Diseases of the middle ear in childhood

Subdural empyema-a rare complication of chronic otitis media: a case report

BACKGROUND

Subdural empyema is an extremely rare and fatal intracranial complication of chronic otitis media. Due to its rarity and vague symptoms, it is often diagnosed late if not completely missed; specially in developing countries where the diagnostic modalities are hardly available or accessible. To the best knowledge of the authors, this is a preliminary reported case of subdural empyema as a complication of chronic otitis media in Eritrea. It aims to provide vital information on the clinical presentation, preferred diagnostic modalities, and the proper management of such cases.

CASE REPORT

An 8 years old female patient from the Rashaida ethnic group presented with fever, right ear purulent discharge, right post-auricular swelling, and altered mental status. Prior to her admission, she had history of recurrent purulent discharge from her right ear for almost 2 years, and had been diagnosed with chronic otitis media. Upon admission her GCS was 13/15 which later on deteriorated to be 3/15 on day 3. MRI was done and showed a right fronto-tempo-parietal subdural empyema with mass effect, shifting the midline to the left. She was immediately started on empirical broad-spectrum antibiotics. After the diagnosis was made, craniotomy was done, and 30 ml of pus was removed from the subdural space. Culture and sensitivity of the pus obtained intraoperatively was done but produced no yield. Hence, she was continued on the empirically started antibiotics. The patient's condition was well improved by post-operative day 4.

CONCLUSION

It is important to have a high index of suspicion of intracranial complications in patients with history of chronic otitis media or other otologic complaints, who present with neurologic manifestations. Subdural empyema still being uncommon even among the intracranial complications of COM, it is often missed. Hence, timely diagnosis with MRI, immediate surgical evacuation of the empyema along with the prolonged administration of broad-spectrum antibiotics is highly recommended.

Phase variable acetylation of lipooligosaccharide modifies antibody production and opsonophagocytic killing of non-typeable Haemophilus influenzae

Non-typeable Haemophilus influenzae (NTHi) causes millions of infections each year. Though it is primarily known to cause otitis media, recent studies have shown NTHi is emerging as a primary pathogen for invasive infection, prompting the need for new vaccines and treatments. Lipooligosaccharide (LOS) has been identified as a potential vaccine candidate due to its immunogenic nature and outer membrane localization. Yet, phase variable expression of genes involved in LOS synthesis has complicated vaccine development. In this study, we used a chinchilla model of otitis media to investigate how phase variation of oafA, a gene involved in LOS biosynthesis, affects antibody production in response to infection. We found that acetylation of LOS by OafA inhibited production of LOS-specific antibodies during infection and that NTHi expressing acetylated LOS were subsequently better protected against opsonophagocytic killing. These findings highlight the importance of understanding how phase variable modifications might affect vaccine efficacy and success.

A review of 149 Divers Alert Network emergency call records involving diving minors

INTRODUCTION

Minors have been scuba diving for decades, and while the initial concerns about potential long-term complications related to bone development appear to be unfounded, the incidence of scuba diving injuries among them has been poorly studied.

METHODS

We reviewed 10,159 cases recorded in the DAN Medical Services call centre database from 2014 through 2016 and identified 149 cases of injured divers younger than 18 years. Records were analysed for case categorisation on the most common dive injuries. Information about demographics, level of training, risk factors, and relevant behavioural aspects were collected when available.

RESULTS

While the most common reason for the call was to rule out decompression sickness, the majority of cases pertained to ear and sinus issues. However, 15% of the dive-related injuries involving minors had a final diagnosis of pulmonary barotrauma (PBt). While no reliable data is available on the incidence of PBt in adult divers, the authors' impression based on personal experience suggests that the number of cases of PBt in minors trends higher than in the general diving population. The narratives on some relevant records describe unmanageable levels of anxiety leading to panic.

CONCLUSIONS

Based on the results and narratives on these cases, it is reasonable to infer that psychological immaturity, suboptimal management of adverse situations, and inadequate supervision might have led to severe injuries among these minor divers.

