Outer membrane protein and biotype analysis of pathogenic nontypable Haemophilus influenzae

Abstract

The techniques of biotype determination and sodium dodecyl sulfate-polyacrylamide gel electrophoresis of outer membrane protein preparations were applied to 35 epidemiology unrelated isolates of pathogenic nontypable H. influenzae. Three of 5 isolates obtained from the blood of unrelated newborns with sepsis had concordant major outer membrane protein profiles and were biotype IV. Two of 5 isolates obtained from the blood of unrelated older children or adults with bacteremia had concordant major outer membrane protein profiles, distinct from the common profile of neonatal strains, and were biotype II. The outer membrane protein profiles of the remaining 5 isolates from blood, 2 isolates from CSF and 23 isolates from middle ear aspirates of children with otitis media were unique, although each isolate had peptides with apparent MW of 16,000 and 31,500. Evidently, a subset of nontypable isolates associated with bacteremia has distinctive strain markers. Their pathogenicity may relate to a predilection for colonizing the female genital tract in the case of the common neonatal strain or an increased ability to evade host defenses.