Protective antibodies against Clostridium difficile are present in intravenous immunoglobulin and are retained in humans following its administration

Case Series: Efficacy of Polyclonal Intravenous Immunoglobulin for Refractory Clostridioides difficile Infection

BACKGROUND

Intravenous immunoglobulin (IVIg) for Clostridioides difficile infection (CDI) no longer features in treatment guidelines. However, IVIg is still used by some clinicians for severe or recurrent CDI (rCDI) cases. The main objective of this study was to investigate the efficacy of IVIg and to identify possible predictors of disease resolution post IVIg administration for patients with CDI.

METHODS

This retrospective observational cohort study of patients ≥2 years old hospitalised with severe, relapsing, or rCDI treated with IVIg therapy was performed in a large UK tertiary hospital between April 2018 and March 2023. Scanned electronic notes from patient admissions and clinical reporting systems were used to collect relevant data.

RESULTS

In total, 20/978 patients diagnosed with CDI over the 5-year study were treated with IVIg. Twelve (60%) had hospital-onset CDI. Eleven of the twenty patients (55%) responded to treatment, with a mean of 8.6 (SD 10.7) days to disease resolution. Sixteen (80%) patients were treated for severe CDI and four (20%) for rCDI (n = 3) and relapsing CDI (n = 1). There were no statistically significant differences in possible independent predictors of disease resolution post IVIg administration between groups. There was an average of 6.2 (4.9) days to IVIg administration after diagnosis with no difference between responders and non-responders (p = 0.88) and no further significant difference in additional indicators. Four (36%) of the responders were immunosuppressed compared to just one (11%) of the non-responders (p = 0.15). Six of the responders (two with recurrent and four with severe CDI) improved rapidly within 2 days, and three of these were immunosuppressed.

CONCLUSION

We observed disease resolution post IVIg therapy in over 50% of patients with refractory CDI. Our data also support a potential enhanced effect of IVIg in immunosuppressed individuals. Thus, the role of IVIg for CDI treatment, particularly in the immunosuppressed, warrants future case-control studies coupled to mechanistic investigations to improve care for this ongoing significant healthcare-associated infection.

Immunization Strategies Against Clostridioides difficile

Clostridioides difficile (C. difficile) infection (CDI) is an important healthcare but also a community-associated disease. CDI is considered a public health threat and an economic burden. A major problem is the high rate of recurrences. Besides classical antibiotic treatments, new therapeutic strategies are needed to prevent infection, to treat patients, and to prevent recurrences. If fecal transplantation has been recommended to treat recurrences, another key approach is to elicit immunity against C. difficile and its virulence factors. Here, after a summary concerning the virulence factors, the host immune response against C. difficile, and its role in the outcome of disease, we review the different approaches of passive immunotherapies and vaccines developed against CDI. Passive immunization strategies are designed in function of the target antigen, the antibody-based product, and its administration route. Similarly, for active immunization strategies, vaccine antigens can target toxins or surface proteins, and immunization can be performed by parenteral or mucosal routes. For passive immunization and vaccination as well, we first present immunization assays performed in animal models and second in humans and associated clinical trials. The different studies are presented according to the mode of administration either parenteral or mucosal and the target antigens and either toxins or colonization factors.

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.

Fulminant Clostridioides difficile Infection: A Review of Treatment Options for a Life-Threatening Infection

