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A panel of experts was convened by the Infectious Diseases Society of America (IDSA) and Society for Healthcare Epidemiology of America (SHEA) to update the 2010 clinical practice guideline on Clostridium difficile infection (CDI) in adults. The update, which has incorporated recommendations for children (following the adult recommendations for epidemiology, diagnosis, and treatment), includes significant changes in the management of this infection and reflects the evolving controversy over best methods for diagnosis. Clostridium difficile remains the most important cause of healthcare-associated diarrhea and has become the most commonly identified cause of healthcare-associated infection in adults in the United States. Moreover, C. difficile has established itself as an important community pathogen. Although the prevalence of the epidemic and virulent ribotype 027 strain has declined markedly along with overall CDI rates in parts of Europe, it remains one of the most commonly identified strains in the United States where it causes a sizable minority of CDIs, especially healthcare-associated CDIs. This guideline updates recommendations regarding epidemiology, diagnosis, treatment, infection prevention, and environmental management.

A panel of experts was convened by the Infectious Diseases Society of America (IDSA) and Society for Healthcare Epidemiology of America (SHEA) to update the 2010 clinical practice guideline on Clostridium difficile infection (CDI) in adults. The update, which has incorporated recommendations for children (following the adult recommendations for epidemiology, diagnosis, and treatment), includes significant changes in the management of this infection and reflects the evolving controversy over best methods for diagnosis. Clostridium difficile remains the most important cause of healthcare-associated diarrhea and has become the most commonly identified cause of healthcare-associated infection in adults in the United States. Moreover, C. difficile has established itself as an important community pathogen. Although the prevalence of the epidemic and virulent ribotype 027 strain has declined markedly along with overall CDI rates in parts of Europe, it remains one of the most commonly identified strains in the United States where it causes a sizable minority of CDIs, especially healthcare-associated CDIs. This guideline updates recommendations regarding epidemiology, diagnosis, treatment, infection prevention, and environmental management.

Key Points This article reviews the latest clinical and fundamental research data on the important human pathogen Clostridium difficile . The clinical aspects of C. difficile infection (CDI) that are discussed include description of the disease spectrum and severity, and the signs, symptoms and clinical pathogenesis of CDI. An overview of the available treatment options for CDI is also given, including discussion of the problems associated with each therapeutic approach and new recommendations for treatment based on disease severity and the numbers of recurrences. CDI prevention is also discussed. Prevention methods include preventing acquisition of C. difficile spores by patients (using barrier and cleaning methods) and reducing the risk of symptomatic infection if the organism is encountered, primarily by avoidance of unnecessary use of antimicrobials. The laboratory diagnosis and characterization of C. difficile is also reviewed. The main detection methods and diagnostic tests, including the recent development of molecular testing and two-step diagnostic protocols, are discussed. The main molecular typing techniques used for C. difficile and the importance of antibiotic resistance testing are described. The changing epidemiology of CDI is reviewed. Important changes in the epidemiology of CDI have been observed over the past five years, especially increased infection rates in hospitals, increased disease severity, and increased rates and mortality with patient age. Most of these changes are presumed to be driven by presence of a new epidemic strain, C. difficile BI/NAP1/027. Changes in host populations (human versus animal populations with previous low risk), a possible increase in community associated disease, and new risk factors have also been observed. The known C. difficile virulence factors (TcdA and TcdB) and newly recognized virulence factors and their role in pathogenesis are discussed. The role of antibiotics in the development of CDI is discussed in relation to the susceptibility of C. difficile to antibiotics taken by the patient. The implication of the resistance of C. difficile to the fluoroquinolone class of antibiotics, and fluoroquinolones as an increasing risk factor for CDI, are discussed. Since 2001, the prevalence and severity of Clostridium difficile infection have increased substantially, and C. difficile is now considered to be one of the most important causes of health care-associated infections. Here, Rupnik, Wilcox and Gerding discuss the recent epidemiological changes in C. difficile infection and our current knowledge of C. difficile virulence factors. Clostridium difficile is now considered to be one of the most important causes of health care-associated infections. C. difficile infections are also emerging in the community and in animals used for food, and are no longer viewed simply as unpleasant complications that follow antibiotic therapy. Since 2001, the prevalence and severity of C. difficile infection has increased significantly, which has led to increased research interest and the discovery of new virulence factors, and has expanded and focused the development of new treatment and prevention regimens. This Review summarizes the recent epidemiological changes in C. difficile infection, our current knowledge of C. difficile virulence factors and the clinical outcomes of C. difficile infection.

