Binds to 50S ribosomal subunit, inhibiting protein synthesis.

Note: Binds to similar site on 50S ribosome as macrolides.

Macrolides

Chloramphenicol

Linezolid

Lincosamides (clindamycin)

Tetracyclines and tigecyline

Aminogylcosides

Gram+, Gram-, aerobic and anaerobic. 

Mycoplasma, Chlamydia, Rickettsia

Bacteriostatic.

Serious adverse effects (bone marrow toxicity)

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

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).

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).