Targeted imaging modality selection for bacterial biofilms in chronic rhinosinusitis

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.

International consensus statement on allergy and rhinology: rhinosinusitis 2021

I.

EXECUTIVE SUMMARY

BACKGROUND: The 5 years since the publication of the first International Consensus Statement on Allergy and Rhinology: Rhinosinusitis (ICAR-RS) has witnessed foundational progress in our understanding and treatment of rhinologic disease. These advances are reflected within the more than 40 new topics covered within the ICAR-RS-2021 as well as updates to the original 140 topics. This executive summary consolidates the evidence-based findings of the document.

METHODS

ICAR-RS presents over 180 topics in the forms of evidence-based reviews with recommendations (EBRRs), evidence-based reviews, and literature reviews. The highest grade structured recommendations of the EBRR sections are summarized in this executive summary.

RESULTS

ICAR-RS-2021 covers 22 topics regarding the medical management of RS, which are grade A/B and are presented in the executive summary. Additionally, 4 topics regarding the surgical management of RS are grade A/B and are presented in the executive summary. Finally, a comprehensive evidence-based management algorithm is provided.

CONCLUSION

This ICAR-RS-2021 executive summary provides a compilation of the evidence-based recommendations for medical and surgical treatment of the most common forms of RS.

Staphylococcus aureus internalization in mast cells in nasal polyps: Characterization of interactions and potential mechanisms

BACKGROUND

Chronic rhinosinusitis (CRS) with nasal polyps is a common chronic condition. The exact cause of nasal polyps remains unknown. Recently, we made the novel observation of intracellular localization of Staphylococcus aureus within mast cells in nasal polyps.

OBJECTIVE

This follow-up study aimed to further characterize interactions between S aureus and mast cells in this setting and elucidate potential internalization mechanisms with particular emphasis on the role of staphylococcal enterotoxin B (SEB).

METHODS

A prospective study was performed using an explant tissue model with ex vivo inferior turbinate mucosa obtained from patients with chronic rhinosinusitis with nasal polyps (n = 7) and patients without CRS (n = 5). Immunohistochemistry was used to characterize S aureus uptake into mast cells and investigate the effects of SEB on this process. An in vitro cell-culture model was used to investigate mast cell-S aureus interactions by using a combination of fluorescent in situ hybridization, confocal laser scanning microscopy, scanning electron microscopy, transmission electron microscopy, and proliferation assays.

RESULTS

S aureus was captured by extracellular traps and entered mast cells through phagocytosis. Proliferating intracellular S aureus led to the expansion and eventual rupture of mast cells, resulting in release of viable S aureus into the extracellular space. The presence of SEB appeared to promote internalization of S aureus into mast cells.

CONCLUSION

This study provides new insights into the interactions between S aureus and mast cells, including the internalization process, and demonstrates a prominent role for SEB in promoting uptake of the bacteria into these cells.

Biofilm Formations in Pediatric Respiratory Tract Infection : Part 1: Biofilm Structure, Role of Innate Immunity in Protection Against and Response to Biofilm, Methods of Biofilm Detection, Pediatric Respiratory Tract Diseases Associated with Mucosal Biofilm Formation

PURPOSE OF REVIEW

Biofilm represents an organized structure of microorganisms within an extracellular matrix attached to a surface. While the importance of biofilm in prosthetic heart valve and catheter-related infections has been known since the 1980s, the role of mucosal biofilm in human disease pathogenesis has only recently been elucidated. It is now clear that mucosal biofilm is present in both healthy and pathologic states. The purpose of this review is to examine the role of mucosal biofilm in pediatric respiratory infections.

RECENT FINDINGS

Mucosal biofilm has been implicated in relationship to several pediatric respiratory infections, including tonsillitis, adenoiditis, otitis media with effusion, chronic rhinosinusitis, persistent endobronchial infection, and bronchiectasis. In these conditions, core pathogens are detected in the biofilm, biofilm organisms are often detected by molecular techniques when conventional cultures are negative, and biofilm presence is more extensive in relation to disease than in healthy tissues. In chronic rhinosinusitis, the presence of polymicrobial biofilm is also a predictor of poorer outcome following sinus surgery. Biofilm in the tonsillar and adenoidal compartments plays a distinct role in contributing to disease in the middle ear and sinuses. Key observations regarding the relevance of biofilm to pediatric respiratory infections include (1) the association between the presence of biofilm and persistent/recurrent and more severe disease in these tissues despite antibiotic treatment, (2) linkage between biofilm core pathogens and acute infections, and (3) interrelationship between biofilm presence in one tissue and persistent or recurrent infection in an adjacent tissue. A greater understanding of the significance of mucosal biofilm will undoubtedly emerge with the development of effective means of eradicating mucosal biofilm.

Bacterial Ball as an Unusual Finding in Patients With Chronic Rhinosinusitis

OBJECTIVES

Pathophysiology of chronic rhinosinusitis (CRS) is very complex and has not yet been clearly understood. To date, various factors have been researched to have relations with the pathogenesis of CRS, such as superantigens and biofilms. Recently, we found an unusual pathological finding in patients with CRS, and we called this new entity as bacteria ball (or bioball). In this study, we analyze the clinical characteristics of bacteria ball occurred in CRS.

METHODS

This study enrolled consecutive 247 patients with CRS who underwent functional endoscopic sinus surgery from January 2015 to August 2016. The diagnosis of bacterial ball was made when negative in Gomori-methenamine-silver stain and positive in Gram stain. Histologically, bacterial ball was defined as acellular mucous materials with bacterial colonies and inflammatory cell infiltrates. We compared clinical data and computed tomography (CT) findings between fungal and bacterial balls.

