Stool Interleukin-1ß Differentiates Clostridioides difficile Infection (CDI) From Asymptomatic Carriage and Non-CDI Diarrhea.

BACKGROUND: Despite advances in the understanding and diagnosis of Clostridioides difficile infection (CDI), clinical distinction within the colonization-infection continuum remains an unmet need. METHODS: By measuring stool cytokines and antitoxin antibodies in well-characterized cohorts of CDI (diarrhea, nucleic acid amplification test [NAAT] positive), non-CDI diarrhea (NCD; diarrhea, NAAT negative), asymptomatic carriers (ASC; no diarrhea, NAAT positive) and hospital controls (CON; no diarrhea, NAAT negative), we aim to discover novel biological markers to distinguish between these cohorts. We also explore the relationship of these stool cytokines and antitoxin antibody with stool toxin concentrations and disease severity. RESULTS: Stool interleukin (IL) 1ß, stool immunoglobulin A (IgA), and immunoglobulin G (IgG) anti-toxin A had higher (P < .0001) concentrations in CDI (n = 120) vs ASC (n = 43), whereas toxins A, B, and fecal calprotectin did not. Areas under the receiver operating characteristic curve (ROC-AUCs) for IL-1ß, IgA, and IgG anti-toxin A were 0.88, 0.83, and 0.83, respectively. A multipredictor model including IL-1ß and IgA anti-toxin A achieved an ROC-AUC of 0.93. Stool IL-1ß concentrations were higher in CDI compared to NCD (n = 75) (P < .0001) and NCD + ASC+ CON (CON, n = 75) (P < .0001), with ROC-AUCs of 0.83 and 0.86, respectively. Stool IL-1ß had positive correlations with toxins A (ρA = +0.55) and B (ρB = +0.49) in CDI (P < .0001) but not in ASC (P > .05). CONCLUSIONS: Stool concentrations of the inflammasome pathway, proinflammatory cytokine IL-1ß, can accurately differentiate CDI from asymptomatic carriage and NCD, making it a promising biomarker for CDI diagnosis. Significant positive correlations exist between stool toxins and stool IL-1ß in CDI but not in asymptomatic carriers.

Fecal Mycobiota Combined With Host Immune Factors Distinguish Clostridioides difficile Infection From Asymptomatic Carriage.

BACKGROUND & AIMS: Although the role of gut microbiota in Clostridioides difficile infection (CDI) has been well established, little is known about the role of mycobiota in CDI. Here, we performed mycobiome data analysis in a well-characterized human cohort to evaluate the potential of using gut mycobiota features for CDI diagnosis. METHODS: Stool samples were collected from 118 hospital patients, divided into 3 groups: CDI (n = 58), asymptomatic carriers (Carrier, n = 28), and Control (n = 32). The nuclear ribosomal DNA internal transcribed spacer 2 was sequenced using the Illumina HiSeq platform to assess the fungal composition. Downstream statistical analyses (including Alpha diversity analysis, ordination analysis, differential abundance analysis, fungal correlation network analysis, and classification analysis) were then performed. RESULTS: Significant differences were observed in alpha and beta diversity between patients with CDI and Carrier (P < .05). Differential abundance analysis identified 2 genera (Cladosporium and Aspergillus) enriched in Carrier. The ratio of Ascomycota to Basidiomycota was dramatically higher in patients with CDI than in Carrier and Control (P < .05). Correlations between host immune factors and mycobiota features were weaker in patients with CDI than in Carrier. Using 4 fungal operational taxonomic units combined with 6 host immune markers in the random forest classifier can achieve very high performance (area under the curve ∼92.38%) in distinguishing patients with CDI from Carrier. CONCLUSIONS: Our study provides specific markers of stool fungi combined with host immune factors to distinguish patients with CDI from Carrier. It highlights the importance of gut mycobiome in CDI, which may have been underestimated. Further studies on the diagnostic applications and therapeutic potentials of these findings are warranted.

Anemia Etiology and the Response to a Gluten-Free Diet in Untreated Patients With Celiac Disease: A 2-Year Follow-Up.

