Human nasal microbiota

Altered nasal and oral microbiomes define pediatric sickle cell disease

Sickle cell disease (SCD) is a chronic blood disorder that disrupts multiple organ systems and can lead to severe morbidity. Persistent and acute symptoms caused by immune system dysregulation in individuals with SCD could contribute to disease either directly or indirectly via dysbiosis of commensal microbes and increased susceptibility to infection. Here, we explored the nasal and oral microbiomes of children with SCD (cwSCD) to uncover potential dysbiotic associations with the blood disorder. Microbiota collected from nasal and oral swabs of 40 cwSCD were compared to eight healthy siblings using shotgun metagenomic sequencing. Commensal taxa were present at similar levels in the nasal and oral microbiome of both groups. However, the nasal microbiomes of cwSCD contained a higher prevalence of Pseudomonadota species, including pathobionts such as Yersinia enterocolitica and Klebsiella pneumoniae. Furthermore, the oral microbiome of cwSCD displayed lower α-diversity and fewer commensal and pathobiont species compared to the healthy siblings. Thus, subtle but notable shifts seem to exist in the nasal and oral microbiomes of cwSCD, suggesting an interaction between SCD and the microbiome that may influence health outcomes.

IMPORTANCE

The oral and nasal cavities are susceptible to environmental exposures including pathogenic microbes. In individuals with systemic disorders, antibiotic exposure, changes to the immune system, or changes to organ function could influence the composition of the microbes at these sites and the overall health of individuals. Children with sickle cell disease (SCD) commonly experience respiratory infections, such as pneumonia or sinusitis, and may have increased susceptibility to infection because of disrupted microbiota at these body sites. We found that children with SCD (cwSCD) had more pathobiont bacteria in the nasal cavity and reduced bacterial diversity in the oral cavity compared to their healthy siblings. Defining when, why, and how these changes occur in cwSCD could help identify specific microbial signatures associated with susceptibility to infection or adverse outcomes, providing insights into personalized treatment strategies and preventive measures.

The Respiratory Tract Microbiome and Human Health

The respiratory tract microbiome (RTM) is a multi-kingdom microbial ecosystem that inhabits various niches of the respiratory system. While previously overlooked, there is now sufficient evidence that the RTM plays a crucial role in human health related to immune system training and protection against pathogens. Accordingly, dysbiosis or disequilibrium of the RTM has been linked to several communicable and non-communicable respiratory diseases, highlighting the need to unveil its role in health and disease. Here, we define the RTM and its place in microbiome medicine. Moreover, we outline the challenges of RTM research, emphasising the need for combining methodologies, including multi-omics and computational tools. We also discuss the RTM's potential for diagnosing, preventing and treating respiratory diseases and developing novel microbiome-based therapies to improve pulmonary health.

Nasal microbiota transplantation: a gateway to novel treatments

Two recent studies have highlighted the potential of nasal microbiota transplantation (NMT) to treat chronic rhinosinusitis (CRS). Here we evaluate these findings and propose that lessons from fecal microbiota transplantation (FMT) could guide NMT development, with possible implications for combating antimicrobial resistance in respiratory infections.

Prolonged mask wearing changed nasal microbial characterization of young adults during the COVID-19 pandemic in Shanghai, China

Background

Face masks have become a common sight during the Coronavirus Disease 2019 (COVID-19) pandemic in many countries. However, the impact of prolonged face mask wearing on nasal microbiota of healthy people is not fully understood.

Methods

In this study, we compared the nasal microbiota of 82 young adults who wore face masks for an extended period of time to 172 mask-free peers from the same school recruited before the COVID-19 pandemic via 16S ribosomal RNA gene sequencing. Diversity, composition, and function of nasal microbiota between the two groups were analyzed. Prevalence of commensal bacteria colonized in the nasal cavity was determined by culture-based analysis.

