Toxin production by an emerging strain of Clostridium difficile associated with outbreaks of severe disease in North America and Europe

Prevalence of toxigenic Clostridium difficile in hospitalized patients in the southwestern province of Saudi Arabia: Confirmation using the GeneXpert analysis

Clostridium difficile (Clostridioides difficile) is a leading cause of nosocomial infections in hospitalized patients worldwide. Stool samples were collected from 112 inpatients admitted to different hospitals and were screened for C. difficile GDH + toxin A + B by immunoassay, and all positive samples by immunoassay were processed for molecular detection of C. difficile using the GeneXpert assay. C. difficile strains were detected in 12 (10.71%) out of 112 stool samples using the GDH + toxin A + B immunoassay method and toxigenic C. difficile was confirmed in 5 stool samples using the GeneXpert molecular assay. C. difficile strains were also detected in 7 (8.97%) out of 78 stool samples from intensive care unit patients, 3 (25%) out of 12 stool samples from internal medicine ward patients, 1 (11.11%) out of 9 stool samples from surgery ward patients, and 1 (10%) out of 10 stool samples from isolation ward patients using the GDH + toxin A + B immunoassay method and the toxigenic C. difficile strain was confirmed in 1, 2, 1, and 1 stool samples, respectively, using the GeneXpert molecular assay. Toxigenic C. difficile was confirmed in patients at 4 (51.14%) out of 7 hospitals. In the present study, we also analyzed the clinical information of patients with C. difficile-positive stool samples who were receiving one or more antibiotics during hospitalization. The binary toxin gene (cdt), the tcdC gene, and the C. difficile strain polymerase chain reaction (PCR) ribotype 027 were not detected using the GeneXpert molecular assay among 12 C. difficile-positive samples by immunoassay. This study should aid in the prevention of unnecessary empiric therapy and increase the understanding of the toxigenic C. difficile burden on the healthcare system in the southwestern province of Saudi Arabia.

Gut dysbiosis contributes to the development of Budd-Chiari syndrome through immune imbalance

Budd-Chiari syndrome (B-CS) is a rare and lethal condition characterized by hepatic venous outflow tract blockage. Gut microbiota has been linked to numerous hepatic disorders, but its significance in B-CS pathogenesis is uncertain. First, we performed a case-control study (Ncase = 140, Ncontrol = 63) to compare the fecal microbiota of B-CS and healthy individuals by metagenomics sequencing. B-CS patients' gut microbial composition and activity changed significantly, with a different metagenomic makeup, increased potentially pathogenic bacteria, including Prevotella, and disease-linked microbial function. Imbalanced cytokines in patients were demonstrated to be associated with gut dysbiosis, which led us to suspect that B-CS is associated with gut microbiota and immune dysregulation. Next, 16S ribosomal DNA sequencing on fecal microbiota transplantation (FMT) mice models examined the link between gut dysbiosis and B-CS. FMT models showed damaged liver tissues, posterior inferior vena cava, and increased Prevotella in the disturbed gut microbiota of FMT mice. Notably, B-CS-FMT impaired the morphological structure of colonic tissues and increased intestinal permeability. Furthermore, a significant increase of the same cytokines (IL-5, IL-6, IL-9, IL-10, IL-17A, IL-17F, and IL-13) and endotoxin levels in B-CS-FMT mice were observed. Our study suggested that gut microbial dysbiosis may cause B-CS through immunological dysregulation.

IMPORTANCE

This study revealed that gut microbial dysbiosis may cause Budd-Chiari syndrome (B-CS). Gut dysbiosis enhanced intestinal permeability, and toxic metabolites and imbalanced cytokines activated the immune system. Consequently, the escalation of causative factors led to their concentration in the portal vein, thereby compromising both the liver parenchyma and outflow tract. Therefore, we proposed that gut microbial dysbiosis induced immune imbalance by chronic systemic inflammation, which contributed to the B-CS development. Furthermore, Prevotella may mediate inflammation development and immune imbalance, showing potential in B-CS pathogenesis.

Insoluble polysaccharides produced in plant cell cultures protect from Clostridioides difficile colitis

Clostridioides difficile infection (CDI) poses a significant health threat due to high recurrence rates. Antimicrobial agents are commonly used to manage CDI-related diarrhoea; however, by aggravating intestinal dysbiosis, antibiotics enable C. difficile spores germination and production of toxins, the main virulence factors. Therefore, the binding of exotoxins using adsorbents represents an attractive alternative medication for the prevention and treatment of relapses. In this study, we provided evidence that the natural insoluble polysaccharides, named ABR119, extracted by plant cell cultures, effectively trap C. difficile toxins. In our experiments, ABR119 exhibited no cytotoxicity in vitro and was safely administered in vivo. In the animal model of C. difficile-associated colitis, ABR119 (50 mg/kg body weight) significantly reduced the colonic myeloperoxidase activity and severity of inflammation, preventing body weight loss. These effects were not evident when we treated animals with wheat bran polysaccharides. We did not detect bacterial killing effects of ABR119 against C. difficile nor against bacterial species of the normal gut microbiota. Moreover, ABR119 did not interfere in vitro with the antimicrobial activities of most clinically used antibiotics. In summary, ABR119 holds promise for treating and preventing C. difficile colitis by trapping the bacterial toxins, warranting further studies to assess the ABR119 potential in human infections caused by C. difficile.

Immunoinformatic-guided novel mRNA vaccine designing to elicit immunogenic responses against the endemic Monkeypox virus

Monkeypox virus (MPXV) is an orthopoxvirus, causing zoonotic infections in humans with smallpox-like symptoms. The WHO reported MPXV cases in May 2022 and the outbreak caused significant morbidity threats to immunocompromised individuals and children. Currently, no clinically validated therapies are available against MPXV infections. The present study is based on immunoinformatics approaches to design mRNA-based novel vaccine models against MPXV. Three proteins were prioritized based on high antigenicity, low allergenicity, and toxicity values to predict T- and B-cell epitopes. Lead T- and B-cell epitopes were used to design vaccine constructs, linked with epitope-specific linkers and adjuvant to enhance immune responses. Additional sequences, including Kozak sequence, MITD sequence, tPA sequence, Goblin 5', 3' UTRs, and a poly(A) tail were added to design stable and highly immunogenic mRNA vaccine construct. High-quality structures were predicted by molecular modeling and 3D-structural validation of the vaccine construct. Population coverage and epitope-conservancy speculated broader protection of designed vaccine model against multiple MPXV infectious strains. MPXV-V4 was eventually prioritized based on its physicochemical and immunological parameters and docking scores. Molecular dynamics and immune simulations analyses predicted significant structural stability and binding affinity of the top-ranked vaccine model with immune receptors to elicit cellular and humoral immunogenic responses against the MPXV. The pursuance of experimental and clinical follow-up of these prioritized constructs may lay the groundwork to develop safe and effective vaccine against MPXV.Communicated by Ramaswamy H. Sarma.

Clostridioides difficile and Gut Microbiota: From Colonization to Infection and Treatment

Clostridioides difficile is the main causative agent of antibiotic-associated diarrhea (AAD) in hospitals in the developed world. Both infected patients and asymptomatic colonized individuals represent important transmission sources of C. difficile. C. difficile infection (CDI) shows a large range of symptoms, from mild diarrhea to severe manifestations such as pseudomembranous colitis. Epidemiological changes in CDIs have been observed in the last two decades, with the emergence of highly virulent types and more numerous and severe CDI cases in the community. C. difficile interacts with the gut microbiota throughout its entire life cycle, and the C. difficile's role as colonizer or invader largely depends on alterations in the gut microbiota, which C. difficile itself can promote and maintain. The restoration of the gut microbiota to a healthy state is considered potentially effective for the prevention and treatment of CDI. Besides a fecal microbiota transplantation (FMT), many other approaches to re-establishing intestinal eubiosis are currently under investigation. This review aims to explore current data on C. difficile and gut microbiota changes in colonized individuals and infected patients with a consideration of the recent emergence of highly virulent C. difficile types, with an overview of the microbial interventions used to restore the human gut microbiota.

