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

Area of Science:

• Microbiology
• Infectious Diseases
• Otolaryngology

Background:

• Nontypeable Haemophilus influenzae is a primary cause of acute otitis media (AOM) in children.
• Bacterial internalization into middle ear mucosa epithelial cells contributes to intractable otitis media, including prolonged and recurrent forms.
• Understanding bacterial invasion dynamics is crucial for developing effective treatments.

Purpose of the Study:

• To visualize the dynamic process of Nontypeable Haemophilus influenzae internalization into cultured human cells.
• To evaluate the efficacy of specific antimicrobials, tosufloxacin and cefditoren, against internalized H. influenzae.
• To provide evidence supporting the clinical utility of tosufloxacin for intractable otitis media.

Main Methods:

• Utilized cultured human cells to visualize the internalization dynamics of H. influenzae.
• Applied antimicrobial agents, tosufloxacin (a novel quinolone) and cefditoren (a cephem), to infected cell cultures.
• Assessed the bactericidal effects of the tested antimicrobials on internalized H. influenzae.

Main Results:

• Confirmed the internalization of Nontypeable Haemophilus influenzae into human epithelial cells.
• Demonstrated that cefditoren lacks efficacy against H. influenzae once internalized within host cells.
• Showed that tosufloxacin exhibits a significant bactericidal effect on H. influenzae that have invaded human cells.

Conclusions:

• Tosufloxacin effectively targets and eliminates internalized Nontypeable Haemophilus influenzae within host cells.
• Cefditoren is ineffective against intracellular H. influenzae.
• The findings strongly support the potential high clinical efficacy of tosufloxacin in treating intractable otitis media in children.