The Adenoids but Not the Palatine Tonsils Serve as a Reservoir for Bacteria Associated with Secretory Otitis Media in Small Children

Bacteriology of Adenoids and Tonsils in Children With Recurrent Adenotonsillitis

INTRODUCTION

Recurrent adenotonsillitis (AT) commonly affects children and may be associated with various complications. Infections are common etiology, and microbial profiles may vary widely in different cases. In this study, we evaluated the bacterial profile and antibiotic sensitivity of pathogens identified in tonsil and adenoid core cultures in children with recurrent AT.

METHODS

In this cross-sectional, observational study, culture and antibiotic sensitivity were performed from tonsil and adenoid core samples obtained after adenotonsillectomy of children (5 to 18 years) with recurrent AT. Children who had received antibiotics within one week before surgery were excluded. Drug sensitivity was performed only for drugs available on the hospital panel list.

RESULTS

Bacterial growth was observed in 83 (91.2%) tonsil core cultures (n=91) and 43 (79.6%) adenoid core cultures (n=54). In the tonsil and adenoid core cultures, poly-microbial growth was seen in 25 (27.0%) and 11 (25.6%) children, respectively. From the tonsil core cultures, the majority of the bacteria were sensitive to ciprofloxacin, ampicillin, piperacillin-tazobactam, cefoperazone-sulbactam, ceftazidime, cefotaxime, levofloxacin. From the adenoid core culture, the majority of the bacteria were sensitive to ciprofloxacin, ampicillin, piperacillin-tazobactam, cefoperazone-sulbactam, cephalexin, and cefotaxime.

CONCLUSION

In recurrent AT, polymicrobial growth is not uncommon in both tonsil and adenoid core cultures. Identifying the correct pathogens and their antibiotic sensitivity patterns can help plan treatment strategies for the effective management of recurrent AT.

Analysis of factors that influence the occurrence of otitis media with effusion in pediatric patients with adenoid hypertrophy

Objective

Adenoid hypertrophy (AH) and otitis media with effusion (OME) are common pediatric otolaryngological diseases and often occur concurrently. The purpose of this study was to comprehensively analyze the factors that influence the occurrence of OME pediatric patients with AH.

Methods

Patients younger than 12 years with AH, who were hospitalized for treatment at Beijing Tsinghua Changgung Hospital in Beijing, China, between March 2018 and February 2022 were enrolled. The patients were divided into an AH group and an AH + OME group based on the presence of OME. The authors collected the following clinical data for univariable analysis: sex; age; body mass index (BMI); comorbid nasal congestion/rhinorrhea, recurrent tonsillitis, or allergic rhinitis (AR); adenoid and tonsil grade; tonsillar hypertrophy; food/drug allergy; history of adenoidectomy and congenital diseases; breastfeeding status; preterm birth; exposure to environmental tobacco smoke (ETS); family history of adenotonsillectomy, otitis media, and AR; main data of polysomnography and oropharyngeal conditional pathogen culture data of some patients. Univariate analysis was performed as a basis for logistic regression analysis.

Results

A total of 511 children (329 boys and 182 girls) were included, their mean age was 5.37 ± 2.10 years. Of them, 407 (79.6%) were in the AH group and 104 (20.4%) in the AH + OME group. Univariate analysis revealed statistically significant differences in age, BMI, adenoid grade, AR, breastfeeding status, and ETS exposure between the two groups. Multivariate stepwise logistic regression analysis showed that age, adenoid grade, AR, breastfeeding status, and ETS influenced the occurrence of OME in pediatric patients with AH. The risk of OME decreased with increasing age. High adenoid grade, ETS exposure, and comorbid AR were risk factors for OME in pediatric patients with AH, but breastfeeding was a protective factor. The final analytical results of the oropharyngeal conditional pathogen culture data showed that Streptococcus pneumoniae positivity was associated with OME in AH.

