A Detrimental Role of Immunosuppressive Drug, Dexamethasone, During Clostridium difficile Infection in Association with a Gastrointestinal Microbial Shift

Gut Microbiome in Patients after Heart Transplantation-Current State of Knowledge

The human gut microbiota include over 10 trillion microorganisms, such as bacteria, fungi, viruses, archaea, and protozoa. Many reports indicate the strong correlation between dysbiosis and the severity of cardiovascular diseases. Microbiota seem to interact with the host's alloimmunity and may have an immunomodulatory role in graft rejection processes. In our study, we present the current state of the knowledge of microbiota in heart transplant recipients. We present up-to-date microbiota diagnostic methods, interactions between microbiota and immunosuppressive drugs, the immunomodulatory effects of dysbiosis, and the available strategies (experimental and clinical strategies) to modulate host microbiota.

Association Between Immunosuppressive Therapy and Outcome of Clostridioides difficile Infection: Systematic Review and Meta-Analysis

BACKGROUND

Patients with Clostridioides difficile infection (CDI) often have coexisting medical problems requiring immunosuppressive therapy. However, limited data are available on the association between immunosuppressive therapy and CDI outcomes.

AIM

To determine the association between immunosuppressive therapy and CDI outcomes.

METHODS

PubMed, Embase, and Cochrane Library were searched through February 2021. Two reviewers independently reviewed and included studies that compared adult CDI patients who received immunosuppressive therapy to those who did not. The primary outcome was complicated CDl, including death, surgery, shock, or ICU admission. Raw data or unadjusted odds ratios (ORs) were used to calculate pooled ORs with 95% confidence intervals (CIs).

RESULTS

Twenty-two studies with a total of 5759 CDI patients were selected. Immunosuppressive therapy was significantly associated with both primary outcome and death, with pooled ORs of 1.61 (95% CI 1.33-1.96) and 1.73 (95% CI 1.39-2.15) separately. The association between corticosteroids and primary outcome was also significant with OR of 1.73 (95% CI 1.41, 2.12). In subgroup analysis, the factors explaining differences in study results included study quality, patient age, and whether individual studies had adjusted for potential confounders. In a systematic review, most studies suggested a positive association between immunosuppressive therapy and complicated outcomes of CDI in patients comorbid for IBD.

CONCLUSIONS

Our systematic review and meta-analysis demonstrate that immunosuppressive therapy is a risk factor for complicated outcomes of CDI.

Immunosuppressive therapy after solid organ transplantation and the gut microbiota: Bidirectional interactions with clinical consequences

Our understanding of the involvement of the gut microbiota (GM) in human health has expanded exponentially over the last few decades, particularly in the fields of metabolism, inflammation, and immunology. Immunosuppressive treatment (IST) prescribed to solid organ transplant (SOT) recipients produces GM changes that affect these different processes. This review aims at describing the current knowledge of how IST changes the GM. Overall, SOT followed by IST results in persistent changes in the GM, with a consistent increase in proteobacteria including opportunistic pathobionts. In mice, Tacrolimus induces dysbiosis and metabolic disorders, and alters the intestinal barrier. The transfer of the GM from Tacrolimus-treated hosts confers immunosuppressive properties, suggesting a contributory role for the GM in this drug's efficacy. Steroids induce dysbiosis and intestinal barrier alterations, and also seem to depend partly on the GM for their immunosuppressive and metabolic effects. Mycophenolate Mofetil, frequently responsible for digestive side effects such as diarrhea and colitis, is associated with pro-inflammatory dysbiosis and increased endotoxemia. Alemtuzumab, m-TOR inhibitors, and belatacept have shown more marginal impact on the GM. Most of these observations are descriptive. Future studies should explore the underlying mechanism of IST-induced dysbiosis in order to better understand their efficacy and safety characteristics.

Impact of superimposed Clostridium difficile infection in Crohn's or ulcerative colitis flares in the outpatient setting

PURPOSE

The prospective assessment of Clostridium difficile infection (CDI) impact in inflammatory bowel disease (IBD) flare in outpatient setting has been poorly investigated. We aimed to evaluate the prevalence and the associated factors with CDI in IBD outpatients presenting colitis flares as well as the outcomes following treatment.

METHODS

In this prospective cohort study, conducted from October, 2014, to July, 2016, 120 IBD patients (55% presenting colitis flare) and 40 non-IBD controls were assessed for CDI. Multivariate regression analysis was performed to identify predictors of CDI. Outcome analysis was estimated for recurrent CDI, hospitalization, colectomy, and CDI-associated mortality.

