Current strategies for management of initial Clostridium difficile infection

The Stickland Reaction Precursor trans-4-Hydroxy-l-Proline Differentially Impacts the Metabolism of Clostridioides difficile and Commensal Clostridia

An intact gut microbiota confers colonization resistance against Clostridioides difficile through a variety of mechanisms, likely including competition for nutrients. Recently, proline was identified as an important environmental amino acid that C. difficile uses to support growth and cause significant disease. A posttranslationally modified form, trans-4-hydroxyproline, is highly abundant in collagen, which is degraded by host proteases in response to C. difficile toxin activity. The ability to dehydrate trans-4-hydroxyproline via the HypD glycyl radical enzyme is widespread among gut microbiota, including C. difficile and members of the commensal Clostridia, suggesting that this amino acid is an important nutrient in the host environment. Therefore, we constructed a C. difficile ΔhypD mutant and found that it was modestly impaired in fitness in a mouse model of infection, and was associated with an altered microbiota when compared to mice challenged with the wild-type strain. Changes in the microbiota between the two groups were largely driven by members of the Lachnospiraceae family and the Clostridium genus. We found that C. difficile and type strains of three commensal Clostridia had significant alterations to their metabolic gene expression in the presence of trans-4-hydroxyproline in vitro. The proline reductase (prd) genes were elevated in C. difficile, consistent with the hypothesis that trans-4-hydroxyproline is used by C. difficile to supply proline for energy metabolism. Similar transcripts were also elevated in some commensal Clostridia tested, although each strain responded differently. This suggests that the uptake and utilization of other nutrients by the commensal Clostridia may be affected by trans-4-hydroxyproline metabolism, highlighting how a common nutrient may be a signal to each organism to adapt to a unique niche. Further elucidation of the differences between them in the presence of hydroxyproline and other key nutrients will be important in determining their role in nutrient competition against C. difficile.

IMPORTANCE Proline is an essential environmental amino acid that C. difficile uses to support growth and cause significant disease. A posttranslationally modified form, hydroxyproline, is highly abundant in collagen, which is degraded by host proteases in response to C. difficile toxin activity. The ability to dehydrate hydroxyproline via the HypD glycyl radical enzyme is widespread among gut microbiota, including C. difficile and members of the commensal Clostridia, suggesting that this amino acid is an important nutrient in the host environment. We found that C. difficile and three commensal Clostridia strains had significant, but different, alterations to their metabolic gene expression in the presence of hydroxyproline in vitro. This suggests that the uptake and utilization of other nutrients by the commensal Clostridia may be affected by hydroxyproline metabolism, highlighting how a common nutrient may be a signal to each organism to adapt to a unique niche. Further elucidation of the differences between them in the presence of hydroxyproline and other key nutrients will be important to determining their role in nutrient competition against C. difficile.

The Effects of Fecal Donors with Different Feeding Patterns on Diarrhea in a Patient Undergoing Hematopoietic Stem Cell Transplantation

Almost 90% of patients undergoing hematopoietic stem cell transplantation (HSCT) experience diarrheal episodes, which represent a severe, often life-threatening complication for these patients. Although fecal microbiota transplantation (FMT) represents an alternative treatment option for infection-related diarrhea, the application of FMT in HSCT patients is greatly restricted for safety reasons. Furthermore, the therapeutic outcomes of FMT as a diarrhea treatment are somewhat related to the choice of the FMT donor. Here, we comprehensively profiled the dynamic changes in the intestinal microbiota after FMT from two donors with different feeding patterns and the same severely diarrheal recipient undergoing HSCT via a 45-day clinical observation. Importantly, no adverse events attributed to FMT were observed. The stool volume and frequency of the patient were reduced when we used feces from donor #1 (mixed feeding), but these changes were not observed after FMT from donor #2 (exclusive breastfeeding). Interestingly, no obvious differences in overall diversity (Shannon) or richness (Chao1) between the two donors were observed. Additionally, Bifidobacterium accounted for 29.9% and 18.1% of OTUs in the stools of donors #1 and #2, respectively. Lactobacillus accounted for 16.3% and 2.9% of the stools of donors #1 and #2, respectively. Furthermore, through longitudinal monitoring of the patient, we identified 6 OTUs that were particularly sensitive to the different FMT complements. Together, we present a case report suggesting that the overall diversity of the intestinal microbiota may not be the only important element in the selection of an effective FMT donor.

