Microbiology of otitis media in Indigenous Australian children: review

Otitis Media in Children with Down Syndrome Is Associated with Shifts in the Nasopharyngeal and Middle Ear Microbiotas

Background: Otitis media (OM) is defined as middle ear (ME) inflammation that is usually due to infection. Globally, OM is a leading cause of hearing loss and is the most frequently diagnosed disease in young children. For OM, pediatric patients with Down syndrome (DS) demonstrate higher incidence rates, greater severity, and poorer outcomes. However, to date, no studies have investigated the bacterial profiles of children with DS and OM. Method: We aimed to determine if there are differences in composition of bacterial profiles or the relative abundance of individual taxa within the ME and nasopharyngeal (NP) microbiotas of pediatric OM patients with DS (n = 11) compared with those without DS (n = 84). We sequenced the 16S rRNA genes and analyzed the sequence data for diversity indices and relative abundance of individual taxa. Results: Individuals with DS demonstrated increased biodiversity in their ME and NP microbiotas. In children with OM, DS was associated with increased biodiversity and higher relative abundance of specific taxa in the ME. Conclusion: Our findings suggest that dysbioses in the NP of DS children contributes to their increased susceptibility to OM compared with controls. These findings suggest that DS influences regulation of the mucosal microbiota and contributes to OM pathology.

Can non‐typeable Haemophilus influenzae carriage surveillance data infer antimicrobial resistance associated with otitis media?

Importance

In remote communities of the Northern Territory, Australia, children experience high rates of otitis media (OM), commonly caused by non-typeable Haemophilus influenzae (NTHi). Few data exist on antibiotic susceptibility of NTHi from OM.

Objective

To determine whether population-level nasopharyngeal NTHi antibiotic susceptibility data could inform antibiotic treatment for OM.

Methods

NTHi isolates (n = 92) collected from ear discharge between 2003 and 2013 were selected to time- and age-match NTHi isolates from the nasopharyngeal carriage (n = 95). Antimicrobial susceptibility were tested. Phylogenomic trees and a genome-wide association study (GWAS) were performed to determine the similarity of nasopharyngeal and ear isolates at a population level.

Results

Among 174 NTHi isolates available for antimicrobial susceptibility testing, 10.3% (18/174) were resistant to ampicillin and 9.2% (16/174) were resistant to trimethoprim-sulfamethoxazole. Small numbers of isolates (≤3) were resistant to tetracycline, chloramphenicol, or amoxicillin-clavulanic acid. There was no statistical difference in the proportion of ampicillin-resistant (P = 0.11) or trimethoprim-sulfamethoxazole-resistant isolates (P = 0.70) between ear discharge and nasopharynx-derived NTHi isolates. Three multi-drug resistant NTHi isolates were identified. Phylogenomic trees showed no clustering of 187 Haemophilus influenzae isolates based on anatomical niche (nasopharynx or ear discharge), and no genetic variations that distinguished NTHi derived from ear discharge and nasopharyngeal carriage were evident in the GWAS.

Interpretation

In this population-level study, nasopharyngeal and ear discharge isolates did not represent distinct microbial populations. These results support tracking of population-level nasopharyngeal NTHi antibiotic resistance patterns to inform clinical management of OM in this population.

The FUT2 Variant c.461G>A (p.Trp154*) Is Associated With Differentially Expressed Genes and Nasopharyngeal Microbiota Shifts in Patients With Otitis Media

Otitis media (OM) is a leading cause of childhood hearing loss. Variants in FUT2, which encodes alpha-(1,2)-fucosyltransferase, were identified to increase susceptibility to OM, potentially through shifts in the middle ear (ME) or nasopharyngeal (NP) microbiotas as mediated by transcriptional changes. Greater knowledge of differences in relative abundance of otopathogens in carriers of pathogenic variants can help determine risk for OM in patients. In order to determine the downstream effects of FUT2 variation, we examined gene expression in relation to carriage of a common pathogenic FUT2 c.461G>A (p.Trp154*) variant using RNA-sequence data from saliva samples from 28 patients with OM. Differential gene expression was also examined in bulk mRNA and single-cell RNA-sequence data from wildtype mouse ME mucosa after inoculation with non-typeable Haemophilus influenzae (NTHi). In addition, microbiotas were profiled from ME and NP samples of 65 OM patients using 16S rRNA gene sequencing. In human carriers of the FUT2 variant, FN1, KMT2D, MUC16 and NBPF20 were downregulated while MTAP was upregulated. Post-infectious expression in the mouse ME recapitulated these transcriptional differences, with the exception of Fn1 upregulation after NTHi-inoculation. In the NP, Candidate Division TM7 was associated with wildtype genotype (FDR-adj-p=0.009). Overall, the FUT2 c.461G>A variant was associated with transcriptional changes in processes related to response to infection and with increased load of potential otopathogens in the ME and decreased commensals in the NP. These findings provide increased understanding of how FUT2 variants influence gene transcription and the mucosal microbiota, and thus contribute to the pathology of OM.