RESULTS

Six cases (2.4%) of CRS were confirmed histologically as bacterial ball. Most of them were found in the maxillary sinus of CRS without nasal polyposis (66.7%). Bacterial ball was green or brown colored materials similar to fungal ball which was harder and tightly adherent to the antral mucosa. Compared to fungal ball, patients with bacterial ball showed significantly less peripheral eosinophils (P=0.011) and calcification in CT scans (P=0.003).

CONCLUSION

Bacterial ball is unusual findings occurred in patient with CRS which is different from fungal ball and biofilm. For diagnosis of bacterial ball, Gram stain is essentially required to identify bacterial colonies. Bacterial ball might appear to be evidence of a new strategy for living in the paranasal sinuses.

Biofilm and Osteitis in Refractory Chronic Rhinosinusitis

Our understanding of chronic rhinosinusitis (CRS) show biofilm and osteitis play a role in the disease's pathogenesis and refractory. Studies point to its role in pathogenesis and poor prognosis. Outside the research laboratory, biofilm detection remains difficult and specific treatment remains elusive. It is believed that osteitis is a nidus of inflammation and occurs more commonly in patients with refractory CRS. However, osteitis may be exacerbated by surgery and a marker of refractory disease, not a causative agent. Surgery remains the mainstay treatment for biofilm and osteitis with mechanical disruption and removal of disease load providing the most effective treatment.

Detection of Biofilms in Biopsies from Chronic Rhinosinusitis Patients: In Vitro Biofilm Forming Ability and Antimicrobial Susceptibility Testing in Biofilm Mode of Growth of Isolated Bacteria

Chronic rhinosinusitis (CRS) is the most common illness among chronic disorders that remains poorly understood from a pathogenic standpoint and has a significant impact on patient quality of life, as well as healthcare costs. Despite being widespread, little is known about the etiology of the CRS. Recent evidence, showing the presence of biofilms within the paranasal sinuses, suggests a role for biofilm in the pathogenesis. To elucidate the role of biofilm in the pathogenesis of CRS, we assessed the presence of biofilm at the infection site and the ability of the aerobic flora isolated from CRS patients to form biofilm in vitro. For selected bacterial strains the susceptibility profiles to antibiotics in biofilm condition was also evaluated.Staphylococci represented the majority of the isolates obtained from the infection site, with S. epidermidis being the most frequently isolated species. Other isolates were represented by Enterobacteriaceae or by species present in the oral flora. Confocal laser scanning microscopy (CLSM) of the mucosal biopsies taken from patients with CRS revealed the presence of biofilm in the majority of the samples. Strains isolated from the specific infection site of the CRS patients were able to form biofilm in vitro at moderate or high levels, when tested in optimized conditions. No biofilm was observed by CLSM in the biopsies from control patients, although the same biopsies were positive for staphylococci in microbiological culture analysis. Drug-susceptibility tests demonstrated that the susceptibility profile of planktonic bacteria differs from that of sessile bacteria in biofilms.

Biofilms in chronic rhinosinusitis: Pathophysiology and therapeutic strategies

BACKGROUND

There is increasing evidence that biofilms are critical to the pathophysiology of chronic infections including chronic rhinosinusitis (CRS). Until relatively recently, our understanding of biofilms was limited. Recent advances in methods for biofilm identification and molecular biology have offered new insights into the role of biofilms in CRS. With these insights, investigators have begun to investigate novel therapeutic strategies that may disrupt or eradicate biofilms in CRS.

OBJECTIVE

This review seeks to explore the evidence implicating biofilms in CRS, discuss potential anti-biofilm therapeutic strategies, and suggest future directions for research.

RESULTS

The existing evidence strongly supports the role of biofilms in the pathogenesis of CRS. Several anti-biofilm therapies have been investigated for use in CRS and these are at variable stages of development. Generally, these strategies: 1) neutralize biofilm microbes; 2) disperse existing biofilms; or 3) disrupt quorum sensing. Several of the most promising anti-biofilm therapeutic strategies are reviewed.

CONCLUSIONS

A better understanding of biofilm function and their contribution to the CRS disease process will be pivotal to the development of novel treatments that may augment and, potentially, redefine the CRS treatment paradigm. There is tremendous potential for future research.

A comprehensive review of the nasal microbiome in chronic rhinosinusitis (CRS)

Chronic rhinosinusitis (CRS) has been known as a disease with strong infectious and inflammatory components for decades. The recent advancement in methods identifying microbes has helped implicate the airway microbiome in inflammatory respiratory diseases such as asthma and COPD. Such studies support a role of resident microbes in both health and disease of host tissue, especially in the case of inflammatory mucosal diseases. Identifying interactive events between microbes and elements of the immune system can help us to uncover the pathogenic mechanisms underlying CRS. Here we provide a review of the findings on the complex upper respiratory microbiome in CRS in comparison with healthy controls. Furthermore, we have reviewed the defects and alterations of the host immune system that interact with microbes and could be associated with dysbiosis in CRS.

Enhanced expressions of lysozyme, SLPI and glycoprotein 340 in biofilm-associated chronic rhinosinusitis

Lysozyme, secretory leukocyte proteinase inhibitor (SLPI) and glycoprotein 340 (gp340) are important effectors of the innate immune system in sinonasal mucosa. Bacterial biofilms (BBF) are highly organized bacterial communities resistant to host defense systems. The aim of this study was to investigate the expression of lysozyme, SLPI and gp340 in sinus mucosa from chronic rhinosinusitis (CRS) patients with different BBF status. In this prospective cohort study, 63 CRS patients undergoing endoscopic sinus surgery and 20 controls were enrolled and their mucosal samples from ethmoid sinus were obtained. Biofilms were examined by confocal scanning laser microscopy (CSLM), and the expressions of lysozyme, SLPI and gp340 in mRNA and protein levels were detected using reverse transcription polymerase chain reaction (RT-PCR), immunohistochemistry and Western blot assay, respectively. As a result, 35/63 (55.6%) of the patients were BBF positive in the CRS group and none in controls. Both mRNA and protein levels of lysozyme, SLPI and gp340 in patients with CRS were significantly higher than those in controls. When sub-classified according to BBF status, the CRS patients with BBF revealed the significantly enhanced mRNA and protein levels of lysozyme, SLPI and gp340. In conclusion, our study demonstrates that lysozyme, SLPI and gp340 are constitutively expressed in sinus mucosa and their up-regulated expressions on both the mRNA and protein levels are associated with BBF in CRS patients. These findings may offer an insight into the interaction between BBF and the innate immune system.

