Related Experiment Video
Updated: Jun 22, 2026

Use of the EpiAirway Model for Characterizing Long-term Host-pathogen Interactions
Published on: September 2, 2011
Nontypeable Haemophilus influenzae isolated from intractable acute otitis media internalized into cultured human
Muneki Hotomi1, Jun Arai, Dewan S Billal
1Department of Otolaryngology-Head and Neck Surgery, Wakayama Medical University, 811-1 Kimiidera, Wakayama-shi, Wakayama, Japan.
Objectives:
The aim of this study is to examine the internalization of nontypeable Haemophilus influenzae (NTHi) into human epithelial cells.
Methods:
Bactericidal assay was applied to examine the effects of antibiotics against cell-adherent NTHi using HEp-2 cells. A trans-well chamber assay was applied to examine the internalization and penetration of NTHi using Detroit562 cells.
Results:
The adherence of NTHi to HEp-2 cells was noted after 2h of incubation. Azithromycin had a strong bactericidal effect against both cell-associated and non-adherent NTHi, while ceftriaxone did not show bactericidal effects on NTHi adhered to the HEp-2 cells. Three (60.0%) out of five NTHi isolates from the nasopharynx of children with intractable acute otitis media (AOM) internalized into and subsequently penetrated through the epithelial cells at various degrees. Azithromycin had a strong bactericidal effect against the cell-internalized NTHi, while ceftriaxone was bactericidal only against extracellular NTHi.
Conclusion:
The potential of NTHi as the intracellular pathogen may contribute to the persistent existence of this pathogen that result in the prolonged and intractable clinical course of AOM. Azithromycin may be a therapeutically significant antibiotic for patients with prolonged respiratory tract infections due to NTHi.
Related Concept Videos
Microbiota of the Respiratory Tract
Healthcare Associated Infections I: Iatrogenic, Exogenic and Endogenic
HAIs significantly increase the cost of health care. Extended stays in healthcare institutions, increased disability, increased costs of medications, including specialized antibiotics, and prolonged recovery times add to the patient's expenses and the healthcare institution and funding bodies. Common...
Atypical Pneumonia
Influenza

