Longitudinal analysis of sinus microbiota post endoscopic surgery in patients with cystic fibrosis and chronic rhinosinusitis: a pilot study.

BACKGROUND: Cystic fibrosis is a debilitating, autosomal recessive disease which results in chronic upper and lower airway infection and inflammation. In this study, four adult patients presenting with cystic fibrosis and chronic rhinosinusitis were recruited. Culture and molecular techniques were employed to evaluate changes in microbial profiles, host gene expression and antimicrobial resistance (AMR) in the upper respiratory tract over time. METHODS: Swab samples from the sinonasal cavity were collected at the time of surgery and at follow-up clinics at regular time intervals for up to 18 months. Nucleic acids were extracted, and DNA amplicon sequencing was applied to describe bacterial and fungal composition. In parallel, RNA was used to evaluate the expression of 17 AMR genes and two inflammatory markers (interleukins 6 and 8) using custom qPCR array cards. Molecular results were compared with routine sinus and sputum culture reports within each patient. RESULTS: Bacterial amplicon sequencing and swab culture reports from the sinonasal cavity were mostly congruent and relatively stable for each patient across time. The predominant species detected in patients P02 and P04 were Pseudomonas aeruginosa, Staphylococcus aureus in patient P03, and a mixture of Enterobacter and S. aureus in patient P01. Fungal profiles were variable and less subject specific than bacterial communities. Increased expressions of interleukins 6 and 8 were observed in all patients throughout the sampling period compared with other measured genes. The most prevalent AMR gene detected was ampC. However, the prevalence of AMR gene expression was low in all patient samples across varying time-points. CONCLUSIONS: We observed a surprising degree of stability of sinonasal microbial composition, and inflammatory and AMR gene expression across all patients post sinus surgery.

Oral microbial influences on oral mucositis during radiotherapy treatment of head and neck cancer.

PURPOSE: Oral mucositis (OM) remains a significant complication developed by many patients undergoing radiotherapy (RT) to the head and neck region. Emerging data suggest oral microbes may contribute to the onset and severity of this acute side effect. METHODS: In this study, saliva and oral swabs from head and neck cancer patients undergoing RT were collected. We employed molecular microbiological techniques to study the bacterial communities present in saliva, and both the bacterial and fungal communities present on the buccal mucosa and lateral tongue. Changes in microbiota composition with increasing radiation dose and the presence of mucositis were examined. RESULTS: The data suggest that the salivary microbiota remain stable during RT and are consistently dominated by Streptococcus, Prevotella, Fusobacterium and Granulicatella. Obligate and facultative anaerobic Gram-negative bacilli (GNB) Bacteroidales G2, Capnocytophaga, Eikenella, Mycoplasma and Sneathia, as well as anaerobic GNB in the periopathogenic genera Porphyromonas and Tannerella, were all positively correlated with ≥ grade 2 OM. Significant increases in the relative abundances of Bacteroidales G2, Fusobacterium and Sneathia were identified in buccal mucosa swabs at sites of ≥ grade 2 OM (p < 0.05). Furthermore, the abundance of several GNB (Fusobacterium, Haemophilus, Tannerella, Porphyromonas and Eikenella) on the buccal mucosa may influence patient susceptibility to developing OM. Candida was widely detected in buccal mucosa swabs, regardless of mucositis status. CONCLUSIONS: Our findings support previously hypothesized associations between oral health and the pathogenesis of OM, highlighting the importance of oral health interventions for head and neck cancer patients.

Oral antibiotics used in the treatment of chronic rhinosinusitis have limited penetration into the sinonasal mucosa: a randomized trial.

