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Acute otitis media develops in the rat after intranasal challenge of Streptococcus pneumoniae.
Umeå University, Faculty of Medicine, Clinical Sciences, Otorhinolaryngology.
Umeå University, Faculty of Medicine, Clinical Sciences, Otorhinolaryngology.
2003 (English)In: The Laryngoscope, ISSN 0023-852X, E-ISSN 1531-4995, Vol. 113, no 11, 2047-2051 p.Article in journal (Refereed) Published
Abstract [en]

OBJECTIVES/HYPOTHESIS: 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. STUDY DESIGN: 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. CONCLUSION: Repeated intranasal deposition of S. pneumoniae, type 3, causes AOM in the rat. The development of AOM can be influenced by tympanic membrane stimulation.

Place, publisher, year, edition, pages
2003. Vol. 113, no 11, 2047-2051 p.
National Category
Medical and Health Sciences
Identifiers
URN: urn:nbn:se:umu:diva-3351PubMedID: 14603072OAI: oai:DiVA.org:umu-3351DiVA: diva2:142013
Available from: 2004-01-19 Created: 2004-01-19 Last updated: 2010-04-12Bibliographically approved
In thesis
1. Developing otitis media: experimental studies in particular regarding inflammatory changes in the tympanic membrane
Open this publication in new window or tab >>Developing otitis media: experimental studies in particular regarding inflammatory changes in the tympanic membrane
2004 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Otitis media (OM), one of the commonest of childhood diseases, causes much suffering. OM exists in a variety of forms, two of which are acute otitis media (AOM) and otitis media with effusion (OME). The clinical courses of these conditions differ, AOM usually presenting with earache, fever and/or aural discharge, and the OME usually with hearing impairment. The tympanic membrane (TM) mirrors the events in the middle ear cavity, and pars flaccida (PF) is the initial site of inflammatory changes in the TM. PF is rich in mast cells (MCs), which by releasing various mediators, may trigger TM inflammation.

The aims of the present studies were to investigate early inflammatory changes in the TM in rat models of OM; after mast cell degranulation, in response to AOM, and OME, after myringotomy in AOM and in normal ears. Furthermore, we developed a new rat AOM model, that excludes surgical trauma and resembles the natural route of infection in man.

AOM and OME elicited the first inflammatory response in PF of the TM. The response to OME was discrete, but a slight increase in macrophages was found. During the first 48 hours of AOM, the inflammatory response was intense, following a bimodal pattern. This reaction is similar to that found after MC degranulation. In AOM, macrophages were the predominant cell in PF, while in pars tensa (PT), polymorphonuclear cells (mainly neutrophils) predominated.

When myringotomy was performed in AOM ears, the healing time was shorter than that of myringotomy in normal ears. The highly inflamed lamina propria seemed to promote healing.

During early AOM, as well as following myringotomy, fibrin extravasates into PF and PT. This fibrin deposition may be involved in regulating the inflammatory response.

Repeated nasal challenge with the otitis media pathogen Streptococcus pneumoniae provoked AOM and concomitant TM stimulation reduced the number of AOM cases. This new rat AOM model has the advantage of avoiding trauma in the middle ear cavity, while eliciting an intense inflammatory response in the middle ear cavity (MEC).

Publisher
56 p.
Series
Umeå University medical dissertations, ISSN 0346-6612 ; 871
Keyword
Otorhinolaryngology, otitis media with effusion, acute otitis media, myringotomy, tympanic membrane, rat, Streptococcus pneumoniae, compound 48/80, mast cell, Otorhinolaryngologi
National Category
Otorhinolaryngology
Research subject
Oto-Rhino-Laryngology
Identifiers
urn:nbn:se:umu:diva-180 (URN)91-7305-580-8 (ISBN)
Public defence
2004-02-13, Sal D (grå salen), 1D, Tandläkarhögskolan, Norrlands Universitetssjukhus, Umeå, 09:00 (English)
Opponent
Supervisors
Available from: 2004-01-19 Created: 2004-01-19 Last updated: 2010-04-12Bibliographically approved

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