Airway Pathogens Research Articles

Inducible Costimulator Contributes to Methicillin-Resistant Staphylococcus aureus Pneumonia.

Staphylococcus aureus is a major cause of both community- and healthcare-acquired pneumonias. Inducible costimulator (ICOS) is part of the CD28 family of proteins and is a target for immune checkpoint therapy. We found ICOS highly expressed on activated CD4 cells in response to S. aureus. In the absence of ICOS, mice had improved survival in a pneumonia model with the methicillin-resistant Staphylococcus aureus (MRSA) strain USA300 and significant reductions in bacterial burden in a nonlethal acute pneumonia model. Infected Icos-/- mice had major reductions in several proinflammatory cytokines, neutrophils, inflammatory monocytes, and eosinophils compared to infected wild-type mice, while there was improved expression of CD11c and macrophage receptor with collagenous structure on the surface of alveolar macrophages. Early during infection infected Icos-/- mice had increased numbers of alveolar macrophages and expression of several surface markers on alveolar macrophages and neutrophils. ICOS signaling also contributed to the pathogenesis of the airway pathogens Klebsiella pneumoniae, Pseudomonas aeruginosa, and Streptococcus pneumoniae, and neutralizing antibody to ICOS led to improved clearance of S. aureus from the airway. Our results indicate that ICOS plays a significant role in orchestrating the innate immune response to S. aureus and other airway pathogens, and could be a potential immunomodulatory target to attenuate S. aureus-related immunopathology.

Stem Cell Therapy for COPD: Where are we?

Over the last year I have had several patients ask me about stem cell therapy for chronic obstructive pulmonary disease (COPD). There are clinics currently offering this therapy, (typically at exorbitant out of pocket cost to the patient), even though there are no phase III randomized controlled trials or Food and Drug Administration approval. There have been several phase I clinical trials, mostly looking at safety, and a handful of small phase II clinical trials that essentially have been negative. Despite this, there remains keen interest in continuing to study so-called “regenerative therapy” for COPD. Indeed, current standard therapies including bronchodilators and inhaled corticosteroids and the phosphodiesterase-4 inhibitor, roflumilast, show modest efficacy at best in reducing exacerbations and improving lung function. There has been no definitive evidence that they impact mortality. Lung volume reduction surgery is reserved often for those with severe disease and has only modest benefits. Lung transplantation is limited by availability, age restrictions, complications and rejection issues. With these limitations of standard modalities of therapy, it is attractive to pursue novel regenerative therapies that may be capable of restoring pulmonary function and structures such as airways, terminal bronchioles and alveoli. It is also postulated that by replacing these damaged cells there can be a restoration of normal immune function and a reduction in the inflammatory response to variable exposures such as cigarette smoke, air pollution and airway pathogens in susceptible individuals who develop COPD. Stem cells can differentiate into several different lung cell types such as the alveolar epithelial cells that are destroyed by cigarette smoke leading to emphysematous changes and reduced tethering of small airways causing hyperinflation and gas exchange abnormalities. Pre-clinical trials in animal models have suggested regeneration of alveolar-like structures, repair of emphysematous lungs, and reduction of inflammatory responses. The greatest success has been in acute lung injury models, however. Currently, regenerative therapies are divided into extrinsic therapeutic strategies and intrinsic cell therapy methods. There has been some work looking at the potential to bioengineer fully intact 3-D lung units that could be transplanted but this is not a likely prospect for the near future. Extrinsic cell therapy refers to infusing (or endotracheal installation) of stem cells including embryonic stem cells (ESCs), induced pleuripotent stem cells (iPSs), mesenchymal stem cells (MSCs), and human lung stem cells (hLSCs). Intrinsic therapy refers to the delivery of small molecules (retinoid compounds have been the most studied) that can stimulate the endogenous lung stem/progenitor cells to regenerate and replace damaged structures (See Sun et al review paper below). As mentioned above, human trials to date have largely failed in showing any benefit but there remain questions about appropriate candidates for such therapy, type of therapy, timing of therapy, dosing issues and a host of other variables that require further study. One of the salient questions is whether these therapies need to be started earlier in less severe stages of the disease process. Of course, if that is found to be the case then a major issue will be whether early identification, smoking cessation, adherence to conventional treatments and addressing comorbid conditions may be as or more effective. The papers presented in this Journal Club include an excellent, comprehensive state of the art review of the studies to date and the important future lines of research. The other recent papers address some of the questions raised in the review article. Note: Abstracts are presented in their original, published format and have not been edited to match JCOPDF style.