Cousins, siblings, or copies: the genomics of recurrent Staphylococcus aureus infections in chronic rhinosinusitis

BACKGROUND

Staphylococcus aureus infection is known to play a role in recalcitrant chronic rhinosinusitis (CRS). However, it is unknown if recurrent S. aureus infections are caused by the same strain or are due to independent acquisitions of different strains.

METHODS

Samples were collected from patients with CRS from July 2011 to August 2012. S. aureus was isolated from mucosal swabs and tissue specimens from patients who underwent surgery during the study period, or from swabs of areas of purulence taken in the postoperative period under endoscopic guidance. Pulsed-field gel electrophoresis was used to characterize S. aureus isolates.

RESULTS

Thirty-four patients were included in the study; 79% showed persistence of the same S. aureus strain in their paranasal sinuses (p = 0.001; H1 ≠ 50%). Furthermore, a significantly high frequency of patients with known biofilm status were positive for S. aureus biofilm (p = 0.002; H1 ≠ 50%). When patients were stratified according to disease evolution postsurgery, certain strains appeared to be more commonly associated with symptom persistence.

CONCLUSION

The same S. aureus strain appears to persist in the paranasal sinuses of CRS patients despite multiple courses of culture-directed antibiotics. This suggests that conventional antimicrobial therapies in patients with CRS may not eliminate the organism. This may be partly explained by the formation of biofilms in the paranasal sinus region.

Hematoxylin and eosin staining for detecting biofilms: practical and cost-effective methods for predicting worse outcomes after endoscopic sinus surgery

Objectives

Although biofilms have been implicated in poor prognosis after endoscopic sinus surgery (ESS), traditional methods detecting biofilm such as scanning electron microscope and confocal scanning laser microscope were rarely used in the practice. The aims of this study was to determine whether the presence or absence of a biofilm detected by hematoxylin and eosin (H&E) staining followed by light microscopy (LM) that is widely used in daily practice, predicts surgical outcomes after ESS.

Methods

Retrospective analysis of prospectively collected data. Fifty-five consecutive adult patients (>18 years) who underwent ESS for chronic rhinosinusitis with a minimum of 12-months of follow-up were enrolled in this study. Random sinonasal mucosal samples were assessed for biofilm presence using H&E staining with LM. Three independent observers scored whether a biofilm was present or absent based on H&E staining/LM, and the interrater variability was calculated. Pre- and postoperative sinus symptoms and sinonasal mucosal grading were assessed.

Results

Biofilms were present in 28 patients (51%), and the intraclass correlation coefficient according to H&E staining/LM was 0.731. The presence of a biofilm was associated with a higher preoperative Lund-MacKay computed tomography score (22.3 for biofilm-positive patients vs. 18.6 for biofilm-negative patients; P=0.021) and persistent inflammation (mucosal edema and discharge) after ESS (P<0.05).

Conclusions

The presence or absence of a biofilm based on H&E staining/LM is correlated with disease severity and surgical outcomes after ESS. H&E staining/LM for detecting biofilm could be practical and cost-effective methods for predicting prognosis of ESS.

Bacterial biofilm formation after nasal packing in nasal mucosa-wounded mice

BACKGROUND

Bacterial biofilm plays an important role in recalcitrant chronic rhinosinusitis. Staphylococcus aureus is a crucial pathogen in chronic rhinosinusitis and S. aureus biofilm is related to unfavorable postoperative outcomes. Although S. aureus is known to be the most common bacteria leading to postoperative infection, whether biofilm forms on the wound surface after functional endoscopic sinus surgery and the relationship between biofilm formation and surgery are still not clear. This study was designed to observe whether S. aureus biofilm forms in mice with wounded nasal mucosa mice after bacteria inoculation.

METHODS

Three hundred twenty-four wild-type male C57BL/6 mice were recruited for the experiment. Except for the four used in the preliminary experiment, the mice were randomly divided into four groups: a wound plus packing group (group A), a wound group (group B), a packing group (group C), and a control group (group D). After treatment, groups A, B, and C were inoculated with S. aureus suspension at 1 × 10(9) CFU/mL in the right nasal cavity; sterile physiological saline was used instead of bacteria suspension for group D. Confocal laser scanning microscopy was used to detect the biofilm. A nasal lavage culture was also completed.

RESULTS

Biofilm formation was found in group A on the 3rd, 7th, and 15th days after inoculation with growth rates of 10, 25, and 40%, respectively. Three cases of biofilm were also detected in group B on the 15th day postinoculation. There was no biofilm observed on the nasal mucosa in group C or D. The nasal lavage culture showed that the inoculated bacteria stayed on the nasal mucosa temporarily after inoculation.

CONCLUSION

Our results indicate that a nasal wound, nasal packing, and the existence of pathogenic bacteria are all essential elements for biofilm formation in healthy mice. This result indicated that biofilm formation may be avoided by shortening the duration of nasal packing and reducing the nasal wound.

