Comparison of the human microbiome in adults and children with chronic rhinosinusitis.

We hypothesized that differences in the microbiome could be a cause of the substantial differences in the symptoms of and treatment options for adult and pediatric patients with chronic rhinosinusitis (CRS). First, we characterized the differences in the nasal microbiomes of pediatric and adult CRS patients. Swabs were obtained from 19 patients with chronic rhinosinusitis (9 children and 10 adults). The bacterial 16S rRNA gene was pyrosequenced to compare the microbiota of the middle meatus. No significant differences were found in species richness and alpha-diversity indices between the two groups. However, in the comparison of diversity between groups using the unweighted pair group method with arithmetic mean (UPGMA) clustering of microbiome taxonomic profiles, we observed a relatively clear separation between the adult and pediatric groups. Actinobacteria had a significantly higher relative abundance in the adult group than in the pediatric group at the phylum level. At the genus level, Corynebacterium showed significantly higher relative abundance in the adult group than in the pediatric group. This is a comparative study between the microbiomes of adult and pediatric CRS patients. We expect this study to be the first step in understanding the pathogenesis of CRS in adults and children using microbiome analysis.

Introduction

Chronic rhinosinusitis (CRS) is a chronic inflammation of the nasal and paranasal sinuses, persists for more than 12 weeks, and is accompanied by symptoms such as nasal obstruction, congestion, discharge, cough, and loss of smell [1]. The prevalence of adult CRS in the Korean population was 8.4% in a study analyzing 5-year cross-sectional data from the Korean National Health and Nutrition Examination Survey [2]. Results from the National Health Interview Survey of the United States (US) also reported similar results (12.5% of the US population) [3]. Due to the high prevalence and close connection between its symptoms and daily life, CRS accounts for substantial health care expenditures in terms of office visits, antibiotic prescriptions filled, lost work days, and missed school days. Treatment strategies for CRS patients are limited due to their heterogeneous pathology. Disturbance of the nasal microbiome is proposed as a new strategy to overcome CRS [4].

The microbiota, the microorganisms that live inside and on humans, contain nearly ten times more cells than human somatic and germ cells combined. Recently, newly developed tools, such as high-throughput sequencing, have allowed us to begin to appreciate the role of the microbiota by investigating the members of a microbial community [5, 6]. Now, we understand that dysfunctions of the human microbiota are linked to various diseases, and the potential of the human microbiome as an early detection biomarker and target for therapeutic intervention is a vibrant area of current research [7]. The microbiome is also attracting attention with regard to its role in the development or progression of disease in the study of CRS pathogenesis [8].

Pediatric CRS differs significantly from adult CRS in terms of clinical features [9]. The symptoms of pediatric CRS differ from those of the adult CRS. According to the 2012 European position paper on rhinosinusitis and nasal polyps (EPOS) guidelines, persistent cough is an important symptom of CRS in children. In addition, unlike that in the adult CRS group, the mainstay of therapy in the pediatric CRS group is medical treatment and surgery is reserved for a relatively small number of patients who do not respond to medical treatment [10]. It is generally believed that the difference is due to anatomy, histopathology, state of the immune system, and effect of certain predisposing factors/comorbidities, such as frequent viral upper respiratory tract infections, and enlarged adenoidal pads [11, 12]. We hypothesized that differences in the microbiome could be a cause of the substantial differences between the adult and pediatric populations. In particular, we assumed that the nasal microbiome differed between the pediatric and adult patients with CRS. Therefore, in the present study, we investigated the bacterial abundance and diversity in children and adults with CRS and evaluated the differences between the two groups.

Materials and methods

Sample collection

Intraoperative swabs were obtained from 19 patients (9 children and 10 adults) and taken after general anesthesia, from the middle meatus and/or anterior ethmoid region in all patients. Samples were collected carefully to avoid contamination from the anterior nostril, nasal vestibule and nasal cavity. During swabbing, we used nasal speculum and endoscope and did not touch the anterior nostril and nasal vestibule. Samples were immediately placed on ice and frozen at − -80°C. The diagnosis of CRS was based on historical, endoscopic, and radiographic criteria and CT findings of sinuses according to the 2012 European position paper on rhinosinusitis and nasal polyps (EPOS) guidelines. The symptoms of rhinosinusitis in adults included nasal obstruction and discharge (ant. or post.), facial pain/pressure, and reduction of sense of smell. However, the symptoms of rhinosinusitis in children included nasal obstruction and discharge (ant. or post.), facial pain/pressure, and cough. CRS diagnosis was confirmed when the above-mentioned symptoms lasted for more than three months. None of the patients had taken oral steroids, non-steroidal anti-inflammatory drugs, antihistamines, or antibiotics for at least four weeks. Patients who smoked were excluded. Patients with pregnancy, immunocompromised, trauma, previous head and neck radiation, and other sinonasal diseases, such as acute rhinosinusitis, fungal sinusitis, and tumors were excluded. Pediatric patients with primary ciliary dyskinesia or cystic fibrosis were also excluded from the study. All patients were recruited from the Department of Otorhinolaryngology, Hallym University Dongtan Sacred Heart Hospital, Korea. Informed consent was obtained according to the Declaration of Helsinki. This study was approved by the Hallym University Institutional Review Board, which also authorized the research, and was carried out in accordance with the guidelines of the Human Ethics Committee of Hallym University Dongtan Sacred Heart Hospital. (2016-524-I)