Frailty Predicts Morbidity and Mortality after Colectomy for Clostridium difficile Colitis

Frailty has been noted as a powerful predictive preoperative tool for 30-day postoperative complications. We sought to evaluate the association between frailty and postoperative outcomes after colectomy for Clostridium difficile colitis. The National Surgical Quality and Improvement Program cross-institutional database was used for this study. Data from 470 patients with a diagnosis of C. difficile colitis were used in the study. Modified frailty index (mFI) is a previously described and validated 11-variable frailty measure used with the National Surgical Quality and Improvement Program to assess frailty. Outcome measures included serious morbidity, overall morbidity, and Clavien IV (requiring ICU) and Clavien V (mortality) complications. The median age was 70 years and body mass index was 26.9 kg/m2. 55.6 per cent of patients were females. 98.5 per cent of patients were assigned American Society of Anesthesiologists Class III or higher. The median mFI was 0.27 (0–0.63). Because mFI increased from 0 (non-frail) to 0.55 and above, the overall morbidity increased from 53.3 per cent to 84.4 per cent and serious morbidity increased from 43.3 per cent to 78.1 per cent. The Clavien IV complication rate increased from 30.0 per cent to 75.0 per cent. The mortality rate increased from 6.7 per cent to 56.2 per cent. On a multivariate analysis, mFI was an independent predictor ofoverall morbidity (AOR: 13.0; P < 0.05), mortality (AOR: 8.8; P = 0.018), cardiopulmonary complications (AOR: 6.8; P = 0.026), and prolonged length of hospital stay (AOR: 6.6; P = 0.045). Frailty is associated with increased risk of complications in C. difficile colitis patients undergoing colectomy. mFI is an easy-to-use tool and can play an important role in the risk stratification of these patients who generally have significant morbidity and mortality to begin with.

Management of Clostridium difficile Infection in Inflammatory Bowel Disease: Expert Review from the Clinical Practice Updates Committee of the AGA Institute

The purpose of this expert review is to synthesize the existing evidence on the management of Clostridium difficile infection in patients with underlying inflammatory bowel disease. The evidence reviewed in this article is a summation of relevant scientific publications, expert opinion statements, and current practice guidelines. This review is a summary of expert opinion in the field without a formal systematic review of evidence. Best Practice Advice 1: Clinicians should test patients who present with a flare of underlying inflammatory bowel disease for Clostridium difficile infection. Best Practice Advice 2: Clinicians should screen for recurrent C difficile infection if diarrhea or other symptoms of colitis persist or return after antibiotic treatment for C difficile infection. Best Practice Advice 3: Clinicians should consider treating C difficile infection in inflammatory bowel disease patients with vancomycin instead of metronidazole. Best Practice Advice 4: Clinicians strongly should consider hospitalization for close monitoring and aggressive management for inflammatory bowel disease patients with C difficile infection who have profuse diarrhea, severe abdominal pain, a markedly increased peripheral blood leukocyte count, or other evidence of sepsis. Best Practice Advice 5: Clinicians may postpone escalation of steroids and other immunosuppression agents during acute C difficile infection until therapy for C difficile infection has been initiated. However, the decision to withhold or continue immunosuppression in inflammatory bowel disease patients with C difficile infection should be individualized because there is insufficient existing robust literature on which to develop firm recommendations. Best Practice Advice 6: Clinicians should offer a referral for fecal microbiota transplantation to inflammatory bowel disease patients with recurrent C difficile infection.

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

We investigated the increased risk of Clostridium difficile infection (CDI) caused by the combined use of antibiotics and an immunosuppressive drug in a mouse model. Our data showed that an approximate return to pretreatment conditions of gut microbiota occurred within days after cessation of the antibiotic treatment, whereas the recovery of gut microbiota was delayed with the combined treatment of antibiotics and dexamethasone, leading to an increased severity of CDI. An alteration of gut microbiota is a key player in CDI. Therefore, our data implied that immunosuppressive drugs can increase the risk of CDI through the delayed recovery of altered gut microbiota.

Diagnostic accuracy of loop-mediated isothermal amplification in detection of Clostridium difficile in stool samples: a meta-analysis

INTRODUCTION

Clostridium difficile infection (CDI) remains a diagnostic challenge for clinicians. More recently, loop-mediated isothermal amplification (LAMP) has become readily available for the diagnosis of CDI, and many studies have investigated the usefulness of LAMP for rapid and accurate diagnosis of CDI. However, the overall diagnostic accuracy of LAMP for CDI remains unclear. In this meta-analysis, our aim was to establish the overall diagnostic accuracy of LAMP in detection of Clostridium difficile (CD) in stool samples.

