How does endotoxin trigger inflammation in otitis media with effusion?

The Prevalence and Association of Biofilms With Otitis Media With Effusion: A Systematic Review and Meta-Analysis

PURPOSE

We aimed to identify the role of bacterial biofilms in the chronicity of otitis media with effusion and its resistance to antibiotics. We illustrated this role by reviewing, analyzing, and correlating the findings with the results of the included studies to reach clear evidence.

METHODS

A comprehensive search of electronic databases (Scopus, PubMed, Web of Science, Cochrane, and GHL databases) was performed for all studies using the following strategy till April 2021 with the search terms: Biofilm and Middle ear effusion. We found 935 references, 421 were duplicates, and 514 were needed for further screening, and it was as follows: PubMed 215, Scopus 18, Cochrane 130, Web of Science 136, and GHL 15.

RESULTS

The pooled prevalence of culture-positive effusions was estimated to be 40% (95% CI [28%, 53%]) of the total OME population. Overall, the prevalence of PCR-positive effusions was estimated to be 97% (95% CI [95%, 99%]) of the total OME population. The pooled prevalence of EM-positive effusions was estimated to be 82% (95% CI [69%, 95%]) of the total OME population.

CONCLUSION

The data presented in this study coincide with the significant role of bacterial biofilms in the pathogenesis of chronic otitis media with effusion. The involvement of bacterial biofilm as a component of the OME pathogenic process can help us to explain why antimicrobial therapy is not always effective in the eradication of the disease process and, also explain the recurrence of middle ear effusion after treatment with tympanostomy tubes either with or without adenoidectomy.

An Organ System-Based Synopsis of Pseudomonas aeruginosa Virulence

Driven in part by its metabolic versatility, high intrinsic antibiotic resistance, and a large repertoire of virulence factors, Pseudomonas aeruginosa is expertly adapted to thrive in a wide variety of environments, and in the process, making it a notorious opportunistic pathogen. Apart from the extensively studied chronic infection in the lungs of people with cystic fibrosis (CF), P. aeruginosa also causes multiple serious infections encompassing essentially all organs of the human body, among others, lung infection in patients with chronic obstructive pulmonary disease, primary ciliary dyskinesia and ventilator-associated pneumonia; bacteremia and sepsis; soft tissue infection in burns, open wounds and postsurgery patients; urinary tract infection; diabetic foot ulcers; chronic suppurative otitis media and otitis externa; and keratitis associated with extended contact lens use. Although well characterized in the context of CF, pathogenic processes mediated by various P. aeruginosa virulence factors in other organ systems remain poorly understood. In this review, we use an organ system-based approach to provide a synopsis of disease mechanisms exerted by P. aeruginosa virulence determinants that contribute to its success as a versatile pathogen.

Otitis media with effusion is not a sterile inflammatory process: scanning electron microscope evidence

PURPOSE

We aimed to demonstrate whether chronic otitis media with effusion (OME) is a sterile condition or biofilms-related disease through direct visualization of middle ear mucosa by Scanning electron microscopy (SEM) and culture of the effusion.

METHODS

This case-control study included 60 children in two groups; the case group included 50 patients undergoing ventilation tube insertion (VTI) for Chronic OME (COME), and the control group included ten patients undergoing cochlear implantation (CI) surgery presenting normal middle ear mucosa. Biopsies from both groups' middle ear mucosa were evaluated for biofilm formation using scanning electron microscopy (SEM). Middle ear effusion (MEE) samples from COME patients were cultured on blood agar to detect and identify any bacterial growth. The adenoid size was evaluated and correlated to the biofilm formation in COME patients.

RESULTS

There was a significant difference between case and control groups regarding biofilm formation (p-value < 0.001*). Biofilm was evident in 84% of the COME patients (cases group) and absent in the control group. Only 12 COME patients (24%) had positive MEE culture, however, 76.2% of patients with biofilm had a negative culture. Streptococcus pneumonia was the most common otopathogen found either alone or combined with other otopathogens. There was a significant negative correlation between adenoid size and biofilm grade among the studied patients.

CONCLUSION

The visual identification of middle ear biofilms indicated their role in chronic OME. Middle ear biofilms need to be expected in children with OME, especially those who do not need adenoid surgery.

