Medical therapy reduces microbiota diversity and evenness in surgically recalcitrant chronic rhinosinusitis

Dead or alive: Deoxyribonuclease I sensitive bacteria and implications for the sinus microbiome

BACKGROUND

Recently, there has been tremendous interest in the sinus microbiome and how it relates to disease. However, a lack of a standardized sample collection and DNA extraction methods makes comparison of results across studies nearly impossible. Furthermore, current techniques fail to identify which components of the microbiome are actually alive within the host at the time of sampling.

OBJECTIVE

To develop and optimize a method to differentiate which bacterial species in the human sinus microbiome are live versus dead.

METHODS

Duplicate samples from the middle meatus of patients with healthy sinus tissue and those patients with chronic rhinosinusitis were collected by using brushes (n = 12), swabs (n = 27), and tissue biopsy (n = 8) methods. One sample from each pair was either deoxyribonuclease I- or control-treated before DNA extraction. The relative bacterial versus human composition of each sample was determined. A 16S ribosomal RNA gene analysis was performed on a six-paired sample from patients with healthy sinus tissue.

RESULTS

We found that swabs and brushes collected a higher percentage of bacterial DNA than did tissue biopsy. We also determined that as much as 50% of the bacteria collected in these samples was already dead at the time of collection. The 16S ribosomal RNA gene analysis found significant changes in the relative abundance of taxa identified in the live versus dead bacterial communities of healthy human sinuses.

CONCLUSIONS

Our findings indicated that swabs provided the best quality microbiome samples and that a large portion of the bacteria identified in the sinus were deoxyribonuclease I sensitive. These results highlighted the need for improved techniques such as those presented here, which can differentiate between living and dead bacteria in a sample, a potentially critical distinction when examining changes in sinus innate immune function because both components play important, but distinct, functions. Further studies will determine how these living and dead bacterial populations shift in different disease states and after clinical intervention.

The role of antibiotics in endoscopic sinus surgery

PURPOSE OF REVIEW

To review and discuss recent literature regarding the use of antibiotics in relation to endoscopic sinus surgery (ESS), including perioperative antibiotics, postoperative antibiotics, and antibiotic usage in the setting of postoperative packing.

RECENT FINDINGS

Perioperative antibiotics are not recommended by the American Society of Health-System Pharmacists. The necessity of antibiotics following ESS is a heavily debated topic. Most studies show little to no improvement in outcomes. Significant improvement in quality-of-life outcomes and endoscopic scoring appears limited to the early postoperative period using conventional postoperative antibiotics. Prolonged macrolide therapy may improve long-term outcomes. There is no convincing evidence to show the need for antibiotics in the setting of postoperative packing.

SUMMARY

The available evidence regarding antibiotic use in relation to ESS overall fails to demonstrate routine benefit; however, the studies have various limitations. Overall, future, well designed, large-scale prospective studies would be beneficial to direct appropriate antibiotic use, whether systemic or topical, in relation to ESS.

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.

Paired analysis of the microbiota of surface mucus and whole-tissue specimens in patients with chronic rhinosinusitis

BACKGROUND

The role of bacteria in the pathogenesis of chronic rhinosinusitis (CRS) remains uncertain. Recent evidence suggests that bacteria are able to establish microcolonies within the underlying mucosa. However, to date there has been no systematic comparison of bacterial community composition and diversity in the surface mucosa with that of the underlying tissue.

METHODS

Paired swabs and whole-tissue samples were collected from the middle meatus of 9 patients with CRS undergoing endoscopic sinus surgery. The bacterial composition and diversity of the samples were determined using 16S rRNA gene amplicon pyrosequencing.

RESULTS

The bacterial communities of both swabs and tissues were dominated by known residents of the sinonasal cavity such as Staphylococcus, Corynebacterium, Prevotella, and Peptoniphilus. Although bacterial diversity (richness) did not differ between the 2 groups of samples, there were significant differences in the composition of bacterial communities. Molecular analyses revealed a large amount of interpersonal variation between patients.

CONCLUSION

Swab and tissue samples revealed similar bacterial diversity to each other and to that of other microbiota studies reported in the CRS literature. However, bacterial composition was significantly different between the 2 sample types, even though the tissue biopsies also comprise bacteria from the surface. We speculate that the bacteria on the surface seed the underlying tissue via the damaged epithelium in CRS patients, which over time develops into a distinct bacterial community.

Staphylococcus aureus and the ecology of the nasal microbiome

The human microbiome can play a key role in host susceptibility to pathogens, including in the nasal cavity, a site favored by Staphylococcus aureus. However, what determines our resident nasal microbiota-the host or the environment-and can interactions among nasal bacteria determine S. aureus colonization? Our study of 46 monozygotic and 43 dizygotic twin pairs revealed that nasal microbiota is an environmentally derived trait, but the host's sex and genetics significantly influence nasal bacterial density. Although specific taxa, including lactic acid bacteria, can determine S. aureus colonization, their negative interactions depend on thresholds of absolute abundance. These findings demonstrate that nasal microbiota is not fixed by host genetics and opens the possibility that nasal microbiota may be manipulated to prevent or eliminate S. aureus colonization.