The association between Helicobacter pylori and chronic otitis media with effusion

PURPOSE

Chronic otitis media with effusion (COME) is a common condition in children and a leading cause for hearing loss and ventilation tubes (VT) insertion. Among other risk factors, it is suggested that Helicobacter pylori (H. pylori) infection may have a role in the pathogenesis of COME. Previous studies have reached different results, and therefore, there is a need for further data on the relationship between H. pylori infection and COME development in children. Our objective is to investigate the presence of H. pylori in the middle-ear fluid (MEF) from children with COME.

METHODS

A Comparative cross-sectional study. Children ≤ 18 years were included. The study group included children diagnosed with COME and required VT insertion. The control group included children with acute otitis media (AOM) who required myringotomy in the emergency room. Middle-ear fluid samples were sent for both culture and bacterial identification using polymerase chain reaction (PCR) testing.

RESULTS

A total of 43 children were included. Eighteen with COME (median age 4 years, IQR 3-6), and 25 with AOM (median age 1 year, IQR 1-2). All samples were cultured for H. pylori. Twenty-two samples underwent H. pylori PCR testing of them, 12 samples from children with COME, and 10 from children with AOM. All cultures and PCR tests results were negative for H. pylori.

CONCLUSIONS

Our results suggest that H. pylori does not have a role in the pathogenesis of COME. Future larger studies are needed to investigate whether H. pylori has a role in the pathogenesis of COME.

Hearing Screening among First-Grade Children in Rural Areas and Small Towns in Małopolskie Voivodeship, Poland

Undiagnosed hearing deficits hamper a child’s ability to learn. Hearing screening in school aged children helps detect educationally significant hearing loss and prevents negative impacts on academic achievement. The main purpose of this study was to improve early detection and assess the incidence of hearing disorders in first-graders from rural areas and small towns in the Małopolskie Voivodeship of Poland. There were 5029 children aged 6–7 years. Hearing thresholds were measured over the frequency range 0.5–8 kHz. A result was considered positive (abnormal) if the hearing threshold was worse than 20 dB HL at one or more frequencies. The prevalence of hearing loss was estimated in terms of four-frequency hearing loss, high-frequency hearing loss, and low-frequency hearing loss. Parents filled in a brief audiological questionnaire. The analysis was performed using IBM SPSS Statistics, version 24. Of all the children, 20.5% returned a positive result and were referred for further audiological diagnoses. The estimated prevalence of hearing loss was 11.6%, made up of 6.5% with FFHL, 7.6% with HFHL, and 8.2% with LFHL. This study showed that large numbers of children in the district had hearing problems. Adoption of hearing screening in primary schools is recommended as a routine procedure within preventive pediatric health care.

Children and diving, a guideline

Scuba diving is an increasingly popular recreational activity in children and adolescents. During the dive medical examination aspects of human physiology, anatomy, and psychology, that differ between adults and children, deserve our special attention. For example, lack of mental maturity, diminished Eustachian tube function and heat loss can pose problems during diving. It is important that children who wish to take up scuba diving are seen by a dive physician, with extra attention to Eustachian tube function. In children, asthma, bronchial hyperreactivity, pulmonary hypertension, and right-to-left shunts are contra-indications for scuba diving. Attention deficit hyperactivity disorder is a relative contra-indication. This article provides a review of the current literature and presents recommendations for recreational diving in children and adolescents. These recommendations are based solely on 'expert' opinion and were accepted by the Dutch Society of Diving and Hyperbaric Medicine in 2020.

Controlled release of ciprofloxacin and ceftriaxone from a single ototopical administration of antibiotic-loaded polymer microspheres and thermoresponsive gel

