Clostridioides difficile: diagnosis and treatments

Microbiota insights into pet ownership and human health

The relationship between pet and owner has already been studied in several studies. Reviewing and summarizing studies on human and pet microbiota and their effects due to keeping pets is the purpose of the current study. Microbiota of the gut, oral cavity, and skin are unique to each individual, and this is also true of their pets (cats and dogs). Microbiota homeostasis is essential for the health of pets and their owners. Dysbiosis or imbalances in the microbiota can increase the risk of disorder progressions such as IBD or Clostridium difficile infections, among others. The microbial communities of humans change as a result of various factors, such as keeping pets. Pet owners frequently contact domestic dogs and cats, which affects their microbiota. As a result of keeping pets, the microbiota of different areas of the human body has changed, which has been associated with a decrease in pathogenic bacteria and an increase in beneficial bacteria.

Exploring Advanced Therapies for Primary Biliary Cholangitis: Insights from the Gut Microbiota-Bile Acid-Immunity Network

Primary biliary cholangitis (PBC) is a cholestatic liver disease characterized by immune-mediated injury to small bile ducts. Although PBC is an autoimmune disease, the effectiveness of conventional immunosuppressive therapy is disappointing. Nearly 40% of PBC patients do not respond to the first-line drug UDCA. Without appropriate intervention, PBC patients eventually progress to liver cirrhosis and even death. There is an urgent need to develop new therapies. The gut-liver axis emphasizes the interconnection between the gut and the liver, and evidence is increasing that gut microbiota and bile acids play an important role in the pathogenesis of cholestatic diseases. Dysbiosis of gut microbiota, imbalance of bile acids, and immune-mediated bile duct injury constitute the triad of pathophysiology in PBC. Autoimmune cholangitis has the potential to be improved through immune system modulation. Considering the failure of conventional immunotherapies and the involvement of gut microbiota and bile acids in the pathogenesis, targeting immune factors associated with them, such as bile acid receptors, microbial-derived molecules, and related specific immune cells, may offer breakthroughs. Understanding the gut microbiota-bile acid network and related immune dysfunctions in PBC provides a new perspective on therapeutic strategies. Therefore, we summarize the latest advances in research of gut microbiota and bile acids in PBC and, for the first time, explore the possibility of related immune factors as novel immunotherapy targets. This article discusses potential therapeutic approaches focusing on regulating gut microbiota, maintaining bile acid homeostasis, their interactions, and related immune factors.

The Role of Probiotics in the Prevention of Clostridioides difficile Infection in Patients with Chronic Kidney Disease

In patients suffering from chronic kidney disease (CKD), substantial unfavourable alterations in the intestinal microbiota composition, i.e., dysbiosis, have been noted. The main causes of such dysbiosis among others are insufficient dietary fibre content in the diet, fluid restrictions, medications used, and physical activity limitation. One clinically important consequence of dysbiosis in CKD patients is high risk of Clostridioides difficile infection (CDI). In observational studies, it was found that CDI is more frequent in CKD patients than in the general population. This appears to be related to high hospitalization rate and more often antibiotic therapy use, leading up to the occurrence of dysbiosis. Therefore, the use of probiotics in CKD patients may avert changes in the intestinal microbiota, which is the major risk factor of CDI. The aim of this review paper is to summarize the actual knowledge concerning the use of probiotics in CDI prevention in CKD patients in the context of CDI prevention in the general population.

The role of gut microbiota in intestinal disease: from an oxidative stress perspective

Recent studies have indicated that gut microbiota-mediated oxidative stress is significantly associated with intestinal diseases such as colorectal cancer, ulcerative colitis, and Crohn's disease. The level of reactive oxygen species (ROS) has been reported to increase when the gut microbiota is dysregulated, especially when several gut bacterial metabolites are present. Although healthy gut microbiota plays a vital role in defending against excessive oxidative stress, intestinal disease is significantly influenced by excessive ROS, and this process is controlled by gut microbiota-mediated immunological responses, DNA damage, and intestinal inflammation. In this review, we discuss the relationship between gut microbiota and intestinal disease from an oxidative stress perspective. In addition, we also provide a summary of the most recent therapeutic approaches for preventing or treating intestinal diseases by modifying gut microbiota.

A Randomized, Double-Blind, Phase 3 Safety and Efficacy Study of Ridinilazole Versus Vancomycin for Treatment of Clostridioides difficile Infection: Clinical Outcomes With Microbiome and Metabolome Correlates of Response

BACKGROUND

Exposure to antibiotics predisposes to dysbiosis and Clostridioides difficile infection (CDI) that can be severe, recurrent (rCDI), and life-threatening. Nonselective drugs that treat CDI and perpetuate dysbiosis are associated with rCDI, in part due to loss of microbiome-derived secondary bile acid (SBA) production. Ridinilazole is a highly selective drug designed to treat CDI and prevent rCDI.

METHODS

In this phase 3 superiority trial, adults with CDI, confirmed with a stool toxin test, were randomized to receive 10 days of ridinilazole (200 mg twice daily) or vancomycin (125 mg 4 times daily). The primary endpoint was sustained clinical response (SCR), defined as clinical response and no rCDI through 30 days after end of treatment. Secondary endpoints included rCDI and change in relative abundance of SBAs.

RESULTS

Ridinilazole and vancomycin achieved an SCR rate of 73% versus 70.7%, respectively, a treatment difference of 2.2% (95% CI: -4.2%, 8.6%). Ridinilazole resulted in a 53% reduction in recurrence compared with vancomycin (8.1% vs 17.3%; 95% CI: -14.1%, -4.5%; P = .0002). Subgroup analyses revealed consistent ridinilazole benefit for reduction in rCDI across subgroups. Ridinilazole preserved microbiota diversity, increased SBAs, and did not increase the resistome. Conversely, vancomycin worsened CDI-associated dysbiosis, decreased SBAs, increased Proteobacteria abundance (∼3.5-fold), and increased the resistome.

CONCLUSIONS

Although ridinilazole did not meet superiority in SCR, ridinilazole greatly reduced rCDI and preserved microbiome diversity and SBAs compared with vancomycin. These findings suggest that treatment of CDI with ridinilazole results in an earlier recovery of gut microbiome health. Clinical Trials Registration.Ri-CoDIFy 1 and 2: NCT03595553 and NCT03595566.

Potentiation and Mechanism of Berberine as an Antibiotic Adjuvant Against Multidrug-Resistant Bacteria

The growing global apprehension towards multi-drug resistant (MDR) bacteria necessitates the development of innovative strategies to combat these infections. Berberine (BER), an isoquinoline quaternary alkaloid derived from various medicinal plants, has surfaced as a promising antibiotic adjuvant due to its ability to enhance the effectiveness of conventional antibiotics against drug-resistant bacterial strains. Here, we overview the augmenting properties and mechanisms of BER as an adjunctive antibiotic against MDR bacteria. BER has been observed to exhibit synergistic effects when co-administered with a range of antibiotics, including β-lactams, quinolones, aminoglycosides, tetracyclines, macrolides, lincosamides and fusidic acid. The adjunctive properties of BER led to an increase in antimicrobial effectiveness for these antibiotics against the corresponding bacteria, a decrease in minimal inhibitory concentrations, and even the reversal from resistance to susceptibility sometimes. The potential mechanisms responsible for these effects included the inhibition of antibiotic efflux, the disruption of biofilm formation, the modulation of host immune responses, and the restoration of gut microbiota homeostasis. In brief, BER demonstrated significant potential as an antibiotic adjuvant against MDR bacteria and is a promising candidate for combination therapy. Further research is necessary to fully elucidate its mechanism of action and address the challenges associated with its clinical application.