Key Points The most commonly prescribed antibiotic therapies for Clostridium difficile infections (CDIs), namely metronidazole and vancomycin, have a broad antibiotic spectrum and are associated with unacceptably high CDI recurrence rates Emerging CDI therapies limit further perturbation of and/or restore the gut microbiota to its pre-morbid state, reduce colonization by toxigenic strains and bolster the host immune response against C. difficile toxins As emerging narrow-spectrum CDI antibiotic therapies have limited activity against several species of enteric commensal bacteria, these new antibiotics might result in less frequent CDI recurrences Faecal microbiota transplantation is highly efficacious for preventing CDI recurrences, but questions regarding the optimal route of administration and long-term risks remain Oral administration of spores from nontoxigenic C. difficile strains could prevent CDI by preventing intestinal colonization with toxigenic strains of C. difficile Emerging immunological therapies, including monoclonal antibodies and vaccines against C. difficile toxins, might protect against symptomatic CDI and subsequent CDI recurrences Clostridium difficile infection (CDI) is one of the most common health-care-associated infections. Here, Kociolek and Gerding discuss the latest advances in the treatment and prevention of CDI, describing developments in antibiotic therapy, biotherapeutic approaches such as faecal microbiota transplantation or nontoxigenic C. difficile , and immunological approaches such as antibodies or vaccines. This Review summarizes the latest advances in the treatment and prevention of Clostridium difficile infection (CDI), which is now the most common health-care-associated infection in the USA. As traditional, standard CDI antibiotic therapies (metronidazole and vancomycin) are limited by their broad spectrum and further perturbation of the intestinal microbiota, which result in unacceptably high recurrence rates, novel therapeutic strategies for CDI are needed. Emerging CDI therapies are focused on limiting further perturbation of the intestinal microbiota and/or restoring the microbiota to its pre-morbid state, reducing colonization of the intestinal tract by toxigenic strains of C. difficile and bolstering the host immune response against C. difficile toxins. Fidaxomicin is associated with reduced CDI recurrences, and other emerging narrow-spectrum CDI antibiotic therapies might eventually demonstrate a similar benefit. Prevention of intestinal colonization of toxigenic strains of C. difficile can be achieved through restoration of the intestinal microbiota with faecal microbiota transplantation, as well as by colonizing the gut with nontoxigenic C. difficile strains. Finally, emerging immunological therapies, including monoclonal antibodies and vaccines against C. difficile toxins, might protect against CDI and subsequent CDI recurrences. The available clinical data for these emerging therapies, and their relative advantages and disadvantages, are described.