Results

We observed that prolonged face mask wearers had significantly different nasal microbial characterization and metabolic function compared to mask-free controls from 2018. Specifically, the nasal microbiota of the prolonged mask wearers displayed increased abundance of Staphylococcus, Pseudoalteromonas, Corynebacterium, etc. Meanwhile, the abundance of several genera including Bacteroides, Faecalibacterium, and Agathobacter was decreased. Moreover, we observed that COVID-19 infection history did not affect the composition of nasal microbiota significantly. Additionally, the culture-based analysis revealed that Staphylococcus aureus and Corynebacterium accolens increased, and Staphylococcus epidermidis decreased in the nasal cavity of prolonged mask wearers.

Conclusions

Overall, our study suggests that prolonged face mask wearing can significantly alter the nasal microbiota.

The Role of Indoor Microbiome and Metabolites in Shaping Children's Nasal and Oral Microbiota: A Pilot Multi-Omic Analysis

Maintaining a diverse and well-balanced nasal and oral microbiota is vital for human health. However, the impact of indoor microbiome and metabolites on nasal and oral microbiota remains largely unknown. Fifty-six children in Shanghai were surveyed to complete a questionnaire about their personal and environmental characteristics. The indoor microbiome and metabolites from vacuumed indoor dust were profiled via shotgun metagenomics and untargeted liquid chromatography-mass spectrometry (LC-MS). The nasal and oral microbiota in children was characterized using full-length 16S rRNA sequencing from PacBio. Associations between personal/environmental characteristics and the nasal/oral microbiota were calculated using PERMANOVA and regression analyses. We identified 6247, 431, and 342 microbial species in the indoor dust, nasal, and oral cavities, respectively. The overall nasal and oral microbial composition showed significant associations with environmental tobacco smoke (ETS) exposure during pregnancy and early childhood (p = 0.005 and 0.03, respectively), and the abundance of total indoor flavonoids and two mycotoxins (deoxynivalenol and nivalenol) (p = 0.01, 0.02, and 0.03, respectively). Notably, the abundance of several flavonoids, such as baicalein, eupatilin, isoliquiritigenin, tangeritin, and hesperidin, showed positive correlations with alpha diversity and the abundance of protective microbial taxa in nasal and oral cavities (p < 0.02), suggesting their potential beneficial roles in promoting nasal/oral health. Conversely, high carbohydrate/fat food intake and ETS exposure diminished protective microorganisms while augmenting risky microorganisms in the nasal/oral cavities. Further, potential microbial transfer was observed from the indoor environment to the childhood oral cavity (Moraxella catarrhalis, Streptococcus mitis, and Streptococcus salivarius), which could potentially increase virulence factors related to adherence and immune modulation and vancomycin resistance genes in children. This is the first study to reveal the association between the indoor microbiome/metabolites and nasal/oral microbiota using multi-omic approaches. These findings reveal potential protective and risk factors related to the indoor microbial environment.

What We Learn from Surveillance of Microbial Colonization in Recipients of Pediatric Hematopoietic Stem Cell Transplantation

Infections in hematopoietic stem cell transplant (HSCT) remain one of the major causes for morbidity and mortality, and it is still unclear whether knowledge of microbial colonization is important. In this single-center study, we collected weekly surveillance cultures in pediatric recipients of allogenic HSCT from five different body regions and tested for bacteria and fungi. Between January 2010 and December 2021, we collected 1095 swabs from 57 recipients of allogeneic HSCTs (median age: 7.5 years, IQR 1−3: 2.5−11.9). The incidence of positive microbiological cultures (n = 220; 20.1%) differed according to the anatomic localization (p < 0.001) and was most frequent in the anal region (n = 98), followed by the genital, pharyngeal and nasal regions (n = 55, n = 37 and n = 16, respectively). Gram-positive bacteria (70.4%) were the most commonly isolated organisms, followed by fungi (18.6%), Gram-negative (5.5%), non-fermenting bacteria (1.4%), and other flora (4.1%). No association with increased risk of infection (n = 32) or septicemia (n = 7) was noted. Over time, we did not observe any increase in bacterial resistance. We conclude that there is no benefit to surveillance of microbial colonization by culture-based techniques in pediatric HSCT. Sequencing methods might enhance the detection of pathogens, but its role is still to be defined.