DNA extraction and pyrosequencing of the 16S rRNA gene

DNA was extracted using a DNeasy Blood & Tissue Kit (Qiagen, Hilden, Germany). The entire contents of the swab tube were carefully poured into a 1 mL sterile tube. Total DNA of all collected samples was extracted using enzymatic and mechanical protocols. DNA concentration and purity were measured using a UV-VIS spectrophotometer (Quawell, CA, USA). Extracted DNA was stored at -70°C until sequencing. DNA samples from the pediatric and adult groups were subjected to pyrosequencing. Polymerase chain reaction (PCR) amplification was performed on extracted DNA using primers targeting the V3 to V4 regions of the 16S rRNA gene. For bacterial amplification, primers 341F (5’-TCGTCGGCAGCGTC-AGATGTGTATAAGAGACAG-CCTACGGGNGGCWGCAG-3’) and 805R (5’-GTCTCGTGGGCTCGG-AGATGTGTATAAGAGACAG-GACTACHVGGGTATCTAATCC-3’) were used. Amplifications were carried out under the following conditions: initial denaturation at 95°C for 3 min, followed by 25 cycles of denaturation at 95°C for 30 seconds, primer annealing at 55°C for 30 s, and extension at 72°C for 30 s, with a final elongation at 72°C for 5 min.

Then, a secondary amplification was performed with the i5 forward primer (5’-AATGATACGGCGACCACCGAGATCTACAC-XXXXXXXX-TCGTCGGCAGCGTC-3’; X indicates the barcode region) and i7 reverse primer (5’-CAAGCAGAAGACGGCATACGAGAT-XXXXXXXX-AGTCTCGTGGGCTCGG-3’) to attach the Illumina NexTera barcode. The conditions of the secondary amplification were identical to the former ones, except that the amplification cycle was set to 8. The PCR product was confirmed by 2% agarose gel electrophoresis and visualized under a Gel Doc system (BioRad, Hercules, CA, USA). The amplified products were purified using the QIAquick PCR Purification Kit (Qiagen, Valencia, CA). Equal concentrations of purified products were pooled and short fragments (non-target products) were removed using an Ampure beads kit (Agencourt Bioscience, Beverly, MA). The quality and product size were assessed on a Bioanalyzer 2100 (Agilent, Palo Alto, CA) using a DNA 7500 chip. Mixed amplicons were pooled and sequenced at Chunlab, Inc. (Seoul, Korea) on an Illumina MiSeq Sequencing system (Illumina, San Diego, CA) according to the manufacturer’s instructions.

Pyrosequencing data analysis

Processing raw reads started with a quality check and filtering of low quality (average score < 25) reads by trimmomatic 0.32. After the quality check, paired-end sequence data were merged together using PandaSeq. Primers were then trimmed with ChunLab’s in-house program at a similarity cutoff of 0.8. Sequences were denoised using Mothur’s pre-clustering program, which merges sequences and extracts unique sequences, allowing up to 2 differences between sequences. The Ezbiocloud database (http://www.ezbiocloud) was used for taxonomic assignment using BLAST 2.2.22 and pairwise alignment, which was used to calculate similarity [13]. Uchime and the non-chimeric 16S rRNA database from Ezbiocloud were used to detect chimeras on reads that contained less than a 97% best hit similarity rate. Sequence data were then clustered using CD-Hit7 and UCLUST8, and an alpha diversity analysis was conducted.

Statistical analysis

Statistical analysis was performed using R version 3.1.2 (http://www.r-project.org/). The Wilcoxon rank-sum test was performed at each level (phylum, genus, and species) to confirm the differences in the microbiomes between the two groups. The Kruskal-Wallis rank sum test and Tukey’s post hoc test were used to analyze the differences in the composition of the microbiome between subgroups. Results with a value of p < 0.05 were considered statistically significant.

Results

Subjects and sequence reads counts

Swabs were obtained from 19 patients (9 children and 10 adults); pediatric patients comprised five males and four females (mean age 9.7 ± 3.7), while adult patients comprised five males and five females (mean age 46 ± 14.6). After the data was prefiltered and passed the quality check, the number of total reads and total valid reads were counted (Table 1). An average of 76,459 bacterial 16S rRNA-encoding gene sequence reads from pediatric CRS patients and an average of 70,606 from adult CRS patients were obtained. Rates of valid reads out of total reads ranged from 71.7% to 99.6% in pediatric patients and from 90.4% to 98.9% in adult patients. The mean sequence length after sequence processing per sample from all patient sinus mucosa ranged from 412 to 427 bases. There was no statistical significance in the number of total reads after pre-filtering and the rates of valid reads out of total reads between the pediatric and adult groups (Fig 1(A)). These findings indicate that both patient groups had similar bacterial loads.

Table 1

Results from sequence read counts.

	Read counts			Read lengths			Taxonomic assignment
Pediatric Patients	Total reads	Valid reads	percentage	Min	Average	Max	No. of reads identified (Species level)		No of species found
HS10	91073	90590	99.5	309	426.8	461	87924		30
HS42	144783	138855	95.9	302	416.6	482	128902		104
HS45	157693	155148	98.4	374	425.4	456	145397		81
HS48	33965	24354	71.7	315	413.2	454	22259		356
HS50	32237	24838	77	380	413.2	450	23191		253
HS51	31378	25629	81.7	335	414.7	449	23996		350
HS57	48254	45967	95.3	372	416.2	451	44655		147
HS37	52303	52089	996	303	426.8	477	50720		105
HS59	96444	95590	99.1	306	425.2	473	92113		121
	Read counts			Read lengths			Taxonomic assignment
Adults patients	Total reads	Valid reads	percentage	Min	Average	Max	No. of reads identified (Species level)	No of species found
HS14	102470	96852	94.5	315	412.8	462	91386	476
HS9	16270	16049	98.6	300	420.5	480	15272	43
HS47	159721	158005	98.9	317	413.7	462	146741	105
HS52	28925	24730	85.5	317	419.9	462	23529	175
HS55	69432	62792	90.4	397	416.6	449	60873	198
HS35	96253	95134	98.8	303	421.1	479	91303	211
HS61	55479	54320	97.9	325	414.1	472	52621	167
HS67	49856	48906	98.1	300	412.1	460	47004	61
HS69	60011	59272	98.8	307	417	482	57941	100
HS71	67643	66430	98.2	352	409.4	452	64360	80

Fig 1

Sequence read counts from middle meatal samples.

