Mycoplasma bovis May Travel Along the Eustachian Tube to Cause Meningitis in Japanese Black Cattle.

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.

Probing Immune-Mediated Clearance of Acute Middle Ear Infection in Mice.

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.

A model of chronic, transmissible Otitis Media in mice.

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.

Atypical presentation of aural tuberculosis with complication.

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.

Prevalence of Methicillin-Resistant Staphylococcus aureus from Equine Nasopharyngeal and Guttural Pouch Wash Samples.

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.

[Bacteriologic investigation of the Eustachian tube and the implications of perioperative antibiotics before balloon dilation]. / Bakteriologische Untersuchungen der Tuba auditiva und die Implikation einer perioperativen Antibiotikagabe vor Ballondilatation.

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.

Primary tuberculosis of the eustachian tube causing otitis media with effusion.

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.

Update on disorders and treatment of the guttural pouch.

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.

Strategies to prevent biofilm-based tympanostomy tube infections.

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.

Deletion of the complement C5a receptor alleviates the severity of acute pneumococcal otitis media following influenza A virus infection in mice.

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.

Oral inoculation of young dairy calves with Mycoplasma bovis results in colonization of tonsils, development of otitis media and local immunity.

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.

Viral-bacterial interactions in acute otitis media.

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.

Bacterial adherence in otitis media: determination of N-acetylgalactosamine (GalNAc) residues in the submucosal glands and surface epithelium of the normal and diseased Eustachian tube.

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.

Mycotic encephalitis, sinus osteomyelitis, and guttural pouch mycosis in a 3-year-old Arabian colt.

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.

Role of adenoids and adenoiditis in children with allergy and otitis media.

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.

Lysozyme M deficiency leads to an increased susceptibility to Streptococcus pneumoniae-induced otitis media.

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.

Tissular changes induced by Pseudomonas aeruginosa in an otitis media rat model with tubal obstruction.

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.

Progression of mycosis of the auditory tube diverticulum (guttural pouch) after arterial occlusion in a horse with contralateral temporohyoid osteoarthropathy.

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.

Fungal isolation and identification in 21 cases of guttural pouch mycosis in horses (1998-2002).

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.