A child was admitted to the hospital with H.influenza meningitis .cefotaxime is preferred over ampicillin because?

Cefotaxime is injectable 3rd generation cephalosporin whereas ampicillin is oral pencillin.therfore,ampicillin must be having higher oral bioavailability as compared to cefotaxime. All beta lactam are bactericidal drugs. Resistance to most starins of H.influenza occurs due to production of beta lactamases.therefore ampicillin is not effective in many patients.now a third generation cephalosporin likr cefotaxime or amoxicillin-clavulinic acid combination is prefered amoung beta lactams.another highly effective drug for H.influenza is azithromycin.(ref.harrison 19th/ep1011