Conclusion

The pathogenesis of AH with OME is complex. Young age, high adenoid grade, ETS exposure, non-breastfed status, comorbid AR, and the presence of S. pneumoniae in the oropharynx are risk factors for OME in pediatric patients with AH.

Changes in the oral and nasal microbiota in pediatric obstructive sleep apnea

Background

Several clinical studies have demonstrated that pediatric obstructive sleep apnea (OSA) is associated with dysbiosis of airway mucosal microbiota. However, how oral and nasal microbial diversity, composition, and structure are altered in pediatric OSA has not been systemically explored.

Methods

30 polysomnography-confirmed OSA patients with adenoid hypertrophy, and 30 controls who did not have adenoid hypertrophy, were enrolled. Swabs from four surface oral tissue sites (tongue base, soft palate, both palatine tonsils, and adenoid) and one nasal swab from both anterior nares were collected. The 16S ribosomal RNA (rRNA) V3-V4 region was sequenced to identify the microbial communities.

Results

The beta diversity and microbial profiles were significantly different between pediatric OSA patients and controls at the five upper airway sites. The abundances of Haemophilus, Fusobacterium, and Porphyromonas were higher at adenoid and tonsils sites of pediatric patients with OSA. Functional analysis revealed that the differential pathway between the pediatric OSA patients and controls involved glycerophospholipids and amino acid metabolism.

Conclusions

In this study, the oral and nasal microbiome of pediatric OSA patients exhibited certain differences in composition compared with the controls. However, the microbiota data could be useful as a reference for studies on the upper airway microbiome.

The influence of nasal and oropharyngeal mucosal dysbiosis on the condition of the middle ear in children with congenital cleft palate

Disturbance of the microbiocenosis of the nasal cavity and oropharynx in children with congenital cleft palate presents serious therapeutic difficulties. Pathobionts colonizing the upper respiratory tract and chronic adenoiditis pose a threat of acute purulent otitis media and chronic otitis media with effusion. The authors studied nasal and oropharyngeal mucosal dysbiosis in patients before elective uranoplasty and the effect of dysbiotic manifestations on the condition of the middle ear in the postoperative period. The results of microbiological examination of 80 swabs from the nasal cavity and oropharynx in patients with congenital cleft palate were analyzed. Among the culture-positive results in patients in clinical and laboratory remission of ENT-infections dysbiosis of 2–3 degrees prevails, the presence of bacterial-bacterial and bacterial-fungal associations is often noted, the predominance of gram-negative microflora is noted. There was an increase in the frequency of perforations of the tympanic membrane in the presence of bacterial and fungal associations, the appearance of retraction pockets in the presence of gram-negative microflora, the relationship between grade 3 dysbiosis and the appearance of purulent otitis media after uranoplasty were revealed.

Conclusion. Disturbance of microbiocenosis in patients with congenital cleft palate before uranoplasty requires the inclusion of a microbiological study in the preoperative preparation schedule and a personalized approach to perioperative antibiotic prophylaxis. 

Predominant Bacterial and Viral Otopathogens Identified Within the Respiratory Tract and Middle Ear of Urban Australian Children Experiencing Otitis Media Are Diversely Distributed

Background

Otitis media (OM) is one of the most common infections in young children, arising from bacterial and/or viral infection of the middle ear. Globally, Streptococcus pneumoniae and non-typeable Haemophilus influenzae (NTHi) are the predominant bacterial otopathogens. Importantly, common upper respiratory viruses are increasingly recognized contributors to the polymicrobial pathogenesis of OM. This study aimed to identify predominant bacteria and viruses in the nasopharynx, adenoids and middle ears of peri-urban/urban South-East Queensland Australian children, with and without clinical history of chronic otitis media with effusion (COME) and/or recurrent acute otitis media (RAOM).

