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Acute otitis media (AOM) is commonly caused by bacterial pathobionts of the nasopharynx that ascend the Eustachian tube to cause disease in the middle ears. To model and study the various complexities of AOM, common human otopathogens are injected directly into the middle ear bullae of rodents or are delivered with viral co-infections which contribute to the access to the middle ears in complex and partially understood ways. Here, we present the novel observation that Bordetella bronchiseptica , a well-characterized respiratory commensal/pathogen of mice, also efficiently ascends their Eustachian tubes to colonize their middle ears, providing a flexible mouse model to study naturally occurring AOM. Mice lacking T and/or B cells failed to resolve infections, highlighting the cooperative role of both in clearing middle ear infection. Adoptively transferred antibodies provided complete protection to the lungs but only partially protected the middle ears, highlighting the differences between respiratory and otoimmunology. We present this as a novel experimental system that can capitalize on the strengths of the mouse model to dissect the molecular mechanisms involved in the generation and function of immunity within the middle ear., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2022 Dewan, Sedney, Caulfield, Su, Ma, Blas-Machado and Harvill.)

Mycoplasma bovis (M. bovis) is a common inhabitant of the upper and lower respiratory tracts of cattle and is considered to be the main aetiological agent of otitis media in calves. The eustachian tube appears to be the most common portal for pathogens to enter the middle ear. We investigated the transmission route of M. bovis causing otitis media that progressed to meningitis or meningoencephalitis in Japanese Black cattle. M. bovis was detected in 10 cases by a loop-mediated isothermal amplification method or by immunohistochemistry. One case of caseonecrotic granulomatous meningoencephalitis, one case of caseonecrotic granulomatous meningitis, one case of suppurative meningoencephalitis, eight cases of eustachitis, nine cases of tonsillitis and six cases of suppurative bronchopneumonia were identified by histopathological examination. M. bovis antigen was detected in the eustachian tubes of eight cases. In nine cases, M. bovis was also detected in tonsillar epithelial crypts and lumina, in intraluminal inflammatory cells and in the epithelial cells of minor salivary glands located around the eustachian tubes and tonsils. The results suggest that M. bovis can infect and colonize the tonsils and enter the eustachian tubes, causing otitis media, which, in cases of chronic infection, can progress to meningitis., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

Infection and inflammation of the middle ears that characterizes acute and chronic otitis media (OM), is a major reason for doctor visits and antibiotic prescription, particularly among children. Nasopharyngeal pathogens that are commonly associated with OM in humans do not naturally colonize the middle ears of rodents, and experimental models in most cases involve directly injecting large numbers of human pathogens into the middle ear bullae of rodents, where they induce a short-lived acute inflammation but fail to persist. Here we report that Bordetella pseudohinzii, a respiratory pathogen of mice, naturally, efficiently and rapidly ascends the eustachian tubes to colonize the middle ears, causing acute and chronic histopathological changes with progressive decrease in hearing acuity that closely mimics otitis media in humans. Laboratory mice experimentally inoculated intranasally with very low numbers of bacteria consistently have their middle ears colonized and subsequently transmit the bacterium to cage mates. Taking advantage of the specifically engineered and well characterized immune deficiencies available in mice we conducted experiments to uncover different roles of T and B cells in controlling bacterial numbers in the middle ear during chronic OM. The iconic mouse model provides significant advantages for elucidating aspects of host-pathogen interactions in otitis media that are currently not possible using other animal models. This natural model of otitis media permits the study of transmission between hosts, efficient early colonization of the respiratory tract, ascension of the eustachian tube, as well as colonization, pathogenesis and persistence in the middle ear. It also allows the combination of the powerful tools of mouse molecular immunology and bacterial genetics to determine the mechanistic basis for these important processes., Competing Interests: The authors have declared that no competing interests exist.

Tuberculosis involving mastoid and ear is an uncommon entity presenting with myriads of non-specific features and difficult to diagnose, being a paucibacillary condition. The involvement of otomastoid compartment is hypothesised to be of haematogenous origin. Rarely it can spread directly via tympanic membrane perforation or via reflux through eustachian tube. The usual picture of presentation tends to be one of indolent ear infection not responsive to usual antibiotic treatment and symptomatology being out of proportion to examination findings. We present a case of aural tuberculosis presenting with zygomatic and Bezold abscess without other symptoms, and the usefulness of GeneXpert test in mycobacterial detection in such paucibacillary conditions., Competing Interests: Competing interests: None declared., (© BMJ Publishing Group Ltd (unless otherwise stated in the text of the article) 2018. All rights reserved. No commercial use is permitted unless otherwise expressly granted.)

Background: Methicillin-resistant Staphylococcus aureus (MRSA) is recognized as a cause of nosocomial infections in both human and veterinary medicine. Studies that examine the nasopharynx and guttural pouches of the horse as carriage sites for MRSA have not been reported., Hypothesis/objective: MRSA colonizes the nasopharynx and guttural pouch of horses. To determine the prevalence of MRSA in equine nasopharyngeal wash (NPW) and guttural pouch lavage (GPL) samples in a field population of horses., Samples: One hundred seventy-eight samples (123 NPW and 55 GPL) from 108 horses., Methods: Prospective study. Samples were collected from a convenience population of clinically ill horses with suspected Streptococcus equi subsp. equi (S. equi) infection, horses convalescing from a known S. equi infection, and asymptomatic horses undergoing S. equi screening. Samples were submitted for S. aureus aerobic bacterial culture with mannitol salt broth and two selective agars (cefoxitin CHROMagar as the PBP2a inducer and mannitol salt agar with oxacillin). Biochemical identification of Staphylococcus species and pulsed-field gel electrophoresis (PFGE), to determine clonal relationships between isolates, were performed., Results: Methicillin-resistant Staphylococcus (MRS) was isolated from the nasopharynx of 7/108 (4%) horses. Three horses had MRSA (2.7%), and 4 had MR-Staphylococcus pseudintermedius (MRSP). MRSA was isolated from horses on the same farm. PFGE revealed the 3 MRSA as USA 500 strains., Conclusions and Clinical Importance: Sampling the nasopharynx and guttural pouch of community-based horses revealed a similarly low prevalence rate of MRSA as other studies sampling the nares of community-based horses. More study is required to determine the need for sampling multiple anatomic sites when screening horses for MRSA., (Copyright © 2017 The Authors. Journal of Veterinary Internal Medicine published by Wiley Periodicals, Inc. on behalf of the American College of Veterinary Internal Medicine.)