Sputum plug selection under inverted microscopy improves microbial identification during exacerbations of airway diseases.

Salivary contamination decreases the yield of identifying potential airway bacterial and fungal pathogens in routine cultures of spontaneous or induced sputum during exacerbations of airway diseases. We investigated the utility of selecting out the squamous cells from sputum using inverted microscopy. Sputum was obtained from fifty subjects, then divided to facilitate parallel processing of paired samples for gram-stain and semi-quantitative cultures, and quantitative cytometry. Selective processing under inverted microscopy allowed for fewer sample rejections (2% vs. 24%) and greater culture positivity (58% vs. 24%) compared with routine practices, with significant yield of fungal organisms. While known pathogens were associated with intense sputum neutrophilia, organisms that were not routinely considered as airway pathogens were also associated with modest neutrophilia indicating that they are capable of inducing a clinically relevant cellular response. Sputum selection under inverted microscopy improves the detection of bacterial pathogens during infective exacerbations. The methods to assign pathogenicity to microbes in the airway needs to be re-visited by assessing the cellular responses that they evoke in the airways.

Protease-activated receptor 2 activates airway apical membrane chloride permeability and increases ciliary beating.

Mucociliary clearance, driven by the engine of ciliary beating, is the primary physical airway defense against inhaled pathogens and irritants. A better understanding of the regulation of ciliary beating and mucociliary transport is necessary for identifying new receptor targets to stimulate improved clearance in airway diseases, such as cystic fibrosis and chronic rhinosinusitis. In this study, we examined the protease-activated receptor (PAR)-2, a GPCR previously shown to regulate airway cell cytokine and mucus secretion, and transepithelial Cl- current. PAR-2 is activated by proteases secreted by airway neutrophils and pathogens. We cultured various airway cell lines, primary human and mouse sinonasal cells, and human bronchial cells at air-liquid interface and examined them using molecular biology, biochemistry, and live-cell imaging. We found that PAR-2 is expressed basolaterally, where it stimulates both intracellular Ca2+ release and Ca2+ influx, which activates low-level nitric oxide production, increases apical membrane Cl- permeability ∼3-5-fold, and increases ciliary beating ∼20-50%. No molecular or functional evidence of PAR-4 was observed. These data suggest a novel and previously overlooked role of PAR-2 in airway physiology, adding to our understanding of the role of this receptor in airway Ca2+ signaling and innate immunity.-McMahon, D. B., Workman, A. D., Kohanski, M. A., Carey, R. M., Freund, J. R., Hariri, B. M., Chen, B., Doghramji, L. J., Adappa, N. D., Palmer, J. N., Kennedy, D. W., Lee, R. J. Protease-activated receptor 2 activates airway apical membrane chloride permeability and increases ciliary beating.

Relative susceptibility of airway organisms to antimicrobial effects of nitric oxide.

Nitric oxide (NO) is released in the airway as a critical component of innate immune defense against invading pathogenic organisms. It is well documented that bacteriostatic and bactericidal effects of NO are concentration-dependent. However, few data exist comparing relative susceptibility of common pathogens to NO at physiologic concentrations. In this study we evaluated the effects of NO on 4 common airway bacteria and 1 fungus, and examined the potential implications of discrepancies in sensitivity. Staphylococcus epidermis, Staphylococcus aureus, Klebsiella pneumoniae, Pseudomonas aeruginosa, and Candida albicans cultures were adjusted to a uniform optical density (OD) and grown in log phase at 37°C with varying concentrations of NO formed by DETA NONOate. Both OD readings and colony forming units (CFUs) were measured at varying time-points to evaluate for inhibitory effects of NO. P aeruginosa and C albicans were significantly more sensitive to NO at physiologic concentrations typical of the human airway. S aureus was attenuated by NO to a lesser degree, and K pneumoniae and S epidermis were more resistant to NO at all concentrations tested. Air surface liquid from cultured human sinonasal epithelial cells had an additive effect in bacterial killing of P aeruginosa, but not in S aureus. Common airway pathogens have varying levels of susceptibility to NO at physiologic concentrations of innate immune defense. Relative sensitivity of P aeruginosa and relative resistance of S epidermis may help explain the composition of the healthy microbiome, as well as opportunistic infection in the absence of induced NO release.

