Direct detection of bacterial biofilms on the middle-ear mucosa of children with chronic otitis media

Artificial Intelligence-Driven Analysis of Antimicrobial-Resistant and Biofilm-Forming Pathogens on Biotic and Abiotic Surfaces

The growing threat of antimicrobial-resistant (AMR) pathogens to human health worldwide emphasizes the need for more effective infection control strategies. Bacterial and fungal biofilms pose a major challenge in treating AMR pathogen infections. Biofilms are formed by pathogenic microbes encased in extracellular polymeric substances to confer protection from antimicrobials and the host immune system. Biofilms also promote the growth of antibiotic-resistant mutants and latent persister cells and thus complicate therapeutic approaches. Biofilms are ubiquitous and cause serious health risks due to their ability to colonize various surfaces, including human tissues, medical devices, and food-processing equipment. Detection and characterization of biofilms are crucial for prompt intervention and infection control. To this end, traditional approaches are often effective, yet they fail to identify the microbial species inside biofilms. Recent advances in artificial intelligence (AI) have provided new avenues to improve biofilm identification. Machine-learning algorithms and image-processing techniques have shown promise for the accurate and efficient detection of biofilm-forming microorganisms on biotic and abiotic surfaces. These advancements have the potential to transform biofilm research and clinical practice by allowing faster diagnosis and more tailored therapy. This comprehensive review focuses on the application of AI techniques for the identification of biofilm-forming pathogens in various industries, including healthcare, food safety, and agriculture. The review discusses the existing approaches, challenges, and potential applications of AI in biofilm research, with a particular focus on the role of AI in improving diagnostic capacities and guiding preventative actions. The synthesis of the current knowledge and future directions, as described in this review, will guide future research and development efforts in combating biofilm-associated infections.

Phage therapy for bone and joint infections: A comprehensive exploration of challenges, dynamics, and therapeutic prospects

OBJECTIVES

Bone and joint infections (BJI) pose formidable challenges in orthopaedics due to antibiotic resistance and the complexities of biofilm, complicating treatment. This comprehensive exploration addresses the intricate challenges posed by BJI and highlights the significant role of phage therapy as a non-antibiotic strategy.

METHODS

BJI, which encompass prosthetic joint infections, osteomyelitis, and purulent arthritis, are exacerbated by biofilm formation on bone and implant surfaces, hindering treatment efficacy. Gram-negative bacterial infections, characterized by elevated antibiotic resistance, further contribute to the clinical challenge. Amidst this therapeutic challenge, phage therapy emerges as a potential strategy, showing unique characteristics such as strict host specificity and biofilm disruption capabilities.

RESULTS

The review unveils the dynamics of phages, including their origins, lifecycle outcomes, and genomic characteristics. Animal studies, in vitro investigations, and clinical research provide compelling evidence of the efficacy of phages in treating Staphylococcus aureus infections, particularly in osteomyelitis cases. Phage lysins exhibit biofilm-disrupting capabilities, offering a meaningful method for addressing BJI. Recent statistical analyses reveal high clinical relief rates and a favourable safety profile for phage therapy.

CONCLUSIONS

Despite its promise, phage therapy encounters limitations, including a narrow host range and potential immunogenicity. The comprehensive analysis navigates these challenges and charts the future of phage therapy, emphasizing standardization, pharmacokinetics, and global collaboration. Anticipated strides in phage engineering and combination therapy hold promise for combating antibiotic-resistant BJI.

The therapeutic use of exosomes in children with adenoid hypertrophy accompanied by otitis media with effusion (AHOME): a protocol study

BACKGROUND

The adenoids act as a reservoir of bacterial pathogens and immune molecules, and they are significantly involved in children with otitis media with effusion (OME). As an essential carrier of intercellular substance transfer and signal transduction, exosomes with different biological functions can be secreted by various types of cells. There remains significant uncertainty regarding the clinical relevance of exosomes to OME, especially in its pathophysiologic development. In this study, we will seek to determine the biological functions of exosomes in children with adenoid hypertrophy accompanied by OME (AHOME).

METHODS

The diagnostic criteria for OME in children aged 4-10 years include a disease duration of at least 3 months, type B or C acoustic immittance, and varying degrees of conductive hearing loss. Adenoidal hypertrophy is diagnosed when nasal endoscopy shows at least 60% adenoidal occlusion in the nostrils or when nasopharyngeal lateral X-ray shows A/N > 0.6. Children who meet the indications for adenoidectomy surgery undergo adenoidectomy. Peripheral blood, nasopharyngeal swab, and adenoid tissue will be collected from patients, and the exosomes will be isolated from the samples. Following the initial collection, patients will undergo adenoidectomy and peripheral blood and nasopharyngeal swabs will be collected again after 3 months.

EXPECTED RESULTS

This study aims to identify differences in exosomes from preoperative adenoid tissue and peripheral blood samples between children with AHOME and those with adenoid hypertrophy alone. Additionally, it seeks to determine changes in microbial diversity in adenoid tissue between these groups.

CONCLUSIONS

The findings are expected to provide new insights into the diagnosis and treatment of OME, to identify novel biomarkers, and to enhance our understanding of the pathophysiology of OME, potentially leading to the development of innovative diagnostic and therapeutic approaches.

Biofilm-dispersed pneumococci induce elevated leukocyte and platelet activation

Introduction

Streptococcus pneumoniae (the pneumococcus) effectively colonizes the human nasopharynx, but can migrate to other host sites, causing infections such as pneumonia and sepsis. Previous studies indicate that pneumococci grown as biofilms have phenotypes of bacteria associated with colonization whereas bacteria released from biofilms in response to changes in the local environment (i.e., dispersed bacteria) represent populations with phenotypes associated with disease. How these niche-adapted populations interact with immune cells upon reaching the vascular compartment has not previously been studied. Here, we investigated neutrophil, monocyte, and platelet activation using ex vivo stimulation of whole blood and platelet-rich plasma with pneumococcal populations representing distinct stages of the infectious process (biofilm bacteria and dispersed bacteria) as well as conventional broth-grown culture (planktonic bacteria).

Methods

Flow cytometry and ELISA were used to assess surface and soluble activation markers for neutrophil and monocyte activation, platelet-neutrophil complex and platelet-monocyte complex formation, and platelet activation and responsiveness.

Results

Overall, we found that biofilm-derived bacteria (biofilm bacteria and dispersed bacteria) induced significant activation of neutrophils, monocytes, and platelets. In contrast, little to no activation was induced by planktonic bacteria. Platelets remained functional after stimulation with bacterial populations and the degree of responsiveness was inversely related to initial activation. Bacterial association with immune cells followed a similar pattern as activation.

Discussion

Differences in activation of and association with immune cells by biofilm-derived populations could be an important consideration for other pathogens that have a biofilm state. Gaining insight into how these bacterial populations interact with the host immune response may reveal immunomodulatory targets to interfere with disease development.

Beyond antibiotics: CRISPR/Cas9 triumph over biofilm-associated antibiotic resistance infections

A complex structure known as a biofilm is formed when a variety of bacterial colonies or a single type of cell in a group sticks to a surface. The extracellular polymeric compounds that encase these cells, often consisting of proteins, eDNA, and polysaccharides, exhibit strong antibiotic resistance. Concerns about biofilm in the pharmaceutical industry, public health, and medical fields have sparked a lot of interest, as antibiotic resistance is a unique capacity exhibited by these biofilm-producing bacteria, which increases morbidity and death. Biofilm formation is a complicated process that is controlled by several variables. Insights into the processes to target for the therapy have been gained from multiple attempts to dissect the biofilm formation process. Targeting pathogens within a biofilm is profitable because the bacterial pathogens become considerably more resistant to drugs in the biofilm state. Although biofilm-mediated infections can be lessened using the currently available medications, there has been a lot of focus on the development of new approaches, such as bioinformatics tools, for both treating and preventing the production of biofilms. Technologies such as transcriptomics, metabolomics, nanotherapeutics and proteomics are also used to develop novel anti-biofilm agents. These techniques help to identify small compounds that can be used to inhibit important biofilm regulators. The field of appropriate control strategies to avoid biofilm formation is expanding quickly because of this spurred study. As a result, the current article addresses our current knowledge of how biofilms form, the mechanisms by which bacteria in biofilms resist antibiotics, and cutting-edge treatment approaches for infections caused by biofilms. Furthermore, we have showcased current ongoing research utilizing the CRISPR/Cas9 gene editing system to combat bacterial biofilm infections, particularly those brought on by lethal drug-resistant pathogens, concluded the article with a novel hypothesis and aspirations, and acknowledged certain limitations.

