Which agent is the first line in the treatment of bacterial meningitis in adults?

Ceftriaxone is the first-line treatment for bacterial meningitis in adults due to its broad-spectrum activity against common bacterial pathogens responsible for the condition, particularly Streptococcus pneumoniae and Neisseria meningitidis. This cephalosporin antibiotic penetrates well into the central nervous system, allowing it to effectively reach therapeutic concentrations in the cerebrospinal fluid, which is crucial for treating infections in that area.

In the context of bacterial meningitis, immediate initiation of effective antimicrobial therapy is essential, as the condition can rapidly lead to severe complications or death. Ceftriaxone not only provides effective coverage but also has a favorable safety profile and long half-life, making it suitable for high-dose administration in hospital settings. It can be used alone or in combination with other agents, such as vancomycin, which is often added to cover for resistant pneumococci when there is concern for penicillin resistance.

The other agents mentioned, while effective against various bacterial infections, do not serve as first-line treatments for bacterial meningitis in adults due to limitations in spectrum of activity or CNS penetration.