Oropharyngeal microbiome of an HIV-positive patient

Clinical and Microbial Determinants of Upper Respiratory Colonization With Streptococcus pneumoniae and Native Microbiota in People With Human Immunodeficiency Virus Type 1 and Control Adults

BACKGROUND

The substantial risk for respiratory and invasive infections with Streptococcus pneumoniae (Spn) among people with HIV-1 (PWH) begins with asymptomatic colonization. The frequency of Spn colonization among US adults with and without HIV-1 infection is not well characterized in the conjugate vaccine era.

METHODS

We determined Spn colonization frequency by culture and specific lytA gene quantitative polymerase chain reaction (PCR) and microbiota profile by 16S ribosomal RNA gene sequencing in nasopharyngeal (NP) and oropharyngeal (OP) DNA from 138 PWH and 93 control adults and associated clinical characteristics.

RESULTS

The frequencies of Spn colonization among PWH and controls did not differ (11.6% vs 8.6%, respectively; P = .46) using combined results of culture and PCR, independent of vaccination or behavioral risks. PWH showed altered microbiota composition (ie, β-diversity; NP: P = .0028, OP: P = .0098), decreased α-diversity (NP: P = .024, OP: P = .0045), and differences in the relative abundance of multiple bacterial taxa. Spn colonization was associated with altered β-diversity in the nasopharynx (P = .011) but not oropharynx (P = .21).

CONCLUSIONS

Despite widespread conjugate vaccine and antiretroviral use, frequencies of Spn colonization among PWH and controls are currently consistent with those reported in the preconjugate era. The persistently increased risk of pneumococcal disease despite antiretroviral therapy may relate to behavioral and immunologic variables other than colonization.

Narrative review of application of metagenomic approaches to study the link between oropharyngeal microbiome and infectious diseases

Context

Viral and bacterial infections are major causes of morbidity and mortality worldwide. The oropharyngeal microbiome could play an important role in preventing invasion of viral and bacterial pathogens by modulating its content and the host's innate immune response. Next Generation Sequencing (NGS) technologies now enable in-depth study of the genomes of microbial communities. The objective of this review is to highlight how metagenomics has contributed to establish links between changes in the oropharyngeal microbiome and emergence of bacterial and viral diseases.

Method

Two search engines, PubMed and Google scholar were used with filters to focus searches on peer-reviewed original articles published between January 2010 and September 2022. Different keywords were used and only articles with metagenomic approaches were included.

Results

This review shows that there were few articles studying the link between oropharyngeal microbiome and infectious diseases. Studies on viruses using metagenomic techniques have been growing exponentially in recent years due to the Covid-19 pandemic. This review shows that most studies still focus on the basic identification of microorganisms in different disease states and multiple microorganisms (Alloprevotella, Prevotella, Bacteroides, Haemophilus, Streptococcus, Klebsiella sp., Acinetobacter sp…), have been associated with development of infections such as childhood wheezing, influenza, Covid-19, pneumonia, meningitis, and tuberculosis.

Conclusion

The oropharyngeal microbiome, despite its importance, remains poorly studied. A limited number of articles were identified but this number has increased exponentially since 2020 due to research conducted on Covid-19. These studies have shown that metagenomic has contributed to the unbiased identification of bacteria that could be used as biomarkers of various diseases and that further research is now needed to capitalize on those findings for human health benefit.

Role of a probiotic strain in the modulation of gut microbiota and cytokines in inflammatory bowel disease

OBJECTIVE

To assess the effect of a probiotic strain Bacillus clausii UBBC-07 on gut microbiota and cytokines in IBD patients.

METHOD

Patients were randomly allocated to either placebo or probiotic Bacillus clausii UBBC-07 for four weeks along with the standard medical treatment (SMT). Enrolled patients were evaluated before and after intervention for presence of the given probiotic, change in gut microbiota, change in serum cytokines, serotonin and dopamine, symptoms of disease, physical, behavioral and psychological parameters.

RESULTS

Probiotic strain Bacillus clausii UBBC-07 showed good survival in IBD patients in the treatment group (p < 0.01) without any reported adverse event. Metagenomic analysis showed that the given probiotic strain was able to modulate the gut microbiota in treated group. Phylum Firmicutes was increased and phylum Bacteroidetes was decreased in the probiotic treated group. A significant increase was observed in the abundance of anaerobic bacterial genera Lactobacillus, Bifidobacterium and Faecalibacterium in the probiotic treated group (p < 0.01) as compared to placebo group. Significant increase was observed in IL-10 (p < 0.05) and variable decrease in the secretion of IL-1β, TNF- α, IL-6, IL -17 and IL -23 in probiotic treated group. In the treatment group a significant decrease in the symptoms of IBD and improvement in the psychological parameter to various degrees was noted.