Biological puzzles solved by using Streptococcus pneumoniae: a historical review of the pneumococcal studies that have impacted medicine and shaped molecular bacteriology

The major human pathogen Streptococcus pneumoniae has been the subject of intensive clinical and basic scientific study for over 140 years. In multiple instances, these efforts have resulted in major breakthroughs in our understanding of basic biological principles as well as fundamental tenets of bacterial pathogenesis, immunology, vaccinology, and genetics. Discoveries made with S. pneumoniae have led to multiple major public health victories that have saved the lives of millions. Studies on S. pneumoniae continue today, where this bacterium is being used to dissect the impact of the host on disease processes, as a powerful cell biology model, and to better understand the consequence of human actions on commensal bacteria at the population level. Herein we review the major findings, i.e., puzzle pieces, made with S. pneumoniae and how, over the years, they have come together to shape our understanding of this bacterium's biology and the practice of medicine and modern molecular biology.

Biofilm Formation by Nontypeable Haemophilus Influenzae and Resistance to Complement-Mediated Clearance

Biofilm formation has been suggested to be associated with phenotype changes compared with the planktonic form. We screened 1092 Haemophilus influenzae isolates for their genetic relationships and then selected 29 isolates from different genotypes and phenotypes and tested their ability to form biofilm. Our data showed a higher capacity of nontypable isolates, particularly isolates from respiratory and genital infections to form biofilm, compared with typable isolates. This ability to form biofilm was also correlated with reduced deposition of the complement component C3b on biofilm-involved bacteria. These data suggest that the biofilm formation contributes to the virulence of nontypable H. influenzae.

More than 40 years of cochlear implant research: A bibliometric analysis

OBJECTIVES

Cochlear implantation is the most effective treatment for patients with severe-to-profound sensorineural hearing loss. Much scientific work has been published since their inception. There is a need for a critical reflection on how and what we publish on cochlear implantation.

METHODS

All Science Citation Index Expanded featured articles between 1980 and 2022 with the word 'cochlear implants' or 'cochlear implantation' were collected from the Web of Science database. Separate characteristics, such as the publication dates, the journals, the number of citations, the countries of origin, the authors, the institutions and co-occurring keywords, were assessed.

RESULTS

13,934 articles were included in the data analysis. The journals of of Otology and Neurotology, Ear and Hearing and of Pediatric Otorhinolaryngology represent the top three most publishing journals. Hannover Medical School, the University of Melbourne and the University of Northern Iowa represent the top three most publishing institutions.

DISCUSSION

The amount of scientific publications on cochlear implant technology has increased for the last 40 years. Besides the focus on speech perception, the research landscape on cochlear implantation is broad and diverse. The number of countries and institutions contributing to these publications is limited.

CONCLUSION

This bibliometric analysis serves as a quantitative overview of the research landscape on cochlear implantation.

Modeling airway persistent infection of Moraxella catarrhalis and nontypeable Haemophilus influenzae by using human in vitro models

Non-typeable Haemophilus influenzae (NTHi) and Moraxella catarrhalis (Mcat) are two common respiratory tract pathogens often associated with acute exacerbations in Chronic Obstructive Pulmonary Disease (COPD) as well as with otitis media (OM) in children. Although there is evidence that these pathogens can adopt persistence mechanisms such as biofilm formation, the precise means through which they contribute to disease severity and chronicity remains incompletely understood, posing challenges for their effective eradication. The identification of potential vaccine candidates frequently entails the characterization of the host-pathogen interplay in vitro even though this approach is limited by the fact that conventional models do not permit long term bacterial infections. In the present work, by using air-liquid-interface (ALI) human airway in vitro models, we aimed to recreate COPD-related persistent bacterial infections. In particular, we explored an alternative use of the ALI system consisting in the assembly of an inverted epithelium grown on the basal part of a transwell membrane with the aim to enable the functionality of natural defense mechanisms such as mucociliary clearance and cellular extrusion that are usually hampered during conventional ALI infection experiments. The inversion of the epithelium did not affect tissue differentiation and considerably delayed NTHi or Mcat infection progression, allowing one to monitor host-pathogen interactions for up to three weeks. Notably, the use of these models, coupled with confocal and transmission electron microscopy, revealed unique features associated with NTHi and Mcat infection, highlighting persistence strategies including the formation of intracellular bacterial communities (IBCs) and surface-associated biofilm-like structures. Overall, this study demonstrates the possibility to perform long term host-pathogen investigations in vitro with the aim to define persistence mechanisms adopted by respiratory pathogens and individuate potential new vaccine targets.

Innovations in the Isolation and Treatment of Biofilms in Periprosthetic Joint Infection: A Comprehensive Review of Current and Emerging Therapies in Bone and Joint Infection Management

Periprosthetic joint infections (PJIs) are a devastating complication of joint arthroplasty surgeries that are often complicated by biofilm formation. The development of biofilms makes PJI treatment challenging as they create a barrier against antibiotics and host immune responses. This review article provides an overview of the current understanding of biofilm formation, factors that contribute to their production, and the most common organisms involved in this process. This article focuses on the identification of biofilms, as well as current methodologies and emerging therapies in the management of biofilms in PJI.

The burden of antibiotic resistance of the main microorganisms causing infections in humans - review of the literature

One of the biggest threats to human well-being and public health is antibiotic resistance. If allowed to spread unchecked, it might become a major health risk and trigger another pandemic. This proves the need to develop antibiotic resistance-related global health solutions that take into consideration microdata from various global locations. Establishing positive social norms, guiding individual and group behavioral habits that support global human health, and ultimately raising public awareness of the need for such action could all have a positive impact. Antibiotic resistance is not just a growing clinical concern but also complicates therapy, making adherence to current guidelines for managing antibiotic resistance extremely difficult. Numerous genetic components have been connected to the development of resistance; some of these components have intricate paths of transfer between microorganisms. Beyond this, the subject of antibiotic resistance is becoming increasingly significant in medical microbiology as new mechanisms underpinning its development are identified. In addition to genetic factors, behaviors such as misdiagnosis, exposure to broad-spectrum antibiotics, and delayed diagnosis contribute to the development of resistance. However, advancements in bioinformatics and DNA sequencing technology have completely transformed the diagnostic sector, enabling real-time identification of the components and causes of antibiotic resistance. This information is crucial for developing effective control and prevention strategies to counter the threat.

Biofilm-mediated infections by multidrug-resistant microbes: a comprehensive exploration and forward perspectives

A biofilm is a collection of microorganisms organized in a matrix of extracellular polymeric material. Biofilms consist of microbial cells that attach to both surfaces and each other, whether they are living or non-living. These microbial biofilms can lead to hospital-acquired infections and are generally detrimental. They possess the ability to resist the human immune system and antibiotics. The National Institute of Health (NIH) states that biofilm formation is associated with 65% of all microbial illnesses and 80% of chronic illnesses. Additionally, non-device-related microbial biofilm infections include conditions like cystic fibrosis, otitis media, infective endocarditis, and chronic inflammatory disorders. This review aims to provide an overview of research on chronic infections caused by microbial biofilms, methods used for biofilm detection, recent approaches to combat biofilms, and future perspectives, including the development of innovative antimicrobial strategies such as antimicrobial peptides, bacteriophages, and agents that disrupt biofilms.

