[5] In young infants, a condition known as gray baby syndrome may occur which results in a swollen stomach and low blood pressure.

[medical citation needed] In low-income countries, the WHO no longer recommends only chloramphenicol as first-line to treat meningitis, but recognises it may be used with caution if there are no available alternatives.

[10] During the last decade chloramphenicol has been re-evaluated as an old agent with potential against systemic infections due to multidrug-resistant gram positive microorganisms (including vancomycin resistant enterococci).

[11] In the context of preventing endophthalmitis, a complication of cataract surgery, a 2017 systematic review found moderate evidence that using chloramphenicol eye drops in addition to an antibiotic injection (cefuroxime or penicillin) will likely lower the risk of endophthalmitis, compared to eye drops or antibiotic injections alone.

[12] Chloramphenicol has a broad spectrum of activity and has been effective in treating ocular infections such as conjunctivitis, blepharitis etc.

caused by a number of bacteria including Staphylococcus aureus, Streptococcus pneumoniae, and Escherichia coli.

One example is the ACCoT plasmid (A=ampicillin, C=chloramphenicol, Co=co-trimoxazole, T=tetracycline), which mediates multiple drug resistance in typhoid (also called R factors).

[medical citation needed] As of 2014 some Enterococcus faecium and Pseudomonas aeruginosa strains are resistant to chloramphenicol.

[22] Chloramphenicol may cause bone marrow suppression during treatment; this is a direct toxic effect of the drug on human mitochondria.

[26] This phenomenon occurs in newborn infants because they do not yet have fully functional liver enzymes (i.e. UDP-glucuronyl transferase), so chloramphenicol remains unmetabolized in the body.

It has a large apparent volume of distribution and penetrates effectively into all tissues of the body, including the brain.

Distribution is not uniform, with highest concentrations found in the liver and kidney, with lowest in the brain and cerebrospinal fluid.

[38] Inhibition of CYP2C19 causes decreased metabolism and therefore increased levels of, for example, antidepressants, antiepileptics, proton-pump inhibitors, and anticoagulants if they are given concomitantly.

Inhibition of CYP3A4 causes increased levels of, for example, calcium channel blockers, immunosuppressants, chemotherapeutic drugs, benzodiazepines, azole antifungals, tricyclic antidepressants, macrolide antibiotics, SSRIs, statins, cardiac antiarrhythmics, antivirals, anticoagulants, and PDE5 inhibitors.

[40] Chloramphenicol has been demonstrated a synergistic effect when combined with fosfomycin against clinical isolates of Enterococcus faecium.

It prevents protein chain elongation by inhibiting the peptidyl transferase activity of the bacterial ribosome.

It specifically binds to A2451 and A2452 residues[42] in the 23S rRNA of the 50S ribosomal subunit, preventing peptide bond formation.

[43] Chloramphenicol directly interferes with substrate binding in the ribosome, as compared to macrolides, which sterically block the progression of the growing peptide.

[44][45][46] Chloramphenicol was first isolated from Streptomyces venezuelae in 1947 and in 1949 a team of scientists at Parke-Davis including Mildred Rebstock published their identification of the chemical structure and their synthesis.

[8]: 26 [47][48] In 1972, Senator Ted Kennedy combined the two examples of the Tuskegee Syphilis Study and the 1958 Los Angeles Infant Chloramphenicol experiments as initial subjects of a Senate Subcommittee investigation into dangerous medical experimentation on human subjects.

Roussel stopped production of oily chloramphenicol in 1995; the International Dispensary Association Foundation has manufactured it since 1998, first in Malta and then in India from December 2004.

[61] Chloramphenicol is used in topical preparations (ointments and eye drops) for the treatment of bacterial conjunctivitis.

Isolated case reports of aplastic anaemia following use of chloramphenicol eyedrops exist, but the risk is estimated to be of the order of less than one in 224,716 prescriptions.