INTRODUCTION: Anemia and micronutrient deficiencies are common in newly diagnosed patients with celiac disease (CeD). We aim to determine the prevalence and etiology of anemia in a cohort of patients with CeD in the United States and examine the effect of a gluten-free diet (GFD) on the laboratory parameters related to anemia in CeD. METHODS: We analyzed a prospectively collected cohort of adults with biopsy-proven CeD followed in a specialized CeD center between January 2000 and June 2016. We used the level of hemoglobin (Hb) and micronutrients suggested by the World Health Organization to establish the diagnosis of anemia or deficiencies. Demographic data and laboratory parameters related to anemia and micronutrients were recorded at the time of diagnosis and on a GFD. A celiac expert nutritionist or gastroenterologist evaluated all patients. RESULTS: In 572 patients with laboratory evaluation before starting a GFD, approximately 25% presented with anemia at the time of diagnosis of CeD. Iron deficiency was present in 50.8% of the cohort and in 78.8% of the patients with anemia. Within the anemic population, 84.4% of female patients as compared with 58.3% of male patients ( P = 0.02) showed iron deficiency. Folate deficiency (23.2%), vitamin B12 deficiency (11%), and anemia of chronic diseases (7.8%) were also part of both sexes' anemia etiology. Of the initially anemic patients, 81% and 89% normalized their Hb levels within 1 year and 2 years of beginning a GFD, respectively. All patients received appropriate supplementation when needed. DISCUSSION: Approximately 25% of individuals have anemia at CeD diagnosis. The anemia etiology included iron deficiency, vitamin deficiencies, and anemia of chronic diseases. Most of the patients will normalize their Hb levels and the anemia laboratory parameters 1 year after starting a strict GFD.

EUS imaging for the diagnosis of nonalcoholic fatty liver disease.

BACKGROUND AND AIMS: EUS is increasingly used to evaluate patients with liver disease, but its role in assessing hepatic steatosis has not been reported. The goal of our study was to assess the accuracy of EUS for diagnosing hepatic steatosis. METHODS: We identified all patients who underwent EUS-guided liver biopsy sampling at our institution. All digitally stored EUS liver images were reviewed by a single radiologist, who rated the severity of liver echogenicity using a 4-point US scale. Liver biopsy specimens for all study patients were reviewed by a single liver pathologist, who rated them for steatosis and fibrosis using Nonalcoholic Steatohepatitis Clinical Research Network criteria. Receiver operator characteristic curves were used to assess the diagnostic accuracy of EUS for hepatic steatosis for all patients and in a subgroup analysis for obese and nonobese patients. RESULTS: During the study period, 76 patients underwent EUS-guided liver biopsy sampling. The average age of study patients was 56.5 years, 50% were women, and 43.2% were obese. The accuracy for EUS for the diagnosis of hepatic steatosis was .8 (95% confidence interval [CI], .7-.89). The accuracy of EUS for the diagnosis of hepatic steatosis in obese patients was .93 (95% CI, .8-.99) and in nonobese patients was .69 (95% CI, .54-.83). For obese patients, EUS had a positive predictive value of 89.7% and a negative predictive value of 75%. The finding of course echotexture on EUS had an accuracy of 79% for the diagnosis of grade 3 fibrosis or cirrhosis. CONCLUSIONS: EUS is a useful tool for the diagnosis of hepatic steatosis, particularly in obese patients in whom abdominal US has modest accuracy.

Proton pump inhibitors and risk of Clostridium difficile infection: association or causation?

PURPOSE OF REVIEW: The rising burden of Clostridium difficile infection (CDI) requires urgent identification of preventable risk factors. Observational studies suggest an association between proton-pump inhibitor (PPI) use and CDI risk. RECENT FINDINGS: Key historical literature on PPI and CDI associations is reviewed as a prelude to evaluating the plausibility of a causative association. Impactful literature from the past 18 months is examined in detail and critically appraised through the lens of the Bradford Hill Criteria for determination of causality. The PPI and CDI association has been studied extensively and is valid. Nonetheless, causality is not proven due to extensive and difficult to control confounding in observational studies of CDI patient populations with complex comorbidities. SUMMARY: In the authors' opinion, systematic discontinuation of PPIs in patients at risk for CDI is not warranted based on current evidence. Well controlled prospective human studies are needed. Careful and repeated consideration should be given to all PPI prescriptions to avoid potential adverse effects.

Patients with celiac disease have a lower prevalence of non-insulin-dependent diabetes mellitus and metabolic syndrome.

BACKGROUND & AIMS: We investigated whether risk for non-insulin-dependent diabetes mellitus (NIDDM) and metabolic syndrome are affected by celiac disease. We examined the prevalence of NIDDM and metabolic syndrome among adults with celiac disease, compared with matched controls. METHODS: We assessed medical records of 840 patients with biopsy-proven celiac disease for diagnoses of NIDDM, hypertension, or hyperlipidemia; body mass index (BMI); lipid profile; and levels of glucose or glycosylated hemoglobin, to identify those with metabolic syndrome. Patients without celiac disease were matched for age, sex, and ethnicity (n = 840 controls). The prevalence of NIDDM and metabolic syndrome in the celiac disease cohort was compared with that of the controls and subjects included in the National Health and Nutrition Examination Survey. RESULTS: Twenty-six patients with celiac disease (3.1%) had NIDDM compared with 81 controls (9.6%) (P < .0001). Similarly, the prevalence of metabolic syndrome was significantly lower among patients with celiac disease than controls (3.5% vs 12.7%; P < .0001). The mean BMI of patients with celiac disease was significantly lower than that of controls (24.7 vs 27.5; P < .0001). However, celiac disease was still associated with a lower risk of NIDDM, after controlling for BMI. CONCLUSIONS: The prevalence of NIDDM and metabolic syndrome are lower among patients with celiac disease than in matched controls and the general population. These differences are not explained by differences in BMI. Studies are needed to determine the mechanisms by which celiac disease affects the risk for NIDDM and metabolic syndrome.