Methods

Sixty children, 43 diagnosed with OM and 17 controls with no clinical history of OM from peri-urban/urban South-East Queensland community were recruited to the study. Respiratory tract bacterial and viral presence were examined within nasopharyngeal swabs (NPS), middle ear effusions (MEE) and adenoids, using real-time polymerase chain reaction (RT-PCR) and bacterial culture.

Results

At least one otopathogen present was observed in all adenoid samples, 86.1% and 82.4% of NPS for children with and without OM, respectively, and 47.1% of the MEE from the children with OM. NTHi was the most commonly detected bacteria in both the OM and control cohorts within the adenoids (90.0% vs 93.8%), nasopharynx (67.4% vs 58.8%) respectively, and in the MEE (OM cohort 25.9%). Viruses were detected in all adenoid samples, 67.4% vs 47.1% of the NPS from the OM and control cohorts, respectively, and 37% of the MEE. Rhinovirus was the predominant virus identified in the adenoids (85.0% vs 68.8%) and nasopharynx (37.2% vs 41.2%) from the OM and control cohorts, respectively, and the MEE (19.8%).

Conclusions

NTHi and rhinovirus are predominant otopathogens within the upper respiratory tract of children with and without OM from peri-urban and urban South-East Queensland, Australia. The presence of bacterial otopathogens within the middle ear is more predictive of concurrent URT infection than was observed for viruses, and the high otopathogen carriage within adenoid tissues confirms the complex polymicrobial environment in children, regardless of OM history.

Assessment of sleep-disordered breathing in pediatric otitis media with effusion

BACKGROUND

Given the role of adenoid in the pathogenesis of otitis media with effusion (OME) and sleep-disordered breathing (SDB), the present study aimed to investigate the sleep quality and the impact of adenoidectomy on improvement of sleep symptoms in children with OME.

METHODS

Children with SDB or OME, aged 3-12 years, were prospectively enrolled before undergoing adenoidectomy in a tertiary medical center. The symptom severity of obstructive sleep apnea syndrome (OSAS) was evaluated by OSA-18 questionnaire on the day before and 6 months after surgery.

RESULTS

In total, 79 pediatric patients including 50 children with SDB and 29 children with OME were enrolled. The mean total OSA-18 score was 56.5 ± 15.1 and ten (34.5%) children experienced moderate to severe symptoms of OSAS as indicated by OSA-18 score ≥ 60 in OME group. After surgery, patients in both SDB and OME groups experienced improvement (both p < 0.001) and presented no difference in the scores of OSA-18. The proportional change in OSA-18 scores after surgery was related to pre-operative OSA-18 scores and BMI in OME patients (r_s = 0.400 and 0.542, p = 0.047 and 0.008), and to pre-operative OSA-18 scores in patients with SDB (r_s = 0.393, p = 0.008).

CONCLUSION

Children with OME experienced significant symptoms of OSAS and associated impairment of quality of life. Adenoidectomy is effective in the improvement of sleep symptoms in these patients. Comprehensive assessment of sleep breathing as planning surgery for OME children is suggested.

Characteristics of the bacterial microbiota in the upper respiratory tract of children

PURPOSE

The respiratory tract microbiota are deemed as the gatekeeper to health. Consequently, microbiota dysbiosis can lead to the development of diseases. To identify the exact origins of the localized pathogenic bacteria, we investigated bacterial composition in the upper airway tract.

METHODS

Separate mucosal swabs were collected from nostril or oropharynx of each participant. Meanwhile, the lymphoid tissues including adenoids and tonsils were collected during operation. DNAs were exacted from all the samples for the following 16S rRNA analysis.