Genomic and phenotypic studies among Clostridioides difficile isolates show a high prevalence of clade 2 and great diversity in clinical isolates from Mexican adults and children with healthcare-associated diarrhea

Clostridioides difficile (C. difficile) is widely distributed in the intestinal tract of humans, animals, and in the environment. It is the most common cause of diarrhea associated with the use of antimicrobials in humans and among the most common healthcare-associated infections worldwide. Its pathogenesis is mainly due to the production of toxin A (TcdA), toxin B (TcdB), and a binary toxin (CDT), whose genetic variants may be associated with disease severity. We studied genetic diversity in 39 C. difficile isolates from adults and children attended at two Mexican hospitals, using different gene and genome typing methods and investigated their association with in vitro expression of toxins. Whole-genome sequencing in 39 toxigenic C. difficile isolates were used for multilocus sequence typing, tcdA, and tcdB typing sequence type, and phylogenetic analysis. Strains were grown in broth media, and expression of toxin genes was measured by real-time PCR and cytotoxicity in cell-culture assays. Clustering of strains by genome-wide phylogeny matched clade classification, forming different subclusters within each clade. The toxin profile tcdA+/tcdB+/cdt+ and clade 2/ST1 were the most prevalent among isolates from children and adults. Isolates presented two TcdA and three TcdB subtypes, of which TcdA2 and TcdB2 were more prevalent. Prevalent clades and toxin subtypes in strains from children differed from those in adult strains. Toxin gene expression or cytotoxicity was not associated with genotyping or toxin subtypes. In conclusion, genomic and phenotypic analysis shows high diversity among C. difficile isolates from patients with healthcare-associated diarrhea.

IMPORTANCE

Clostridioides difficile is a toxin-producing bacterial pathogen recognized as the most common cause of diarrhea acquired primarily in healthcare settings. This bacterial species is diverse; its global population has been divided into five different clades using multilocus sequence typing, and strains may express different toxin subtypes that may be related to the clades and, importantly, to the severity and progression of disease. Genotyping of children strains differed from adults suggesting toxins might present a reduced toxicity. We studied extensively cytotoxicity, expression of toxins, whole genome phylogeny, and toxin typing in clinical C. difficile isolates. Most isolates presented a tcdA+/ tcdB+/cdt+ pattern, with high diversity in cytotoxicity and clade 2/ST1 was the most prevalent. However, they all had the same TcdA2/TcdB2 toxin subtype. Advances in genomics and bioinformatics tools offer the opportunity to understand the virulence of C. difficile better and find markers for better clinical use.

Encapsulation protocol for fecal microbiota transplantation

Introduction

Clostridioides difficile infections (CDI) continue to pose a challenge for clinicians. Fecal microbiota transplantation (FMT) is an effective treatment option in CDI. Furthermore, recent and ongoing studies suggest potential benefits of FMT in other diseases as well.

Methods

We would like to present a novel protocol for encapsulation of lyophilized fecal material. Our method provides with better compliance as well as improved flexibility, storage and safety.

Results

FMT was conducted in 28 patients with an overall success rate of 82,14% using apsules containing lyophilized stool. 16 of patients were given capsules with lessened bacteria counts. The success rate in this group was 93,75%.

Discussion

The results highlight the still unanswered questions about the mechanism of action and contribute to a wider use of FMT in the clinical praxis and in research.

Clostridioides difficile infection: history, epidemiology, risk factors, prevention, clinical manifestations, treatment, and future options

SUMMARYClostridioides difficile infection (CDI) is one of the major issues in nosocomial infections. This bacterium is constantly evolving and poses complex challenges for clinicians, often encountered in real-life scenarios. In the face of CDI, we are increasingly equipped with new therapeutic strategies, such as monoclonal antibodies and live biotherapeutic products, which need to be thoroughly understood to fully harness their benefits. Moreover, interesting options are currently under study for the future, including bacteriophages, vaccines, and antibiotic inhibitors. Surveillance and prevention strategies continue to play a pivotal role in limiting the spread of the infection. In this review, we aim to provide the reader with a comprehensive overview of epidemiological aspects, predisposing factors, clinical manifestations, diagnostic tools, and current and future prophylactic and therapeutic options for C. difficile infection.

The changing epidemiology of Clostridioides difficile infection and the NAP1/027 strain in two Québec hospitals: a 17-year time-series study

Objective

To describe the epidemiology of healthcare-associated Clostridioides difficile infection (HA-CDI) in two Québec hospitals in Canada following the 2003 epidemic and to evaluate the impact of antibiotic stewardship on the incidence of HA-CDI and the NAP1/027 strain.

Design

Time-series analysis.

Setting

Two Canadian tertiary care hospitals based in Montréal, Québec.

Patients

Patients with a positive assay for toxigenic C. difficile were identified through infection control surveillance. All cases of HA-CDI, defined as symptoms occurring after 72 hours of hospital admission or within 4 weeks of hospitalization, were included.

Methods

The incidence of HA-CDI and antibiotic utilization from 2003 to 2020 were analyzed with available C. difficile isolates. The impact of antibiotic utilization on HA-CDI incidence was estimated by a dynamic regression time-series model. Antibiotic utilization and the proportion of NAP1/027 strains were compared biannually for available isolates from 2010 to 2020.

Results

The incidence of HA-CDI decreased between 2003 and 2020 at both hospitals from 26.5 cases per 10,000 patient-days in 2003 to 4.9 cases per 10,000 patient-days in 2020 respectively. Over the study period, there were an increase in the utilization of third-generation cephalosporins and a decrease in usage of fluoroquinolones and clindamycin. A decrease in fluoroquinolone utilization was associated with a significant decrease in HA-CDI incidence as well as decrease in the NAP1/027 strain by approximately 80% in both hospitals.

Conclusions

Decreased utilization of fluoroquinolones in two Québec hospitals was associated with a decrease in the incidence of HA-CDI and a genotype shift from NAP1/027 to non-NAP1/027 strains.

Contribution of MALDI-TOF mass spectrometry and machine learning including deep learning techniques for the detection of virulence factors of Clostridioides difficile strains

Clostridioides difficile (CD) infections are defined by toxins A (TcdA) and B (TcdB) along with the binary toxin (CDT). The emergence of the 'hypervirulent' (Hv) strain PR 027, along with PR 176 and 181, two decades ago, reshaped CD infection epidemiology in Europe. This study assessed MALDI-TOF mass spectrometry (MALDI-TOF MS) combined with machine learning (ML) and Deep Learning (DL) to identify toxigenic strains (producing TcdA, TcdB with or without CDT) and Hv strains. In total, 201 CD strains were analysed, comprising 151 toxigenic (24 ToxA+B+CDT+, 22 ToxA+B+CDT+ Hv+ and 105 ToxA+B+CDT-) and 50 non-toxigenic (ToxA-B-) strains. The DL-based classifier exhibited a 0.95 negative predictive value for excluding ToxA-B- strains, showcasing accuracy in identifying this strain category. Sensitivity in correctly identifying ToxA+B+CDT- strains ranged from 0.68 to 0.91. Additionally, all classifiers consistently demonstrated high specificity (>0.96) in detecting ToxA+B+CDT+ strains. The classifiers' performances for Hv strain detection were linked to high specificity (≥0.96). This study highlights MALDI-TOF MS enhanced by ML techniques as a rapid and cost-effective tool for identifying CD strain virulence factors. Our results brought a proof-of-concept concerning the ability of MALDI-TOF MS coupled with ML techniques to detect virulence factor and potentially improve the outbreak's management.

Clinical outcomes of clostridioides difficile infection in the very elderly

BACKGROUND

Clostridioides difficile infection (CDI) causes considerable morbidity, mortality, and economic cost. Advanced age, prolonged stay in healthcare facility, and exposure to antibiotics are leading risk factors for CDI. Data on CDI clinical outcomes in the very elderly patients are limited.