Oral and middle ear delivery of otitis media standard of care antibiotics, but not biofilm-targeted antibodies, alter chinchilla nasopharyngeal and fecal microbiomes

Otitis media (OM) is one of the most globally pervasive pediatric conditions. Translocation of nasopharynx-resident opportunistic pathogens like nontypeable Haemophilus influenzae (NTHi) assimilates into polymicrobial middle ear biofilms, which promote OM pathogenesis and substantially diminish antibiotic efficacy. Oral or tympanostomy tube (TT)-delivered antibiotics remain the standard of care (SOC) despite consequences including secondary infection, dysbiosis, and antimicrobial resistance. Monoclonal antibodies (mAb) against two biofilm-associated structural proteins, NTHi-specific type IV pilus PilA (anti-rsPilA) and protective tip-region epitopes of NTHi integration host factor (anti-tip-chimer), were previously shown to disrupt biofilms and restore antibiotic sensitivity in vitro. However, the additional criterion for clinical relevance includes the absence of consequential microbiome alterations. Here, nine chinchilla cohorts (n = 3/cohort) without disease were established to evaluate whether TT delivery of mAbs disrupted nasopharyngeal or fecal microbiomes relative to SOC-OM antibiotics. Cohort treatments included a 7d regimen of oral amoxicillin-clavulanate (AC) or 2d regimen of TT-delivered mAb, AC, Trimethoprim-sulfamethoxazole (TS), ofloxacin, or saline. Fecal and nasopharyngeal lavage (NPL) samples were collected before and several days post treatment (DPT) for 16S sequencing. While antibiotic-treated cohorts displayed beta-diversity shifts (PERMANOVA, P < 0.05) and reductions in alpha diversity (q < 0.20) relative to baseline, mAb antibodies failed to affect diversity, indicating maintenance of a eubiotic state. Taxonomic and longitudinal analyses showed blooms in opportunistic pathogens (ANCOM) and greater magnitudes of compositional change (P < 0.05) following broad-spectrum antibiotic but not mAb treatments. Collectively, results showed broad-spectrum antibiotics induced significant fecal and nasopharyngeal microbiome disruption regardless of delivery route. Excitingly, biofilm-targeting antibodies had little effect on fecal and nasopharyngeal microbiomes.

Pharmacodynamic, pharmacokinetic, toxicity, and recent advances in Eugenol's potential benefits against natural and chemical noxious agents: A mechanistic review

The active biological phytochemicals, crucial compounds employed in creating hundreds of medications, are derived from valuable and medicinally significant plants. These phytochemicals offer excellent protection from various illnesses, including inflammatory disorders and chronic conditions caused by oxidative stress. A phenolic monoterpenoid known as eugenol (EUG), it is typically found in the essential oils of many plant species from the Myristicaceae, Myrtaceae, Lamiaceae, and Lauraceae families. One of the main ingredients of clove oil (Syzygium aromaticum (L.), Myrtaceae), it has several applications in industry, including flavoring food, pharmaceutics, dentistry, agriculture, and cosmeceuticals. Due to its excellent potential for avoiding many chronic illnesses, it has lately attracted attention. EUG has been classified as a nonmutant, generally acknowledged as a safe (GRAS) chemical by the World Health Organization (WHO). According to the existing research, EUG possesses notable anti-inflammatory, antioxidant, analgesic, antibacterial, antispasmodic, and apoptosis-promoting properties, which have lately gained attention for its ability to control chronic inflammation, oxidative stress, and mitochondrial malfunction and dramatically impact human wellness. The purpose of this review is to evaluate the scientific evidence from the most significant research studies that have been published regarding the protective role and detoxifying effects of EUG against a wide range of toxins, including biological and chemical toxins, as well as different drugs and pesticides that produce a variety of toxicities, throughout view of the possible advantages of EUG.

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.

Safety, tolerability, and effect of a single aural dose of Dornase alfa at the time of ventilation tube surgery for otitis media: A Phase 1b double randomized control trial

BACKGROUND

One third of children require repeat ventilation tube insertion (VTI) for otitis media. Disease recurrence is associated with persistent middle ear bacterial biofilms. With demonstration that Dornase alfa (a DNase) disrupts middle ear effusion biofilms ex vivo, we identified potential for this as an anti-biofilm therapy to prevent repeat VTI. First, safety and tolerability needed to be measured.

METHODS

This was a phase 1B double-blinded randomized control trial conducted in Western Australia. Children between 6 months and 5 years undergoing VTI for bilateral middle ear effusion were recruited between 2012 and 2014 and followed for two years. Children's ears were randomized to receive either Dornase alfa (1 mg/mL) or 0.9 % sodium chloride (placebo) at time of surgery. Children were followed up at 2 weeks post-VTI and at 3-monthly intervals for 2 years. Outcomes assessed were: 1) safety and tolerability, 2) otorrhoea frequency, 3) blocked or extruded ventilation tube (VT) frequency, 4) time to blockage or extrusion, 5) time to infection recurrence and/or need for repeat VTI.

RESULTS

Sixty children (mean age 2.3 years) were enrolled with 87 % reaching study endpoint. Treatment did not change otorrhoea frequency. Hearing improved in all children following VTI, with no indication of ototoxicity. Dornase alfa had some effect on increasing time until VT extrusion (p = 0.099); and blockage and/or extrusion (p = 0.122). Frequency of recurrence and time until recurrence were similar. Fourteen children required repeat VTI within the follow-up period.

CONCLUSION

A single application of Dornase alfa into the middle ear at time of VTI was safe, non-ototoxic, and well-tolerated.

TRIAL REGISTRATION

ACTRN12623000504617.

Changes in Pre- and Post-adenoidectomy Bacterial Profile in Children With Chronic Rhinosinusitis

OBJECTIVE

We aimed to investigate the difference between the bacterial profiles of the nasal cavities and adenoid surfaces of children with chronic rhinosinusitis (CRS). We also intended to determine and analyze the potential correlation between the pre- and post-adenoidectomy differences in the nasal bacterial profile and clinical prognosis.

METHODS

The clinical information of pediatric patients was collected. All the children underwent adenoidectomy (with or without tonsillectomy), and swab samples were collected during the operation. Visual analog scales (VAS) were used at 3, 6, and 12 months postoperatively. At the 12-month follow-up examination, swab samples were collected again. PCR amplification was performed of the v3-v4 variable regions of 16S rRNA of the collected specimens, as well as high-throughput sequencing using the Illumina platform. The species information was obtained by OTUs clustering, species annotation, and α-diversity analysis.

RESULTS

Twenty-two male and eight female pediatric patients were included in the investigation The most abundant genus level bacterial representatives on the nasal surface before adenoidectomy were Moraxella catarrh, Streptococcus pneumoniae, Haemophilus influenzae, and Staphylococcus aureus, whereas on the surface of adenoids, they were Streptococcus pneumonia, Haemophilus influenza, Nucleobacter, and Moraxella catarrhalis. One year postoperatively, the bacteria with the highest abundance on the nasal surface at the genus level were Moraxella catarrhalis, Streptococcus pneumonia, Staphylococcus aureus, and non-culturable Dolosigranulum. One year postoperatively, the bacterial richness in the nasal cavity was significantly higher than at baseline (P < .05). Furthermore, the subjective nasal score of all children significantly decreased at 3, 6, and 12 months postoperatively (P < .01).

CONCLUSION

The preoperative bacterial abundance of the nasal cavity and the adenoid surfaces was similar, showing a clear correlation. No single specific bacterium was established to be a dominant species associated with the development of CRS in children. The post-adenoidectomy bacterial richness in the nasal cavity was significantly increased, which may be closely related to the relief of postoperative sinusitis symptoms.

Establishment of a consensus protocol to explore the brain pathobiome in patients with mild cognitive impairment and Alzheimer's disease: Research outline and call for collaboration

Microbial infections of the brain can lead to dementia, and for many decades microbial infections have been implicated in Alzheimer's disease (AD) pathology. However, a causal role for infection in AD remains contentious, and the lack of standardized detection methodologies has led to inconsistent detection/identification of microbes in AD brains. There is a need for a consensus methodology; the Alzheimer's Pathobiome Initiative aims to perform comparative molecular analyses of microbes in post mortem brains versus cerebrospinal fluid, blood, olfactory neuroepithelium, oral/nasopharyngeal tissue, bronchoalveolar, urinary, and gut/stool samples. Diverse extraction methodologies, polymerase chain reaction and sequencing techniques, and bioinformatic tools will be evaluated, in addition to direct microbial culture and metabolomic techniques. The goal is to provide a roadmap for detecting infectious agents in patients with mild cognitive impairment or AD. Positive findings would then prompt tailoring of antimicrobial treatments that might attenuate or remit mounting clinical deficits in a subset of patients.

