Impaired mucosal healing and infection associated with Staphylococcus aureus after endoscopic sinus surgery

Sinus Irrigation with N-Acetylcysteine after Endoscopic Sinus Surgery for Chronic Rhinosinusitis: A Preliminary Report of a Single-Blind Randomized Controlled Trial

Nasal irrigation is crucial following endoscopic sinus surgery (ESS), especially for managing chronic rhinosinusitis (CRS). This study assessed the effectiveness of N-acetylcysteine (NAC) irrigation during the post-ESS period of patients with CRS without nasal polyposis. In this prospective, single-blind randomized controlled trial, 49 patients (NAC, n = 24; saline, n = 25) undergoing ESS were assigned to receive either NAC or saline irrigations twice daily for a month. The preoperative and postoperative assessments conducted included Lund-Macka (LM) and Lund-Kennedy (LK) endoscopic scores, the Nasal Obstruction Symptom Evaluation (NOSE) scale, and the Sino-Nasal Outcome Test-20 (SNOT-20). At 2 weeks, 1 month, and 3 months after the operation, endoscopic findings and symptoms were evaluated. Both groups showed no differences in age, sex, LM and LK scores, NOSE scale, and SNOT-20 preoperatively. In terms of the endoscopic findings regarding the sinonasal mucosa after ESS, the NAC group had slightly lower scores 2 weeks, 1 month, and 3 months after the operation, but this difference was not statistically significant. The NAC group showed significant improvement in VAS scores, namely, postnasal drip (1.0, p = 0.041), smell dysfunction (0.8, p = 0.003), and crust (1.5, p = 0.034), compared to the control group's scores of 2.6, 4.7, and 3.6, respectively, 2 weeks after the operation, although no significant differences were observed in VAS scores for any symptoms 1 and 3 months after the operation. NAC was well tolerated, and no adverse events were reported. NAC irrigation showed benefits over saline irrigation in terms of improving postnasal drip, smell dysfunction, and crust after ESS for CRS without nasal polyposis in the immediate postoperative period.

The Effect of Corticosteroids on Sinus Microbiota in Chronic Rhinosinusitis Patients with Nasal Polyposis

BACKGROUND

Chronic rhinosinusitis with nasal polyposis (CRSwNP) is a multifactorial disease with no known single cause, but it is thought that bacteria play a role in the disease process.

OBJECTIVE

This pilot study aims to assess the longitudinal effect of corticosteroid therapy on sinus microbiota in chronic rhinosinusitis patients with nasal polyposis (CRSwNP).

METHODS

A longitudinal prospective case-control study was done on patients with CRSwNP and healthy controls. Patients with CRSwNP were randomly allocated to a corticosteroids and antibiotics treatment group (CRSwNP-SA) or a corticosteroid-only treatment group (CRSwNP-S). Data were collected at three-time points (before treatment, 1, and 3 months after treatment). Specimens were cultured and matrix-assisted laser desorption ionization-time of flight (MALDI-TOF) mass spectrometry (MS) was used as a bacterial detection method.

RESULTS

Data from 29 patients with CRSwNP (16 CRSwNP-SA and 13 CRSwNP-S) was compared to 15 healthy subjects. Patients reported significant symptom improvement initially (1 month), but not in the long-term (3 months). This result was found in both treatment groups, whether or not antibiotics were used. After 3 months from treatment, the prevalence of Corynebacterium genera tended to increase in the CRSwNP-SA, while Staphylococcus and Gram-negative genera (Pseudomonas) tended to increase in the CRSwNP-S. Smoking, aspirin sensitivity, and previous endoscopic sinus surgery were found to be co-factors significantly associated with the response to systemic corticosteroid therapy.

CONCLUSION

In this pilot study, both treatment options were effective to improve symptoms in the short-term but not in the long-term, and were not linked to any clear sinus microbiota response. As a result, this study supports the avoidance of systemic antibiotics without evidence of active infection.

Wound healing in endoscopic sinus surgery: Phase 1 clinical trial evaluating the role of Chitogel with adjuvants

OBJECTIVES

This study aimed to determine the safety and efficacy of Chitogel, with and without Deferiprone (Def) and Gallium Protoporphyrin (GaPP), as a promoter of wound healing to improve surgical outcomes after endoscopic sinus susgery.

DESIGN

A double-blinded, randomised control human clinical trial was conducted in patients undergoing ESS as a treatment for chronic rhinosinusitis. Participants underwent functional ESS or FESS with drill out as required and were randomised to receive test product Chitogel, Chitogel in combination with Def or Def-GaPP versus no packing (control).

SETTING

Ostial stenosis and persistent inflammation are the main reasons for revision endoscopic sinus surgery (ESS). Post-operative (PO) dressings can improve PO wound healing and patient outcomes after ESS.

PARTICIPANTS

Eighty two patients were included in this study with 79 patients completing the study with 40 undergoing full house FESS and 39 FESS plus frontal drillout.

MAIN OUTCOME MEASURES

Patients were followed up at 2, 6 and 12 weeks PO, and outcome scores such as SNOT-22, VAS and LKS, pre and post-surgery (12 weeks) were compared.

RESULTS

Seventy nine patients completed the study, there was a significant reduction in SNOT-22 score and improvement of VAS at 12 weeks in patients treated with Chitogel compared to control (p < .05). In those patients, the mean ostium area for the Chitogel and the Chitogel + Def + GaPP groups was higher across all three sinuses compared to the no-treatment control group, without statistical significance. Sphenoid sinus ostium was significantly more patent in patients treated with Chitogel compared to the control at the 12-week time point (p < .05).

CONCLUSION

Chitogel as a PO dressing after ESS results in the best patient-reported symptom scores and objective measurements. The combination of Def and GaPP to Chitogel though proving safe, had no effect on the ostium patency or mucosal healing.

Sinonasal Outcomes Using Oral Corticosteroids in Patients with Chronic Rhinosinusitis with Nasal Polyps and Positive Sinonasal Cultures

Introduction Patients with chronic rhinosinusitis with nasal polyps (CRSwNP) and positive sinonasal bacterial cultures may be recalcitrant to topical therapy alone due to the additional local inflammatory burden associated with bacterial infection/colonization.

Objective To evaluate sinonasal outcomes in CRSwNP patients with a positive perioperative bacterial culture, who were treated with postoperative intranasal corticosteroids (INCS) alone versus INCS in combination with a short-term course of oral corticosteroids (OCS).

Methods This is a retrospective chart review of CRSwNP patients. A total of 59 patients met inclusion criteria, including positive perioperative bacterial culture and treatment with INCS with or without concomitant use of OCS. Two cohorts were formed based on the chosen postoperative medical treatment; 32 patients underwent postoperative INCS alone, while 27 underwent INCS plus a ≤ 2-week course of OCS. The 22-item sinonasal outcome test (SNOT-22) scores and Lund-Kennedy scores (LKS) were assessed preoperatively, and at 2-week, 4-week, and 4 to 6 months after endoscopic sinus surgery (ESS).

Results There were no statistically significant differences in postoperative sinonasal symptoms or endoscopic scores between the cohorts treated with INCS plus OCS versus those prescribed INCS alone (p > 0.05). Our regression model failed to demonstrate a relationship between the use of OCS and better sinonasal outcomes at 2-week, 4-week, and 4 to 6 months after ESS (p > 0.05).