Acute otitis media (AOM) is the main indication for pediatric antibiotic prescriptions, accounting for 25% of prescriptions. While the use of topical drops can minimize the administered dose of antibiotic and adverse systemic effects compared to oral antibiotics, their use has limitations, partially due to low patient compliance, high dosing frequency, and difficulty of administration. Lack of proper treatment can lead to development of chronic OM, which may require invasive interventions. Previous studies have shown that gel-based drug delivery to the ear is possible with intratympanic injection or chemical permeation enhancers (CPEs). However, many patients are reluctant to accept invasive treatments and CPEs have demonstrated toxicity to the tympanic membrane (TM). We developed a novel method of delivering therapeutics to the TM and middle ear using a topical, thermoresponsive gel depot containing antibiotic-loaded poly(lactic-co-glycolic acid) microspheres. Our in vitro and ex vivo results suggest that the sustained presentation can safely allow therapeutically relevant drug concentrations to penetrate the TM to the middle ear for up to 14 days. Animal results indicate sufficient antibiotic released for treatment from topical administration 24h after bacterial inoculation. However, animals treated 72h after inoculation, a more clinically relevant treatment practice, displayed spontaneous clearance of infection as is also often observed in the clinic. Despite this variability in the disease model, data suggest the system can safely treat bacterial infection, with future studies necessary to optimize microsphere formulations for scaled up dosage of antibiotic as well as further investigation of the influence of spontaneous bacterial clearance and of biofilm formation on effectiveness of treatment. To our knowledge, this study represents the first truly topical drug delivery system to the middle ear without the use of CPEs.

Results of hearing screening of school-age children in Bishkek, Kyrgyzstan

Aim:

To gauge the prevalence of hearing loss in school children in Bishkek, Kyrgyzstan, and refer pupils with positive results for further diagnostic testing.

Background:

According to WHO data, hearing disorders are common in school-age children. Screening for hearing loss is an important preventative tool, helping to avoid further complications. Expenditure that supports early child development can reduce future outlay on health care and social services; it can eliminate disability problems, education deficits, and social maladaptation in later adult life.

Methods:

Pure-tone air-conduction hearing thresholds were obtained at 0.5–8 kHz. The results of the hearing screening examination were regarded as positive if pure-tone thresholds were higher than 20 dB HL in one or both ears at one or more of the test frequencies. Data were also obtained from follow-up visits of children who failed the initial screening.

Findings:

This study included 452 children aged 7–13 years old. Based on audiograms, screening showed that 123 (27.2%) of the children had hearing impairment. The study has important implications for clinical practice and health policy. There is a need for systematic monitoring of hearing status among children of this age, and parents and educators need to be made aware of the significance of hearing loss.

Bacterial aetiology of chronic otitis media with effusion in children - risk factors

Background

Otitis media with effusion (OME) may occur spontaneously because of poor Eustachian tube function or as an inflammatory response following AOM. Bacterial involvement in OME has been widely reported, with various available methods to identify pathogens from middle ear effusion, including traditional culture methods and polymerase chain reaction (PCR).

Objectives

The primary goal of this study was to evaluate the bacteriological profile of middle ear effusion in OME. Risk factors of the bacterial OME aetiology were also identified.

Methods

Middle ear effusions (MEF) from 50 children, aged 2–8 years, diagnosed by ENT and undergoing routine tympanostomy tube placement were collected. MEF samples were streaked on standard microbiological media. Next, DNA was isolated from MEF samples and analysed with multiplex PCR for Streptococcus pneumoniae, Haemophilus influenzae, Moraxella catarrhalis and Alloiococcus otitidis.

Results

In multiplex PCR assay 37 (74%) of 50 children were positive for at least one of the four microorganisms. In 27.0% positive children multiple bacterial pathogens were identified. A. otitidis was the most frequently identified in positive MEF children (59.5%). By multiplex PCR, H. influenzae, S. pneumoniae and M. catarrhalis were detected in 24, 18 and 8% of OME patients, respectively. There was significant association between bilateral infection and H. influenzae aetiology of OME.

Conclusions

Overall we found OME predominantly a single otopathogen infection caused mainly by A. otitidis, which is difficult in identification using standard culture method, ahead to S. pneumoniae and H. influenzae. However, one third of MEF samples had multiple bacterial pathogens.

Calculated parenteral initial treatment of bacterial infections: Infections in the ear, nose, throat and mouth and jaw area

This is the sixth chapter of the guideline "Calculated initial parenteral treatment of bacterial infections in adults - update 2018" in the 2nd updated version. The German guideline by the Paul-Ehrlich-Gesellschaft für Chemotherapie e.V. (PEG) has been translated to address an international audience. The chapter deals with the antibacterial treatment of more severe infections of the ear, the nose, the throat and the maxillofacial region, including odontogenic and salivary gland infections.