Immunomodulation of periodontitis with SPMs

Inflammation is a critical component in the pathophysiology of numerous disease processes, with most therapeutic modalities focusing on its inhibition in order to achieve treatment outcomes. The resolution of inflammation is a separate, distinct pathway that entails the reversal of the inflammatory process to a state of homoeostasis rather than selective inhibition of specific components of the inflammatory cascade. The discovery of specialized pro-resolving mediators (SPMs) resulted in a paradigm shift in our understanding of disease etiopathology. Periodontal disease, traditionally considered as one of microbial etiology, is now understood to be an inflammation-driven process associated with dysbiosis of the oral microbiome that may be modulated with SPMs to achieve therapeutic benefit.

Outcomes of Mastoidectomy With Antibiotic Catheter Irrigation for Patients With Draining Ventilation Tubes

OBJECTIVES

To evaluate the effectiveness of mastoidectomy with antibiotic catheter irrigation in patients with chronic tympanostomy tube otorrhea.

METHODS

A chart review of adult and pediatric patients with persistent tympanostomy tube otorrhea who had failed outpatient medical management and underwent mastoidectomy with placement of a temporary indwelling catheter for antibiotic instillation was performed. Patients were retrospectively followed for recurrent drainage after 2 months and outcomes were categorized as resolution (0-1 episodes of otorrhea or otitis media with effusion during follow-up), improvement (2-3 episodes), or continued episodic (>3 episodes).

RESULTS

There were 22 patients and 23 operated ears. Median age was 46 years (interquartile range, IQR = 29-65). The median duration of otorrhea from referral was 5.5 months (IQR = 2.8-12). Following surgery, 14 ears had resolution of drainage, 6 had improvement, and 3 had episodic. The observed percentage of resolved/improved ears (87%) was significant (P = .0005, 95% CI = 67.9%-95.5%). Median follow-up time was 25 months (IQR = 12-59). Pre and postoperative pure tone averages improved (difference of medians = -3.3 dB, P = .02) with no significant difference in word recognition scores (P = .68). Methicillin-resistant Staphylococcus aureus was the most common isolated microbe while no growth was most frequently noted on intraoperative cultures.

CONCLUSIONS

Mastoidectomy with antibiotic catheter irrigation may be an effective surgical strategy, and single stage alternative to intravenous antibiotics, for select patients with persistent tube otorrhea who have failed topical and oral antibiotics.

Characterization of gut microbiota profile in Iranian patients with bipolar disorder compared to healthy controls

Introduction

The human gut microbiota plays a crucial role in mental health through the gut-brain axis, impacting central nervous system functions, behavior, mood, and anxiety. Consequently, it is implicated in the development of neuropsychiatric disorders. This study aimed to assess and compare the gut microbiota profiles and populations of individuals with bipolar disorder and healthy individuals in Iran.

Methods

Fecal samples were collected from 60 participants, including 30 bipolar patients (BPs) and 30 healthy controls (HCs), following rigorous entry criteria. Real-time quantitative PCR was utilized to evaluate the abundance of 10 bacterial genera/species and five bacterial phyla.

Results

Notably, Actinobacteria and Lactobacillus exhibited the greatest fold change in BPs compared to HCs at the phylum and genus level, respectively, among the bacteria with significant population differences. Ruminococcus emerged as the most abundant genus in both groups, while Proteobacteria and Bacteroidetes showed the highest abundance in BPs and HCs, respectively, at the phylum level. Importantly, our investigation revealed a lower Firmicutes/Bacteroidetes ratio, potentially serving as a health indicator, in HCs compared to BPs.

Conclusion

This study marks the first examination of an Iranian population and provides compelling evidence of significant differences in gut microbiota composition between BPs and HCs, suggesting a potential link between brain functions and the gut microbial profile and population.

Bacterial biofilms in the human body: prevalence and impacts on health and disease

Bacterial biofilms can be found in most environments on our planet, and the human body is no exception. Consisting of microbial cells encased in a matrix of extracellular polymers, biofilms enable bacteria to sequester themselves in favorable niches, while also increasing their ability to resist numerous stresses and survive under hostile circumstances. In recent decades, biofilms have increasingly been recognized as a major contributor to the pathogenesis of chronic infections. However, biofilms also occur in or on certain tissues in healthy individuals, and their constituent species are not restricted to canonical pathogens. In this review, we discuss the evidence for where, when, and what types of biofilms occur in the human body, as well as the diverse ways in which they can impact host health under homeostatic and dysbiotic states.

The role of AJB35136 and fdtA genes in biofilm formation by avian pathogenic Escherichia coli

BACKGROUND

Infections caused by avian pathogenic Escherichia coli (APEC) result in significant economic losses in poultry industry. APEC strains are known to form biofilms in various conditions allowing them to thrive even under harsh and nutrient-deficient conditions on different surfaces, and this ability enables them to evade chemical and biological eradication methods. Despite knowing the whole genome sequences of various APEC isolates, little has been reported regarding their biofilm-associated genes. A random transposon mutant library of the wild-type APEC IMT 5155 comprising 1,300 mutants was analyzed for biofilm formation under nutrient deprived conditions using Videoscan technology coupled with fluorescence microscopy. Seven transposon mutants were found to have reproducibly and significantly altered biofilm formation and their mutated genes were identified by arbitrary PCR and DNA sequencing. The intact genes were acquired from the wild-type strain, cloned in pACYC177 plasmid and transformed into the respective altered biofilm forming transposon mutants, and the biofilm formation was checked in comparison to the wild type and mutant strains under the same conditions.

RESULTS

In this study, we report seven genes i.e., nhaA, fdeC, yjhB, lysU, ecpR, AJB35136 and fdtA of APEC with significant contribution to biofilm formation. Reintroduction of AJB35136 and fdtA, reversed the altered phenotype proving that a significant role being played by these two O-antigen related genes in APEC biofilm formation. Presence of these seven genes across nonpathogenic E. coli and APEC genomes was also analyzed showing that they are more prevalent in the latter.

CONCLUSIONS

The study has elucidated the role of these genes in APEC biofilm formation and compared them to adhesion expanding the knowledge and understanding of the economically significant pathogens.

A novel immuno-molecular strategy for the detection of Streptococcus pneumoniae serotypes in human cerebrospinal and middle ear fluids

Streptococcus pneumoniae is one of the most common microorganisms causing acute otitis media (AOM) in children. While bacterial culture of middle ear fluid (MEF) is the gold standard to detect the etiological organisms, several host and pathogen factors impact the survival of the organisms resulting in false negatives. To overcome this limitation, we have developed and validated an innovative multiplex immuno-molecular assay to screen and detect the S. pneumoniae 15-valent pneumococcal conjugate vaccine (PCV15; STs 1, 3, 4, 5, 6A, 6B, 7F, 9V, 14, 18C, 19A, 19F, 22F, 23F, and 33F) vaccine serotypes in MEF. This novel in vitro approach involves two-step testing. First, the MEF specimens were tested for highly conserved pneumococcal genes, autolysin, lytA, and pneumolysin, ply using direct PCR to identify pneumococcus positive specimens. The pneumococcus positive specimens were screened for the presence of vaccine serotype specific pneumococcal polysaccharides using a 15-plex Pneumococcal Antigen Detection (PAD) assay, with specific capture and detection monoclonal antibodies. Due to the lack of availability of MEF samples, cerebrospinal fluid (CSF) was used as the surrogate matrix for the development and validation of the PCR-PAD assays. The PCR and PAD assays were separately evaluated for sensitivity and specificity. Subsequently, the PCR-PAD assays were cross-validated with human MEF samples (n = 39) which were culture confirmed to contain relevant bacterial strains. The combined PCR-PAD assays demonstrated high rate of agreement 94.9% (95% CI; 82.7, 99.4%) with historical Quellung serotype data of these MEF samples. This novel PCR-PAD assay demonstrates the feasibility of combining molecular and immunological assays to screen and identify PCV15 pneumococcal vaccine serotypes in AOM clinical samples.