METHODS

A retrospective cohort study of patients hospitalized between 2016 and 2018 with CDI. We evaluated demographic clinical and laboratory parameters. Major clinical outcomes were evaluated including duration of hospital stay, admission to intensive care unit (ICU), in-hospital mortality, 30 days post-discharge mortality, and readmission/mortality composite outcome. We compared patients aged up to 80 years (elderly) to those of 80 years old or more (very elderly).

RESULTS

Of 196 patients included in the study, 112 (57%) were very elderly with a mean age of 86 versus 67 years in the elderly group. The duration of hospital stays, and intensive care unit admission frequency were significantly reduced in the very elderly (13 vs. 22 days p = 0.003 and 1.8% vs. 10.7% p = 0.01, respectively). No significant difference was found in the frequencies of in-hospital and in 30 days post-discharge mortality.

CONCLUSIONS

In our cohort, the duration of hospital stay seemed to be shorter in the very elderly with no increase of in-hospital and post-discharge mortality. Although admitted less frequently to ICU, the in-hospital survival of the very elderly was not adversely affected compared to the elderly, suggesting that very advanced age per se should not be a major factor to consider in determining the prognosis of a patient with CDI.

"Primum, non nocere": The Epidemiology of Toxigenic Clostridioides difficile Strains in the Antibiotic Era-Insights from a Prospective Study at a Regional Infectious Diseases Hospital in Eastern Europe

Clostridioides difficile infection (CDI), though identified nearly five decades ago, still remains a major challenge, being associated with significant mortality rates. The strains classified as hypervirulent, notably 027/NAP1/BI, have garnered substantial attention from researchers and clinicians due to their direct correlation with the severity of the disease. Our study aims to elucidate the significance of toxigenic Clostridioides difficile (CD) strains in the clinical and therapeutic aspects of managing patients diagnosed with CDI. We conducted a single-center prospective study, including patients with CDI from north-eastern Romania. We subsequently conducted molecular biology testing to ascertain the prevalence of the presumptive 027/NAP1/BI strain within aforementioned geographic region. The patients were systematically compared and assessed both clinically and biologically, employing standardized and comparative methodologies. The study enrolled fifty patients with CDI admitted between January 2020 and June 2020. Among the investigated patients, 43 (86%) exhibited infection with toxigenic CD strains positive for toxin B genes (tcdB), binary toxin genes (cdtA and cdtB), and deletion 117 in regulatory genes (tcdC), while the remaining 7 (14%) tested negative for binary toxin genes (cdtA and cdtB) and deletion 117 in tcdC. The presence of the presumptive 027/NAP1/BI strains was linked to a higher recurrence rate (35.56%, p = 0.025), cardiovascular comorbidities (65.1% vs. 14.2%, p = 0.016), and vancomycin treatment (55.8% vs. 14.3%, p = 0.049). The findings of our investigation revealed an elevated incidence of colitis attributed to presumptive 027/NAP1/BI. Despite the prevalence of the presumptive 027 strain and its associated heightened inflammation among the patients studied, no significant differences were observed regarding the clinical course or mortality outcomes.

Exploring the Toxin-Mediated Mechanisms in Clostridioides difficile Infection

Clostridioides difficile infection (CDI) is the leading cause of nosocomial antibiotic-associated diarrhea, and colitis, with increasing incidence and healthcare costs. Its pathogenesis is primarily driven by toxins produced by the bacterium C. difficile, Toxin A (TcdA) and Toxin B (TcdB). Certain strains produce an additional toxin, the C. difficile transferase (CDT), which further enhances the virulence and pathogenicity of C. difficile. These toxins disrupt colonic epithelial barrier integrity, and induce inflammation and cellular damage, leading to CDI symptoms. Significant progress has been made in the past decade in elucidating the molecular mechanisms of TcdA, TcdB, and CDT, which provide insights into the management of CDI and the future development of novel treatment strategies based on anti-toxin therapies. While antibiotics are common treatments, high recurrence rates necessitate alternative therapies. Bezlotoxumab, targeting TcdB, is the only available anti-toxin, yet limitations persist, prompting ongoing research. This review highlights the current knowledge of the structure and mechanism of action of C. difficile toxins and their role in disease. By comprehensively describing the toxin-mediated mechanisms, this review provides insights for the future development of novel treatment strategies and the management of CDI.

Reviewing the Clostridioides difficile Mouse Model: Insights into Infection Mechanisms

Clostridioides difficile is an anaerobic, spore-forming bacterium associated with intestinal infection, manifesting a broad spectrum of gastrointestinal symptoms, ranging from mild diarrhea to severe colitis. A primary risk factor for the development of C. difficile infection (CDI) is antibiotic exposure. Elderly and immunocompromised individuals are particularly vulnerable to CDI. A pivotal aspect for comprehending the complexities of this infection relies on the utilization of experimental models that mimic human CDI transmission, pathogenesis, and progression. These models offer invaluable insights into host-pathogen interactions and disease dynamics, and serve as essential tools for testing potential therapeutic approaches. In this review, we examine the animal model for CDI and delineate the stages of infection, with a specific focus on mice. Our objective is to offer an updated description of experimental models employed in the study of CDI, emphasizing both their strengths and limitations.

Core-genome-mediated promising alternative drug and multi-epitope vaccine targets prioritization against infectious Clostridium difficile

Prevention of Clostridium difficile infection is challenging worldwide owing to its high morbidity and mortality rates. C. difficile is currently being classified as an urgent threat by the CDC. Devising a new therapeutic strategy become indispensable against C. difficile infection due to its high rates of reinfection and increasing antimicrobial resistance. The current study is based on core proteome data of C. difficile to identify promising vaccine and drug candidates. Immunoinformatics and vaccinomics approaches were employed to construct multi-epitope-based chimeric vaccine constructs from top-ranked T- and B-cell epitopes. The efficacy of the designed vaccine was assessed by immunological analysis, immune receptor binding potential and immune simulation analyses. Additionally, subtractive proteomics and druggability analyses prioritized several promising and alternative drug targets against C. difficile. These include FMN-dependent nitroreductase which was prioritized for pharmacophore-based virtual screening of druggable molecule databases to predict potent inhibitors. A MolPort-001-785-965 druggable molecule was found to exhibit significant binding affinity with the conserved residues of FMN-dependent nitroreductase. The experimental validation of the therapeutic targets prioritized in the current study may worthy to identify new strategies to combat the drug-resistant C. difficile infection.

Fecal Microbiota Transplantation as Emerging Treatment in European Countries 2.0

Clostridioides difficile infection (CDI) is one of the most common healthcare-associated infections and one of the leading causes of morbidity and mortality in hospitalized patients in the world. Although several antibiotics effectively treat CDI, some individuals may not respond to these drugs and may be cured by transplanting stool from healthy donors. FMT has demonstrated extraordinary cure rates for the cure of CDI recurrences.Moreover, FMT has also been investigated in other disorders associated with the alteration of gut microbiota, such as inflammatory bowel disease (IBD), where the alterations of the gut microbiota ecology have been theorized to play a causative role. Although FMT is currently not recommended to cure IBD patients in clinical practice, several studies have been recently carried out with the ultimate goal to search new therapeutic options to patients.This review summarizes data on the use of FMT for the treatment of both CDI and IBD, with a special attention to highlight studies conducted in European countries.

The Need for European Surveillance of CDI

Since the turn of the millennium, the epidemiology of Clostridioides difficile infection (CDI) has continued to challenge. Changes in clinical presentation, severity of disease, descriptions of new risk factors and the occurrence of outbreaks all emphasised the importance of early diagnosis and standardised surveillance systems. However, a lack of consensus on case definitions, clinical guidelines and optimal laboratory diagnostics across Europe has led to the underestimation of CDI and impeded comparison between countries. These inconsistencies have prevented the true burden of disease from being appreciated.Acceptance that a multi-country CDI surveillance program and optimised diagnostic strategies are required has built the foundations for a more robust, unified surveillance. The concerted efforts of the European Centre for Disease Prevention and Control (ECDC) CDI networks led to the development of the European surveillance protocol and an over-arching long-term CDI surveillance strategy for 2014-2020, which has been followed by the development of surveillance systems in at least 20 European countries. However, surveillance activities in individual countries have slowed during the COVID-19 pandemic as resources were diverted to the global health crisis. A renewed and strengthened focus on CDI surveillance and prevention is therefore urgently needed post COVID-19.