CONCLUSION

These results indicated that probiotic strain B clausii UBBC-07 affected the gut microbiota and cytokine secretion and shown efficacy in IBD patients.

SARS-CoV-2 and Prevotella spp.: friend or foe? A systematic literature review

During this global pandemic of the COVID-19 disease, a lot of information has arisen in the media and online without scientific validation, and among these is the possibility that this disease could be aggravated by a secondary bacterial infection such as Prevotella, as well as the interest or not in using azithromycin, a potentially active antimicrobial agent. The aim of this study was to carry out a systematic literature review, to prove or disprove these allegations by scientific arguments. The search included Medline, PubMed, and Pubtator Central databases for English-language articles published 1999-2021. After removing duplicates, a total of final eligible studies (n=149) were selected. There were more articles showing an increase of Prevotella abundance in the presence of viral infection like that related to Human Immunodeficiency Virus (HIV), Papillomavirus (HPV), Herpesviridae and respiratory virus, highlighting differences according to methodologies and patient groups. The arguments for or against the use of azithromycin are stated in light of the results of the literature, showing the role of intercurrent factors, such as age, drug consumption, the presence of cancer or periodontal diseases. However, clinical trials are lacking to prove the direct link between the presence of Prevotella spp. and a worsening of COVID-19, mainly those using azithromycin alone in this indication.

Unraveling of Chlorella-associated bacterial load, diversity, and their imputed functions at high- and low-yield conditions through metagenome sequencing

Chlorella-associated bacteria can have a significant influence on facilitating higher Chlorella biomass yield due to their symbiotic relationship. In this study, non-axenic Chlorella was cultivated in an airlift photobioreactor at high and low-yield conditions. The associated bacterial diversity was analyzed using 16S rRNA metagenome sequencing. At high-yield conditions, the bacterial load was observed in the range of 10⁸ -10¹⁰ CFU · mL^-1 , whereas at low-yield conditions, bacteria were more dominant and observed in the range of 10¹⁴ -10¹⁵  CFU · mL^-1 . The majority of the bacterial species associated with Chlorella at high-yield conditions belongs to Proteobacteria and Bacteroidetes. Further, Bacteroidetes levels were decreased at low-yield conditions and were highly diversified with Planctomycetes, Firmicutes, and 18 others. Predicted functional genes indicated that Chlorella-associated bacteria have the enzymes involved in the metabolism and biosynthesis of B-complex vitamins (i.e., vitamin B₁₂ , thiamin, biotin, pyridoxine, and riboflavin). A critical evaluation revealed that vitamin biosynthesis genes were more abundant at low-yield conditions; however, vitamin B₁₂ transport genes (B₁₂ transport ATP-binding protein, B₁₂ substrate-binding transportation, and B₁₂ permease protein) were less abundant, indicating even though vitamins production occurs, but their availability to Chlorella was limited due to the lack of vitamin transport genes. Further, at high yield, Chlorella-associated bacteria enabled higher growth by supplementing the vitamins. In contrast, at low-yield condition-an increased bacterial load, diversity, and limited vitamin transport functional genes affected the Chlorella yield. It can be inferred that Chlorella yield was significantly affected by three factors: associated bacterial load, diversity, and transport functional genes of vitamins.

Dual and mutual interaction between microbiota and viral infections: a possible treat for COVID-19

All of humans and other mammalian species are colonized by some types of microorganisms such as bacteria, archaea, unicellular eukaryotes like fungi and protozoa, multicellular eukaryotes like helminths, and viruses, which in whole are called microbiota. These microorganisms have multiple different types of interaction with each other. A plethora of evidence suggests that they can regulate immune and digestive systems and also play roles in various diseases, such as mental, cardiovascular, metabolic and some skin diseases. In addition, they take-part in some current health problems like diabetes mellitus, obesity, cancers and infections. Viral infection is one of the most common and problematic health care issues, particularly in recent years that pandemics like SARS and COVID-19 caused a lot of financial and physical damage to the world. There are plenty of articles investigating the interaction between microbiota and infectious diseases. We focused on stimulatory to suppressive effects of microbiota on viral infections, hoping to find a solution to overcome this current pandemic. Then we reviewed mechanistically the effects of both microbiota and probiotics on most of the viruses. But unlike previous studies which concentrated on intestinal microbiota and infection, our focus is on respiratory system's microbiota and respiratory viral infection, bearing in mind that respiratory system is a proper entry site and residence for viruses, and whereby infection, can lead to asymptomatic, mild, self-limiting, severe or even fatal infection. Finally, we overgeneralize the effects of microbiota on COVID-19 infection. In addition, we reviewed the articles about effects of the microbiota on coronaviruses and suggest some new therapeutic measures.