In Vivo Optical Characterization of Middle Ear Effusions and Biofilms During Otitis Media

Otitis media (OM), a common ear infection, is characterized by the presence of an accumulated middle ear effusion (MEE) in a normally air-filled middle ear cavity. While assessing the MEE plays a critical role in the overall management of OM, identifying and examining the MEE is challenging with the current diagnostic tools since the MEE is located behind the semi-opaque eardrum. The objective of this cross-sectional, observational study is to non-invasively visualize and characterize MEEs and bacterial biofilms in the middle ear. A portable, handheld, otoscope-integrated optical coherence tomography (OCT) system combined with novel analytical methods has been developed. In vivo middle ear OCT images were acquired from 53 pediatric subjects (average age of 3.9 years; all awake during OCT imaging) diagnosed with OM and undergoing a surgical procedure (ear tube surgery) to aspirate the MEE and aerate the middle ear. In vivo middle ear OCT acquired prior to the surgery was compared with OCT of the freshly extracted MEEs, clinical diagnosis, and post-operative evaluations. Among the subjects who were identified with the presence of MEEs, 89.6% showed the presence of the TM-adherent biofilm in in vivo OCT. This study provides an atlas of middle ear OCT images exhibiting a range of depth-resolved MEE features, which can only be visualized and assessed non-invasively through OCT. Quantitative metrics of OCT images acquired prior to the surgery were statistically correlated with surgical evaluations of MEEs. Measurements of MEE characteristics will provide new readily available information that can lead to improved diagnosis and management strategies for the highly prevalent OM in children.

Identification of natural diterpenes isolated from Azorella species targeting dispersin B using in silico approaches

CONTEXT

A bacterial biofilm is a cluster of bacterial cells embedded in a self-produced matrix of extracellular polymeric substances such as DNA, proteins, and polysaccharides. Several diseases have been reported to cause by bacterial biofilms, and difficulties in treating these infections are of concern. This work aimed to identify the inhibitor with the highest binding affinity for the receptor protein by screening various inhibitors obtained from Azorella species for a potential target to inhibit dispersin B. This work shows that azorellolide has the highest binding affinity (- 8.2 kcal/mol) among the compounds tested, followed by dyhydroazorellolide, mulinone A, and 7-acetoxy-mulin-9,12-diene which all had a binding affinity of - 8.0 kcal/mol. To the best of our knowledge, this is the first study to evaluate and contrast several diterpene compounds as antibacterial biofilm chemicals.

METHODS

Here, molecular modelling techniques tested 49 diterpene compounds of Azorella and six FDA-approved antibiotics medicines for antibiofilm activity. Since protein-like interactions are crucial in drug discovery, AutoDock Vina was initially employed to carry out structure-based virtual screening. The drug-likeness and ADMET properties of the chosen compounds were examined to assess the antibiofilm activity further. Lipinski's rule of five was then applied to determine the antibiofilm activity. Then, molecular electrostatic potential was used to determine the relative polarity of a molecule using the Gaussian 09 package and GaussView 5.08. Following three replica molecular dynamic simulations (using the Schrodinger program, Desmond 2019-4 package) that each lasted 100 ns on the promising candidates, binding free energy was estimated using MM-GBSA. Structural visualisation was used to test the binding affinity of each compound to the crystal structure of dispersin B protein (PDB: 1YHT), a well-known antibiofilm compound.

Toxin-antitoxin systems in bacterial pathogenesis

Toxin-Antitoxin (TA) systems are abundant in prokaryotes and play an important role in various biological processes such as plasmid maintenance, phage inhibition, stress response, biofilm formation, and dormant persister cell generation. TA loci are abundant in pathogenic intracellular micro-organisms and help in their adaptation to the harsh host environment such as nutrient deprivation, oxidation, immune response, and antimicrobials. Several studies have reported the involvement of TA loci in establishing successful infection, intracellular survival, better colonization, adaptation to host stresses, and chronic infection. Overall, the TA loci play a crucial role in bacterial virulence and pathogenesis. Nonetheless, there are some controversies about the role of TA system in stress response, biofilm and persister formation. In this review, we describe the role of the TA systems in bacterial virulence. We discuss the important features of each type of TA system and the recent discoveries identifying key contributions of TA loci in bacterial pathogenesis.

Analysis of Bacterial Biofilm Formation and MUC5AC and MUC5B Expression in Chronic Rhinosinusitis Patients

Chronic rhinosinusitis (CRS) is a condition affecting as much as 16% of the adult population in developed countries with many factors attributed to its development, including the more recently proposed role of bacterial biofilm infections. Plenty of research has been conducted on biofilms in CRS and the causes behind the development of such an infection in the nasal cavity and sinuses. One such probable cause is the production of mucin glycoproteins by the mucosa of the nasal cavity. To investigate the possible link between biofilm formation and mucin expression levels and their relationship with CRS etiology, we examined samples from 85 patients by means of spinning disk confocal microscopy (SDCM) to establish their biofilm status and quantitative reverse transcription polymerase chain reaction (qRT-PCR) to determine MUC5AC and MUC5B expression levels. We observed a significantly higher prevalence of bacterial biofilms in the CRS patient group compared to the control group. In addition, we detected higher expression levels of MUC5B but not MUC5AC in the CRS group, which suggested a possible role for MUC5B in CRS development. Finally, we found no direct relationship between biofilm presence and mucin expression levels, thereby showing a multifaceted connection between these two major factors implicated in CRS etiology.

Biofilm-Forming Bacteria Implicated in Complex Otitis Media in Children in the Post-Heptavalent Pneumococcal Conjugate Vaccine (PCV7) Era

Background: Chronic media with effusion (COME) and recurrent acute otitis media (RAOM) are closely related clinical entities that affect childhood. The aims of the study were to investigate the microbiological profile of otitis-prone children in the post-PCV7 era and, to examine the biofilm-forming ability in association with clinical history and outcome during a two-year post-operative follow-up. Methods: In this prospective study, pathogens from patients with COME and RAOM were isolated and studied in vitro for their biofilm-forming ability. The minimum inhibitory concentrations (MIC) of both the planktonic and the sessile forms were compared. The outcome of the therapeutic method used in each case and patient history were correlated with the pathogens and their ability to form biofilms. Results: Haemophilus influenzae was the leading pathogen (35% in COME and 40% in RAOM), and Streptococcus pneumoniae ranked second (12% in COME and 24% in RAOM). Polymicrobial infections were identified in 5% of COME and 19% of RAOM cases. Of the isolated otopathogens, 94% were positive for biofilm formation. Conclusions: This is the first Greek research studying biofilm formation in complex otitis media-prone children population in the post-PCV7 era. High rates of polymicrobial infections, along with treatment failure in biofilms, may explain the lack of antimicrobial efficacy in otitis-prone children.

Role of Streptococcus pneumoniae extracellular glycosidases in immune evasion

Streptococcus pneumoniae (pneumococcus) typically colonizes the human upper airway asymptomatically but upon reaching other sites of the host body can cause an array of diseases such as pneumonia, bacteremia, otitis media, and meningitis. Be it colonization or progression to disease state, pneumococcus faces multiple challenges posed by host immunity ranging from complement mediated killing to inflammation driven recruitment of bactericidal cells for the containment of the pathogen. Pneumococcus has evolved several mechanisms to evade the host inflicted immune attack. The major pneumococcal virulence factor, the polysaccharide capsule helps protect the bacteria from complement mediated opsonophagocytic killing. Another important group of pneumococcal proteins which help bacteria to establish and thrive in the host environment is surface associated glycosidases. These enzymes can hydrolyze host glycans on glycoproteins, glycolipids, and glycosaminoglycans and consequently help bacteria acquire carbohydrates for growth. Many of these glycosidases directly or indirectly facilitate bacterial adherence and are known to modulate the function of host defense/immune proteins likely by removing glycans and thereby affecting their stability and/or function. Furthermore, these enzymes are known to contribute the formation of biofilms, the bacterial communities inherently resilient to antimicrobials and host immune attack. In this review, we summarize the role of these enzymes in host immune evasion.

