Pathogenesis Of Acute Otitis Media Research Articles

Influenza A Virus-Induced Acute Otitis Media

To better understand the significance of viral upper respiratory tract infections in the pathogenesis of acute otitis media (OM), 27 adults underwent intranasal inoculation with influenza A virus. Monitoring consisted of antibody titer determination, tympanometry, and otoscopy. Microbiologic analysis consisted of cultures and polymerase chain reaction (PCR)-based detection for influenza A virus, Streptococcus pneumoniae, Haemophilus influenzae, and Moraxella catarrhalis. All subjects became infected with the challenge virus. By day 4, 16 (59%) developed middle ear pressures of -100 mm H2O or below and 4 (25%) of them developed OM. One subject (4%) developed purulent OM requiring myringotomy for pain relief. Middle ear effusion cultures were negative. PCR analysis of that subject's middle ear effusion and nasal washes were positive for influenza A virus and S. pneumoniae. These findings support a causal role for viral upper respiratory tract infections in the pathogenesis of OM, possibly mediated by middle ear underpressures and viral and bacterial middle ear infection.

Tobacco Smoke and Otitis Media in the Chinchilla Model

To determine whether tobacco smoke contributes to the pathogenesis of acute otitis media, chinchillas were exposed to mainstream tobacco smoke or sham conditions (cigarettes not lit) in a Walton smoke exposure machine for 20-minute cycles two or three times daily. After 6 to 8 weeks of daily exposure, 12 chinchillas were nasally injected with Streptococcus pneumoniae, and 18 chinchillas were injected into both middle ears with nontypable Haemophilus influenzae. Smoke or sham exposures were continued for 2 to 4 weeks after injection. Otitis media developed in none of the 12 nasally injected chinchillas and in all 18 chinchillas whose middle ears were injected with nontypable Haemophilus influenzae. Persistence of middle ear effusion and persistence of nontypable Haemophilus influenzae in the middle ear effusion were not different between the smoke- and sham-exposed groups. This suggests that mainstream smoke exposure does not change the natural course of otitis media in the chinchilla model.

Effect of tympanostomy tubes on the pathogenesis of acute otitis media

Intubation of the tympanic membrane as a treatment for acute otitis media is extremely controversial. This study was designed to determine the effect of tympanic membrane intubation in an experimental model for acute purulent otitis media. The right tympanic membrane of the chinchilla was intubated with Paparella Type I tympanostomy tubes. This procedure was followed in seven days by nasopharyngeal inoculation of Streptococcus pneumoniae and in an additional three days by nasopharyngeal inoculation of influenza A virus. Nasopharyngeal inoculation with these microorganisms results in acute purulent otitis media in 70 per cent of animals. The presence of the tympanostomy tubes did not reduce the incidence of clinical otitis media, nor did it reduce the pathologic changes within the middle ear space. The tympanostomy tubes did, however, significantly reduce the incidence and severity of pathologic changes in the subepithelial space of the middle ear mucosa.

Anaerobic Bacteria in Acute Otitis Media

Myringotomy with aerobic and anaerobic culture of middle ear fluid was performed on 28 infants with acute otitis media. Providine iodine solution was used to promote antisepsis of the external auditory canal prior to incision of the drumhead. Aerobic bacteria alone. predominantly Streptococcus pneumoniae and Haemophilus influenzae were isolated from 20 children (71 r/c). Cultures from two children yielded mixtures of aerobes and anaerobes and the middle ear culture from one child grew anaerobic clostridial species mixed with a few colonies of S. epidermidis. the isolation of anaerobic bacteria from the middle ear after attempting antisepsis of the external auditory canal suggests that these bacteria may occasionally play a direct or ancillary role in the pathogenesis of acute otitis media in infants and young children.

Experimental otitis media after nasal inoculation of Streptococcus pneumoniae and influenza A virus in chinchillas.

Otitis media developed in 67% of chinchillas inoculated intranasally with type 7 Streptococcus pneumoniae and influenza A virus. Only 4% of chinchillas inoculated with influenza alone and 21% of chinchillas inoculated with S. pneumoniae alone developed otitis media. Among the chinchillas that developed otitis media after inoculation with both pneumococcus and influenza, 73% of the affected ears contained effusion, and 27% of the affected ears showed tympanic membrane inflammation without middle ear effusion obtained on paracentesis. Although a majority of the ears with effusion yielded S. pneumoniae on culture, one-third of the effusions were sterile for aerobic bacteria. This model resembles conditions accompanying otitis media in humans and suggests that respiratory viral infection contributes significantly to the pathogenesis of acute otitis media.