Lipopolysaccharide gel profiles of Haemophilus influenzae type b are not stable epidemiologic markers.

Sodium dodecyl sulfate-polyacrylamide gel electrophoresis of lipopolysaccharide (LPS) was performed to assess the usefulness of this technique for the epidemiologic analysis of Haemophilus influenzae type b isolates. LPS samples were prepared from isolates which had been passaged either in vitro or in infant rats. Preparations from paired isolates from a number of epidemiologically related clinical situations also were examined. The gel patterns of LPS prepared on different occasions from an individual isolate were stable. However, the LPS gel patterns changed in 5 of 14 (36%) of the passaged isolates, and differences in gel patterns also were observed among epidemiologically related isolates. The variability in LPS electrophoretic patterns of individual isolates indicated that this technique is not useful for the epidemiologic analysis of H. influenzae type b disease.