Host-microbial interactions in patients with chronic rhinosinusitis

There has been considerable investigation of host-microbial interactions in patients with chronic rhinosinusitis (CRS) in hopes of elucidating mechanisms of disease and better treatment. Most attention has been paid to bacterial infection and potential underlying defects in innate immunity. Bacterial biofilm is present in most patients with CRS undergoing surgical intervention, and its presence is associated with more severe disease and worse surgical outcomes. A role for viral or fungal infection in patients with CRS is less clear. There is no evidence for a primary defect in mucociliary clearance in most patients with CRS. Decreased levels of certain antimicrobial proteins, most notably lactoferrin, have been found in sinus secretions, whereas levels of other antimicrobial proteins have been found to be normal. No primary defects in Toll-like receptors have been found in patients with CRS, although a 50% reduced expression of Toll-like receptor 9 was reported in patients with recalcitrant nasal polyps. A polymorphism in a bitter taste receptor was recently associated with refractory CRS and persistent Pseudomonas aeruginosa infection. A downregulation of innate immunity by maladaptive T_H2 tissue inflammation has also been described in patients with recalcitrant nasal polyps, suggesting a link to persistent infection. To date, an effective means of restoring host-microbial balance and mitigating disease in patients with CRS remains elusive.

Correlation between bacterial biofilms and osteitis in patients with chronic rhinosinusitis

OBJECTIVES/HYPOTHESIS

Bacterial biofilms (BBF) and osteitis are potential contributors to the local inflammatory load in chronic rhinosinusitis (CRS). This study investigated the relationship between BBF and osteitis status in CRS patients.

STUDY DESIGN

Prospective cohort study.

METHODS

Eighty-four CRS patients undergoing endoscopic sinus surgery and 22 control patients were enrolled in this study. Mucosal and bony samples from ethmoid sinus were obtained for confocal scanning laser microscopy and microscopic examination. Biofilm volume (BV), biofilm score (BS), histopathologic bony grade, Global Osteitis Scoring Scale (GOSS) score, and Hounsfield unit (HU) value on computed tomography were recorded. Associations between these parameters describing BBF and osteitis were assessed.

RESULTS

The histopathologic bony grade 2 (0-3) versus 0 (0-3) (P < 0.001), GOSS score 4.5 (0-31) versus 0 (0-26) (P = 0.014) and HU value 431.5 (310-509) versus 354 (288-499) (P < 0.001) in patients with BBF were greater than those without BBF. The bony grade (r = 0.683, P < 0.001 and r = 0.664, P < 0.001), GOSS score (r = 0.314, P = 0.004 and r = 0.312, P = 0.004), and HU value (r = 0.539, P < 0.001 and r = 0.520, P < 0.001) were significantly increased with higher BV and BS.

CONCLUSION

A total of 84.8% of the bone underlying mucosa with BBF had some form of osteitis in ethmoid sinus, and approximately 46.4% of CRS patients were from a subgroup with both BBF and osteitis. The volume of BBF correlated well with severity of osteitis in CRS patients.

Identifying intracellular Staphylococcus aureus in chronic rhinosinusitis: a direct comparison of techniques

BACKGROUND

The emerging concept of intracellular pathogens such as Staphylococcus aureus playing a role in chronic rhinosinusitis (CRS) has led to the development of numerous imaging techniques for their identification. Traditional methods of bacterial culture are not effective at localizing bacteria to the surface or within tissue samples. The aim of this study was to develop and validate a novel imaging technique using confocal scanning laser microscopy (CSLM) coupled with a fluorescence in situ hybridization (FISH) probe and nucleic acid counterstain (propidium iodide [PI]) that allows for simultaneous analysis of S. aureus intracellular status and surface biofilm within whole mucosal samples.

METHODS

A prospective study was performed including 17 patients undergoing endoscopic sinus surgery for CRS. Tissue samples were analyzed with both CSLM-FISH/PI and immunohistochemistry (IHC) for intracellular S. aureus status.

RESULTS

Using CSLM-FISH/PI intracellular S. aureus was identified in 9/17 (47%) patients and in 7/17 (39%) using IHC. Surface biofilm can be identified with CSLM-FISH/PI in the same piece of tissue; however, deeper imaging to the submucosa is impossible. IHC showed submucosal bacteria in three patients.

CONCLUSION

Both CSLM-FISH/PI and IHC are complementary techniques that can be used to identify intracellular S. aureus. CSLM-FISH/PI allows for the simultaneous detection of intracellular status and surface biofilm within the tissue analyzed. IHC has a role in the identification of intracellular and submucosal S. aureus within these tissues. Additional investigation is required to identify the true pathogenic nature of intracellular organisms as well as any relationship to surface biofilm status.

The influence of bacterial biofilm on the clinical outcome of chronic rhinosinusitis: a prospective, double-blind, scanning electron microscopy study

The aim of this study was to assess the influence of bacterial biofilms in chronic rhinosinusitis (CRS) patients on the clinical outcomes following endoscopic sinus surgery (ESS). This was a prospective, double-blind study. Patients undergoing ESS, because of CRS, were recruited. Overall 80 patients were qualified. For each of these demographic, clinical and radiologic characteristics were recorded. During surgery each patient had at least 7 mucosal specimens taken to assess, using scanning electron microscopy, the possible presence of bacterial biofilms. Prior to mucosa specimen excision, swabs for bacteriological and fungal analyses were taken. Each patient underwent perioperative and follow-up assessment at 3 and 6 months post-ESS. Biofilms were found in 33 (41.3%) patients (study group). From among the 47 patients without the presence of biofilms, 33 (control group) were taken to match the study group in age, gender and clinical characteristics. The intensity of subjective and objective CRS symptoms, as well as patient quality-of-life, did not correlate with the Lund and Mackay score (p > 0.05). Analysis of variance showed that, in the control group or the group as a whole, the intensity of subjective and objective symptoms decreased (p < 0.05), and the quality-of-life increased with time (p < 0.05). In conclusion, biofilm-positive patients tend to have a greater severity of disease preoperatively and continue to have persistent and more severe symptoms post-ESS. This study supports the role of biofilms in maintaining the chronic and recalcitrant nature of CRS. The lack of planktonic bacteria in post-operative sinus swabs does not rule out the presence of bacterial biofilms.