Conclusion Our study suggests that in a cohort of CRSwNP patients with recent bacterial infections, the postoperative use of combined OCS and INCS did not result in a statistical improvement of endoscopic and symptomatic outcomes over INCS irrigation alone. However, both treatment groups had a clinically significant improvement based on the Minimal Clinically Important Difference.

May Staphylococcus lugdunensis Be an Etiological Factor of Chronic Maxillary Sinuses Infection?

Staphylococcus lugdunensis is an opportunistic pathogen found in the healthy human skin microbiome bacterial community that is able to cause infections of diverse localization, manifestation, and course, including laryngological infections, such as necrotizing sinusitis. Chronic maxillary sinusitis is a disease present in up to one third of European and American populations, and its etiology is not fully described. Within this study, we aimed to characterize 18 S. lugdunensis strains recovered from maxillary sinuses and evaluate them as etiological agents of chronic disease. We performed MLST analysis, the complex analysis of both phenotypic and genetic virulence factors, antibiotic susceptibility profiles, and biofilm formation assay for the detection of biofilm-associated genes. Altogether, S. lugdunensis strains were clustered into eight different STs, and we demonstrated several virulence factors associated with the chronic disease. All tested strains were able to produce biofilm in vitro with numerous strains with a very strong ability, and overall, they were mostly susceptible to antibiotics, although we found resistance to fosfomycin, erythromycin, and clindamycin in several strains. We believe that further in-depth analysis of S. lugdunensis strains from different niches, including the nasal one, should be performed in the future in order to reduce infection rate and broaden the knowledge about this opportunistic pathogen that is gaining attention.

Is there a role for antibiotics in the treatment of chronic rhinosinusitis?

Rhinosinusitis is one of the most common reasons for adult outpatient antibiotic prescriptions, though there is little clinical evidence to support this practice, especially for chronic rhinosinusitis. Despite considerable research, the etiology of chronic rhinosinusitis, including the pathogenic role of microbes, remains poorly understood. Rigorous studies of the efficacy of antibiotic treatment of chronic sinusitis are surprisingly few in number and the results are somewhat conflicting. This review article will review the rationales for and against the treatment of chronic rhinosinusitis with antibiotics, based on current evidence and understanding of pathophysiology, and will also summarize the current guidelines.

Characterising clinical Staphylococcus aureus isolates from the sinuses of patients with chronic rhinosinusitis

The role of Staphylococcus aureus in the pathogenesis of the chronic sinonasal disease chronic rhinosinusitis (CRS), has not been definitively established. Comparative analyses of S. aureus isolates from CRS with those from control participants may offer insight into a possible pathogenic link between this organism and CRS. The intra- and inter-subject S. aureus strain-level diversity in the sinuses of patients with and without CRS were compared in this cross-sectional study. In total, 100 patients (CRS = 64, control = 36) were screened for S. aureus carriage. The overall carriage prevalence of S. aureus in this cohort was 24% (CRS n = 13, control n = 11). Cultured S. aureus isolates from 18 participants were strain-typed using spa gene sequencing. The bacterial community composition of the middle meatus was assessed using amplicon sequencing targeting the V3V4 hypervariable region of the bacterial 16S rRNA gene. S. aureus isolates cultured from patients were grown in co-culture with the commensal bacterium Dolosigranulum pigrum and characterised. All participants harboured a single S. aureus strain and no trend in disease-specific strain-level diversity was observed. Bacterial community analyses revealed a significant negative correlation in the relative abundances of S. aureus and D. pigrum sequences, suggesting an antagonistic interaction between these organisms. Co-cultivation experiments with these bacteria, however, did not confirm this interaction in vitro. We saw no significant associations of CRS disease with S. aureus strain types. The functional role that S. aureus occupies in CRS likely depends on other factors such as variations in gene expression and interactions with other members of the sinus bacterial community.

Postoperative antibiotic use in patients with unilateral purulent chronic rhinosinusitis

OBJECTIVES

To describe our experience with the use of postoperative antibiotics in the management of unilateral chronic rhinosinusitis (CRS) patients with active infection at the time of surgery, and to evaluate the need for routine postoperative antibiotic administration in this population.

METHODS

This retrospective chart review analyzed the medical records of all patients who underwent endoscopic sinus surgery for unilateral purulent CRS between November 2013 and September 2019 at a tertiary care center and who were not prescribed routine postoperative antibiotics. Duration of time until normalization of sinus cavities and whether antibiotics were ultimately prescribed for persistent infectious signs and symptoms were recorded. Patient characteristics and findings were analyzed to determine if any of the evaluated parameters were associated with the need for postoperative antibiotics.

RESULTS

Sixty-nine patients were included in the study. Thirty-three (47.8%) did not require antibiotics during the postoperative period. The average time to sinus normalization was 8.1 weeks (range 1-24 weeks) for patients who received antibiotics and 5.7 weeks (range 1-16 weeks) for those who did not receive antibiotics (P = .066). No evaluated variables were associated with antibiotic use on univariate or multivariate analysis.

CONCLUSION

Postoperative antibiotics were not necessary to normalize infected sinus cavities for nearly half of patients with unilateral purulent CRS in this series. Further studies are needed to better delineate which patients would derive benefit from postoperative antibiotics.

LEVEL OF EVIDENCE

Level IV.

[Postoperative treatment following paranasal sinus surgery]

Postoperative care is a crucial aspect for the success of paranasal sinus interventions. Basic procedures include saline nasal wash, which should be started on the first postoperative day, topical steroids, and antibiotics in cases of infection. Medical treatment involves aspiration of secretion in the inferior meatus during the first week. Removal of scabs in the surgical field should be carried out under endoscopic control beginning at the second week. Intervals are scheduled individually. Occlusion of the nose for the time of epithelium regeneration provides a moist space in the ethmoid, which improves wound healing.

Postoperative Infection Rate and Associated Factors Following Endoscopic Sinus Surgery

OBJECTIVES

There is a paucity of data on postoperative infections after endoscopic sinus surgery and associated risk factors. Our objective was to evaluate a cohort of patients undergoing endoscopic sinus surgery (ESS) for chronic rhinosinusitis to determine which perioperative factors may be associated with infection in the 30-day postoperative period.

METHODS

A retrospective cohort study of adults who underwent ESS at a tertiary academic medical center from 2015 to 2018 was performed. The primary outcome was incidence of postoperative infection, defined by identification of sinus purulence on nasal endoscopy necessitating antibiotics within 30 days of surgery. Independent variables collated included the result of postoperative cultures and use of perioperative antibiotics, oral corticosteroids, packing, and steroid-eluting stents. Statistical analysis involved bivariate analysis to identify variables that correlated with postoperative infection and subsequent multivariate logistic regression to identify independent risk factors.

RESULTS

Three hundred seventy-eight unique ESS cases performed in 356 patients were reviewed. The mean age was 46 years (range, 18-87). The most common indication for surgery was chronic rhinosinusitis without nasal polyposis. The postoperative infection rate was 10.1%. The most commonly cultured pathogen was Staphylococcus aureus. Multivariate logistic regression analysis showed that postoperative systemic corticosteroid use was the only risk factor independently associated with infection (OR 3.47 [95% CI 1.23-9.76], P = .018).