Background: Balloon Eustachian Tuboplasty (BET) is a new minimally invasive treatment for chronic Eustachian tube dysfunction (ETD). Initially, perioperative prophylactic antibiotic therapy with ciprofloxacin 2 × 500 mg p.o. for 5 days was administered. This study aimed to characterize the bacterial flora in the ET, nose, and pharynx in patients with chronic obstructive ETD. Additionally, we investigated the necessity of perioperative antibiotic prophylaxis in BET patients., Patients and Methods: We examined 40 patients undergoing BET: 20 patients with and 20 patients without perioperative antibiotic prophylaxis. All patients were followed-up for clinical signs and symptoms of local infection for at least 2 weeks after surgery. Following BET, the tips of 35 balloon catheters, as well as swabs from the nose and pharynx were sent for microbiologic analysis., Results: None of these 40 patients had postoperative signs of infection. Of the swabs of the balloon catheters, 46% were sterile and 23% showed standard flora. The remaining 31% of swaps revealed specific bacteria. However, none of the nasal or nasopharyngeal swaps were sterile., Conclusion: Due to the lack of signs of postoperative infection in either investigated group, the authors no longer favor use of perioperative antibiotic prophylaxis in patients undergoing BET. The relevance of biofilms and pathogen colonization to ET function has recently been intensively discussed, and should be further investigated in future studies.

Eustachian tube (ET) dysfunction may cause pathological changes in the middle ear, including recurrent acute otitis media and otitis media with effusion (OME). Mechanical obstruction of the ET may be caused by primary tumor-like lesions arising from ET or secondary ET infiltration due to nasopharyngeal and parapharyngeal space tumor. Tuberculosis is known to affect almost every organ in the body, and it should be a concern of each and every medical practitioner. However, tuberculosis of the ET has not been reported in the literature previously. This article reports primary tuberculosis arising in the ET that presented as aural fullness and hearing disturbance in a patient with OME., (Copyright © 2015 Elsevier Inc. All rights reserved.)

The most common disorders of the equine guttural pouches are empyema, tympany, mycosis, and temporohyoid osteoarthropathy. Diagnosis of these conditions is made primarily by imaging with endoscopy, radiographs, computed tomography, and/or MRI. Medical treatment with anti-inflammatories, antimicrobials, and/or antifungals may be successful in some cases, but many of these disorders necessitate surgical intervention. Direct surgical approaches to the guttural pouch are difficult because of their complex anatomy and relationship with important structures, thus precipitating a move toward minimally invasive procedures when possible., (Copyright © 2015 Elsevier Inc. All rights reserved.)

Objective: To review the potential contributory role of biofilms to post-tympanstomy tube otorrhea and plugging as well as the available interventions currently utilized to prevent biofilm formation on tympanostomy tubes., Data Sources: A literature review was performed utilizing the MEDLINE/Pubmed database from 1980 to 2013., Review Methods: Electronic database was searched with combinations of keywords "biofilm", "tympanostomy tube", "ventilation tube", and "post-tympanostomy tube otorrhea"., Results: Two of the most common sequelae that occur after tympanostomy tube insertion are otorrhea and tube occlusion. There is an increased evidence supporting a role for biofilms in the pathogenesis of otitis media. In this review, we have shown a multitude of novel approaches for prevention of biofilm associated sequelae of otitis media with effusion. These interventions include (i) changing the inherent composition of the tube itself, (ii) coating the tubes with antibiotics, polymers, plant extracts, or other biofilm-resistant materials, (iii) tubal impregnation with antimicrobial compounds, and (iv) surface alterations of the tube by ion-bombardment or surface ionization., Conclusion: Currently, there is not one type of tympanostomy tube in which bacteria will not adhere. The challenges of treating chronic post-tympanostomy tube otorrhea and tube occlusion indicate the need for further research in optimization of tympanostomy tube design in addition to development of novel therapies., (Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.)

There is considerable evidence that influenza A virus (IAV) promotes adherence, colonization, and superinfection by S. pneumoniae (Spn) and contributes to the pathogenesis of otitis media (OM). The complement system is a critical innate immune defense against both pathogens. To assess the role of the complement system in the host defense and the pathogenesis of acute pneumococcal OM following IAV infection, we employed a well-established transtympanically-induced mouse model of acute pneumococcal OM. We found that antecedent IAV infection enhanced the severity of acute pneumococcal OM. Mice deficient in complement C1qa (C1qa-/-) or factor B (Bf -/-) exhibited delayed viral and bacterial clearance from the middle ear and developed significant mucosal damage in the eustachian tube and middle ear. This indicates that both the classical and alternative complement pathways are critical for the oto-immune defense against acute pneumococcal OM following influenza infection. We also found that Spn increased complement activation following IAV infection. This was characterized by sustained increased levels of anaphylatoxins C3a and C5a in serum and middle ear lavage samples. In contrast, mice deficient in the complement C5a receptor (C5aR) demonstrated enhanced bacterial clearance and reduced severity of OM. Our data support the concept that C5a-C5aR interactions play a significant role in the pathogenesis of acute pneumococcal OM following IAV infection. It is possible that targeting the C5a-C5aR axis might prove useful in attenuating acute pneumococcal OM in patients with influenza infection.