Fulminant Clostridioides difficile infection (FCDI) encompasses 3 to 5% of all CDI cases with associated mortality rates between 30 and 40%. Major treatment modalities include surgery and medical management with antibiotic and nonantibiotic therapies. However, identification of patients with CDI that will progress to FCDI is difficult and makes it challenging to direct medical management and identify those who may benefit from surgery. Furthermore, since it is difficult to study such a critically ill population, data investigating treatment options are limited. Surgical management with diverting loop ileostomy (LI) instead of a total abdominal colectomy (TAC) with end ileostomy has several appealing advantages, and studies have not consistently demonstrated a clinical benefit with this less-invasive strategy, so both LI and TAC remain acceptable surgical options. Successful medical management of FCDI is complicated by pharmacokinetic changes that occur in critically ill patients, and there is an absence of high-quality studies that included patients with FCDI. Recommendations accordingly include a combination of antibiotics administered via multiple routes to ensure adequate drug concentrations in the colon: intravenous metronidazole, high-dose oral vancomycin, and rectal vancomycin. Although fidaxomicin is now recommended as first-line therapy for non-FCDI, there are limited clinical data to support its use in FCDI. Several nonantibiotic therapies, including fecal microbiota transplantation and intravenous immunoglobulin, have shown success as adjunctive therapies, but they are unlikely to be effective alone. In this review, we aim to summarize diagnosis and treatment options for FCDI.

A Multi-Factorial Observational Study on Sequential Fecal Microbiota Transplant in Patients with Medically Refractory Clostridioides difficile Infection

Fecal microbiota transplantation (FMT) is highly effective in recurrent Clostridioides difficile infection (CDI); increasing evidence supports FMT in severe or fulminant Clostridioides difficile infection (SFCDI). However, the multifactorial mechanisms that underpin the efficacy of FMT are not fully understood. Systems biology approaches using high-throughput technologies may help with mechanistic dissection of host-microbial interactions. Here, we have undertaken a deep phenomics study on four adults receiving sequential FMT for SFCDI, in which we performed a longitudinal, integrative analysis of multiple host factors and intestinal microbiome changes. Stool samples were profiled for changes in gut microbiota and metabolites and blood samples for alterations in targeted epigenomic, metabonomic, glycomic, immune proteomic, immunophenotyping, immune functional assays, and T-cell receptor (TCR) repertoires, respectively. We characterised temporal trajectories in gut microbial and host immunometabolic data sets in three responders and one non-responder to sequential FMT. A total of 562 features were used for analysis, of which 78 features were identified, which differed between the responders and the non-responder. The observed dynamic phenotypic changes may potentially suggest immunosenescent signals in the non-responder and may help to underpin the mechanisms accompanying successful FMT, although our study is limited by a small sample size and significant heterogeneity in patient baseline characteristics. Our multi-omics integrative longitudinal analytical approach extends the knowledge regarding mechanisms of efficacy of FMT and highlights preliminary novel signatures, which should be validated in larger studies.

Novel immunoassay for diagnosis of ongoing Clostridioides difficile infections using serum and medium enriched for newly synthesized antibodies (MENSA)

BACKGROUND

Clostridioides difficile infections (CDI) have been a challenging and increasingly serious concern in recent years. While early and accurate diagnosis is crucial, available assays have frustrating limitations.

OBJECTIVE

Develop a simple, blood-based immunoassay to accurately diagnose patients suffering from active CDI.

MATERIALS AND METHODS

Uninfected controls (N = 95) and CDI patients (N = 167) were recruited from Atlanta area hospitals. Blood samples were collected from patients within twelve days of a positive CDI test and processed to yield serum and PBMCs cultured to yield medium enriched for newly synthesized antibodies (MENSA). Multiplex immunoassays measured Ig responses to ten recombinant C. difficile antigens.

RESULTS

Sixty-six percent of CDI patients produced measurable responses to C. difficile antigens in their serum or MENSA within twelve days of a positive CDI test. Fifty-two of the 167 CDI patients (31%) were detectable in both serum and MENSA, but 32/167 (19%) were detectable only in MENSA, and 27/167 (16%) were detectable only in serum.

DISCUSSION

We describe the results of a multiplex immunoassay for the diagnosis of ongoing CDI in hospitalized patients. Our assay resolved patients into four categories: MENSA-positive only, serum-positive only, MENSA- and serum-positive, and MENSA- and serum-negative. The 30% of patients who were MENSA-positive only may be accounted for by nascent antibody secretion prior to seroconversion. Conversely, the serum-positive only subset may have been more advanced in their disease course. Immunocompromise and misdiagnosis may have contributed to the 34% of CDI patients who were not identified using MENSA or serum immunoassays.