RESULTS

At the phylum level, the basic bacterial structures in the adenoids, tonsils, oropharynx, and nostrils were generally similar: five main phyla Firmicutes, Proteobacteria, Bacteroidetes, Actinobacteria, and Fusobacteria form the majority of the microbiota. However, across these four sites, the microbiota composition differed. More specifically, the bacterial composition in the nostrils was unique. There, Firmicutes and Actinobacteria were the most abundant phyla, while Bacteroides and Fusobacteria were the least abundant. At the genus level, Staphylococcus, Dolosigranulum, Corynebacterium, and Moraxella were the most plentiful, while Fusobacteria was the least ample. Across all sites, Streptococcus displayed similar abundances. Fusobacteria exhibited higher abundances in the lymphoid tissues and oropharynx. Haemophilus and Neisseria were more plentiful in the tonsils and oropharynx. Notably, Klebsiella, which is normally localized to the gut, was abundant in the adenoids and tonsils.

CONCLUSION

Our data indicate that promising pathogenic bacteria originate from all sites in the upper airway. The upper tract lymphoid tissues, normally considered as immune organs, may also serve as reservoirs for pathogenic bacteria.

Tissue microbiota in nasopharyngeal adenoid and its association with pneumococcal carriage

The microbial colonization in the nasopharynx is a prerequisite for the onset of infectious diseases. For successful infection, pathogens should overcome host defenses as well as compete effectively with the resident microbiota. Hence, elucidating the richness and diversity of the microbiome at the site of pathogen colonization is pivotal. Here, we investigated the adenoidal tissue microbiota collected through adenoidectomy to evaluate the impact of Streptococcus pneumoniae. Prospectively, children with sleep-disordered breathing (SDB) and otitis media with effusion (OME) were enrolled. During adenoidectomy, the nasopharyngeal swab and adenoid tissues were collected to determine the pneumococcal carriage and tissue microbiota, using multiplex PCR and 16S ribosomal RNA (16S rRNA) pyrosequencing. A total of 66 pediatric patients comprising 38 children with SDB and 28 children with OME were enrolled. There was no difference between the bacterial cultures from the surface of the nasopharyngeal adenoid in the SDB and OME groups. Thirty-four samples (17 SDB and 17 OME) underwent 16S rRNA pyrosequencing and fulfilled the criteria for further analysis. The Shannon diversity index for the samples from the SDB patients was found to be higher than that observed for the samples from OME patients, although the difference was not significant (p = 0.095). The Shannon diversity index for the samples negative for the pneumococcal carriage was significantly higher than that for the samples positive for pneumococcal carriage (p = 0.038). Alloprevotella, Staphylococcus, Moraxella, and Neisseriaceae were significantly dominant in the samples positive for the pneumococcal carriage. Dialister was significantly less present in the adenoid tissue positive for the pneumococcal carriage. Streptococcus pneumoniae, one of the most common pathogens of the airway, significantly influences the composition and diversity of the microbiota in the nasopharyngeal adenoid. Thus, bacterial community analysis based on 16S rRNA pyrosequencing allows for better understanding of the relationship between the adenoidal microbial communities.

Microbiological investigation of samples collected from healthy middle ears during cochlear implant surgery

This study aimed to investigate the bacteriome in microscopically healthy middle ear mucosa using Next-generation sequencing (NGS) technology. A total of 60 middle ear washing fluids of pediatric and adult were obtained from 47 patients (35 children and 12 adults). Both children and adults with normal middle ears harbored diverse bacteriome. Seventeen different genera with a mean relative abundance of more than 1% were detected in all samples. Both in adult and children, the most abundant genus was Propionibacterium followed by Streptococcus, Staphylococcus, and Ralstonia. The species Propionibacterium acnes and Corynebacterium tuberculostearicum were significantly more abundant in the adult group. Although there were differences in the prevalence and relative abundance of some bacteria observed from adult and child groups, no specific genus or species was detected only in children or adults.