Despite the widespread prescription of antibiotics for patients with chronic rhinosinusitis (CRS), the extent to which drug distribution to the sinonasal mucosa occurs remains largely undefined. Twenty subjects undergoing functional endoscopic sinus surgery (FESS) for CRS were randomized to one of two groups: 1) doxycycline (100 mg daily for seven days) 2) roxithromycin (300 mg daily for seven days). Drug levels were measured using liquid chromatography-tandem mass spectrometry in sinonasal mucus, sinonasal tissues and serum at steady state. Doxycycline concentrations measured in the mucus were significantly lower compared to that in the serum (mean mucus/serum ratio = 0.16, p < 0.001) and the tissue (mean mucus/tissue ratio = 0.18, p < 0.0001). Roxithromycin concentrations in the mucus were also significantly lower compared to that in the serum (mean mucus/serum ratio = 0.37, p = 0.002) and the tissue (mean mucus/tissue ratio = 0.60, p < 0.001). Although the efficacy of doxycycline and roxithromycin in sinonasal mucus in vivo cannot be predicted solely from reported minimum inhibitory concentrations, given the added complexity of bacterial biofilm antimicrobial tolerance, these results suggest that low mucosal penetration of antibiotics may be one of the factors contributing to the limited efficacy of these agents in the treatment of CRS.

Chronic Rhinosinusitis and the Evolving Understanding of Microbial Ecology in Chronic Inflammatory Mucosal Disease.

Chronic rhinosinusitis (CRS) encompasses a heterogeneous group of debilitating chronic inflammatory sinonasal diseases. Despite considerable research, the etiology of CRS remains poorly understood, and debate on potential roles of microbial communities is unresolved. Modern culture-independent (molecular) techniques have vastly improved our understanding of the microbiology of the human body. Recent studies that better capture the full complexity of the microbial communities associated with CRS reintroduce the possible importance of the microbiota either as a direct driver of disease or as being potentially involved in its exacerbation. This review presents a comprehensive discussion of the current understanding of bacterial, fungal, and viral associations with CRS, with a specific focus on the transition to the new perspective offered in recent years by modern technology in microbiological research. Clinical implications of this new perspective, including the role of antimicrobials, are discussed in depth. While principally framed within the context of CRS, this discussion also provides an analogue for reframing our understanding of many similarly complex and poorly understood chronic inflammatory diseases for which roles of microbes have been suggested but specific mechanisms of disease remain unclear. Finally, further technological advancements on the horizon, and current pressing questions for CRS microbiological research, are considered.

Bacterial community collapse: a meta-analysis of the sinonasal microbiota in chronic rhinosinusitis.

Chronic rhinosinusitis (CRS) is a common, debilitating condition characterized by long-term inflammation of the nasal cavity and paranasal sinuses. The role of the sinonasal bacteria in CRS is unclear. We conducted a meta-analysis combining and reanalysing published bacterial 16S rRNA sequence data to explore differences in sinonasal bacterial community composition and predicted function between healthy and CRS affected subjects. The results identify the most abundant bacteria across all subjects as Staphylococcus, Propionibacterium, Corynebacterium, Streptococcus and an unclassified lineage of Actinobacteria. The meta-analysis results suggest that the bacterial community associated with CRS patients is dysbiotic and ecological networks fostering healthy communities are fragmented. Increased dispersion of bacterial communities, significantly lower bacterial diversity, and increased abundance of members of the genus Corynebacterium are associated with CRS. Increased relative abundance and diversity of other members belonging to the phylum Actinobacteria and members from the genera Propionibacterium differentiated healthy sinuses from those that were chronically inflamed. Removal of Burkholderia and Propionibacterium phylotypes from the healthy community dataset was correlated with a significant increase in network fragmentation. This meta-analysis highlights the potential importance of the genera Burkholderia and Propionibacterium as gatekeepers, whose presence may be important in maintaining a stable sinonasal bacterial community.

Molecular Microbiological Profile of Chronic Suppurative Otitis Media.

Chronic suppurative otitis media (CSOM) presents with purulent otorrhea (ear discharge), is characterized by chronic inflammation of the middle ear and mastoid cavity, and contributes to a significant disease burden worldwide. Current antibiotic therapy is guided by swab culture results. In the absence of detailed molecular microbiology studies of CSOM patients, our current understanding of the microbiota of CSOM (and indeed of the healthy ear) remains incomplete. In this prospective study, 24 patients with CSOM were recruited, along with 22 healthy controls. Culture-based techniques and 16S rRNA gene amplicon sequencing were used to profile the bacterial community for each patient. Comparisons between patients with and without cholesteatoma in the middle ear and mastoid cavity were also made. A major finding was that the middle ear of many healthy controls was not sterile, which is contradictory to the results of previous studies. However, sequencing data showed that Staphylococcus aureus, along with a range of other Gram-positive and Gram-negative organisms, were present in all subgroups of CSOM and healthy controls. Large interpatient variability in the microbiota was observed within each subgroup of CSOM and controls, and there was no bacterial community "signature" which was characteristic of either health or disease. Comparisons of the culture results with the molecular data show that culture-based techniques underestimate the diversity of bacteria found within the ear. This study reports the first detailed examination of bacterial profiles of the ear in healthy controls and patients with CSOM.