Acute otitis media (AOM) is a polymicrobial disease, which usually occurs as a complication of viral upper respiratory tract infection (URI). While respiratory viruses alone may cause viral AOM, they increase the risk of bacterial middle ear infection and worsen clinical outcomes of bacterial AOM. URI viruses alter Eustachian tube (ET) function via decreased mucociliary action, altered mucus secretion and increased expression of inflammatory mediators among other mechanisms. Transient reduction in protective functions of the ET allows colonizing bacteria of the nasopharynx to ascend into the middle ear and cause AOM. Advances in research help us to better understand the host responses to viral URI, the mechanisms of viral-bacterial interactions in the nasopharynx and the development of AOM. In this review, we present current knowledge regarding viral-bacterial interactions in the pathogenesis and clinical course of AOM. We focus on the common respiratory viruses and their established role in AOM.

Because M. bovis otitis media is an economically important problem, there is a need to understand the pathogenesis of disease, not only to improve our understanding of the factors contributing to the development of this disease but also to inform the development of improved diagnostic tests and therapy. Oral ingestion of M. bovis-contaminated milk is linked, but not definitively proven, to development of otitis media. In the current study, we demonstrate that oral ingestion of M. bovis infected colostrum can result in an ascending infection and development of otitis media. Importantly, M. bovis was found to have a previously unrecognized tendency for colonization of the tonsils of calves, which most likely contributed to the subsequent development of otitis media. In contrast, transtracheal inoculation failed to produce clinically significant upper respiratory tract disease, although did induce lower respiratory tract disease. The upper respiratory tract was the major site of M. bovis-specific B cell and mucosal IgA responses in calves inoculated by the oral route. The oral inoculation route of infection presented here is particularly suited to the study of host-pathogen interactions during initial colonization of the tonsils, expansion of infection and dissemination to the lower respiratory tract and middle ear. In addition, it could be used to investigate potential new preventative or control strategies, especially those aimed at limiting colonization of the tonsils and/or spread to the middle ear.

Mycotic encephalitis caused severe ataxia and other neurologic deficits in a horse. The finding of a single, large focus of cerebral malacia, with histopathologic evidence of fungal elements, suggested infection was a result of direct transfer from the frontal sinuses, rather than hematogenous spread from the guttural pouch.

Background: Acute otitis media (AOM) is the most common childhood infection caused by bacteria. The pathogenesis of AOM implicates initial adherence of a pathogen to the nasopharyngeal epithelium, which is followed by bacterial colonization of the middle ear cavity through the Eustachian tube. N-acetylgalactosamine (GalNAc) is an important constituent of mucins and GalNAc containing sugar residues seem to be essential for initial adherence of respiratory bacteria to the surface of epithelial cells., Objective: To explore the localization of GalNAc residues, we incubated Eustachian tube sections from Streptococcus pneumoniae infected and normal control rats with seven biotinylated, GalNAc recognizing lectins: Bauhinia purpurea lectin (BPA), Psophocarpus tetragonolobus lectin (PTA), Helix aspersa lectin (HAA), Helix pomatia lectin (HPA), Phaseolus lunatus lectin (PLA), Sophora japonica lectin (SJA) and Vicia Villosa isolectin B4 (VVA-B4)., Results: The mucin producing epithelium and submucosal glands of the normal Eustachian tube contained GalNAc residues, as evidenced by binding of several of the lectins. Lectin binding specificity and intensity changed following acute middle ear infection. BPA was the only lectin that exclusively stained the surface epithelium and the serous acini of the submucosal glands in the infected animals, whereas no binding was detected in the normal controls. HPA, HAA, PTA and VVA-B4 binding to surface epithelial cells increased after infection, indicating an active secretion of GalNAc containing glycans. Quantitative analysis of submucosal gland staining intensity showed significantly more GalNAc residues in the normal Eustachian tube, compared to infected animals., Conclusion: We conclude that the mucous producing elements of the normal rat Eustachian tube contain GalNAc residues essential for respiratory pathogen adherence. In addition, the GalNAc residue specificity and reacting intensity change in relation to acute infection, which may be important in relation to subsequent development of secretory otitis media or formation of a bacterial biofilm in the middle ear. The results show that GalNAc residues increased in both the submucosal serous glands and in the surface epithelium of the Eustachian tube after middle ear infection with S. pneumoniae., (Copyright © 2011 Elsevier Ltd. All rights reserved.)

Adenoids and/or tonsil inflammation with concomitant obstructive hypertrophy is one of the oldest and most common pediatric problems. Adenoids are a component of Waldeyer's ring and because of their anatomic position can be relevant in the pathogenesis of otitis media when they are inflamed and/or enlarged. Adenoid pads can create mechanical eustachian tube obstruction. Therefore, in some cases, adenoidectomy may have a role in the clinical management of otitis media with effusion. However, eustachian tube dysfunction related to the adenoids may also have an allergy-related functional component. Allergic inflammation has been described for middle ear effusion, and some studies have reported that mast cells increase and allergic mediators release in adenoids as well. Nasal endoscopy has a key role in confirming a diagnosis of adenoid hypertrophy and/or adenoiditis and in detecting an association between adenoid inflammation/infection and otitis media with effusion, especially during infancy and early childhood.

Background: Lysozyme is an antimicrobial innate immune molecule degrading peptidoglycan of the bacterial cell wall. Lysozyme shows the ubiquitous expression in wide varieties of species and tissues including the tubotympanum of mammals. We aim to investigate the effects of lysozyme depletion on pneumococcal clearance from the middle ear cavity., Methods: Immunohistochemistry was performed to localize lysozyme in the Eustachian tube. Lysozyme expression was compared between the wild type and the lysozyme M-/- mice using real time quantitative RT-PCR and western blotting. Muramidase activity and bactericidal activity of lysozyme was measured using a lysoplate radial diffusion assay and a liquid broth assay, respectively. To determine if depletion of lysozyme M increases a susceptibility to pneumococal otitis media, 50 CFU of S. pneumoniae 6B were transtympanically inoculated to the middle ear and viable bacteria were counted at day 3 and 7 with clinical grading of middle ear inflammation., Results: Immunolabeling revealed that localization of lysozyme M and lysozyme P is specific to some/particular cell types of the Eustachian tube. Lysozyme P of lysozyme M-/- mice was mainly expressed in the submucosal gland but not in the tubal epithelium. Although lysozyme M-/- mice showed compensatory up-regulation of lysozyme P, lysozyme M depletion resulted in a decrease in both muramidase and antimicrobial activities. Deficiency in lysozyme M led to an increased susceptibility to middle ear infection with S. pneumoniae 6B and resulted in severe middle ear inflammation, compared to wild type mice., Conclusion: The results suggest that lysozyme M plays an important role in protecting the middle ear from invading pathogens, particularly in the early phase. We suggest a possibility of the exogenous lysozyme as an adjuvant therapeutic agent for otitis media, but further studies are necessary.

