiram like effect (inhibits alcohol metabolism)
  • Inhibits hepatic metabolism of warfarin
42
Q

Name 4 general adverse effects from antimicrobials

A
  1. Stevens-Johnson syndrome
  2. Intrinsic staining
  3. Oral candidiasis
  4. Taste disturbance
43
Q

What 3 groups of antimicrobials are likely to cause Stevens-Johnson syndrome?

A
  1. Antibacterial agents
  2. Antiretroviral agents
  3. Sulphonamide agents
44
Q

What type of antibiotic is likely to cause intrinsic staining?

A

Tetracyclines

45
Q

What 2 antibiotics are likely to cause taste disturbances?

A
  1. Metronidazole

2. Clarithromycin