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

Antibiotics 2 Flashcards

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
What conditions is **rifampicin** used to treat? [2]
1. TB (in combination therapy) 2. serious gram +ve infection (in combination therapy)
26
What does a typical TB lesion look like and where is it usually found? [3]
1. epithelioid granuloma with central caseation necrosis 2. most common site = alveolar macrophages in subpleural regions of the lung
27
Why is TB difficult to treat? [3]
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
How is the treatment of TB tailored to maximise efficacy? [2]
1. **prolonged courses** of treatment (usually 6 months) 2. use **combination therapy** (to prevent resistance and kill both growing and resting organisms)
29
What are the 4 drugs used to treat TB and describe the effect of each? [8]
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
What does inhibition of the folate metabolism pathway lead to? [2]
1. impaired nucleotide synthesis 2. + therefore impaired DNA replication
31
Name the 2 antibiotics that inhibit folate synthesis [2]
1. trimethoprim 2. co-trimoxazole (combination of trimethoprim and sulphamethoxazole)
32
How is trimethoprim administered? [1]
orally
33
Which classes of bacteria is trimethoprim effective at targeting? [2]
1. gram +ve 2. gram -ve
34
What are the potential toxic complications of trimethoprim? [4]
1. elevation of serum creatinine 2. elevation of serum K+ * problematic in patients with chronic renal impairment 3. rash 4. GI disturbance
35
What are the potential toxic complications of co-trimoxazole? [2]
1. bone marrow suppression 2. Stevens Johnson syndrome (rare, severe condition affecting skin & mucous membranes)
36
What antibiotic is used to treat an **uncomplicated UTI**? [1]
trimethoprim
37
What antibiotic is used to treat a **complicated UTI**? [1]
ciprofloxacin
38
What antibiotics are used to treat someone **severely unwell** with UTI? [2]
1. amoxicillin 2. gentamicin
39
What antibiotics are considered safe for use during pregnancy? [3]
1. most beta-lactams 2. macrolides 3. anti-tuberculants
40
What antibiotics are considered **unsafe** for use during pregnancy and why? [10]
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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