What is the initial empiric therapy for acute bacterial meningitis in adults?

The initial empiric therapy for acute bacterial meningitis in adults typically includes a third-generation cephalosporin, such as ceftriaxone or cefotaxime. This choice is essential because third-generation cephalosporins have a broad spectrum of activity against the most common pathogens associated with bacterial meningitis, including Streptococcus pneumoniae and Neisseria meningitidis.

In the context of empiric therapy, it is critical to choose an antibiotic that can effectively penetrate the blood-brain barrier, which third-generation cephalosporins do. Additionally, their use is supported by clinical guidelines recommending this class of antibiotics due to their efficacy and safety profile in treating serious infections like meningitis.

While high-dose penicillin G can be effective against certain strains of Streptococcus pneumoniae, it is not the broad-spectrum agent recommended as the initial therapy on its own. Vancomycin is often added to cover resistant strains of these bacteria but is not typically the sole empiric therapy. Macrolide antibiotics are not used for treating bacterial meningitis due to their inadequate coverage of the common pathogens involved.