Occult bacteremia with nontypeable Haemophilus influenzae.

A 2-year-old boy had occult bacteremia with nontypeable Haemophilus influenzae 6 weeks after receiving H. influenzae type b polysaccharide vaccine. Evaluation of his host defense was normal. As determined by outer membrane protein electrophoresis and Southern hybridization analysis, this strain was not related to type b strains. Its virulence in rats was similar to that of another nontypeable strain and less than that of a type b strain.