Acute otitis media develops in the rat after intranasal challenge of Streptococcus pneumoniae.
OBJECTIVE
The rat is a frequently used animal model for middle ear research. To date, acute otitis media (AOM) has been evoked after instillation of bacteria directly into the middle ear cavity or after traumatizing the tympanic membrane. The purpose of the study was to examine whether, with an intact tympanic membrane and middle ear cavity, intranasally deposited bacteria cause AOM and how tympanic membrane stimulation influences this procedure.


METHODS
In vivo, murine model.


METHODS
In a rat model, Streptococcus pneumoniae, type 3, was intranasally inoculated for 5 consecutive days. The tympanic membrane was treated with saline or with compound 48/80 or was left untreated. The development of AOM was evaluated by otomicroscopy, light microscopy, and middle ear culture.


RESULTS
Ninety percent of the ears developed AOM. However, when the tympanic membranes were treated with saline or compound 48/80, only 40% and 57%, respectively, developed AOM. In all, 23 of 40 ears developed AOM and 20 ears showed growth of bacteria.


CONCLUSIONS
Repeated intranasal deposition of S. pneumoniae, type 3, causes AOM in the rat. The development of AOM can be influenced by tympanic membrane stimulation.
Eriksson
Per Olof
PO
Department of Clinical Sciences, Otorhinolaryngology, Umeå University Hospital, Sweden. Per-Olof.Eriksson@ent.umu.se
Hellström
Sten
S
D000208:Acute Disease; D000818:Animals; D008297:Male; D009305:Nasopharynx / Q000382:microbiology*; D010033:Otitis Media / Q000382:microbiology*; D011008:Pneumococcal Infections / Q000382:microbiology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D013296:Streptococcus pneumoniae / Q000254:growth & development*; D013997:Time Factors; D014432:Tympanic Membrane / Q000382:microbiology / Q000473:pathology