Conclusions: This is a suitable model for the study of different features of middle ear inflammation. This model allows manipulations inside the middle ear while preserving relevant structures such as the tympanic membrane, and provides a useful model for the study of interactions between bacterial infection and eustachian tube dysfunction., Objectives: Analysis of early and late histological features in an experimental model of Pseudomonas aeruginosa middle ear inoculation in the rat designed for the study of middle ear procedures., Materials and Methods: Thirty Wistar rats were inoculated with Pseudomonas aeruginosa in the tympanic bulla followed by the cauterization of the eustachian tube. Culturing of middle ear effusion was carried out at 7 days follow-up and at sacrifice. Processing of the temporal bones for light microscopy was performed at 7, 14, 30 and 60 days., Results: Early cultures were positive in most cases, thus proving that middle ear inflammation was due to the presence of inoculated Pseudomona aeruginosa. Mucoperiosteal inflammatory changes similar to those observed in human middle ear infection were seen. Acute inflammatory cell infiltration was seen at 7 and 14 days, gradually decreasing to chronic inflammatory changes with fibroplasia at 60 days. Bone resorption was observed at 7 and 14 days, changing to a bony deposition at 30 and 60 days.

Case Description: A 6-year-old Appaloosa mare was examined because of inappetance, difficulty eating, and swelling and mucopurulent discharge in the right eye., Clinical Findings: Results of a CBC and serum bio-chemical analysis revealed no important findings. Ophthalmologic examination revealed scarring and ulceration of the superficial layers of the cornea. Endoscopic examination of the upper portion of the respiratory tract and auditory tube diverticula (guttural pouches) revealed abnormal thickness of the right stylohyoid bone and a plaque suggestive of mycotic growth on the left internal carotid artery. Radiographic examination revealed right-sided otitis media. Temporohyoid osteoarthropathy in the right guttural pouch and mycosis in the left guttural pouch were diagnosed., Treatment and Outcome: Ceratohyoidectomy of the right stylohyoid bone was performed, and the left internal carotid artery was occluded via placement of stainless steel spring embolization coils. The mare regained the ability to eat without difficulty and improved clinically for approximately 4 weeks. However, the mare returned to the medical center 53 days after surgery with left-sided Horner syndrome, atrophy of the right side of the tongue, and a 3-week history of dysphagia and weight loss. Endoscopic evaluation revealed progression of mycotic growth in the left guttural pouch. The mare was euthanatized., Clinical Relevance: Although the mycotic lesion in the left guttural pouch was an incidental finding at the time of initial examination, the lesion progressed to cause dysphagia and Horner syndrome after occlusion of the left internal carotid artery, a treatment that is typically associated with resolution of guttural pouch mycosis. Arterial occlusion is not necessarily a reliable method of resolving guttural pouch mycosis.

This aetiological study of guttural pouch mycosis (GPM) in the horse was based on the retrospective study of 21 horses brought into the National Veterinary School of Lyon (France) between 1998 and 2002. Biopsies were taken from the lesions caused by GPM during endoscopic examination. In 87% of the cases, direct examination gave positive results, whereas 43% of the cultures were found to be negative. The main fungi observed were Aspergillus fumigatus (in three cases), A. versicolor (in two cases, together with other fungi), and A. nidulans and A. niger (one case each). In six cases, the Aspergillus species could not be identified. In two cases, cleistothecia and/or Hulle cells were observed. In three cases, fungi other than Aspergillus were seen, mixed or not with Aspergillus. These results underline the importance of Aspergillus fumigatus in the development of GPM in horses.

Objectives: To investigate the histomorphologic impact of acute otitis media on the subepithelial glands of the eustachian tube. Previous investigations have shown an increase of eustachian tube goblet cell density during and up to at least 6 months after acute otitis media., Study Design: Longitudinal study in an experimental animal model of acute otitis media caused by Streptococcus pneumoniae., Methods: Bacterial middle ear challenge, after which the animals were killed, in groups of five rats on Days 4, 8, 16, 90, and 180. Dissection and preparation of the eustachian tube and adjacent structures, followed by serial transverse sectioning, periodic acid-Schiff/alcian blue staining, and qualitative/quantitative morphometric light-microscopic investigations of the histomorphology of the eustachian tube glands, in particular, the stainability, composition, volume, and number of gland acini., Results: The volume of the eustachian tube glands progressed to peak 16 days after inoculation, followed by a gradual normalization. The volume was still increased 3 months after the acute infection but completely normalized after 6 months. The increase was primarily due to hypertrophy of the mucous gland components, as the serous gland component volume and number of gland acini was unchanged. The periodic acid-Schiff/alcian blue staining of the mucous gland acini changed temporarily during the acute infection, indicating changes in mucus glycoprotein composition, from neutral to acidic/sulfated., Conclusion: The volume of the eustachian tube glands increases during and up to at least 3 months after acute otitis media, primarily because of hypertrophy of the mucous gland components. This may compromise tubal ventilatory and drainage function.