The microbiome of chronic rhinosinusitis: culture, molecular diagnostics and biofilm detection

Background

Bacteria and fungi are believed to influence mucosal inflammation in chronic rhinosinusitis (CRS). However their presence and relationship to disease is debated. This study used multiple detection methods to compare microbial diversity and microbial abundance in healthy and diseased sinonasal mucosa. The utility of contemporary detection methods is also examined.

Methods

Sinonasal mucosa was analyzed from 38 CRS and 6 controls. Bacterial and fungal analysis was performed using conventional culture, molecular diagnostics (polymerase chain reaction coupled with electrospray ionization time-of-flight mass spectrometry) and fluorescence in situ hybridization.

Results

Microbes were detected in all samples, including controls, and were often polymicrobial. 33 different bacterial species were detected in CRS, 5 in control patients, with frequent recovery of anaerobes. Staphylococcus aureus and Propionibacterium acnes were the most common organisms in CRS and controls, respectively. Using a model organism, FISH had a sensitivity of 78%, and a specificity of 93%. Many species were detected in both CRS and controls however, microbial abundance was associated with disease manifestation.

Conclusions

This study highlights some cornerstones of microbial variations in healthy and diseased paranasal sinuses. Whilst the healthy sinus is clearly not sterile, it appears prevalence and abundance of organisms is critical in determining disease. Evidence from high-sensitivity techniques, limits the role of fungi in CRS to a small group of patients. Comparison with molecular analysis suggests that the detection threshold of FISH and culture is related to organism abundance and, furthermore, culture tends to select for rapidly growing organisms.

Role of bacterial and fungal biofilms in chronic rhinosinusitis

Chronic rhinosinusitis (CRS) is a very common condition that remains poorly understood from a pathogenic standpoint. Recent interest has been sparked by a potential role for biofilms in this process, with a significant body of evidence implicating them in inciting sinonasal inflammation. Biofilms are clearly present on the sinus mucosa of CRS patients, and their presence there is associated with severe disease characteristics and surgical recalcitrance. We are beginning to understand the importance of the species within these biofilms, but there may be other as-yet-unidentified factors at play in influencing disease outcomes. Recent exciting research has emerged documenting the immune response to the presence of biofilms-research that will ultimately solidify the nature and extent of the contribution of biofilms in CRS pathogenesis. Future research should focus on evidence-based antibiofilm treatments with reference to efficacy and timing of treatment.

Noninvasive Staphylococcus aureus biofilm determination in chronic rhinosinusitis by detecting the exopolysaccharide matrix component poly-N-acetylglucosamine

BACKGROUND

The role that bacterial biofilms might play in recalcitrant forms of chronic rhinosinusitis (CRS) is increasingly being recognized. However, the detection of bacteria existing in this form, using standard culture, is limited by their unique metabolically inactive properties. All current biofilm diagnostic modalities require invasive mucosal biopsies, which limit their use to the operating theatre.

METHODS

Twenty CRS patients and 5 controls were enrolled in a prospective study to assess the feasibility of noninvasively diagnosing S. aureus biofilms by detecting the biofilm matrix polysaccharide poly-N-acetylglucosamine (PNAG). An immunofluorescence protocol was developed for PNAG detection and compared with both standard microbiological cultures and fluorescence in situ hybridization (FISH).

RESULTS

Thirteen of 20 CRS patients had evidence of S. aureus biofilm formation using FISH. Of these, 12 had detectable PNAG. Interestingly none of the S. aureus FISH-negative patients were PNAG-positive despite the presence of coagulase-negative Staphylococci biofilms, some of which may exhibit PNAG in their pathogenic forms. The development of a noninvasive S. aureus biofilm diagnostic test provides a reliable means to identify a high-risk group of CRS patients who harbor S. aureus biofilms. The ability to be used outside of the perioperative period to assess surgical efficacy, guide management, and evaluate new treatment modalities provides a significant advance in this field of research and clinical practice.

CONCLUSION

This study has confirmed the feasibility of noninvasive detection of S. aureus biofilms with a simple test that produces results comparable to the more invasive methods that are currently relied upon.

Bacterial biofilms in chronic rhinosinusitis and their relationship with inflammation severity

AIMS

To identify the presence of bacterial biofilms on mucosal specimens from chronic rhinosinusitis (CRS) patients, and evaluate their relationship with severity of CRS.

METHODS

A prospective study of biofilms presence on 24 CRS patients compared with 12 controls was designed. The presence of biofilms was determined by scanning electron microscopy (SEM), and associations with the preoperative Lund-MacKay CT scores, Johansson endoscopic scores, and the history of ESS were assessed.

RESULTS

Biofilms were found in 13/24 CRS patients (54.2%) but in only 1/12 controls (8.3%; P<0.01). CRS patients with and without biofilms had similar preoperative Lund-MacKay CT and Johansson endoscopic scores (P>0.05). Patients with revision ESS showed a tendency of higher biofilms incidence (5/7, 71.4%) than those undergoing their first procedure (8/17, 47.1%), but did not reach a significant difference (P>0.05).

CONCLUSIONS

The higher incidence of biofilms in CRS patients suggests a role in the pathogenesis of CRS, but no correlation with severity of CRS.