CONCLUSION

The incidence of postoperative infection following ESS was 10.1%. The use of postoperative systemic corticosteroids independently increased the risk of infection by 3.47-fold.

The Microbiome of the Nasolacrimal System and Its Role in Nasolacrimal Duct Obstruction

PURPOSE

Acquired nasolacrimal duct obstruction (NLDO) is a common problem leading to epiphora, the pathophysiology of which remains unclear. Culture-based studies have found Staphylococcal species to be the most prevalent organisms, reported in 47% to 73% of patients with NLDO. Recently, culture-independent molecular methods of have allowed more comprehensive detailing of local microbiota. This study aims to evaluate the sinonasal and lacrimal microbiome of patients undergoing dacryocystorhinostomy for NLDO using 16S-amplicon sequencing.

METHODS

Guarded intraoperative swabs were taken from the middle meatus (MM), inferior meatus, and the opened lacrimal sac of 14 NLDO patients undergoing dacryocystorhinostomy and from the inferior meatus and MM on the contralateral unaffected side. MM swabs from 12 control patients were compared with NLDO patients.

RESULTS

Comparing microbiota at lacrimal sac to MM and inferior meatus sites reveals that the lacrimal sac microbiome is dominated by Staphylococci (36.3%) and Corynebacterium (35.8%). No significant genus differential abundance between the 3 sites, and between the ipsilateral and contralateral sinonasal swabs, and no convincing evidence of reduced alpha diversity in all comparisons. There was a statistically significant lower relative abundance of Corynebacterium (37.6% vs. 65.1%; p = 0.035) in the MM of NLDO patients compared with controls.

CONCLUSIONS

The lacrimal sac microbiome in acquired NLDO is similar to the sinonasal microbiome. The relative abundance of Corynebacterium was reduced compared with controls. These findings suggest that an altered sinonasal microbiome may be associated with NLDO, either as a consequence or a risk factor, and merits future research.The authors have demonstrated a decreased relative abundance of Corynebacterium at the middle meatus of patients with ipsilateral nasolacrimal duct obstruction (NLDO), compared with controls, and that the lacrimal sac microbiome is similar to the sinonasal microbiome. An altered microbial state may, therefore, be associated with NLDO, either as a consequence or a risk factor, and merits future research.

The Use of Postoperative Antibiotics Following Endoscopic Sinus Surgery for Chronic Rhinosinusitis: A Systematic Review and Meta-analysis

BACKGROUND

Endoscopic sinus surgery is performed for medically recalcitrant chronic rhinosinusitis. There is no universally accepted strategy regarding post-operative antibiotics despite the high rates of usage worldwide. The aim of this study was to analyse patient-reported and objective outcomes behind antibiotic use following endoscopic sinus surgery.

METHODS

A search of electronic databases was performed. Eligible randomised controlled trials (RCTs) and observational trials were included. The primary outcome was patient reported outcome measures. Secondary outcomes were local infections, endoscopy scores and adverse events. Meta-analysis was performed.

RESULTS

Of 1045 publications identified, 7 were included in the qualitative synthesis and 5 RCTs were included in meta-analysis. Antibiotic regimens varied between studies in terms of antibiotic selection, timing commenced and duration of use. Meta-analysis suggested no significant difference between placebo and antibiotics in patient reported outcome measures (standardised mean difference (SMD) -0.215, 95% confidence interval (CI) -0.637 to 0.207) or endoscopic scores (SMD -2.86, 95% CI -0.846 to 0.273). There was no consistent definition in reporting of infection; therefore, this outcome cannot be comprehensively considered. No severe adverse events were attributable to antibiotics.

CONCLUSIONS

From the studies analysed, there is no level 1 evidence to suggest that antibiotics improved patient outcomes following sinus surgery. However, there was significant heterogeneity in outcome measures and no clear data exists regarding the effects of antibiotics on postoperative infections. The available evidence at present is not enough to make a recommendation in either direction. Further designed larger RCTs are required to investigate these questions in more detail.

Infection After Endoscopic Dacryocystorhinostomy: Incidence and Implications

BACKGROUND

Endoscopic dacryocystorhinostomy (EN-DCR) is an increasingly common procedure performed by otolaryngologists. While EN-DCR has a high rate of success at relieving blockage of the lacrimal system, little is known regarding associated postoperative infection (POI) rates and risk factors.

OBJECTIVE

The purpose of this study was to identify factors associated with the occurrence of postoperative orbital and rhinologic infection in a large cohort of patients undergoing EN-DCR.

METHODS

A retrospective review of 582 patients who underwent EN-DCR was performed. All patients received antibiotic prophylaxis as a single intraoperative intravenous administration and a ten-day postoperative oral course. Clinical and demographic information was reviewed, including the occurrence of acute orbital or rhinologic infection within 30 days of surgery. Multivariable analysis was performed to identify risk factors associated with POI.

RESULTS

Fifteen of 582 patients (2.6%) developed POI following EN-DCR. The most common POI was acute rhinosinusitis (10/15, 66.7%), followed by acute dacryocystitis (2/15, 13.3%), preseptal cellulitis (2/15,13.3%), and acute bacterial conjunctivitis (1/15, 6.7%). The majority of patients (464/582, 79.7%) underwent concurrent endoscopic sinus surgery (ESS). In most cases (302/464, 65.1%), ESS was performed to address comorbid rhinosinusitis, whereas 7.8% (36/464) of patients underwent surgery to enhance surgical access to the lacrimal sac. Patients who underwent concurrent ESS were less likely to develop POI (OR: 0.17, CI: 0.04-0.80, p < 0.05). Evidence of mucopurulence at surgery increased the likelihood of POI (OR: 6.24, CI: 1.51-25.84, p < 0.05).

CONCLUSION

Mucopurulence at the time of surgery significantly increased the risk of POI, whereas concurrent ESS, performed most commonly to address comorbid rhinosinusitis, significantly decreased the risk of POI. Awareness of risk factors for POI and appropriate surgical management of concurrent rhinosinusitis can lead to reduced infectious complications after EN-DCR.

Future topical medications in chronic rhinosinusitis

BACKGROUND

Research has progressed rapidly in recent decades to better understand the etiopathogenesis and management paradigms of chronic rhinosinusitis (CRS). Although oral antibiotics often mitigate symptoms in acute CRS exacerbations, eradication of polymicrobial biofilms and multidrug-resistant bacteria remains a challenge. The goal of this review is to summarize and discuss the potential and pitfalls of topical medications in the treatment of CRS.

METHODS

A related literature review was performed using PubMed and Scopus, with only the English database included.

RESULTS

The main therapies were selected and separated in sections. Details regarding future topical treatments of CRS were summarized and discussed.

CONCLUSION

The ease of access of the sinonasal mucosa positions CRS as a disease with high potential for local topical treatment. The ultimate adoption of topical agents will require continued expansion of our understanding of novel local targets in CRS as well as improved methods to deliver and retain the drug of interest at the site of activity.