(A) Comparison of total valid reads and (B) comparison of number of species found between adult and pediatric CRS patients. There was no statistically significant difference between the two groups in both comparisons.

Taxonomic assignments

Valid reads were assigned against reference databases at the species level. A read was defined as being successfully identified when it matched the reference database at the species level with a 97% similarity cutoff. The number of reads identified at the species level that were obtained per sample ranged from 22,259 to 145,397 in pediatric CRS patients and from 15,272 to 146,741 in adult CRS patients. The taxonomic coverage of a database ranged from 91.4% to 97.3% in the pediatric group and from 92.9% to 97.7% in the adult group. There was no statistical significance in the number of reads identified at the species level and the taxonomic coverage between the pediatric and adult groups.

We directly counted uniquely identified species based on the reference database, and numbers from pediatric CRS patient samples ranged from 30 to 356 (mean 171.9). The number of unique species identified from adult CRS patient samples ranged from 43 to 476 (mean 161.6). There was no statistically significant difference in the number of species found between pediatric and adult groups (Fig 1(B)).

Comparison of richness

Richness is defined as the number of unique species per sample identified using a reference database. The number of operational taxonomic units (OTUs) obtained per sample from pediatric patients in the middle meatal mucosa ranged from to 35–585 (median: 156) and 48–557 (median: 169) in the adult group. There was no statistically significant difference in the number of OTUs between the pediatric and adult groups (p = 0.744). We also checked the Chao-1 species richness indexes in intergroup comparisons, and no significant differences were found (Fig 2(A)). No significant differences were observed in other species richness indices, such as abundance-based coverage estimators (p = 0.683) and Jackknife estimation (p = 0.568) (Fig A in S1 Appendix).

Fig 2

A box plot of the alpha diversity indices in the adult and pediatric CRS groups.

(A) Chao1 richness values, (B) Shannon diversity indices. Overall microbial alpha diversity did not differ significantly between the two groups. (C) UPGMA clustering of microbiome taxonomic profiles in both groups using the UniFrac distance, showing a relative clear separation between the two groups. (D) Principal coordinate analysis (PCoA) plots showed two principal coordinates that explained the clear distance between samples.

Different types of statistical indices are used to describe diversity. Alpha-diversity, referring to intra-community diversity, was measured by the Shannon index, and there was no significant difference between the two groups (Fig 2(B)). Significant differences were also not observed in other alpha-diversity indices such as the NPShannon (p = 0.683), Simpton (p = 0.514), and phylogenetic diversity (p = 0.744) (Fig B in S1 Appendix). Beta diversity showing comparison of diversity between different groups was evaluated by UPGMA clustering of microbiome taxonomic profiles in both groups using the UniFrac distance (Fig 2(C)) and principal coordinate analysis (PCoA) plots (Fig 2(D)). A relatively clear separation was observed between the adult and pediatric groups (Fig 2(C) and 2(D)).

Composition of the CRS microbiome in pediatric and adult patients

We determined the bacterial community composition and examined differences in their relative abundance between adult and pediatric groups (Fig 3). If a species had an average relative abundance under 1%, it was classified as an “etc.” At the phylum level, Firmicutes was most abundant (37.07%) in the pediatric patients, followed by Proteobacteria (33.68%), Bacteroidetes (11.00%) and Actinobacteria (9.38%). In the adult group, Actinobacteria was the most dominant bacteria and had a significantly higher relative abundance (35.96%) than in the pediatric group (p = 0.034). While Firmicutes (27.54%) and Proteobacteria (21.26%) were highly abundant in the pediatric group, the abundance was not significantly higher than that in the adult group (Fig 4). Streptophyta, Fusobacteria and Verrucomicrobia made up the remainder of the communities, composing a small fraction (1–6%) in the pediatric patients. Fusobacteria and Tenericutes comprise a small fraction of adult patients.

Fig 3

Abundance of dominant bacteria in patients with CRS.

(A) Bacterial community composition at the phylum level of the nasal cavity of nine pediatric patients and ten adult patients. (B) Comparison of dominant bacterial abundance between adult and pediatric groups at the phylum level, and (C) the comparison at the genus level.

Fig 4

Bacterial species that discriminate between adult and pediatric CRS patients.

Discriminative species that were different between the two groups were Actinobacteria at the phylum level, Corynebacterium at the genus level. *p < 0.05.

At the genus level, Haemophilus (26.8%), Staphylococcus (12.4%), Bacteroides (9.9%), and Corynebacterium (7.9%) were prevalent in the pediatric group. In the adult group, Corynebacterium was the most abundant (25.1%), followed by Staphylococcus (13.1%). On comparing the two groups, we found that only Corynebacterium showed a significantly higher relative abundance in the adult group than in the pediatric group.