The multiplicity of Staphylococcus aureus in chronic rhinosinusitis: correlating surface biofilm and intracellular residence

OBJECTIVES/HYPOTHESIS

The biofilm paradigm of chronic rhinosinusitis (CRS) is increasingly understood to play a key role in the pathophysiology of this disease. The role of intracellular infection of sinonasal epithelial cells has been suggested as a potential reservoir of pathogenic organisms that can lead to recalcitrant disease despite maximal medical and surgical treatment. Could a surface biofilm play a role in allowing intracellular infection to occur, and what are the factors associated with potential intracellular infections? The aim of this study was to investigate these questions.

STUDY DESIGN

A prospective study including 36 CRS patients undergoing endoscopic sinus surgery and five control patients undergoing endonasal pituitary surgery.

METHODS

Sinonasal mucosa harvested at the time of surgery was examined with a Staphylococcus aureus fluorescence in situ hybridization probe and propodium iodide counterstain using the confocal scanning laser microscope for both biofilm status and evidence of intracellular organisms.

RESULTS

Intracellular S aureus was identified in 20/36 (56%) CRS patients compared to 0/8 (0%) control patients. CRS patients with intracellular infection were significantly more likely to harbor surface biofilm (20/20, P = .0014) and have a S aureus-positive culture swab (12/20, P = .0485).

CONCLUSIONS

This study gives further evidence supporting a role of intracellular S aureus in CRS. In all cases intracellular infection was associated with surface biofilm, suggesting a potential relationship between the two. Further work is required to delineate the true mechanisms of intracellular persistence and also the role that it plays in the recalcitrant nature of CRS.

Characterization of bacterial community diversity in chronic rhinosinusitis infections using novel culture-independent techniques

BACKGROUND

Chronic rhinosinusitis (CRS) with or without polyps is a common chronic upper airway condition of multifactorial origin. Fundamental to effective treatment of any infection is the ability to accurately characterize the underlying cause. Many studies have shown that only a small fraction of the total range of bacterial species present in CRS is detected through conventional culture-dependent techniques. Consequently, culture data are often unrepresentative of the true diversity of the microbial community within the sample. These drawbacks, along with the length of time required to complete the analysis, strongly support the development of alternative means of assessing which bacterial species are present. As such, molecular microbiological approaches that assess the content of clinical samples in a culture-independent manner could significantly enhance the range and quality of data obtained routinely from such samples. We aimed to characterize the bacterial diversity present in tissue and mucus samples taken from the CRS setting using molecular nonculture-dependent techniques.

METHODS

Through 16S ribosomal RNA (rRNA) gene clone sequencing and terminal restriction fragment length polymorphism (T-RFLP) analysis, the bacteria present in 70 clinical samples from 43 CRS patients undergoing endoscopic sinus surgery were characterized.

RESULTS

Bacterial T-RFLP profiles were generated for 70 of 73 samples and a total of 48 separate bands were detected. Species belonging to 34 genera were identified as present by clone sequence analysis. Of the species detected, those within the genera Pseudomonas, Citrobacter, Haemophilus, Propionibacterium, Staphylococcus, and Streptococcus were found numerically dominant, with Pseudomonas aeruginosa the most frequently detected species.

CONCLUSION

This study has validated the use of the culture-independent technique T-RFLP in sinonasal samples. Preliminary characterization of the microbial diversity in CRS suggests a complex range of common and novel bacterial species within the upper airway in CRS, providing further evidence for the polymicrobial etiology of CRS.

Adaptive immune responses in Staphylococcus aureus biofilm-associated chronic rhinosinusitis

BACKGROUND

The etiopathogenesis of chronic rhinosinusitis (CRS) is currently an area of intense debate. Recently, biofilms have been proposed as a potential environmental trigger in this disease. In particular, Staphylococcus aureus biofilms appear to be a predictor of severe disease recalcitrant to current treatment paradigms. However, direct causal links between biofilms and host immune activation are currently lacking. This study aimed to document both the adaptive immune responses that characterize S. aureus biofilm-associated CRS and the relative contributions of staphylococcal superantigens and S. aureus biofilms in the inflammatory make-up of this disease.

METHODS

A total of 53 disease subjects and 15 controls were recruited. Sinonasal mucosa was collected for the determination of S. aureus and Haemophilus influenzae biofilms and presence of total and superantigen-specific IgE and for the measurement of cytokines that characterize the T-helper pathways.

RESULTS

Staphylococcus aureus biofilms and superantigens are significantly associated in CRS patients, suggesting the biofilm may be a nidus for superantigen-eluting bacteria. The presence of S. aureus biofilms is associated with eosinophilic inflammation, across the spectrum of CRS, on the back of a T-helper(2) skewing of the host's adaptive immune response (elevated Eosinophilic Cationic Protein and IL-5). This can be distinguished from the superantigenic effect resulting in the induction of IgE.

CONCLUSION

This study provides novel evidence of a link between S. aureus biofilms and skewing of the T-cell response toward the T-helper(2) pathway that is independent of superantigen activities. Further research is required to confirm the cause-effect relationship of this association.