Background: Prior investigations have shown that the number of mucus-producing goblet cells in the middle ear mucosa is highly increased during and up to at least 6 months after experimental acute otitis media. This may, in conjunction with deteriorated eustachian tube function, predispose to subsequent development of secretory otitis media. One reason for the deteriorated tubal function after acute otitis media has been suggested to be an excessive accumulation of mucus secretions, blocking the tube and thereby clearance of the middle ear. This investigation determines the density of the mucus-producing goblet cells in the eustachian tube during and up to 6 months after experimental acute otitis media., Methods: Middle ear inoculation of Streptococcus pneumoniae in 25 rats. Groups of five animals, killed on Days 4, 8, 16, 90, and 180. Dissection and decalcification of the eustachian tube, followed by paraffin embedding and serial transverse sectioning, periodic acid-Schiff/Alcian blue staining and morphometric determination of the goblet cell density in every 20th section, using a light microscope., Results: The goblet cell density was increased on Day 8 and later in the tympanic orificium, in addition to the tympanic and midportion third of the tube. Increased goblet cell density was seen in the pharyngeal third on Days 8 and 16, whereas no changes were registered in the pharyngeal orificium. Pathologic intraepithelial glands formed after the infection and goblet cells were found in mucosal areas normally devoid of these., Conclusions: The eustachian tube goblet cell density is increased during and up to 6 months after acute otitis media. Indicated excessive secretion of mucus by more goblet cells may contribute to the deteriorated eustachian tube function found after acute otitis media and thus predispose, sustain, or aggravate middle ear disease.

Objective: To describe the clinical and histopathologic progression of a rat model of otitis media with effusion caused by eustachian tube obstruction (ETO) with and without Streptococcus pneumoniae infection., Methods: In 164 rats, the left, bony eustachian tube was approached via a ventral incision and obstructed with dental material. Then 108 rats were infected via an intrabullar injection with S pneumoniae. At 48 hours, the infected rats were treated for 5 days with ampicillin. All ears were evaluated by weekly otomicroscopy. On each of days 1, 2, 7, 21, 35, 56, and 112, four rats were killed for histologic study. All effusions were cultured for bacteria., Results: Fourteen rats died of surgical complications; effusion resolved by 2 weeks in 9 rats. During the first few days, infected ears with ETO had bulging tympanic membranes, followed by tympanic membrane retraction, purulent effusion, and otorrhea (50%) over the next few weeks, whereas uninfected ears with ETO developed retraction and serous effusion during the same time frame. At later times, all ears with ETO presented with retraction and serous or serous-mucoid effusion. S pneumoniae was recovered only from the infected ears with ETO (days 1 and 2), with some colonization by nonpathogenic microorganisms observed equally in both groups of ears. Histology showed a typical acute inflammatory reaction in the challenged ears with ETO through day 14 and then a chronic inflammation for all ears with ETO., Conclusion: The experimental methods provoked reproducible pathologic signs similar to those for otitis media with effusion. Given the availability of rat-specific reagents, this model is well suited for studies of cytokine elaboration during disease pathogenesis.

Objective: To evaluate the cytological and microbiological contents of guttural pouch washes of ten randomly selected horses restrained so as to prevent them lowering their heads, and to assess the possible effects on the guttural pouch environment in these horses., Procedure: Cytological and microbiological studies were performed on guttural pouch washes of ten clinically normal horses restrained in a standing position so as to prevent them from lowering their heads below normal, as would happen during transportation on long journeys. They were restrained for 12 or 24 h and cytological, bacteriological and mycological findings in guttural pouch washes were recorded., Results: The cytological gradings and neutrophil concentrations of guttural pouch washings were higher in horses that had their heads restrained for a longer period. Washings from these horses were more likely to contain cultivable bacteria and were the only washes yielding potentially pathogenic bacterial species., Conclusion: Variation in the cytological differential counts and bacterial cultures of guttural pouch lavages may be found in clinically normal horses which have had their heads restrained in an elevated position for periods from 12 to 24 h. This should be considered when examining this site and care must be taken when interpreting cytology of guttural pouch lavages in samples taken after transportation for more than 12 h. Restriction of head movement could also affect the normal pouch enviroment and predispose it to disease.

Objective: To study the effect of various middle ear effusions on the structure of the lamina propria of the tympanic membrane., Methods: Sterile and infective middle ear effusions were induced by obstruction of the eustachian tube in specific pathogen-free (SPF) rats and in rats with upper airway infections (URI), respectively. The condition of the tympanic membrane was monitored at regular intervals. After varying survival times, the animals were killed and the tympanic membranes processed for light and electron microscopy., Results: Sterile effusions always resulted in tympanosclerotic lesions. These lesions did not develop in the presence of primary-infected effusions. These effusions had a severe destructive effect on the lamina propria, followed by fibrosis. Generally, secondary infection did not markedly affect preexisting tympanosclerotic lesions. Moreover, calcification disappeared when re-aeration of the middle ear occurred, but the abnormal collagen depositions persisted., Conclusions: Both sterile and infective effusions result in comprehensive irreversible changes in the lamina propria of the pars tensa. The development of tympanosclerosis is confined to sterile effusions. Mechanical injury and compromised vascularization of the lamina propria are likely to be important etiological factors in the development of tympanosclerosis.

The sterility of the eustachian tube and tympanic cavity of normal individuals is maintained not only by the adaptive immune system, but also by the mucociliary system and the antimicrobial molecules of innate immunity. Mucin production and periciliary fluid homeostasis are essential for normal mucociliary function and dysfunction of this system is an important risk factor for otitis media. The secreted antimicrobial molecules of the tubotympanum include lysozyme, lactoferrin, beta defensins, and the surfactant proteins A and D (SP-A, SP-D). Defects in the expression or regulation of these molecules may also be the major risk factor for otitis media.