Furthermore, at the species level, Haemophilus influenzae (22.0%) was the most abundant in pediatric patients. Staphylococcus aureus (11.9%), Corynebacterium group (7.6%), Bacteroides vulgatus (7.1%), and Streptococcus pneumoniae (6.8%) were prevalent in the pediatric group. In adults, Corynebacterium spp., such as Corynebacterium accolens and Corynebacterium tuberculostearicum were the most abundant (23.7%), followed by Staphylococcus aureus (8.9%). (Fig C in S1 Appendix).

Discussion

The association between CRS and commensal or pathogenic microbes cultured from the nasal cavity and paranasal sinuses has been investigated for a long time. Bacteriological studies in chronic rhinosinusitis are widely performed using culture techniques in the belief that certain bacteria may be pathogenic and play a role in the pathogenesis of sinusitis [14]. It is known that there can be nearly a 99% chance that the bacteria will not be cultured, and as other causes of chronic sinusitis such as mucociliary clearance, host immune response, and remodeling were highlighted more, interest in bacteriological studies has diminished [15]. Although molecular detection methods allow culture-independent investigation of microbial communities, these techniques require tremendous amounts of time and money. However, the introduction of next-generation sequencing(NGS) has not only solved most of the problems related to the previous molecular detection techniques, but it also has elicited new fields of research, including metagenomics [16, 17].

Currently, many studies that have used new NGS techniques have provided extensive evidence that the microbiome can be used to explain a substantially greater percentage of variance in the relevant phenotypes for a given condition or disease [18]. For example, the abundance of Christensenella within the human gut is negatively correlated with body mass index (BMI) and can induce weight loss when experimentally fed to mice [19]. Fecal microbiota transplant in humans has been associated with improvement in behavior and gastrointestinal symptoms of autism [20]. Although disease causality was not shown, as with the above diseases, an airway microbiome study has been performed and the results were viewed with great interest; chronic obstructive pulmonary disease (COPD) and asthma have been the popular target diseases for these microbiome studies. Many studies have shown associations between the respiratory microbiome and the clinical, physiological, and therapeutic features of asthma [21]. It was also shown that exacerbations of COPD are associated with changes in the respiratory microbiota and airway inflammation [22].

A recent meta-analysis of studies comparing the composition of the bacterial microbiome in adult patients with CRS showed that the most abundant bacteria across all subjects were Staphylococcus, Propionibacterium, Corynebacterium, Streptococcus, and an unclassified lineage of Actinobacteria [23]. Another systemic review of a study of adult patients’ microbiome demonstrated that despite the significant heterogeneity of studies, certain phyla including Actinobacteria, Bacteroides, and Firmicutes were consistently present [24]. Corynebacterium and Staphylococcus were the most abundant genera among all adult CRS patients (29% and 16%, respectively) in a recent study conducted in Australia [8]. Our findings were similar to those found in the literature. In the present study, the three genera that had the highest relative abundance were Corynebacterium, Staphylococcus, and Haemophilus (Table A in S1 Appendix).

The most meaningful finding in our study was that there were some differences between pediatric and adult patients in the composition of the CRS microbiome. Only one study showed that a history of acute sinusitis was associated with a significant depletion of the nasopharyngeal microbiome in the relative abundance of taxa, including Faecalibacterium prausnitzii and Akkermansia spp. and enrichment with Moraxella nonliquefaciens [25]. We found only one microbiome study of pediatric patients with CRS in the literature; Stapleton et al. reported that Moraxella, Haemophilus, and Streptococcus are the most abundant taxa in pediatric patients with CRS [26]. Furthermore, there was no significant difference in the microbial composition or diversity between pediatric patients and control subjects [26]. In a study using a culture method, Streptococcus pneumonia (22 of 40), Haemophilus influenzae (14 of 40), Staphylococcus aureus (2 of 40), Moraxella catarrhalis (1 of 40), and α-hemolytic Streptococcus (1 of 40) were dominant in children with rhinosinusitis [25]. Interestingly, there was some overlap between our results and a previous study using a culture-dependent method. At the species level, our study showed that the relative abundances of Haemophilus influenzae, Staphylococcus epidermidis, Bacteroides vulgatus, Corynebacterium pseudodiphtheriticum, and Streptococcus pneumoniae.

In the present study, we showed that there was no statistical difference in the number of total reads, the number of reads identified at the species level and taxonomic coverage rates, and the number of species between pediatric and adult CRS patient groups. There were also no significant differences in species richness indices and alpha-diversity indexes between the two groups. However, beta diversity allowed researchers to dynamically visualize and compare two groups. In this study, UPGMA clustering of microbiome taxonomic profiles in both groups using the UniFrac distance, showed a relatively clear distinction between the two groups. All distance indices were visualized with principal coordinate analysis (PCoA) plots, which had two principal coordinates that explained the greatest distance between samples (Fig 2(D)).

At the phylum level, Firmicutes and Proteobacteria were the most abundant (>30%) in pediatric patients, and Actinobacteria, Firmicutes, and Proteobacteria were the most dominant bacteria (>20%) in the adult group. Among the dominant bacteria, Actinobacteria had a significantly higher relative abundance in the adult group than in the pediatric group. At the genus level, Haemophilus and Staphylococcus were prevalent (>10%) in the pediatric group, and Corynebacterium and Staphylococcus were dominant in the adult group. Corynebacterium had a significantly higher relative abundance in the adult group than in the pediatric group.