Comparative Genomics of Clostridioides difficile

Clostridioides difficile, a Gram-positive spore-forming anaerobic bacterium, has rapidly emerged as the leading cause of nosocomial diarrhoea in hospitals. The availability of large numbers of genome sequences, mainly due to the use of next-generation sequencing methods, has undoubtedly shown their immense advantages in the determination of C. difficile population structure. The implementation of fine-scale comparative genomic approaches has paved the way for global transmission and recurrence studies, as well as more targeted studies, such as the PaLoc or CRISPR/Cas systems. In this chapter, we provide an overview of recent and significant findings on C. difficile using comparative genomic studies with implications for epidemiology, infection control and understanding of the evolution of C. difficile.

Ribotypes and New Virulent Strains Across Europe

Clostridioides (formerly Clostridium) difficile is a major bacterial cause of post-antibiotic diarrhoea. The epidemiology of C. difficile infections (CDIs) has dramatically changed since the early 2000s, with an increasing incidence and severity across Europe. This trend is partly due to the emergence and rapid worldwide spread of the hypervirulent and epidemic PCR ribotype 027. Profiles of patients with CDI have also evolved, with description of community-acquired (CA) infections in patients with no traditional risk factors for CDI. However, epidemiological studies indicated that some European countries have successfully controlled the dissemination of the 027 clone whereas other countries reported the emergence of other virulent or unusual strains. The aims of this review are to summarize the current European CDI epidemiology and to describe the new virulent C. difficile strains circulating in Europe, as well as other potential emerging strains described elsewhere. Standardized typing methods and surveillance programmes are mandatory for a better understanding and monitoring of CDI in Europe.

The ESCMID Study Group for Clostridioides difficile: History, Role, and Perspectives

Clostridioides difficile (C. difficile) is a major nosocomial pathogen but is also increasingly recognised as an important diarrhoeal pathogen in the community, not always associated with antibiotics. The European Society of Clinical Microbiology and Infectious Diseases (ESCMID) Study Group for C. difficile (ESGCD) is a group of clinicians, scientists, and others from many European countries and further afield, who share a common interest in C. difficile. The aims of the Study Group are centred around raising the profile of  C. difficile infection (CDI) in humans and animals, fostering collaboration amongst centres in different European countries and providing a forum for discussing and disseminating information. One of the principal aims of the Study Group is to raise awareness of C. difficile infections in Europe. ESGCD has a particular interest in the development and dissemination of European guidance on prevention, diagnosis, and treatment of CDI. This chapter will discuss the organisation of ESGCD within the ESCMID Study Group structure, the origins of the Study Group, the aims, and objectives of the group, and will highlight some of the past and present activities of ESGCD in relation to these.

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.

Pathogenicity and virulence of Clostridioides difficile

Clostridioides difficile is the most common cause of nosocomial antibiotic-associated diarrhea, and is responsible for a spectrum of diseases characterized by high levels of recurrence, morbidity, and mortality. Treatment is complex, since antibiotics constitute both the main treatment and the major risk factor for infection. Worryingly, resistance to multiple antibiotics is becoming increasingly widespread, leading to the classification of this pathogen as an urgent threat to global health. As a consummate opportunist, C. difficile is well equipped for promoting disease, owing to its arsenal of virulence factors: transmission of this anaerobe is highly efficient due to the formation of robust endospores, and an array of adhesins promote gut colonization. C. difficile produces multiple toxins acting upon gut epithelia, resulting in manifestations typical of diarrheal disease, and severe inflammation in a subset of patients. This review focuses on such virulence factors, as well as the importance of antimicrobial resistance and genome plasticity in enabling pathogenesis and persistence of this important pathogen.

Clostridioides difficile infection leading to fulminant colitis with toxic megacolon

Clostridioidesdifficile infection (CDI) is the culprit of millions of nosocomial infections in the United States. Programs that successfully decrease its incidence, therefore, render cost savings for the healthcare system. Toxic megacolon and perforation are two of the most significant complications with increased mortality rates. We report a 23-year-old nursing home resident hospitalized for fever, cough, and green sputum. After 3 days of antibiotic therapy, he developed abdominal distension, diarrhea, and vomiting and underwent a total colectomy. The colon was dilated to a maximum of 11 cm with markedly edematous mucosa and yellow pseudomembranes. Qualitative PCR of the stool detected Clostridioides difficile toxin B gene. While there is no consensus for the required interval between antibiotic treatment and CDI, this presentation 3 days after starting the antibiotic therapy is earlier than most proposed ranges.

Engineered Secretory Immunoglobulin A provides insights on antibody-based effector mechanisms targeting Clostridiodes difficile

Secretory (S) Immunoglobin (Ig) A is the predominant mucosal antibody, which mediates host interactions with commensal and pathogenic microbes, including Clostridioides difficile. SIgA adopts a polymeric IgA structure that is bound by secretory component (SC). Despite significance, how SIgA supports diverse effector mechanisms is poorly characterized and SIgA-based therapies nonexistent. We engineered chimeric (c) SIgAs, in which we replaced SC domain D2 with a single domain antibody or a monomeric fluorescent protein, allowing us to investigate and enhance SIgA effector mechanisms. cSIgAs exhibited increased neutralization potency against C. difficile toxins, promoted bacterial clumping and cell rupture, and decreased cytotoxicity. cSIgA also allowed us to visualize and/or quantify C. difficile morphological changes and clumping events. Results reveal mechanisms by which SIgA combats C. difficile infection, demonstrate that cSIgA design can modulate these mechanisms, and demonstrate cSIgA's adaptability to modifications that might target a broad range of antigens and effector mechanisms.

An epidemiological surveillance study (2021-2022): detection of a high diversity of Clostridioides difficile isolates in one tertiary hospital in Chongqing, Southwest China

BACKGROUND

Clostridioides difficile is a bacterium that causes antibiotic-associated infectious diarrhea and pseudomembranous enterocolitis. The impact of C. difficile infection (CDI) in China has gained significant attention in recent years. However, little epidemiological data are available from Chongqing, a city located in Southwest China. This study aimed to investigate the epidemiological pattern of CDI and explore the drug resistance of C. difficile isolates in Chongqing.

METHODS

A case-control study was conducted to investigate the clinical infection characteristics and susceptibility factors of C. difficile. The features of the C. difficile isolates were evaluated by testing for toxin genes and using multi-locus sequence typing (MLST). The susceptibility of strains to nine antibiotics was determined using agar dilution technique.

RESULTS

Out of 2084 diarrhea patients, 90 were tested positive for the isolation of toxigenic C. difficile strains, resulting in a CDI prevalence rate of 4.32%. Tetracycline, cephalosporins, hepatobiliary disease, and gastrointestinal disorders were identified as independent risk factors for CDI incidence. The 90 strains were classified into 21 sequence types (ST), with ST3 being the most frequent (n = 25, 27.78%), followed by ST2 (n = 10, 11.11%) and ST37 (n = 9, 10%). Three different toxin types were identified: 69 (76.67%) were A+B+CDT-, 12 (13.33%) were A-B+CDT-, and 9 (10%) were A+B+CDT+. Although substantial resistance to erythromycin (73.33%), moxifloxacin (62.22%), and clindamycin (82.22%), none of the isolates exhibited resistance to vancomycin, tigecycline, or metronidazole. Furthermore, different toxin types displayed varying anti-microbial characteristics.

CONCLUSIONS

The strains identified in Chongqing, Southwest China, exhibited high genetic diversity. Enhance full awareness of high-risk patients with HA-CDI infection, particularly those with gastrointestinal and hepatocellular diseases, and emphasize caution in the use of tetracycline and capecitabine. These findings suggest that a potential epidemic of CDI may occur in the future, emphasizing the need for timely monitoring.

