Chloramphenicol

Chloramphenicol

• Gram-positive and gram-negative cocci and bacilli (including anaerobes)

• Rickettsia, Mycoplasma, Chlamydia, and Chlamydophila species

Because of bone marrow toxicity, the availability of alternative antibiotics, and the emergence of resistance, chloramphenicol is no longer an antibiotic of choice for any infection, except for

• Serious infections due to a few multidrug-resistant bacteria that remain susceptible to this antibiotic

• Plague meningitis or endophthalmitis because other plague medications penetrate these spaces poorly

chloramphenicol has poor bactericidal activity against these strains.

• Bone marrow depression (most serious)

• Nausea, vomiting, and diarrhea

• Gray baby syndrome (in neonates)

There are 2 types of bone marrow depression:

• Reversible dose-related interference with iron metabolism: This effect is most likely with high doses or prolonged treatment or in patients with a severe liver disorder.

• Irreversible idiosyncratic aplastic anemia: This anemia occurs in < 1/25,000 treated patients. It may not develop until after therapy is stopped. Chloramphenicol should not be used topically because small amounts may be absorbed and, rarely, cause aplastic anemia.

Hypersensitivity reactions are uncommon. Optic and peripheral neuritis may occur with prolonged use.

The neonatal gray baby syndrome, which involves hypothermia, cyanosis, flaccidity, and circulatory collapse, is often fatal. The cause is high blood levels, which occur because the immature liver cannot metabolize and excrete chloramphenicol. To avoid the syndrome, clinicians should not give infants ≤ 1 month of age > 25 mg/kg/day initially, and doses should be adjusted based on blood levels of the medication.