Distribution and relationship to serotype of Haemophilus influenzae biotypes isolated from upper respiratory tracts of children and adults in Papua New Guinea.

The relationship between serotypes and biotypes of 505 carriage strains of Haemophilus influenzae isolated from the upper respiratory tracts of well children, children with pneumonia, and healthy adults was studied. All except serotype c were significantly associated with one or two specific biotypes (P less than 0.001). No encapsulated organisms belonging to biotypes V, VI, or VII were encountered. No significant difference in the interaction of biotypes and serotypes isolated from well and sick children was present. Both encapsulated and nonserotypable biotype I H. influenzae strains were commonly carried in the upper respiratory tracts of healthy Melanesian children. The distribution of nonserotypable H. influenzae strains occurred throughout all biotypes, and the frequency of nonencapsulated biotype III and IV strains differed significantly from serotypable organisms with the same biotype (P less than 0.001).