Defining the microbiome of the head and neck: A contemporary review

OBJECTIVE

The purpose of this paper is to define the microbiome of the head and neck by characterizing and distinguishing the commensal bacteria from pathogenic species.

STUDY DESIGN

Literature review.

METHODS

Pubmed and Google scholar databases were queried for relevant articles. Keywords such as "middle ear microbiome", "outer ear microbiome", "sinonasal microbiome", "tonsil microbiome", and "laryngeal microbiome" were utilized separately to identify articles pertaining to each topic of study. All applicable abstracts were chosen for initial review and relevant abstracts were then selected for review of the full texts. Articles that did not study the human microbiome, those not written primarily in English, those that were not readily available for full review, and case reports were excluded from the study.

RESULTS

Limited studies that investigate the microbial environments of isolated anatomic subsites in the head and neck exist, however the comprehensive microbiome of the head and neck has yet to be completely defined. Based on this review, various studies of the ears, larynx, tonsils and sinus microbiomes exist and yield valuable information, however they are limited in scope and anatomic subsite. In this literature review, these studies are compiled in order to create a comprehensive text inclusive of the known microbial elements of the major anatomic subsites of the head and neck, namely the tonsils, larynx, sinus, outer ear and middle ear.

CONCLUSIONS

The significance of the human microbiome in identifying and preventing disease has been established in various physiologic systems, however there is limited research on the microbiome of the head and neck. Understanding the microbiome of the head and neck can help differentiate disease-prone patients from normal patients and guide treatment regimens and antibiotic usage, to aid in resistance control and limit adverse effects of antibiotic overuse. Understanding the elements that lead to dysbiosis can help treat and even prevent common conditions as tonsillitis and rhinosinusitis. In this review, we provide a comprehensive review to serve as an initial background for future studies to define the head and neck microbiome distinguished by all relevant subsites.

Dental tray adhesives and their role as potential transmission medium for microorganisms

Objectives

This study aimed to evaluate the possible ability of dental impression tray adhesives to serve as a transmission medium for bacteria and fungi when reusable adhesive applicators are utilized.

Materials and methods

Ten flasks with tray adhesive were monitored over a period of 12 weeks during clinical use for contamination with bacteria or fungi. Adhesive fluid samples were cultivated on eight different culture media. All grown colonies were identified by using mass spectrometry (MALDI‐TOF). Isolates without reliable identification were either identified by Rapid ID 32 API‐STREP V3.0 or by sequencing the 16S rRNA genes.

Results

After 4 weeks, bacterial growth was detected on chocolate blood agar plates in five different samples. The bacterial species were identified as Staphylococcus warnerii, Staphylococcus epidermidis, Staphylococcus pasteuri, Ralstonia insidiosa, and Alloiococcus otitidis. After 8 weeks Streptococcus oralis grew on a blood agar plate. In all samples, no fungi were identified.

Conclusions

The disinfectant component of the tested tray adhesive seems to be effective. However, some bacteria survived in the flask for a clinically relevant time, which might result in a potential transmission to a new host.

Dichotic listening is associated with phonological awareness in Australian aboriginal children with otitis media: A remote community-based study

OBJECTIVE

Recent literature has highlighted a link between hearing loss as a result of otitis media in the early years of life and impacted binaural processing skills in later childhood. Such findings are of particular relevance to Indigenous Australian children, who tend to experience otitis media earlier in life and for longer periods than their non-Indigenous counterparts. There is also growing interest in the effects of reduced auditory processing ability on a child's early learning of language and, specifically, on phonological awareness that contributes to word reading skills. The aim of the present study was to determine the association between hearing thresholds, dichotic listening skills and phonological awareness in children with pervasive otitis media (OM) from remote Indigenous communities of Australia who generally do not speak English as a first language.