MATERIAL AND METHODS

A search was done in PubMed, MEDLINE, EMBASE and Cochrane Library databases up to February 2014 to identify published studies that evaluated the diagnostic role of LAMP for CD. Methodological quality was assessed according to the quality assessment for studies of diagnostic accuracy (QUADAS) instrument. The sensitivities (SEN), specificities (SPE), positive likelihood ratio (PLR), negative likelihood ratio (NLR) and diagnostic odds ratio (DOR) were pooled statistically using random effects models. Statistical analysis was performed by employing Meta-Disc 1.4 software. Summary receiver operating characteristic (SROC) curves were used to summarize overall test performance. Funnel plots were used to test the potential publication bias.

RESULT

A total of 9 studies met inclusion criteria for the present meta-analysis. The pooled SEN and SPE for diagnosing CD were 0.93 (95% CI: 0.91-0.95) and 0.98 (95% CI: 0.98-0.99), respectively. The PLR was 47.72 (95% CI: 15.10-150.82), NLR was 0.07 (95% CI: 0.04-0.14) and DOR was 745.19 (95% CI: 229.30-2421.72). The area under the ROC was 0.98. Meta-regression indicated that the total number of samples was a source of heterogeneity for LAMP in detection of CD. The funnel plots suggested no publication bias.

CONCLUSIONS

The LAMP meets the minimum desirable characteristics of a diagnostic test of SEN, SPE and other measures of accuracy in the diagnosis of CD, and it is suitable as a rapid, effective and reliable stand-alone diagnostic test for diagnosis of CDI, potentially decreasing morbidity and nosocomial spread of CD.

Preparation and preliminary application of monoclonal antibodies to the receptor binding region of Clostridium difficile toxin B

A previous nationwide Chinese epidemiological study revealed through isolation of A‑B+ Clostridium difficile strains, which produce toxin B (TcdB), but not toxin A TcdA, that the strains are widespread and more frequent in east Asian countries,. The development of a process capable of detecting TcdB is required in microbiological laboratories in order to facilitate the control of the A‑B+ C. difficile strains, however, no diagnostic reagents have been developed to date. The aim of the present study was to prepare monoclonal antibodies (mAbs) targeting the receptor binding region of TcdB (CDB3), and to establish a double‑antibody sandwich enzyme-linked immunosorbent assay (ds‑ELISA), which can be used for the diagnosis of C. difficile infection. The recombinant protein, glutathione S transferase (GST)‑CDB3 was expressed and purified using an Escherichia coli system. BALB/c mice were immunized with GST‑CDB3 recombinant protein. A hybridoma technique was used for the production of anti‑CDB3 mAb. The hybridoma clones were then screened using indirect ELISA, and anti‑CDB3 mAb was produced in the ascites of the BALB/c mice. Isotyping of anti‑CDB3 mAb was performed using an SBA Clonotyping system/horseradish peroxidase (HRP) ELISA kit. Protein G affinity chromatography was used for purification of anti‑CDB3 mAbs, and the titer and specificity of the anti‑CDB3 mAbs were assessed using indirect ELISA and western blot analysis, respectively. The ds‑ELISA was established using HRP‑labeled anti‑CDB3 mAbd, which were used to detect TcdB clinically in diarrhea stools. A total of five stable hybridoma cell clones (1E7B, 1F8D3, 2F8A6, 3B6F1 and 4A4G2) producing anti‑CDB3 mAb were established. The results of the present study indicated that the immunoglobulin (Ig)G isotype was predominant, as 1E7B2 IgG1 (λ), 2F8A6 IgG2a (κ) and 4A4G2 IgG1 (κ). In addition, the highest titer of anti‑CDB3 mAb (2F8A6 and 4A4G2) was 1:51,200. Western blotting revealed that the 2F8A6 and 4A4G2 mAbs recognized the CDB3 protein specifically. Following anti‑CDB3 mAb (4A4G2) HRP‑labeling, the optimal working concentration was confirmed to be 1:400, and the concentration of coated antibody (2F8A6) was 20 µg/ml. The sensitivity of the ds‑ELISA was 73.33% for the A+B+ toxigenic C. difficile strains, and 86.67% for the A‑B+ toxigenic C. difficile strains, with a specificity of 100% for all. In conclusion, the present study successfully developed novel mAbs specific to CDB3, and developed a ds-ELISA kit with high specificity and sensitivity for the rapid detection of TcdB. This offers a useful tool for the diagnostic assessment of TcdB.