A prospective, observational cohort study of the seasonal dynamics of airway pathogens in the aetiology of exacerbations in COPD

BackgroundThe aetiology of acute exacerbations of COPD (AECOPD) is incompletely understood. Understanding the relationship between chronic bacterial airway infection and viral exposure may explain the incidence and seasonality of these...

Preoperatiove Airway Bacterial Colonization: the Missing Link between Non-small Cell Lung Cancer Following Lobectomy and Postoperative Pneumonia?

背景与目的外科手术是目前治疗肺癌的主要手段，肺癌患者围术期死亡的主要原因仍是术后肺炎。已有的研究结果显示致病性气道定植菌被认为是术后肺部并发症的一个独立危险因素，本研究旨在探讨术前致病性气道定植菌的存在与术后发生肺炎的关系及其危险因素。方法横断面调查2014年5月至2015年1月连续收治于成都市6家三级甲等医院胸外科行手术治疗的125例非小细胞肺癌患者，术前经纤维支气管镜取气管及支气管内液细菌学标本，并检测术前血清肺表面活性蛋白D（surfactant protein D, SP-D）水平，术后肺部相关并发症进行分析。结果肺癌患者术前合并致病性气道定植菌的发生率为15.2%（19/125），以革兰氏阴性菌为主（19/22, 86.36%）；肺癌患者术前合并致病性气道定植菌的高危因素为：高龄（≥75岁）和长期吸烟史（吸烟指数≥400支/年）；术后肺部相关并发症和术后肺炎发生率在肺癌合并致病性气道定植菌组（42.11%, 26.32%）均显著高于非合并组（16.04%, 6.60%）（P=0.021, P=0.019）。术前血清SP-D浓度在肺癌合并致病性气道定植菌（31.25±6.09）显著高于非合并组（28.17±5.23）（P=0.023）。并发术后肺炎患者中气道致病性定值菌发生率为41.67%（5/12），其发生率是无手术后肺炎患者的3.4倍（OR=3.363, 95%CI: 1.467-7.711）。结论肺癌患者合并致病性气道定植菌与术后肺炎发生密切相关，且高危险因素是高龄和长期吸烟史。

(624) - Characteristics of Perioperative Airway Pathogens in Living and Cadaveric Lung Transplantation

(624) - Characteristics of Perioperative Airway Pathogens in Living and Cadaveric Lung Transplantation

Reemergence of Lower-Airway Microbiota in Lung Transplant Patients with Cystic Fibrosis.

Chronic lung infections are a hallmark of cystic fibrosis; they are responsible for progressive airway destruction and ultimately lead to respiratory death or the requirement for life-saving bilateral lung transplant. Furthermore, recurrent isolation of airway pathogens such as Pseudomonas aeruginosa in the allograft after transplant is associated with adverse outcomes, including bronchiolitis obliterans syndrome and acute infections. Little information exists on the impact of bilateral lung transplant on the lower-airway microbiota. To compare, at a microbiome and single-pathogen level (P. aeruginosa), the bacterial communities in pre- and post-transplant samples. We retrospectively accessed our biobank of sputum samples and sputum-derived bacterial pathogens for patients who had matched samples, including those who were clinically stable before transplant, those who had a pulmonary exacerbation before transplant, and those who had pulmonary exacerbation after transplant. We used 16S ribosomal RNA gene sequencing to characterize the lower-airway microbiome of 14 adult transplant patients with cystic fibrosis. Genotyping and phenotyping of P. aeruginosa isolates from 12 of these patients with matched isolates was performed. Although α-diversity (richness and evenness) of patient microbiomes was similar before and after transplant, β- diversity (core microbiome composition) measures stratified patients evenly into two groups with more similar and more dissimilar communities. P. aeruginosa strains isolated before transplant were found to reemerge in 11 of 12 patients; however, phenotypic variation was observed. These findings indicate that recolonization by P. aeruginosa after transplant is almost always strain specific, suggesting a within-host source. The polymicrobial colonization of the airways after transplant does not always reflect the pretransplant sputum microbiota.