Impact of IL-17-producing γδ T cells on chronic otitis media induced by nontypeable Haemophilus influenzae in a mouse model

Nontypeable Haemophilus influenzae (NTHi) is considered a major pathogen underlying middle ear infection. This study aimed to investigate the impact of IL-17 on chronic otitis media (COM) induced by NTHi in mice. NTHi was inoculated into the tympanic bulla with eustachian tubal obstruction. Middle ear effusions (MEEs) and tissues were collected on days 3, 14, and at 1, 2, and 6 months after injection. The expression of interleukin-17A (IL-17A) in MEEs was significantly elevated compared to that in the control group at the translational and transcriptional levels during the experiments. The quantities of IL-17-producing γδ T cells were significantly increased compared to that in the control group during COM, but that of Th17 cells did not. Depletion of γδ T cells by anti-γδ T-cell receptor (TCR) monoclonal antibody (mAb) administration significantly decreased the bacteria counts and the concentrations of IL-1β, IL-6, IL-17A, TNF-α, and IL-10 in MEEs. Our results suggest that IL-17 may play an important role in prolonging the inflammation in the middle ear in COM and that IL-17-producing γδ T cells may contribute to the exacerbated inflammatory response in the middle ear. In this study, anti-γδ TCR mAb administration was found to improve chronic middle ear inflammatory conditions.

Antibiotic Tolerance Indicative of Persistence Is Pervasive among Clinical Streptococcus pneumoniae Isolates and Shows Strong Condition Dependence

Streptococcus pneumoniae is an important human pathogen, being one of the most common causes of community-acquired pneumonia and otitis media. Antibiotic resistance in S. pneumoniae is an emerging problem, as it depletes our arsenal of effective drugs. In addition, persistence also contributes to the antibiotic crisis in many other pathogens, yet for S. pneumoniae, little is known about antibiotic-tolerant persisters and robust experimental means are lacking. Persister cells are phenotypic variants that exist as a subpopulation within a clonal culture. Being tolerant to lethal antibiotics, they underly the chronic nature of a variety of infections and even help in acquiring genetic resistance. In this study, we set out to identify and characterize persistence in S. pneumoniae. Specifically, we followed different strategies to overcome the self-limiting nature of S. pneumoniae as a confounding factor in the prolonged monitoring of antibiotic survival needed to study persistence. Under optimized conditions, we identified genuine persisters in various growth phases and for four relevant antibiotics through biphasic survival dynamics and heritability assays. Finally, we detected a high variety in antibiotic survival levels across a diverse collection of S. pneumoniae clinical isolates, which assumes that a high natural diversity in persistence is widely present in S. pneumoniae. Collectively, this proof of concept significantly progresses the understanding of the importance of antibiotic persistence in S. pneumoniae infections, which will set the stage for characterizing its relevance to clinical outcomes and advocates for increased attention to the phenotype in both fundamental and clinical research. IMPORTANCE S. pneumoniae is considered a serious threat by the Centers for Disease Control and Prevention because of rising antibiotic resistance. In addition to resistance, bacteria can also survive lethal antibiotic treatment by developing antibiotic tolerance, more specifically, antibiotic tolerance through persistence. This phenotypic variation seems omnipresent among bacterial life, is linked to therapy failure, and acts as a catalyst for resistance development. This study gives the first proof of the presence of persister cells in S. pneumoniae and shows a high variety in persistence levels among diverse strains, suggesting that persistence is a general trait in S. pneumoniae cultures. Our work advocates for higher interest for persistence in S. pneumoniae as a contributing factor for therapy failure and resistance development.

Chronic clinical signs of upper respiratory tract disease associate with gut and respiratory microbiomes in a cohort of domestic felines

Feline upper respiratory tract disease (FURTD), often caused by infections etiologies, is a multifactorial syndrome affecting feline populations worldwide. Because of its highly transmissible nature, infectious FURTD is most prevalent anywhere cats are housed in groups such as animal shelters, and is associated with negative consequences such as decreasing adoption rates, intensifying care costs, and increasing euthanasia rates. Understanding the etiology and pathophysiology of FURTD is thus essential to best mitigate the negative consequences of this disease. Clinical signs of FURTD include acute respiratory disease, with a small fraction of cats developing chronic sequelae. It is thought that nasal mucosal microbiome changes play an active role in the development of acute clinical signs, but it remains unknown if the microbiome may play a role in the development and progression of chronic clinical disease. To address the knowledge gap surrounding how microbiomes link to chronic FURTD, we asked if microbial community structure of upper respiratory and gut microbiomes differed between cats with chronic FURTD signs and clinically normal cats. We selected 8 households with at least one cat exhibiting chronic clinical FURTD, and simultaneously collected samples from cohabitating clinically normal cats. Microbial community structure was assessed via 16S rDNA sequencing of both gut and nasal microbiome communities. Using a previously described ecophylogenetic method, we identified 136 and 89 microbial features within gut and nasal microbiomes respectively that significantly associated with presence of active FURTD clinical signs in cats with a history of chronic signs. Overall, we find that nasal and gut microbial community members associate with the presence of chronic clinical course, but more research is needed to confirm our observations.

Middle Ear Condition at the Time of Pediatric Myringotomy Tube Placement: Pain Associations Following Intraoperative Fentanyl/Ketorolac and Seasonal Variation

BACKGROUND

Ketorolac-refractory pain behavior following bilateral myringotomy and pressure equalization tube placement (BMT) is associated with the absence of middle ear fluid. Intraoperative fentanyl/ketorolac affords more reliable pain control than ketorolac alone. We hypothesized that middle ear condition would correlate with postoperative pain despite such combination therapy. We further sought to demonstrate seasonal variation in ear condition and its influence on pain.

METHODS

We conducted a single-institution retrospective cohort study of healthy children (9 months-7 years), who underwent BMT by a single surgeon from 2015 to 2020. Anesthetic care included sevoflurane/nitrous oxide/oxygen/air by mask and intramuscular fentanyl/ketorolac. Left/right middle ear fluid status was recorded at the time of BMT, and ear condition (primary exposure) was dichotomized as bilateral infected (mucoid or purulent) or normal/unilateral infected. The primary outcome was maximum postanesthesia care unit Face, Legs, Activity, Cry, and Consolability (FLACC) score: 4-10 (moderate-to-severe pain) versus 0-3 (no-to-low pain). Rescue oxycodone, acetaminophen administration, and emergence agitation were secondary outcomes. Statistical analysis incorporated generalized linear mixed-effect models (GLMMs) with random intercepts to account for clustering by anesthesia provider. A year-over-year monthly time-series analysis was conducted using an autoregressive integrated moving average (ARIMA) regression model.

RESULTS

Excluding recurrent cases, 1149 unique evaluable subjects remained. Bilateral infection prevalence was 39.8% (457/1149; 95% confidence interval [CI], 37.0-42.6). Probability of moderate-to-severe pain behavior was 23.5% (270/1149; 95% CI, 21.1-26.0) overall. Compared to patients with bilateral infected middle ears, those with normal/unilateral infected ears were more likely to have a FLACC score ≥4 (26.7% [185/692] versus 18.6% [85/457]; odds ratio [95% CI], 1.7 [1.2-2.3]; P = .002). Variability in pain outcome explained by the multivariable GLMM was 4.7%. Fentanyl dose response was evidenced by oxycodone administration differences ( P ≤ 0.002). Moderate-to-severe pain and emergence agitation were more likely with reduced fentanyl dosing. Bilateral infection prevalence exhibited seasonality, peaking in March and nadiring in July. However, pain outcomes did not vary by season.

CONCLUSIONS

Normal/unilateral infected ears at time of pediatric BMT are associated with higher incidence of moderate-to-severe postoperative pain following intraoperative fentanyl/ketorolac administration, but the predictive value of ear condition on pain is limited. Infections were less common in the summer.

