Haemophilus influenzae has been isolated from the CSF of a two year old boy suffering from meningitis.The strain is beta-lactamase producing and resistant to chloramphenicol.The most appropriate antimicrobial in such a situation is:

• A. Ciprofloxacin
• B. Trimethoprim-sulphamethoxazole combination
• C. Vancomycin
• D. Third-generation cephalosporin