The limitations of our study are as follows: (1) we did not show data on healthy people in this study, (2) the sample sizes for each group were small, (3) we were unable to explain the difference between the group means, and (4) we were unable to interpret and clinically apply the antimicrobial sensitivities observed in this study. Nevertheless, this could be a significant comparative study of microbiomes between adult and pediatric CRS patients.

Conclusions

This is a comparative study between the microbiomes of adult and pediatric CRS patients. In the genus, Haemophilus was the most common CRS microbiome in children, and Corynebacterium was the most common CRS microbiome in adults. Our results show the diversity of the human upper airway microbiome in CRS, and we expect the results of our study to help broaden the understanding of pediatric and adult CRS. Further research is needed to analyze the interactions between the human immune system and microbiota in the upper airways and CRS.

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11 Aug 2020

PONE-D-20-20970

Comparison of the Human Microbiome in Adults and Children with Chronic Rhinosinusitis

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Thank you for your submission on an important topic. Although studies on the sinonasal microbiome in adult patients with CRS are increasing, little work has been published on the microbiome of paediatric CRS.

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Reviewer #1: This manuscript does represent a description of a novel comparison between adult and pediatric CRS that to date has not been presented in the literature. I believe this descriptive study is a useful foundation for exploration of the differences between the two diseases at a metagenomic level. The authors' limitations are clearly stated, namely that the patient numbers are small, and it is difficult to make causative conclusions based on the data presented here. The authors make appropriate conclusions based on the data presented. There are several papers looking at acute URIs and sinusitis in children with relation to baseline microbiome composition and microbiome-based interventions, but there is little in the literature looking specifically at pediatric CRS in otherwise healthy children, so this paper is unique.

It would be additionally useful to include more discussion of what the beta diversity findings mean--ie that children's microbial communities are more similar to each other than they are to adults. This would appeal to a broader audience without as much experience in microbiome research.

There were a few changes I would make within the text:

Abstract:

"The bacterial 16S rRNA gene was pyrosequenced to compare the microbiota of the middle meatal." Would change to read middle meatus

Methods:

How was pediatric CRS defined? It would be useful to establish which symptoms/consensus statement definition was used for pediatric CRS, since these differ slightly compared to the adult European Position paper

Figure 4: Legend mentions S. epidermidis but this is not represented in the figure

Results: Page 11-12, lines 195-197

"While Corynebacterium showed a significantly higher relative abundance in the adult group, there was no difference in the abundance of Haemophilus in the adult group."

This is a little unclear. In comparison to the pediatric group?

Discussion: page 13, lines 226-235

Important to clarify that these studies were done in adult CRS patients

Discussion: page 13, lines 240-241 Similar and very recently published paper

Stapleton AL, Shaffer AD, Morris A, Li K, Fitch A, Methé BA. The microbiome of pediatric patients with chronic rhinosinusitis. InInternational Forum of Allergy & Rhinology 2020 Apr 29.

https://doi.org/10.1002/alr.22597

Throughout the discussion, there are several conclusions about the relative abundance of specific species in the adult and pediatric populations, but this data is not presented or discussed in the results. It would be useful to present this data in the results section since so much of the discussion focuses on these data

Discussion: page 14, lines 265-268

This sentence is split into two with ‘and’ between limitations 2 and 3 and a period before limitation 4. Would combine into one full sentence.

Reviewer #2: The manuscript appears to be technically sound and is well written and logical. The subject is pertinent and important in describing the microbiome in chronic rhinosinusitis (CRS) in adults and children. The methods appear to be well described. On its face, the results appear to be valid.

There are several features that bear revision.

Major Issues:

In the first sentence of the abstract, the authors state "Clinical features of pediatric CRS differ significantly from those of adult CRS", but this is not explained. Further, in the introduction on page 3 line 22, the same assertion is made. The study that is quoted (Silviu-Dan) contains a table of "Symptoms of Pediatric CRS" lists nasal blockage/obstruction/congestion; nasal discharge/cough/facial pressure, which are identical to adults. These should be explained or changed.

In the abstract, it is stated that "we hypothesized that differences in the microbiome could be a cause of substantial differences in clinical features of the adult and pediatric populations." I do not see this as an hypothesis for the manuscript. It is a subject that may be addressed in the discussion and needs to be explained as above.

There is no overt hypothesis stated. On page 4 lines 28-31, The hypothesis of differences in adults and pediatric CRS being caused by microbiome differences is made, but this is not the subject addressed in the manuscript. The authors go on to "start testing our hypothesis" by characterizing differences. "Characterizing differences" is not an hypothesis. An hypothesis should be stated.

As a limitation, the use of unsheathed swabs (even those "collected carefully to avoid contamination") should be listed. It is a weakness and calls into question the microbiologic results eg the presence of staph epidermidis which may be a contaminant from the nasal vestibule.

I personally do not believe that a conclusion should begin with a claim that was not a subject of the manuscript eg "This is the first...". The conclusion should contain information that was shown to be true in the study.

It is also my personal opinion that claims of first discovery should not be made in a scientific manuscript.

Additionally, the statement in the conclusion that "we expect the results of our study to be helpful in explaining the differences in the pathogenesis of sinusitis in children and adults" appears to be an offhand comment not elucidated in the discussion section nor substantially addressed in the manuscript.

Minor Issues

The authors use the term "nasal cavity" at times which appears to refer to the site of culture. If the site of culture is in fact the middle meatus/anterior ethmoid, this is not the nasal cavity. Terminology should be consistent and meaningful and should be standardized.

"Uncultiveability" is used on page 12 which is not a word i am familiar with. It likely refers to "uncluturability" and should be reviewed and corrected.