Sinonasal microbiome sampling: a comparison of techniques

Background

The role of the sino-nasal microbiome in CRS remains unclear. We hypothesized that the bacteria within mucosal-associated biofilms may be different from the more superficial-lying, free-floating bacteria in the sinuses and that this may impact on the microbiome results obtained. This study investigates whether there is a significant difference in the microbiota of a sinonasal mucosal tissue sample versus a swab sample.

Methods

Cross-sectional study with paired design. Mucosal biopsy and swab samples were obtained intra-operatively from the ethmoid sinuses of 6 patients with CRS. Extracted DNA was sequenced on a Roche-454 sequencer using 16S-rRNA gene targeted primers. Data were analyzed using QIIME 1.8 software package.

Results

At a maximum subsampling depth of 1,100 reads, the mean observed species richness was 33.3 species (30.6 for swab, versus 36 for mucosa; p > 0.05). There was no significant difference in phylogenetic and non-phylogenetic alpha diversity metrics (Faith’s PD_Whole_Tree and Shannon’s index) between the two sampling methods (p > 0.05). The type of sample also had no significant effect on phylogenetic and non-phylogenetic beta diversity metrics (Unifrac and Bray-Curtis; p > 0.05).

Conclusion

We observed no significant difference between the microbiota of mucosal tissue and swab samples. This suggests that less invasive swab samples are representative of the sinonasal mucosa microbiome and can be used for future sinonasal microbiome studies.

Magnetic nanoparticles: a new tool for antibiotic delivery to sinonasal tissues. Results of preliminary studies

Herein we examined the toxicity, penetration properties and ability of Fe2O3·nH2O magnetic nanoparticles extracted from silt of the Borovoye Lake (Krasnoyarsk, Russia) to bind an antibiotic. Experimental studies were carried out using magnetic nanoparticles alone and after antibiotic exposure in tissue samples from nasal mucosa, cartilage and bone (in vitro). Toxicity of particles was studied in laboratory animals (in vivo). Tissues removed at endonasal surgery (nasal mucosa, cartilage and bone of the nasal septum) were placed in solution containing nanoparticles and exposed to a magnetic field. Distribution of nanoparticles was determined by Perls' reaction. After intravenous injection, possible toxic effects of injected nanoparticles on the organs and tissues of rats were evaluated by histological examination. Binding between the nanoparticles and antibiotic (amoxicillin clavulanate) was studied using infrared spectroscopy. In 30 in vitro experiments, magnetisation of Fe2O3·nH2O nanoparticles resulted in their diffuse infiltration into the mucosa, cartilage and bone tissue of the nose and paranasal sinuses. Intravenous injection of 0.2 ml of magnetic nanoparticles into the rat's tail vein did not result in any changes in parenchymatous organs, and the nanoparticles were completely eliminated from the body within 24 hours. The interaction of nanoparticles with amoxicillin clavulanate was demonstrated by infrared spectroscopy. Positive results of experimental studies provide a basis for further clinical investigations of these magnetic nanoparticles and their use in otorhinolaryngology.

The nasal microbiota in health and disease: variation within and between subjects

Chronic rhinosinusitis (CRS) affects approximately 5% of the adult population in Western societies and severely reduces the patient's quality of life. The role of bacteria in the pathogenesis of this condition has not yet been established with certainty. However, recent reports of bacterial and fungal biofilms in CRS highlight a potential role for these microorganisms. In this study, 16S rRNA gene-targeted amplicon pyrosequencing and qPCR were used to determine the composition and abundance, respectively, of the sinus microbiota within 9 patients with CRS and 6 healthy individuals. Within-patient variability was also investigated by sampling from anterior nares, inferior turbinate, and middle meatus on each side of the sinuses. Our results indicate that more of the variation in bacterial composition can be explained by inter-personal differences, rather than sampling location or even disease status. In addition, bacterial community diversity was significantly lower in CRS samples compared to those from healthy subjects, whereas bacterial load was not associated with disease status. Although members of the genera Corynebacterium and Staphylococcus were prevalent in the majority of samples (including healthy subjects), the large amount of variation observed between individuals, particularly within the CRS cohort, suggests that an imbalance or dysbiosis in community structure could be the driving force behind the disease. Ultimately, understanding the causes of variation within the sinus microbiota may lead to more personalized treatment options for CRS.

