Cellulitis due to Haemophilus influenzae type B. Antigenemia and antibody responses.

The techniques of serum countercurrent immunoelectrophoresis, hemagglutinating (HA), and bactericidal (BC) antibody determinations were applied to seven patients with Haemophilus influenzae type B cellulitis. Capsular antigen was detected (greater than or equal to 10 ng/ml) in two patients at the time of admission and was found in two additional patients two days following hospitalization. Antibody responses in the patients with cellulitis were deficient, similar to those in children under 2 years of age with H influenzae type B meningitis. One of the patients with cellulitis had HA and BC antibody present in convalescent serum, and two additional patients demonstrated BC activity. The clinical presentations of our patients were typical except that violaceous discoloration of overlying skin was noted in only one of the seven. Two additional patients had atypical facial swelling that closely resembled angioneurotic edema and initially led to incorrect diagnosis. Countercurrent immunoelectrophoresis may be helpful in the diagnosis of patients with Haemophilus cellulitis, particularly if serial serum determinations are performed. Bacterial cultures obtained from blood and aspirates of the lesion appear to be more sensitive in determining the cause of H influenzae type B cellulitis.