Background. Clostridium difficile infection (CDI) is a common complication of antibiotic therapy that is treated with antibiotics, contributing to ongoing disruption of the colonic microbiota and CDI recurrence. Two multinational trials were conducted to compare the efficacy of tolevamer, a nonantibiotic, toxin-binding polymer, with vancomycin and metronidazole. Methods. Patients with CDI were randomly assigned in a 2:1:1 ratio to oral tolevamer 9 g (loading dose) followed by 3 g every 8 hours for 14 days, vancomycin 125 mg every 6 hours for 10 days, or metronidazole 375 mg every 6 hours for 10 days. The primary endpoint was clinical success, defined as resolution of diarrhea and absence of severe abdominal discomfort for more than 2 consecutive days including day 10. Results. In a pooled analysis, 563 patients received tolevamer, 289 received metronidazole, and 266 received vancomycin. Clinical success of tolevamer was inferior to both metronidazole and vancomycin (P < .001), and metronidazole was inferior to vancomycin (P = .02; 44.2% [n = 534], 72.7% [n = 278], and 81.1% [n = 259], respectively). Clinical success in patients with severe CDI who received metronidazole was 66.3% compared with vancomycin, which was 78.5%. (P = .059). A post-hoc multivariate analysis that excluded tolevamer found 3 factors that were strongly associated with clinical success: vancomycin treatment, treatment-naive status, and mild or moderate CDI severity. Adverse events were similar among the treatment groups. Conclusions. Tolevamer was inferior to antibiotic treatment of CDI, and metronidazole was inferior to vancomycin. Trial Registration. clinicaltrials.gov NCT00106509 and NCT00196794.

Abstract Background Bezlotoxumab is a human monoclonal antibody against Clostridium difficile toxin B indicated to prevent C. difficile infection (CDI) recurrence (rCDI) in adults at high risk for rCDI. This post hoc analysis of pooled monocolonal antibodies for C.difficile therapy (MODIFY) I/II data assessed bezlotoxumab efficacy in participants with characteristics associated with increased risk for rCDI. Methods The analysis population was the modified intent-to-treat population who received bezlotoxumab or placebo (n = 1554) by risk factors for rCDI that were prespecified in the statistical analysis plan: age ≥65 years, history of CDI, compromised immunity, severe CDI, and ribotype 027/078/244. The proportion of participants with rCDI in 12 weeks, fecal microbiota transplant procedures, 30-day all cause and CDI-associated hospital readmissions, and mortality at 30 and 90 days after randomization were presented. Results The majority of enrolled participants (75.6%) had ≥1 risk factor; these participants were older and a higher proportion had comorbidities compared with participants with no risk factors. The proportion of placebo participants who experienced rCDI exceeded 30% for each risk factor compared with 20.9% among those without a risk factor, and the rCDI rate increased with the number of risk factors (1 risk factor: 31.3%; ≥3 risk factors: 46.1%). Bezlotoxumab reduced rCDI, fecal microbiota transplants, and CDI-associated 30-day readmissions in participants with risk factors for rCDI. Conclusions The risk factors prespecified in the MODIFY statistical analysis plan are appropriate to identify patients at high risk for rCDI. While participants with ≥3 risk factors had the greatest reduction of rCDI with bezlotoxumab, those with 1 or 2 risk factors may also benefit. Clinical Trials Registration NCT01241552 (MODIFY I) and NCT01513239 (MODIFY II). Subgroup analyses from MODIFY confirmed that prior Clostridium difficile infection (CDI), age ≥65 years, infection with 027/078/244 strain, compromised immunity, and severe CDI are risk factors for recurrent CDI. Bezlotoxumab reduced CDI recurrence in participants with ≥1 risk factor compared with placebo.

Prompt and precise diagnosis is an important aspect of effective management of Clostridium difficile infection (CDI). CDI causes 15%–25% of all cases of antibiotic-associated diarrhea, the severity of which ranges from mild diarrhea to fulminant pseudomembranous colitis. Several factors, especially advanced age and hospitalization, should be considered in the diagnosis of CDI. In particular, nosocomial diarrhea arising >72 hours after admission among patients receiving antibiotics is highly likely to have resulted from CDI. Testing of stool for the presence of C. difficile toxin confirms the diagnosis of CDI. However, performance of an enzyme immunoassay is the usual method by which CDI is confirmed, but this test appears to be relatively insensitive, compared with the cell cytotoxicity assay and stool culture for toxigenic C. difficile on selective medium. Endoscopy and computed tomography are less sensitive than stool toxin assays but may be useful when immediate results are important or other confounding conditions rank high in the differential diagnosis. Often overlooked aspects of this diagnosis are high white blood cell counts (which are sometimes in the leukemoid range) and hypoalbuminemia.