Biogeographic distribution and molecular epidemiology of Clostridioides (Clostridium) difficile in Western Australian soils

Clostridioides (Clostridium) difficile is a leading cause of infectious diarrhea in humans and production animals and can be found in a variety of environmental sources. The prevalence and diversity of multi-locus sequence type clade 5 strains of C. difficile in Australian production animals suggest Australia might be the ancestral home of this lineage of One Health importance. To better understand the role of the environment in the colonization of humans and animals in Australia, it is important to investigate these endemic sources. This study describes the prevalence, molecular epidemiology, and biogeographic distribution of C. difficile in soils of Western Australia. A total of 321 soil samples from remote geographical locations across the eight health regions of Western Australia were screened for C. difficile and isolates characterized by PCR ribotyping and toxin gene profiling. C. difficile was isolated from 31.15% of samples, with the highest prevalence in the Perth Metropolitan Health Region (49.25%, n = 33/67). Overall, 52 different strains [PCR ribotypes (RTs)] were identified, with 14 being novel, and 38% (38/100) of isolates being toxigenic, the most common of which was RT014/020. Five unique novel isolates showed characteristics similar to C. difficile clade 5. This is the first study of C. difficile isolated from soils in Australia. The high prevalence and heterogeneity of C. difficile strains recovered suggest that soils play a role in the survival and environmental dissemination of this organism, and potentially its transmission among native wildlife and production animals, and in community and hospital settings.IMPORTANCEClostridium difficile is a pathogen of One Health importance. To better understand the role of the environment in human and animal colonization/infection, it is critical that autochthonous reservoirs/sources of C. difficile be investigated. This is the first study of C. difficile isolated from soils of Western Australia (WA). Here, the ecology of C. difficile in WA is described by examining the geographic distribution, molecular epidemiology, and diversity of C. difficile isolated from soils across WA.

Therapeutic Approach Targeting Gut Microbiome in Gastrointestinal Infectious Diseases

While emerging evidence highlights the significance of gut microbiome in gastrointestinal infectious diseases, treatments like Fecal Microbiota Transplantation (FMT) and probiotics are gaining popularity, especially for diarrhea patients. However, the specific role of the gut microbiome in different gastrointestinal infectious diseases remains uncertain. There is no consensus on whether gut modulation therapy is universally effective for all such infections. In this comprehensive review, we examine recent developments of the gut microbiome's involvement in several gastrointestinal infectious diseases, including infection of Helicobacter pylori, Clostridium difficile, Vibrio cholerae, enteric viruses, Salmonella enterica serovar Typhimurium, Pseudomonas aeruginosa Staphylococcus aureus, Candida albicans, and Giardia duodenalis. We have also incorporated information about fungi and engineered bacteria in gastrointestinal infectious diseases, aiming for a more comprehensive overview of the role of the gut microbiome. This review will provide insights into the pathogenic mechanisms of the gut microbiome while exploring the microbiome's potential in the prevention, diagnosis, prediction, and treatment of gastrointestinal infections.

Does this patient have C. difficile infection? A systematic review and meta-analysis

BACKGROUND

The clinical features and predictors of Clostridioides difficile infection overlap with many conditions.

OBJECTIVES

We performed a systematic review to evaluate the diagnostic utility of clinical features (clinical examination, risk factors, laboratory tests, radiographic findings) associated with C. difficile.

METHODS

Data Sources: MEDLINE, EMBASE, CINAHL, and Cochrane databases were searched up to September 2021.

STUDY ELIGIBILITY CRITERIA

Studies that reported clinical features of C. difficile, a valid reference standard test for confirming diagnosis of C. difficile, and a comparison among patients with a positive and negative test result.

PARTICIPANTS

Adult and pediatric patients across diverse clinical settings.

OUTCOMES

Sensitivity, specificity, likelihood ratios.

REFERENCE STANDARD

Stool nucleic acid amplification tests, enzyme immunoassays, cell cytotoxicity assay, and stool toxigenic culture. Assessment of Risk of Bias: Rational Clinical Examination Series and QUADAS-2. Methods of Data Synthesis: Univariate and bivariate analyses.

RESULTS

We screened 11,231 articles of which 40 were included, enabling evaluation of 66 features for their diagnostic utility for C. difficile (10 clinical examination findings, 4 laboratory tests, 10 radiographic findings, prior exposure to 13 antibiotic types, and 29 clinical risk factors). Of the ten features identified on clinical examination, none were significantly clinically associated with increased likelihood of C. difficile infection. Some features that increased likelihood of C. difficile infection were stool leukocytes (LR+ 5.31, 95% CI 3.29-8.56) and hospital admission in prior three months (LR+ 2.14, 95% CI 1.48-3.11). Several radiographic findings also strongly increased the likelihood of C. difficile infection like ascites (LR+ 2.91, 95% CI 1.89-4.49).

DISCUSSION

There is limited utility of bedside clinical examination alone in detecting C. difficile infection. Accurate diagnosis of C. difficile infection requires thoughtful clinical assessment for interpretation of microbiologic testing in all suspected cases.

The cell wall lipoprotein CD1687 acts as a DNA binding protein during deoxycholate-induced biofilm formation in Clostridioides difficile

The ability of bacterial pathogens to establish recurrent and persistent infections is frequently associated with their ability to form biofilms. Clostridioides difficile infections have a high rate of recurrence and relapses and it is hypothesized that biofilms are involved in its pathogenicity and persistence. Biofilm formation by C. difficile is still poorly understood. It has been shown that specific molecules such as deoxycholate (DCA) or metronidazole induce biofilm formation, but the mechanisms involved remain elusive. In this study, we describe the role of the C. difficile lipoprotein CD1687 during DCA-induced biofilm formation. We showed that the expression of CD1687, which is part of an operon within the CD1685-CD1689 gene cluster, is controlled by multiple transcription starting sites and some are induced in response to DCA. Only CD1687 is required for biofilm formation and the overexpression of CD1687 is sufficient to induce biofilm formation. Using RNAseq analysis, we showed that CD1687 affects the expression of transporters and metabolic pathways and we identified several potential binding partners by pull-down assay, including transport-associated extracellular proteins. We then demonstrated that CD1687 is surface exposed in C. difficile, and that this localization is required for DCA-induced biofilm formation. Given this localization and the fact that C. difficile forms eDNA-rich biofilms, we confirmed that CD1687 binds DNA in a non-specific manner. We thus hypothesize that CD1687 is a component of the downstream response to DCA leading to biofilm formation by promoting interaction between the cells and the biofilm matrix by binding eDNA.

Coexisting cytomegalovirus colitis in an immunocompetent patient with Clostridioides difficile colitis: A case report

BACKGROUND

Clostridioides difficile (C. difficile) colitis is one of the most common infections in hospitalized patients, characterized by fever and diarrhea. It usually improves after appropriate antibiotic treatment; if not, comorbidities should be considered. Cytomegalovirus (CMV) colitis is a possible co-existing diagnosis in patients with C. difficile infection with poor treatment response. However, compared with immunocompromised patients, CMV colitis in immunocompetent patients is not well studied.

CASE SUMMARY

We present an unusual case of co-existing CMV colitis in an immunocompetent patient with C. difficile infection. An 80-year-old female patient was referred to the infectious disease department due to diarrhea, abdominal discomfort, and fever for 1 wk during her hospitalization for surgery. C. difficile toxin B polymerase chain reaction on stool samples was positive. After C. difficile infection was diagnosed, oral vancomycin treatment was administered. Her symptoms including diarrhea, fever and abdominal discomfort improved for ten days. Unfortunately, the symptoms worsened again with bloody diarrhea and fever. Therefore, a sigmoidoscopy was performed for evaluation, showing a longitudinal ulcer on the sigmoid colon. Endoscopic biopsy confirmed CMV colitis, and the clinical symptoms improved after using ganciclovir.

CONCLUSION

Co-existing CMV colitis should be considered in patients with aggravated C. difficile infection on appropriate treatment, even in immunocompetent hosts.

Genomic epidemiology and transmission dynamics of recurrent Clostridioides difficile infection in Western Australia

Recurrent cases of Clostridioides difficile infection (rCDI) remain one of the most common and serious challenges faced in the management of CDI. The accurate distinction between a relapse (caused by infection with the same strain) and reinfection (caused by a new strain) has implications for infection control and prevention, and patient therapy. Here, we used whole-genome sequencing to investigate the epidemiology of 94 C. difficile isolates from 38 patients with rCDI in Western Australia. The C. difficile strain population comprised 13 sequence types (STs) led by ST2 (PCR ribotype (RT) 014, 36.2%), ST8 (RT002, 19.1%) and ST34 (RT056, 11.7%). Among 38 patients, core genome SNP (cgSNP) typing found 27 strains (71%) from initial and recurring cases differed by ≤ 2 cgSNPs, suggesting a likely relapse of infection with the initial strain, while eight strains differed by ≥ 3 cgSNPs, suggesting reinfection. Almost half of patients with CDI relapse confirmed by WGS suffered episodes that occurred outside the widely used 8-week cut-off for defining rCDI. Several putative strain transmission events between epidemiologically unrelated patients were identified. Isolates of STs 2 and 34 from rCDI cases and environmental sources shared a recent evolutionary history, suggesting a possible common community reservoir. For some rCDI episodes caused by STs 2 and 231, within-host strain diversity was observed, characterised by loss/gain of moxifloxacin resistance. Genomics improves discrimination of relapse from reinfection and identifies putative strain transmission events among patients with rCDI. Current definitions of relapse and reinfection based on the timing of recurrence need to be reconsidered.