IMPORTANCE

While there was considerable overlap between patients identified through MENSA and serum, each method detected a distinctive patient group. The combined use of both MENSA and serum to detect CDI patients resulted in the greatest identification of CDI patients. Together, longitudinal analysis of MENSA and serum will provide a more accurate evaluation of successful host humoral immune responses in CDI patients.

Diagnostic and therapy of severe Clostridioides difficile infections in the ICU

PURPOSE OF REVIEW

The purpose of the review is to provide all the recent data focusing on the diagnostic and treatment of Clostridioides difficile infection in patients admitted in the ICU.

RECENT FINDINGS

In the ICU, diagnosis remains complicated with a large number of alternative diagnosis. The treatment classically relies on vancomycin but fidaxomicin and fecal microbiota transplantation are now potential solutions in selected indications.

SUMMARY

Data on ICU-related CDI remain limited and conflicting. To date, there is no unique and simple way to obtain a diagnosis for CDI, the combination of clinical signs and a two-step testing algorithm remains the recommended gold-standard. Two molecules can be proposed for first line treatment: vancomycin and fidaxomicin. Although metronidazole may still be discussed as a treatment option for mild CDI in low-risk patients, its use for ICU-patients does not seem reasonable. Several reports suggest that fecal microbiota transplantation could be discussed, as it is well tolerated and associated with a high rate of clinical cure. CDI is a dynamic and active area of research with new diagnostic techniques, molecules, and management concepts likely changing our approach to this old disease in the near future.

Herpes simplex virus infection, Acyclovir and IVIG treatment all independently cause gut dysbiosis

Herpes simplex virus 1 (HSV) is a ubiquitous human virus resident in a majority of the global population as a latent infection. Acyclovir (ACV), is the standard of care drug used to treat primary and recurrent infections, supplemented in some patients with intravenous immunoglobulin (IVIG) treatment to suppress infection and deleterious inflammatory responses. As many diverse medications have recently been shown to change composition of the gut microbiome, we used Illumina 16S rRNA gene sequencing to determine the effects of ACV and IVIG on the gut bacterial community. We found that HSV, ACV and IVIG can all independently disrupt the gut bacterial community in a sex biased manner when given to uninfected C57BL/6 mice. Treatment of HSV infected mice with ACV or IVIG alone or together revealed complex interactions between these drugs and infection that caused pronounced sex biased dysbiosis. ACV reduced Bacteroidetes levels in male but not female mice, while levels of the Anti-inflammatory Clostridia (AIC) were reduced in female but not male mice, which is significant as these taxa are associated with protection against the development of graft versus host disease (GVHD) in hematopoietic stem cell transplant (HSCT) patients. Gut barrier dysfunction is associated with GVHD in HSCT patients and ACV also decreased Akkermansia muciniphila, which is important for maintaining gut barrier functionality. Cumulatively, our data suggest that long-term prophylactic ACV treatment of HSCT patients may contribute to GVHD and also potentially impact immune reconstitution. These data have important implications for other clinical settings, including HSV eye disease and genital infections, where ACV is given long-term.

Development of a new serological assay for the diagnosis of Clostridium difficile infections with prognostic value

PURPOSE

The most common hospital-acquired enteral infection is caused by Clostridium difficile. Unfortunately, Clostridium difficile infections (CDI) are of high risk to recur and little is known about how to predict recurrences. Previous findings have shown that high risk for recurrence correlates with low levels of C. difficile toxin-A and -B specific antibodies suggesting the protective role of humoral immunity against bacterial virulence factors. Therefore, the aim of this study was to develop an immunoassay, which specifically measures C.difficile toxin-specific antibodies in the serum that might be correlated with the risk of recurrence.