Nitrotyrosine in Otitis Media with Effusion

Objectives:

Our purpose was to investigate mucosal cell injury due to the nitric oxide (NO)-superoxide system in otitis media with effusion.

Methods:

We determined the levels of nitrotyrosine (NT) and NO and the activities of superoxide dismutase (SOD) and lactic dehydrogenase (LDH) in 90 middle ear fluid samples.

Results:

The NT concentration was significantly higher in group A (<16 years old) than in group C (>50 years old; p <.05), and significantly higher in the acute group than in the chronic group (p <.05). The NO concentration did not show a significant difference among the groups. The activity of SOD showed significant correlations with the concentrations of NT and NO and with LDH activity (p <.05). The LDH activity was significantly greater in group A than in group C (p <.05).

Conclusions:

Our results indicate involvement of the NO-superoxide system in the pathogenesis of otitis media with effusion, showing evidence of protein and/or cell injury in the middle ear.

Oral use of Streptococcus salivarius K12 in children with secretory otitis media: preliminary results of a pilot, uncontrolled study

Secretory otitis media (SOM) remains a common disease among children. Although its cause is not yet perfectly established, the pathology, often a sequel of acute otitis media (AOM), is mainly characterized by persistent fluid in the middle ear cavity. Twenty-two children with a diagnosis of SOM were treated daily for 90 days with an oral formulation containing the oral probiotic Streptococcus salivarius K12 (Bactoblis^®). After treatment, the children were evaluated for AOM episodes and subjected to tone audiometry, tympanometry, endonasal endoscopy, otoscopy, and tonsillar examination. Subject compliance and probiotic tolerability and side effects have also been evaluated. Our results indicate a good safety profile, a substantial reduction of AOM episodes, and a positive outcome from the treatment for all of the clinical outcomes tested. We conclude that strain K12 may have a role in reducing the occurrence and/or severity of SOM in children. From our perspective, this study constitutes a starting point toward the organization of a more extensive placebo-controlled study aimed at critically appraising our preliminary observations.

Substance P and vasoactive intestinal peptide levels in middle ear effusions of children

CONCLUSION

This is the first report demonstrating high levels of substance P (SP) that inversely correlate with vasoactive intestinal peptide (VIP) levels in middle ear effusions (MEEs) of patients with otitis media with effusion (OME). Increased SP and decreased VIP levels might play a role in the pathogenesis of chronic OME.

OBJECTIVE

The etiology of OME is multifactorial, and neurogenic inflammation may play a significant role. SP and VIP levels were not evaluated previously in MEEs of children with OME.

METHODS

Fifty patients aged 2-12 years (mean age 5.24 ± 2.64) were included in the study. MEEs were classified as mucoid or serous based on the gross appearance. SP and VIP levels were determined using ELISA.

RESULTS

High levels of SP were detected in MEEs. In addition SP levels were significantly higher in serous samples (2910.55 ± 307.96 vs 2218.55 ± 262.30 pg/ml). There were also age-dependent changes, such that SP levels were significantly higher in children aged 2-3 years compared with those who were 4-5 and 6-12 years old. VIP levels were undetectable in 30% of patients and the mean level of VIP was 50.91 ± 16.01 pg/ml in serous middle ear effusions and 54.86 ± 15.91 pg/ml in mucoid MEEs.

Bacterial involvement in otitis media with effusion

OBJECTIVE

Otitis media with effusion (OME), a common chronic childhood condition affecting hearing, is thought to be a result of bacterial infection, with biofilms recently implicated. Although bacterial DNA can be detected by polymerase chain reaction in 80% of patients, typically fewer than half of effusions are positive using standard culture techniques. We adopted an alternative approach to demonstrating bacteria in OME, using a bacterial viability stain and confocal laser scanning microscopy (CLSM): staining allows detection of live bacteria without requiring growth on culture, while CLSM allows demonstration of the three-dimensional structure typical of biofilms.

METHODS

Effusion samples were collected at the time of ventilation tube insertion, analysed with CLSM and bacterial viability stain, and extended culture techniques performed with the intention of capturing all possible organisms.