Virulence and genomic diversity among clinical isolates of ST1 (BI/NAP1/027) Clostridioides difficile

Clostridioides difficile produces toxins that damage the colonic epithelium, causing colitis. Variation in disease severity is poorly understood and has been attributed to host factors and virulence differences between C. difficile strains. We test 23 epidemic ST1 C. difficile clinical isolates for their virulence in mice. All isolates encode a complete Tcd pathogenicity locus and achieve similar colonization densities. However, disease severity varies from lethal to avirulent infections. Genomic analysis of avirulent isolates reveals a 69-bp deletion in the cdtR gene, which encodes a response regulator for binary toxin expression. Deleting the 69-bp sequence in virulent R20291 strain renders it avirulent in mice with reduced toxin gene transcription. Our study demonstrates that a natural deletion within cdtR attenuates virulence in the epidemic ST1 C. difficile isolates without reducing colonization and persistence. Distinguishing strains on the basis of cdtR may enhance the specificity of diagnostic tests for C. difficile colitis.

CLINICAL OUTCOME AND SEVERITY OF CLOSTRIDIOIDES (CLOSTRIDIUM) DIFFICILE INFECTION AT A TERTIARY REFERRAL HOSPITAL IN BRAZIL

•The outcomes of CDI were evaluated in 65 patients with CDI in a Brazilian tertiary hospital. •Lack of clinical improvement after treatment and the severity score (ATLAS) increased the risk of death. •The use of multiple antimicrobial agents was associated with longer hospital stays. •Patients with high Charlson comorbidity index (>7) were more likely to recur. Background - Clostridioides difficile infection (CDI) is a potentially severe disease that can present with refractoriness, recurrence, and evolution to death. In Brazil, the epidemiology of CDI seems to differ from that of the United States and most European countries, with only one ribotype (RT) 027-related case and a high prevalence of RT106. Objective - The aim of this study was to evaluate the outcomes of CDI and its possible association with ribotypes at a university hospital in Brazil. Methods - A total of 65 patients with CDI were included and stool samples were submitted to A/B toxin detection and toxigenic culture, and toxigenic isolates (n=44) were also PCR ribotyped. Results - Patients' median age was 59 (20-87) years and there were 16 (24.6%) deaths. The median Charlson comorbidity index (CCI) was 4 (0-15) and 16.9% of the patients had CCI ≥8. The ATLAS score and non-improvement of diarrhea were related to higher mortality. A longer length of hospitalization was related to the enteral nutrition and use of multiple antibiotics. The period between CDI diagnosis and hospital discharge was longer in those who received new antibiotics after diagnosis, multiple antibiotics, and required intensive care treatment. Recurrence was associated with CCI >7. Twenty ribotypes were identified and RT106 was the most frequently detected strain (43.2%). No relationship was observed between the ribotypes and outcomes. CDI was present in patients with more comorbidities. Conclusion - Risk factors for higher mortality, longer hospital stay and recurrence were identified. A diversity of ribotypes was observed and C. difficile strains were not related to the outcomes.

Insights into the Evolving Epidemiology of Clostridioides difficile Infection and Treatment: A Global Perspective

Clostridioides difficile remains an important public health threat, globally. Since the emergence of the hypervirulent strain, ribotype 027, new strains have been reported to cause C. difficile infection (CDI) with poor health outcomes, including ribotypes 014/020, 017, 056, 106, and 078/126. These strains differ in their geographic distribution, genetic makeup, virulence factors, and antimicrobial susceptibility profiles, which can affect their ability to cause disease and respond to treatment. As such, understanding C. difficile epidemiology is increasingly important to allow for effective prevention measures. Despite the heightened epidemiological surveillance of C. difficile over the past two decades, it remains challenging to accurately estimate the burden and international epidemiological trends given the lack of concerted global effort for surveillance, especially in low- and middle-income countries. This review summarizes the changing epidemiology of C. difficile based on available data within the last decade, highlights the pertinent ribotypes from a global perspective, and discusses evolving treatments for CDI.

Double-Blind, Placebo-Controlled Study of Bezlotoxumab in Children Receiving Antibacterial Treatment for Clostridioides difficile Infection (MODIFY III)

BACKGROUND

Therapies to prevent recurrence of Clostridioides difficile infection (CDI) in pediatric patients are needed. Bezlotoxumab is a fully human monoclonal antibody approved for prevention of recurrent CDI in adults. We assessed the pharmacokinetics, safety, tolerability, and efficacy of bezlotoxumab in pediatric patients.

METHODS

MODIFY III was a multicenter, double-blind, placebo-controlled study of bezlotoxumab in children (1 to <18 years) receiving antibacterial treatment for CDI. Participants were randomized 3:1 to receive a single infusion of bezlotoxumab (10 mg/kg) or placebo and were stratified by age at randomization (cohort 1: 12 to <18 years, cohort 2: 1 to <12 years). The primary objective was to characterize bezlotoxumab pharmacokinetics to support dose selection for pediatric patients; the primary endpoint was the area under the bezlotoxumab serum concentration-time curve (AUC0-inf). Safety, tolerability, and efficacy were monitored for 12 weeks post-infusion.

RESULTS

A total of 148 participants were randomized and 143 were treated: 107 with bezlotoxumab and 36 with placebo (cohort 1 n = 60, cohort 2 n = 83; median age 9.0 years); 52.4% of participants were male and 80.4% were white. Geometric mean ratios (90% CI) for bezlotoxumab AUC0-inf were 1.06 (0.95, 1.18) and 0.82 (0.75, 0.89) h * μg/mL for cohorts 1 and 2, respectively. Bezlotoxumab 10 mg/kg was generally well-tolerated with an adverse event profile similar to placebo, including no treatment discontinuations due to adverse events. CDI recurrence was low and comparable for bezlotoxumab (11.2%) and placebo (14.7%).

CONCLUSIONS

The results of this study support the bezlotoxumab dose of 10 mg/kg for pediatric patients.

TRIAL REGISTRATION

NCT03182907 at ClinicalTrials.gov.

Regulation of Clostridial Toxin Gene Expression: A Pasteurian Tradition

The alarming symptoms attributed to several potent clostridial toxins enabled the early identification of the causative agent of tetanus, botulism, and gas gangrene diseases, which belongs to the most famous species of pathogenic clostridia. Although Clostridioides difficile was identified early in the 20th century as producing important toxins, it was identified only 40 years later as the causative agent of important nosocomial diseases upon the advent of antibiotic therapies in hospital settings. Today, C. difficile is a leading public health issue, as it is the major cause of antibiotic-associated diarrhea in adults. In particular, severe symptoms within the spectrum of C. difficile infections are directly related to the levels of toxins produced in the host. This highlights the importance of understanding the regulation of toxin synthesis in the pathogenicity process of C. difficile, whose regulatory factors in response to the gut environment were first identified at the Institut Pasteur. Subsequently, the work of other groups in the field contributed to further deciphering the complex mechanisms controlling toxin production triggered by the intestinal dysbiosis states during infection. This review summarizes the Pasteurian contribution to clostridial toxin regulation studies.

Microbiota and epigenetics: Health impact

Epigenetic changes associated with disease development and progressions are of increasing importance because of their potential diagnostic and therapeutic applications. Several epigenetic changes associated with chronic metabolic disorders have been studied in various diseases. Epigenetic changes are mostly modulated by environmental factors, including the human microbiota living in different parts of our bodies. The microbial structural components and the microbially derived metabolites directly interact with host cells, thereby maintaining homeostasis. Microbiome dysbiosis, on the other hand, is known to produce elevated levels of disease-linked metabolites, which may directly affect a host metabolic pathway or induce epigenetic changes that can lead to disease development. Despite their important role in host physiology and signal transduction, there has been little research into the mechanics and pathways associated with epigenetic modifications. This chapter focuses on the relationship between microbes and their epigenetic effects in diseased pathology, as well as on the regulation and metabolism of the dietary options available to the microbes. Furthermore, this chapter also provides a prospective link between these two important phenomena, termed "Microbiome and Epigenetics."

Prevalence and molecular characterization of Clostridioides difficile infection in China over the past 5 years: a systematic review and meta-analysis

OBJECTIVES

The aim of this study was to provide an overview of the prevalence and molecular characteristics of Clostridioides difficile infection (CDI) in China in the past 5 years.