Deleterious Effect of Air Pollution on Human Microbial Community and Bacterial Flora: A Short Review

A balanced microbiota composition is requisite for normal physiological functions of the human body. However, several environmental factors such as air pollutants may perturb the human microbiota composition. It is noticeable that currently around 99% of the world's population is breathing polluted air. Air pollution's debilitating health impacts have been studied scrupulously, including in the human gut microbiota. Nevertheless, air pollution's impact on other microbiotas of the human body is less understood so far. In the present review, the authors have summarized and discussed recent studies' outcomes related to air pollution-driven microbiotas' dysbiosis (including oral, nasal, respiratory, gut, skin, and thyroid microbiotas) and its potential multi-organ health risks.

The diagnostic value of nasal microbiota and clinical parameters in a multi-parametric prediction model to differentiate bacterial versus viral infections in lower respiratory tract infections

Background

The ability to accurately distinguish bacterial from viral infection would help clinicians better target antimicrobial therapy during suspected lower respiratory tract infections (LRTI). Although technological developments make it feasible to rapidly generate patient-specific microbiota profiles, evidence is required to show the clinical value of using microbiota data for infection diagnosis. In this study, we investigated whether adding nasal cavity microbiota profiles to readily available clinical information could improve machine learning classifiers to distinguish bacterial from viral infection in patients with LRTI.

Results

Various multi-parametric Random Forests classifiers were evaluated on the clinical and microbiota data of 293 LRTI patients for their prediction accuracies to differentiate bacterial from viral infection. The most predictive variable was C-reactive protein (CRP). We observed a marginal prediction improvement when 7 most prevalent nasal microbiota genera were added to the CRP model. In contrast, adding three clinical variables, absolute neutrophil count, consolidation on X-ray, and age group to the CRP model significantly improved the prediction. The best model correctly predicted 85% of the ‘bacterial’ patients and 82% of the ‘viral’ patients using 13 clinical and 3 nasal cavity microbiota genera (Staphylococcus, Moraxella, and Streptococcus).

Conclusions

We developed high-accuracy multi-parametric machine learning classifiers to differentiate bacterial from viral infections in LRTI patients of various ages. We demonstrated the predictive value of four easy-to-collect clinical variables which facilitate personalized and accurate clinical decision-making. We observed that nasal cavity microbiota correlate with the clinical variables and thus may not add significant value to diagnostic algorithms that aim to differentiate bacterial from viral infections.

Alantolactone: A sesquiterpene lactone with diverse pharmacological effects

Alantolactone (Ala) is a sesquiterpene lactone that can be isolated from many herbal plants belonging to Asteraceae. Besides the antimicrobial activities against bacteria, fungi and viruses, Ala has also demonstrated significant anti-inflammatory effects in various models by inhibiting NF-κB and MAPKs to decrease the pro-inflammatory cytokines such as IL-1β, IL-6 and TNF-α. The antitumor effects of Ala have been demonstrated in vitro and in vivo via inducing intrinsic apoptosis, oxidative stress, ER stress, cell cycle arrest and inhibiting autophagy and STAT3 phosphorylation, which are also involved in its combination or synergy with other antitumor drugs. Ala also has neuroprotective activity through attenuating oxidative stress and inflammation, besides its modulation of glucose and lipid metabolism. This review summarizes the recent advances of the pharmacological effects of Ala, including anti-inflammatory, antitumor, antimicrobial, neuroprotective activities, as well as the underlying mechanisms. Ala might be employed as a potential lead to develop drugs for multiple diseases.