Enterotoxic Clostridia: Clostridioides difficile Infections

Testing and Diagnosis of Clostridioides difficile Infection in Special Scenarios: A Systematic Review

INTRODUCTION

Clostridioides difficile infection (CDI) is a clinical and laboratory diagnosis. Populations at higher risk of developing disease require a high clinical index of suspicion for laboratory testing to avoid incorrect assumptions of colonization. Common risk factors include recent antibiotic use, elderly (>65 years old), and immunocompromised patients. C. difficile assays should be ordered in an algorithm approach to diagnose an infection rather than colonization. Screening tests are widely available in hospital systems, but novel molecular testing may aid in diagnosis in patients with inconclusive or discordant antigen and toxin test results.  Methods: Data was extracted from PubMed, Scopus, and Cumulative Index of Nursing and Allied Health Literature (CINAHL) databases based on the keywords "clostridioides difficile", "toxin assay", and "toxic megacolon". The data extracted is based on the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) 2020 guidelines. A total of 27 reports were included in this systematic review.

RESULTS

Testing patients with a significant gastrointestinal surgical history, hypogammaglobulinemia, inflammatory bowel disease, intensive care unit, and immunocompromised patients for CDI is highly recommended. Diarrhea in these subsets of patients requires correlation of clinical context and an understanding of assay results to avoid over- and under-treating.

CONCLUSION

CDI should be considered in all patients with traditional risk factors. Heightened clinical suspicion of CDI is required in patients with hypogammaglobulinemia, transplant recipients, patients with gastrointestinal surgical history, and inflammatory bowel disease. Testing should be limited to patients with clinical manifestations of CDI to ensure a high pretest probability for test interpretation. Healthcare workers should adhere to testing algorithms to optimize yield in the appropriate clinical context. Diagnostic assays should follow a sequential, stepwise approach to categorize the toxin expression status of the bacteria accurately.

Clostridioides difficile infection in infants: a case report and literature review

BACKGROUND

Clostridioides difficile (C. difficile) is the major pathogen causing antibiotic-associated diarrhea. There are a variety of symptoms associated with C. difficile infection (CDI) in adults, including self-limiting diarrhea, pseudomembranous colitis, toxic megacolon, septic shock, and even death from the infection. However, the infant's intestine appears to be completely resistant to the effects of C. difficile toxins A and B with rare development of clinical symptoms.

CASE PRESENTATION

In this study, we reported a 1-month-old girl with CDI who was born with neonatal hypoglycemia and necrotizing enterocolitis. Her symptom of diarrhea occurred after extensive use of broad-spectrum antibiotics during hospitalization and was accompanied by elevated white blood cell, platelet, and C-reactive protein levels, and repeated routine stool examinations were abnormal. She was recovered by norvancomycin (an analogue of vancomycin) and probiotic treatment. The results of 16 S rRNA gene sequencing also demonstrated the recovery of intestinal microbiota with the enrichment of Firmicutes and Lactobacillus.

CONCLUSIONS

Based on the literature review and this case report, clinicians should also pay attention to diarrhea caused by C. difficile in infants and young children. More strong evidence is needed to explain the true prevalence of CDI in this population and to better understand the C. difficile-associated diarrhea in infants.

Peroxisome proliferator-activated receptor-γ as the gatekeeper of tight junction in Clostridioides difficile infection

Clostridioides difficile is a major causative pathogen of nosocomial antibiotic-associated diarrhea and severe colitis. Despite the use of vancomycin and fidaxomicin as standard drugs for the treatment of C. difficile infection (CDI), clinical relapse rates remain high. Therefore, new alternative therapeutics to treat CDI are urgently required. The nuclear receptor, peroxisome proliferator-activated receptor-γ (PPAR-γ), is mainly expressed in the adipose tissue and modulates lipid metabolism and insulin sensitization. Previous studies have shown that PPAR-γ is highly expressed in colonic tissues and regulates tight junction function in epithelial cells. However, the role of PPAR-γ in CDI pathogenesis remains unclear. In this study, we used a mouse model of CDI and found that both expression levels of PPAR-γ and the tight junction protein, occludin, were decreased in colonic tissues. Furthermore, to investigate the role of PPAR-γ in CDI, we used PPAR-γ defective mice and found that intestinal permeability and bacterial dissemination in these mice were significantly higher than those in wild-type mice during CDI. Administration of the PPAR-γ agonist, pioglitazone, to activate PPAR-γ activity improved the phenotypes of CDI, including bodyweight loss, inflammation, and intestinal integrity. Taken together, these results demonstrate that PPAR-γ is a potential therapeutic target in CDI, as it modulates colonic inflammation and integrity.

Surface layer protein A from hypervirulent Clostridioides difficile ribotypes induce significant changes in the gene expression of tight junctions and inflammatory response in human intestinal epithelial cells

Background

Surface layer protein A (SlpA), the primary outermost structure of Clostridioides difficile, plays an essential role in C. difficile pathogenesis, although its interaction with host intestinal cells are yet to be understood. The aim of this study was to investigate the effects of SlpA extracted from C. difficile on tight junction (TJ) proteins expression and induction of pro-inflammatory cytokines in human colon carcinoma cell line HT-29. SlpA was extracted from three toxigenic C. difficile clinical strains including RT126, RT001, RT084 as well as C. difficile ATCC 700057 as non-toxigenic strain. Cell viability was performed by MTT assay, and the mRNA expression of TJ proteins and inflammation-associated genes was determined using quantitative RT-PCR. Additionally, the secretion of IL-8, IL-1β and TNF-α cytokines was measured by ELISA.