METHODS

Participants included one hundred and one children between the ages of 4.8-7.9 years (mean 6.1 years) from three separate remote Northern Territory communities. Evaluations included otoscopy, air conduction PTA, and tympanometry. All children were also assessed on the Dichotic Digits difference test (DDdT) and the Foundations of Early Literacy Assessment (FELA), assessing children's dichotic listening and phonological awareness respectively.

RESULTS

The results showed that 56% of the children had middle ear dysfunctions (type B and type C on tympanometry results) in at least one ear on the day. Partial correlation showed a significant correlation, between dichotic scores and FELA with age as covariate (r = 0.45, p < 0.001). One way ANOVA showed females exhibited a significantly higher performance compared to males on FELA [F (1, 99) = 5.47, p = 0.021]. The overall regression model was found to be significant in predicting total FELA scores [F (7, 77) = 7.56, p < 0.0005]. Age and gender as well as dichotic listening scores explain 40.7% of the variance.

CONCLUSIONS

The results reinforce the importance of managing the ear health of Indigenous children, clarifying the impact this has on listening and phonological awareness. These findings highlight the importance of evaluating children's listening abilities, and how poor listening can impact phonological awareness. The findings have important implications for ensuring optimal listening and learning conditions in schools in remote NT communities.

Niche- and Gender-Dependent Immune Reactions in Relation to the Microbiota Profile in Pediatric Patients with Otitis Media with Effusion

Otitis media with effusion (OME) is a common inflammatory disease that primarily affects children. OME is defined as a chronic low-grade inflammation of the middle ear (ME), without any signs of infection and with effusion persisting in the ME for more than 3 months. The precise pathogenesis is, however, not fully understood. Here, we comprehensively characterized and compared the host immune responses (inflammatory cells and mediators) and the overall microbial community composition (microbiota) present in matched middle ear effusion (MEE) samples, external ear canal (EEC) lavages, and nasopharynx (NPH) samples from children with OME.

Otitis media with effusion (OME) is a common inflammatory disease that primarily affects children. OME is defined as a chronic low-grade inflammation of the middle ear (ME), without any signs of infection and with effusion persisting in the ME for more than 3 months. The precise pathogenesis is, however, not fully understood. Here, we comprehensively characterized and compared the host immune responses (inflammatory cells and mediators) and the overall microbial community composition (microbiota) present in matched middle ear effusion (MEE) samples, external ear canal (EEC) lavages, and nasopharynx (NPH) samples from children with OME. Female patients had significantly increased percentages of T lymphocytes and higher levels of a wide array of inflammatory mediators in their MEE compared to that of male patients, which were unrelated to microbiota composition. The relative abundances of identified microorganisms were strongly associated with their niche of origin. Furthermore, specific inflammatory mediators were highly correlated with certain bacterial species. Interestingly, some organisms displayed a niche-driven inflammation pattern in which presence of Haemophilus spp. and Corynebacterium propinquum in MEE was accompanied by proinflammatory mediators, whereas their presence in NPH was accompanied by anti-inflammatory mediators. For Turicella and Alloiococcus, we found exactly the opposite results, i.e., an anti-inflammatory profile when present in MEE, whereas their presence in the the NPH was accompanied by a proinflammatory profile. Together, our results indicate that immune responses in children with OME are highly niche- and microbiota-driven, but gender-based differences were also observed, providing novel insight into potential pathogenic mechanisms behind OME.

Panel 6: Otitis media and associated hearing loss among disadvantaged populations and low to middle-income countries

OBJECTIVE:

Summarise the published evidence on otitis media and associated hearing loss in low to middle-income countries (LMIC) and disadvantaged populations.

DATA SOURCES:

PubMed and other databases.

REVIEW METHODS:

Firstly, sensitive search strategy using ‘otitis media’, combined with specific key words for each topic of the review, from January 2015 to June 2019. Then, restriction to LMIC and disadvantaged populations. Topics covered included prevention, epidemiology, risk factors, microbiology, prognosis, diagnosis, and treatment.