Considerable evidence has implicated respiratory tract virus potentiation of bacterial adherence, colonization, and superinfection as a significant factor contributing to the pathogenesis of otitis media (OM). Influenza A and B viruses, adenovirus, and respiratory syncytial virus are the primary respiratory tract viruses associated with this disease. Investigations have established a dramatic increase in the development of experimental OM in chinchillas co-inoculated with influenza A virus and Streptococcus pneumoniae (Spn). The mechanism underlying this phenomenon was suggested to involve, in part, viral compromise of eustachian tube mucosal integrity and function. This study was designed to assess and compare the effect of adenovirus and influenza A virus infection on adherence, the kinetics of colonization, and invasion of the middle ear by Spn in the chinchilla model of OM. Cohorts were inoculated intranasally with adenovirus type 1 or influenza A virus, and then inoculated intranasally 7 days later with Spn 6A. All cohorts were observed over a 14-day period after challenge with Spn, and the incidence and severity of OM were assessed by several methods, including culture of the nasopharynx and middle ear effusions. The data indicated that influenza A virus promotes a significant increase in nasopharyngeal colonization by Spn, an increased incidence and severity of OM, and a sustained presence of Spn in the effusions. Adenovirus infection, however, did not enhance colonization by Spn or result in an increased incidence or severity of OM.

Objective: To identify features of guttural pouch (auditory tube diverticulum) empyema in horses and compare findings of uncomplicated guttural pouch empyema with guttural pouch empyema complicated by chondroids., Design: Retrospective study., Animals: 91 horses with guttural pouch empyema., Procedure: Medical records of horses with guttural pouch empyema were reviewed., Results: The most common owner complaint and abnormal finding was persistent nasal discharge. Chondroids were detected in 21% (19/91) of affected horses. Streptococcus equi was isolated from the guttural pouch in 14 of 44 horses; for Streptococcus spp, in vitro resistance to sulfadimethoxine and trimethoprim-sulfamethoxazole was detected. Retropharyngeal swelling and pharyngeal narrowing were significantly more prevalent in horses with chondroids, compared with horses with uncomplicated empyema. Ninety-three percent of affected horses were discharged from the hospital; at time of discharge, 66% had complete resolution of disease, 19% had improvement without resolution, and 15% did not have improvement., Conclusions and Clinical Relevance: Horses with persistent nasal discharge should be examined endoscopically for guttural pouch empyema. Treatment with lavage offers a good prognosis for resolution of uncomplicated guttural pouch empyema. Aggressive treatment with lavage and endoscopic snare removal of chondroids offers a good prognosis and may make surgical intervention unnecessary.

Percutaneous washes of the guttural pouches were obtained from two groups of 15 clinically normal horses, one lightly exercised and the other heavily exercised. Microbiological and cytological studies showed a wide variation in the differential cell counts. The cytological pattern of the normal lavages (< 5 per cent neutrophils) was characterised by a large proportion of ciliated columnar epithelial cells, a few non-ciliated cuboidal epithelial cells, and less than 1 per cent monocytes, lymphocytes, and eosinophils. Abnormal lavages (with more than 5 per cent neutrophils) had higher levels of bacterial growth than normal lavages. There were significant differences between the bacterial growth and total cell count, and also between the neutrophil contents of the lavages from the two groups of horses.

Occlusion of the internal carotid artery by insertion of intravascular platinum microcoils for guttural pouch mycosis was experimentally evaluated in 9 healthy adult Thoroughbred horses. The internal carotid artery was ligated to its origin, and an arteriotomy was made distal to the ligature, which was then occluded by insertion of the microcoil approximately 13 cm distal to its origin. Cessation of blood flow was determined visually and by angiography at the arteriotomy site. Six horses were evaluated for complication clinically and by endoscopy after surgery. One horse was necropsied after 30 days of surgery for histological evaluation of artery thrombus formation. In the other 3 horses, the blood flow of the right internal carotid artery was monitored, before and after microcoil occlusion of the left internal carotid artery. One or 2 microcoils stopped blood flow within a few minutes. No other abnormal findings were observed clinically. Thrombus was observed in the occluded segment of 1 horse 30 days after insertion; but no abnormalities were detected. The blood flow in the right internal carotid artery increased by approximately 28-58% after occlusion of the left internal carotid artery. This microcoil vascular occlusion technique causes an effective thrombosis, and based on experimental studies and clinical application in 2 horses with epistaxis due to guttural pouch mycosis, this technique would appear to be safe and efficacious.

The present study aimed to investigate the inhibitory activity of the normal epipharyngeal flora against the three most common acute otitis media (AOM) pathogens in healthy children, and to study if the inhibitory activity differs between alpha-hemolytic streptococci (AHS) sampled from the tubal orifice and from those sampled from the adenoid. A total number of ten isolates of AHS were collected from the tubal orifice and the adenoid, respectively, in ten children undergoing adenoidectomy or tonsillectomy. None of the children had a history of otitis media, neither secretory otitis media (SOM) nor AOM. The method used to test the bacterial interference in vitro was a modified agar overlay method. The results showed that the AHS from nasopharynx were able to inhibit the majority of the S. pneumoniae, nontypable Haemophilus influenzae and Moraxella catharralis isolates tested. The AHS isolates from the tubal orifice inhibited growth of 93% of S. pneumoniae, 79% of H. influenzae and 84% of M. catharralis isolates. The corresponding figures among isolates from the adenoid were 76, 48 and 62%. This difference in the inhibitory capacity between the AHS isolates collected from the adenoid, compared with the AHS collected from the tubal orifice, is statistically significant (P<0.01) and implies that it is important to know the exact sampling locality before conclusions are made concerning the significance of bacterial interference in the upper airways.

The pathogenesis of otitis media is a multifaceted process that is not completely understood. Eustachian tube dysfunction plays a central but uncertain role, as do viral and bacterial microorganisms. Of the latter, the three most important are Streptococcus pneumoniae, Haemophilus influenzae and Moraxella catarrhalis. This article reviews the various mechanisms of infection and the immune system's response to them.

The insertion of ventilation tubes to equalize pressure in the middle ear is the most common procedure used to treat otitis media. This article evaluates the advantages and drawbacks of ventilation and explores the various roles of the components of middle ear pressure, with special emphasis on oxygen-derived free radicals.