Microbial community structure in the gut of the New Zealand insect Auckland tree weta (Hemideina thoracica).

The endemic New Zealand weta is an enigmatic insect. Although the insect is well known by its distinctive name, considerable size, and morphology, many basic aspects of weta biology remain unknown. Here, we employed cultivation-independent enumeration techniques and rRNA gene sequencing to investigate the gut microbiota of the Auckland tree weta (Hemideina thoracica). Fluorescence in situ hybridisation performed on different sections of the gut revealed a bacterial community of fluctuating density, while rRNA gene-targeted amplicon pyrosequencing revealed the presence of a microbial community containing high bacterial diversity, but an apparent absence of archaea. Bacteria were further studied using full-length 16S rRNA gene sequences, with statistical testing of bacterial community membership against publicly available termite- and cockroach-derived sequences, revealing that the weta gut microbiota is similar to that of cockroaches. These data represent the first analysis of the weta microbiota and provide initial insights into the potential function of these microorganisms.

Successional development of biofilms in moving bed biofilm reactor (MBBR) systems treating municipal wastewater.

Biofilm-based technologies, such as moving bed biofilm reactor (MBBR) systems, are widely used to treat wastewater. Biofilm development is important for MBBR systems as much of the microbial biomass is retained within reactors as biofilm on suspended carriers. Little is known about this process of biofilm development and the microorganisms upon which MBBRs rely. We documented successional changes in microbial communities as biofilms established in two full-scale MBBR systems treating municipal wastewater over two seasons. 16S rRNA gene-targeted pyrosequencing and clone libraries were used to describe microbial communities. These data indicate a successional process that commences with the establishment of an aerobic community dominated by Gammaproteobacteria (up to 52 % of sequences). Over time, this community shifts towards dominance by putatively anaerobic organisms including Deltaproteobacteria and Clostridiales. Significant differences were observed between the two wastewater treatment plants (WWTPs), mostly due to a large number of sequences (up to 55 %) representing Epsilonproteobacteria (mostly Arcobacter) at one site. Archaea in young biofilms included several lineages of Euryarchaeota and Crenarchaeota. In contrast, the mature biofilm consisted entirely of Methanosarcinaceae (Euryarchaeota). This study provides new insights into the community structure of developing biofilms at full-scale WWTPs and provides the basis for optimizing MBBR start-up and operational parameters.

dsrAB-based analysis of sulphate-reducing bacteria in moving bed biofilm reactor (MBBR) wastewater treatment plants.

Sulphate-reducing bacteria (SRB) are important members of the sulphur cycle in wastewater treatment plants (WWTPs). In this study, we investigate the diversity and activity of SRB within the developing and established biofilm of two moving bed biofilm reactor (MBBR) systems treating municipal wastewater in New Zealand. The larger of the two WWTPs (Moa Point) generates high levels of sulphide relative to the smaller Karori plant. Clone libraries of the dissimilatory (bi)sulphite reductase (dsrAB) genes and quantitative real-time PCR targeting dsrA transcripts were used to compare SRB communities between the two WWTPs. Desulfobulbus (35-53 % of total SRB sequences) and genera belonging to the family Desulfobacteraceae (27-41 %) dominated the SRB fraction of the developing biofilm on deployed plastic carriers at both sites, whereas Desulfovibrio and Desulfomicrobium were exclusively found at Moa Point. In contrast, the established biofilms from resident MBBR carriers were largely dominated by Desulfomonile tiedjei-like organisms (58-100 % of SRB sequences). The relative transcript abundance of dsrA genes (signifying active SRBs) increased with biofilm weight yet remained low overall, even in the mature biofilm stage. Our results indicate that although SRB are both present and active in the microbial community at both MBBR study sites, differences in the availability of sulphate may be contributing to the observed differences in sulphide production at these two plants.

