Abstract
Strains of Haemophilus influenzae isolated from children in South Australia and the Northern Territory with systemic infections (mostly meningitis or epiglottitis) were subjected to serotyping, biotyping, outer-membrane protein (OMP) analysis and immunoblot subtyping. All 65 isolates examined were from blood or cerebrospinal fluid; 59 (91%) of the strains were identified as type b and the remainder as either type a (two strains) or non-typable (four strains). Of the 59 type b strains, 45 (76%) belonged to a single OMP subtype (equivalent to subtype 3L in the Barenkamp scheme); the remaining type b strains belonged to five other OMP subtypes. No correlation was apparent between OMP subtype and geographical region, clinical diagnosis or antimicrobial drug susceptibility pattern. Immunoblot subtyping enabled nine (18%) of 41 strains belonging to the principal OMP subtype to be distinguished from the remainder.