Middle ear infections

Treatment of middle ear ventilation disorders: sheep as animal model for stenting the human Eustachian tube--a cadaver study

Eustachian tube disorders can lead to chronic otitis media with consecutive conductive hearing loss. To improve treatment and to develop new types of implants such as stents, an adequate experimental animal model is required. As the middle ear of sheep is known to be comparable to the human middle ear, the dimensions of the Eustachian tube in two strains of sheep were investigated. The Eustachian tube and middle ear of half heads of heathland and blackface sheep were filled with silicone rubber, blended with barium sulfate to induce X-ray visibility. Images were taken by digital volume tomography. The tubes were segmented, and a three-dimensional model of every Eustachian tube was generated. The lengths, diameters and shapes were determined. Additionally, the feasibility of endoscopic stent implantation and fixation was tested in cadaver experiments. The length of the tube between ostium pharyngeum and the isthmus and the diameters were comparable to published values for the human tube. The tube was easily accessible through the nose, and then stents could be implanted and fixed at the isthmus. The sheep appears to be a promising model for testing new stent treatments for middle ear ventilation disorders.

Otitis media among high-risk populations: can probiotics inhibit Streptococcus pneumoniae colonisation and the risk of disease?

Otitis media is the second most common infection in children and the leading cause for seeking medical advice. Indigenous populations such as the Inuits, indigenous Australians and American Indians have a very high prevalence of otitis media and are considered to be high-risk populations. Streptococcus pneumoniae, one of the three main bacterial causes of otitis media, colonises the nasopharynx prior to disease development. In high-risk populations, early acquisition of high bacterial loads increases the prevalence of otitis media. In these settings, current treatment strategies are insufficient. Vaccination is effective against invasive pneumococcal infection but has a limited impact on otitis media. Decreasing the bacterial loads of otitis media pathogens and/or colonising the nasopharynx with beneficial bacteria may reduce the prevalence of otitis media. Probiotics are live microorganisms that offer health benefits by modulating the microbial community and enhancing host immunity. The available data suggest that probiotics may be beneficial in otitis media. This review discusses the potential use of probiotics to reduce pathogen colonisation and decrease the prevalence of otitis media, providing justification for further investigation.

Characterization of Alloiococcus otitidis strains isolated from children with otitis media with effusion by Pulsed-Field Gel Electrophoresis

OBJECTIVE

Alloiococcus otitidis is a slow growing organism which has been isolated in a few studies on patients with otitis media with effusion (OME). According to the literature review, there is no study about the molecular typing of A. otitidis. In this study, the characteristics of A. otitidis isolates from patients with OME were investigated via Pulsed-Field Gel Electrophoresis (PFGE) typing method.

METHODS

A total of 50 children with OME, who underwent myringotomy or who had an insertion of a ventilation tube, were included in this study. The isolates were identified to the species level as A. otitidis using standard biochemical methods, following which the amplification and sequencing of the 16S rRNA gene were carried out. The molecular characteristic of A. otitidis was investigated by PFGE technique.

RESULTS

Fifteen isolates of A. otitidis were identified in the middle ear fluid of the patients. All the isolates were susceptible to ampicillin, amoxicillin/clavulanate and fluoroquinolones. All of the 15 isolates were typed by PFGE method and were found to include 13 different PFGE types.

CONCLUSION

The current study, being the first reports on the molecular typing of A. otitidis by PFGE method, shows that A. otitidis is a heterogenic organism in Iranian children who have OME.

Role of c-Jun N-terminal protein kinase 1/2 (JNK1/2) in macrophage-mediated MMP-9 production in response to Moraxella catarrhalis lipooligosaccharide (LOS)

Moraxella catarrhalis is a Gram negative bacterium and a leading causative agent of otitis media (OM) in children. Recent reports have provided strong evidence for the presence of high levels of matrix metalloproteinase (MMPs) in effusion fluids from children suffering with OM, however, the precise mechanisms by which MMPs are generated are currently unknown. We hypothesized that MMPs are secreted from macrophages in the presence of M. catarrhalis lipooligosaccharide (LOS). In this report, we demonstrate that in vitro stimulation of murine macrophage RAW 264.7 cells with LOS leads to secretion of MMP-9 as determined by ELISA and zymogram assays. We have also shown that inhibition of ERK1/2 and p38 kinase completely blocked LOS induced MMP-9 production. In contrast, inhibition of JNK1/2 by the specific inhibitor SP600125 actually increased the level of expression and production of MMP-9 at both mRNA and protein levels, respectively by almost five fold. This latter result was confirmed by knocking down JNK1/2 using siRNA. Similar results have been observed in murine bone marrow derived macrophages in vitro. In contrast to and in parallel with the LOS-induced increased levels of MMP-9 in the presence of SP600125, we found a corresponding dose-dependent inhibition of TIMP-1 (tissue inhibitor of matrix metalloproteinase-1) secretion. Results of subsequent in vitro studies provided evidence that when JNK1/2 was inhibited prior to stimulation with LOS, it significantly increased both the extent of macrophage cell migration and invasion compared to control cells or cells treated with LOS alone. The results of these studies contribute to an increased understanding of the underlying pathophysiology of OM with effusion in children.

Sh3pxd2b mice are a model for craniofacial dysmorphology and otitis media

Craniofacial defects that occur through gene mutation during development increase vulnerability to eustachian tube dysfunction. These defects can lead to an increased incidence of otitis media. We examined the effects of a mutation in the Sh3pxd2b gene (Sh3pxd2b^nee) on the progression of otitis media and hearing impairment at various developmental stages. We found that all mice that had the Sh3pxd2b^nee mutation went on to develop craniofacial dysmorphologies and subsequently otitis media, by as early as 11 days of age. We found noteworthy changes in cilia and goblet cells of the middle ear mucosa in Sh3pxd2b^nee mutant mice using scanning electronic microscopy. By measuring craniofacial dimensions, we determined for the first time in an animal model that this mouse has altered eustachian tube morphology consistent with a more horizontal position of the eustachian tube. All mutants were found to have hearing impairment. Expression of TNF-α and TLR2, which correlates with inflammation in otitis media, was up-regulated in the ears of mutant mice when examined by immunohistochemistry and semi-quantitative RT-PCR. The mouse model with a mutation in the Sh3pxd2b gene (Sh3pxd2b^nee) mirrors craniofacial dysmorphology and otitis media in humans.