Paired qualitative and quantitative analysis of bacterial microcolonies in the tonsils of patients with tonsillar hyperplasia.

The discovery of bacterial microcolonies in tonsillar tissue of patients with tonsillar hyperplasia has raised the question of their role in provoking the local immune response. Tonsils collected from patients undergoing tonsillectomy were stained for three clinically relevant bacterial taxa and lymphocytes. The bacterial composition and abundance of microcolonies was investigated using a combination of laser-microdissection, amplicon sequencing and Droplet Digital polymerase chain reaction. Microcolonies were detected in most samples (32/35) with a high prevalence of Haemophilus influenzae (78% of samples). B and T cell lymphocytes were significantly higher in the epithelium adjacent to microcolonies compared to epithelium distal to microcolonies. Furthermore, significant positive and negative correlations were identified between bacterial taxa and lymphocytes. Genus Streptococcus, which includes Group A Streptococcus (traditionally described as the main pathogen of tonsillar hyperplasia), was found in low abundance in this study. These results suggest other potential pathogens may be involved in stimulating the local immune response leading to tonsillar hyperplasia.

Polymyxin B and ethylenediaminetetraacetic acid act synergistically against Pseudomonas aeruginosa and Staphylococcus aureus.

Polymyxin B and ethylenediaminetetraacetic acid are antimicrobials possessing antibiofilm activity. They act by displacement and chelation, respectively, of divalent cations in bacterial membranes and may therefore act synergistically when applied in combination. If so, this combination of agents may be useful for the treatment of diseases like cystic fibrosis (CF), in which biofilms are present on the respiratory epithelium. We used checkerboard assays to investigate the synergy between these agents using reference strains Pseudomonas aeruginosa ATCC 27853 and Staphylococcus aureus ATCC 6538 in planktonic form. We then determined the efficacy of each agent against biofilms of both species grown on 96-pin lids and proceeded to combination testing against the P. aeruginosa reference strain and 10 clinical isolates from patients with CF. Synergism was observed for planktonic forms of both species and for biofilms of P. aeruginosa. The susceptibility of biofilms of P. aeruginosa clinical isolates to these agents was variable compared to the laboratory reference strain. This combination of agents may be useful in the management of biofilm-associated conditions, particularly those amenable to topical therapies. These results provide a basis upon which the antimicrobial and antibiofilm efficacy of preparations containing these agents may be enhanced.IMPORTANCEBacteria living in biofilms produce a protective matrix which makes them difficult to kill. Patients with severe respiratory disease often have biofilms. Polymyxin B is an antibiotic commonly used in topical medications, such as eye drops and nasal sprays. Ethylenediaminetetraacetic acid (EDTA) is used widely as a preservative in medication but also has antimicrobial properties. It has been hypothesized that Polymyxin B and EDTA could have a synergistic relationship: when used in combination their antimicrobial effect is enhanced. Here, we evaluated the levels at which Polymyxin B and EDTA work together to kill common pathogens Pseudomonas aeruginosa and Staphylococcus aureus. We found that Polymyxin B and EDTA were synergistic. This synergy may be useful in the management of planktonic infection with P. aeruginosa and S. aureus, or biofilm infection with P. aeruginosa. This synergy may be beneficial in the treatment of respiratory biofilms, in which P. aeruginosa biofilms are common.

Current evidence of biofilms in chronic rhinosinusitis- a microbiological perspective.

