Term
How does chloramphenicol work? |
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Definition
Binds to 50S ribosomal subunit, inhibiting protein synthesis.
Note: Binds to similar site on 50S ribosome as macrolides. |
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Term
Which antibiotics work by binding to the 50S ribosomal subunit? |
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Definition
Macrolides
Chloramphenicol
Linezolid
Lincosamides (clindamycin) |
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Term
Which antibiotics work by binding to the 30S ribosomal subunit? |
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Definition
Tetracyclines and tigecyline
Aminogylcosides |
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Term
What are targets of chloramphenicol? |
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Definition
Gram+, Gram-, aerobic and anaerobic.
Mycoplasma, Chlamydia, Rickettsia |
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Term
Is chloramphenicol bacteriostatic or bactericidal? |
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Definition
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Term
Why is chloramphenicol rarely used? |
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Definition
Serious adverse effects (bone marrow toxicity) |
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Term
What are adverse effects of chloramphenicol? |
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Definition
Serious side effects limit use.
Bone Marrow Toxicity:
-- Bone marrow suppression (reversible): due to inhibition of mitochondrial protein synthesis
-- Aplastic anemia (rare, but fatal): onset weeks to months after drug is stopped
-- Higher risk of developing leukemia later in life
Gray Baby Syndrome in newborns (40% fatal)
-- Only with chloramphenicol; due to mitochondrial protein synthesis inhibition (according to Shewach)
Note: Textbooks says it's due to lack of liver enzymes that metabolize drug, leading to toxic buildup
-- Severe GI and respiratory disturbances |
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Term
How is chloramphenicol eliminated? |
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Definition
Glucouronidation in liver to inactivate, then excreted renally.
Note: Neonates lack UDP-glucuronyl transferase and can't eliminate chloramphenicol and its toxic metabolites. This leads to Gray Baby Syndrome (Shewach says Gray Baby Syndrome is due to mitochondrial protein synthesis inhibition). |
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Term
What are clinical uses of chloramphenicol? |
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Definition
Almost never used due to risk of serious adverse effects (aplastic anemia).
Used for staphylococcal and unknown mixed brain abscesses (great CSF penetration). Alternative treatment for meningitis caused by N. meningitidis, S. pneumoniae, H. influenzae if patient is allergic to penicillins/cephalosporins (activity is somehow cidal against these organisms). |
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