Faecal microbiota transplantation for recurrent C. difficile infections: challenges and improvement opportunities for clinical practice and healthcare systems

BACKGROUND

There is growing interest in faecal microbiota transplantation (FMT) as a treatment for recurrent Clostridioides difficile infection (CDI), but evidence on the diverse requirements for safe, effective and accessible services is fragmented and limited.

AIMS

To identify key components of FMT provision relating to the patient care pathway, stool donor pathway and wider healthcare system, and to explore variation in practice METHODS: We conducted a narrative review of the literature and consultations with key clinical experts in the field. Evidence is drawn from high-income country contexts, with an emphasis on Australia, Canada, Italy and the United Kingdom as case example countries.

RESULTS

We identify and discuss key challenges to do with healthcare capacity (workforce, FMT and stool banking facilities), donors and donations, patient access and choice of FMT delivery routes, regulation, costs and reimbursement. We also identify improvement opportunities to increase awareness of FMT and referral processes, physician training, maintaining patient registries and outcome monitoring metrics, in-country regulatory harmonisation and tackling reimbursement challenges and discuss future research needs.

CONCLUSION

Effectively bringing FMT to patients in a healthcare system requires much more than just the existence of a clinically effective procedure. With FMT being a potentially effective treatment option for recurrent CDI for many patients, a well-rounded understanding of how appropriate FMT capacity can be built and nurtured is important for both healthcare providers and policymakers seeking to improve patient care.

Clostridioides difficile S-Layer Protein A (SlpA) Serves as a General Phage Receptor

Therapeutic bacteriophages (phages) are being considered as alternatives in the fight against Clostridioides difficile infections. To be efficient, phages should have a wide host range, buthe lack of knowledge about the cell receptor used by C. difficile phages hampers the rational design of phage cocktails. Recent reports suggested that the C. difficile surface layer protein A (SlpA) is an important phage receptor, but available data are still limited. Here, using the epidemic R20291 strain and its FM2.5 mutant derivative lacking a functional S-layer, we show that the absence of SlpA renders cells completely resistant to infection by ϕCD38-2, ϕCD111, and ϕCD146, which normally infect the parental strain. Complementation with 12 different S-layer cassette types (SLCTs) expressed from a plasmid revealed that SLCT-6 also allowed infection by ϕCD111 and SLCT-11 enabled infection by ϕCD38-2 and ϕCD146. Of note, the expression of SLCT-1, -6, -8, -9, -10, or -12 conferred susceptibility to infection by 5 myophages that normally do not infect the R20291 strain. Also, deletion of the D2 domain within the low-molecular-weight fragment of SlpA was found to abolish infection by ϕCD38-2 and ϕCD146 but not ϕCD111. Altogether, our data suggest that many phages use SlpA as their receptor and, most importantly, that both siphophages and myophages target SlpA despite major differences in their tail structures. Our study therefore represents an important step in understanding the interactions between C. difficile and its phages. IMPORTANCE Phage therapy represents an interesting alternative to treat Clostridioides difficile infections because, contrary to antibiotics, most phages are highly species specific, thereby sparing the beneficial gut microbes that protect from infection. However, currently available phages against C. difficile have a narrow host range and target members from only one or a few PCR ribotypes. Without a clear comprehension of the factors that define host specificity, and in particular the host receptor recognized by phages, it is hard to develop therapeutic cocktails in a rational manner. In our study, we provide clear and unambiguous experimental evidence that SlpA is a common receptor used by many siphophages and myophages. Although work is still needed to define how a particular phage receptor-binding protein binds to a specific SLCT, the identification of SlpA as a common receptor is a major keystone that will facilitate the rational design of therapeutic phage cocktails against clinically important strains.

A rapid multiplex real-time PCR detection of toxigenic Clostridioides difficile directly from fecal samples

This study developed a new single-tube multiplex real-time PCR method for detecting toxigenic C. difficile directly from fecal samples using tcdA, tcdB, cdtB, and internal gene tpi as targets, which could be performed on kinds of polymerase chain reaction device including point-of-care testing (POCT), with improved detection efficiency. The specificity, sensitivity, and repeatability of each gene was evaluated using 69 C. difficile isolates and 74 fecal samples. Results were compared with established PCR, qPCR, and ELISA methods. Interspecies specificity was 100% based on six common intestinal pathogens (Escherichia coli, Enterococcus Faecium, Enterococcus faecalis, Clostridium perfringens, Bacteroides fragilis, Clostridium botulinum). The lower detection limit (LDL) for tcdA, tcdB, and cdtB with pure C. difficile DNA was 10¹,10⁰, and 10⁰ copies/μL, respectively, the coefficients of variation among different experimental batches and within each experimental batch were both less than 3%, which shows that this method has strong repeatability. And the LDL of fecal DNA was 5 × 10⁰, 5 × 10³, and 5 × 10² colony-forming units (CFU)/g, respectively. In addition, the efficiency for detection of tcdA was compared with established PCR and real-time PCR methods, demonstrating high consistency (98.4%) and similar sensitivity. ELISA was used to confirm inconsistent results, which were identical with our method. The sensitivity and specificity for detecting toxigenic C. difficile in fecal samples were 96.49% and 94.12% compared with the toxigenic culture (TC). This method effectively identified the toxigenic and non-toxigenic strains with high specificity, sensitivity, and repeatability, and could reduce the false positive rate of tcdA, and accurately identify the typical Asian strain RT017, making it potentially contribute to the surveillance of CDI in China.

Supplementary Information

The online version contains supplementary material available at 10.1007/s13205-022-03434-6.

Improving care for patients with Clostridioides difficile infection: A clinical practice and healthcare systems perspective

Introduction

Arriving at a C. difficile infection (CDI) diagnosis, treating patients and dealing with recurrences is not straightforward, but a comprehensive and well-rounded understanding of what is needed to improve patient care is lacking. This manuscript addresses the paucity of multidisciplinary perspectives that consider clinical practice related and healthcare system-related challenges to optimizing care delivery.

Methods

We draw on narrative review, consultations with clinical experts and patient representatives, and a survey of 95 clinical and microbiology experts from the UK, France, Italy, Australia and Canada, adding novel multi-method evidence to the knowledge base.

Results and discussion

We examine the patient pathway and variations in clinical practice and identify, synthesize insights on and discuss associated challenges. Examples of key challenges include the need to conduct multiple tests for a conclusive diagnosis, treatment side-effects, the cost of some antibiotics and barriers to access of fecal microbiota transplantation, difficulties in distinguishing recurrence from new infection, workforce capacity constraints to effective monitoring of patients on treatment and of recurrence, and ascertaining whether a patient has been cured. We also identify key opportunities and priorities for improving patient care that target both clinical practice and the wider healthcare system. While there is some variety across surveyed countries' healthcare systems, there is also strong agreement on some priorities. Key improvement actions seen as priorities by at least half of survey respondents in at least three of the five surveyed countries include: developing innovative products for both preventing (Canada, Australia, UK, Italy, and France) and treating (Canada, Australia, and Italy) recurrences; facilitating more multidisciplinary patient care (UK, Australia, and France); updating diagnosis and treatment guidelines (Australia, Canada, and UK); and educating and supporting professionals in primary care (Italy, UK, Canada, and Australia) and those in secondary care who are not CDI experts (Italy, Australia, and France) on identifying symptoms and managing patients. Finally, we discuss key evidence gaps for a future research agenda.