All data was not presented in the manuscript or in an appendix, as far as could be seen ("data not shown").

In materials and methods, subject characteristics are listed (19 patients, males/females, age, etc). This information belongs in the Results section.

**********

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Reviewer #2: No

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8 Oct 2020

PLOS One

Comparison of the Human Microbiome in Adults and Children with Chronic Rhinosinusitis

Reviewer’s comments

Reviewer #1: This manuscript does represent a description of a novel comparison between adult and pediatric CRS that to date has not been presented in the literature. I believe this descriptive study is a useful foundation for exploration of the differences between the two diseases at a metagenomic level. The authors' limitations are clearly stated, namely that the patient numbers are small, and it is difficult to make causative conclusions based on the data presented here. The authors make appropriate conclusions based on the data presented. There are several papers looking at acute URIs and sinusitis in children with relation to baseline microbiome composition and microbiome-based interventions, but there is little in the literature looking specifically at pediatric CRS in otherwise healthy children, so this paper is unique.

Q1-1: It would be additionally useful to include more discussion of what the beta diversity findings mean--ie that children's microbial communities are more similar to each other than they are to adults. This would appeal to a broader audience without as much experience in microbiome research.

A : Thank you for your valuable suggestion. In accordance with your comment, we have modified our manuscript in discussion section and described. We also have added principal coordinate analysis (PCoA) figure.

(Page 15) However, beta diversity allowed researchers to dynamically visualize and compare two groups. In this study, UPGMA clustering of microbiome taxonomic profiles in both groups using the UniFrac distance, showed a relatively clear distinction between the two groups. All distance indices were visualized with principal coordinate analysis (PCoA) plots, which had two principal coordinates that explained the clear distance between samples (Fig 2(D)).

Fig 2 (D). Principal coordinate analysis (PCoA) plots showed two principal coordinates that explained the clear distance between samples.

There were a few changes I would make within the text:

Q1-2: Abstract:

"The bacterial 16S rRNA gene was pyrosequenced to compare the microbiota of the middle meatal." Would change to read middle meatus

A: Thank you for your comments. We have changed the word; “middle meatal” to “middle meatus” (in the abstract).

(Page 2) The bacterial 16S rRNA gene was pyrosequenced to compare the microbiota of the middle meatus.

Q1-3: Methods:

How was pediatric CRS defined? It would be useful to establish which symptoms/consensus statement definition was used for pediatric CRS, since these differ slightly compared to the adult European Position paper

A: Thank you for indicating valuable point. We have added some sentences in the revised manuscript as follows; (in the Methods session).

(Page 3-4) The symptoms of pediatric CRS differ from those of the adult CRS. According to the 2012 European position paper on rhinosinusitis and nasal polyps (EPOS) guidelines, persistent cough is an important symptom of CRS in children.

Q1-4: Figure 4: Legend mentions S. epidermidis but this is not represented in the figure

A: Thank you for your insightful comments. Mention about S. epidermidis was inserted by mistake. Inaccurate content in the figure legend was corrected.

Q1-5: Results: Page 11-12, lines 195-197

"While Corynebacterium showed a significantly higher relative abundance in the adult group, there was no difference in the abundance of Haemophilus in the adult group."

This is a little unclear. In comparison to the pediatric group?

A: Thanks for your valuable comments. As reviewer mentioned, above sentence is not clear. Above sentence was revised to the following

(Page 12) On comparing the two groups, we found that only Corynebacterium showed a significantly higher relative abundance in the adult group than in the pediatric group.

Q1-6: Discussion: page 13, lines 226-235

Important to clarify that these studies were done in adult CRS patients

A: Thank you for your insightful comments. We have added “adult” in the manuscript, to clarify that these studies were done in adult CRS patients.

(Page 13-14) A recent meta-analysis of studies comparing the composition of the bacterial microbiome in adult patients with CRS showed that the most abundant bacteria across all subjects were Staphylococcus, Propionibacterium, Corynebacterium, Streptococcus, and an unclassified lineage of Actinobacteria.[23] Another systemic review of a study of adult patients’ microbiome demonstrated that despite the significant heterogeneity of studies, certain phyla including Actinobacteria, Bacteroides, and Firmicutes were consistently present.[24] Corynebacterium and Staphylococcus were the most abundant genera among all adult CRS patients (29% and 16%, respectively) in a recent study conducted in Australia.[8]

Q1-7: Discussion: page 13, lines 240-241 Similar and very recently published paper. Stapleton AL, Shaffer AD, Morris A, Li K, Fitch A, Methé BA. The microbiome of pediatric patients with chronic rhinosinusitis. InInternational Forum of Allergy & Rhinology 2020 Apr 29. https://doi.org/10.1002/alr.22597

A: Thanks for your kind comments and for recommending literature. As following your comment, this paper was added to our paper in discussion section.

(Page 14) We found only one microbiome study of pediatric patients with CRS in the literature; Stapleton et al. reported that Moraxella, Haemophilus, and Streptococcus are the most abundant taxa in pediatric patients with CRS.[26] Furthermore, there was no significant difference in the microbial composition or diversity between pediatric patients and control subjects.[26]

Q1-8: Throughout the discussion, there are several conclusions about the relative abundance of specific species in the adult and pediatric populations, but this data is not presented or discussed in the results. It would be useful to present this data in the results section since so much of the discussion focuses on these data

A : Thanks for your great comments. And we have added results about the relative abundance of specific species in the adult and pediatric patients to the revised manuscript in Results section and we also have added supplement figure (Fig S1).