The microbiome of the maxillary sinus and middle nasal meatus in chronic rhinosinusitis

This multicenter study was focused on the identification of the microorganisms inhabiting the maxillary sinus and middle nasal meatus in chronic rhinosinusitis. 112 middle meatus swabs and 112 maxillary sinus aspirates from 103 patients were available for culture. A total of 244 strains of microorganisms representing more than 50 families were identified in the maxillary sinus and middle nasal meatus (164 and 80, respectively). These included 154 (63.0%) strains of aerobic bacteria from 32 species and 90 (37.0%) strains of anaerobic bacteria from 23 species. Aerobes were more common than anaerobes in both the nasal cavity (78.7% vs. 21.3%) and in the maxillary sinus (55.2% vs. 44.8%). Species of Streptococci (28.8%) and Prevotella (17.8%) were the most common findings in the maxillary sinus aspirates. S. pneumonia, H. influenza, and S. aureus were relatively rare, and found in only 6.7%, 5.4%, and 8.9% of the samples, respectively. The results obtained suggest that common upper airway pathogens do not play a major role in the pathogenesis of chronic rhinosinusitis. The microbiome of inflamed sinonasal mucosa is extremely diverse and involves exotic species of bacteria that, to date, have not been considered as potential inhabitants of the paranasal sinuses.

Induced sputum to detect lung pathogens in young children with cystic fibrosis.

Induced sputum sampling holds promise as a method for obtaining samples representative of the lower airways in young children. Collection of induced sputum samples in young children differs from older children and adults' as pharyngeal suctioning is often required. Our aim was to determine the sensitivity and specificity of induced sputum with and without airway clearance techniques to detect lower airway pathogens in children less than age 7 with cystic fibrosis. Microbiological culture results were compared between 61 paired induced sputum and bronchoalveolar lavage fluid samples from young children with cystic fibrosis. The first cohort received no airway clearance and the second cohort received airway clearance. Induced sputum was sampled within 7 days of bronchoscopy. Median age (range) of participants was 3.3 years (0.9-6.7). Sensitivity and specificity (95%CI) of induced sputum was 36.8% (16.3, 61.6), and 69% (52.9, 82.4), respectively (N = 61). In subgroup analysis, induced sputum with (N = 31) and without airway clearance (N = 30) demonstrated sensitivity of 50% (15.7, 84.3) and 27.3% (6.0, 61.0), respectively, and specificity of 60.9% (38.5, 80.3), and 78.9% (54.4, 93.9), respectively. Induced sputum is not highly sensitive or specific as routine surveillance for detection of lower airway pathogens in young children with cystic fibrosis. Pediatr Pulmonol. 2017;52:182-189. © 2016 Wiley Periodicals, Inc.

Performance evaluation of a rapid molecular diagnostic, MultiCode based, sample-to-answer assay for the simultaneous detection of Influenza A, B and respiratory syncytial viruses

BackgroundClinical signs and symptoms of different airway pathogens are generally indistinguishable, making laboratory tests essential for clinical decisions regarding isolation and antiviral therapy. Immunochromatographic tests (ICT) and direct immunofluorescence assays (DFA) have lower sensitivities and specificities than molecular assays, but have the advantage of quick turnaround times and ease-of-use. ObjectiveTo evaluate the performance of a rapid molecular assay, ARIES FluA/B & RSV, using laboratory developed RT-PCR assays (LDA), ICT (BinaxNOW) and DFA. MethodsAnalytical and clinical performance were evaluated in a retrospective study arm (stored respiratory samples obtained between 2006–2015) and a prospective study arm (unselected fresh clinical samples obtained between December 2015 and March 2016 tested in parallel with LDAs). ResultsGenotype inclusivity and analytical specificity was 100%. However, ARIES was 0.5 log, 1–2logs and 2.5logs less sensitive for fluA, RSV and fluB respectively, compared to LDA. In total, 447 clinical samples were included, of which 15.4% tested positive for fluA, 9.2% for fluB and 26.0% for RSV, in both LDA and ARIES. ARIES clinical sensitivity compared to LDA was 98.6% (fluA), 93.3% (fluB) and 95.1% (RSV). Clinical specificity was 100% for all targets. ARIES detected 10.6% (4 fluA, 8 fluB, 11 RSV) and 26.9% (7 fluA, 3 fluB, 22 RSV) more samples compared to DFA and ICT, all confirmed by LDA. ConclusionAlthough analytically ARIES is less sensitive than LDA, the clinical performance of the assay in our tertiary care setting was comparable, and significantly better than that of the established rapid assays.

The Role of Bacterial Secretion Systems in the Virulence of Gram-Negative Airway Pathogens Associated with Cystic Fibrosis.