Modeling the Context-Dependent Associations between the Gut Microbiome, Its Environment, and Host Health

Changes in the gut microbiome are often associated with disease. One of the major goals in microbiome research is determining which components of this complex system are responsible for the observed differences in health state. Most studies apply a reductionist approach, wherein individual organisms are evaluated independently of the surrounding context of the microbiome. While such methods have yielded valuable insights into the microbiome, they fail to identify patterns that may be obscured by contextual variation. A recent report by Schubert et al. [A. M. Schubert, H. Sinani, and P. D. Schloss, mBio 6(4):e00974-15, 2015, doi: 10.1128/mBio.00974-15] communicates an alternative approach to the study of the microbiome’s association with host health. By coupling a multifactored experimental design with regression modeling, the authors are able to profile context-dependent changes in the microbiome and predict health status. This work underscores the value of incorporating model-based procedures into the investigation of the microbiome and illustrates the potential clinical transformations that may arise through their use.

Recurrent Clostridium difficile infection: From colonization to cure

Clostridium difficile infection (CDI) is increasingly prevalent, dangerous and challenging to prevent and manage. Despite intense national and international attention the incidence of primary and of recurrent CDI (PCDI and RCDI, respectively) have risen rapidly throughout the past decade. Of major concern is the increase in cases of RCDI resulting in substantial morbidity, morality and economic burden. RCDI management remains challenging as there is no uniformly effective therapy, no firm consensus on optimal treatment, and reliable data regarding RCDI-specific treatment options is scant. Novel therapeutic strategies are critically needed to rapidly, accurately, and effectively identify and treat patients with, or at-risk for, RCDI. In this review we consider the factors implicated in the epidemiology, pathogenesis and clinical presentation of RCDI, evaluate current management options for RCDI and explore novel and emerging therapies.

The prospect for vaccines to prevent Clostridium difficile infection

Clostridium difficile is a spore-forming anaerobic gram-positive organism that is the leading cause of antibiotic-associated nosocomial infectious diarrhea in the Western world. This article describes the evolving epidemiology of C difficile infection (CDI) in the twenty-first century, evaluates the importance of vaccines against the disease, and defines the roles of both innate and adaptive host immune responses in CDI. The effects of passive immunotherapy and active vaccination against CDI in both humans and animals are also discussed.

Interactions Between the Gastrointestinal Microbiome and Clostridium difficile

Antibiotics have significant and long-lasting effects on the intestinal microbiota and consequently reduce colonization resistance against pathogens, including Clostridium difficile. By altering the community structure of the gut microbiome, antibiotics alter the intestinal metabolome, which includes both host- and microbe-derived metabolites. The mechanisms by which antibiotics reduce colonization resistance against C. difficile are unknown yet important for development of preventative and therapeutic approaches against this pathogen. This review focuses on how antibiotics alter the structure of the gut microbiota and how this alters microbial metabolism in the intestine. Interactions between gut microbial products and C. difficile spore germination, growth, and toxin production are discussed. New bacterial therapies to restore changes in bacteria-driven intestinal metabolism following antibiotics will have important applications for treatment and prevention of C. difficile infection.

Recovery of the gut microbiome following fecal microbiota transplantation

Clostridium difficile infection is one of the most common health care-associated infections, and up to 40% of patients suffer from recurrence of disease following standard antibiotic therapy. Recently, fecal microbiota transplantation (FMT) has been successfully used to treat recurrent C. difficile infection. It is hypothesized that FMT aids in recovery of a microbiota capable of colonization resistance to C. difficile. However, it is not fully understood how this occurs. Here we investigated changes in the fecal microbiota structure following FMT in patients with recurrent C. difficile infection, and imputed a hypothetical functional profile based on the 16S rRNA profile using a predictive metagenomic tool. Increased relative abundance of Bacteroidetes and decreased abundance of Proteobacteria were observed following FMT. The fecal microbiota of recipients following transplantation was more diverse and more similar to the donor profile than the microbiota prior to transplantation. Additionally, we observed differences in the imputed metagenomic profile. In particular, amino acid transport systems were overrepresented in samples collected prior to transplantation. These results suggest that functional changes accompany microbial structural changes following this therapy. Further identification of the specific community members and functions that promote colonization resistance may aid in the development of improved treatment methods for C. difficile infection.

