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Antibiotics > Fluroquinones > Flashcards

Fluroquinones Flashcards

1
Q

Front

A

Back

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2
Q

Fluoroquinolones: Drugs

A

Ciprofloxacin, ofloxacin; respiratory fluoroquinolones: levofloxacin, moxifloxacin.

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3
Q

Fluoroquinolones: Mechanism

A

Inhibit prokaryotic topoisomerase II (DNA gyrase) and topoisomerase IV. Bactericidal. Oral absorption is markedly decreased by concurrent ingestion of divalent cations (e.g., dairy, antacids).

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4
Q

Fluoroquinolones: Clinical Use

A

Effective against gram ⊝ rods of urinary and GI tracts (including Pseudomonas), some gram ⊕ organisms, otitis externa, and community-acquired pneumonia.

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5
Q

Fluoroquinolones: Adverse Effects

A
  • GI upset, superinfections, skin rashes, headache, dizziness.
  • Less commonly: leg cramps, myalgias.
  • Tendonitis or tendon rupture (especially in patients > 60 years old or on prednisone).
  • Contraindicated in pregnancy, breastfeeding, and in children < 18 years old due to possible cartilage damage.
  • May prolong QT interval.
    Mnemonic: ‘Fluoroquinolones hurt attachments to your bones.’
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6
Q

Fluoroquinolones: Mechanism of Resistance

A
  • Chromosome-encoded mutation in DNA gyrase.
  • Plasmid-mediated resistance.
  • Efflux pumps.
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7
Q

Daptomycin: Mechanism

A

Lipopeptide that disrupts gram ⊕ bacterial cell membranes by creating transmembrane channels.

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8
Q

Daptomycin: Clinical Use

A

Effective against S aureus skin infections (especially MRSA), bacteremia, infective endocarditis, and VRE.

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9
Q

Daptomycin: Adverse Effects

A
  • Myopathy.
  • Rhabdomyolysis.
    Note: Not used for pneumonia (inactivated by surfactant). Mnemonic: ‘Dapto-myo-skin’—used for skin infections but can cause myopathy.
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10
Q

Metronidazole: Mechanism

A

Forms toxic free radical metabolites in bacterial cells, damaging DNA. Bactericidal and antiprotozoal.

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11
Q

Metronidazole: Clinical Use

A

Treats:
- Giardia.
- Entamoeba.
- Trichomonas.
- Gardnerella vaginalis.
- Anaerobes (Bacteroides, C difficile).
- Can replace amoxicillin in H pylori ‘triple therapy’ for penicillin-allergic patients.
Mnemonic: ‘GET GAP on the Metro’—treats anaerobic infections below the diaphragm (vs clindamycin for above diaphragm).

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12
Q

Metronidazole: Adverse Effects

A
  • Disulfiram-like reaction with alcohol (flushing, tachycardia, hypotension).
  • Headache.
  • Metallic taste.
  • Can cause tendonitis or tendon rupture in patients > 60 years old or on prednisone.
    Note: Ciprofloxacin inhibits cytochrome P-450.
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13
Q

Linezolid: Mechanism

A

Inhibits protein synthesis by binding to the 23S rRNA of the 50S ribosomal subunit, preventing the formation of the initiation complex.

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14
Q

Linezolid: Clinical Use

A

Effective against gram ⊕ species, including MRSA and VRE.

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15
Q

Linezolid: Adverse Effects

A
  • Myelosuppression (especially thrombocytopenia).
  • Peripheral neuropathy.
  • Serotonin syndrome (due to partial MAO inhibition).
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16
Q

Linezolid: Mechanism of Resistance

A

Point mutation of ribosomal RNA.

17
Q

Macrolides: Drugs

A

Azithromycin, clarithromycin, erythromycin.

18
Q

Macrolides: Mechanism

A

Inhibit protein synthesis by blocking translocation (‘macroslides’); bind to the 50S ribosomal subunit. Bacteriostatic.

19
Q

Macrolides: Clinical Use

A

Used for atypical pneumonias (Mycoplasma, Chlamydia, Legionella), STIs (Chlamydia), gram ⊕ cocci (streptococcal infections in penicillin-allergic patients), and B pertussis.

20
Q

Macrolides: Adverse Effects

A

MACRO:
- Gastrointestinal Motility issues.
- Arrhythmia due to prolonged QT interval.
- Acute cholestatic hepatitis.
- Rash.
- Eosinophilia.
- Increases serum levels of theophylline and oral anticoagulants. Clarithromycin and erythromycin inhibit cytochrome P-450.

21
Q

Macrolides: Mechanism of Resistance

A

Methylation of the 23S rRNA-binding site prevents drug binding.

22
Q

Polymyxins: Drugs

A

Colistin (polymyxin E), polymyxin B.

23
Q

Polymyxins: Mechanism

A

Cationic polypeptides that bind to phospholipids on the cell membrane of gram ⊝ bacteria, disrupting cell membrane integrity, causing leakage of cellular components, and cell death.

24
Q

Polymyxins: Clinical Use

A

Used as salvage therapy for multidrug-resistant gram ⊝ bacteria (e.g., P aeruginosa, E coli, K pneumoniae). Polymyxin B is a component of triple antibiotic ointments for superficial skin infections.

25
Q

Polymyxins: Adverse Effects

A
  • Nephrotoxicity.
  • Neurotoxicity (e.g., slurred speech, weakness, paresthesias).
  • Respiratory failure.
26
Q

Sulfonamides: Drugs

A

Sulfamethoxazole (SMX), sulfisoxazole, sulfadiazine.

27
Q

Sulfonamides: Mechanism

A

Inhibit dihydropteroate synthase, thereby inhibiting folate synthesis. Bacteriostatic (bactericidal when combined with trimethoprim).

28
Q

Sulfonamides: Clinical Use

A

Effective against gram ⊕, gram ⊝, and Nocardia. TMP-SMX is used for simple UTIs.

29
Q

Sulfonamides: Adverse Effects

A
  • Stevens-Johnson syndrome.
  • Urticaria.
  • Liver damage.
  • Folate deficiency.
  • Optic neuritis.
  • Nephrotoxicity.
  • Agranulocytosis.
  • Hemolysis if G6PD deficient.
  • Kernicterus in infants.
30
Q

Sulfonamides: Mechanism of Resistance

A

Resistance occurs through altered enzyme (dihydropteroate synthase), reduced uptake, or increased PABA synthesis.

31
Q

Dapsone: Mechanism

A

Similar to sulfonamides but structurally distinct. Inhibits dihydropteroate synthase.

32
Q

Dapsone: Clinical Use

A

Used for leprosy (both lepromatous and tuberculoid forms) and as prophylaxis or treatment for Pneumocystis jirovecii when combined with TMP.

33
Q

Dapsone: Adverse Effects

A
  • Hemolysis if G6PD deficient.
  • Methemoglobinemia.
  • Agranulocytosis.
34
Q

Trimethoprim: Mechanism

A

Inhibits bacterial dihydrofolate reductase, making it bacteriostatic.

Antibiotics (2 decks)

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