Global trends in gut microbiota and clostridioides difficile infection research: A visualized study

Linked mutations within the pathogenicity locus of Clostridioides difficile increase virulence

BACKGROUND

The clinical manifestations of Clostridioides difficile infections range from diarrhoea to pseudomembranous colitis (PMC) and death. We evaluated the association between gene content in C. difficile clinical isolates and disease severity.

METHODS

Fifty-three C. difficile isolates were subjected to Sanger sequencing, clinical data were used to analyse the association of gene content with disease severity, and 83 non-duplicate isolates were collected to confirm the results. Virulence was further examined by functional in vitro and in vivo experiments.

RESULTS

Among the 53 C. difficile isolates, ribotypes 017 (n = 9, 17.0%) and 012 (n = 8, 15.1%) were predominant. Fifteen strains exhibited a correlation between mutations of pathogenicity locus genes (tcdB, tcdC, tcdR, and tcdE) and were named linked-mutation strains. Ribotypes are not associated with clinical PMC and Linked-mutation strains. The proportion of patients with PMC was higher in the group infected with linked-mutation strains than in the non-linked-mutation group (57.14% vs. 0%, p < 0.001). The linked-mutation rate of C. difficile was higher in patients with PMC than in patients without PMC (89.47% vs. 7.8%, p < 0.0001). Linked-mutation strains showed greater cytotoxicity in vitro and caused more severe tissue damage in a mouse model.

CONCLUSIONS

Linked-mutation strains are associated with high virulence and PMC development. This result will help monitor the clinical prognosis of C. difficile infection and provide key insights for developing therapeutic targets and monoclonal antibodies.

Budesonide, an anti-inflammatory drug, exacerbate clostridioides difficile colitis in mice

BACKGROUND AND AIMS

Clostridioides difficile infection (CDI) induces intense acute inflammatory responses through toxin release. A combination of antibiotic and anti-inflammatory agents is sometimes recommended in severe, non-responsive cases, although clinical trials have been inconclusive, raising concerns about potential complications. This study aims to investigate the effect of budesonide and mesalamine in the treatment of CDI in a murine model, by evaluating the combination of fidaxomicin and these anti-inflammatory drugs.

METHOD

C57BL/6 J female mice pretreated with an antimicrobial mixture were challenged with C. difficile VPI 10463 or culture media by gavage. After the challenge, mice received placebo, fidaxomicin alone (20 mg/kg), or fidaxomicin combined with mesalamine (200, 400 mg/kg) or budesonide (0.2, 1, 10 mg/kg) for 5 days. The mice were monitored for 7 days with weight and survival. Colon and cecum tissues were harvested for histological assessment.

RESULTS

CDI of mice caused 80% mortality. Fidaxomicin completely protected against CDI in all parameters (weight, survival and pathscores). Mortality rates were up to 90%, 70% in budesonide(10 mg/kg) and mesalamine (400 mg/kg) treatment group, respectively. Budesonide (0.02,0.1 and 1 mg/kg) adjunction to fidaxomicin worsened the disease outcome according to all tested parameters. While mesalamine in combination with fidaxomicin (200, 400 mg/kg) did not lead to any deaths during CDI treatment, it did not provide additional benefits.

CONCLUSIONS

Anti-inflammatory drugs including corticosteroid therapy may worsen the incidence and severity of CDI in this mouse model. These studies may have important clinical implications for understanding the role of anti-inflammatory/ corticosteroid therapy in CDI and inflammatory bowel disease management.

Gut microbiota and autism spectrum disorders: where do we stand?

BACKGROUND

Children with autism spectrum disorder (ASD) often have digestive problems and microbial imbalances in their guts, suggesting that these conditions may play a role in the development of the disorder. Scopus-based research on the gut microbiota and ASD was examined in this bibliometric analysis to shed light on the current state of research and identify potential hotspots for future work in this area.

METHODS

We searched documents from the Scopus database and reference citation analysis to collect published data on the gut microbiota and ASD from 2003 to 2022. The downloaded document records were exported to VOSviewer v.1.6.19 to examine and visualize the collaboration between countries and determine the research hotspots.

RESULTS

The search yielded 958 articles specifically dedicated to gut microbiota and ASD. The number of publications in this field increased rapidly after 2013, with a peak in 2022. The United States (n = 267; 27.87%) was the most active country, followed by China (n = 171; 17.85%) and Italy (n = 96; 10.02). International collaboration was observed, with the USA playing a central role. University College Cork, Ireland, was the most productive institution (n = 24; 2.51%). The National Natural Science Foundation of China was the most active funding agency (n = 76; 7.93%). Nutrients journal had the highest number of publications (n = 28; 2.92%). The articles related to gut microbiota and ASD were highly cited, with an h-index of 108. The research themes identified focused on the modulation of gut microbiota as a potential therapy for children with ASD and gut-brain axis dysfunction in ASD.

CONCLUSIONS

In recent years, the study of gut microbiota and its association with ASD has garnered considerable interest as an emergent field of study. The results of this study substantially enhance our current understanding of the knowledge landscape in this field and illuminate potential avenues for future research. It is essential to emphasize the significance of devoting more resources to the newest and most promising research areas, such as investigating the potential therapeutic benefits of modulating the intestinal microbiota in children with ASD. This research has enormous potential and merits intensified focus and investigation.