(Page 12) Furthermore, at the species level, Haemophilus influenzae (22.0%) was the most abundant in pediatric patients. Staphylococcus aureus (11.9%), Corynebacterium group (7.6%), Bacteroides vulgatus (7.1%), and Streptococcus pneumoniae (6.8%) were prevalent in the pediatric group. In adults, Corynebacterium spp., such as Corynebacterium accolens and Corynebacterium tuberculostearicum were the most abundant (23.7%), followed by Staphylococcus aureus (8.9%). (Fig S1)

Q1-9: Discussion: page 14, lines 265-268

This sentence is split into two with ‘and’ between limitations 2 and 3 and a period before limitation 4. Would combine into one full sentence.

A: Thank you for your great comment. We have revised the sentence and combined into one full sentence.

(Page 15) The limitations of our study are as follows: (1) we did not show data on healthy people in this study, (2) the sample sizes for each group were small, (3) we were unable to explain the difference between the group means, and (4) we were unable to interpret and clinically apply the antimicrobial sensitivities observed in this study. Nevertheless, this could be a significant comparative study of microbiomes between adult and pediatric CRS patients.

Reviewer #2: The manuscript appears to be technically sound and is well written and logical. The subject is pertinent and important in describing the microbiome in chronic rhinosinusitis (CRS) in adults and children. The methods appear to be well described. On its face, the results appear to be valid.

There are several features that bear revision.

Major Issues:

Q2-1: In the first sentence of the abstract, the authors state "Clinical features of pediatric CRS differ significantly from those of adult CRS", but this is not explained. Further, in the introduction on page 3 line 22, the same assertion is made. The study that is quoted (Silviu-Dan) contains a table of "Symptoms of Pediatric CRS" lists nasal blockage/obstruction/congestion; nasal discharge/cough/facial pressure, which are identical to adults. These should be explained or changed.

A: Thank you for indicating valuable point. We thought that the clinical characteristics of CRS in the point of treatment were significantly different. For example, the mainstay of treatment in pediatric CRS is medical treatment. If it is not effective, conservative surgery, such as adenoidectomy, may be considered. But, if medical treatment fails in adults, the surgeons may consider endoscopic sinus surgery immediately. All of pediatric CRS symptoms (you have mentioned above) is correct. However, according to EPOS 2012 guideline, the smell dysfunction (not cough) is included in the adult symptoms. According to your opinion, we have modified some sentences as follows: 1) we have removed first sentence of the abstract, and added some corrections in second sentence, 2) we have added some information regarding differences in the symptoms between adult and children.

(Page 2) We hypothesized that differences in the microbiome could be a cause of the substantial differences in the symptoms of and treatment options for adult and pediatric patients with chronic rhinosinusitis (CRS). First, we characterized the differences in the nasal microbiomes of pediatric and adult CRS patients.

Q2-2: In the abstract, it is stated that "we hypothesized that differences in the microbiome could be a cause of substantial differences in clinical features of the adult and pediatric populations." I do not see this as an hypothesis for the manuscript. It is a subject that may be addressed in the discussion and needs to be explained as above.

A: In last part of the introduction, we stated that this study is the first step toward proving our hypothesis. However, in the abstract we did not mention this. So above statement in abstract can cause misunderstanding and is not appropriate. We corrected abstract to fix it.

(Page 2) We hypothesized that differences in the microbiome could be a cause of the substantial differences in the symptoms of and treatment options for adult and pediatric patients with chronic rhinosinusitis (CRS). First, we characterized the differences in the nasal microbiomes of pediatric and adult CRS patients.

Q2-3: There is no overt hypothesis stated. On page 4 lines 28-31, The hypothesis of differences in adults and pediatric CRS being caused by microbiome differences is made, but this is not the subject addressed in the manuscript. The authors go on to "start testing our hypothesis" by characterizing differences. "Characterizing differences" is not an hypothesis. An hypothesis should be stated.

A: Thank you for your valuable suggestion. In accordance with your comment, we have modified our manuscript in introduction.

(Page 4) We hypothesized that differences in the microbiome could be a cause of the substantial differences between the adult and pediatric populations. In particular, we assumed that the nasal microbiome differed between the pediatric and adult patients with CRS. Therefore, in the present study, we investigated the bacterial abundance and diversity in children and adults with CRS and evaluated the differences between the two groups.

Q2-4: As a limitation, the use of unsheathed swabs (even those "collected carefully to avoid contamination") should be listed. It is a weakness and calls into question the microbiologic results eg the presence of staph epidermidis which may be a contaminant from the nasal vestibule.

A: Thank you for your insightful comments. However, we thought that the risk of contamination was very low because during swabbing, we used nasal speculum and endoscope and did not touch the anterior nostril and nasal vestibule.

We have described that how we've tried to lower the risk of contamination in the Material and Methods section.

Several researchers have reported that CRS patients had significantly increased bacterial abundance compared to control patients. S. aureus was the most prevalent organism in CRS patients, followed by S. epidermidis and Propionibacterium acnes [17]. (Mahdavinia M, Keshavarzian A, Tobin MC, Landay AL, Schleimer RP. A comprehensive review of the nasal microbiome in chronic rhinosinusitis (CRS). Clin Exp Allergy. 2016;46(1):21-41.)

(Page 4) Samples were collected carefully to avoid contamination from the anterior nostril, nasal vestibule and nasal cavity. During swabbing, we used nasal speculum and endoscope and did not touch the anterior nostril and nasal vestibule.