Role of Tonsillar Chronic Inflammation and Commensal Bacteria in the Pathogenesis of Pediatric OSA

Immune responses at the boundary between the host and the world beyond are complex and mucosal tissue homeostasis relies on them. Obstructive sleep apnea (OSA) is a syndrome suffered by children with hypertrophied tonsils. We have previously demonstrated that these tonsils present a defective regulatory B cell (Breg) compartment. Here, we extend those findings by uncovering the crucial role of resident pro-inflammatory B and T cells in sustaining tonsillar hypertrophy and hyperplasia by producing TNFα and IL17, respectively, in ex vivo cultures. Additionally, we detected prominent levels of expression of CD1d by tonsillar stratified as well as reticular epithelium, which have not previously been reported. Furthermore, we evidenced the hypertrophy of germinal centers (GC) and the general hyperplasia of B lymphocytes within the tissue and the lumen of the crypts. Of note, such B cells resulted mainly (IgG/IgM)⁺ cells, with some IgA⁺ cells located marginally in the follicles. Finally, by combining bacterial culture from the tonsillar core and subsequent identification of the respective isolates, we determined the most prevalent species within the cohort of OSA patients. Although the isolated species are considered normal oropharyngeal commensals in children, we confirmed their capacity to breach the epithelial barrier. Our work sheds light on the pathological mechanism underlying OSA, highlighting the relevance taken by the host immune system when defining infection versus colonization, and opening alternatives of treatment.

Correlations Between the Adenotonsillar Microbiome and Clinical Characteristics of Pediatric Patients With Snoring

Objectives

Few studies have reported combined analyses of the microbiome of the adenoids and tonsils in pediatric patients with snoring, and correlations of the adenotonsillar microbiome with clinical characteristics have not been evaluated to date. The aim of this study was to characterize the adenotonsillar microbiome and to determine its correlations with the subjective symptoms of pediatric patients with snoring and with levels of regional mucosal immune molecules.

Methods

Twenty-four children who underwent tonsillectomy with adenoidectomy owing to snoring were enrolled in this cross-sectional study conducted between August 2017 and December 2018. The microbiome of the adenoids and tonsils was characterized, and its alpha- and beta-diversity was determined. Clinical characteristics, including subjective discomfort during sleep (assessed using the obstructive sleep apnea-18 questionnaire), the presence of allergic rhinitis, concentrations of heat shock protein (Hsp)27, Hsp70, and interleukin-8 (IL-8) in lavage fluids, and white blood cell (WBC) counts, were measured.

Results

At the phylum level, the microbiome was not significantly different between the adenoids and tonsils; the alpha and beta indices were likewise not significantly different between these two regions. The alpha-diversity of the entire adenotonsillar microbiome was associated with sex, emotional stress, and IL-8 levels in the tonsil lavage fluids. Beta-diversity was associated with Hsp27 levels in the tonsil lavage fluids and WBC counts. Multiple allergen simultaneous test results were not significant, although total serum immunoglobulin E levels were significantly associated with the beta-diversity of the adenotonsillar microbiome.

Conclusion

The data reported herein suggest, for the first time, that the adenotonsillar microbiome interacts with the regional mucosal immune system. The observed association of the microbiome with subjective discomfort is a novel finding that warrants further investigation.

Upper Respiratory Tract Microbiome and Otitis Media Intertalk: Lessons from the Literature

Otitis media (OM) is one of the most common diseases occurring during childhood. Microbiological investigations concerning this topic have been primarily focused on the four classical otopathogens (Streptococcus pneumoniae, Haemophilus influenzae, Moraxella catarrhalis and Streptococcus pyogenes) mainly because most of the studies have been conducted with culture-dependent methods. In recent years, the introduction of culture-independent techniques has allowed high-throughput investigation of entire bacterial communities, leading to a better comprehension of the role of resident flora in health and disease. The upper respiratory tract (URT) is a region of major interest in otitis media pathogenesis, as it could serve as a source of pathogens for the middle ear (ME). Studies conducted with culture-independent methods in the URT and ME have provided novel insights on the pathogenesis of middle ear diseases through the identification of both possible new causative agents and of potential protective bacteria, showing that imbalances in bacterial communities could influence the natural history of otitis media in children. The aim of this review is to examine available evidence in microbiome research and otitis media in the pediatric age, with a focus on its different phenotypes: acute otitis media, otitis media with effusion and chronic suppurative otitis media.