In Vitro Investigation of the Antibacterial Activity of Nigella sativa Oil on Some of the Most Commonly Isolated Bacteria in Otitis Media and Externa

Objective

This study aimed to evaluate the antibacterial efficacy of Nigella sativa (NS) seed oil against the most frequently isolated infectious bacteria of the middle and external ear.

Materials and Methods

The in vitro antibacterial activity of NS oil was evaluated against 34 clinical isolates of Streptococcus pneumoniae, 32 clinical isolates of Moraxella catarrhalis, 32 clinical isolates of Haemophilus influenzae, and 32 clinical isolates of Pseudomonas aeruginosa. Staphylococcus aureus, Escherichia coli, and P. aeruginosa were also evaluated for their sensitivity to the NS oil. The minimum inhibitory concentration (MIC) of the NS oil was determined via a broth dilution technique. Serial solutions were prepared in a Mueller Hinton-F broth to achieve an ultimate concentration of NS oil within the microplate wells ranging from 256 μg/mL to 0.25 μg/mL. The growth control wells and medium were used for each bacterial strain, and the microplates were incubated at 35°C for 24 h. Those wells having no visible growth and the lowest concentration of NS oil were accepted as showing the MIC.

Results

In this study, a comparison was made between NS oil and the various antibiotics known to be effective against the bacterial strains mentioned above. The NS was shown to have bactericidal activity against H. influenzae, M. catarrhalis, and S. pneumoniae. However, the NS was not found to be effective against P. aeruginosa at any concentration.

Conclusion

The results of this laboratory-based study support the use of NS oil as an alternative treatment for ear infections. However, it is necessary to conduct clinical studies to evaluate the antibacterial efficacy of NS oil on patients with ear infections.

Altered Middle Ear Microbiome in Children With Chronic Otitis Media With Effusion and Respiratory Illnesses

Chronic otitis media with effusion (COME) is a common childhood disease characterized by an accumulation of fluid behind the eardrum. COME often requires surgical intervention and can also lead to significant hearing loss and subsequent learning disabilities. Recent characterization of the middle ear fluid (MEF) microbiome in pediatric patients has led to an improved understanding of the microbiota present in the middle ear during COME. However, it is not currently known how the MEF microbiome might vary due to other conditions, particularly respiratory disorders. Here, we apply an amplicon sequence variant (ASV) pipeline to MEF 16S rRNA high-throughput sequencing data from 50 children with COME (ages 3–176 months) undergoing tube placement. We achieve a more detailed taxonomic resolution than previously reported, including species and genus level resolution. Additionally, we provide the first report of the functional roles of the MEF microbiome and demonstrate that despite high taxonomic diversity, the functional capacity of the MEF microbiome remains uniform between patients. Furthermore, we analyze microbiome differences between children with COME with and without a history of lower airway disease (i.e., asthma or bronchiolitis). The MEF microbiome was less diverse in participants with lower airway disease than in patients without, and phylogenetic β-diversity (weighted UniFrac) was significantly different based on lower airway disease status. Differential abundance between patients with lower airway disease and those without was observed for the genera Haemophilus, Moraxella, Staphylococcus, Alloiococcus, and Turicella. These findings support previous suggestions of a link between COME and respiratory illnesses and emphasize the need for future study of the middle ear and respiratory tract microbiomes in diseases such as asthma and bronchiolitis.

Surface Motion of Tympanic Membrane in a Chinchilla Model of Acute Otitis Media

The conductive hearing loss caused by acute otitis media (AOM) is commonly related to a reduction of the tympanic membrane (TM) mobility in response to sound stimuli. However, spatial alterations of the TM surface motion associated with AOM have rarely been addressed. In this study, the TM surface motion was determined using scanning laser Doppler vibrometry (SLDV) in a chinchilla model of AOM. The AOM was established by transbullar injection of nontypeable Haemophilus influenzae. The TM surface vibration was measured in control (uninfected) animals and two AOM groups of animals: 4 days (4D) and 8 days (8D) post inoculation. To quantify the effect of middle ear pressure in those infected ears, the SLDV measurement was first conducted in unopened AOM ears and then in middle ear pressure released ears. Results showed that middle ear infection generally reduced the TM displacement across the entire surface, but the reduction in the umbo displacement over the time course, from 4 to 8 days post inoculation, was less than the reduction in the displacement at the center of each quadrant. The presence of middle ear fluid shifted the occurrence of traveling-wave-like motion on the TM surface to lower frequencies. The observation of the spatial variations of TM surface motion from this study will help refine our understanding of the middle ear sound transmission characteristics in relation to AOM.

