Frequency of detection of Hemophilus influenzae type b capsular polysaccharide in infants and children with pneumonia.

Countercurrent immunoelectrophoresis was used to detect H. influenzae type b antigen in sera of 65 consecutive infants and children with clinical and radiographic evidence of pneumonia. Antigenemia was observed in only one patient who also had H. influenzae type b bacteremia. Blood cultures from four other children were positive for H. aphrophilus (one), Streptococcus pneumoniae (two), and an alpha-hemolytic Streptococcus (one). The frequency of pharyngeal colonization with H. influenzae type b was similar in children with or without pneumonia. If H. influenzae type b was the cause of pneumonitis in the children studied, it occurred without bacteremia or antigenemia.