METHODS

A systematic literature review was conducted according to the preferred reporting items for systematic reviews and meta-analyses guidelines. Nine databases were searched for relevant studies published between January 2017 and February 2022. The Joanna Briggs Institute critical appraisal tool was used to assess the quality of included studies, and R software version 4.1.3 was used for data analysis. Funnel plots and Egger regression tests were also performed to assess publication bias.

RESULTS

A total of 50 studies were included in the analysis. The pooled prevalence of CDI in China was 11.4% (2696/26,852). The main circulating C. difficile strains in southern China were ST54, ST3, and ST37, consistent with the overall situation in China. However, the most prevalent genotype in northern China was ST2, which was previously underappreciated.

CONCLUSION

Based on our findings, increased awareness and management of CDI is necessary to reduce the prevalence of CDI in China.

Omadacycline and Clostridioides difficile: A Systematic Review of Preclinical and Clinical Evidence

OBJECTIVE

The objective of this systematic review is to summarize in vitro, preclinical, and human data related to omadacycline and Clostridioides difficile infection (CDI).

DATA SOURCES

PubMed and Google Scholar were searched for "omadacycline" AND ("Clostridium difficile" OR "C difficile" OR "Clostridioides difficile") for any studies published before February 15, 2022. The US Food and Drug Administration (FDA) Adverse Events Reporting System (AERS) was searched for omadacycline (for reports including "C. difficile" or "CDI" or "gastrointestinal infection"). The publications list publicly available at Paratek Pharmaceuticals, Inc. Web site was reviewed.

STUDY SELECTION AND DATA EXTRACTION

Publications presenting primary data on omadacycline and C. difficile published in English were included.

DATA SYNTHESIS

Preclinical and clinical evidence was extracted from 14 studies. No case reports in indexed literature and no reports on FDA AERS were found. Omadacycline has potent in vitro activity against many C. difficile clinical strains and diverse ribotypes. In phase 3 studies, there were no reports of CDI in patients who received omadacycline for either community-acquired bacterial pneumonia or acute bacterial skin and skin structure infection.

RELEVANCE TO PATIENT CARE AND CLINICAL PRACTICE

Omadacycline should be considered a low-risk antibiotic regarding its propensity to cause CDI.

CONCLUSIONS

Reducing the burden of CDI on patients and the health care system should be a priority. Patients with appropriate indications who are at heightened risk of CDI may be suitable candidates for omadacycline therapy. In these patients, omadacycline may be preferable to antibiotics with a high CDI risk.

Clostridioides difficile infection: traversing host-pathogen interactions in the gut

C. difficile is the primary cause for nosocomial infective diarrhoea. For a successful infection, C. difficile must navigate between resident gut bacteria and the harsh host environment. The perturbation of the intestinal microbiota by broad-spectrum antibiotics alters the composition and the geography of the gut microbiota, deterring colonization resistance, and enabling C. difficile to colonize. This review will discuss how C. difficile interacts with and exploits the microbiota and the host epithelium to infect and persist. We provide an overview of C. difficile virulence factors and their interactions with the gut to aid adhesion, cause epithelial damage and mediate persistence. Finally, we document the host responses to C. difficile, describing the immune cells and host pathways that are associated and triggered during C. difficile infection.

Pediatric diarrhea patients living in urban areas have a higher incidence of Clostridioides difficile infection

Clostridioides difficile infection (CDI) is a major cause of antibiotic-associated diarrhea and an unappreciated contributor to child mortality in low- and middle-income countries where the diagnosis may be difficult. There is little information about the prevalence of CDI among infants, children, and adolescents in Africa. Using a cross-sectional design, seventy-six samples were collected from pediatric patients presenting with diarrhea, including infants (≤ 2 years old), children (2-12 years), and adolescents (13 ≤17 years) from three hospitals between January and December 2019. Demographic data, medical history, and prior antibiotic use were recorded. Toxigenic culture and PCR were used to detect and validate the presence of C. difficile in the samples. Data obtained were analyzed using descriptive and inferential statistics. A total of 29 (38.7%), 39 (52.0%) and 7 (9.3%) samples were from infants, children, and adolescents, respectively. The average age of the patients was 4.4 years. Of these samples, 31 (41%) were positive for C. difficile by culture and were verified by PCR amplification of C. difficile-specific genes (tcdA and tcdB). The most positive cases were children (53.3%) and infants (40.0%) with the majority of them residing in urban areas. Forty-nine (66.2%) of the patients had no known antibiotics exposure, whereas 29.0% and 29.7% reported the use of over-the-counter antibiotics at 14 and 90 days, prior to the hospital visit, respectively. CDI is relatively common among children with diarrhea in Northern Nigeria. Therefore, for effective management and treatment, more attention should be given to testing for C. difficile as one of the causative agents of diarrhea.

Virulence and genomic diversity among clinical isolates of ST1 (BI/NAP1/027) Clostridioides difficile

Clostridioides difficile (C. difficile) , a leading cause of nosocomial infection, produces toxins that damage the colonic epithelium and results in colitis that varies from mild to fulminant. Variation in disease severity is poorly understood and has been attributed to host factors (age, immune competence and intestinal microbiome composition) and/or virulence differences between C. difficile strains, with some, such as the epidemic BI/NAP1/027 (MLST1) strain, being associated with greater virulence. We tested 23 MLST1(ST1) C. difficile clinical isolates for virulence in antibiotic-treated C57BL/6 mice. All isolates encoded a complete Tcd pathogenicity locus and achieved similar colonization densities in mice. Disease severity varied, however, with 5 isolates causing lethal infections, 16 isolates causing a range of moderate infections and 2 isolates resulting in no detectable disease. The avirulent ST1 isolates did not cause disease in highly susceptible Myd88 -/- or germ-free mice. Genomic analysis of the avirulent isolates revealed a 69 base-pair deletion in the N-terminus of the cdtR gene, which encodes a response regulator for binary toxin (CDT) expression. Genetic deletion of the 69 base-pair cdtR sequence in the highly virulent ST1 R20291 C. difficile strain rendered it avirulent and reduced toxin gene transcription in cecal contents. Our study demonstrates that a natural deletion within cdtR attenuates virulence in the epidemic ST1 C. difficile strain without reducing colonization and persistence in the gut. Distinguishing strains on the basis of cdtR may enhance the specificity of diagnostic tests for C. difficile colitis.

Characterization of a Clostridioides difficile ST-293 isolate from a recurrent infection in Argentina

Clostridioides difficile is an opportunistic spore-forming pathogen responsible for antibiotic-associated diarrhea in humans. C. difficile produces two main toxins: TcdA and TcdB as well as a third toxin named binary toxin (CDT) that is also involved in virulence. The present study aimed at characterizing the C. difficile isolate ALCD3 involved in a relapse episode of nosocomial infection. Molecular characterization showed that isolate ALCD3 belongs to toxinotype 0/v and the MLST analysis demonstrated allelic profile adk:91, atpA:1, dxr:2, glyA: 1, recA:27, sodA: 1 and tpi:1 which corresponds to ST293 (MLST clade: 1). During growth, isolate ALCD3 showed an early increase in the sporulation ratio as well as maximal values of heat resistant forms after 2 days of incubation. Both sporulation kinetics and production of heat resistant forms were faster for isolate ALCD3 than for the reference strain VPI 10463. Germination in the presence of the natural germinant taurocholate was faster for isolate ALCD3 than for strain VPI 10463, which indicates that isolate ALCD3 starts cortex hydrolysis earlier than strain VPI 10463. Furthermore, the co-germinant glycine, induces rapid release of dipicolinic acid (DPA) in isolate ALCD3. These findings indicate that isolate ALCD3 is particularly efficient in both sporulation and germination. The present work represents the first report of the circulation of C. difficile ST293 in Argentina. The ability of isolate ALCD3 to produce toxins and its high sporulation/germination capacity are key features compatible with a microorganism with high dissemination potential and the possibility of inducing recurrent infections.

