Post immunization Hib antigen detection in the CSF of a patient with meningococcal meningitis

We report a case of meningococcal meningitis where the cerebrospinal fluid was negative for neisseria meningitidis but positive for haemophilus influenzae type b by rapid antigen detection test. We believe that this was due to prior immunization with haemophilus influenzae type b vaccine. We recommend caution in interpretation of the rapid antigen detection tests especially in patients who had been vaccinated against organisms screened by these tests