CDT of Clostridioides difficile Induces MLC-Dependent Intestinal Barrier Dysfunction in HT-29/B6 Epithelial Cell Monolayers

Background: Clostridioides difficile binary toxin (CDT) defines the hypervirulence of strains in nosocomial antibiotic-induced colitis with the highest mortality. The objective of our study was to investigate the impact of CDT on the intestinal epithelial barrier and to enlighten the underlying molecular mechanisms. Methods: Functional measurements of epithelial barrier function by macromolecular permeability and electrophysiology were performed in human intestinal HT-29/B6 cell monolayers. Molecular analysis of the spatial distribution of tight junction protein and cytoskeleton was performed by super-resolution STED microscopy. Results: Sublethal concentrations of CDT-induced barrier dysfunction with decreased TER and increased permeability for 332 Da fluorescein and 4 kDa FITC-dextran. The molecular correlate to the functional barrier defect by CDT was found to be a tight junction protein subcellular redistribution with tricellulin, occludin, and claudin-4 off the tight junction domain. This redistribution was shown to be MLCK-dependent. Conclusions: CDT compromised epithelial barrier function in a human intestinal colonic cell model, even in sublethal concentrations, pointing to barrier dysfunction in the intestine and leak flux induction as a diarrheal mechanism. However, this cannot be attributed to the appearance of apoptosis and necrosis, but rather to an opening of the paracellular leak pathway as the result of epithelial tight junction alterations.

Evaluation of Two Rapid Diagnostic Clostridioides difficile Infection Tests in a Chinese Hospital: A Real-world Analysis

Background: Accurate diagnosis is essential for optimal prevention and treatment of Clostridioides difficile infection (CDI), and various diagnostic methods must be evaluated. Objectives: We aimed to evaluate and compare the performance of VIDAS C. difficile, C. DIFF QUIK CHEK COMPLETE (QCC), and toxigenic culture (TC) tests for diagnosing CDI and further determine the relationships between clinical factors and the toxin status of patients. Methods: Stool samples were randomly selected for VIDAS or QCC testing according to the manufacturer’s instructions between May 2017 and May 2021, and their performance was compared with that of TC. Clinical information was obtained from the hospital’s electronic medical records. Results: Among 10,897 samples tested, 6,435 and 4,462 samples were assigned for VIDAS and QCC tests, respectively. A total of 9.1% (996/10,897) of the samples were positive for TC. The sensitivity, specificity, positive predictive value, and negative predictive value were 36.6%, 98.6%, 72.1%, and 87.6% for VIDAS toxins A and B testing and 31.6%, 98.2%, 64.0%, and 87.8% for QCC toxin testing, respectively. Our results showed that the clinical data of the patients with positive and detectable toxins were not significantly different. Conclusions: The VIDAS and QCC tests provide rapid screening assays for the laboratory diagnosis of CDI. However, a more specific test to detect free toxins is required to confirm the diagnosis for glutamate dehydrogenase (GDH)-positive and toxin-negative samples. The clinical characteristics and outcomes of this cohort were similar, regardless of the results of toxins A and B testing.

Evaluation of Derivatives of (+)-Puupehenone against Clostridioides difficile and Other Gram-Positive Bacteria

Patients receiving healthcare are at higher risk of acquiring healthcare-associated infections, which cause a significant number of illnesses and deaths. Most pathogens responsible for these infections are highly resistant to multiple antibiotics, prompting the need for discovery of new therapeutics to combat these evolved threats. We synthesized structural derivatives of (+)-puupehenone, a marine natural product, and observed growth inhibition of several clinically relevant Gram-positive bacteria, particularly Clostridioides difficile. The most potent compounds-(+)-puupehenone, 1, 15, 19, and 20-all inhibited C. difficile in the range of 2.0-4.0 μg/mL. Additionally, when present in the range of 1-8 μg/mL, a subset of active compounds-(+)-puupehenone, 1, 6, 15, and 20-greatly reduced the ability of C. difficile to produce exotoxins, which are required for disease in infected hosts. Our findings showcase a promising class of compounds for potential drug development against Gram-positive pathogens, such as C. difficile.

Clostridioides difficile Infection in Patients after Organ Transplantation—A Narrative Overview

Clostridioides difficile infection (CDI) is one of the most common causes of antibiotic-associated diarrhea. The pathogenesis of this infection participates in the unstable colonization of the intestines with the physiological microbiota. Solid-organ-transplant (SOT) patients and patients after hematopoietic stem cell transplantation are more prone to CDI compared to the general population. The main CDI risk factors in these patients are immunosuppressive therapy and frequent antibiotic use leading to dysbiosis. The current review article provides information about the risk factors, incidence and course of CDI in patients after liver, kidney, heart and lung transplantation and hematopoietic stem cell transplantation.

Fecal microbiota transplantation: a review on current formulations in Clostridioides difficile infection and future outlooks

INTRODUCTION

The role of the gut microbiota in health and the pathogenesis of several diseases has been highlighted in recent years. Even though the precise mechanisms involving the microbiome in these ailments are still unclear, microbiota-modulating therapies have been developed. Fecal microbiota transplantation (FMT) has shown significant results against Clostridioides difficile infection (CDI), and its potential has been investigated for other diseases. Unfortunately, the technical aspects of the treatment make it difficult to implement. Pharmaceutical technology approaches to encapsulate microorganisms could play an important role in providing this treatment and render the treatment modalities easier to handle.

AREAS COVERED

After an overview of CDI, this narrative review aims to discuss the current formulations for FMT and specifically addresses the technical aspects of the treatment. This review also distinguishes itself by focusing on the hurdles and emphasizing the possible improvements using pharmaceutical technologies.

EXPERT OPINION

FMT is an efficient treatment for recurrent CDI. However, its standardization is overlooked. The approach of industrial and hospital preparations of FMT are different, but both show promise in their respective methodologies. Novel FMT formulations could enable further research on dysbiotic diseases in the future.

Presence of Clostridioides difficile in cattle feces, carcasses, and slaughterhouses: Molecular characterization and antibacterial susceptibility of the recovered isolates

The aims of this study were to isolate and identify Clostridioides difficile from cattle feces and carcasses, and slaughterhouse samples, and to determine the molecular characteristics and antibacterial susceptibility of the recovered isolates. A total of 220 samples, including 100 cattle fecal samples, 100 cattle carcass surface samples, and 20 slaughterhouse samples were used as the study material. In total, 12 (5.45%) samples, including 11 (11%) cattle fecal samples and 1 (5%) slaughterhouse sample, were found to be positive for C. difficile. On the other hand, all of the carcass samples were negative for C. difficile. A total of 11 (91.66%) isolates, including 10 fecal isolates and 1 slaughterhouse wastewater isolate, were found to be positive for the presence of the toxin genes tcdA and tcdB, whilst 1 fecal isolate was found to be negative for both genes. In addition, 3 different ERIC-PCR profiles were identified in the 11 fecal isolates. The ERIC-PCR profile of the slaughterhouse wastewater isolate was found to be similar to one of the ERIC-PCR profiles obtained from the fecal isolates. All of the isolates were resistant to ciprofloxacin and levofloxacin. Considering that the agent is a spore-forming bacterium shed in feces, the detection of C. difficile isolates of different genotypes, some carrying toxin genes, suggests that feces and slaughterhouse wastewater carrying this bacterium may pose a risk for the contamination of carcasses. The current study revealed that hygiene conditions should be performed to the maximum extent in slaughterhouses.

Cellular adaptation of Clostridioides difficile to high salinity encompasses a compatible solute-responsive change in cell morphology

Infections by the pathogenic gut bacterium Clostridioides difficile cause severe diarrheas up to a toxic megacolon and are currently among the major causes of lethal bacterial infections. Successful bacterial propagation in the gut is strongly associated with the adaptation to changing nutrition-caused environmental conditions; e.g. environmental salt stresses. Concentrations of 350 mM NaCl, the prevailing salinity in the colon, led to significantly reduced growth of C. difficile. Metabolomics of salt- stressed bacteria revealed a major reduction of the central energy generation pathways, including the Stickland-fermentation reactions. No obvious synthesis of compatible solutes was observed up to 24 h of growth. The ensuing limited tolerance to high salinity and absence of compatible solute synthesis might result from an evolutionary adaptation to the exclusive life of C. difficile in the mammalian gut. Addition of the compatible solutes carnitine, glycine-betaine, γ-butyrobetaine, crotonobetaine, homobetaine, proline-betaine and dimethylsulfoniopropionate (DMSP) restored growth (choline and proline failed) under conditions of high salinity. A bioinformatically-identified OpuF-type ABC-transporter imported most of the used compatible solutes. A long-term adaptation after 48 h included a shift of the Stickland fermentation-based energy metabolism from the utilization to the accumulation of L-proline and resulted in restored growth. Surprisingly, salt stress resulted in the formation of coccoid C. difficile cells instead of the typical rod-shaped cells, a process reverted by the addition of several compatible solutes. Hence, compatible solute import via OpuF is the major immediate adaptation strategy of C. difficile to high salinity-incurred cellular stress. This article is protected by copyright. All rights reserved.

