Counterimmunoelectrophoresis in the diagnosis of Hemophilus influenzae pleural effusion.

A child with a sterile pleural effusion resulting from an infection with Hemophilus influenzae type b (Hi b) is described. The diagnosis was established by use of counterimmunoelectrophoresis (CIE). The alarming increase in incidence of pneumonia due to Hi b is noted, as is the large number of associated pleural effusions. CIE provides a rapid, reliable, and sensitive means by which to establish the exact etiology of such bacterial infections so that optimal antibiotic therapy can be started promptly.