Cystic fibrosis (CF) is the most common lethal inherited disorder in Caucasians. It is caused by mutation of the CF transmembrane conductance regulator (CFTR) gene. A defect in the CFTR ion channel causes a dramatic change in the composition of the airway surface fluid, leading to a highly viscous mucus layer. In healthy individuals, the majority of bacteria trapped in the mucus layer are removed and destroyed by mucociliary clearance. However, in the lungs of patients with CF, the mucociliary clearance is impaired due to dehydration of the airway surface fluid. As a consequence, patients with CF are highly susceptible to chronic or intermittent pulmonary infections, often causing extensive lung inflammation and damage, accompanied by a decreased life expectancy. This mini review will focus on the different secretion mechanisms used by the major bacterial CF pathogens to release virulence factors, their role in resistance and discusses the potential for therapeutically targeting secretion systems.

A Survival Strategy for Pseudomonas aeruginosa That Uses Exopolysaccharides To Sequester and Store Iron To Stimulate Psl-Dependent Biofilm Formation.

Pseudomonas aeruginosa is an environmental microorganism which is also an opportunistic pathogen that can cause severe infections in immunocompromised individuals. It is the predominant airway pathogen causing morbidity and mortality in individuals affected by the genetic disease cystic fibrosis (CF). Increased airway iron and biofilm formation have been proposed to be the potential factors involved in the persistence of P. aeruginosa in CF patients. Here, we showed that a high level of iron enhanced the production of the key biofilm matrix exopolysaccharide Psl to stimulate Psl-dependent biofilm formation. Our results not only make the link between biofilm formation and iron concentration in CF, but also could guide the administration or use of iron chelators to interfere with biofilm formation in P. aeruginosa in CF patients. Furthermore, our data also imply a survival strategy of P. aeruginosa under high-iron environmental conditions.

The changing prevalence of pulmonary infection in adults with cystic fibrosis: A longitudinal analysis

BackgroundIncreased patient longevity and aggressive antibiotic treatment are thought to impact on the microbial composition of the airways of adults with cystic fibrosis (CF). In this study, we sought to determine if a temporal change in the airway microbiology of adults with CF has occurred over time. MethodsLongitudinal analysis of sputum microbiology results was undertaken on patients attending a large adult CF centre. Clinical status and health outcomes of transitioning patients were also assessed. ResultsA decrease in the prevalence of Pseudomonas aeruginosa, Staphylococcus aureus, Burkholderia cepacia complex and Aspergillus spp. (p=0.001, p<0.001, p=0.002 and p<0.001, respectively) occurred. Improvements in lung function among transitioning patients infected with P. aeruginosa were observed. ConclusionOvertime, a decline in the prevalence of many CF airway pathogens has occurred. Significantly, an incremental improvement in lung function was reported for transitioning patients with current P. aeruginosa infections.

Bacterial sensitivity assessment of multifunctional polymeric coatings for airway stents.

Current interventional technology for pediatric airway obstruction consists of cardiovascular stents and silicon tubes. These devices are composed of permanent materials that have limitations in biocompatibility and mechanical properties that make them controversial for used in pediatrics. Bioresorbable stents offer a temporary intervention that dissolves in the body over time and can serve as a platform for local drug delivery. Here we investigate a novel approach to use an antibiotic, ciprofloxacin, as a polymerization initiator to synthesize poly(ciprofloxacin fumaric acid) (PCFA) and then a second polymer using gadodiamide as an initiator to synthesize poly(gadodiamide ciprofloxacin fumaric acid) (PGCFA). Polymer structure, degradation, thermal properties, and rheological behavior were analyzed. Ciprofloxacin released was determined and polymer degradation extracts were used in bacterial sensitivity assessments with four common airway pathogens. PCFA and PGCFA polymers and drug release properties were compared to our previously published polymer poly(fumaric acid) (PFA). These novel polymers enable new possibilities as coatings for bioresorbable biomedical applications that require antibiotic resistance and imaging capabilities. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 105B: 2153-2161, 2017.

68 Frequency and persistence of CF airway pathogens from diagnosis to age 16 years

68 Frequency and persistence of CF airway pathogens from diagnosis to age 16 years

Susceptibility to Lower Respiratory Infections in Childhood is Associated with Perturbation of the Cytokine Response to Pathogenic Airway Bacteria.