A 3-year-old Quarter Horse gelding was treated for left guttural pouch mycosis by ligation and balloon catheterization of the left internal carotid artery. Catheter advancement was shorter (10 cm) than the normally reported distance (13-15 cm), but was observed endoscopically during placement as it coursed within the internal carotid artery through the guttural pouch. The horse developed a persistently abnormal respiratory pattern after catheter placement, failed to gain consciousness, developed pulmonary edema, and died 5.5 hours postoperatively. Postmortem examination revealed an aberrant left internal carotid arterial course with location of the embolectomy catheter at the junction of the basilar and caudal cerebellar arteries. Brainstem neuronal necrosis and alveolar and interstitial pulmonary edema were identified on histological examination. Angiography may be used to identify aberrant branching patterns. Failure to identify and occlude aberrant branches may result in fatal epistaxis and Brainstem lesions.

Objective: To detect antibodies against Aspergillus fumigatus antigens in serum samples from horses and to evaluate the relevance of this method as an alternative approach to the diagnosis of mycosis of the auditory tube diverticulum (guttural pouch mycosis [GPM])., Animals: Twelve clinically normal horses (controls) and 12 horses with GPM diagnosed by endoscopic observation of characteristic mycotic plaques., Procedure: Antibodies to A fumigatus antigens were detected in serum by use of an ELISA and immunoblot analysis with extracellular antigens., Results: Antibodies against A fumigatus antigens were found in healthy and diseased horses. Titer of total Aspergillus antibodies was not diagnostic for GPM. In contrast, immunoblot analysis results indicated that 2 antigens of 22 and 26 kd were constantly recognized by sera from diseased horses., Conclusions: Reactivity to 22- and 26-kd A fumigatus antigens, as measured by immunoblot analysis, seemed to be diagnostic for GPM in horses.

A case is reported in a 9-year-old Anglo-Arab horse with guttural pouch mycosis caused by Emericella nidulans. Acute death occurred by exsanguination following erosion of the external carotid artery. Histopathological examination of the mycotic plaque demonstrated septate hyphae, conidial heads, hülle cells and mature cleistothecia containing characteristic ascospores. Specific identification was confirmed by culture. In accordance with previous reports, Emericella nidulans should be considered as the major agent of guttural pouch mycosis in Equidae.

To determine the kinetics of ascension of the eustachian tube (ET) by non-typeable Haemophilus influenzae (NTHi) in situ from the nasopharynx to the middle ear using an experimental model of otitis media (OM), we examined snap-frozen sections of chinchilla ET and middle ear mucosa for adherent bacteria over a 14 day time period. Via fluorescent- and transmission electron-microscopy, we found that NTHi preferentially adhered not to the epithelial cells but to the mucus in the ET and gradually ascended this tubal organ, reaching the middle ear approximately 10 days after intranasal inoculation of adenovirus-infected animals. The number of NTHi adherent to mucus at the pharyngeal portion of the ET increased significantly in the first 4 days after inoculation of the nares whereas the number of adherent bacteria in both the mid and tympanic portions of the ET increased more gradually over time. NTHi were not observed in the middle ear until approximately 7-10 days after inoculation of the nares which was coincident with the onset of clinical signs of OM. These data confirmed our earlier in vitro investigation which suggested that adherence to and growth within stagnant mucus within a ET compromised by adenovirus was a possible mechanism by which NTHi, resident in the nasopharynx, might gain access to the middle ear and induce OM.

Known numbers (CFU/ml) of middle ear pathogens (S. pneumoniae, H. influenzae, M. catarrhalis, S. aureus and beta-haemolytic streptococci group A) and non-pathogens (alpha-haemolytic S. mitis) were inoculated into one end of a micropipet containing a 35 mm long pillar of culture-negative middle ear effusion. The micropipets with the effusion/bacterial suspension were incubated at 37 degrees C and kept at various inclinations to the horizontal plane (15 degrees, 30 degrees and -75 degrees). All S. aureus, M. catarrhalis, alpha- and beta-haemolytic streptococci isolates examined survived in this medium for 18 h. The majority of alpha- and beta-haemolytic streptococci isolates penetrated the MEE, irrespective of the inclination of the micropipet, whereas the number of S. pneumoniae (p<0.01) and H. influenzae (p = NS) isolates penetrating the substrate increased when the micropipets were inclined at -75 degrees to the horizontal. None of the S. aureus and M. catarrhalis isolates penetrated the MEE pillar during the incubation. The present in vitro study demonstrated that MEE possesses an antibacterial property and is able to selectively hinder bacterial penetration.

Otitis media was introduced in chinchillas by direct transbullar inoculation with either viable or formalin-inactivated Moraxella (Branhamella) catarrhalis. Both groups of animals developed middle ear fluids (MEF) and severe inflammatory changes in the tubotympanum. Pure cultures of M. catarrhalis were recovered for up to 5 days after inoculation from those animals inoculated with viable bacteria. Significantly elevated anti-M. catarrhalis antibody titers were detected in post-inoculation sera and in MEF or bullar lavages, and an increased number of IgG-bearing cells was also observed in the tubotympanum of these animals. Control chinchillas inoculated with pyrogen-free sterile saline failed to show any signs of otitis media. Our data indicate that viable M. catarrhalis induce acute otitis media in the chinchilla but that the bacteria are rapidly eliminated from the middle ear, precluding its usefulness as a model to study acute otitis media. Moreover, the same concentration of nonviable organisms also induces severe inflammatory changes in the middle ear. These data indicate that the chinchilla may be a useful model for studying the role of nonviable M. catarrhalis or its cell wall components on the induction and persistence of inflammation in the middle ear.

The changes in the cell surface carbohydrates of the eustachian tube (ET) and middle ear subsequent to the intranasal (i.n.) inoculation of Streptococcus pneumoniae (Spn) type 6A were studied in the chinchilla model of otitis media (OM) using a lectin histochemical technique with six different lectins (SNA, WGA, Succ WGA, BSL II, PNA, ECL). The labeling pattern revealed not only the removal of the terminal sialic acid, but also exposure of N-acetylglucosamine (GlcNAc), a component of the trisaccharide receptor for Spn previously identified on human pharyngeal cells. The removal of sialic acid residues progressed from the nasopharyngeal to the tympanic orifice and was most pronounced in those animals from which Spn could be isolated from the middle ear. Our data indicate an alteration of the normal lectin labeling pattern and exposure of GlcNAc restricted mainly to the roof and neck portion, along the course of the eustachian tube. Exposure of part or all of a Spn adherence receptor structure by the pneumococcal enzymes, may facilitate colonization, invasion of the middle ear, and induction of OM.