Endoscope-assisted magnetic helical micromachine delivery for biofilm eradication in tympanostomy tube

Occlusion of the T-tube (tympanostomy tube) is a common postoperative sequela related to bacterial biofilms. Confronting biofilm-related infections of T-tubes, maneuverable and effective treatments are still challenging presently. Here, we propose an endoscopy-assisted treatment procedure based on the wobbling Fe₂O₃ helical micromachine (HMM) with peroxidase-mimicking activity. Different from the ideal corkscrew motion, the Fe₂O₃ HMM applies a wobbling motion in the tube, inducing stronger mechanical force and fluid convections, which not only damages the biofilm occlusion into debris quickly but also enhances the catalytic generation and diffusion of reactive oxygen species (ROS) for killing bacteria cells. Moreover, the treatment procedure, which integrated the delivery, actuation, and retrieval of Fe₂O₃ HMM, was validated in the T-tube implanted in a human cadaver ex vivo. It enables the visual operation with ease and is gentle to the tympanic membrane and ossicles, which is promising in the clinical application.

The biofilm life cycle: expanding the conceptual model of biofilm formation

Bacterial biofilms are often defined as communities of surface-attached bacteria and are typically depicted with a classic mushroom-shaped structure characteristic of Pseudomonas aeruginosa. However, it has become evident that this is not how all biofilms develop, especially in vivo, in clinical and industrial settings, and in the environment, where biofilms often are observed as non-surface-attached aggregates. In this Review, we describe the origin of the current five-step biofilm development model and why it fails to capture many aspects of bacterial biofilm physiology. We aim to present a simplistic developmental model for biofilm formation that is flexible enough to include all the diverse scenarios and microenvironments where biofilms are formed. With this new expanded, inclusive model, we hereby introduce a common platform for developing an understanding of biofilms and anti-biofilm strategies that can be tailored to the microenvironment under investigation.

Biofilm aggregates and the host airway-microbial interface

Biofilms are multicellular microbial aggregates that can be associated with host mucosal epithelia in the airway, gut, and genitourinary tract. The host environment plays a critical role in the establishment of these microbial communities in both health and disease. These host mucosal microenvironments however are distinct histologically, functionally, and regarding nutrient availability. This review discusses the specific mucosal epithelial microenvironments lining the airway, focusing on: i) biofilms in the human respiratory tract and the unique airway microenvironments that make it exquisitely suited to defend against infection, and ii) how airway pathophysiology and dysfunctional barrier/clearance mechanisms due to genetic mutations, damage, and inflammation contribute to biofilm infections. The host cellular responses to infection that contribute to resolution or exacerbation, and insights about evaluating and therapeutically targeting airway-associated biofilm infections are briefly discussed. Since so many studies have focused on Pseudomonas aeruginosa in the context of cystic fibrosis (CF) or on Haemophilus influenzae in the context of upper and lower respiratory diseases, these bacteria are used as examples. However, there are notable differences in diseased airway microenvironments and the unique pathophysiology specific to the bacterial pathogens themselves.

The central role of arginine in Haemophilus influenzae survival in a polymicrobial environment with Streptococcus pneumoniae and Moraxella catarrhalis

Haemophilus influenzae, Streptococcus pneumoniae and Moraxella catarrhalis are bacterial species which frequently co-colonise the nasopharynx, but can also transit to the middle ear to cause otitis media. Chronic otitis media is often associated with a polymicrobial infection by these bacteria. However, despite being present in polymicrobial infections, the molecular interactions between these bacterial species remain poorly understood. We have previously reported competitive interactions driven by pH and growth phase between H. influenzae and S. pneumoniae. In this study, we have revealed competitive interactions between the three otopathogens, which resulted in reduction of H. influenzae viability in co-culture with S. pneumoniae and in triple-species culture. Transcriptomic analysis by mRNA sequencing identified a central role of arginine in mediating these interactions. Arginine supplementation was able to increase H. influenzae survival in a dual-species environment with S. pneumoniae, and in a triple-species environment. Arginine was used by H. influenzae for ATP production, and levels of ATP generated in dual- and triple-species co-culture at early stages of growth were significantly higher than the combined ATP levels of single-species cultures. These results indicate a central role for arginine-mediated ATP production by H. influenzae in the polymicrobial community.

Interleukin-33 and thymic stromal lymphopoietin are primary cytokines involved in the Th1/Th2 inflammatory response in chronic secretory otitis media

Background:

T-helper (Th)1/Th2 inflammatory responses are responsible for secretory otitis media (SOM) development. However, the mechanisms underlying these immune responses remain unknown. This study aims to identify the primary cytokines that play essential roles in chronic SOM.

Methods:

Two groups were established for the present study: chronic SOM group ( n = 21) and control group ( n = 10). The middle ear effusion and serum samples of the expression cytokines (interleukin IL-2, IL-4, IL-5, IL-13, IL-17, IL-25, IL-33, interferon [IFN]-γ, thymic stromal lymphopoietin [TSLP], immunoglobulin IgE, and pepsins) were analyzed by enzyme-linked immunosorbent assay.

Results:

The levels of IL-4, IL-5, IL-13, IL-17, IL-25, IFN-γ, TLSP, pepsins, IL-2, and IL-33 (all, p < 0.001) were higher in middle ear effusion, when compared to those in serum, in chronic SOM group (non-paired sample). However, there was no significant difference in serum expression for those cytokines compared chronic SOM group and control group. The paired sample expression for IL-33 and TLSP (both, p = 0.046) were higher compared the effusion and serum in chronic SOM group.

Conclusions:

IL-33 produces inflammatory cytokines, such as IL-1b, IL-6, TNF-α, IL-10, IL-4, and TGF-β, which through nucleus into cytoplasm causing inflammatory responses. The present study revealed that IL-33 also produce IL-17, IL-4, IL-5, and IL-13 inflammatory factors, triggering an inflammatory response. Study reported that the combined stimulation of TSLP and IL-33 elicits an approximately 10-fold increase in cytokine production, when compared to the stimulation of IL-33 alone. This suggests that IL-33 and TLSP may be the primary cytokines involved in Th1/Th2 inflammatory responses in chronic SOM.

Automated classification of otitis media with OCT: augmenting pediatric image datasets with gold-standard animal model data

Otitis media (OM) is an extremely common disease that affects children worldwide. Optical coherence tomography (OCT) has emerged as a noninvasive diagnostic tool for OM, which can detect the presence and quantify the properties of middle ear fluid and biofilms. Here, the use of OCT data from the chinchilla, the gold-standard OM model for the human disease, is used to supplement a human image database to produce diagnostically relevant conclusions in a machine learning model. Statistical analysis shows the datatypes are compatible, with a blended-species model reaching ∼95% accuracy and F1 score, maintaining performance while additional human data is collected.

In Vitro Fiber-Probe-Based Identification of Pathogens in Biofilms by Raman Spectroscopy

Biofilms are the preferred habitat of microorganisms on living and artificial surfaces. Biofilm-related infections, such as infections of medical implants, are difficult to treat, and due to a reduced cultivability of the included bacteria, difficult to diagnose. Therefore, it is highly important to rapidly identify and investigate biofilms on implant surfaces, e.g., during surgery. In this study, we present fiber-probe-based Raman spectroscopy with an excitation wavelength of 785 nm, which was applied to investigate six different pathogen species involved in biofilm-related infections. Biofilms were cultivated in a drip flow reactor, which can model a biofilm growth environment. The signals collected from a fiber probe allowed us to collect Raman spectra not only from the embedded bacterial and yeast cells but also the surrounding extracellular polymeric substance matrix. This information was used in a classification model. The model consists of a principal component analysis in combination with linear discriminant analysis and was examined by applying a leave-one-batch-out cross-validation. This model achieved a classification accuracy of 93.8%. In addition, the identification accuracy increased up to 97.5% when clinical strains were used for identification. A fiber-probe-based Raman spectroscopy method combined with a chemometric analysis might therefore serve as a fast, accurate, and portable strategy for the species identification of biofilm-related infections, e.g., during surgical procedures.