Sentinel surveillance and epidemiology of Clostridioides difficile in Denmark, 2016 to 2019

BackgroundSince 2008, Danish national surveillance of Clostridioides difficile has focused on binary toxin-positive strains in order to monitor epidemic types such as PCR ribotype (RT) 027 and 078. Additional surveillance is needed to provide a more unbiased representation of all strains from the clinical reservoir.AimSetting up a new sentinel surveillance scheme for an improved understanding of type distribution relative to time, geography and epidemiology, here presenting data from 2016 to 2019.MethodsFor 2─4 weeks in spring and autumn each year between 2016 and 2019, all 10 Danish Departments of Clinical Microbiology collected faecal samples containing toxigenic C. difficile. Isolates were typed at the national reference laboratory at Statens Serum Institut. The typing method in 2016-17 used tandem-repeat-sequence typing, while the typing method in 2018-19 was whole genome sequencing.ResultsDuring the study period, the sentinel surveillance scheme included ca 14-15% of all Danish cases of C. difficile infections. Binary toxin-negative strains accounted for 75% and 16 of the 20 most prevalent types. The most common sequence types (ST) were ST2/13 (RT014/020) (19.5%), ST1 (RT027) (10.8%), ST11 (RT078) (6.7%), ST8 (RT002) (6.6%) and ST6 (RT005/117) (5.1%). The data also highlighted geographical differences, mostly related to ST1 and temporal decline of ST1 (p = 0.0008) and the increase of ST103 (p = 0.002), ST17 (p = 0.004) and ST37 (p = 0.003), the latter three binary toxin-negative.ConclusionSentinel surveillance allowed nationwide monitoring of geographical differences and temporal changes in C. difficile infections in Denmark, including emerging types, regardless of binary toxin status.

Comparative biofilm-forming ability between Clostridioides difficile strains isolated in Latin America and the epidemic NAP1/027 strain

Introduction

One of the challenges in treating Clostridioides difficile infection (CDI) is that the bacterium forms biofilms, a critical virulence mechanism known to promote antibiotic resistance and, as a result, consequently, a higher recurrence of the disease. The goal of this study was to compare the ability of three MLST Clade 2 strains to form a biofilm in vitro: ICC-45 (ribotype SLO231/UK[CE]821), a ST41 toxinotype IXb isolated in Brazil; and two epidemic NAP1/027/ST01 strains: NAP1/027/ST01 (LIBA5756), isolated during a 2010 outbreak in Costa Rica and the reference epidemic strain NAP1/027/ST01 (R20291); and ATCC700057, a non-toxigenic strain.

Methods

The ability of strains to form biofilm was evaluated using crystal violet staining. In addition, samples were stained with the Film Tracer biofilm matrix (Invitrogen®) and the biofilm matrix thickness was measured using confocal microscopy. The matrix architecture was determined using Scanning electron microscop. Confocal microscopy was used to detect the presence of toxin A (tcdA) using an anti-Clostridioides difficile TcdA antibody. The expression of virulence genes (tcdA, tcdB, tcdC, cdtB, spo0A, slpA, cwp66 and cwp84) was examined, as well as the effect of antibiotics metronidazole (MTZ) and vancomycin (VAN) on biofilm growth.

Results

All of the strains tested formed a moderate biofilm with 1.1 <DO_570nm>3.5. After 72h, biofilm biomass of the NAP1/027/ST01 epidemic strains (LIBA5756 and R20291) was significantly higher than ICC-45 and ATCC 700057 biofilms, as confirmed by electron and confocal microscopy. At 120h, the LIBA5756 biofilm biomass decreased compared to other strains. The toxigenic strains R20291 or LIBA 5756 had higher expression of genes tcdA, tcdB, tcdC, cdtA, slpA and spo0A than ICC-45, but there were no significant differences in the expression levels of cdtB, cwp66 and cwp84. In epidemic strains, VAN and MTZ inhibited biofilm formation; however, in the ICC-45 strain, MIC concentrations of VAN and MIC and 4MIC of MTZ did not inhibit biofilm formation.

Conclusion

The three MLST Clade 2 isolated from different rybotipes, two of which were isolated from Latin America, are competent biofilm-forming bacteria, indicating their ability to induce C. difficile infection recurrence, making treatment difficult.

Higher In Vivo Fecal Concentrations of Clostridioides difficile Toxins A and B in Patients With North American Pulsed-Field Gel Electrophoresis Type 1/Ribotype 027 Strain Infection

Ultrasensitive, quantitative Clostridioides difficile stool toxin measurement demonstrated significantly higher concentrations of toxins A and B in patients infected with the North American pulsed-field gel electrophoresis type 1/ribotype 027 (NAP-1/027) strain compared with other strains, providing in vivo confirmation of the in vitro association between NAP-1/027 and elevated toxin production.

Isolation, molecular typing and antimicrobial resistance of Clostridium difficile in dogs and cats in Lanzhou city of Northwest China

Clostridium difficile infection (CDI) in human and animals belonged usually to antibiotic-associated diarrhea, ranging in severity from mild to life-threatening intestinal tract illnesses. This study aimed to isolation and characterization, toxin genes test, molecular typing, and drug sensitivity of Clostridium difficile (C. difficile) which were isolated from clinical diseased dogs and cats. A total of 247 clinical samples were collected from five animal hospitals in Lanzhou City of Northwest China, of which dogs and cats accounted for 74.9% (185/247) and 25.1% (62/247), respectively. We successfully identified 24 C. difficile strains by 16S rRNA and Matrix-Assisted Laser Desorption/Ionization Time of Fight Mass Spectroscopy (MALDI-TOF-MS). 10.3% (19/185) of dogs and 8.1% (5/62) of cats were positive for C. difficile. Among them, 16 strains were toxic and 8 were non-toxic, with a toxic rate of 57.9% (11/19) in dogs and 100% (5/5) in cats. A total of 10 STs and 10 RTs were identified in this study. The percentages of ST42 (RT106) and ST2 (RT014/LW01) among 16 toxic strains were 41.7 and 12.5%, respectively. However, ST3 (RT001), ST1 (RT027), ST133 (LW04), and ST-UN (LW04) had only one strain. ST42 (RT106) was the most common genotype and RT027 strain was first isolated in China from pets. Antimicrobial susceptibility test showed that isolates were extremely sensitive to vancomycin and metronidazole but were resistant to erythromycin and ciprofloxacin. The drug resistant rates to clindamycin, levofloxacin, moxifloxacin and meropenem were 62.5, 20.8, 16.7, and 8.3%, respectively. In conclusion, C. difficile was quietly prevalent in dogs and cats in Lanzhou city with RT106 and RT014 as the main ribotypes. The CDI in pets should be paying more attention and further studies are needed.

Comparison of clinical severity, genotype and toxin gene expression of binary toxin-producing Clostridioides difficile clinical isolates in Japan

The emerging Clostridioides difficile strain BI/NAP1/027 has been reported to be associated with more severe clinical symptoms and higher mortality rates, thought in part due to production of a novel binary toxin alongside conventional A and B toxins. However, recent studies suggest that this may not always be the case. Therefore, the purpose of this report was to investigate the correlation between clinical severity and microbiological characteristics of CDT-producing C. difficile isolates in Japan. Eight Japanese isolates of CDT producing C. difficile were investigated using genotyping, cytotoxic activity assays and toxin gene expression. Correlation with clinical severity was performed retrospectively using the patient record. Three of eight patients were assessed as having severe C. difficile infection (CDI). PCR ribotyping resolved six ribotypes including ribotype 027. No specific genes were identified determining severe compared with non-severe cases. Positive correlation of expression levels of tcdA, tcdB and cdtB were observed although these expression levels were not correlated with cytotoxicity. CDI severity index neither correlated with toxin gene expression level nor cytotoxicity. These data indicate that the possession of the CDT gene and toxin gene expression levels may not relate to C. difficile cytotoxicity or clinical severity.