Air pollution influences the incidence of otitis media in children: A national population-based study

Background

Otitis media (OM) is a major reason for children’s visits to physicians and a major cause of their being treated with antibiotics. It not only causes economic burdens but also influences hearing, speech, and education. To our knowledge, no nationwide population-based study has assessed the association between air pollution and OM. Therefore, this study evaluated the association between air pollution levels and the incidence of OM.

Methods

We identified cases of OM that occurred in South Korea between January 2011 and December 2012 from the Korea National Health Insurance Service-National Sample Cohort database, and evaluated its relationship with five air pollutants: particulate matter (PM₁₀, particulates ≤10 μm in diameter), nitrogen dioxide (NO₂), ozone (O₃), sulfur dioxide, and carbon monoxide. Associations between the weekly incidence of OM and the five air pollutants were analyzed using generalized estimating equations. Conditional logistic regression analysis was used to obtain odds ratios (ORs) and their 99.9% Bonferroni-corrected confidence intervals after adjusting for gender, age, season, and region.

Results

We based our analysis on 160,875 hospital visits for OM by children aged <15 years. Correlations with higher concentrations of the five pollutants showed higher ORs than did the reference values at most time lags. PM₁₀ had the largest influence on the OM incidence at a time lag of 0 weeks, whereas NO₂ and O₃ had the largest impacts on OM incidence at time lags of 1 and 4 weeks, respectively.

Conclusion

These findings support the notion that the incidence of OM is associated with ambient air pollution.

Stenting the Eustachian tube to treat chronic otitis media - a feasibility study in sheep

BACKGROUND

Untreated chronic otitis media severely impairs quality of life in affected individuals. Local destruction of the middle ear and subsequent loss of hearing are common sequelae, and currently available treatments provide limited relief. Therefore, the objectives of this study were to evaluate the feasibility of the insertion of a coronary stent from the nasopharynx into the Eustachian tube in-vivo in sheep and to make an initial assessment of its positional stability, tolerance by the animal, and possible tissue reactions.

METHODS

Bilateral implantation of bare metal cobalt-chrome coronary stents of two sizes was performed endoscopically in three healthy blackface sheep using a nasopharyngeal approach. The postoperative observation period was three months.

RESULTS

Stent implantation into the Eustachian tube was feasible with no intra- or post-operative complications. Health status of the sheep was unaffected. All stents preserved their cylindrical shape. All shorter stents remained in position and ventilated the middle ear even when partially filled with secretion or tissue. One of the long stents became dislocated toward the nasopharynx. Both of the others remained fixed at the isthmus but appeared to be blocked by tissue or secretion. Tissue overgrowth on top of the struts of all stents resulted in closure of the tissue-lumen interface.

CONCLUSION

Stenting of the Eustachian tube was successfully transferred from cadaver studies to an in-vivo application without complications. The stent was well tolerated, the middle ears were ventilated, and clearance of the auditory tube appeared possible. For fixation, it seems to be sufficient to place it only in the cartilaginous part of the Eustachian tube.

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Question L’otite moyenne aiguë compte parmi les infections les plus communes durant l’enfance. La prescription systématique d’antibiotiques a entraîné des effets indésirables et une résistance bactérienne aux antibiotiques. J’ai entendu dire qu’une « attente vigilante » est une bonne stratégie pour réduire ce problème potentiel chez les enfants de plus de 6 mois. Me faudrait-il l’adopter dans ma pratique clinique?