Sleep Disordered Breathing and Recurrent Tonsillitis Are Associated With Polymicrobial Bacterial Biofilm Infections Suggesting a Role for Anti-Biofilm Therapies

Background

The underlying pathogenesis of pediatric obstructive sleep disordered breathing (SDB) and recurrent tonsillitis (RT) are poorly understood but need to be elucidated to develop less invasive treatment and prevention strategies.

Methods

Children aged between 1- and 16-years undergoing adenoidectomy, tonsillectomy or adenotonsillectomy for SDB (n=40), RT alone (n=18), or both SDB and RT (SDB+RT) (n=17) were recruited with age-matched healthy controls (n=33). Total bacterial load and species-specific densities of nontypeable Haemophilus influenzae (NTHi), Staphylococcus aureus, Streptococcus pyogenes, Streptococcus pneumoniae and Moraxella catarrhalis were measured by qPCR in nasopharyngeal swabs, oropharyngeal swabs, adenoid and tonsillar tissue from children with SDB, SDB+RT and RT, and in naso- and oro- pharyngeal swabs from healthy children. A subset of tonsil biopsies were examined for biofilms using 16S rRNA FISH (n=3/group).

Results

The 5 bacterial species were detected in naso- and oro- pharyngeal samples from all children. These species were frequently detected in adenotonsillar tissue (except S. aureus, which was absent in adenoids) from children with SDB, SDB+RT and RT. NTHi and S. aureus were observed in tonsils from 66.7-88.2% and 33.3-58.8% of children respectively. Similar total and species-specific bacterial densities were observed in adenotonsillar tissue from children with SDB, SDB+RT or RT. Nasopharyngeal and oropharyngeal swabs were more likely to have multiple bacterial species co-detected than adenotonsillar tissue where one or two targeted species predominated. Polymicrobial biofilms and intracellular bacteria were observed in tonsils from children with adenotonsillar disease.

Conclusions

Antimicrobials, particularly anti-biofilm therapies, may be a strategy for managing children with SDB.

The Role of luxS in the Middle Ear Streptococcus pneumoniae Isolate 947

The LuxS protein, encoded by luxS, is required for the production of autoinducer 2 (AI-2) in Streptococcus pneumoniae. The AI-2 molecule serves as a quorum sensing signal, and thus regulates cellular processes such as carbohydrate utilisation and biofilm formation, as well as impacting virulence. The role of luxS in S. pneumoniae biology and lifestyle has been predominantly assessed in the laboratory strain D39. However, as biofilm formation, which is regulated by luxS, is critical for the ability of S. pneumoniae to cause otitis media, we investigated the role of luxS in a middle ear isolate, strain 947. Our results identified luxS to have a role in prevention of S. pneumoniae transition from colonisation of the nasopharynx to the ear, and in facilitating adherence to host epithelial cells.

Nontypeable Haemophilus influenzae Redox Recycling of Protein Thiols Promotes Resistance to Oxidative Killing and Bacterial Survival in Biofilms in a Smoke-Related Infection Model

Smoke exposure is a risk factor for community-acquired pneumonia, which is typically caused by host-adapted airway opportunists like nontypeable Haemophilus influenzae (NTHi). Genomic analyses of NTHi revealed homologs of enzymes with predicted roles in reduction of protein thiols, which can have key roles in oxidant resistance. Using a clinical NTHi isolate (NTHi 7P49H1), we generated isogenic mutants in which homologs of glutathione reductase (open reading frame NTHI 0251), thioredoxin-dependent thiol peroxidase (NTHI 0361), thiol peroxidase (NTHI 0907), thioredoxin reductase (NTHI 1327), and glutaredoxin/peroxiredoxin (NTHI 0705) were insertionally inactivated. Bacterial protein analyses revealed that protein oxidation after hydrogen peroxide treatment was elevated in all the mutant strains. Similarly, each of these mutants was less resistant to oxidative killing than the parental strain; these phenotypes were reversed by genetic complementation. Analysis of biofilm communities formed by the parental and mutant strains showed reduction in overall biofilm thickness and density and significant sensitization of bacteria within the biofilm structure to oxidative killing. Experimental respiratory infection of smoke-exposed mice with NTHi 7P49H1 showed significantly increased bacterial counts compared to control mice. Immunofluorescent staining of lung tissues showed NTHi communities on lung mucosae, interspersed with neutrophil extracellular traps; these bacteria had transcript profiles consistent with NTHi biofilms. In contrast, infection with the panel of NTHi mutants showed a significant decrease in bacterial load. Comparable results were observed in bactericidal assays with neutrophil extracellular traps in vitro. Thus, we conclude that thiol-mediated redox homeostasis is a determinant of persistence of NTHi within biofilm communities.

IMPORTANCE Chronic bacterial respiratory infections are a significant problem for smoke-exposed individuals, especially those with chronic obstructive pulmonary disease (COPD). These infections often persist despite antibiotic use. Thus, the bacteria remain and contribute to the development of inflammation and other respiratory problems. Respiratory bacteria often form biofilms within the lungs; during growth in a biofilm, their antibiotic and oxidative stress resistance is incredibly heightened. It is well documented that redox homeostasis genes are upregulated during this phase of growth. Many common respiratory pathogens, such as NTHi and Streptococcus pneumoniae, are reliant on scavenging from the host the necessary components they need to maintain these redox systems. This work begins to lay the foundation for exploiting this requirement and thiol redox homeostasis pathways of these bacteria as a therapeutic target for managing chronic respiratory bacterial infections, which are resistant to traditional antibiotic treatments alone.

Gene expression analysis reveals immune and metabolic candidate pathways in the pathogenesis of chronic otitis media

OBJECTIVES

Chronic otitis media (COM) is a common disease and causes significant hearing impairment in many adults. Our study aimed to investigate the immune response in COM adult patients through RNA sequencing.

METHODS

In this study, we enrolled four adult COM patients and five healthy controls (HCs) to analyze and compare the mRNA signatures in their peripheral blood mononuclear cells (PBMCs). Gene Ontology functional enrichment and Kyoto Encyclopedia of Genes and Genomes pathway analyses were performed on the differentially expressed genes between the COM patients and the HCs. Furthermore, the immune cell proportions of the two groups were estimated by CIBERSORT. The GSE125532, GSE27990, and GSE23140 gene expression profiles were also retrieved and analyzed for comparison with our results.

RESULTS

Many immune pathways and genes were upregulated in the COM patients, including the IL-17 pathway and NLRP3. Monocytes and macrophages increased (P=0.005 and P=0.033, respectively), and the CD8+ T cells decreased (P=0.033) in the COM patients compared to the HCs. The COM patients' signatures also reflected a hypoxic state.

CONCLUSIONS

Our findings emphasized the roles of several immune pathways and a hypoxic state in interpreting host responses during COM, and may enable the development of novel therapeutic tools for the disease.

Identification of the Bacterial Pathogens in Children with Otitis Media: A Study in the Northwestern Portuguese District of Braga

Understanding the bacterial etiology of otitis media (OM) is important when designing and evaluating the best course of treatment. This study analyzed middle ear fluid (MEF) and nasopharynx (NP) samples collected from 49 children with OM undergoing myringotomy in the northwestern Portuguese district of Braga. A correlation between species in the NP and MEF was observed following pathogen detection by culture and quantitative polymerase chain reaction (qPCR) methods. Bacterial identification using culturing methods showed that Moraxella catarrhalis was the most representative in NP and MEF, followed by Streptococcus pneumoniae. However, qPCR of MEF showed a higher prevalence (61%) of Haemophilus influenzae. S. pneumoniae was not the most frequently identified species, but it still remains one of the leading causes of OM in this region despite 93.9% of the children being vaccinated with the pneumococcal conjugate vaccine. Furthermore, 46% of the samples analyzed by qPCR identified more than two bacterial species. M. catarrhalis and S. pneumoniae were the most frequent combination identified in NP and MEF samples by culturing methods. Additionally, a few NP and MEF samples simultaneously presented the three main otopathogens. These results point out that polymicrobial infections play an important role in OM. Further studies characterizing the serotypes of the strains isolated, their resistance profile, and their biofilm forming ability would help in the development of more targeted strategies against otitis media.