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Week 6 - Clinical Microbiology & Infections 1 > Antibiotics 2 > Flashcards

Antibiotics 2 Flashcards

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1
Q

What are the 4 physiological mechanisms that antibiotics tend to target? [4]

A
  1. Cell wall biosynthesis
  2. Protein biosynthesis
  3. DNA and RNA replication
  4. Folate metabolism
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2
Q

Name 3 protein synthesis inhibitors that target the 50S ribosomal subunit [3]

A
  1. Macrolides
  2. Clindamycin
  3. Chloramphenicol
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3
Q

Name the 3 types of macrolides [3]

A
  1. Erythromycin
  2. Clarithromycin
  3. Azithromycin
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4
Q

Name 2 protein synthesis inhibitors that target the 30S ribosomal subunit [2]

A
  1. aminoglycosides
  2. tertracyclines
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5
Q

Give an example of an aminoglycoside antibiotic [1]

A

gentamicin

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6
Q

Give an example of a tetracycline antibiotic [1]

A

doxycycline

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7
Q

What are the bacteria that macrolides (in particular clarithromycin) are effective at targeting (incl. which class each bacteria is in)? [10]

A
  1. gram +ves
    • streptococcus
    • staphylococcus
    • enterococcus
  2. respiratory gram -ves
    • neisseria
    • haemophilus
  3. atypicals
    • legionella
    • mycoplasma
    • coxiella
    • chlamydia
    • chlamydophila
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8
Q

What are the potential adverse effects of macrolides (in particular clarithromycin)? [4]

A
  1. diarrhoea
  2. vomiting
  3. QT prolongation
  4. hearing loss with long-term use
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9
Q

Why is clarithromycin so susceptible to drug interactions? [1]

A

it is a potent inhibitor of cytochrome P450 enzymes

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10
Q

Which 3 drugs in particular should you avoid prescribing alongside clarithromycin? [3]

A
  1. simvastatin
  2. atorvastatin
  3. warfarin
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11
Q

Which bacteria is clindamycin effective at targeting (incl. which class each bacteria is in)? [4]

A
  1. gram +ve
    • streptococcus
    • staphylococcus
    • (not enterococcus)
  2. anaerobes
    • bacteroides
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12
Q

What are the 4 C. differgic antibiotics? [4]

A
  1. clindamycin
  2. co-amoxiclav
  3. cephalosporins
  4. ciprofloxacin
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13
Q

Chloramphenicol has an excellent broad spectrum of activity, but it is very toxic. What are the potential complications? [3]

A
  1. bone marrow suppression
  2. aplastic anaemia
  3. optic neuritis
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14
Q

Describe the mechanism of action of the aminoglycoside gentamicin [2]

A
  1. reversibly binds to the 30S ribosome
  2. bacteriostatic action
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15
Q

What are the potential toxic complications of gentamicin? [7]

A
  1. nephrotoxicity
  2. ototoxicity
    • hearing loss
    • loss of balance
    • oscillopsia (severe problem with vision)
  3. neuromuscular blockade
    • usually only significant in myasthenia gravis
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16
Q

Which bacteria is gentamcin effective at targeting (incl. which class each bacteria is in)? [7]

A
  1. gram -ve
    • E. coli
    • other coliforms
    • neisseria
    • haemophilus
    • pseudomonas
  2. gram +ve
    • staphylococcus
    • streptococcus
    • (not enterococcus)
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17
Q

Why should you avoid giving tetracyclines (like doxycycline) to children and pregnant women? [2]

A
  1. risk of bone abnormalities and
  2. tooth discolouration
18
Q

Which bacteria is doxycycline effective at targeting (incl. which class each bacteria is in)? [10]

A
  1. gram +ve
    • streptococcus
    • staphylococcus
    • enterococcus
  2. gram -ve
    • neisseria
    • haemophilus
  3. atypicals
    • rickettsia
    • mycoplasma
    • coxiella
    • chlamydia
    • chlamydophila
19
Q

Name 2 antibiotics that target DNA repair and replication [2]

A
  1. quinolones
  2. rifampicin
20
Q

Name the 2 types of quinolones [2]