Clostridioides difficile resistance to antibiotics, including post-COVID-19 data

INTRODUCTION

Updating data on Clostridioides difficile antibiotic resistance is important for treatment improvement of C. difficile infections (CDIs).

AREAS COVERED

Results from 20 countries were included. The mean resistance to 2 mg/l vancomycin, 2 mg/l metronidazole, 4 mg/l moxifloxacin, and 4 mg/l clindamycin was 4.7% (0 to ≥ 26% in two studies), 2.6% (0 to ≥ 40% in 3 studies), 34.9% (6.6->80%), and 61.0% (30->90%), respectively. Resistance to erythromycin (>60-88%), rifampin (>23-55.0%), imipenem (0.6 to > 78% in a clone), tigecycline (0-<5.0%), and fidaxomicin (0-2%) was also found. Resistance to ≥ 5 antibiotics of different classes was reported in some countries. High resistance and multidrug resistance were observed in hypervirulent and epidemic strains. Although only 1% of COVID-19 patients had CDIs, the proportion might be underestimated.

EXPERT OPINION

C. difficile antimicrobial susceptibility varied by country/region, study period, and circulating ribotypes. For CDI treatment, fidaxomicin (preferably) or vancomycin is recommended, while metronidazole is suitable for mild infections. New approaches, including biotherapeutics (Rebyota), strains, antibiotics (ridinilazole and ibezapolstat), and monoclonal antibodies/cocktails merit further evaluation. Because of the resistance rate variations, C. difficile antibiotic susceptibility should be regularly monitored. Post-COVID-19 resistance should be separately presented. Some discrepancies between vancomycin and metronidazole results need to be clarified.

Mapping knowledge landscapes and emerging trends of sonodynamic therapy: A bibliometric and visualized study

Background: Ultrasound-triggered sonodynamic therapy (SDT), as a non-invasive approach, has attracted considerable attention in a wide variety of malignant tumors and other diseases. Over the past 2 decades, the number of scientific publications on SDT has increased rapidly. However, there is still a lack of one comprehensive report that summarizes the global research trends and knowledge landscapes in the field of SDT in detail. Thus, we performed a bibliometric analysis on SDT from 2000 to 2021 to track the current hotspots and highlight future directions. Methods: We collected publications on SDT research from the Web of Science Core Collection database. The annual number of publications and citations, major contributors, popular journals, international collaborations, co-cited references and co-occurrence keywords were analyzed and visualized with CiteSpace, VOSviewer, and R-bibliometrix. Results: A total of 701 publications were included. The annual publication output increased from 5 in 2000 to 175 in 2021, and the average growth rate was 18.4%. China was the most productive country with 463 documents (66.05%), and Harbin Medical University was the most prolific institution (N = 73). Ultrasound in Medicine and Biology published the most papers related to SDT. Materials Science, and Chemistry were the research areas receiving the most interest. All the keywords were divided into four different clusters including studies on mechanisms, studies on drug delivery and nanoparticles, studies on cancer therapy, as well as studies on ultrasound and sonosensitizers. In addition to nanomaterials-related studies including nanoparticles, mesoporous silica nanoparticles, nanosheets, liposomes, microbubble and TiO₂ nanoparticle, the following research directions such as immunogenic cell death, metal-organic framework, photothermal therapy, hypoxia, tumor microenvironment, chemodynamic therapy, combination therapy, tumor resistance, intensity focused ultrasound, drug delivery, and Staphylococcus aureus also deserve further attention and may continue to explode in the future. Conclusion: SDT has a bright future in the field of cancer treatment, and nanomaterials have increasingly influenced the SDT field with the development of nano-technology. Overall, this comprehensive bibliometric study was the first attempt to analyze the field of SDT, which could provide valuable references for later researchers to better understand the global research trends, hotspots and frontiers in this domain.

Global trends in Akkermansia muciniphila research: A bibliometric visualization

BACKGROUND

Akkermansia muciniphila is a member of the gut microbiome, using mucin as sources of carbon, nitrogen, and energy. Since the first discovery of this unique bacterium in 2004, A. muciniphila has been extensively studied. It is considered a promising "next-generation beneficial microbe." The purpose of this paper is to sort out the research status and summarize the hotspots through bibliometric analysis of the publications of A. muciniphila.

METHODS

The publications about A. muciniphila from January 2004 to February 2022 were obtained from the Web of Science Core Collection. Visualization analyses were performed using three bibliometric tools and GraphPad Prism.

RESULTS

A total of 1,478 published documents were analyzed. Annual publication number grew from 1 in 2004 to 336 in 2021, with China being the leading producer (33.36%). De Vos, Willem M was the most productive author with the highest H-index (documents = 56, H-index = 37), followed by Cani, Patrice D (documents = 35, H-index = 25). And Scientific Reports published the most papers. PNAS was the keystone taxa in this field, with high betweenness centrality (0.11) and high frequency. The keywords with high frequency in recent years include: oxidative stress, diet, metformin, fecal microbiota transplantation, short-chain fatty acids, polyphenols, microbiota metabolites and so on. The keyword "oxidative stress" was observed to be increasing in frequency recently.

CONCLUSION

Over time, the scope of the research on the clinical uses of A. muciniphila has gradually increased, and was gradually deepened and developed toward a more precise level. A. muciniphila is likely to remain a research hotspot in the foreseeable future and may contribute to human health.