Haemophilus influenzae non-type b infections in children.

During a four-year surveillance period in a tertiary care children's hospital, nine children experienced 11 episodes of Haemophilus influenzae non-type b invasive infections, representing 9% of all invasive H influenzae infections. Of these nine children, two had lymphoproliferative disorders; one had immunoglobulin subclass deficiency; one had severe congenital heart disease, with chronic heart failure; two had cerebrospinal fluid leaks; and two were premature neonates whose mothers had prolonged rupture of amniotic membranes. Only one child had no evidence of an underlying condition that might predispose him to infection with these ordinarily nonpathogenic organisms. Three of the isolates were serotype f, one was serotype e, and the remaining seven were nontypable, with types a through f antisera. Thus, the majority of children experiencing invasive H influenzae non-type b infections appear to have a predisposing medical condition. To aid in detecting these unusual infections, all H influenzae isolates from otherwise sterile body sites should be serotyped, and those children with non-type b isolates should be evaluated for a possible predisposing underlying illness.