METHODS

We developed a simple ELISA to measure the quantity of toxin-A and -B-specific antibodies in human serum. The assay was then used to test anti-toxin immune response in healthy controls, in patients with primary CDI and patients with CDI recurrence.

RESULTS

The developed assay is simple, reproducible and fast. When using this test in a small clinical trial our results showed a trend toward a higher antibody level in those patients with only one episode of CDI, whereas patients with recurrent CDI had less anti-toxin A or B-specific antibodies in their serum indicating inadequate C. difficile anti-toxin immunity may facilitate recurrent infections.

CONCLUSIONS

It has already been observed that low antibody levels are associated with recurrent CDI (Bauer et al., 2014). The findings of our clinical trial show a similar trend. Our developed ELISA test could help to conduct further research and it might be helpful in clinical use to detect patients of high risk for CDI recurrence.

Management of Clostridioides (formerly Clostridium) difficile infection (CDI) in solid organ transplant recipients: Guidelines from the American Society of Transplantation Community of Practice

These updated guidelines from the American Society of Transplantation Infectious Diseases Community of Practice address the prevention and management of Clostridium difficile infection in solid organ transplant (SOT) recipients. Clostridioides (formerly Clostridium) difficile infection (CDI) is among the most common hospital acquired infections. In SOT recipients, the incidence of CDI varies by type and number or organs transplanted. While a meta-analysis of published literature found the prevalence of postoperative CDI in the general surgical population to be approximately 0.51%, the prevalence of CDI that is seen in the solid organ transplant population ranges from a low of 3.2% in the pancreatic transplant population to 12.7% in those receiving multiple organ transplants. There are no randomized, controlled trials evaluating the management of CDI in the SOT population. Herein is a review and summary of the currently available literature that has been synthesized into updated treatment guidelines for the management of CDI in the SOT population.

Management of adult Clostridium difficile digestive contaminations: a literature review

Clostridium difficile infections (CDI) dramatically increased during the last decade and cause a major public health problem. Current treatments are limited by the high disease recurrence rate, severity of clinical forms, disruption of the gut microbiota, and colonization by vancomycin-resistant enterococci (VRE). In this review, we resumed current treatment options from official recommendation to promising alternatives available in the management of adult CDI, with regard to severity and recurring or non-recurring character of the infection. Vancomycin remains the first-line antibiotic in the management of mild to severe CDI. The use of metronidazole is discussed following the latest US recommendations that replaced it by fidaxomicin as first-line treatment of an initial episode of non-severe CDI. Fidaxomicin, the most recent antibiotic approved for CDI in adults, has several advantages compared to vancomycin and metronidazole, but its efficacy seems limited in cases of multiple recurrences. Innovative therapies such as fecal microbiota transplantation (FMT) and antitoxin antibodies were developed to limit the occurrence of recurrence of CDI. Research is therefore very active, and new antibiotics are being studied as surotomycin, cadazolid, and rinidazole.

Application of Antibody-Mediated Therapy for Treatment and Prevention of Clostridium difficile Infection

Clostridium difficile causes antibiotic- and healthcare-associated diarrhea, which is characterized by a high mortality rate (5–15%) and high recurrence rate of 20% or more. Therapeutic alternatives to antibiotics are urgently needed to improve the overall cure rate. Among these, therapeutic antibodies have shown promising results in clinical studies. Herein, the authors review current monoclonal and polyclonal anti- C. difficile antibodies that have entered the clinical development stage, either for systemic administration or by the oral route. The antibodies can be applied as monotherapy or in combination with standard-of-care to treat an infection with C. difficile or to protect from a recurrence. Bezlotoxumab is the first antibody for secondary prevention of recurrence of C. difficile infection approved by the regulatory agencies in US and Europe. The human monoclonal antibody is administered systemically to patients receiving oral standard-of–care antibiotics. Other antibodies are currently in the clinical pipeline, and some are intended for oral use. They show a good safety profile, high efficacy and low production costs, and can be considered promising therapies of the future. The most promising orally administered drug candidate is a bovine antibody from hyperimmune colostral milk, which is in an advanced clinical development stage. Which antibody will enter the market is dependent on its bioavailability at the site of infection as well as its activity against C. difficile toxins, protection against colonization and possible action on spore formation. The antibody must demonstrate a clear benefit in comparison with other available treatment options to be considered for use by clinicians.

