Meningitis due to an unusual type of Haemophilus influenzae.

An infant was admitted to hospital with suspected meningitis. Haemophilus influenzae type 'a' was isolated from cerebrospinal fluid (C.S.F.) and blood. Haemophilus meningitis due to types other than type 'b' is rare, and only a few due to type 'a' have so far been recorded. Investigations of the family are included together with a discussion of the implications for the diagnostic bacteriologist.