A
  1. ciprofloxacin
  2. levofloxacin
21
Q

Which bacteria is the quinolone ciprofloxacin effective at targeting (incl. which class each bacteria is in)? [12]

A
  1. gram -ve
    • pseudomonas
    • haemophilus
    • neisseria
    • E. coli
    • other coliforms
  2. gram +ve (less effective)
    • streptococcus
    • staphylococcus
  3. atypicals
    • legionella
    • mycoplasma
    • coxiella
    • chlamydia
    • chlamydophila
22
Q

What conditions is ciprofloxacin used to treat? [2]

A
  1. UTIs
  2. abdominal infections
23
Q

Which conditions is levofloxacin used to treat? [1]

A

respiratory tract infections (due to stronger gram +ve activity than ciprofloxacin)

24
Q

What are the potential toxic complications of levofloxacin? [3]

A
  1. gastrointestinal toxicity
  2. QT prolongation
  3. tendonitis
25
Q

What conditions is rifampicin used to treat? [2]

A
  1. TB (in combination therapy)
  2. serious gram +ve infection (in combination therapy)
26
Q

What does a typical TB lesion look like and where is it usually found? [3]

A
  1. epithelioid granuloma with central caseation necrosis
  2. most common site = alveolar macrophages in subpleural regions of the lung
27
Q

Why is TB difficult to treat? [3]

A
  1. in order to reach their targets in intracellular bacilli, anti-TB drugs must overcome several barriers to enter a TB lesion, the most problematic of these is reduced vascularisation
  2. TB lesions also have dense bacterial populations (high bacterial burden)
  3. these bacteria tend to be slow growing which can influence the permeability of the pathogen to small drug molecules
28
Q

How is the treatment of TB tailored to maximise efficacy? [2]

A
  1. prolonged courses of treatment (usually 6 months)
  2. use combination therapy (to prevent resistance and kill both growing and resting organisms)
29
Q

What are the 4 drugs used to treat TB and describe the effect of each? [8]

A
  1. rifampicin
    • bactericidial against slowly replicating organisms in necrotic areas
  2. isoniazid
    • bactericidal against fast growing mycobacteria
  3. pyrazinamide
    • bactericidal against slowly growing mycobacteria intracellularly
  4. ethambutol
    • bacteriostatic against slow growing mycobacteria
30
Q

What does inhibition of the folate metabolism pathway lead to? [2]

A
  1. impaired nucleotide synthesis
    • therefore impaired DNA replication
31
Q

Name the 2 antibiotics that inhibit folate synthesis [2]

A
  1. trimethoprim
  2. co-trimoxazole (combination of trimethoprim and sulphamethoxazole)
32
Q

How is trimethoprim administered? [1]

A

orally

33
Q

Which classes of bacteria is trimethoprim effective at targeting? [2]

A
  1. gram +ve
  2. gram -ve
34
Q

What are the potential toxic complications of trimethoprim? [4]

A
  1. elevation of serum creatinine
  2. elevation of serum K+
    • problematic in patients with chronic renal impairment
  3. rash
  4. GI disturbance
35
Q

What are the potential toxic complications of co-trimoxazole? [2]

A
  1. bone marrow suppression
  2. Stevens Johnson syndrome (rare, severe condition affecting skin & mucous membranes)
36
Q

What antibiotic is used to treat an uncomplicated UTI? [1]

A

trimethoprim

37
Q

What antibiotic is used to treat a complicated UTI? [1]

A

ciprofloxacin

38
Q

What antibiotics are used to treat someone severely unwell with UTI? [2]

A
  1. amoxicillin
  2. gentamicin
39
Q

What antibiotics are considered safe for use during pregnancy? [3]

A
  1. most beta-lactams
  2. macrolides
  3. anti-tuberculants
40
Q

What antibiotics are considered unsafe for use during pregnancy and why? [10]

A
  1. tetracyclines
    • bone/tooth abnormalities
  2. trimethoprim
    • neural tube defects (1st trimester)
  3. nitrofurantoin
    • haemolytic anaemia (3rd trimester)
  4. aminoglycosides
    • ototoxicity (2nd/3rd trimester)
  5. quinolones
    • bone/joint abnormalities

Week 6 - Clinical Microbiology & Infections 1 (13 decks)

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