The microbiome of the upper respiratory tract in health and disease

The human upper respiratory tract (URT) offers a variety of niches for microbial colonization. Local microbial communities are shaped by the different characteristics of the specific location within the URT, but also by the interaction with both external and intrinsic factors, such as ageing, diseases, immune responses, olfactory function, and lifestyle habits such as smoking. We summarize here the current knowledge about the URT microbiome in health and disease, discuss methodological issues, and consider the potential of the nasal microbiome to be used for medical diagnostics and as a target for therapy.

In vitro characteristics of an airway barrier-disrupting factor secreted by Staphylococcus aureus

BACKGROUND

Staphylococcus aureus is a major contributor to the pathophysiology of chronic rhinosinusitis (CRS). Previous research has shown that S. aureus-secreted products disrupt the airway barrier.

METHODS

S. aureus ATCC 13565 and 25923 strains were grown at exponential, postexponential, and stationary phases. Microbial conditioned media (CM) was collected from the cultures and ultrafiltered (UF). Liquid chromatography-electrospray ionization tandem mass spectrometry (LC-ESI-MS/MS) was performed on the UF-CM. UF-CM was subjected to heat and protease treatment, size fractionation, and ultracentrifugation (UC) separation. Human nasal epithelial cells grown at air-liquid interface (HNEC-ALI) cultures were exposed to purified alpha hemolysin (Hla), staphylococcal enterotoxin A (SEA), lipoteichoic acid (LTA), and UF-CM. Barrier function outcomes were measured by transepithelial electrical resistance (TEER) and apparent permeability (Papp). UC fraction exposed cultures were subjected to immunofluorescence microscopy for tight junction (TJ) protein zonula occludens-1 (ZO-1).

RESULTS

LC-ESI-MS/MS identified 107 proteins, with Hla being most abundant. Hla, SEA, and LTA did not alter the HNEC-ALI barrier as measured by TEER or Papp. Barrier disruption caused by UF-CM peaked in the postexponential phase, was sensitive to heat and protease treatment, >30-kDa in size, and enriched in the UC fraction. HNEC-ALI exposed to UF-CM and UC demonstrated loss of ZO-1 localization.

CONCLUSION

These results suggest that the S. aureus factor responsible for TJ disruption in HNEC-ALI cultures is either a protein-macromolecule or a combination of secreted factors. The product is enriched in the UC fraction, suggesting it is associated with large structures such as membrane components or vesicles.

Inflammatory immune response in rabbits with Staphylococcus aureus biofilm-associated sinusitis

Background

Staphylococcus aureus is the most commonly isolated bacterium from patients with surgically recalcitrant chronic rhinosinusitis (CRS). Understanding the immune responses to S aureus biofilms will provide insights into how the host response may be manipulated by therapeutic agents to improve the chances of successfully preventing and treating these infections. In this study, we investigated the inflammatory immune response in a rabbit model of S aureus biofilm–related sinusitis by analyzing the levels of some major inflammatory cytokines.

Methods

Eighteen New Zealand white rabbits were randomly divided into 3 groups: a blank‐control group; a negative‐control group; and a model group. Four weeks after the biofilm‐associated sinusitis models were established, the sinus mucosa was harvested and examined using hematoxylin‐eosin (H&E) staining, scanning electron microscopy (SEM), reverse transcription polymerase chain reaction (RT‐PCR), and western blotting. The expression levels of inflammatory cytokines were analyzed statistically.

Results

Interleukin (IL)‐1β, IL‐8, and tumor necrosis factor (TNF)‐α expression levels were significantly higher in the model group than in the blank‐control group (p < 0.05); mRNA levels were increased by 1600%, 230%, and 130%, respectively, and the protein levels were increased by 180%, 100%, and 100%, respectively. In contrast, IL‐4 and IL‐5 mRNA levels were reduced by 44% and 70%, respectively, compared with the blank‐control group (p < 0.05).

Conclusion

S aureus biofilms in the rabbit maxillary sinus mucosa were associated with increased IL‐1β, IL‐8, and TNF‐α expression, and decreased IL‐4 and IL‐5 expression.

The effect of medical treatments on the bacterial microbiome in patients with chronic rhinosinusitis: a pilot study

BACKGROUND

Antibiotics and corticosteroids are prescribed to patients with chronic rhinosinusitis (CRS) to reduce bacterial burden and mucosal inflammation. Unfortunately, clinical improvement is often short-lived and symptoms frequently recur following cessation of treatment. The impact of these systemic therapies on bacterial communities is not well understood. Improved knowledge of how medical therapies influence the intranasal ecosystem may allow for more effective prescribing and the development of more targeted treatments.

METHODS

Twenty patients with CRS were randomized to receive either doxycycline 100 mg twice daily or prednisone 30 mg once daily for 7 days. A further 6 patients with CRS were recruited as untreated controls. Swabs were taken immediately before and after the study period. Symptom scores (22-item Sino-Nasal Outcome Test [SNOT-22]) were recorded. Bacterial communities were characterized using 16S ribosomal RNA (rRNA) gene-targeted amplicon sequencing. Bacterial abundance was estimated using quantitative polymerase chain reaction (PCR) of 16S rRNA gene copies.

RESULTS

Bacterial profiles were dominated by members of the genera Corynebacterium and Staphylococcus. Patients treated with either doxycycline or prednisone had variable and unpredictable changes in communities. The average relative abundance of Propionibacterium increased after treatment in the doxycycline treatment group, and Corynebacterium reduced in the prednisone group. Significant differences in clinical scores, bacterial community richness, diversity, and bacterial abundance were not seen after treatment.

CONCLUSION

The short-term response of bacterial communities to antibiotic or corticosteroid therapy is unpredictable. This study suggests that the use of systemic therapy in patients with stable CRS should be rationalized to minimize antibiotic-associated morbidity and bacterial dysbiosis.

Antibiotic use patterns in endoscopic sinus surgery: a survey of the American Rhinologic Society membership

BACKGROUND

There is a paucity of data supporting antibiotic use in endoscopic sinus surgery (ESS). The objective of this study is to determine perioperative antibiotic use patterns and factors which influence use in ESS.

METHODS

An online-based survey was distributed to members of the American Rhinologic Society (ARS). Outcomes included timing of perioperative antibiotic use, practice environment, years of experience, and patient factors that influenced antibiotic use.

RESULTS

There were 204 responses (response rate 18.3%); 36.8% of respondents were in academic positions, 32.8% were in private practice, and 30.4% were in academic-affiliated private practice; 20.6% routinely gave preoperative antibiotics, most commonly to reduce bacterial burden (59.5%) and mucosal inflammation (59.5%); 54.4% routinely gave intraoperative antibiotics, most commonly to reduce the risk of postoperative infection (63.1%); 62.3% routinely gave postoperative antibiotics, citing the need to reduce the risk of postoperative infection (75.6%). Diagnosis influenced postoperative antibiotic use in 63.0%. Preoperative antibiotics were more likely to be prescribed by respondents with more than 5 years of experience (odds ratio [OR] 2.97; 95% confidence interval [CI], 1.04 to 8.54; p = 0.043). Compared to private practitioners, academicians were more likely to give intraoperative antibiotics (OR 2.68; 95% CI, 1.39 to 5.17; p = 0.003), but not preoperative or postoperative antibiotics. Use of nonabsorbable packing was significantly associated with use of postoperative antibiotics (OR 2.01; 95% CI, 1.07 to 3.77; p = 0.031).