Evaluation of bacterial adherence and biofilm arrangements as new targets in treatment of chronic rhinosinusitis

Several promising candidate drugs that target bacterial adherence and biofilm formation are being developed. Such hopeful drugs cannot be studied in chronic rhinosinusitis (CRS) without the evaluation of such virulence criteria in different forms of the disease with and without nasal polyposis (CRSwNP and CRSsNP). The aim of this study was to evaluate bacterial adherence, response to antibiotics and degree of accumulation of bacterial biofilms as new targets of treatment in CRSwNP and CRSsNP. Twenty CRS patients and 10 normal subjects with airway obstructing concha bullosa were prospectively enrolled in the present study. Scanning electron microscopy and cultures were performed on paranasal sinus tissue samples. Bacterial adherence tests using the tissue culture plate method were measured quantitatively. Strongly adherent bacteria were identified significantly in 6/9 (77%) cases of CRSsNP in comparison to 1/7 (14%) cases of CRSwNP. Strongly adherent bacteria that were sensitive to ciprofloxacin, vancomycin, and impenim were identified in 75% of the cultured coagulase positive staphylococci. A significant difference (P = 0.007) in the degree of accumulation of bacterial biofilms existed between the two groups. In CRSsNP, a more advanced stage of bacterial biofilms with strong bacterial adherence was observed which make them attractive targets for new drugs. In CRSwNP, lower stage bacterial biofilms with low bacterial adhesion were identified, which may help explain the low bacterial virulence in an environment of suboptimal, organizational arrangements.

Relationship between bacterial biofilm and clinical features of patients with chronic rhinosinusitis

The purpose of this study was to investigate the incidence of bacterial biofilm (BBF) in patients with chronic rhinosinusitis (CRS) using confocal scanning laser microscopy (CSLM), and to assess the relationship between BBF and clinical features of CRS. This was a prospective observational study of the sinus mucosa of 27 CRS patients and 10 controls undergoing endoscopic sinus surgery (ESS). Clinical information was recorded preoperatively and sinus mucosal specimens were collected intraoperatively. We determined the existence of BBF with BacLight/CSLM detection, and proposed a BBF scoring system based on its morphologic features. Clinical parameters, including symptom score, endoscopy score, CT score and symptom duration, were compared between CRS patients with and without BBF, and among CRS patients with different BBF score. BBF was found in 16/27 (59.26%) CRS patients and none in 10 controls. SNOT-20 symptom score and individual symptoms including need to blow nose, cough and postnasal discharge were significantly more severe in CRS patients with BBF than those without. BBF score was better correlated than BBF existence with SNOT-20 score (r = 0.811, P < 0.001 vs. r = 0.604, P = 0.001), and correlated with both endoscopy score (r = 0.490, P = 0.009) and symptom duration (r = 0.487, P = 0.010), neither was correlated with BBF (P = 0.824; P = 0.263). BBF score is likely to guide anti-BBF therapy in CRS patients.

Do biofilms contribute to the initiation and recalcitrance of chronic rhinosinusitis?

Chronic rhinosinusitis is a common disease whose underlying aetiopathogenesis has not been completely understood. Amongst a range of other potential environmental triggers in this disease, a role has recently been proposed for bacterial biofilms. Adopting the biofilm paradigm to explain the initiation and maintenance of this disease may help to clarify previous inconsistencies in this disease that have resulted in the role of bacteria being questioned. Of particular interest is the association of bacterial biofilms with recalcitrant disease states. Over the last five years, research has progressed rapidly since biofilms were first identified on the surface of diseased sinonasal mucosa. Their presence there has now been associated with more severe disease that is often recalcitrant to current management paradigms. Technological advances are allowing accurate characterization of the bacterial and fungal species within these biofilms, which would appear to be an important step in improving our understanding of how these bacterial communities might interact with the host to cause disease. This is an unanswered, yet highly important, question in this field of research that will undoubtedly be an area of investigation in the near future. As the body of evidence suggesting biofilms may be involved in this disease grows, research interest has switched to the development of antibiofilm therapies. Given the unique properties of bacteria existing in this form, biofilm eradication strategies will need to incorporate novel medical therapies into established surgical practices as we attempt to improve the outcomes of our most difficult patients.

Are biofilms associated with an inflammatory response in chronic rhinosinusitis?

BACKGROUND

Bacterial biofilms have been identified on the sinonasal mucosa of patients with chronic rhinosinusitis (CRS) but also on control samples. Their role in the disease pathogenesis is unproven. The objective of this study was to further evaluate the role of biofilms in CRS by assessing whether they are associated with an inflammatory response.

METHODS

Mucosal samples were collected from 18 patients with CRS and 7 normal subjects. Bacteria on the mucosal surface were identified by Gram stain. Immune cells were identified by Giemsa stain and immunohistochemistry (IHC). The number of local immune cells was recorded beneath areas of the mucosal surface both colonized with and free from bacteria.

RESULTS

In CRS patients, biofilms that were directly opposed to a disrupted epithelial layer were associated with more T lymphocytes (p = 0.01), and more macrophages (p = 0.003) than areas of mucosa without bacteria present. Biofilms associated with but not directly opposed to the epithelium were not associated with raised numbers of immune cells.

CONCLUSION

Not all surface bacterial colonies are associated with a particular inflammatory response in CRS. Biofilms adherent to a disrupted epithelial layer are associated with higher numbers of immune cells and therefore appear to have a role in the pathogenesis of CRS.

What is the origin of Staphylococcus aureus in the early postoperative sinonasal cavity?

BACKGROUND

Despite increasing evidence of a role for Staphylococcus aureus (S. aureus) biofilms in chronic rhinosinusitis (CRS), the origin of this organism in the postsurgical sinonasal cavity had been unclear. Recently, we suggested that the increased culture rate of S. aureus following endoscopic sinus surgery (ESS) may be related to biofilm activity. This study, therefore, was designed to evaluate the origin of early postoperative sinonasal S. aureus and assess the early postoperative outcomes in patients culture-positive for this organism.

METHODS

Twenty-nine patients undergoing ESS for medically-recalcitrant CRS were prospectively enrolled. A comprehensive intraoperative S. aureus screening protocol was followed for all patients (including swabs for culture and tissue for fluorescence in situ hybridization [FISH] S. aureus biofilm analysis); early postoperative management included endoscopically-guided swabs for culture in all patients.