Neonatal colonization of the airways with respiratory pathogens is associated with increased risk of lower respiratory infections (LRI) in early childhood. Therefore, we hypothesized that children developing LRI have an aberrant immune response to pathogenic bacteria in infancy. The objective was to characterize in vitro the early life systemic immune response to pathogenic bacteria and study the possible association with incidence of LRI during the first 3 years of life. The Copenhagen Prospective Studies on Asthma in Childhood2000 (COPSAC2000) is a clinical birth cohort study of 411 children born of mothers with asthma. LRI incidence was prospectively captured from 6-monthly planned visits and visits at acute respiratory episodes. The in vitro systemic immune response to Haemophilus influenzae, Moraxella catarrhalis and Streptococcus pneumoniae was characterized by the production of TNF-α, IFN-γ, IL-2, IL-5, IL-10, IL-13 and IL-17 in peripheral blood mononuclear cells isolated at age 6 months from 291 infants. Data were analyzed by Poisson regression against incidence of LRI in infancy. A multivariable model including all cytokine responses from the 3 different bacterial stimulations significantly identified children at risk of LRI (P = 0.006). The immune response pattern associated with LRI was characterized by perturbed production of several cytokines rather than production of one specific cytokine, and was independent of concurrent asthma. TNF-α and IL-5 were key drivers but did not explain the entire variation in LRI susceptibility. Children at risk of future LRI present a perturbed systemic immune response upon exposure to common airway pathogens in early life.

A Putative ABC Transporter Permease Is Necessary for Resistance to Acidified Nitrite and EDTA in Pseudomonas aeruginosa under Aerobic and Anaerobic Planktonic and Biofilm Conditions.

Pseudomonas aeruginosa (PA) is an important airway pathogen of cystic fibrosis and chronic obstructive disease patients. Multiply drug resistant PA is becoming increasing prevalent and new strategies are needed to combat such insidious organisms. We have previously shown that a mucoid, mucA22 mutant PA is exquisitely sensitive to acidified nitrite (, pH 6.5) at concentrations that are well tolerated in humans. Here, we used a transposon mutagenesis approach to identify PA mutants that are hypersensitive to . Among greater than 10,000 mutants screened, we focused on PA4455, in which the transposon was found to disrupt the production of a putative cytoplasmic membrane-spanning ABC transporter permease. The PA4455 mutant was not only highly sensitive to , but also the membrane perturbing agent, EDTA and the antibiotics doxycycline, tigecycline, colistin, and chloramphenicol, respectively. Treatment of bacteria with plus EDTA, however, had the most dramatic and synergistic effect, with virtually all bacteria killed by 10 mM , and EDTA (1 mM, aerobic, anaerobic). Most importantly, the PA4455 mutant was also sensitive to in biofilms. sensitivity and an anaerobic growth defect was also noted in two mutants (rmlC and wbpM) that are defective in B-band LPS synthesis, potentially indicating a membrane defect in the PA4455 mutant. Finally, this study describes a gene, PA4455, that when mutated, allows for dramatic sensitivity to the potential therapeutic agent, as well as EDTA. Furthermore, the synergy between the two compounds could offer future benefits against antibiotic resistant PA strains.

The microbiome of the maxillary sinus and middle nasal meatus in chronic rhinosinusitis.

This multicenter study was focused on the identification of the microorganisms inhabiting the maxillary sinus and middle nasal meatus in chronic rhinosinusitis. 112 middle meatus swabs and 112 maxillary sinus aspirates from 103 patients were available for culture. A total of 244 strains of microorganisms representing more than 50 families were identified in the maxillary sinus and middle nasal meatus (164 and 80, respectively). These included 154 (63.0%) strains of aerobic bacteria from 32 species and 90 (37.0%) strains of anaerobic bacteria from 23 species. Aerobes were more common than anaerobes in both the nasal cavity (78.7% vs. 21.3%) and in the maxillary sinus (55.2% vs. 44.8%). Species of Streptococci (28.8%) and Prevotella (17.8%) were the most common findings in the maxillary sinus aspirates. S. pneumonia, H. influenza, and S. aureus were relatively rare, and found in only 6.7%, 5.4%, and 8.9% of the samples, respectively. The results obtained suggest that common upper airway pathogens do not play a major role in the pathogenesis of chronic rhinosinusitis. The microbiome of inflamed sinonasal mucosa is extremely diverse and involves exotic species of bacteria that, to date, have not been considered as potential inhabitants of the paranasal sinuses.