Bactericidal effect of tosufloxacin on Haemophilus influenzae internalized in cultured human cells.

Nontypeable Haemophilus influenzae, one of the major causative bacteria for acute otitis media (AOM), is also considered to cause intractable otitis media including prolonged AOM and recurrent AOM in children by the mechanism of internalization of the bacteria into epithelial cells of middle ear mucosa. In this study, we visualized the dynamics of H. infiuenzae internalization in cultured human cells. We also examined the effects of antimicrobials, including a novel quinolone, tosufloxacin, and a cephem antibacterial agent, cefditoren, on H. influenzae internalized in cultured human cells. The results indicated that (1) H. infiuenzae were internalized into human cells, (2) cefditoren has no effect on internalized H. influenzae, and (3) tosufloxacin has a bactericidal action on H. infiuenzae invading human cells. These data strongly support high clinical efficacy of tosuffoxacin on intractable otitis media in children.