The microbiome of the upper airways: focus on chronic rhinosinusitis

Upper airway diseases including allergic rhinitis, chronic rhinosinusitis with or without polyps, and cystic fibrosis are characterized by substantially different inflammatory profiles. Traditionally, studies on the association of specific bacterial patterns with inflammatory profiles of diseases had been dependent on bacterial culturing. In the past 30 years, molecular biology methods have allowed bacterial culture free studies of microbial communities, revealing microbiota much more diverse than previously recognized including those found in the upper airway. At presence, the study of the pathophysiology of upper airway diseases is necessary to establish the relationship between the microbiome and inflammatory patterns to find their clinical reflections and also their possible causal relationships. Such investigations may elucidate the path to therapeutic approaches in correcting an imbalanced microbiome. In the review we summarized techniques used and the current knowledge on the microbiome of upper airway diseases, the limitations and pitfalls, and identified areas of interest for further research.

Impact of saline irrigation and topical corticosteroids on the postsurgical sinonasal microbiota

BACKGROUND

Topical treatments with nasal saline irrigation, topical steroid sprays, or corticosteroid rinses can improve sinonasal symptoms in chronic rhinosinusitis (CRS). However, the impact of these therapies on commensals (Corynebacterium) and on biofilm pathogens associated with CRS (Staphylococcus aureus and Pseudomonas) is not well characterized.

METHODS

Paired nasal and sinus swabs were collected endoscopically from 28 controls and 14 CRS patients with nasal polyposis (CRSwNP) who had not received systemic antibiotics or corticosteroids in the previous 8 weeks. Total DNA from swab eluents were extracted and analyzed by 16S rRNA gene-based pyrosequencing. A total of 359,077 reads were obtained and classified taxonomically. The association of use of topical therapies with sinonasal microbiota composition was assessed by factor/vector-fitting. The proportional abundances of sinonasal bacteria between topical therapy users and nonusers were further compared by 2-tailed Kolmogorov-Smirnov test among controls and among CRSwNP participants.

RESULTS

Nasal saline irrigation, with or without added budesonide, was not associated with significantly distinct sinonasal microbiota composition or significantly decreased Pseudomonas or S. aureus abundances among either controls or CRSwNP participants. Corynebacterium was slightly lower in controls that reported using saline irrigation than those who did not. No significant association was found between nasal saline irrigation and the proportional abundances of Pseudomonas, S. aureus, and Corynebacterium in CRSwNP participants. However, male CRSwNP patients were noted to have significantly higher Corynebacterium proportional abundances than their female counterparts. The use of topical steroid sprays was associated with a distinct microbiota in control subjects, characterized by higher proportional abundances of Dolosigranulum and Simonsiella and a lower proportional abundance of Campylobacter.

CONCLUSION

Nasal saline irrigation is not associated with a distinct alteration in the proportional abundance of commensal bacteria or biofilm-forming pathogens in CRSwNP patients. However, use of topical intranasal corticosteroid sprays in control subjects is associated with a distinct sinonasal microbiota.

Therapeutic ultrasound as a treatment modality for chronic rhinosinusitis

Chronic rhinosinusitis (CRS) is a chronic infective, inflammatory upper respiratory disease. While the current medical treatment of CRS focuses on the systemic and topical use of steroids and/or antibiotics, many bacteria residing on mucosal surfaces of patients with CRS exist in a biofilm state, making them resistant to most systemic antibiotics. Alternative therapeutic strategies that include blocking bacterial molecular communication, inhibiting biofilm matrix production and breaking down bacterial biofilms are all being explored. Physical therapies such as therapeutic ultrasound (US) have been advocated and utilized as a treatment modality for CRS for many years. US may have antiinflammatory actions and can also be used for the local delivery of drugs through the skin. Therapeutic US, which has been shown in clinical studies to be an effective treatment for both acute rhinosinusitis and CRS, offers significant potential in CRS management.

The role of the human microbiome in otolaryngology-head and neck surgery: a contemporary review

OBJECTIVES/HYPOTHESIS

The human microbiome represents the collective genomes and gene products of microbes living within and on humans. The objective of this review is to provide a summary of the current microbiome literature pertaining to otolaryngology-head and neck surgery.

DATA SOURCE

Ovid MEDLINE.

METHODS

Scientific publications with clinical correlates.

RESULTS

Human microbiome studies have been facilitated by culture-independent, high-throughput sequencing methods. Data from the Human Microbiome Project has shown that the composition of the human microbiome is specific to each body site and that each individual has a unique microbiome. Alterations in the human microbiome are associated with some disease states; thus, novel therapeutic strategies are being developed based on concepts and findings stemming from microbiome research.

CONCLUSIONS

Although a growing body of research shows potential significance of the human microbiome for human health and disease, there is a paucity of microbiome studies in otolaryngology. More studies are required to increase our understanding of the indigenous microbiota and their effects on diseases of the head and neck.