Outer membrane protein profiles of paired nasopharyngeal and middle ear isolates of nontypable Haemophilus influenzae from Mexican children with acute otitis media.

We studied nontypable Haemophilus influenzae (NTHi) isolates from simultaneous cultures of nasopharyngeal exudates (NEs) and middle ear fluids (MEFs) obtained by tympanocentesis from 57 children with acute otitis media (AOM). Preparations of outer membrane proteins (OMPs) from 14 pairs of NTHi strains recovered from NEs and MEFs from 10 children with unilateral AOM and four with bilateral AOM were subjected to sodium dodecyl sulfate polyacrylamide gel electrophoresis. The NTHi subtypes were determined by comparing the OMP profiles of the isolated strains with those of eight reference NTHi subtypes. Of the 14 pairs, 10 (71%) were identical, and one (8%) was different; three strains isolated from NEs (21%) did not correspond to any of the reference subtypes (nonsubtypable). Subtypes 4, 6, 5, 3, and 8 were isolated in the present study, thereby showing that their distribution is similar to that of subtypes isolated from children with AOM in the United States and suggesting that common otogenic strains are widely distributed in North America.