Réponse Une attente vigilante est une stratégie appropriée chez certains enfants souffrant d’une otite moyenne aiguë bénigne; elle consiste à s’abstenir de donner des antibiotiques et à observer l’enfant pour savoir s’il y a une amélioration clinique. Il faut fournir sans délai des antibiotiques si l’infection de l’enfant s’aggrave ou s’il ne se produit pas d’amélioration dans les 24 à 48 heures. Les lignes directrices et la plupart des études en cours corroborent ces recommandations. Il importe de choisir de façon appropriée le schéma thérapeutique, la dose, la fréquence et la durée du traitement.

Antibiotic therapy for children with acute otitis media

Question Acute otitis media is one of the most common infections in childhood. Routine prescription of antibiotics has led to adverse events and bacterial resistance to antibiotics. I have heard that "watchful waiting" is a good strategy to reduce this potential problem in children older than 6 months of age. Should I apply this strategy in my clinical practice? Answer Watchful waiting can be applied in selected children with nonsevere acute otitis media by withholding antibiotics and observing the child for clinical improvement. Antibiotics should be promptly provided if the child's infection worsens or fails to improve within 24 to 48 hours. Guidelines and most ongoing studies support these recommendations. Correct choice of regimen, dose, frequency, and length of treatment are all important.

MDCT of the temporal bone and audiological findings of pediatric acquired cholesteatoma

Cholesteatoma is a benign epithelial lesion affecting the middle ear and/or mastoid process, causing otorrhea and hearing loss. Here, we retrospectively evaluated the temporal multidetector computed tomography and audiological findings of acquired cholesteatoma in children. Forty-three patients younger than 18 years old with middle ear acquired cholesteatoma were evaluated with regard to their clinical symptoms, temporal multidetector computed tomography findings, and audiometry results. The multidetector computed tomography findings were classified according to the site-ossicle-complication classification, and the relationships between the clinical, radiological, and audiological findings were evaluated. Only one patient had pars tensa cholesteatoma, and the remaining had attic cholesteatoma. The most common site-ossicles-complication classifications were S4 (acquired cholesteatoma involving four sites), O1 (involving one ossicle), and C0 (no complications), and the most common complaint was hearing loss, followed by otorrhea. There were no statistically significant relationships between the site of involvement and ossicle involvement. In addition, there were no statistically significant differences according to the S classification in either the air conduction or air-bone-gap levels; however, these levels differed statistically significantly with increasing ossicle involvement. Early diagnosis and treatment are essential to prevent hearing loss and serious complications in cases of acquired cholesteatoma. Therefore, it is important to evaluate the temporal multidetector computed tomography and audiological findings to accurately diagnose acquired cholesteatoma in children.

Vitamin D Levels in Children with Adenotonsillar Hypertrophy and Otitis Media with Effusion

INTRODUCTION

Vitamin D has been suggested to play a considerable role in the function of the immune system in various infectious, inflammatory, and autoimmune conditions. Otitis media with effusion (OME), defined as the presence of non-purulent fluid within the middle ear without signs or symptoms of suppurative otitis media, has a number of inflammatory predisposing factors. This study was designed to explore the association between vitamin D deficiency and OME.

MATERIALS AND METHODS

In this cross-sectional study, 74 children aged 2-7 years with an obstructive indication for adenotonsillectomy were included. Patients were divided into two groups based on the need for ventilation tube insertion for OME. Thirty-two children were enrolled in the OME group and 42 in the control group. The mean vitamin D level was compared between the two groups.

RESULTS

Mean vitamin D concentration in all patients was 11.96±5.85 ng/ml (9.79±4.36 ng/ml in the OME group and 13.61±6.33 ng/ml in the control group; P=0.003). There was also a significant difference in levels of vitamin D in patients referred in winter (9.0±2.94 ng/ml) compared with the summer (19.85±4.21 ng/ml; P=0.001). Data analyzed based on the season in which the patients were referred showed no significant difference between the OME and the control group.

CONCLUSION

Although our results showed lower serum levels of vitamin D in OME patients, the difference was not significant when seasons were taken into consideration. Therefore, the season is an important confounding factor in any research related to vitamin D due to the effect of sun-induced vitamin D.