RESULTS

Twenty of 29 (69.0%) patients cultured S. aureus postoperatively, of which 17 of 20 (85.0%) were screen-positive at surgery. Seven of 11 (63.6%) intraoperatively biofilm-positive but culture-negative patients progressed to culture S. aureus post-ESS. S. aureus culture was associated with selected poorer early post-ESS outcomes.

CONCLUSION

S. aureus persists in the sinonasal cavity despite ESS. The postoperative culture of sinonasal S. aureus in patients previously biofilm-positive but culture-negative may reflect the dynamic ability of S. aureus to adapt to the surgically-altered microenvironment with subsequent biofilm dispersal and release of planktonic clones.

Biofilms in chronic rhinosinusitis with nasal polyps

OBJECTIVE

(1) Evaluate the presence of biofilms in patients with chronic sinusitis with nasal polyps (CRSwNP) and (2) investigate the association of biofilm presence and CRSwNP.

STUDY DESIGN

Cross-sectional study.

SETTING

University-based tertiary care center.

SUBJECTS AND METHODS

The study group consisted of 33 consecutive patients undergoing functional endoscopic sinus surgery for CRSwNP. The control group consisted of 27 control patients undergoing septoplasty for nasal obstruction without diagnosis of chronic sinusitis. Mucosal samples were harvested intraoperatively for scanning electron microscopic examination to determine biofilm presence. Statistical analysis was performed. For all statistical tests, P = .05 was considered significant.

RESULTS

Biofilms were found in 24 (72.7%) of the 33 patients with CRSwNP and in 13 (48.1%) of the 27 septoplasty patients (odds ratio = 2.87; 95% confidence interval, 0.98-8.42; P = .051).

CONCLUSION

(1) Biofilms were present in patients undergoing functional endoscopic sinus surgery for CRSwNP and also in controls without chronic sinusitis. This suggests that biofilms may not be sufficient to cause chronic sinusitis without other cofactors. Host factors could be the responsible for the pathogenesis of biofilms. (2) Although the prevalence of biofilms in patients with CRSwNP was not significantly different from that in the controls, the extremely wide 95% confidence interval, which is just below unity, suggests that a meaningful clinical difference may have been missed because of low statistical power. Further studies are necessary.

Canadian clinical practice guidelines for acute and chronic rhinosinusitis

This document provides healthcare practitioners with information regarding the management of acute rhinosinusitis (ARS) and chronic rhinosinusitis (CRS) to enable them to better meet the needs of this patient population. These guidelines describe controversies in the management of acute bacterial rhinosinusitis (ABRS) and include recommendations that take into account changes in the bacteriologic landscape. Recent guidelines in ABRS have been released by American and European groups as recently as 2007, but these are either limited in their coverage of the subject of CRS, do not follow an evidence-based strategy, or omit relevant stakeholders in guidelines development, and do not address the particulars of the Canadian healthcare environment.

Advances in understanding the pathophysiology of CRS, along with the development of appropriate therapeutic strategies, have improved outcomes for patients with CRS. CRS now affects large numbers of patients globally and primary care practitioners are confronted by this disease on a daily basis. Although initially considered a chronic bacterial infection, CRS is now recognized as having multiple distinct components (eg, infection, inflammation), which have led to changes in therapeutic approaches (eg, increased use of corticosteroids). The role of bacteria in the persistence of chronic infections, and the roles of surgical and medical management are evolving. Although evidence is limited, guidance for managing patients with CRS would help practitioners less experienced in this area offer rational care. It is no longer reasonable to manage CRS as a prolonged version of ARS, but rather, specific therapeutic strategies adapted to pathogenesis must be developed and diffused.

Guidelines must take into account all available evidence and incorporate these in an unbiased fashion into management recommendations based on the quality of evidence, therapeutic benefit, and risks incurred. This document is focused on readability rather than completeness, yet covers relevant information, offers summaries of areas where considerable evidence exists, and provides recommendations with an assessment of strength of the evidence base and degree of endorsement by the multidisciplinary expert group preparing the document.

These guidelines have been copublished in both Allergy, Asthma & Clinical Immunology and the Journal of Otolaryngology-Head and Neck Surgery.

Different biofilms, different disease? A clinical outcomes study

OBJECTIVES/HYPOTHESIS

A potential role for biofilms in Chronic Rhinosinusitis (CRS) has been proposed, and the adverse impact they have on disease severity and postoperative outcomes has also been well described. Recent advances have allowed the species within the biofilms of CRS patients to be clearly characterized. This study investigates whether different biofilm species have different disease outcomes.

STUDY DESIGN

Retrospective review.

METHODS

Twenty-four patients with medically recalcitrant CRS undergoing Endoscopic Sinus Surgery (ESS), in whom we had previously characterized their biofilms using fluorescence in situ hybridization (FISH), were reviewed a median of 11 months after their surgery. They were evaluated for preoperative disease markers and evidence of on-going disease in the postoperative period.

RESULTS

Thirty-seven biofilms were identified in the 24 patients. Almost half had polymicrobial biofilms. The presence of polymicrobial, rather than single-species biofilms adversely affected preoperative disease severity but did not alter postsurgical outcome. Patients with single organism Haemophilus influenzae biofilms presented with mild disease symptomatically and radiologically and achieved normal mucosa a short time after their surgery. Conversely, patients with Staphlococcus aureus in their biofilm makeup had more severe disease and a more complicated postoperative course. The effect of Pseudomonas aeruginosa and fungal biofilms is less clear.

CONCLUSIONS

Different biofilm species are associated with different disease phenotypes. H. influenzae biofilms are typically found in patients with mild disease, whereas S. aureus is associated with a more severe, surgically recalcitrant pattern.