Chloramphenicol

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Summary

Chloramphenicol is an antibiotic that works by binding the 50S subunit of bacterial ribosomes to prevent bacterial protein synthesis. The drug is used as a second or third line therapy for bacterial meningitis and to treat rickettsial diseases. Adverse effects of chloramphenicol include gray baby syndrome, anemia which is dose-dependent, and aplastic anemia which is dose independent.

Key Points

  • Chloramphenicol
    • Mechanism
      • Reversibly binds 50S subunit of bacterial ribosomes
        • Blocks peptidyltransferase and inhibits bacterial protein synthesis
      • Bacteriostatic
    • Clinical Use
      • Meningitis
        • e.g. H. influenzae, N. meningitidis, S. pneumoniae
      • Rickettsial diseases
    • Adverse Effects
      • Anemia (dose-dependent)
        • Anemia, leukopenia, thrombocytopenia are all possible
        • Reversible by stopping medication
      • Aplastic anemia (dose-independent)
        • Thought to result from autoimmunity induced by drug
        • Usually severe and fatal without bone marrow transplantation
      • Gray-baby syndrome
        • Presents in babies as gray skin, vomiting, lethargy, and cardiorespiratory suppression
        • Premature infants lack liver UDP-glucuronosyltransferase and cannot metabolize the drug, leading to toxic accumulation
    • Resistance
      • Plasmid-encoded acetyltransferase inactivates the drug