CONCLUSION

This study demonstrates the significant variation in perioperative antibiotic use among otolaryngologists. These results provide support for the establishment of evidence-based practice guidelines for perioperative antibiotic use in ESS.

Staphylococcus Aureus V8 protease disrupts the integrity of the airway epithelial barrier and impairs IL-6 production in vitro

OBJECTIVE

Staphylococcus aureus (S. aureus) infection is known to contribute to the severity and recalcitrance of chronic rhinosinusitis (CRS), and its secreted products have been shown to alter the airway barrier. Extracellular proteases secreted by S. aureus are thought to be important in epithelial infection and immune evasion; however, their effect on airway mucosal barrier function is not known.

METHODS

To investigate the impact of extracellular proteases on airway epithelial integrity, the purified S. aureus proteases V8 protease, Staphopain A, Staphopain B, Exfoliative toxin A, and serine protease-like A-F were applied to human nasal epithelial cell air-liquid interface (HNEC-ALI) cultures. Transepithelial electrical resistance (TEER), permeability (Papp) measurements, and immuno-localization of the tight junction proteins claudin-1 and ZO-1 were used to assess barrier integrity. Effects of the proteases on inflammation and cell viability were measured using interleukin-6 (IL-6) ELISA and a lactate dehydrogenase assay.

RESULTS

Application of V8 protease to HNEC-ALI cultures caused a significant concentration and time-dependent decrease in TEER (22.67%, P < 0.0001), a reciprocal Papp increase (20.14-fold, P < 0.05), and a discontinuous ZO-1 immuno-localization compared to control. IL-6 production was significantly reduced in V8 protease-treated cells (153.5 pg/mL, P = 0.0069) compared to control (548.3 pg/mL), whereas no difference in cell viability was observed.

CONCLUSION

S. aureus V8 protease causes dysfunction of mucosal barrier structure and function indicative of a leaky barrier. A reduction in IL-6 levels suggests that the mucosal immunity is impaired by this protease and thus has the potential to contribute to CRS recalcitrance.

LEVEL OF EVIDENCE

NA. Laryngoscope, 128:E8-E15, 2018.

Bacterial Pathogens and the Microbiome

Bacterial pathogens and microbiome alterations can contribute to the initiation and propagation of mucosal inflammation in chronic rhinosinusitis (CRS). In this article, the authors review the clinical and research implications of key pathogens, discuss the role of the microbiome, and connect bacteria to mechanisms of mucosal immunity relevant in CRS.

Evidence of microbiota dysbiosis in chronic rhinosinusitis

BACKGROUND

Despite considerable research, the pathogenesis of chronic rhinosinusitis (CRS) remains poorly understood. Potential microbial roles in the etiology or progression of CRS have long been hypothesized, yet few specific associations have been identified. In this study we investigate associations between patterns in resident bacterial communities and clinical variants of CRS.

METHODS

Bacterial communities were assessed in 94 patients with extensive bilateral CRS undergoing endoscopic sinus surgery (ESS) and 29 controls undergoing ESS for indications other than CRS. Patients were grouped on the basis of phenotypic variants (with or without polyposis) and clinical parameters, including asthma and cystic fibrosis. Bacterial communities were characterized via 16S rRNA gene amplicon sequencing, and quantified by quantitative polymerase chain reaction.

RESULTS

Controls and idiopathic CRS subjects tended to be dominated by members of the genera Corynebacterium and Staphylococcus, together with lower abundances of several other genera, including Streptococcus, Moraxella, and Haemophilus. Aberrant (dysbiotic) bacterial assemblages (with changes in community membership and structure, reduced diversity, and increased bacterial load) and increased inter- and intrasubject variability were more common in subjects with comorbidities such as asthma and cystic fibrosis. Dysbiotic communities were variably dominated by members of the genera Staphylococcus, Streptococcus, Haemophilus, Pseudomonas, Moraxella, or Fusobacterium.

CONCLUSION

Bacterial community dysbiosis was more apparent than specific associations with examined phenotypes or endotypes, and may play a role in the pathogenesis or influence the severity of CRS. Reductions in several common core bacterial taxa, increased inter- and intrasubject variability, reduced bacterial diversity, and increased bacterial load characterized aberrant bacterial communities in CRS.

Changes in the bacterial microbiome of patients with chronic rhinosinusitis after endoscopic sinus surgery

BACKGROUND

Endoscopic sinus surgery (ESS) improves symptoms for many chronic rhinosinusitis (CRS) patients by enlarging the size of sinus ostia, improving mucociliary clearance, and facilitating access for topical therapies. However, the effect of surgery on the sinonasal microbiota remains poorly understood. This study examined changes in bacterial communities in CRS patients before and after surgery.

METHODS

Swab samples were taken from the middle meatus of 23 patients undergoing ESS. Follow-up swabs were taken in clinic (mean 120 days postsurgery). Symptom scores and antibiotic use were recorded. Bacterial communities were characterized using 16s ribosomal RNA (rRNA) gene-targeted amplicon sequencing and bacterial abundance was measured using quantitative polymerase chain reaction (PCR). Coexisting asthma, aspirin sensitivity, antibiotic use, and presence of polyps were controlled for.

RESULTS

Unpredictable shifts in bacterial community composition were seen postoperatively. ESS was associated with increased bacterial richness. Many taxa had changes in average relative abundance and prevalence. Staphylococcus was the only dominant taxa to increase significantly in relative abundance (p = 0.002). Changes in bacterial communities were driven more by intersubject variability (p = 0.007) than other study factors. Finegoldia, a minority taxon, was associated with a reduction in abundance following ESS, increases in patients with higher symptoms scores, and reductions in patients with reduced total bacterial burden.

CONCLUSION

This study documented changes in bacterial composition and abundance in the middle meatus following ESS. The complexity of these changes reflects the variability between patients. Modern molecular techniques highlight the currently limited knowledge of the impact of therapies on the microbiology of CRS.

Investigation of bacterial repopulation after sinus surgery and perioperative antibiotics

BACKGROUND

Endoscopic sinus surgery (ESS) enjoys high success rates, but repopulation with pathogenic bacteria is 1 of the hallmarks of poorer outcomes. There are many hypothesized sources of repopulating bacteria; however, this process remains largely unexplored. This study examined changes in the sinus microbiome after ESS and medical therapies to identify potential sources for postsurgical microbial repopulation.

METHODS

Samples from the anterior nares, ethmoid sinus, and nasopharynx were taken at the time of surgery from 13 subjects undergoing ESS for chronic rhinosinusitis (CRS). Patients were treated postoperatively with 2 weeks of oral antibiotics and saline rinses. The ethmoid sinus was sampled at 2 and 6 weeks postoperatively; microbiota were characterized using quantitative polymerase chain reaction (qPCR) and 16S ribosomal RNA (rRNA) gene sequencing. The Morisita-Horn beta-diversity index (M-H) was used to compare similarity between samples.

RESULTS

The bacterial burden of the ethmoid was higher 2 weeks postoperatively than 6 weeks postoperatively (p = 0.01). The 6-week samples most closely represented the anterior nares and ethmoid at surgery (M-H = 0.58 and 0.59, respectively), and were least similar to the nasopharynx (M-H = 0.28). Principal coordinates analysis (PCoA) plots illustrate that the ethmoid microbiota temporarily shifted after surgery and antibiotics but returned toward baseline in many subjects.