A Protein Microarray Assay for Serological Determination of Antigen-specific Antibody Responses Following Clostridium difficile Infection

We provide a detailed overview of a novel high-throughput protein microarray assay for the determination of anti-Clostridium difficile antibody levels in human sera and in separate preparations of polyclonal intravenous immunoglobulin (IVIg). The protocol describes the methodological steps involved in sample preparation, printing of arrays, assay procedure, and data analysis. In addition, this protocol could be further developed to incorporate diverse clinical samples including plasma and cell culture supernatants. We show how protein microarray can be used to determine a combination of isotype (IgG, IgA, IgM), subclass (IgG1, IgG2, IgG3, IgG4, IgA1, IgA2), and strain-specific antibodies to highly purified whole C. difficile toxins A and B (toxinotype 0, strain VPI 10463, ribotype 087), toxin B from a C. difficile toxin-B-only expressing strain (CCUG 20309), a precursor form of a B fragment of binary toxin, pCDTb, ribotype-specific whole surface layer proteins (SLPs; 001, 002, 027), and control proteins (tetanus toxoid and Candida albicans). During the experiment, microarrays are probed with sera from individuals with C. difficile infection (CDI), individuals with cystic fibrosis (CF) without diarrhea, healthy controls (HC), and from individuals pre- and post-IVIg therapy for the treatment of CDI, combined immunodeficiency disorder, and chronic inflammatory demyelinating polyradiculopathy. We encounter significant differences in toxin neutralization efficacies and multi-isotype specific antibody levels between patient groups, commercial preparations of IVIg, and sera before and following IVIg administration. Also, there is a significant correlation between microarray and enzyme-linked immunosorbent assay (ELISA) for antitoxin IgG levels in serum samples. These results suggest that microarray could become a promising tool for profiling antibody responses to C.difficile antigens in vaccinated or infected humans. With further refinement of antigen panels and a reduction in production costs, we anticipate that microarray technology may help optimize and select the most clinically useful immunotherapies for C. difficile infection in a patient-specific manner.

Quantitative Thresholds Enable Accurate Identification of Clostridium difficile Infection by the Luminex xTAG Gastrointestinal Pathogen Panel

Clostridium difficile colonizes the gastrointestinal (GI) tract, resulting in either asymptomatic carriage or a spectrum of diarrheal illness. If clinical suspicion for C. difficile is low, stool samples are often submitted for analysis by multiplex molecular assays capable of detecting multiple GI pathogens, and some institutions do not report this organism due to concerns for high false-positive rates. Since clinical disease correlates with organism burden and molecular assays yield quantitative data, we hypothesized that numerical cutoffs could be utilized to improve the specificity of the Luminex xTAG GI pathogen panel (GPP) for C. difficile infection. Analysis of cotested liquid stool samples (n = 1,105) identified a GPP median fluorescence intensity (MFI) value cutoff of ≥1,200 to be predictive of two-step algorithm (2-SA; 96.4% concordance) and toxin enzyme immunoassay (EIA) positivity. Application of this cutoff to a second cotested data set (n = 1,428) yielded 96.5% concordance. To determine test performance characteristics, concordant results were deemed positive or negative, and discordant results were adjudicated via chart review. Test performance characteristics for the MFI cutoff of ≥150 (standard), MFI cutoff of ≥1,200, and 2-SA were as follows (respectively): concordance, 95, 96, and 97%; sensitivity, 93, 78, and 90%; specificity, 95, 98, and 98%; positive predictive value, 67, 82, and 81%;, and negative predictive value, 99, 98, and 99%. To capture the high sensitivity for organism detection (MFI of ≥150) and high specificity for active infection (MFI of ≥1,200), we developed and applied a reporting algorithm to interpret GPP data from patients (n = 563) with clinician orders only for syndromic panel testing, thus enabling accurate reporting of C. difficile for 95% of samples (514 negative and 5 true positives) irrespective of initial clinical suspicion and without the need for additional testing.