Otopathogenic Pseudomonas aeruginosa Enters and Survives Inside Macrophages

Otitis media (OM) is a broad term describing a group of infectious and inflammatory disorders of the middle ear. Despite antibiotic therapy, acute OM can progress to chronic suppurative otitis media (CSOM) characterized by ear drum perforation and purulent discharge. Pseudomonas aeruginosa is the most common pathogen associated with CSOM. Although, macrophages play an important role in innate immune responses but their role in the pathogenesis of P. aeruginosa-induced CSOM is not known. The objective of this study is to examine the interaction of P. aeruginosa with primary macrophages. We observed that P. aeruginosa enters and multiplies inside human and mouse primary macrophages. This bacterial entry in macrophages requires both microtubule and actin dependent processes. Transmission electron microscopy demonstrated that P. aeruginosa was present in membrane bound vesicles inside macrophages. Interestingly, deletion of oprF expression in P. aeruginosa abrogates its ability to survive inside macrophages. Our results suggest that otopathogenic P. aeruginosa entry and survival inside macrophages is OprF-dependent. The survival of bacteria inside macrophages will lead to evasion of killing and this lack of pathogen clearance by phagocytes contributes to the persistence of infection in CSOM. Understanding host-pathogen interaction will provide novel avenues to design effective treatment modalities against OM.

Tympanometric measurements in conscious sheep - a diagnostic tool for pre-clinical middle ear implant studies

OBJECTIVE

To investigate and establish the use of tympanometry in conscious sheep to provide a means of objective assessment of tympanic membrane integrity, middle ear ventilation and functioning of the Eustachian tube (ET).

DESIGN

After conditioning the sheep for four weeks, tympanometric measurements at 226 Hz were carried out weekly for 13 weeks. Before measurements, the external ear canal had been cleaned. Resultant curves were classified according to human reference values.

STUDY SAMPLE

Tests were performed on 12 female blackface sheep.

RESULTS

After cleaning of the external ear canal under otoscopic control, tympanic membranes were intact with no evidence of acute or chronic middle ear inflammation, middle ear effusion or retraction. Cleaning ensured valid, objective and reproducible measurements. As the majority of normal tympanograms were notched without the appearance of any malformation, an additional tympanogram type (A_N) was introduced. The notched appearance can most likely be explained by the anatomy of the middle ear of the sheep and the test frequency that was used.

CONCLUSION

The current study demonstrated how tympanometry can be used to evaluate treatment modalities for middle ear and ET function in conscious sheep. This provided a large animal model for further human research in otology.

Terahertz otoscope and potential for diagnosing otitis media

We designed and fabricated a novel terahertz (THz) otoscope to help physicians to diagnose otitis media (OM) with both THz diagnostics and conventional optical diagnostics. We verified the potential of this tool for diagnosing OM using mouse skin tissue and a human tympanic membrane samples prior to clinical application.

Pseudomonas aeruginosa Activates PKC-Alpha to Invade Middle Ear Epithelial Cells

Otitis media (OM) is a group of complex inflammatory disorders affecting the middle ear which can be acute or chronic. Chronic suppurative otitis media (CSOM) is a form of chronic OM characterized by tympanic membrane perforation and discharge. Despite the significant impact of CSOM on human population, it is still an understudied and unexplored research area. CSOM is a leading cause of hearing loss and life-threatening central nervous system complications. Bacterial exposure especially Pseudomonas aeruginosa is the most common cause of CSOM. Our previous studies have demonstrated that P. aeruginosa invades human middle ear epithelial cells (HMEECs). However, molecular mechanisms leading to bacterial invasion of HMEECs are not known. The aim of this study is to characterize the role of PKC pathway in the ability of P. aeruginosa to colonize HMEECs. We observed that otopathogenic P. aeruginosa activates the PKC pathway, specifically phosphorylation of PKC-alpha (PKC-α) in HMEECs. The ability of otopathogenic P. aeruginosa to phosphorylate PKC-α depends on bacterial OprF expression. The activation of PKC-α was associated with actin condensation. Blocking the PKC pathway attenuated the ability of bacteria to invade HMEECs and subsequent actin condensation. This study, for the first time, demonstrates that the host PKC-α pathway is involved in invasion of HMEECs by P. aeruginosa and subsequently to cause OM. Characterizing the role of the host signaling pathway in the pathogenesis of CSOM will provide novel avenues to design effective treatment modalities against the disease.