CONCLUSION

Bacterial communities colonizing the ethmoid 6 weeks postoperatively were most similar to anterior nasal cavity and pretreatment sinus microbial profiles, indicating a high degree of resilience in the sinonasal microbiome of most subjects. Interestingly, surgery and postoperative antibiotic therapy does not appear to reduce bacterial burden, but rather, shifts the microbial consortia.

Impact of cigarette smoking on the middle meatus microbiome in health and chronic rhinosinusitis

BACKGROUND

Although cigarette smoking aggravates chronic rhinosinusitis (CRS), a detailed examination of the sinus microbiota in CRS and its clinical subtypes has yet to be performed in relation to history of smoking. Consequently, we examined associations between smoking history and sinonasal microbiome alterations in both CRS and non-CRS populations.

METHODS

Middle meatus swabs collected during endoscopic sinus surgery were analyzed by analysis of 16S ribosomal RNA (rRNA) sequences. Multiple analysis of variance tests were performed to determine whether microbiome composition varied with smoking history and other clinical/demographic covariates associated with CRS subtypes.

RESULTS

A total 70 CRS patients and 31 control subjects were analyzed. In a univariate analysis, smoking (p = 0.04), preoperative antibiotics (p = 0.03), and purulence (p = 0.0002) were significantly associated with the genus-level composition of the middle meatus microbiota. When included in a multivariable model, smoking was found to have significant interactions with CRS (p = 0.02), polyposis (p = 0.03), purulence (p = 0.0004), and use of saline rinses (p = 0.05). Diverse bacterial taxa differed significantly in abundance between never-smokers and current/former smokers, as well as between different CRS subtypes.

CONCLUSION

Substantial changes in sinus bacterial colonization were observed in smokers and nonsmokers. Although the microbiota of both CRS and non-CRS subjects were altered with smoking history, different bacterial taxa were affected by smoking in the 2 patient groups. Thus, the effects of smoking on the sinus microbiota are likely to be modified by physiological and immunological functions of the underlying sinus mucosa.

A simple animal model of Staphylococcus aureus biofilm in sinusitis

BACKGROUND

Previous research suggested that the biofilm of Staphylococcus aureus contributes greatly to the recalcitrant nature of chronic rhinosinusitis (CRS). However, the lack of a simple and stable animal model limited further study in this field. The aim of this study was to create a convenient animal model of S. aureus biofilms in the maxillary sinus of rabbit.

METHODS

New Zealand white rabbits were used as model animals and incised vertically along the median line of the nasal dorsum to expose the anterolateral wall of maxillary sinus, on which a 1.5-mm-diameter hole was drilled to enter the sinus cavity. Through the hole, a piece of gelatin sponge was inserted and then inoculated bacterial suspension into the maxillary sinus. One to 8 weeks after the surgery, the sinus mucosa were harvested and examined with scanning electron microscopy (SEM) and hematoxylin and eosin (H&E) staining.

RESULTS

All rabbits tolerated the surgical procedures and had developed sinusitis by the time they were killed. SEM revealed that biofilms were presented in 100% of rabbits who had bacteria infected for ≥2 weeks, during which the ciliated epithelial cells were encapsulated and gradually destroyed. H&E staining revealed morphological changes of the epithelial cells and infiltration of inflammatory cells in the subepithelial layer, which showed a strong correlation with the results of SEM.

CONCLUSION

This biofilm model of sinusitis avoids excessive damage to the nasal cavity and sinuses of the rabbits. It may be a desirable animal model for studying the pathogenesis and eradication strategies of bacterial biofilms in sinusitis.

When and how should we treat biofilms in chronic sinusitis?

PURPOSE OF REVIEW

Biofilms have been observed on the sinus mucosa of patients with chronic rhinosinusitis and are associated with poor clinical outcomes after surgery. This article summarizes the recent studies which describe the efficacy of treating biofilms in chronic rhinosinusitis.

RECENT FINDINGS

Biofilms are polymicrobial communities comprised of bacteria that tend to be more antibiotic-resistant than when in planktonic forms. Antibiotic therapy against biofilms is usually associated with relapse following cessation of treatment and may also have an adverse effect on normal commensal microflora. Surfactants can improve clinical symptoms, but their use has been limited by side effects. Other treatment modalities that physically remove or disrupt biofilms, such as ultrasound, have shown some efficacy in small trials. The impact of surgery on biofilms has not been extensively investigated.

SUMMARY

The nature of biofilms makes their removal difficult. No currently available treatment directed against them has demonstrated lasting efficacy.

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.

Small-colony variants and phenotype switching of intracellular Staphylococcus aureus in chronic rhinosinusitis

BACKGROUND

Chronic rhinosinusitis (CRS) has been linked to the gram-positive bacteria Staphylococcus aureus (S. aureus) in its biofilm or intracellular forms. Recent evidence suggests that S. aureus also exists in a small-colony variant (SCV) form as a mechanism of altering its virulence capabilities. The aim of this study was to investigate the presence of SCVs in sinonasal mucosa of CRS patients and whether the phenomenon of phenotype switching can be applied to intracellular epithelial infections.

METHODS

Sinonasal specimens were examined for the presence of intramucosal S. aureus and characterized to the strain level. An airway epithelial cell culture infection model was utilized to investigate whether bacteria were capable of alterations in virulence phenotype.

RESULTS

Intramucosal organisms harvested from sinonasal biopsies demonstrate phenotypic growth patterns and lack of coagulase activity consistent with SCVs. Intracellular infection of airway epithelial cell cultures with S. aureus led to decreased secretion of enterotoxins and phenotypic growth alterations consistent with SCVs.

CONCLUSIONS

Regulation of S. aureus virulence factors is a dynamic process, and exposure to the intracellular environment appears to provide the necessary conditions to enable these alterations in an attempt for the bacterium to survive and persist within host tissues. Further work is required to ascertain whether SCVs in CRS hold a clinically relevant pathogenic role in recalcitrant disease.

Liposome-encapsulated ISMN: a novel nitric oxide-based therapeutic agent against Staphylococcus aureus biofilms

Background

Staphylococcus aureus in its biofilm form has been associated with recalcitrant chronic rhinosinusitis with significant resistance to conventional therapies. This study aims to determine if liposomal-encapsulation of a precursor of the naturally occurring antimicrobial nitric oxide (NO) enhances its desired anti-biofilm effects against S. aureus, in the hope that improving its efficacy can provide an effective topical agent for future clinical use.

Methodology

S. aureus ATCC 25923 biofilms were grown in-vitro using the Minimum Biofilm Eradication Concentration (MBEC) device and exposed to 3 and 60 mg/mL of the NO donor isosorbide mononitrate (ISMN) encapsulated into different anionic liposomal formulations based on particle size (unilamellar ULV, multilamellar MLV) and lipid content (5 and 25 mM) at 24 h and 5 min exposure times. Biofilms were viewed using Live-Dead Baclight stain and confocal scanning laser microscopy and quantified using the software COMSTAT2.

