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A mouse model for acute otitis media
1Department of Medical Microbiology, Lund University, Malmö University Hospital, Malmö, Sweden. asa.melhus@mikrobiol.mas.lu.se
Abstract:
To induce acute otitis media in the mouse and to describe the clinical and bacteriological course of the infection, middle ears of BALB/c, Swiss-Webster and C57BL/6 mice were inoculated with Streptococcus pneumoniae, Haemophilus influenzae and Moraxella catarrhalis. Systemic and local changes were monitored by clinical observations, otomicroscopy, and analysis of bacterial samples from blood and middle ears. Agglutination of mouse erythrocytes by M. catarrhalis was also tested. Depending on bacterial strain, bacterial dose, and mouse strain three responses were identified: acute otitis media, otitis media with serous effusion, or no reaction. BALB/c mice were the most susceptible animals. On day 3, 76% of the BALB/c mice had developed middle ear infection, 50% had a positive middle ear culture, 56% were bacteremic, and 10% had succumbed to a disseminated infection. The local infections lasted approximately a week. Animals which survived recovered without permanent deterioration or otomicroscopically discernible changes. In no case did M. catarrhalis induce a culture-positive middle ear infection, possibly due to an inability to agglutinate the mouse erythrocytes. The mouse model can become a useful tool in studies of pneumococcal and H. influenzae-induced otitis media, but the bacterial dose has to be carefully titrated and adjusted to the chosen mouse strain.
Insights
This study developed a mouse model for acute otitis media using Streptococcus pneumoniae and Haemophilus influenzae. BALB/c mice were most susceptible, showing high infection rates and susceptibility to disseminated disease.
Area of Science:
- Microbiology
- Infectious Diseases
- Otolaryngology
Background:
- Acute otitis media (AOM) is a common childhood illness.
- Bacterial pathogens like Streptococcus pneumoniae and Haemophilus influenzae are primary causes of AOM.
- Developing reliable animal models is crucial for understanding AOM pathogenesis and testing therapeutics.
Purpose of the Study:
- To establish and characterize a mouse model for acute otitis media.
- To investigate the clinical and bacteriological progression of middle ear infections induced by common otitis media pathogens.
- To evaluate the susceptibility of different mouse strains to these infections.
Main Methods:
- Inoculation of middle ears in BALB/c, Swiss-Webster, and C57BL/6 mice with Streptococcus pneumoniae, Haemophilus influenzae, and Moraxella catarrhalis.
- Monitoring of clinical signs, otomicroscopic changes, and bacterial presence in blood and middle ear samples.
- Assessment of Moraxella catarrhalis erythrocyte agglutination activity.
Main Results:
- Variable responses observed, including AOM, otitis media with effusion, or no infection, dependent on bacterial strain, dose, and mouse strain.
- BALB/c mice exhibited the highest susceptibility, with significant rates of middle ear infection, bacteremia, and disseminated infection.
- Moraxella catarrhalis did not establish culture-positive middle ear infections, potentially due to lack of erythrocyte agglutination.
- Infections resolved within approximately one week in surviving animals with no lasting pathological changes.
Conclusions:
- The developed mouse model is a valuable tool for studying Streptococcus pneumoniae and Haemophilus influenzae-induced otitis media.
- Careful titration of bacterial dose and selection of appropriate mouse strain are critical for model efficacy.
- Further research is needed to understand the role of Moraxella catarrhalis in otitis media pathogenesis using this model.