Panel 4: Recent advances in understanding the natural history of the otitis media microbiome and its response to environmental pressures

OBJECTIVE

To perform a comprehensive review of otitis media microbiome literature published between 1^st July 2015 and 30th June 2019.

DATA SOURCES

PubMed database, National Library of Medicine.

REVIEW METHODS

Key topics were assigned to each panel member for detailed review. Draft reviews were collated and circulated for discussion when the panel met at the 20th International Symposium on Recent Advances in Otitis Media in June 2019. The final draft was prepared with input from all panel members.

CONCLUSIONS

Much has been learned about the different types of bacteria (including commensals) present in the upper respiratory microbiome, but little is known about the virome and mycobiome. A small number of studies have investigated the middle ear microbiome; however, current data are often limited by small sample sizes and methodological heterogeneity between studies. Furthermore, limited reporting of sample collection methods mean that it is often difficult to determine whether bacteria detected in middle ear fluid specimens originated from the middle ear or the external auditory canal. Recent in vitro studies suggest that bacterial interactions in the nasal/nasopharyngeal microbiome may affect otitis media pathogenesis by modifying otopathogen behaviours. Impacts of environmental pressures (e.g. smoke, nutrition) and clinical interventions (e.g. vaccination, antibiotics) on the upper respiratory and middle ear microbiomes remain poorly understood as there are few data.

IMPLICATIONS FOR PRACTICE

Advances in understanding bacterial dynamics in the upper airway microbiome are driving development of microbiota-modifying therapies to prevent or treat disease (e.g. probiotics). Further advances in otitis media microbiomics will likely require technological improvements that overcome the current limitations of OMICs technologies when applied to low volume and low biomass specimens that potentially contain high numbers of host cells. Improved laboratory models are needed to elucidate mechanistic interactions among the upper respiratory and middle ear microbiomes. Minimum reporting standards are critically needed to improve inter-study comparisons and enable future meta-analyses.

Differential IL-17A response to S. pneumoniae in adenoid tissue of children with sleep disordered breathing and otitis media with effusion

Streptococcus pneumonia, one of the major colonizers in nasopharyngeal adenoids, has been the predominant pathogen causing acute otitis media (AOM) in children. Recent evidence suggests an association between IL-17A-mediated immune response and the clearance of pneumococcal colonization in nasopharyngeal adenoids. Here, we evaluated the expressions of IL-17A and associated genes in hypertrophic adenoid tissues of children with sleep-disordered breathing (SDB) and otitis media with effusion (OME) and their association with pneumococcal carriage. Sixty-six pediatric patients with adenoid hypertrophy were enrolled. During adenoidectomy, nasopharyngeal swab and adenoid tissues were used to determine pneumococcal carriage and IL-17A expression. Our results revealed significantly higher levels of IL-17A and IL-17A:IL-10 mRNA in the SDB patients positive for nasopharyngeal pneumococcal carriage than those negative. However, these differences were not significant in the OME group. These results suggested, in OME patients, prolonged or chronic pneumococcal carriage may occur because of insufficient IL-17A-mediated mucosal clearance, and could further lead to AOM and OME development.