Results

At 3 and 60 mg/mL, ISMN-ULV liposomes had comparable and significant anti-biofilm effects compared to untreated control at 24 h exposure (p = 0.012 and 0.02 respectively). ULV blanks also had significant anti-biofilm effects at both 24 h and 5 min exposure (p = 0.02 and 0.047 respectively). At 5 min exposure, 60 mg/mL ISMN-MLV liposomes appeared to have greater anti-biofilm effects compared to pure ISMN or ULV particles. Increasing liposomal lipid content improved the anti-biofilm efficacy of both MLV and ULVs at 5 min exposure.

Conclusion

Liposome-encapsulated “nitric oxide” is highly effective in eradicating S. aureus biofilms in-vitro, giving great promise for use in the clinical setting to treat this burdensome infection. Further studies however are needed to assess its safety and efficacy in-vivo before clinical translation is attempted.

Bacteriophage Reduces Biofilm of Staphylococcus Aureus Ex Vivo Isolates from Chronic Rhinosinusitis Patients

Background

Staphylococcus aureus is the most common organism in recalcitrant chronic rhinosinusitis (CRS) and is often resistant to traditional antibiotic therapy. Bacteriophages (“phages”) are a potential candidate for a new, effective therapy. For phages to be useful in setting CRS, two minimum requirements must be presented: (1) phages must be effective against S. aureus biofilms and (2) phages must have a broad spectrum of activity. This study aimed to assess the in vitro activity of a phage cocktail (CockTail of Staphylococcus aureus specific bacteriophage [CT-SA]) against S. aureus biofilms and a broad panel of strains isolated from patients with CRS.

Methods

The study examined 66 clinical isolates (CIs) of S. aureus. All isolates were tested for the susceptibility to phage lysis by spotting CT-SA onto bacterial lawns. To measure its effect on S. aureus biofilms, a minimum biofilm eradication concentration assay was used, using five S. aureus isolates. Biofilms of these isolates were grown, treated with CT-SA for 48 hours, fluorescently stained, and viewed using confocal scanning laser microscopy.

Results

CT-SA lysed 62 of 66 (94%) CIs of S. aureus. CT-SA treatment yielded significant reductions in biofilm mass for 4/5 CIs tested and for ATCC 25923. Challenge of S. aureus with a single phage resulted in the emergence of bacteriophage-insensitive mutants (BIM) with a frequency of 10−7, and challenge with CT-SA completely prevented their development.

Conclusion

This study indicates that phage cocktail CT-SA can effectively eliminate S. aureus, in planktonic and biofilm forms, from the great majority of CIs from this hospital setting. In addition, its potential effect in preventing the emergence BIMs was a established. Thus, CT-SA has the potential to treat S. aureus infection and biofilm in CRS patients.

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.

Is nasal steroid spray bottle contamination a potential issue in chronic rhinosinusitis?

BACKGROUND

Intranasal steroids are the first line of treatment for chronic rhinosinusitis. Although contamination of adjunctive devices (e.g. irrigation bottles) has been much investigated, little is known about nasal contamination of the metered-dose spray bottles used to deliver intranasal steroids, and the potential influence on disease chronicity.

METHODS

Twenty-five prospectively recruited patients with stable chronic rhinosinusitis underwent microbiological analysis of their nasal vestibule and middle meatus and also of their steroid bottle tip and contents. Additionally, bottle tips were inoculated in vitro with Staphylococcus aureus and various sterilisation techniques tested.

RESULTS

For 18 of the 25 (72 per cent) patients, both nasal and bottle tip swabs grew either Staphylococcus aureus or coagulase-negative staphylococci. Staphylococcus aureus was cultured from 7 of the 25 (28 per cent) patients, and 5 of these 7 had concomitant bacterial growth from both nose and steroid bottle. Thus, the cross-contamination rate was 71 per cent for Staphylococcus aureus infected patients and 20 per cent overall. Sterilisation was effective with boiling water, ethanol wipes and microwaving, but not with cold water or dishwashing liquid.

CONCLUSION

Nasal steroid spray bottle tips can become contaminated with sinonasal cavity bacteria. Simple sterilisation methods can eliminate this contamination. Patient education on this matter should be emphasised.

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.

The bacteriology of chronic rhinosinusitis and the pre-eminence of Staphylococcus aureus in revision patients

BACKGROUND

The role of bacteria in the etiopathogenesis of chronic rhinosinusitis (CRS) remains an area of interest. The impact of surgery and factors such as the presence of polyps, asthma, and aspirin sensitivity on the bacterial state are poorly understood. To determine the effect of these factors, this study examines the culture results from a large cohort of CRS patients.

METHODS

This retrospective study used the culture results from 513 CRS patients, which were analyzed for species growth and compared to factors such as previous surgery, presence of polyps, aspirin sensitivity, and asthma. Univariate and multivariate logistic regression models were used for statistical analysis.

RESULTS

Eighty-three percent (83%) of patients had a positive culture result. The average number of isolates detected per patient was 0.95. S. aureus was the most frequently cultured organism (35%), followed by P. aeruginosa (9%), Haemophilus spp. (7%), and S. pneumonia (5%). Revision patients were more likely to grow S. aureus (p = 0.001), P. aeruginosa (p = 0.044) and have a positive culture (p = 0.001). Asthma was correlated with a positive culture (p = 0.039). No difference was determined between polyp and nonpolyp patients for any of the bacterial outcomes.

CONCLUSION

This study highlights important factors in the bacteriology of CRS patients. S. aureus was the most prevalent species identified in our cohort, followed by P. aeruginosa. S. aureus rates of isolation were also significantly higher in patients undergoing revision surgery. No association was found between the presence of nasal polyposis and culture rates.

Intramucosal bacterial microcolonies exist in chronic rhinosinusitis without inducing a local immune response

BACKGROUND

Although chronic rhinosinusitis (CRS) causes very significant morbidity, much about its pathogenesis remains uncertain. Recent studies have identified polymicrobial biofilms on the surface of sinus mucosa and Staphylococcus aureus within the sinus mucosa of patients with CRS, both with and without nasal polyps. The pathogenic implications of intramucosal bacteria in CRS are unknown. This study was designed to determine the prevalence and species of bacterial colonies within the sinus mucosa of adult patients with and without CRS and to describe the relationship of these bacterial colonies to the host immune response.

METHODS

Sinus mucosa from patients with and without CRS was examined using Gram and Giemsa staining, immunohistochemistry, bacterial culture, and fluorescence in situ hybridization techniques.

RESULTS

Bacterial microcolonies were observed within the mucosa in 14 of 18 patients with CRS. In 10 of these patients colonies were positively identified as S. aureus. Staphylococcal microcolonies were observed at a lower level (1 of 8 patients) in normal sinus mucosa. There was no correlation between detection of S. aureus on the mucosal surface and microcolonization of the mucosa. Surprisingly, there was no evidence of an immune reaction to microcolonies. Indeed, fewer T lymphocytes (p = 0.03) and eosinophils (p = 0.03) were counted immediately surrounding the microcolonies compared with uninfected areas of the same tissue.

CONCLUSION

Bacterial microcolonies are prevalent within paranasal sinus mucosa and are commonly S. aureus. These microcolonies do not provoke immune detection and may represent a phenotype that actively evades host immunity. This may underpin the recalcitrance of CRS to antibiotic therapy. These findings challenge classic views of both infection and mucosal immunity in human chronic disease. The presence of intramucosal bacteria in samples of normal sinus mucosa also questions the sensitivity of detecting nasal carriage of pathogens by swabbing the surface of the anterior nares.