Oral Vancomycin Prophylaxis for Primary and Secondary Prevention of Clostridioides difficile Infection in Patients Treated with Systemic Antibiotic Therapy: A Systematic Review, Meta-Analysis and Trial Sequential Analysis

Background: Clostridioides difficile infection (CDI) is associated with substantial morbidity and mortality as well as high propensity of recurrence. Systemic antibiotic therapy (SAT) represents the top inciting factor of CDI, both primary and recurrent (rCDI). Among the many strategies aimed to prevent CDI in high-risk subjects undergoing SAT, oral vancomycin prophylaxis (OVP) appears promising under a cost-effectiveness perspective. Methods: A systematic review with meta-analysis and trial sequential analysis (TSA) of studies assessing the efficacy and the safety of OVP to prevent primary CDI and rCDI in persons undergoing SAT was carried out. PubMed and EMBASE were searched until 30 September 2021. The protocol was pre-registered on PROSPERO (CRD42019145543). Results: Eleven studies met the inclusion criteria, only one being a randomized controlled trial (RCT). Overall, 929 subjects received OVP and 2011 represented the comparator group (no active prophylaxis). OVP exerted a strong protective effect for CDI occurrence: odds ratio 0.14, 95% confidence interval 0.04–0.38. Moderate heterogeneity was observed: I² 54%. This effect was confirmed throughout several subgroup analyses, including prevention of primary CDI versus rCDI. TSA results pointed at the conclusive nature of the evidence. Results were robust to a variety of sensitivity and quantitative bias analyses, although the underlying evidence was deemed as low quality. No differences between the two groups were highlighted regarding the onset of vancomycin-resistant Enterococcus infections. Conclusions: OVP appears to be an efficacious option for prevention of CDI in high-risk subjects undergoing SAT. Nevertheless, additional data from RCTs are needed to establish OVP as good clinical practice and define optimal dosage and duration.

Irreversible inhibitors of the proline racemase (PRAC) unveil innovative mechanism of action as antibacterial against Clostridioides difficile

Proline racemases (PRAC), catalyzing the L-proline and D-proline interconversion, are essential factors in eucaryotic pathogenes such as Trypanosoma cruzi, Trypanosoma vivax and Clostridioides difficile. If the discovery of irreversible inhibitors of Trypanosoma cruzi PRAC (TcPRAC) led to innovative therapy of the Chagas disease, no inhibitors of CdPRAC have been discovered to date. However, Clostridioides difficile, due to an increased incidence in recent years, is considered as a major cause of health threat. In this work, we have taken into account the similarity between TcPRAC and CdPRAC enzymes to design new inhibitors of CdPRAC. Starting from (E) 4-oxopent-2-enoic acid TcPRAC irreversible inhibitors, we synthesized 4-aryl substituted analogues and evaluated their CdPRAC enzymatic inhibition against eleven strains of Clostridioides difficile. This study resulted in promising candidates and allowed for identification of (E)-4-(3-bromothiophen-2-yl)-4-oxobut-2-enoic acid 20 that was chosen for complementary in vivo studies and did not reveal in vivo toxicity.

Epidemiology of Clostridioides difficile in South Africa

Background

Clostridioides difficile (CD) is the most common healthcare-associated enteric infection. There is currently limited epidemiological evidence on CD incidence in South Africa.

Aim

To estimate the burden of CD infection (CDI) in the South African public sector between 1 July 2016 and 30 June 2017.

Methods

A retrospective cohort study utilizing secondary data was conducted to describe the epidemiology of CD in South Africa. We assessed the patient-level association between variables of interest, CD, and CD recurrence, by undertaking both univariate and multivariable analysis. Adjusted incidence rate ratios (aIRR) were calculated utilizing multivariable Poisson regression. The incidence of CD, CD recurrence and CD testing was estimated by Poisson regression for various levels of care and provinces.

Results

A total of 14 023 samples were tested for CD during the study period. After applying exclusion criteria, we were left with a sample of 10 053 of which 1 860 (18.50%) tested CD positive. A positive and significant association between CDI and level of care is found, with patients treated in specialized tuberculosis (TB) hospitals having a five-fold increased adjusted incidence risk ratio (aIRR) for CDI (aIRR 4.96 CI95% 4.08–6.04,) compared to those managed in primary care. Patients receiving care at a secondary, tertiary, or central hospital had 35%, 66% and 41% increased adjusted incidence of CDI compared to those managed in primary care, respectively. National incidence of CDI is estimated at 53.89 cases per 100 000 hospitalizations (CI95% 51.58–56.29), the incidence of recurrence at 21.39 (CI95% 15.06–29.48) cases per 1 000 cases and a recurrence rate of 2.14% (CI95% 1.51–2.94).

Conclusion

Compared to European countries, we found a comparable incidence of CD. However, our estimates are lower than those for the United States. Compared to high-income countries, this study found a comparatively lower CD recurrence.

Prediction of in-hospital mortality of Clostriodiodes difficile infection using critical care database: a big data-driven, machine learning approach

RESEARCH OBJECTIVES

Clostriodiodes difficile infection (CDI) is a major cause of healthcare-associated diarrhoea with high mortality. There is a lack of validated predictors for severe outcomes in CDI. The aim of this study is to derive and validate a clinical prediction tool for CDI in-hospital mortality using a large critical care database.

METHODOLOGY

The demographics, clinical parameters, laboratory results and mortality of CDI were extracted from the Medical Information Mart for Intensive Care-III (MIMIC-III) database. We subsequently trained three machine learning models: logistic regression (LR), random forest (RF) and gradient boosting machine (GBM) to predict in-hospital mortality. The individual performances of the models were compared against current severity scores (Clostridiodes difficile Associated Risk of Death Score (CARDS) and ATLAS (Age, Treatment with systemic antibiotics, leukocyte count, Albumin and Serum creatinine as a measure of renal function) by calculating area under receiver operating curve (AUROC). We identified factors associated with higher mortality risk in each model.

SUMMARY OF RESULTS

From 61 532 intensive care unit stays in the MIMIC-III database, there were 1315 CDI cases. The mortality rate for CDI in the study cohort was 18.33%. AUROC was 0.69 (95% CI, 0.60 to 0.76) for LR, 0.71 (95% CI, 0.62 to 0.77) for RF and 0.72 (95% CI, 0.64 to 0.78) for GBM, while previously AUROC was 0.57 (95% CI, 0.51 to 0.65) for CARDS and 0.63 (95% CI, 0.54 to 0.70) for ATLAS. Albumin, lactate and bicarbonate were significant mortality factors for all the models. Free calcium, potassium, white blood cell, urea, platelet and mean blood pressure were present in at least two of the three models.

CONCLUSION

Our machine learning derived CDI in-hospital mortality prediction model identified pertinent factors that can assist critical care clinicians in identifying patients at high risk of dying from CDI.

Inactivation of the riboswitch-controlled GMP synthase GuaA in Clostridioides difficile is associated with severe growth defects and poor infectivity in a mouse model of infection

Clostridioides difficile is the main cause of nosocomial antibiotic-associated diarrhoea. There is a need for new antimicrobials to tackle this pathogen. Guanine riboswitches have been proposed as promising new antimicrobial targets, but experimental evidence of their importance in C. difficile is missing. The genome of C. difficile encodes four distinct guanine riboswitches, each controlling a single gene involved in purine metabolism and transport. One of them controls the expression of guaA, encoding a guanosine monophosphate (GMP) synthase. Here, using in-line probing and GusA reporter assays, we show that these riboswitches are functional in C. difficile and cause premature transcription termination upon binding of guanine. All riboswitches exhibit a high affinity for guanine characterized by K_d values in the low nanomolar range. Xanthine and guanosine also bind the guanine riboswitches, although with less affinity. Inactivating the GMP synthase (guaA) in C. difficile strain 630 led to cell death in minimal growth conditions, but not in rich medium. Importantly, the capacity of a guaA mutant to colonize the mouse gut was significantly reduced. Together, these results demonstrate the importance of de novo GMP biosynthesis in C. difficile during infection, suggesting that targeting guanine riboswitches with analogues could be a viable therapeutic strategy.