Background Effective treatment options for recurrent Clostridioides difficile infection (rCDI) are limited, with high recurrence rates associated with the current standard of care. Herein we report results from an open-label Phase 2 trial to evaluate the safety, efficacy, and durability of RBX2660—a standardized microbiota-based investigational live biotherapeutic—and a closely-matched historical control cohort. Methods This prospective, multicenter, open-label Phase 2 study enrolled patients who had experienced either ≥ 2 recurrences of CDI, treated by standard-of-care antibiotic therapy, after a primary CDI episode, or ≥ 2 episodes of severe CDI requiring hospitalization. Participants received up to 2 doses of RBX2660 rectally administered with doses 7 days apart. Treatment success was defined as the absence of CDI diarrhea without the need for retreatment for 8 weeks after completing study treatment. A historical control group with matched inclusion and exclusion criteria was identified from a retrospective chart review of participants treated with standard-of-care antibiotics for recurrent CDI who matched key criteria for the study. The primary objective was to compare treatment success of RBX2660 to the historical control group. A key secondary outcome was the safety profile of RBX2660, including adverse events and CDI occurrence through 24 months after treatment. In addition, fecal samples from RBX2660-treated participants were sequenced to evaluate microbiome composition and functional changes from before to after treatment. Results In this Phase 2 open-label clinical trial, RBX2660 demonstrated a 78.9% (112/142) treatment success rate compared to a 30.7% (23/75) for the historical control group (p < 0.0001; Chi-square test). Post-hoc analysis indicated that 91% (88/97) of evaluable RBX2660 responders remained CDI occurrence-free to 24 months after treatment demonstrating durability. RBX2660 was well-tolerated with mostly mild to moderate adverse events. The composition and diversity of RBX2660 responders’ fecal microbiome significantly changed from before to after treatment to become more similar to RBX2660, and these changes were durable to 24 months after treatment. Conclusions In this Phase 2 trial, RBX2660 was safe and effective for reducing rCDI recurrence as compared to a historical control group. Microbiome changes are consistent with restorative changes implicated in resisting C. difficile recurrence. Clinical Trials Registration NCT02589847 (10/28/2015)

The ability to grow as a biofilm can facilitate survival of bacteria in the environment and promote infection. To better characterize biofilm formation in the pathogen Clostridium difficile, we established a colony biofilm culture method for this organism on a polycarbonate filter, and analyzed the matrix and the cells in biofilms from a variety of clinical isolates over several days of biofilm culture. We found that biofilms readily formed in all strains analyzed, and that spores were abundant within about 6 days. We also found that extracellular DNA (eDNA), polysaccharide and protein was readily detected in the matrix of all strains, including the major toxins A and/or B, in toxigenic strains. All the strains we analyzed formed spores. Apart from strains 630 and VPI10463, which sporulated in the biofilm at relatively low frequencies, the frequencies of biofilm sporulation varied between 46 and 65%, suggesting that variations in sporulation levels among strains is unlikely to be a major factor in variation in the severity of disease. Spores in biofilms also had reduced germination efficiency compared to spores obtained by a conventional sporulation protocol. Transmission electron microscopy revealed that in 3 day-old biofilms, the outermost structure of the spore is a lightly staining coat. However, after 6 days, material that resembles cell debris in the matrix surrounds the spore, and darkly staining granules are closely associated with the spores surface. In 14 day-old biofilms, relatively few spores are surrounded by the apparent cell debris, and the surface-associated granules are present at higher density at the coat surface. Finally, we showed that biofilm cells possess 100-fold greater resistance to the antibiotic metronidazole then do cells cultured in liquid media. Taken together, our data suggest that C. difficile cells and spores in biofilms have specialized properties that may facilitate infection.