INTRODUCTION: Chronic rhinosinusitis (CRS) is characterized by inflammation of the paranasal sinus mucosa persisting for more than 12 weeks. This condition is associated with reduced quality-of-life and causes a high direct and indirect economic burden. Several pathogenic factors have been attributed to CRS, including bacterial and fungal biofilms on the sinonasal mucosa. Biofilms are well-established contributors to recalcitrance to treatment in other chronic inflammatory mucosal conditions such as cystic fibrosis and otitis media. AREAS COVERED: This review will present an overview of the role of biofilms in CRS, including the evidence for biofilms being present on the sinonasal mucosa and their implications for disease severity. Furthermore, the interactions between biofilms and host-mediated immune factors are explored. EXPERT OPINION: The eradication of biofilms has been a focus of research shortly after their recognition as a cause of disease. The currently available methodologies for identifying biofilms on mucosal surfaces are not sufficiently well-developed to be used in a clinical setting. A more accurate, cheaper, faster approach for biofilm detection is necessary, and molecular techniques may provide the possibility for this.

Bioinformatic Approaches for Describing the Oral Microbiota.

Cultivation-independent (molecular) analysis of the oral microbiota can provide a comprehensive picture of microbial community composition, yet there is an at-times bewildering array of approaches that can be employed. This chapter introduces some of the key considerations when undertaking microbiota research and describes two alternative bioinformatic pipelines for conducting such studies. The descriptions are based on analysis of bacterial 16S ribosomal RNA gene sequences, but can be easily adapted for analysis of other microbial taxa such as fungi.

Bacterial communities in the nasal passage of postviral olfactory dysfunction patients.

KEY POINTS: Bacterial composition is uniform in the sinuses of postviral olfactory dysfunction patients. Significant reduction of genus Corynebacterium in PVOD patients compared to controls.

In vitro Nasodine Can be an Effective Antibiofilm Agent for Biofilms that May Cause CRS.

OBJECTIVES: Bacterial biofilms on the sinonasal mucosa, especially biofilms of Staphylococcus aureus, are associated with greater severity and recalcitrance of chronic rhinosinusitis (CRS). There are few, if any, antibiofilm agents suitable for sinonasal application available for the management of this problem. Nasodine® Nasal Spray (Nasodine) is a 0.5% povidone-iodine-based formulation that has been developed for sinonasal application. We investigated the antibiofilm efficacy of Nasodine to determine whether it may be a candidate for the treatment of biofilm-associated CRS. METHODS: Biofilms of S. aureus ATCC 6538 were grown in vitro using the Centers for Disease Control biofilm reactor. Intact biofilms were treated by immersion in 0.9% saline (control), half concentration Nasodine, or full concentration Nasodine for between 5 min and 6 h. Further biofilm cells were dispersed into suspension then treated for between 30 s and 5 min. Surviving bacteria were then enumerated by culture and counting colonies, and the log10 reduction in viable bacteria was compared with control. RESULTS: Nasodine demonstrated time and concentration-dependent bacterial killing against intact biofilm. Statistically significant reductions in viable bacteria from intact biofilms were seen with exposures as brief as 5 min. Nasodine consistently eradicated dispersed biofilm within 1 min. CONCLUSION: Nasodine is highly active against biofilms of S. aureus ATCC 6538 in vitro. Biofilm killing is impeded by the presence of the intact biofilm structure. LAY SUMMARY: In chronic rhinosinusitis (CRS), bacterial communities called biofilms are associated with more severe inflammation. An iodine-based nasal spray called Nasodine almost completely eradicates bacterial biofilms after 6 h of exposure. Nasodine may be useful for treating CRS. Laryngoscope, 133:2490-2495, 2023.

Genome-wide association study of brain biochemical phenotypes reveals distinct genetic architecture of Alzheimer's disease related proteins.