CONCLUSIONS:

There was a high degree of methodological heterogeneity and high risk of bias. The majority of studies were school-based. In Africa, Asia and Oceania (e.g., Australian Aboriginal populations) the prevalence of OM was respectively 8% (range 3–16%), 14% (range 7–22%) and 50% (4–95%). Prevalence of any hearing loss in these regions was 12% (range 8–17%), 12% (range 3–24%), and 26% (range 25–28%) respectively. Risk factors in LMIC and disadvantaged populations included age, gender, exposure to smoke and pollution. Microbiology was reported for otitis media with effusion at time of surgery or ear discharge (acute otitis media with perforation or chronic suppurative otitis media). Specimen handling and processing in hospital laboratories was associated with low detection of S. pneumoniae and H. influenzae. Case series described complicated cases of OM due to M. tuberculosis, multidrug resistance and HIV. QOL studies identified discrimination of persons with OM and hearing loss. Diagnostic methods varied greatly, from naked eye to tympanometry. Treatment interventions were reported from four RCTs. Non-RCTs included evaluations of guidelines, surgery outcomes, access to ENTs.

IMPLICATIONS FOR CLINICAL PRACTICE:

Chronic suppurative otitis media, otitis media with effusion and conductive hearing loss are common in LMIC and disadvantaged populations. Paucity of research, poor regional representation, non-standardised methods and low-quality reporting preclude accurate assessment of disease burden in LMIC and disadvantaged populations. Awareness and adherence to reporting Guidelines should be promoted.

Panel 7 - Pathogenesis of otitis media - a review of the literature between 2015 and 2019

OBJECTIVE

To perform a comprehensive review of the literature from July 2015 to June 2019 on the pathogenesis of otitis media. Bacteria, viruses and the role of the microbiome as well as the host response are discussed. Directions for future research are also suggested.

DATA SOURCES

PubMed database of the National Library of Medicine.

REVIEW METHODS

PubMed was searched for any papers pertaining to OM pathogenesis between July 2015 and June 2019. If in English, abstracts were assessed individually for their relevance and included in the report. Members of the panel drafted the report based on these searches and on new data presented at the 20th International Symposium on Recent Advances in Otitis Media.

CONCLUSIONS

The main themes that arose in OM pathogenesis were around the need for symptomatic viral infections to develop disease. Different populations potentially having different mechanisms of pathogenesis. Novel bacterial otopathogens are emerging and need to be monitored. Animal models need to continue to be developed and used to understand disease pathogenesis.

IMPLICATIONS FOR PRACTICE

The findings in the pathogenesis panel have several implications for both research and clinical practice. The most urgent areas appear to be to continue monitoring the emergence of novel otopathogens, and the need to develop prevention and preventative therapies that do not rely on antibiotics and protect against the development of the initial OM episode.

Unnecessary prescribing of antibiotics to healthy/asymptomatic school-age carriers of potentially pathogenic bacteria

OBJECTIVES

To re-draw attention to the unnecessary prescribing of antibiotics.

METHODS

We monitored nasopharyngeal colonization by 3 potentially pathogenic bacteria, Streptococcus pyogenes, Streptococcus pneumoniae, and Haemophilus influenzae type b in 81 children between the ages of 6 and 7 years who attended the same primary school. The children's health status was also monitored, without using antimicrobial treatment for healthy/asymptomatic carriers. Nasopharyngeal swabs were collected on 6 occasions during autumn months, from mid-September to mid-December 2016. The children who fell ill during the study were treated at the Ear, Nose and Throat Clinic, Sisters of Mercy University Hospital Center, Zagreb, Croatia.

RESULTS

Four hundred and sixty-three  nasopharyngeal swabs were collected. Each child had at least one positive swab result. Bacterial colonization with Streptococcus pyogenes had the highest colonization rate. During the study, 83% of the children were healthy/asymptomatic carriers with no clinical signs of disease,  while 17% became ill. The statistical results showed that the increase in all examined bacteria was statistically significant.

CONCLUSIONS

  Our  study results showed that positive bacterial findings in nasopharyngeal swabs from clinically healthy carriers were not an indication for antibiotic therapy.

Does access to saltwater swimming pools reduce ear pathology and hearing loss in school children of remote arid zone aboriginal communities? A prospective 3-year cohort study

OBJECTIVE

To assess whether access to saltwater chlorinated swimming pools in remote Aboriginal communities is beneficial in reducing levels of middle ear disease and hearing loss in school children.

