A 6-year-old girl is diagnosed with meningitis. A lumbar puncture reveals numerous neutrophils and gram-negative diplococci. She is admitted to the hospital for antibiotic treatment, which is complicated by the fact that she is known to be allergic to b-lactams. What is the mechanism of action of the alternative drug of choice to treat this infant's meningitis?

The girl in the vignette most likely has Neisseria meningitidis meningitis. The drug of choice is ceftriaxone, which is contraindicated by the child's known b-lactam allergy due to cross-hypersensitivity. The alternative drug of choice is chloramphenicol, which inhibits formation of the peptide bond (c) through inhibition of the transpeptidase reaction. Meropenem, a second alternative, is also a b-lactam with cross-hyper-sensitivity. Tetracycline, which blocks tRNA binding to the A site (a), is not used to treat meningitis and should not be used in children under 10. Aminoglycosides, which cause misreading of mRNA (b) and result in premature termination (e) of translation, as well as blocking initiation of protein synthesis, are not generally used to treat meningitis except in cases caused by Listeria. Macrolides prevent translocation (d) and are not used to treat meningitis.