BACKGROUND: Alzheimer's disease (AD) is neuropathologically characterized by amyloid-beta (Aß) plaques and neurofibrillary tangles. The main protein components of these hallmarks include Aß40, Aß42, tau, phosphor-tau, and APOE. We hypothesize that genetic variants influence the levels and solubility of these AD-related proteins in the brain; identifying these may provide key insights into disease pathogenesis. METHODS: Genome-wide genotypes were collected from 441 AD cases, imputed to the haplotype reference consortium (HRC) panel, and filtered for quality and frequency. Temporal cortex levels of five AD-related proteins from three fractions, buffer-soluble (TBS), detergent-soluble (Triton-X = TX), and insoluble (Formic acid = FA), were available for these same individuals. Variants were tested for association with each quantitative biochemical measure using linear regression, and GSA-SNP2 was used to identify enriched Gene Ontology (GO) terms. Implicated variants and genes were further assessed for association with other relevant variables. RESULTS: We identified genome-wide significant associations at seven novel loci and the APOE locus. Genes and variants at these loci also associate with multiple AD-related measures, regulate gene expression, have cell-type specific enrichment, and roles in brain health and other neuropsychiatric diseases. Pathway analysis identified significant enrichment of shared and distinct biological pathways. CONCLUSIONS: Although all biochemical measures tested reflect proteins core to AD pathology, our results strongly suggest that each have unique genetic architecture and biological pathways that influence their specific biochemical states in the brain. Our novel approach of deep brain biochemical endophenotype GWAS has implications for pathophysiology of proteostasis in AD that can guide therapeutic discovery efforts focused on these proteins.

Microbial community composition and dynamics of moving bed biofilm reactor systems treating municipal sewage.

Moving bed biofilm reactor (MBBR) systems are increasingly used for municipal and industrial wastewater treatment, yet in contrast to activated sludge (AS) systems, little is known about their constituent microbial communities. This study investigated the community composition of two municipal MBBR wastewater treatment plants (WWTPs) in Wellington, New Zealand. Monthly samples comprising biofilm and suspended biomass were collected over a 12-month period. Bacterial and archaeal community composition was determined using a full-cycle community approach, including analysis of 16S rRNA gene libraries, fluorescence in situ hybridization (FISH) and automated ribosomal intergenic spacer analysis (ARISA). Differences in microbial community structure and abundance were observed between the two WWTPs and between biofilm and suspended biomass. Biofilms from both plants were dominated by Clostridia and sulfate-reducing members of the Deltaproteobacteria (SRBs). FISH analyses indicated morphological differences in the Deltaproteobacteria detected at the two plants and also revealed distinctive clustering between SRBs and members of the Methanosarcinales, which were the only Archaea detected and were present in low abundance (<5%). Biovolume estimates of the SRBs were higher in biofilm samples from one of the WWTPs which receives both domestic and industrial waste and is influenced by seawater infiltration. The suspended communities from both plants were diverse and dominated by aerobic members of the Gammaproteobacteria and Betaproteobacteria. This study represents the first detailed analysis of microbial communities in full-scale MBBR systems and indicates that this process selects for distinctive biofilm and planktonic communities, both of which differ from those found in conventional AS systems.

The histological and microbiological characteristics of bacterial microcolonies in paediatric tonsillar hyperplasia.

INTRODUCTION: Paediatric tonsillar hyperplasia (TH) is associated with a spectrum of presentations ranging from recurrent tonsillitis (RT) to sleep-disordered breathing (SDB). The underlying pathogenesis of tonsillar hyperplasia remains poorly understood. Previous studies have implicated bacterial microcolonies as targets of host inflammatory cells and as a potential driver of the chronic inflammation seen in TH. The role of atopy in tonsillar hyperplasia is also largely unknown. In this study, we aimed to determine the allergic responses and microbial factors that may influence TH in children. MATERIALS AND METHODS: Paired tonsils and a serum sample were collected from 21 children undergoing tonsillectomy for RT or SDB in the Auckland region. The disposition of immunoglobulin isotypes (IgG, A, M and E) and local inflammatory cells on histological sections of tonsil tissue were determined using immunohistochemistry techniques. Aeroallergen specific IgE (sIgE) and Staphylococcal enterotoxin C specific IgE (SEC-specific IgE) were measured in serum and tonsil tissue using the ImmunoCAP® system. Finally, tonsil bacterial microcolonies were then excised from histological slides using laser microdissection techniques, before undergoing bacterial and fungal amplicon sequencing. RESULTS: There were no significant differences in any of the measured variables between children with RT and SDB symptoms. IgE staining was not associated with increased levels of mast cells, leukocytes or plasma cells. However, sIgE positivity was more frequently found in local tissue than in serum (p = 0.025). A significant association was observed between tissue sIgE levels and tissue SEC-specific IgE levels (r2 = 0.95, p = 0.0001). The most abundant bacterial and fungal genera identified in the microcolonies were Fusobacterium, Sphingomonas, Porphyromonas, Prevotella and Malassezia. DISCUSSION: These results suggest that there is a local IgE response in children with TH. Local IgE production is unrelated to systemic atopy and may play a key role in the pathogenesis of TH. This is the first study to determine the microbial composition of microcolonies in tonsil tissue. These findings enhance current understanding of the microbiology of tonsils in children with TH and have important implications for antibiotic strategies.