Oxygen transport to mammalian cell and bacteria using nano-sized liposomes encapsulating oxygen molecules

Hypoxic microenvironments emerge as tumor grow, leading to the over-expression and stabilization of hypoxia-inducible factor 1-alpha (HIF-1α). HIF-1α lowers the sensitization against chemotherapy, radiation therapy and photodynamic therapy in cancer. In this study, nano-sized oxygen carrier, namely oxygen dissolved nanoliposome (ODL) was synthesized, and oxygen was efficiently delivered to different types of mammalian cells to help relieve hypoxia. ODL confirmed that oxygen was released without inducing toxicity to cells. After artificially creating hypoxia in cancer cells, normal cells, and immune cells; various parameters such as cell morphology, HIF-1α expression, and degree of hypoxia were examined. The cellular environment was found to be altered by treatment with the ODL. Under hypoxia, the shape of the cells changed, and the cells began to die. After treatment with the ODL, the degree of hypoxia was reduced, indicating that HIF-1α expression and the rate of cell death decreased. Furthermore, bacteria proliferation was observed with the ODL. Therefore, ODL can be used for oxygen delivery platform in cancer therapy. ODL has a potential application in other microorganisms which needs future research.

High Serum Levels of Toxin A Correlate with Disease Severity in Patients with Clostridioides difficile Infection

Cloistridioides difficile (CD) represents a major public healthcare-associated infection causing significant morbidity and mortality. The pathogenic effects of CD are mainly caused by the release of two exotoxins into the intestine: toxin A (TcdA) and toxin B (TcdB). CD infection (CDI) can also cause toxemia, explaining the systemic complications of life-threatening cases. Currently, there is a lack of sensitive assays to detect exotoxins circulating in the blood. Here, we report a new semi-quantitative diagnostic method to measure CD toxins serum levels. The dot-blot assay was modified to separately detect TcdA and TcdB in human serum with a limit of detection at the pg/mL levels. TcdA and TcdB concentrations in the plasma of 35 CDI patients were measured at the time of CDI diagnosis and at the fourth and tenth day after CDI diagnosis and initiation of anti-CDI treatment. TcdA and TcdB levels were compared to those determined in nine healthy blood donors. Toxemia was detected in the plasma of 33 out of the 35 CDI cases. We also assessed the relationship between TcdA serum levels and CDI severity, reporting that at the time of CDI diagnosis the proportion of severe CDI cases with a TcdA serum level > 60 pg/µL was higher than in mild CDI cases (29.4% versus 66.6%, p = 0.04). In conclusion, data reported here demonstrate for the first time that toxemia is much more frequent than expected in CDI patients, and specifically that high serum levels of TcdA correlate with disease severity in patients with CDI.

Danish national guideline for the treatment of Clostridioides difficile infection and use of faecal microbiota transplantation (FMT)

Aim: This Danish national guideline describes the treatment of adult patients with Clostridioides (formerly Clostridium) difficile (CD) infection and the use of faecal microbiota transplantation (FMT). It suggests minimum standard for implementing an FMT service.Method: Four scientific societies appointed members for a working group which conducted a systematic literature review and agreed on the text and recommendations. All clinical recommendations were evalluated for evidence level and grade of recommendation.Results: In CD infection, the use of marketed and experimental antibiotics as well as microbiota-based therapies including FMT are described. An algorithm for evaluating treatment effect is suggested. The organisation of FMT, donor recruitment and screening, laboratory preparation, clinical application and follow-up are described.Conclusion: Updated evidence for the treatment of CD infection and the use of FMT is provided.

Add-on interventions for the prevention of recurrent Clostridioides Difficile infection: A systematic review and network meta-analysis

OBJECTIVES

We aimed to assess the comparative efficacy and safety of adjunctive interventions for the prevention of Clostridioides difficile recurrence.

METHODS

We searched Medline, Embase, CENTRAL, and clinicaltrials.gov up to May 2021. We included randomized controlled trials comparing interventions added to antibiotic therapy for prevention of CDI recurrence, to placebo or each other. Efficacy outcomes were CDI and diarrhea recurrence. Safety outcomes included the incidence of any adverse event (AE), serious AEs, and discontinuation due to AEs. We performed random-effects network meta-analysis. We ranked interventions based on SUCRA (surface under the cumulative ranking curve) probabilities. We assessed confidence in estimates utilizing the CINeMA (Confidence in Network Meta-Analysis) framework.

RESULTS

Fifteen trials (3909 patients) assessed 9 interventions. Oligofructose (OR 0.17; 95% CI, 0.07 to 0.46), NTCD-M3 (OR 0.29; 95% CI, 0.12 to 0.68), rifaximin (OR 0.47; 95% CI, 0.24 to 0.93), RBX2660 (OR 0.47; 95% CI, 0.22 to 0.99), the combination bezlotoxumab/actoxumab (OR 0.47; 95% CI, 0.37 to 0.60), and bezlotoxumab (OR, 0.53; 95% CI, 0.42 to 0.68) were associated with lower incidence of CDI recurrence than placebo (moderate confidence). Oligofructose was ranked highest, however data for oligofructose were derived solely from one small trial. Probiotics, actoxumab and SER-109 were not superior to placebo (low confidence). Probiotics were not well tolerated (low confidence) and actoxumab showed high rates of serious AEs (moderate confidence).

CONCLUSION

Add-on treatment with oligofructose, NTCD-M3 spores, rifaximin, RBX2660, and bezlotoxumab likely reduces the risk of CDI. Evidence on probiotics and SER-109 are uncertain, thus adequately powered trials are warranted.

An RNA-centric global view of Clostridioides difficile reveals broad activity of Hfq in a clinically important gram-positive bacterium

The gram-positive human pathogen Clostridioides difficile has emerged as the leading cause of antibiotic-associated diarrhea. However, little is known about the bacterium's transcriptome architecture and mechanisms of posttranscriptional control. Here, we have applied transcription start site and termination mapping to generate a single-nucleotide-resolution RNA map of C. difficile 5' and 3' untranslated regions, operon structures, and noncoding regulators, including 42 sRNAs. Our results indicate functionality of many conserved riboswitches and predict cis-regulatory RNA elements upstream of multidrug resistance (MDR)-type ATP-binding cassette (ABC) transporters and transcriptional regulators. Despite growing evidence for a role of Hfq in RNA-based gene regulation in C. difficile, the functions of Hfq-based posttranscriptional regulatory networks in gram-positive pathogens remain controversial. Using Hfq immunoprecipitation followed by sequencing of bound RNA species (RIP-seq), we identify a large cohort of transcripts bound by Hfq and show that absence of Hfq affects transcript stabilities and steady-state levels. We demonstrate sRNA expression during intestinal colonization by C. difficile and identify infection-related signals impacting its expression. As a proof of concept, we show that the utilization of the abundant intestinal metabolite ethanolamine is regulated by the Hfq-dependent sRNA CDIF630nc_085. Overall, our study lays the foundation for understanding clostridial riboregulation with implications for the infection process and provides evidence for a global role of Hfq in posttranscriptional regulation in a gram-positive bacterium.

A Review of Clostridioides difficile Infection and Antibiotic-Associated Diarrhea

Antibiotic-associated diarrhea and Clostridioides difficile infection (CDI) occur frequently among adults. The pathophysiology of CDI is related to disruption of normal gut flora and risk factors include hospitalization, use of antibiotic therapy, and older age. Clinical manifestations can range from mild disease to toxic megacolon. Diagnosis is challenging and is based on a combination of clinical symptoms and diagnostic tests. Therapy includes cessation of antibiotics, or use of other agents depending on the severity of illness. Many novel agents for the treatment and prevention of CDI show promise and are under investigation.