RESULTS

Sixty-two effusions (42 patients) were analysed: 28 (45.2%) were culture-positive, but 51 (82.3%) were CLSM-positive. Combining the two techniques demonstrated live bacteria in 57 (91.8%) samples. Using CLSM, bacteria exhibited biofilm morphology in 25 effusions and were planktonic in 26; the proportion of samples exhibiting biofilm morphology was similar in the culture-positive and culture-negative groups (50.0% and 48.3%, respectively). Biofilm samples contained an average of 1.7 different bacterial isolates and planktonic samples 2.0, with the commonest bacteria identified being coagulase-negative staphylococci.

CONCLUSION

Live bacteria are present in most effusions, strongly suggesting that bacteria and biofilms are important in the aetiopathogenesis of OME.

Otitis Media: A Review, with a Focus on Alternative Treatments

Otitis media (OM) is the accumulation of fluids in the middle ear, with or without symptoms of inflammation. The infection is caused by dysfunction or obstruction of the eustachian tube and is most commonly diagnosed in children under the age of two. The microbiology of OM differs, with Streptococcus pneumoniae, non-typeable Haemophilus influenzae and Moraxella catarrhalis the most commonly isolated pathogens. The emergence of penicillin-resistant Strep. pneumoniae, β-lactamase-producing strains, Haem. influenzae and Mor. catarrhalis is a major concern and health care costs associated with treatment are substantial, especially in cases of unresponsive treatment as a result of incorrect diagnosis. Alternative treatments such as vaccines and a nasal spray containing α-haemolytic streptococci with antimicrobial activity against OM pathogens, have been developed. The rationale behind such treatments is to induce an appropriate immune response against the pathogens and decrease bacterial colonisation in the nasopharynx. Another approach may be treatment with bacteriocins (natural antimicrobial peptides) or bacteriocin-like inhibitory substances (BLIS) produced by lactic acid bacteria. We have recently described an antibacterial peptide produced by Enterococcus mundtii ST4SA and have published on bacteriocins (enterocins) with antibacterial and antiviral activity. This review discusses the condition OM, summarises current methods used to treat the infection, and suggests alternative safe and natural treatments that need to be explored.

Proinflammatory and immunoregulatory cytokines in the middle ear effusions

OBJECTIVE

The recognition of inflammatory mediators in middle ear effusions and their correlation with clinical parameters may allow better understanding of many complex events leading to development of permanent sequelae of otitis media and hopefully help to develop future interventions. The aim of the study was to evaluate the presence and level of proinflammatory interleukin (IL) 1beta, IL-6 and immunoregulatory IL-10 in the middle ear effusions, their mutual correlation and relationship with age, duration of the illness, number of episodes of acute otitis media, and presence of retraction pockets.

METHODS

The study included 25 children (41 ears), who had been scheduled for myringotomy with the insertion of tympanostomy tubes due to otitis media with effusion. The interview (duration of the illness, number of episodes of acute otitis media), clinical and audiological examination was conducted according to the developed examination check list. Middle ear effusions (MEE) were collected aseptically, the samples centrifuged and supernatant frozen at a temperature of -80 degrees C. The IL-1beta, IL-6 and IL-10 were assayed using enzyme-linked immunosorbent assay (ELISA) kits incorporating monoclonal antibodies and the ETI system reader. The nonparametric Mann-Whitney U test was used for statistical analysis and Pearson's linear correlation coefficient was calculated.

RESULTS

IL-1beta was detected in 80% of examined effusions, IL-6 in 78%, and IL-10 in 88%. There was a strong statistical correlation between IL-1beta and IL-6 concentrations (r=0.627, P=0.000), as well as IL-6 and IL-10 (r=0.66, P=0.000) No statistically significant correlation was found between levels of cytokines and clinical parameters.

CONCLUSIONS

Proinflammatory and immunoregulatory cytokines participate in middle ear inflammatory response. The lack of direct correlation between IL-1beta and IL-10 may be responsible for chronic character of the disease. As no correlation between the levels of cytokines and clinical parameters was found it seems that the time of duration of inflammation rather than its intensity measured by levels of cytokines is the main factor in development of middle ear mucosa pathology.

