xRead - Nasal Obstruction (September 2024) Full Articles

20426984, 2021, 3, Downloaded from https://onlinelibrary.wiley.com/doi/10.1002/alr.22741 by Stanford University, Wiley Online Library on [01/07/2024]. See the Terms and Conditions (https://onlinelibrary.wiley.com/terms-and-conditions) on Wiley Online Library for rules of use; OA articles are governed by the applicable Creative Commons License

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International consensus statement on rhinosinusitis

S. aureus abundance. 740 However, other reports have not reproduced these findings. 741 In 2 prospective studies of antibiotics administered for AECRS, Merkley et al. and Liu et al. observed conflicting effects on bacterial diver sity, where 1 study found increased diversity and the other study found decreased diversity after therapy. 767,768 Further work using novel study designs will be required to understand short-term, long-term, and individualized effects of antibiotics on the sinonasal microbiome. Surgery . Kim et al. performed a prospective, random ized, single-blinded trial to evaluate the effects of bal loon sinus dilation vs large antrostomy on maxillary sinus microbiota and inflammation. 769 The authors found no difference between bacterial burden, cytokine pro files, or endoscopy score between the 2 treatments. How ever, significant differences in relative postoperative abun dance of Staphylococcus , Lactococcus , and Cyanobacte ria , were noted between sides suggesting that the local anatomic environment may influence surface microbial colonization. Jain et al. studied 23 patients undergoing ESS and observed unpredictable shifts in community composi tion with high inter-subject variability, but a general association with increased richness. 770 These findings were echoed in a study of 12 patients undergoing ESS and postoperative antibiotic therapy by Hauser and col leagues, who additionally reported a high degree of resilience suggesting that some patients’ microbiota may not change much in the long-term despite a rather dras tic intervention. 771 In contrast, Cleland and colleagues observed decreased richness after sinus surgery in a cohort of 23 CRS patients. 772 Preliminary work suggests that spe cific microbiota and ecological changes after surgical inter vention may be associated with improved outcomes 741 The importance of these associations is unclear at this time, and will certainly be the focus of continued study. Probiotics . Prebiotic or probiotic administration has received interest in various fields as an alternative method to antibiotics for direction of the microbiome away from pathogen colonization and toward restoration of healthy commensals. Preclinical study suggests potential value of probiotic manipulation for CRS through direct immune modulation of PBMCs, 773 and by antagonism of coloniza tion by the sinus pathogen, S.aureus. 774 Clinical studies at this time are nascent, and are addressed in Section IX.D.8. In conclusion, although CRS microbiome studies are in their early stages, overall composition and diversity distur bances have been observed in several studies. It is worth noting that some of the initial study findings have not been replicated, due to small cohorts and different exper imental methods. The results in the literature are varied and challenging to interpret in aggregate. While impli cated taxa may be present in health and CRS, no consistent

in addition to tissue immune cell profiling, to correlate sev eral bacterial taxa in CRS subjects with dyregulation of var ious host proteins. 751 Although CRS appears to be associated with shifts in microbiota and loss of diversity, it is unclear whether there is a causal relationship of the microbiome in disease or if alterations are a by-product of disease pathophysiology and/or frequently applied therapies. Given the inherent confounders of CRS disease processes and prior therapies, causality and mechanistic understanding for the micro biome in CRS has been challenging to ascertain. Whether there is a direct effect of the microbes, a dysfunctional host reaction to microbes, both, or neither (ie, bystander effect) has been the subject of ongoing debate. In addition to the bacterial dysbiosis that may be present in CRS, a dysfunc tional host reaction to microbiota may also be present. For example, Aurora et al. found minimal differences between the bacterial and fungal microbiomes of CRS vs healthy subjects, but when peripheral leukocytes were exposed to different microbiota, CRS patients produced significantly more IL-5. 752 Such data suggest that a dysfunctional and hyperresponsive host immunologic reaction is at least as important as any underlying microbial difference between CRS and healthy states. In addition to bacterial alterations seen in the micro biome in CRS, viral and fungal changes may also be seen. 753–759 Further in vivo studies of the relationship of viruses and fungi to the sinus microbiome in health, CRS, or AECRS are an area of ongoing interest and will likely evolve with the application of new technologies. Cross-sectional and case-control study designs have been used to associate microbiota with CRS disease sever ity or histopathology. 736,760 Intervention study design and associations with outcomes have also been attempted as another way to support the microbiome’s role in human disease. Nasal irrigations and intranasal corticosteroids . It is plausible that some degree of observed alterations in local microbiota in CRS studies could result from repeated and prolonged medical therapies. 738,761 Topical INCS formula tions may have some inherent antimicrobial activity, 596,762 or their resultant local immune modulation may shift nasal microbiota, with effects that persist even beyond the dura tion of treatment. 763 Similarly, nasal saline irrigation may confer some antimicrobial effect, 764 although literature results associating topical saline use with local microbiome alterations are limited by study design. Antibiotics . Antibiotic administration results in variable and potentially dramatic alterations in mucosal bacterial communities, although existing supporting evidence in the paranasal sinuses is limited. 765,766 In a cross-sectional study by Feazel et al., recent antibiotic use correlated with significant reductions in bacterial diversity and increased