DESIGN

A prospective 3-year cohort study of children in 10 remote Aboriginal communities in South Australia with (n = 4) or without (n = 6) swimming pools.

SETTING

Outback Australia.

PARTICIPANTS

Eight hundred and thirteen school-age children residing in remote South Australia.

MAIN OUTCOME MEASURES

Prevalence of open and closed middle ear disease and prevalence of hearing loss.

RESULTS

About 2107 ear assessments were conducted during the study period. 70.7% of children in communities with pools failed a screening test of hearing compared with 68.6% of children in non-pool communities (P = 0.637). 32.3% of children had chronic otitis media (COM). There was no difference between pool and non-pool communities in the frequency of either inactive (19.4% pool vs 22.6% non-pool; P = 0.232) or active (19.8% pool vs 17.8% non-pool; P = 0.383) COM. In children with bilateral intact tympanic membranes, 21.2% had unilateral and 20.6 had bilateral type B tympanograms. There was no difference between pool and non-pool communities in the frequency of type B tympanometry (P = 0.465).

CONCLUSIONS

Hearing loss associated with both open and closed middle ear disease remains highly prevalent in children living in remote Aboriginal communities in South Australia. Access to swimming pools in this population does not appear to significantly reduce these high levels of middle ear disease or associated hearing loss.

Risk factors for persistent otitis media with effusion in children: a case-control study

Background

Otitis media with effusion (OME) is defined as middle ear effusion without acute signs of infection. OME usually resolves spontaneously; however, persistent OME may require the insertion of a ventilation tube. This study investigated risk factors for persistent OME in children who undergo ventilation tube insertion.

Methods

Children who were admitted to undergo ventilation tube insertion at Jeju National University Hospital between August 2015 and July 2016 were enrolled as the case group. Healthy children without persistent OME from August 2016 to July 2017 were enrolled as the control group. Baseline characteristics and predisposing factor data were collected using an interview questionnaire. Middle ear fluids were collected from the case group.

Results

A total of 31 patients underwent ventilation tube insertion. The mean age of the case group was 4.53 years, with a male-to-female ratio of 21:10. Twenty-nine (93.5%) children attended a daycare center, and 21 (67.7%) had experience with bottle feeding. Fifteen (48.4%) children in the case group and 3 (9.7%) in the control group first attended a daycare center at <1 year of age (odds ratio=9.96; 95% confidence interval=2.44-39.70; p=0.001). No bacteria were found in middle ear fluid collected from the 31 operated children. Nasopharyngeal bacterial colonization was found in 13 (41.9%) and 17 (54.8%) children in the case and control groups, respectively.

Conclusion

Earlier attendance at a daycare center was the only predisposing factor for ventilation tube insertion in our study. The aseptic nature of middle ear fluids found in children with OME highlights the efficacy of antimicrobial use.

Characterization of the nasopharyngeal and middle ear microbiota in gastroesophageal reflux-prone versus gastroesophageal reflux non-prone children

Otitis media (OM) is one of the most common pediatric infections worldwide, but the complex microbiology associated with OM is poorly understood. Previous studies have shown an association between OM and gastroesophageal reflux (GER) in children. Therefore, in order to bridge the gap in our current understanding of the interaction between GER and OM, we investigated the nasopharyngeal and middle ear microbiota of children suffering from GER-associated OM and OM only, using culture-independent 16S rRNA gene sequencing. Middle ear fluid, nasopharyngeal swabs, and clinical data were collected as part of a prospective pilot study conducted at the Department of Otorhinolaryngology of the Erasmus MC-Sophia Children's Hospital, Rotterdam, the Netherlands. A total of 30 children up to 12 years of age who suffered from recurrent acute otitis media (AOM) (5), chronic otitis media with effusion (OME) (23), or both (2), and who were listed for tympanostomy tube placement, were included in the study. Nine children were included in the GER-associated OM cohort and 21 in the OM-only cohort. We found no obvious effect of GER on the nasopharyngeal and middle ear microbiota between the two groups of children. However, our results highlight the need to assess the true role of Alloiococcus spp. and Turicella spp. in children presenting with a high prevalence of recurrent AOM and chronic OME.