Results

C. difficile SlpA from selected RTs variably downregulated the expression level of TJs-assassinated genes and increased the expression level of TLR-4 and pro-inflammatory cytokines in HT-29 treated cells. SlpA from RT126 significantly (p_adj<0.05) decreased the gene expression level of claudins family and JAM-A and increased the secretion of IL-8, TNF-α and IL1-β as compared to untreated cells. Moreover, only SlpA from RT001 could significantly induce the expression of IL-6 (p_adj<0.05).

Conclusion

The results of the present study highlighted the importance of SlpA in the pathogenesis of CDI and C. difficile-induced inflammatory response in the gut. Further studies are required to unravel the significance of the observed results in promoting the intestinal inflammation and immune response induced by C. difficile SlpA from different RTs.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12866-022-02665-0.

A patent review on pharmaceutical and therapeutic applications of oxadiazole derivatives for the treatment of chronic diseases (2013-2021)

INTRODUCTION

Oxadiazole is a unique class of heterocycle, possessing numerous important biomedical and therapeutic applications such as anti-bacterial, anti-cancer, anti-inflammatory, inhibitors for diverse enzymes, receptors modulators, and neuroprotective properties. The rapid development in the field of oxadiazole-containing structures is confirmed by the development of numerous clinical drugs such as doxazosin, nesapidil, pleconaril, fasiplon, ataluren, zibotentan, and prenoxdiazine as selected examples.

AREAS COVERED

This review provides a comprehensive overview of the range of biological applications of oxadiazole-containing drugs in a range of patents from 2013 to 2021. The information was collected from available data sources including SciFinder, Reaxys, MedLine, and Chemical Abstracts.

EXPERT OPINION

Oxadiazole is an established class of compounds with fascinating biological properties. The importance of oxadiazoles can be recognized by their enormous application in a wide spectrum of medicinal chemistry from anticancer, antibiotic, and antidiabetic to the use in agriculture and neuroprotection. For instance, the oxadiazole-based compounds have shown the ability to modulate a variety of receptors including the M4 receptor agonists, S1P1 receptor modulators, SSTR5 antagonists, orexin type-2 receptor agonists, liver X receptor agonists, and many more. This testifies to the special features associated with the oxadiazole scaffold making it a significant pharmacophore.

Sex Difference of Effect of Sophora flavescens on Gut Microbiota in Rats

Objective

By observing the sex difference of the gut microbiota in rats and the influence of Sophora flavescens (S. flavescens) on the gut microbiota in rats of different genders, it is hoped that it can provide reference materials for the rational use of S. flavescens in clinical practice.

Method

Taking samples of the jejunum (containing intestinal contents) and feces of 8-week-old rats, and detecting the composition of gut microbiota of females and males by 16S rRNA sequencing technology; At the same time, 8-week-old rats were gavaged with different doses of S. flavescens decoction, and the duodenum, jejunum, ileum, and colon (including the intestinal contents) samples were collected at 1, 2, and 3 weeks, using polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE) technology and real-time fluorescent quantitative PCR (qRT-PCR) technology to observe the changes in the structure and the quantitative changes of 4 major intestinal dominant bacteria Enterococcus, Bacteriodes, Lactobacillus, and Clostridium in each intestinal segment, respectively.

Result

(1) The gut microbiota of normal rats without administration also had obvious gender differences; (2) S. flavescens significantly affects the composition of gut microbiota, and in different intestinal segments, this effect was different between genders under different dosages and different continuous administration times.

Conclusion

The effect of S. flavescens on the gut microbiota of rats had gender differences.

Molecular characterization of pathogenicity locus (PaLoc) and tcdC genetic diversity among tcdA+B+Clostridioides difficile clinical isolates in Tehran, Iran

Clostridioides difficile is the main cause of healthcare-associated diarrhea worldwide. It is proposed that certain C. difficile toxinotypes with distinct pathogenicity locus (PaLoc) variants are associated with disease severity and outcomes. Additionally, few studies have described the common C. difficile toxinotypes, and also little is known about the tcdC variants in Iranian isolates. We characterized the toxinotypes and the tcdC genotypes from a collection of Iranian clinical C. difficile tcdA⁺B⁺ isolates with known ribotypes (RTs). Fifty C. difficile isolates with known RTs and carrying the tcdA and tcdB toxin genes were analyzed. Toxinotyping was carried out based on a PCR-RFLP analysis of a 19.6 kb region encompassing the PaLoc. Genetic diversity of the tcdC gene was determined by the sequencing of the gene. Of the 50 C. difficile isolates investigated, five distinct toxinotypes were recognized. Toxinotypes 0 (33/50, 66%) and V (11/50, 22%) were the most frequently found. C. difficile isolates of the toxinotype 0 mostly belonged to RT 001 (12/33, 36.4%), whereas toxinotype V consisted of RT 126 (9/11, 81.8%). The tcdC sequencing showed six variants (35/50, 70%); tcdC-sc3 (24%), tcdC-A (22%), tcdC-sc9 (18%), tcdC-B (2%), tcdC-sc14 (2%), and tcdC-sc15 (2%). The remaining isolates were wild-types (15/50, 30%) in the tcdC gene. The present study demonstrates that the majority of clinical tcdA⁺B⁺ isolates of C. difficile frequently harbor tcdC genetic variants. We also found that the RT 001/toxinotype 0 and the RT 126/toxinotype V are the most common types among Iranian isolates. Further studies are needed to investigate the putative association of various tcdC genotypes with CDI severity and its recurrence.