Topical Antibiofilm Agents With Potential Utility in the Treatment of Chronic Rhinosinusitis: A Narrative Review.

The role of bacterial biofilms in chronic and recalcitrant diseases is widely appreciated, and the treatment of biofilm infection is an increasingly important area of research. Chronic rhinosinusitis (CRS) is a complex disease associated with sinonasal dysbiosis and the presence of bacterial biofilms. While most biofilm-related diseases are associated with highly persistent but relatively less severe inflammation, the presence of biofilms in CRS is associated with greater severity of inflammation and recalcitrance despite appropriate treatment. Oral antibiotics are commonly used to treat CRS but they are often ineffective, due to poor penetration of the sinonasal mucosa and the inherently antibiotic resistant nature of bacteria in biofilms. Topical non-antibiotic antibiofilm agents may prove more effective, but few such agents are available for sinonasal application. We review compounds with antibiofilm activity that may be useful for treating biofilm-associated CRS, including halogen-based compounds, quaternary ammonium compounds and derivatives, biguanides, antimicrobial peptides, chelating agents and natural products. These include preparations that are currently available and those still in development. For each compound, antibiofilm efficacy, mechanism of action, and toxicity as it relates to sinonasal application are summarised. We highlight the antibiofilm agents that we believe hold the greatest promise for the treatment of biofilm-associated CRS in order to inform future research on the management of this difficult condition.

The Effect of Amoxicillin with Clavulanate on the Microbiota of Tonsillar Tissue in Disease: a Randomized Control Trial.

Despite antibiotics being the primary medical treatment for recurrent tonsillitis, the impact of antibiotics on the tonsillar microbiome is not well understood. This study aimed to determine the effect of amoxicillin with clavulanate on the composition and quantity of bacteria in the tonsils of children with recurrent tonsillitis. A multicenter randomized clinical trial in Auckland, New Zealand was undertaken between August 1, 2017, and June 30, 2018. Sixty children undergoing tonsillectomy for the indication of recurrent tonsillitis were recruited for this study. Following random allocation, 30 participants were prescribed amoxicillin with clavulanate for the week before surgery. The remaining 30 received no antibiotics. Immediately following surgery, the crypts of the right and left tonsils were swabbed. Bacterial 16S rRNA gene-targeted amplicon sequencing and histological techniques were utilized. In the control group, there were significantly higher relative abundances of Haemophilus, Streptococcus, Neisseria, and Porphyromonas. Members from the genera Fusobacterium and Treponema were found to be significantly more abundant in the antibiotic group. There were no significant differences in the absolute quantities of bacteria between the groups. Microscopic examination found fewer bacterial microcolonies present in the tonsillar crypts of participants in the antibiotic group. Streptococcus pyogenes was not present in these bacterial microcolonies. These results suggest that a single course of antibiotics has a significant impact on the tonsil microbiota composition. The duration of this effect and the effect that the altered microbiome has on the course of the condition need to be determined. IMPORTANCE Several studies have identified the presence of multiple pathogenic bacteria in hyperplastic adenoids and palatine tonsils. However, there are currently no studies that utilize this technology to investigate the effect of oral antibiotics in children with recurrent tonsillitis on the tonsillar microbiome. This is the first study to investigate the effect of antibiotics on the microbiome of tonsillar tissue in children with recurrent tonsillitis using molecular techniques. This study has shown that participants who received amoxicillin with clavulanate immediately before tonsillectomy had a significantly reduced number of bacterial taxa commonly associated with recurrent tonsillitis, as well as the number of bacterial microcolonies observed in the tonsillar crypts. This novel finding suggests that either the effect of antibiotics is not sustained or that they are not an effective treatment for recurrent tonsillitis.