Best Practices in the Management of Clostridioides difficile Infection in Developing Nations.

Clostridioides difficile infection (CDI) is a well-known cause of hospital-acquired infectious diarrhea in developed countries, though it has not been a top priority in the healthcare policies of developing countries. In the last decade, several studies have reported a wide range of CDI rates between 1.3% and 96% in developing nations, raising the concern that this could represent a healthcare threat for these nations. This review defines developing countries as those with a human development index (HDI) below 0.8. We aim to report the available literature on CDI epidemiology, diagnostics, management, and prevention in developing countries. We identify limitations for CDI diagnosis and management, such as limited access to CDI tests and unavailable oral vancomycin formulation, and identify opportunities to enhance CDI care, such as increased molecular test capabilities and creative solutions for CDI. We also discuss infection prevention strategies, including antimicrobial stewardship programs and opportunities emerging from the COVID-19 pandemic, which could impact CDI care.

Understanding host immune responses in Clostridioides difficile infection: Implications for pathogenesis and immunotherapy.

Clostridioides difficile (C. difficile) is the predominant causative agent of nosocomial diarrhea worldwide. Infection with C. difficile occurs due to the secretion of large glycosylating toxin proteins, which can lead to toxic megacolon or mortality in susceptible hosts. A critical aspect of C. difficile's biology is its ability to persist asymptomatically within the human host. Individuals harboring asymptomatic colonization or experiencing a single episode of C. difficile infection (CDI) without recurrence exhibit heightened immune responses compared to symptomatic counterparts. The significance of these immune responses cannot be overstated, as they play critical roles in the development, progression, prognosis, and outcomes of CDI. Nonetheless, our current comprehension of the immune responses implicated in CDI remains limited. Therefore, further investigation is imperative to elucidate their underlying mechanisms. This review explores recent advancements in comprehending CDI pathogenesis and how the host immune system response influences disease progression and severity, aiming to enhance our capacity to develop immunotherapy-based treatments for CDI.

Rational Design of Live Biotherapeutic Products for the Prevention of Clostridioides difficile Infection.

Clostridioides difficile infection (CDI) is one of the leading causes of healthcare- and antibiotic-associated diarrhea. While fecal microbiota transplantation (FMT) has emerged as a promising therapy for recurrent CDI, its exact mechanisms of action and long-term safety are not fully understood. Defined consortia of clonal bacterial isolates, known as live biotherapeutic products (LBPs), have been proposed as an alternative therapeutic option. However, the rational design of LBPs remains challenging. Here, we employ a computational pipeline and three independent metagenomic datasets to systematically identify microbial strains that have the potential to inhibit CDI. We first constructed the CDI-related microbial genome catalog, comprising 3,741 non-redundant metagenome-assembled genomes (nrMAGs) at the strain level. We then identified multiple potential protective nrMAGs that can be candidates for the design of microbial consortia targeting CDI, including strains from Dorea formicigenerans, Oscillibacter welbionis, and Faecalibacterium prausnitzii. Importantly, some of these potential protective nrMAGs were found to play an important role in the success of FMT, and the majority of the top protective nrMAGs can be validated by various previously reported findings. Our results demonstrate a computational framework for the rational selection of microbial strains targeting CDI, paving the way for the computational design of microbial consortia against other enteric infections.

Analysis of Intestinal Mycobiota of Patients with Clostridioides difficile Infection among a Prospective Inpatient Cohort.