Targeting Clostridium difficile Surface Components to Develop Immunotherapeutic Strategies Against Clostridium difficile Infection

New therapies are needed to prevent and treat Clostridium difficile infection and to limit the rise in antibiotic resistance. Besides toxins, several surface components have been characterized as colonization factors and have been shown as immunogenic. This review will focus on passive and active immunization strategies targeting C. difficile surface components to combat C. difficile. Concerning passive immunization, the first strategies used antisera raised against the entire bacterium to prevent infection in the hamster model. Then, surface components such as the flagellin and the S-layer proteins were used for immunization and the passive transfer of antibodies was protective in animal models. Passive immunotherapy with polyvalent immunoglobulins was used in humans and bovine immunoglobulin concentrates were evaluated in clinical trials. Concerning active immunization, vaccine assays targeting surface components were tested mainly in animal models, mouse models of colonization and hamster models of infection. Bacterial extracts, spore proteins and surface components of vegetative cells such as cell wall proteins, flagellar proteins, and polysaccharides were used as vaccine targets. Vaccine assays were performed by parenteral and mucosal routes of immunization. Both gave promising results and pave the way to development of new vaccines.

Immunization Strategies Against Clostridium difficile

C. difficile infection (CDI) is an important healthcare- but also community-associated disease. CDI is considered a public health threat and an economic burden. A major problem is the high rate of recurrences. Besides classical antibiotic treatments, new therapeutic strategies are needed to prevent infection, to treat patients and prevent recurrences. If fecal transplantation has been recommended to treat recurrences, another key approach is to restore immunity against C. difficile and its virulence factors. Here, after a summary concerning the virulence factors, the host immune response against C. difficile and its role in the outcome of disease, we review the different approaches of passive immunotherapies and vaccines developed against CDI. Passive immunization strategies are designed in function of the target antigen, the antibody-based product and its administration route. Similarly, for active immunization strategies, vaccine antigens can target toxins or surface proteins and immunization can be performed by parenteral or mucosal routes. For passive immunization and vaccination as well, we first present immunization assays performed in animal models and second in humans and associated clinical trials. The different studies are presented according to the mode of administration either parenteral or mucosal and the target antigens, either toxins or colonization factors.

Characterization of Chicken IgY Specific to Clostridium difficile R20291 Spores and the Effect of Oral Administration in Mouse Models of Initiation and Recurrent Disease

Clostridium difficile infection (CDI) are the leading cause of world-wide nosocomial acquired diarrhea. The current main clinical challenge in CDI is the elevated rate of infection recurrence that may reach up to 30% of the patients, which has been associated to the formation of dormant spores during the infection. We sought to characterize the effects of oral administration of specific anti-spore IgY in mouse models of CDI and recurrent CDI. The specificity of anti-spore IgY was evaluated in vitro. In both, initiation mouse model and recurrence mouse model, we evaluated the prophylactic and therapeutic effect of anti-spore IgY, respectively. Our results demonstrate that anti-spore IgY exhibited high specificity and titers against C. difficile spores and reduced spore adherence to intestinal cells in vitro. Administration of anti-spore IgY to C57BL/6 mice prior and during CDI delayed the appearance of the diarrhea by 1.5 day, and spore adherence to the colonic mucosa by 90%. Notably, in the recurrence model, co-administration of anti-spore IgY coupled with vancomycin delayed the appearance of recurrent diarrhea by a median of 2 days. Collectively, these observations suggest that anti-spore IgY antibodies may be used as a novel prophylactic treatment for CDI, or in combination with antibiotics to treat CDI and prevent recurrence of the infection.