RESULTS

The number of patients with CDI was significantly higher in IBD patients experiencing flares than in both inactive IBD and non-IBD groups (28.8 vs. 5.6 vs. 0%, respectively; p = 0.001). Females (OR = 1.39, 95% CI, 1.13-17.18), younger age (OR = 0.77, 95% CI, 0.65-0.92), steroid treatment (OR = 7.42, 95% CI, 5.17-40.20), and infliximab therapy (OR = 2.97, 95% CI, 1.99-24.63) were found to be independently associated with CDI. There was a dose-related increase in the risks of CDI on patients which had taken prednisone. Those treated with vancomycin had a satisfactory response to therapy, but 21% presented recurrent CDI and 16% were hospitalized. Neither necessity of colectomy nor mortality was noticed in any patient during the investigation.

CONCLUSIONS

In IBD outpatients presenting colitis flares, CDI is highly prevalent. Females, younger age, infliximab, and notably steroid therapy were independently associated with CDI. Most patients with CDI experienced mild-to-moderate disease, and prompt treatment with vancomycin was highly effective, which seems to reduce the serious complication risks.

Clostridioides difficile Biology: Sporulation, Germination, and Corresponding Therapies for C. difficile Infection

Clostridioides difficile is a Gram-positive, spore-forming, toxin-producing anaerobe, and an important nosocomial pathogen. Due to the strictly anaerobic nature of the vegetative form, spores are the main morphotype of infection and transmission of the disease. Spore formation and their subsequent germination play critical roles in C. difficile infection (CDI) progress. Under suitable conditions, C. difficile spores will germinate and outgrow to produce the pathogenic vegetative form. During CDI, C. difficile produces toxins (TcdA and TcdB) that are required to initiate the disease. Meanwhile, it also produces spores that are responsible for the persistence and recurrence of C. difficile in patients. Recent studies have shed light on the regulatory mechanisms of C. difficile sporulation and germination. This review is to summarize recent advances on the regulation of sporulation/germination in C. difficile and the corresponding therapeutic strategies that are aimed at these important processes.

Factors Associated with the Use of Fecal Microbiota Transplant in Patients with Recurrent Clostridium difficile Infections

OBJECTIVE To identify the factors associated with first Clostridium difficile infection (CDI) that predict fecal microbiota transplantation (FMT) for recurrent CDI DESIGN We carried out a retrospective single-center cohort study to compare the clinical characteristics of 200 patients who underwent FMT for recurrent CDI to 75 patients who did not. SETTING A single academic hospital in the United States PATIENTS Adult patients RESULTS The time from first to second CDI correlated to subsequent FMT use. Concomitant inflammatory bowel disease (IBD; P=.002), use of immunosuppressive therapy (P=.04), and use of metronidazole within 2 months before the first CDI (P=.02) correlated positively to subsequent FMT in univariate analysis. The use of oral vancomycin for first CDI was more common in those who required FMT than those who did not in univariate (P=.02) and multivariate (P=.03) analyses. In contrast, intravenous vancomycin use within 2 months before the first CDI reduced the risk for FMT in univariate P=.000003) and multivariate (P=.0001) analyses. Black patients with recurrent CDI were less likely to receive FMT than white patients (P=.00005). Patients who received FMT were also less likely to have comorbidities. CONCLUSIONS This study provides important insights into the factors predictive for FMT in patients with recurrent CDI and highlights the potential racial and medical characteristics that affect the access of the patients to FMT. Infect Control Hosp Epidemiol 2018;39:302-306.

Intestinal microbiome and permeability in patients with autoimmune hepatitis

Autoimmune hepatitis (AIH) is a severe inflammatory liver disease. The underlying mechanisms remain unclear, but recent studies provided new perspectives on altered intestinal microbiome and permeability in AIH animal models and patients, highlighting gut-liver crosstalk in the pathogenesis of AIH. Transgenic AIH mice carrying HLA-DR3 showed reduced diversity and total load of gut microbiota. Germ-free mice are resistant to concanavalin A-induced liver injury, whereas enterogenouss antigens induce the activation of natural killer T cells participating in concanavalin A-induced liver injury, supporting the close relationship between microbiota and AIH. Moreover, 'molecular mimicry' provides a plausible interpretation of the immune reactions between microorganic antigens and liver autoantigens, for instance, cytochrome P4502D6, the target of cross-reactivity between virus and self. Nevertheless, direct evidence for the intestinal microbiome and permeability in AIH is still limited. The relationship between AIH susceptibilities and an intestinal microbiome shaped by drugs, diets or genes needs further study.