Recent Perspectives on Gene-Microbe Interactions Determining Predisposition to Otitis Media

A comprehensive understanding about the pathogenesis of otitis media (OM), one of the most common pediatric diseases, has the potential to alleviate a substantial disease burden across the globe. Advancements in genetic and bioinformatic detection methods, as well as a growing interest in the microbiome, has enhanced the capability of researchers to investigate the interplay between host genes, host microbiome, invading bacteria, and resulting OM susceptibility. Early studies deciphering the role of genetics in OM susceptibility assessed the heritability of the phenotype in twin and triplet studies, followed by linkage studies, candidate gene approaches, and genome-wide association studies that have helped in the identification of specific loci. With the advancements in techniques, various chromosomal regions and genes such as FBXO11, TGIF1, FUT2, FNDC1, and others have been implicated in predisposition to OM, yet questions still remain as to whether these implicated genes truly play a causative role in OM and to what extent. Meanwhile, 16S ribosomal RNA (rRNA) sequencing, microbial quantitative trait loci (mbQTL), and microbial genome-wide association studies (mGWAS) have mapped the microbiome of upper airways sites and therefore helped in enabling a more detailed study of interactions between host polymorphisms and host microbiome composition. Variants of specific genes conferring increased OM susceptibility, such as A2ML1, have also been shown to influence the microbial composition of the outer and middle ear in patients with OM, suggesting their role as mediators of disease. These interactions appear to impact the colonization of known otopathogens (Streptococcus pneumoniae, Haemophilus influenzae, and Moraxella catarrhalis), as well as Neisseria, Gemella, Porphyromonas, Alloprevotella, and Fusobacterium populations that have also been implicated in OM pathogenesis. Meanwhile, studies demonstrating an increased abundance of Dolosigranulum and Corynebacterium in healthy patients compared to those with OM suggest a protective role for these bacteria, thereby introducing potential avenues for future probiotic treatment. Incorporating insights from these genetic, microbiome, and host-pathogen studies will allow for a more robust, comprehensive understanding of OM pathogenesis that can ultimately facilitate in the development of exciting new treatment modalities.

Examining the Evidence for an Adult Healthy Middle Ear Microbiome

Otitis media (OM) is a cluster of diseases of the middle ear that commonly result from bacterial infection. OM subtypes in which the tympanic membrane is intact (acute otitis media and otitis media with effusion) are presumed to result from pathogen translocation through the eustachian tube. Recent molecular-based studies have suggested that a diverse middle ear microbiome exists in the absence of disease. These have been largely unsupported by culture and feature species that commonly contaminate low-biomass sequencing data. Combining culture-based and molecular techniques, we undertook a detailed investigation of the evidence for bacterial colonization of the healthy middle ear. Middle ear (ME), nasopharynx (NP), and external ear canal (EC) swabs were collected from a total of 25 adult patients undergoing cochlear implant, stapedotomy, or translabyrinthine vestibular schwannoma resection. Diagnostic culture, microscopy, quantitative PCR, and 16S rRNA gene amplicon sequencing were used to assess sample bacterial content. EC and NP microbiota were consistent with previous reports. In contrast, bacterial levels in ME samples were not significantly above those in unused control swabs. Commonly detected taxa were among recognized sequencing contaminants (Methylobacterium, Pseudomonas, and Acinetobacter). Linear regression of dominant ME taxa confirmed a negative relationship between relative abundance and bacterial load, consistent with contamination. No bacteria were detected by microscopy or diagnostic culture in any middle ear sample. Our findings cast substantial doubt on previous reports identifying a healthy middle ear microbiome using 16S amplicon sequencing.IMPORTANCE Recent molecular-based studies have suggested that a diverse middle ear microbiome in adults and children can exist in the absence of disease. These studies have been largely unsupported by culture and feature species that commonly contaminate low-biomass sequencing data. While 16S rRNA gene amplicon sequencing has proven to be a highly informative technique in many clinical contexts, it is susceptible to spurious signal arising from sequencing reagent contaminants where sample biomass is low. Combining culture-based and molecular techniques, we undertook a detailed investigation of the evidence for bacterial colonization of the healthy middle ear. In finding no evidence of viable bacterial cells in middle ear samples, our study further underlines the importance of careful consideration of amplicon sequence data derived from very-low-biomass contexts and the value of analytical approaches that combine culture and molecular techniques.