Comparison of commercial assays and two-step approach to detect Clostridioides difficile in South Africa

Background

Clostridioides difficile is the number one cause of hospital-acquired diarrhoea. Accurate diagnosis of C. difficile is of utmost importance as it guides patient management and infection control practices. Studies evaluating the performance of commercially available nucleic acid amplification tests (NAATs) versus algorithms are lacking in resource-limited settings.

Objective

This study assessed the performance of three commercially available tests and a two-step approach for the diagnosis of C. difficile infection using toxigenic culture (TC) as the gold standard.

Methods

Two hundred and twenty-three non-duplicate loose stool samples were submitted to the National Health Laboratory Service Microbiology Laboratory at Tygerberg Hospital, Cape Town, South Africa, from October 2017 to October 2018. The samples were tested in parallel using the C. DIFF QUIK CHEK COMPLETE enzyme immunoassay (EIA) and two NAATs (Xpert C. difficile and BD MAX Cdiff), and the results were compared to TC. The performance of a two-step approach consisting of the C. DIFF QUIK CHEK COMPLETE followed by the Xpert C. difficile was also determined.

Results

Of 223 faecal specimens tested, 37 (16.6%) were TC-positive. The sensitivity and specificity of the C. DIFF QUIK CHEK COMPLETE were 54.1% and 98.9%; Xpert C. difficile, 86.4% and 96.8%; BD MAX Cdiff, 89.2% and 96.8%; and two-step approach, 89.2% and 96.2%.

Conclusion

The C. DIFF QUIK CHEK COMPLETE, in a two-step approach with the Xpert C. difficile, performed similarly to the NAATs on their own and offer advantages in terms of cost and workflow in low-resource settings.

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.

Characterization of the virulence of three novel clade 2 Clostridioides (Clostridium) difficile strains and a two-year screening in animals and humans in Brazil

Clostridioides (Clostridium) difficile infection (CDI) is an evolving global healthcare problem, and owing to the diverse and dynamic molecular epidemiology of C. difficile, new strains continue to emerge. In Brazil, only two cases of CDI due to the so called hypervirulent PCR ribotype (RT) 027 belonging to clade 2 have ever been reported, whereas incidence of CDI due to another “hypervirulent” RT078 (clade 5) has not yet been reported. In contrast, novel clade 2 strains have been identified in different hospitals. To better understand the epidemiology of CDIs in Brazil, this study aimed to genotypically and phenotypically characterize three novel Brazilian clade 2 strains (RT883, 884, and 885) isolated from patients with confirmed CDI. In addition, to better understand the circulating RTs, a two-year sampling was conducted in patients from the same hospital and in several domestic and wild animal species. The three strains examined showed lower production of A/B toxins than the control RT027, although two of these strains harbored a truncated tcdC gene. All strains showed swimming motility similar to that of RT027, while RT883 showed higher spore production than the reference strain. In the in vivo hamster model, the lethality of all strains was found to be similar to that of RT027. Both cgMLST and cgMLSA analyses revealed a high genetic similarity among the three-novel clade 2 isolates. In the two-year survey in animals and humans, RT883, 884, and 885 were not detected; however, three new RTs (RT988, RT989, and RT990) were isolated, two of which were genetically related to the three previously reported clade 2 strains. RT106 and RT126 were most frequently detected in humans (47.9%) and animals (57.9%), respectively. Furthermore, RT027 and RT078 were not detected in humans. The results of this study suggest that these novel clade 2 strains have virulence potential and that new strains from clade 2 continue to emerge in our setting, indicating the need for long-term local surveillance.

Application of recombinant antibodies for treatment of Clostridioides difficile infection: Current status and future perspective

Clostridioides difficile (C. difficile), known as the major cause of antibiotic-associated diarrhea, is regarded as one of the most common healthcare-associated bacterial infections worldwide. Due to the emergence of hypervirulent strains, development of new therapeutic methods for C. difficile infection (CDI) has become crucially important. In this context, antibodies have been introduced as valuable tools in the research and clinical environments, as far as the effectiveness of antibody therapy for CDI was reported in several clinical investigations. Hence, production of high-performance antibodies for treatment of CDI would be precious. Traditional approaches of antibody generation are based on hybridoma technology. Today, application of in vitro technologies for generating recombinant antibodies, like phage display, is considered as an appropriate alternative to hybridoma technology. These techniques can circumvent the limitations of the immune system and they can be exploited for production of antibodies against different types of biomolecules in particular active toxins. Additionally, DNA encoding antibodies is directly accessible in in vitro technologies, which enables the application of antibody engineering in order to increase their sensitivity and specificity. Here, we review the application of antibodies for CDI treatment with an emphasis on recombinant fragment antibodies. Also, this review highlights the current and future prospects of the aforementioned approaches for antibody-mediated therapy of CDI.

Epidemiology of Clostridium (Clostridioides) difficile Infection in Southeast Asia

This review describes the current understanding of Clostridium (Clostridioides) difficile infection (CDI) in southeast Asia regarding the prevalence of CDI, C. difficile detection methods, antimicrobial susceptibility profiles, and the potential significance of a One Health approach to prevention and control. Our initial focus had been the Indochina region, however, due to limited studies/surveillance of CDI in Indochina, other studies in southeast Asian countries and neighboring Chinese provinces are presented here for comparison. Clostridium (Clostridioides) difficile infection is one of the most common causes of hospital-acquired gastroenteritis worldwide. Since its discovery as a cause of pseudomembranous colitis in 1978, C. difficile-related disease has been more prevalent in high-income rather than low-income countries. This may be because of a lack of knowledge and awareness about the significance of C. difficile and CDI, resulting in underreporting of true rates. Moreover, the abuse of antimicrobials and paucity of education regarding appropriate usage remain important driving factors in the evolution of CDI worldwide. The combination of underreporting of true CDI rates, along with continued misuse of antimicrobial agents, poses an alarming threat for regions like Indochina. C. difficile ribotype (RT) 027 has caused outbreaks in North America and European countries, however, C. difficile RT 017 commonly occurs in Asia. Toxin A-negative/toxin B-positive (A-B+) strains of RT 017 have circulated widely and caused outbreaks throughout the world and, in southeast Asia, this strain is endemic.

Strain Variation in Clostridioides difficile Cytotoxicity Associated with Genomic Variation at Both Pathogenic and Nonpathogenic Loci

Clinical disease from Clostridioides difficile infection can be mediated by two toxins and their neighboring regulatory genes located within the five-gene pathogenicity locus (PaLoc). We provide several lines of evidence that the cytotoxicity of C. difficile may be modulated by genomic variants outside the PaLoc. We used a phylogenetic tree-based approach to demonstrate discordance between cytotoxicity and PaLoc evolutionary history, an elastic net method to show the insufficiency of PaLoc variants alone to model cytotoxicity, and a convergence-based bacterial genome-wide association study (GWAS) to identify correlations between non-PaLoc loci and changes in cytotoxicity. Combined, these data support a model of C. difficile disease wherein cytotoxicity may be strongly affected by many non-PaLoc loci. Additionally, we characterize multiple other in vitro phenotypes relevant to human infections, including germination and sporulation. These phenotypes vary greatly in their clonality, variability, convergence, and concordance with genomic variation. Finally, we highlight the intersection of loci identified by the GWAS for different phenotypes and clinical severity. This strategy to identify overlapping loci can facilitate the identification of genetic variation linking phenotypic variation to clinical outcomes. IMPORTANCE Clostridioides difficile has two major disease-mediating toxins, A and B, encoded within the pathogenicity locus (PaLoc). In this study, we demonstrate via multiple approaches that genomic variants outside the PaLoc are associated with changes in cytotoxicity. These genomic variants may provide new avenues of exploration in the hunt for novel disease-modifying interventions. Additionally, we provide insight into the evolution of several additional phenotypes also critical for clinical infection, such as sporulation, germination, and growth rate. These in vitro phenotypes display a range of responses to evolutionary pressures and, as such, vary in their appropriateness for certain bacterial genome-wide association study approaches. We used a convergence-based association method to identify the genomic variants most correlated with both changes in these phenotypes and disease severity. These overlapping loci may be important for both bacterial function and human clinical disease.