Efficient production of recombinant secretory IgA against Clostridium difficile toxins in CHO-K1 cells

Despite the essential role secretory IgAs play in the defense against pathogenic invasion and the proposed value of recombinant secretory IgAs as novel therapeutics, currently there are no IgA-based therapies in clinics. Secretory IgAs are complex molecules and the major bottleneck limiting their therapeutic potential is a reliable recombinant production system. In this report, we addressed this issue and established a fast and robust production method for secretory IgAs in CHO-K1 cells using BAC-based expression vectors. As a proof of principle, we produced IgAs against Clostridium difficile toxins TcdA and TcdB. Recombinant secretory IgAs produced using our expression system showed comparable titers to IgGs, widely used as therapeutic biologicals. Importantly, secretory IgAs produced using our method were functional and could efficiently neutralize Clostridium difficile toxins TcdA and TcdB. These results show that recombinant secretory IgAs can be efficiently produced, thus opening the possibility to use them as therapeutic agents in clinics.

In Vitro and In Vivo Antibacterial Activities of a Novel Quinolone Compound, OPS-2071, against Clostridioides difficile

OPS-2071 is a novel quinolone antibacterial agent characterized by low oral absorption that reduces the risk of adverse events typical of fluoroquinolone class antibiotics. The in vitro and in vivo antibacterial activities of OPS-2071 against Clostridioides difficile were evaluated in comparison to vancomycin and fidaxomicin.

OPS-2071 is a novel quinolone antibacterial agent characterized by low oral absorption that reduces the risk of adverse events typical of fluoroquinolone class antibiotics. The in vitro and in vivo antibacterial activities of OPS-2071 against Clostridioides difficile were evaluated in comparison to vancomycin and fidaxomicin. OPS-2071 exhibited potent antibacterial activity against 54 clinically isolated C. difficile strains with a MIC of 0.125 μg/ml (MIC₅₀) and 0.5 μg/ml (MIC₉₀), making it more active than vancomycin on a concentration basis (MIC₅₀, 2 μg/ml; MIC₉₀, 4 μg/ml) and comparable to fidaxomicin (MIC₅₀, 0.063 μg/ml; MIC₉₀, 8 μg/ml). OPS-2071 showed equally potent antibacterial activity against both hypervirulent and nonhypervirulent strains, while a significant difference in susceptibility to fidaxomicin was observed. Spontaneous resistance to OPS-2071 and vancomycin was not observed; however, resistance to fidaxomicin was observed at 4× MIC. The mutant prevention concentration of OPS-2071 was 16-fold lower than those of fidaxomicin and vancomycin, and the postantibiotic effect of OPS-2071 was longer than those of fidaxomicin and vancomycin. Also, OPS-2071 showed low systemic exposure, with OPS-2071 having 2.9% oral bioavailability at 1 mg/kg in rats. Furthermore, OPS-2071 showed significant in vivo efficacy at 0.0313 mg/kg/day (50% effective doses), 39.0-fold and 52.1-fold lower than those of vancomycin and fidaxomicin, respectively, in a hamster model of C. difficile infection. OPS-2071 has the potential to become a new therapeutic option for treating C. difficile infection.

Clostridioides difficile ribotypes 001 and 126 were predominant in Tehran healthcare settings from 2004 to 2018: a 14-year-long cross-sectional study

Clostridioides difficile infection (CDI) remains a major healthcare problem worldwide, however, little is known about CDI epidemiology in Iran. Between December 2004 and November 2018, 3649 stool samples were collected from patients in 69 hospitals and medical centres in Tehran and were cultured for the presence of C. difficile; isolates were characterized by PCR ribotyping and toxin genes detection. A total of 582 C. difficile isolates were obtained and the overall CDI prevalence was 15.9%; 290 (49.8%) cases were healthcare-associated (HA) and 292 (50.2%) cases were community-associated (CA). Of these, DNA of 513 isolates submitted for ribotyping. The ribotype and/or WEBRIBO type could be assessed in 366 (62.9%) isolates. The most frequent RTs were 001 (n = 75, 12.9%), 126 (n = 65, 11.2%) and 084 (n = 19, 3.3%); the toxin gene profile tcdA ⁺ B ⁺ /cdtA ⁺ B ⁺ (n = 112, 19.2%) was the most common. Fifteen C. difficile isolates (2.6%) did not carry any toxin genes. There was no difference between frequently found RTs in HA-CDI and CA-CDI, except for RT 029 which was more likely to be associated with healthcare origin (12/15, p-value = 0.02). No isolate of RTs 027 or 078 was identified. Importantly, RTs 031, 038, 039, 084, 085 reported previously as RTs with an absence of toxin genes, revealed the presence of toxin genes in our study. Using Simpson's reciprocal index of diversity, we found that RT diversity decreased as the prevalence of the RT 084 increased (R = -0.78, p-value = 0.041). Different patterns in CDI epidemiology underscore the importance of local surveillance and infection control measures in Tehran healthcare settings.

Clostridioides difficile Infection in Chronic Kidney Disease-An Overview for Clinicians

Increased incidence of Clostridioides difficile infection (CDI), occurrence of severe and complicated CDI, and more frequent occurrence of drug-resistant, recurrent or non-hospital CDI has become a worldwide clinical problem. CDI is more common in patients with chronic kidney disease (CKD) than in the general population. CDI seems to be associated with frequent hospitalization, frequently used antibiotic therapy, dysbiosis, and abnormalities of the immune system observed in CKD patients. Dysbiosis is a common disorder found in CKD patients. It may be related to insufficient fiber content in the diet, reduced amount of consumed fluids and often reduced physical activity, constipation, impaired gastrointestinal motility, multidrug pharmacotherapy, and uremic milieu in CKD stage 5. In patients with CKD the clinical manifestations of CDI are similar to the general population; however, more frequent recurrence of CDI and higher prevalence of severe CDI are reported. Moreover, the increase in CDI related mortality is observed more in CKD patients than in the general population. The aim of this review paper is to summarize the current knowledge concerning the epidemiology, pathogenesis, clinical picture, and prevention and treatment in CKD patients.

Proinflammatory Cytokines: Possible Accomplices for the Systemic Effects of Clostridioides difficile Toxin B

Clostridioides difficile infection (CDI) has a serious impact on the healthcare system, and most of its pathogenic effects are mainly due to the activity of toxins A and B (TcdA and TcdB, respectively). The molecular mechanisms of their cytotoxic activity are well known, especially in the colon, where the infection occurs and normally remains localized. However, the mechanisms causing toxic effects on various systemic organs (extraintestinal manifestations) with frequent lethal outcomes in some patients affected by CDI are still poorly understood. Few studies are available that demonstrate low serum levels of Tcds in both experimental animal models and patients with CDI. Until now, it has remained unclear how low levels of circulating Tcds could lead to serious toxic effects. On the basis of our previous in vitro studies, in which the proinflammatory cytokines TNF-alpha and IFN-gamma strongly potentiated the toxic activity of low doses of TcdB, we hypothesize that the presence of both TcdB in the circulation and a systemic proinflammatory cytokine storm may be responsible for the selective severe effects of TcdB in some patients. This may occur in patients with severe CDI and systemic Tcds, in whom proinflammatory cytokines such as TNF-alpha and IFN-gamma reach a significant concentration in the circulation. This hypothesis could identify therapeutic interventions based on the reduction or neutralization of the indirect toxic action of these cytokines.

Gut microbiota characteristics in mice with antibiotic-associated diarrhea

BACKGROUND

Antibiotic-associated diarrhea (AAD), defined as diarrhea that occurs in association with the administration of antibiotics and without another clear etiology, is one of the most common adverse drug events of antibiotics therapy. We established a diarrhea model induced by gentamycin and cefradine to investigate the microbiota characteristics in the intestinal lumen of mice with AAD and provide insights into noteworthy bacteria related to gentamicin and cefradine-associated diarrhea.

RESULTS

The number of OTUs in the model group and the normal group was 983 and 2107, respectively, and 872 identical OTUs were shared between two groups. Species richness and species diversity of intestinal microbe were altered by antibiotics administration. PCoA showed a clear separation between AAD and health control. The dominant phyla of AAD mice were Firmicutes (52.63%) and Proteobacteria (46.37%). Among the genus with top 20 abundance, the relative abundance of 7 genera, Ruminococcus, Blautia, Enterococcus, Eubacterium, Clostridium, Coprococcus, and Aerococcus, were enriched in the model group. Based upon the LEfSe analysis, Enterococcus, Eubacterium, Ruminococcus, and Blautia were identified as potential biomarkers for AAD.