Effect of myringotomy on prognosis in pediatric acute otitis media

OBJECTIVE

In children with acute otitis media (AOM), we compared clinical outcomes between groups with and without myringotomy to elucidate the effect of this procedure on long-term clinical course and prognosis.

METHODS

Fifty-nine children (29 male, 30 female) with tympanic membrane bulging or middle ear fluid (MEF) at initial presentation were assigned to one of two treatment groups. Group A received oral antibiotics and also underwent myringotomy at initial enrollment (36 cases), while group B received oral antibiotics without myringotomy (23 cases). Clinical outcomes were evaluated by otolaryngologic specialists using pneumatic otoscopy and tympanometry at 5, 10, 15, 30 days and 12 weeks and then every 2 weeks after the initial treatment. Otitis media with effusion (OME), early recurrence and recurrent AOM were used as the evaluation criteria for the prognosis.

RESULTS

In group A, 6 children (16.7%) showed transition to OME, 11 (30.6%) showed early recurrence of AOM, and 9 (25.0%) developed recurrent AOM. In group B 10, 8, and 3 (43.5%, 34.8%, and 13.0%) showed these respective adverse outcomes. While early recurrence rates and recurrent AOM rates did not differ significantly between groups, progression of OME was significantly less frequent in group A than group B (P = 0.036).

CONCLUSIONS

Lower rates of progression to OME in the group undergoing myringotomy suggested that myringotomy might be effective in preventing this outcome.

Cell adhesion molecules and cytokines in middle ear effusions in children with or without recent acute otitis media

OBJECTIVES

We sought to compare the levels of cytokines and cell adhesion molecules in middle ear effusions (MEEs) of children with (group 1) or without (group 2) acute otitis media (AOM) within 3 months of obtaining MEE and to correlate these levels with hearing loss.

DESIGN AND SUBJECTS

MEE were collected from children (49 and 51 children composed groups 1 and 2, respectively) with otitis media with effusion (OME) undergoing tube placement who had an audiogram performed preoperatively. MEE was assessed as serous or mucoid. Cytokines and cell adhesion molecules were measured by enzyme-linked immunosorbent assay. Data were analyzed with the Student t test, chi(2) test, and the Pearson correlation test.

RESULTS

Concentrations of interleukin (IL)-1, IL-6, and vascular cell adhesion molecules (VCAM) were greater in the MEE of the children in group 1 compared with those of group 2 children. (P < 0.001 for IL-1 and IL-6; P < 0.05 for VCAM). The concentrations of IL-1, IL-6, VCAM, and E-selectin were greater in serous than in mucoid MEE. (P < 0.05). Concentrations of IL-6 correlated with the concentrations of the other 2 cytokines and the 3 cell adhesion molecules. Only concentrations of IL-6 in MEE correlated with the degree of hearing loss (P < 0.002).

CONCLUSIONS

The inflammatory response leading to OME involves multiple cytokines regardless of an AOM episode in the 3 months before obtaining MEE. IL-6 is an important cytokine in the pathogenesis of OME.

The Use of Probiotics in Head and Neck Infections

Recurrent episodes of infections in the upper respiratory tract are very common. The pathogenesis behind these recurrences is still not well understood, but much attention has been paid to the adherence of the microorganisms to epithelial structures and to the protective function of the normal bacterial flora (bacterial interference). Thus, in vitro as well as in vivo studies have shown that both aerobic and anaerobic bacteria of the normal flora in the upper respiratory tract can hinder the growth of pathogens and the establishment of a renewed infection. Studies have shown that lack of interfering bacteria facilitates recurrence of these diseases. Recolonization with interfering alpha-streptococci has been performed successfully in acute streptococcal pharyngotonsillitis, as well as in acute otitis media. The number of recurrences has significantly been lowered in these diseases after recolonization with alpha-streptococci, which is the dominating normal bacteria in the upper respiratory tract. Several mechanisms have been proposed to be responsible for this interaction, such as competition of the adhering sites at the epithelial cells, production of hydrogen peroxide, competition for nutritients, and production of specific growth inhibiting factors such as bacteriocins. Other human components like lactoferrin are also important in the defense against microorganisms, and are important parts of the unspecific and specific immune system.