Blueberry Phenolics Reduce Gastrointestinal Infection of Patients with Cerebral Venous Thrombosis by Improving Depressant-Induced Autoimmune Disorder via miR-155-Mediated Brain-Derived Neurotrophic Factor

Cerebral venous thrombosis (CVT) often causes human depression, whereas depression-induced low immunity makes the patients susceptible to gastrointestinal infection. Blueberry possesses antidepressant properties which may improve autoimmunity and reduce gastrointestinal infection. Brain-derived neurotrophic factor (BDNF) performs antidepressant function and can be regulated by miR-155, which may be affected by blueberry. To explore the possible molecular mechanism, blueberry compounds were analyzed by high-performance liquid chromatography. Activity of compounds was tested by using HT22 cells. The present study tested 124 patients with CVT-induced mild-to-moderate depressive symptoms (Center for Epidemiologic Studies—Depression Scale [CES-D] ≥16) and gastrointestinal infection. Patients were randomly assigned to blueberry extract group (BG, received 10 mg blueberry extract daily) and placebo group (PG, received 10 mg placebo daily). After 3 months, depression, gastrointestinal infection and lipid profiles were investigated. Serum miR-155 and BDNF were measured using real-time quantitative polymerase chain reaction and or Western Blot. Blueberry treatment improved depressive symptoms and lipid profiles, and also reduced gastrointestinal infection in the BG group (P < 0.05) but those of the PG group (P = 1). These changes were paralleled by increase in serum levels of BDNF and miR-155 (P < 0.05). HPLC analysis showed that blueberry extracts were the main phenolic acids with 0.18, 0.85, 0.26, 0.72, 0.66, 0.4,1, and 1.92 mg/g of gentisic acid, chlorogenic acid, [2]-epicatechin, p-coumaric acid, benzoic acid, p-anisic acid, and quercetin in blueberry extracts, respectively. Phenolics in blueberry are possible causal agents in improving antidepressant activity and reducing gastrointestinal infection. Administration of blueberry increased BDNF expression and miR-155. Blueberry cannot affect BDNF level when miR-155 is overexpressed or inhibited. Phenolics from blueberry reduced gastrointestinal infection of patients with CVT by improving antidepressant activity via upregulation of miR-155-mediated BDNF.

Molecular, microbiological and clinical characterization of Clostridium difficile isolates from tertiary care hospitals in Colombia

In Colombia, the epidemiology and circulating genotypes of Clostridium difficile have not yet been described. Therefore, we molecularly characterized clinical isolates of C.difficile from patients with suspicion of C.difficile infection (CDI) in three tertiary care hospitals. C.difficile was isolated from stool samples by culture, the presence of A/B toxins were detected by enzyme immunoassay, cytotoxicity was tested by cell culture and the antimicrobial susceptibility determined. After DNA extraction, tcdA, tcdB and binary toxin (CDTa/CDTb) genes were detected by PCR, and PCR-ribotyping performed. From a total of 913 stool samples collected during 2013-2014, 775 were included in the study. The frequency of A/B toxins-positive samples was 9.7% (75/775). A total of 143 isolates of C.difficile were recovered from culture, 110 (76.9%) produced cytotoxic effect in cell culture, 100 (69.9%) were tcdA+/tcdB+, 11 (7.7%) tcdA-/tcdB+, 32 (22.4%) tcdA-/tcdB- and 25 (17.5%) CDTa+/CDTb+. From 37 ribotypes identified, ribotypes 591 (20%), 106 (9%) and 002 (7.9%) were the most prevalent; only one isolate corresponded to ribotype 027, four to ribotype 078 and four were new ribotypes (794,795, 804,805). All isolates were susceptible to vancomycin and metronidazole, while 85% and 7.7% were resistant to clindamycin and moxifloxacin, respectively. By multivariate analysis, significant risk factors associated to CDI were, staying in orthopedic service, exposure to third-generation cephalosporins and staying in an ICU before CDI symptoms; moreover, steroids showed to be a protector factor. These results revealed new C. difficile ribotypes and a high diversity profile circulating in Colombia different from those reported in America and European countries.

Changes in Composition of the Gut Bacterial Microbiome after Fecal Microbiota Transplantation for Recurrent Clostridium difficile Infection in a Pediatric Heart Transplant Patient

The microbiome is increasingly recognized as an important influence on human health and many of the comorbidities that affect patients after solid organ transplantation (SOT) have been shown to involve changes in gut bacterial populations. Thus, microbiome changes in an individual patient may have important health implications after SOT but this area remains understudied. We describe changes in the composition of the fecal microbiome from a pediatric heart transplant recipient before and >2.5 years after he underwent repeated fecal microbiota transplantation (FMT) for recurrent Clostridium difficile infection (CDI). With both documented episodes of CDI, there was marked loss of bacterial diversity with overgrowth of Proteobacteria (>98.9% of phyla identified) associated with symptomatic colitis that was corrected after FMT. We hypothesize that a second CDI occurring after FMT was related to incomplete restoration of normal bowel flora post-FMT with relative deficiencies of the phyla Firmicutes and Bacteroidetes and the families Lachnospiraceae and Ruminococcaceae. Following the second FMT, there was a gradual shift in gut bacterial composition coincident with the recipient developing lymphonodular hyperplasia of the colon and painless hematochezia that resolved with discontinuation of mycophenolate mofetil (MMF). This case documents dynamic changes in the bacterial microbiome after FMT and suggests that MMF may influence the gut microbiome with consequences for the patient.