To create an experimental model of Streptococcus pneumoniae type 3 meningogenic labyrinthitis (a leading cause of deafness) similar to that in human disease.
Cohort analytic study of guinea pigs that were inoculated intrathecally with varying dilutions of S pneumoniae type 3; the progress of the disease was compared with that in saline solution–inoculated control animals.
Healthy adult Hartley guinea pigs without clinical evidence of middle ear disease that were conveniently sampled.
Intrathecal inoculation of 104 to 106 colony-forming units of S pneumoniae type 3 into 13 guinea pigs; signs and symptoms of meningitis/labyrinthitis were observed for 15 days and compared with those in two saline solution–inoculated control animals.
Main Outcome Measures:
Morbidity—labyrinthitis, meningitis; end point—death.
The 104 to 106 colony-forming units of S pneumoniae type 3 caused inflammation that extended from the meninges to the inner ear via the cochlear aqueduct within 3 days after inoculation; a dose of 107 killed animals within 12 hours after inoculation. Three of five animals that were inoculated with a 106 dose died 3 days after inoculation; two of three animals that were inoculated with a 105 dose lived to 15 days after inoculation. One of two animals that were inoculated with a 104 dose did not become infected. Inflammation extended to the middle ear by round-window destruction. Reactive bone formation simulated labyrinthine osteosclerosis. Observers assessed histologic slides "blindly."
Guinea pigs can survive 15 days after intrathecal inoculation of a 105 dose, with morphologic features similar to those in human disease. This is an effective model for this study of meningogenic labyrinthitis.(Arch Otolaryngol Head Neck Surg. 1994;120:1342-1346)