Past studies showed that experimental rhinovirus colds in adults resulted in eustachian tube dysfunction and abnormal middle ear pressures. In the present study, the symptoms and pathophysiologic findings accompanying experimental influenza viral infection were documented. A total of 33 healthy adult volunteers were intranasally challenged with an influenza A/Kawasaki/86 (H1N1) virus and cloistered over a 9-day postchallenge period to monitor for evidence of infection, signs and symptoms of illness, and the extent and frequency of pathophysiologic responses of the nose, eustachian tube, and middle ear. Results showed a protective effect of high (> or = 16) prechallenge specific hemagglutination-inhibition antibody titer on the rate of infection and the magnitude and extent of provoked symptoms and pathophysiologic findings. Infected subjects with low (< 16) prechallenge serum antibody titers (n = 21) developed significant respiratory illness. These subjects also had objectively measurable increases in nasal secretion production, and decreased nasal patency and mucociliary clearance rates. More than 80% of the infected subjects developed eustachian tube dysfunction, and approximately 80% had middle ear underpressures of less than -100 mm H2O on study days 4 and 5. Five of 21 infected subjects with low prechallenge antibody titers had otoscopic evidence of otitis media with effusion. These results support a causal role for viral upper respiratory tract infection in the pathogenesis of otitis media, possibly mediated by the early development of eustachian tube dysfunction and abnormal middle ear pressure.

Previous studies have shown that influenza A virus inoculated via a transbullar approach can cause severe disorders of the chinchilla eustachian tube. In this study, we inoculated chinchillas both intranasally and transbullarly with influenza A virus (A/Alaska/6/77) to assess the effect of this virus on both the ciliary activity of eustachian tube epithelium and eustachian tube transport function. Data indicated that while the nature of the major lesions was indistinguishable, the differing routes of inoculation did influence the time course and initial location of virus-induced histopathology. Analysis of ciliary beat frequency and dye transport function indicated a maximal decrease approximately 7 to 14 days postinoculation, with return to normal function by 28 days postinoculation. Light and transmission electron microscopic observations of the evolution of histopathology and return to normal histology correlated well with functional assessment data.

Pathologic study of the ear was performed on 179 young swine, ranging in age from 1 day to 18.6 weeks. Histologically, eustachitis was the most common and its inflammatory reaction appeared to precede otitis. Immunohistochemically, Mycoplasma hyorhinis (Mhr) antigens were detected on the luminal surface of the auditory epithelia in 19 of 179 cases (10.6%). All the cases, positive for Mhr antigens, were associated with an acute eustachitis. Ultrastructural examination of two piglets confirmed these immunohistochemical data. The present results indicate that Mhr may be a primary cause of acute eustachitis in young swine.

Experimental otitis media induced in the chinchilla by inoculation of influenza A virus into the middle ear resulted in capillary engorgement, subepithelial hemorrhage, tissue edema and acute inflammatory cell infiltration. Quantitative morphometric measurements were made for 28 days. Ciliated cells appeared to be the primary target of this strain of influenza virus and demonstrated the greatest degree of damage. Three weeks were required to restore the ciliated epithelium in the tubotympanum to normal levels.

Streptococcus pneumoniae (Spn) are among the most frequently isolated pathogens in acute otitis media (AOM) and in otitis media with effusion (OME). Recently, the specific receptor for Spn has been identified as the trisaccharide unit Gal beta 1-4 GlcNAc beta 1-3 Gal beta with GlcNAc beta 1-3 Gal beta as the principal binding site. During the colonization of mucosal surfaces, pneumococci produce a variety of enzymes. This study was conducted to identify any resulting changes in the cell surface carbohydrate structure due to the action of these enzymes during pneumococcal otitis media (OM) in chinchillas. Using a lectin histochemical method with seven different lectins (SNA, LFA, WGA, Succ WGA, BSL II, PNA, ECL), the labeling pattern revealed not only the removal of the terminal sialic acid, but also the exposure of N-acetyl-glucosamine. These results suggested that Spn-produced enzymes uncover part of their own receptor structure and thus may facilitate adherence and subsequent infection.

The isolation and characterization of a mucoid, alginate-producing strain of Pseudomonas aeruginosa from a nonhuman host, namely, in chondroids from an equine guttural pouch, is reported for the first time. Pure cultures of P. aeruginosa 12534 were isolated from a 17-month-old pony mare with a history of chronic bilateral mucopurulent nasal discharge from the right guttural pouch. Transmission electron microscopy of chondroids showed mucoid P. aeruginosa growing as microcolonies within a matrix of extracellular material. On the basis of expression of the mucoid phenotype under different growth conditions, P. aeruginosa 12534 belongs to group 1 and resembles other isolates carrying the muc-23 mutation. The bulk of the extracellular material was characterized as being alginate by chemical and 1H nuclear magnetic resonance analyses, which showed that it had a composition similar to that produced by isolates of P. aeruginosa from human patients with cystic fibrosis.

Otitis media develops when certain bacterial pathogens gain access to the middle ear cavity from the nasopharynx through the eustachian tube. Adhesion of bacteria, in particular Streptococcus pneumoniae and Haemophilus influenzae, to the non-ciliated epithelial cells of the nasopharynx, close to the opening of the eustachian tube, is significantly correlated to the otitis-prone condition in children. Otitis-prone children have significantly fewer bacteria in the nasopharynx coated with the immunoglobulin secretory IgA (SigA) then healthy children have. Adhesion and occurrence of middle ear pathogens in the nasopharynx decreases with advancing age. Epstein-Barr virus, causative agent of infectious mononucleosis, causes a remarkable increase in bacterial adhesion to epithelial cells.