IMPORTANCE

Within the last decade, Clostridium difficile infection has surpassed other bacterial infections to become the leading cause of nosocomial infections. Antibiotic use, which disrupts the gut microbiota and its capability in providing colonization resistance against C. difficile, is a known risk factor in C. difficile infection. In particular, recurrent C. difficile remains difficult to treat with standard antibiotic therapy. Fecal microbiota transplantation (FMT) has provided a successful treatment method for some patients with recurrent C. difficile infection, but its mechanism and long-term effects remain unknown. Our results provide insight into the structural and potential metabolic changes that occur following FMT, which may aid in the development of new treatment methods for C. difficile infection.

Colonic decompression and direct intraluminal medical therapy for Clostridium difficile-associated megacolon using a tube placed endoscopically in the proximal colon

AIM

Urgent colectomy for severe Clostridium difficile infection can be associated with increased morbidity and mortality. We aimed to use endoscopic methods for treatment.

METHOD

We describe a technique of placing an intracolonic tube facilitating decompression and direct delivery of vancomycin to the proximal colon along with enemas on a regular and frequent basis that may not be possible with vancomycin enemas alone.

RESULTS

Successful resolution of the C. difficile infection and avoidance of surgery.

CONCLUSION

While further long-term evaluation is required, our initial results have shown it to be effective in treating select patients with recalcitrant Clostridium difficile-associated megacolon.

Overview of Clostridium difficile infection: implications for China

The incidence and severity of Clostridium difficile infection (CDI) have dramatically increased in the Western world in recent years. In contrast, CDI is rarely reported in China, possibly due to under-diagnosis. This article briefly summarizes CDI incidence, management and preventive strategies. The authors intend to raise awareness of this disease among Chinese physicians and health workers, in order to minimize the medical and economic burden of a potential epidemic in the future.

Faecal microbiota transplantation for the treatment of recurrent Clostridium difficile infection: current promise and future needs

PURPOSE OF REVIEW

The use of faecal microbiota transplantation (FMT) as treatment for recurrent Clostridium difficile infection (CDI) has increased rapidly over the past few years. In this review, we highlight clinical studies of FMT for treatment of recurrent CDI and discuss the safety, standardization and future of this treatment option. The major risk factor for CDI is prior antibiotic use, which results in an altered state of the gut microbiota characterized by decreased microbial diversity. This altered gut microbiota increases the patient's susceptibility to CDI. In patients with recurrent CDI, the microbiota remains in a state with decreased diversity, and FMT from a healthy individual restores the gut microbiota and subsequently colonization resistance against the pathogen.

RECENT FINDINGS

Recent studies have shown the success rate for FMT as treatment for recurrent CDI being greater than 90%. Standardized, frozen preparations of faeces can be used, which increases the availability of faeces for FMT and decreases the cost of screening individual donors. In addition, there have been recent advances in identifying a defined microbial community isolated from faeces that can restore colonization resistance against C. difficile.

SUMMARY

The use of FMT is a successful treatment for recurrent CDI when primary treatment options have failed. However, more work needs to define potential long-term consequences of this treatment and understand how specific members of the gut microbiota can restore colonization resistance against C. difficile.

Clostridium difficile infection in the twenty-first century

Clostridium difficile is a spore-forming gram-positive bacillus, and the leading cause of antibiotic-associated nosocomial diarrhea and colitis in the industrialized world. With the emergence of a hypervirulent strain of C. difficile (BI/NAP1/027), the epidemiology of C. difficile infection has rapidly changed in the last decade. C. difficile infection, once thought to be an easy to treat bacterial infection, has evolved into an epidemic that is associated with a high rate of mortality, causing disease in patients thought to be low-risk. In this review, we discuss the changing face of C .difficile infection and the novel treatment and prevention strategies needed to halt this ever growing epidemic.