Gene expression differences in nitric oxide and reactive oxygen species regulation point to an altered innate immune response in chronic rhinosinusitis

BACKGROUND

The complex interplay between host, environment, and microbe in the etiopathogenesis of chronic rhinosinusitis (CRS) remains unclear. This study focuses on the host-microbe interaction, specifically the regulation of nitric oxide (NO) and reactive oxygen species (ROS) against the pathogenic organism Staphylococcus aureus (S. aureus). NO and ROS play crucial roles in innate immunity and in the first-line defense against microbial invasion.

METHODS

Sinonasal tissue samples were harvested from CRS and control patients during surgery. CRS patients were classified S. aureus biofilm-positive (B+) or biofilm-negative (B-) using fluorescence in situ hybridization and clinically as polyp-positive (P+) or polyp-negative (P-). Samples were assessed using an NO polymerase chain reaction (PCR) array containing 84 genes involved in NO and ROS regulation, and gene expression of all subgroups were compared to each other.

RESULTS

Twenty-three samples were analyzed with 31 genes significantly changed, the greatest seen in the B+P+ CRS patients. Four genes consistently displayed differential expression between the groups including the cytoprotective oxidation resistance 1 (OXR1) and peroxiredoxin 6 (PRDX6), neutrophil cytosolic factor 2 (NCF2), and the prion protein (PRNP) genes.

CONCLUSION

Alteration in gene expression points to impaired innate immune responses differing among CRS subgroups based on S. aureus biofilm and polyp status. The consistent alteration of 4 genes among distinct groups demonstrates that S. aureus biofilms and polyps are associated with specific changes in gene expression. Further studies are required to validate these findings in a wider cohort of patients and correlate this to protein expression and disease manifestation.

Regulation of murine sinonasal cilia function by microbial secreted factors

BACKGROUND

Chronic rhinosinusitis is a multifactorial disease resulting in impaired mucociliary clearance. Recent literature suggests that different bacterial species are associated with varied disease severity. We examined the immediate effect of microbial secreted factors on sinonasal ciliary function.

METHODS

Murine primary sinonasal cultures were established in an air-liquid interface (ALI). Bacterial supernatants were isolated from H. influenza, S. pneumoniae, S. aureus, and P. aeruginosa cultures, as well as co-cultures of H. influenza/S. pneumoniae and S. aureus/P. aeruginosa. Controlling for pH and osmolarity, supernatants were administered at 50% concentration to the apical surface of the ALI culture. Basal ciliary beat frequency (CBF) was recorded for 20 minutes, at 5-minute intervals. Control groups were treated with culture broth. At minimum, experiments were performed in triplicate. Stimulated CBF was recorded after mechanical stimulation via short bursts of pressurized air (55 mmHg).

RESULTS

All supernatants reduced basal CBF. S. pneumoniae and P. aeruginosa caused significant reduction in CBF at all time points, with the largest decrease of -46.3 ± 1.6% (p < 0.001) for S. pneumoniae and -27.1 ± 2.8% (p < 0.001) for P. aeruginosa. S. aureus caused the basal CBF to decline by -33.0 ± 2.8% (p < 0.001) at 5 minutes, which reversed by 20 minutes. Overall, H. influenza yielded the least change in CBF (-20.0 ± 2.8%, p < 0.002). Co-cultures (H. influenza/S. pneumoniae and S. aureus/P. aeruginosa) resulted in delayed CBF reduction compared with monocultures. P. aeruginosa also blunted stimulated CBF (p < 0.02).

CONCLUSION

Results demonstrated acute decreases in murine sinonasal CBF after exposure to bacterial supernatants. Moreover, P. aeruginosa resulted in diminished ciliary stimulation capacity.

Microbiome complexity and Staphylococcus aureus in chronic rhinosinusitis

OBJECTIVES/HYPOTHESIS

The aim of this study was to compare microbiological culture-based and culture-independent (16S rRNA gene sequencing) methodologies for pathogen identification in chronic rhinosinusitis (CRS) patients. We hypothesized that bacterial culture and DNA sequencing would yield largely concurrent results, although sequencing would detect greater bacterial diversity, and the sinonasal microbiomes of CRS patients would differ in composition and diversity compared with non-CRS controls.

STUDY DESIGN

Cross-sectional observational study.

METHODS

Middle meatus swabs from CRS patients collected during endoscopic sinus surgery were analyzed by both clinical culture and broad-range analysis of 16S rRNA gene pyrosequences.

RESULTS

A total of 21 swab samples from 15 CRS patients and five non-CRS controls were analyzed. One CRS patient was also swabbed 3 weeks postoperatively due to evidence of purulence during a clinical visit. All subjects had positive bacterial cultures, with a mean of 2.8 isolates per subject. The most prevalent cultivars were coagulase-negative staphylococci (15/20 specimens, 75%), Staphylococcus aureus (10/20, 50%), and Propionibacterium acnes (6/20, 30%). Among 57,407 pyrosequences generated, the most prevalent were from coagulase-negative staphylococci (21/21 specimens, 100%), Corynebacterium spp (18/21, 85.7%), P acnes (16/21, 76.2%), and S aureus (14/21, 66.7%). Bacterial diversity correlated with recent antibiotic use, asthma, prior sinus surgery, and relative abundance of S aureus.

CONCLUSIONS

DNA pyrosequencing revealed greater biodiversity than culture, although in most cases culture results represented a subset of the abundant DNA sequence types. CRS patients were characterized by altered microbial composition (P = .02) and greater abundance of S aureus (P = .03).

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.

Antimicrobial properties of a chitosan dextran-based hydrogel for surgical use

A chitosan dextran-based (CD) hydrogel, developed for use in endoscopic sinus surgery, was tested for antimicrobial activity in vitro against a range of pathogenic microorganisms. The microdilution technique was used to determine minimum inhibitory, minimum bactericidal, and minimum fungicidal concentrations. In addition, the time-kill efficacy of CD hydrogel was determined for two bacterial species. Scanning and transmission electron microscopy were carried out to elucidate the antimicrobial mechanism of this compound. CD hydrogel was found to be effective against Staphylococcus aureus, Streptococcus pyogenes, Escherichia coli, and Clostridium perfringens at its surgical concentration of 50,000 mg/liter. Minimum bactericidal concentrations ranged from 2,000 to 50,000 mg/liter. Dextran aldehyde (DA) was found to be the antimicrobial component of the CD hydrogel with MBC ranging from 2,000 to 32,000 mg/liter. S. aureus appeared to be killed at a slightly faster rate than E. coli. Candida albicans and Pseudomonas aeruginosa were more resistant to CD hydrogel and DA. Scanning and transmission electron microscopy of E. coli and S. aureus incubated with CD hydrogel and DA alone revealed morphological damage, disrupted cell walls, and loss of cytosolic contents, compatible with the proposed mode of action involving binding to cell wall proteins and disruption of peptide bonds. Motility and chemotaxis tests showed E. coli to be inhibited when incubated with DA. The antibacterial activity of CD hydrogel may make it a useful postsurgical aid at other body sites, especially where there is a risk of Gram-positive infections.