Q2-5: I personally do not believe that a conclusion should begin with a claim that was not a subject of the manuscript eg "This is the first...". The conclusion should contain information that was shown to be true in the study.

It is also my personal opinion that claims of first discovery should not be made in a scientific manuscript.

A: Thank you for your insightful comments. There is only one recently published microbiome study that was done in pediatric CRS patients. (Stapleton AL, Shaffer AD, Morris A, Li K, Fitch A, Methé BA. The microbiome of pediatric patients with chronic rhinosinusitis. InInternational Forum of Allergy & Rhinology 2020, E-pub). This paper was added to our manuscript in discussion section. There are no comparative study of the microbiomes between adult and pediatric CRS patients. However, as you mentioned, the claims of first discovery should not be made in a scientific manuscript. We have modified our manuscript in discussion section.

(Page 15) Nevertheless, this could be a significant comparative study of microbiomes between adult and pediatric CRS patients.

Q2-6: Additionally, the statement in the conclusion that "we expect the results of our study to be helpful in explaining the differences in the pathogenesis of sinusitis in children and adults" appears to be an offhand comment not elucidated in the discussion section nor substantially addressed in the manuscript.

A: Thank you for your great comment. We have modified that sentence.

(Page 16) we expect the results of our study to help broaden the understanding of pediatric and adult CRS.

Minor Issues

Q2-7: The authors use the term "nasal cavity" at times which appears to refer to the site of culture. If the site of culture is in fact the middle meatus/anterior ethmoid, this is not the nasal cavity. Terminology should be consistent and meaningful and should be standardized.

A: Thank you for your comment. We have modified the terms (esp. in the figure legends.)

Q2-8: "Uncultiveability" is used on page 12 which is not a word i am familiar with. It likely refers to "uncluturability" and should be reviewed and corrected.

A: Thank you for your valuable comment. We have modified that sentence.

(Page 13) It is known that there can be nearly a 99% chance that the bacteria will not be cultured,

Q2-9: All data was not presented in the manuscript or in an appendix, as far as could be seen ("data not shown").

A: Richness and Alpha diversity can be shown by several methods. Because all indexes showed similar results, we showed only representative indexes method in the graph. We thought graphs of other indexes are redundant, so showed only p-value of other indexes.

Q2-10: In materials and methods, subject characteristics are listed (19 patients, males/females, age, etc). This information belongs in the Results section.

A: Thank you for your valuable suggestion. In accordance with your comment, we have modified our manuscript in results section.

Results

Subjects and Sequence Reads Counts

(Page 7-8) Swabs were obtained from 19 patients (9 children and 10 adults); pediatric patients comprised five males and four females (mean age 9.7 ± 3.7), while adult patients comprised five males and five females (mean age 46 ± 14.6).

Submitted filename: Reviewer s comments_Response letter_PLOS One_20201007.docx

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10 Nov 2020

Comparison of the Human Microbiome in Adults and Children with Chronic Rhinosinusitis

PONE-D-20-20970R1

Dear Dr. Hong,

We’re pleased to inform you that your manuscript has been judged scientifically suitable for publication and will be formally accepted for publication once it meets all outstanding technical requirements.

Within one week, you’ll receive an e-mail detailing the required amendments. When these have been addressed, you’ll receive a formal acceptance letter and your manuscript will be scheduled for publication.

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Additional Editor Comments (optional):

Thank you for your revised version of your initial manuscript "Comparison of the Human Microbiome in Adults and Children with Chronic Rhinosinusitis"

I applaud your efforts for addressing the concerns of the reviewers and believe that they have all been addressed

Reviewers' comments:

Reviewer's Responses to Questions

Comments to the Author

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Reviewer #1: All comments have been addressed

Reviewer #2: All comments have been addressed

**********

2. Is the manuscript technically sound, and do the data support the conclusions?

The manuscript must describe a technically sound piece of scientific research with data that supports the conclusions. Experiments must have been conducted rigorously, with appropriate controls, replication, and sample sizes. The conclusions must be drawn appropriately based on the data presented.

Reviewer #1: Yes

Reviewer #2: Yes

**********

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Reviewer #1: Yes

Reviewer #2: Yes

**********

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Reviewer #1: Yes

Reviewer #2: Yes

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PLOS ONE does not copyedit accepted manuscripts, so the language in submitted articles must be clear, correct, and unambiguous. Any typographical or grammatical errors should be corrected at revision, so please note any specific errors here.

Reviewer #1: Yes

Reviewer #2: Yes

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Please use the space provided to explain your answers to the questions above. You may also include additional comments for the author, including concerns about dual publication, research ethics, or publication ethics. (Please upload your review as an attachment if it exceeds 20,000 characters)

Reviewer #1: (No Response)

Reviewer #2: Comments were nicely addressed. The manuscript is technically sound, well written, and intelligible.

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Reviewer #1: No

Reviewer #2: Yes: Andrew N. Goldberg, MD, MSCE

19 Nov 2020

PONE-D-20-20970R1

Comparison of the Human Microbiome in Adults and Children with Chronic Rhinosinusitis

Dear Dr. Hong:

I'm pleased to inform you that your manuscript has been deemed suitable for publication in PLOS ONE. Congratulations! Your manuscript is now with our production department.

If your institution or institutions have a press office, please let them know about your upcoming paper now to help maximize its impact. If they'll be preparing press materials, please inform our press team within the next 48 hours. Your manuscript will remain under strict press embargo until 2 pm Eastern Time on the date of publication. For more information please contact onepress@plos.org.

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