Human monoclonal antibodies against Clostridium difficile toxins A and B inhibit inflammatory and histologic responses to the toxins in human colon and peripheral blood monocytes

Clostridium difficile infection (CDI) is a common and debilitating nosocomial infection with high morbidity and mortality. C. difficile mediates diarrhea and colitis by releasing two toxins, toxin A and toxin B. Since both toxins stimulate proinflammatory signaling pathways in human colonocytes and both are involved in the pathophysiology of CDI, neutralization of toxin A and B activities may represent an important therapeutic approach against CDI. Recent studies indicated that human monoclonal antibodies (MAbs) against toxins A and B reduce their cytotoxic and secretory activities and prevent CDI in hamsters. Moreover, anti-toxin A and anti-toxin B MAbs together with antibiotics also effectively reduced recurrent CDI in humans. However, whether these MAbs neutralize toxin A- and toxin B-associated immune responses in human colonic mucosa or human peripheral blood monocyte cells (PBMCs) has never been examined. We used fresh human colonic biopsy specimens and peripheral blood monocytes to evaluate the effects of these antibodies against toxin A- and B-associated cytokine release, proinflammatory signaling, and histologic damage. Incubation of anti-toxin A (MK3415) or anti-toxin B (MK6072) MAbs with human PBMCs significantly inhibited toxin A- and toxin B-mediated tumor necrosis factor alpha (TNF-α) and interleukin-1β (IL-1β) expression. MK3415 and MK6072 also diminished toxin A- and toxin B-mediated NF-κB p65 phosphorylation in human monocytes, respectively, and significantly reduced toxin A- and B-induced TNF-α and IL-1β expression as well as histologic damage in human colonic explants. Our results underline the effectiveness of MK3415 and MK6072 in blocking C. difficile toxin A- and toxin B-mediated inflammatory responses and histologic damage.

Management and prevention of recurrent clostridium difficile infection in patients after total joint arthroplasty: a review

Clostridium difficile infection (CDI) is the most common infectious cause of nosocomial diarrhea in elderly patients, accounting for 15% to 25% of all cases of antibiotic-induced diarrhea in those patients. Virulent forms of this organism have developed, increasing the associated morbidity, mortality, and complication rates. The average patient undergoing total joint arthroplasty is at particular risk of CDI because of advanced age, the use of prophylactic antibiotic coverage in the perioperative period, multiple comorbid conditions, and length of hospital stay. In addition, patients who have had one CDI are at risk of another; the rate of recurrent CDI (RCDI) is 15% to 30%. To review the available information on RCDI, we conducted an extensive literature search, focusing on its epidemiology and the management strategies for its treatment and prevention. We found the management of RCDI is a controversial topic, with as yet no consensus regarding specific treatment guidelines. Several experienced clinicians have published suggested treatment algorithms, but they are based on anecdotal experience. With regard to the prevention of RCDI, the literature is scarce, and currently, the only effective strategies remain judicious use of perioperative antibiotics and appropriate implementation of infection control procedures. There are several vaccination medications that are currently being studied but are not yet ready for clinical use. We agree with the approach to management of RCDI that has been proposed in several articles, that is, on confirmation of a first recurrence of CDI by a stool toxin assay and clinical symptoms, a 14-day course of metronidazole or vancomycin; for a second recurrence, a tapered-pulsed course of vancomycin; and, for 3 or more recurrences, a repeat course of the tapered-pulsed vancomycin and adjunctive Saccharomyces boulardii or cholestyramine.

A new strategy for the prevention of Clostridium difficile infection

BACKGROUND

Clostridium difficile infection (CDI) is a leading cause of antibiotic-associated diarrhea. The infective form of C. difficile is the spore, but the vegetative bacterium causes the disease. Because C. difficile spore germination is required for symptomatic infection, antigermination approaches could lead to the prevention of CDI. We recently reported that CamSA, a bile salt analog, inhibits C. difficile spore germination in vitro.

METHODS

Mice infected with massive inocula of C. difficile spores were treated with different concentrations of CamSA and monitored for CDI signs. C. difficile spore and vegetative cells were counted in feces from infected mice.

RESULTS

A single 50-mg/kg dose of CamSA prevented CDI in mice without any observable toxicity. Lower CamSA doses resulted in delayed CDI onset and less severe signs of disease. Ingested C. difficile spores were quantitatively recovered from feces of CamSA-protected mice.

CONCLUSIONS

Our results support a mechanism whereby the antigermination effect of CamSA is responsible for preventing CDI signs. This approach represents a new paradigm in CDI treatment. Instead of further compromising the microbiota of CDI patients with strong antibiotics, antigermination therapy could serve as a microbiota surrogate to curtail C. difficile colonization of antibiotic-treated patients.