<prompt> H. influenzae has been isolated from the CSF of a 2 year old boy suffering from meningitis. The strain is beta lactamase producing and resistant to chloramphenicol, The most appropriate antimicrobial isTrimethoprim -- suiphamethoxazole combinationCiprofloxacinThird generation cephalosporinVancomycin  <response>: HI Inlluenzae type b produces J3 lactamases and therefore are resistant to ampicillin. These 3 lactamase producing strains remain sensitive to the extended spectrum cephalosporins Ceftriaxone or cefotaxime IV are used as a single agents Infections caused by ampicillin - resistant strains can be treated with 1. Trimethoprim - sulfamethoxazole 2. Amoxicillin I clavulanic acid 3. Extended spectrum cephalosporins 4. Azithromycin and clarithromycin Floraquin lones are highly active against H. influenzae but are not currently recommended for the treatment of children or pregnailt women because of possible effects on aicular cailage 