Clostridioides difficile infection (CDI) is a burden to health care systems worldwide. Gut microbiota dysbiosis associated with CDI has been well accepted. However, contribution of fungal mycobiota to CDI has recently gained research interest. Here, we report the gut mycobiota composition of 149 uniquely well characterized participants from a prospective clinical cohort and evaluate the discriminating ability of gut mycobiota to classify CDI and non-CDI patients. Fecal samples were divided into two groups: (i) CDI (inpatients who had clinically significant diarrhea and positive nucleic acid amplification testing [NAAT] and received subsequent CDI therapy, n = 58) and (ii) non-CDI, which can be further divided into three subgroups: (a) carrier (inpatients with positive stool NAAT but without diarrhea; n = 28); (b) diarrhea (inpatients with negative stool NAAT; n = 31); and (c) control (inpatients with negative stool NAAT and without diarrhea; n = 32). Fecal mycobiota composition was analyzed by internal transcribed spacer 2 (ITS2) sequencing. In comparison to non-CDI patients, CDI patients tend to have gut mycobiota with lower biodiversity, weaker fungi correlations, and weaker correlations between fungi and host immune factors. Notably, 11 genera (Saccharomyces, Penicillium, Aspergillus, Cystobasidium, Cladosporium, and so on) were significantly enriched in non-CDI patients, and Pichia and Suhomyces were enriched in patients with CDI, while 1 two genera, Cystobasidium and Exophiala, had higher abundance in patients with diarrhea compared with CDI (linear discriminant analysis [LDA] > 3.0; P < 0.05). Ascomycota and Basidiomycota (or Candida and Saccharomyces) exhibited a strong negative correlation (r ≤ -0.714 or r ≤ -0.387; P < 0.05), and the ratios of Ascomycota to Basidiomycota or genera Candida to Saccharomyces were dramatically higher in CDI patients than in non-CDI patients (P < 0.05). A disease-specific pattern with much weaker fungal abundance correlations was observed in the CDI group compared to that in the non-CDI and diarrhea groups, suggesting that these correlations may contribute to the development of CDI. Our findings provided specific markers of stool fungi that distinguish CDI from all non-CDI hospitalized patients. This study's potential clinical utility for better CDI diagnosis warrants further investigation. IMPORTANCE Clostridioides difficile is an opportunistic bacterial pathogen that causes a serious and potentially life-threatening infection of the human gut. It remains an existing challenge to distinguish active infection of CDI from diarrhea with non-CDI causes. A few large prospective studies from recent years suggest that there is no single optimal test for the diagnosis of CDI. Previous research has concentrated on the relationship between bacteria and CDI, while the roles of fungi, as a significant proportion of the gut microbial ecosystem, remain understudied. In this study, we report a series of fungal markers that may add diagnostic values for the development of a more systematic approach to accurate CDI diagnosis. These results help open the door for better understanding of the relationship between host immune factors and the fungal community in the context of CDI pathogenesis.

Clostridium difficile toxins induce VEGF-A and vascular permeability to promote disease pathogenesis.

Clostridium difficile infection (CDI) is mediated by two major exotoxins, toxin A (TcdA) and toxin B (TcdB), that damage the colonic epithelial barrier and induce inflammatory responses. The function of the colonic vascular barrier during CDI has been relatively understudied. Here we report increased colonic vascular permeability in CDI mice and elevated vascular endothelial growth factor A (VEGF-A), which was induced in vivo by infection with TcdA- and/or TcdB-producing C. difficile strains but not with a TcdA-TcdB- isogenic mutant. TcdA or TcdB also induced the expression of VEGF-A in human colonic mucosal biopsies. Hypoxia-inducible factor signalling appeared to mediate toxin-induced VEGF production in colonocytes, which can further stimulate human intestinal microvascular endothelial cells. Both neutralization of VEGF-A and inhibition of its signalling pathway attenuated CDI in vivo. Compared to healthy controls, CDI patients had significantly higher serum VEGF-A that subsequently decreased after treatment. Our findings indicate critical roles for toxin-induced VEGF-A and colonic vascular permeability in CDI pathogenesis and may also point to the pathophysiological significance of the gut vascular barrier in response to virulence factors of enteric pathogens. As an alternative to pathogen-targeted therapy, this study may enable new host-directed therapeutic approaches for severe, refractory CDI.

Bezlotoxumab: anti-toxin B monoclonal antibody to prevent recurrence of Clostridium difficile infection.

INTRODUCTION: Clostridium difficile infection (CDI) is the most common nosocomial infection in the U.S. 25% of CDI patients go on to develop recurrent CDI (rCDI) following current standard of care (SOC) therapy, leading to morbidity, mortality and economic loss. The first passive immunotherapy drug targeting C.difficile toxin B (bezlotoxumab) has been approved recently by the FDA and EMA for prevention of rCDI. Areas covered: A body of key studies was selected and reviewed by the authors. The unmet needs in CDI care were ascertained with emphasis in rCDI, including the epidemiology, pathophysiology and current management. The current knowledge about the immune response to C. difficile toxins and how this knowledge led to the development and the clinical use of bezlotoxumab is described. Current and potential future competitors to the drug were examined. Expert commentary: A single 10 mg/kg intravenous infusion of bezlotoxumab has been shown to decrease rCDI by ~40% (absolute reduction ~10%) in patients being treated for primary CDI or rCDI with SOC antibiotics. Targeting C.difficile toxins by passive immunotherapy is a novel mechanism for prevention of C.difficile infection. Bezlotoxumab will be a valuable adjunctive therapy to reduce the burden of CDI.