CONCLUSIONS

The bacterial diversity of the intestinal lumen was diminished after gentamicin and cefradine administration. The alterations in the abundance and composition of gut microbiota further led to the dysfunction of gut microbiota. More specifically, gentamicin and cefradine significantly increased the abundance of the opportunistic pathogens, of which Enterococcus and Clostridium were the most prominent and most worthy of attention.

Characteristics and predictors of treatment failure with intravenous tigecycline monotherapy among adult patients with severe Clostridioides (Clostridium) difficile infection: a single-centre observational cohort study

Our aim was to analyze characteristics of treatment failure with intravenous tigecycline monotherapy among adults with severe Clostridioides (Clostridium) difficile infection (CDI). A single-centre observational cohort study was performed between 2014 and 2018. Data were collected by charts review, diagnosis and severity were determined by ESCMID guidelines. Primary outcome was treatment failure, secondary outcomes were in-hospital mortality, relapse, colectomy, and complication rates. Independent predictors of failure were identified using logistic regression. Altogether 110 patients were included, failure occurred in 37.3%. Patients with failure frequently had chronic heart and pulmonary co-morbidities, peritonitis, higher CRP levels, ICU admittance rates and need for total parenteral nutrition and vasopressors. Mostly, CDI-specific mortality and complications contributed to failure. Relapse rates were similar. Chronic pulmonary disease, ileus, total parenteral nutrition, and duration of tigecycline therapy were predictors of failure. We conclude that severe CDI cases with higher risk for tigecycline monotherapy failure might be identified by contributing factors.

Clinical outcomes after faecal microbiota transplant by retention enema in both immunocompetent and immunocompromised patients with recurrent Clostridioides difficile infections at an academic medical centre

BACKGROUND

Recurrent Clostridioides difficile infection (CDI) is one of the most common and challenging infections to treat in healthcare facilities. Faecal microbiota transplantation (FMT) is recommended as a definitive treatment option.

METHODS

We performed a retrospective review of 50 patients from January 2015 to December 2019 who underwent FMT for recurrent CDI. Primary outcome was recurrence of CDI within 12-weeks of FMT and secondary outcomes were the need for repeat FMT, serious adverse outcomes related to FMT and all-cause mortality.

RESULTS

Fifty charts were reviewed, of which 47 cases comprising 17 immunocompromised patients treated with FMT via retention enema were included in the study. The majority of the patients had ≥3 recurrent CDIs (62%). Nine (19%) patients failed to respond to the first FMT and five underwent repeat FMT within four to 12 weeks. The cure rate was 81% after the first FMT (38/47) and 91% after the second FMT treatment (43/47). Serious adverse events occurred in 2% and all-cause mortality was 2% at 90-day follow up.

CONCLUSION

Our study demonstrated the safety and efficacy of FMT administered via retention enema, a simple bedside procedure, for the treatment and prevention of recurrent non-severe and severe CDI with an overall cure rate of 91%.

A newly isolated E. thailandicus strain d5B with exclusively antimicrobial activity against C. difficile might be a novel therapy for controlling CDI

Colitis induced by C. difficile is one of the most common and costly healthcare-related infections for humans. Probiotics are one of the most promising approaches for controlling CDI. Here, we presented the isolation, safety, and probiotic property evaluation of a novel E. thailandicus strain, d5B, with effective antimicrobial activity against C. difficile. Strain d5B showed strong bactericidal effects on at least 54C. difficile strains. Safety tests showed that strain d5B was sensitive to clinically important antibiotics, and had no haemolytic and cytotoxic activities. Whole genomic analysis showed strain d5B only contained one aminoglycoside resistance gene located in the chromosome. Moreover, d5B was devoid of functional virulence genes. Finally, strain d5B exhibited probiotic properties, such as tolerance to the gastrointestinal tract, and adhered well to HT-29 cells. In conclusion, the E. thailandicus strain d5B should be investigated further for useful properties as a novel candidate probiotic for controlling CDI.

Discordant Clostridioides difficile diagnostic assay and treatment practice: a cross-sectional study in a tertiary care hospital, Geneva, Switzerland

OBJECTIVES

To determine the proportion of patients who received a treatment for Clostridioides difficile infection (CDI) among those presenting a discordant C. difficile diagnostic assay and to identify patient characteristics associated with the decision to treat CDI.

DESIGN

Cross-sectional study.

SETTING

Monocentric study in a tertiary care hospital, Geneva, Switzerland.

PARTICIPANTS

Among 4562 adult patients tested for C. difficile between March 2017 and March 2019, 208 patients with discordant tests' results (positive nucleic acid amplification test (NAAT+)/negative enzyme immunoassay (EIA-)) were included.

MAIN OUTCOME MEASURES

Treatment for CDI.

RESULTS

CDI treatment was administered in 147 (71%) cases. In multivariate analysis, an abdominal CT scan with signs of colitis (OR 14.7; 95% CI 1.96 to 110.8) was the only factor associated with CDI treatment.

CONCLUSIONS

The proportion of NAAT+/EIA- patients who received treatment questions the contribution of the EIA for the detection of toxin A/B after NAAT to limit overtreatment. Additional studies are needed to investigate if other factors are associated with the decision to treat.

Regulation of the intestinal microbiota: An emerging therapeutic strategy for inflammatory bowel disease

The rapid development of metagenomics, metabolomics, and metatranscriptomics provides novel insights into the intestinal microbiota factors linked to inflammatory bowel disease (IBD). Multiple microorganisms play a role in intestinal health; these include bacteria, fungi, and viruses that exist in a dynamic balance to maintain mucosal homeostasis. Perturbations in the intestinal microbiota disrupt mucosal homeostasis and are closely related to IBD in humans and colitis in mice. Therefore, preventing or correcting the imbalance of microbiota may serve as a novel prevention or treatment strategy for IBD. We review the most recent evidence for direct or indirect interventions targeting intestinal microbiota for treatment of IBD in order to overcome the current limitations of IBD therapies and shed light on personalized treatment options.

The cytotoxic synergy between Clostridioides difficile toxin B and proinflammatory cytokines: an unholy alliance favoring the onset of Clostridioides difficile infection and relapses

Clostridioides difficile infection (CDI) represents an important health problem worldwide, with significant morbidity and mortality. This infection has also high recurrence rates, whose pathophysiological grounds are still poorly understood. Based on our experiments in vitro with Clostridioides difficile toxin B and existing experimental and clinical evidence, we propose that primary CDI and relapses might be favored by a mechanism that involves the enhancement of the toxicity of toxin B by proinflammatory cytokines, tumor necrosis factor alpha, and interferon gamma on the enteric glial cells and their network in an environment characterized by a strong dysmicrobism.

Diagnosis and treatment of Clostridioides difficile infection

Clostridioides difficile is the main cause of healthcare-associated diarrhoea in adults. The incidence of C.difficile infection (CDI) has increased in recent years. The risk of recurrence of CDI is 15%-25% in a first episode and this risk is increased in subsequent episodes. Toxigenic culture and cytotoxicity tests are the reference techniques for the microbiological diagnosis of CDI. These are laborious and slow techniques and therefore they have been replaced in clinical practice by the application of a multi-step algorithm that includes the detection of glutamate dehydrogenase (GDH), toxins and molecular techniques. The treatment of choice for CDI is Vancomycin. In recent years, new drugs and new treatment strategies have appeared that are especially useful in the treatment of relapses of CDI.

Clostridioides difficile Senses and Hijacks Host Heme for Incorporation into an Oxidative Stress Defense System

Clostridioides difficile infection of the colon leads to severe inflammation and damage to the gastrointestinal epithelium due to the production of potent toxins. This inflammatory tissue damage causes the liberation of high concentrations of host heme at infection sites. Here, we identify the C. difficile heme-sensing membrane protein system (HsmRA) and show that this operon induces a protective response that repurposes heme to counteract antimicrobial oxidative stress responses. HsmR senses vertebrate heme, leading to increased expression of the hsmRA operon and subsequent deployment of HsmA to capture heme and reduce redox damage caused by inflammatory mediators of protection and antibiotic therapy. Strains with inactivated hsmR or hsmA have increased sensitivity to redox-active compounds and reduced colonization persistence in a murine model of relapse C. difficile infection. These results define a mechanism exploited by C. difficile to repurpose toxic heme within the inflamed gut as a shield against antimicrobial compounds.