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Recurrence of Clostridium difficile infection (CDI) occurs in approximately 25% of successfully treated patients. Two phase 3 randomized, double-blind trials were conducted at 154 sites in the United States, Canada, and Europe to compare fidaxomicin vs vancomycin in treating CDI. Patients with CDI received fidaxomicin 200 mg twice daily or vancomycin 125 mg 4 times daily for 10 days. The primary end point was clinical cure of CDI at end of treatment, and a secondary end point was recurrence during the 28 days following clinical cure. In all, 1164 subjects were enrolled, of which a subgroup of 128 in the per-protocol population had another recent episode of CDI prior to the CDI diagnosis at study enrollment. In the analysis of this subgroup, initial response to therapy was similar for both drugs (>90% cure). However, recurrence within 28 days occurred in 35.5% of patients treated with vancomycin and 19.7% of patients treated with fidaxomicin (-15.8% difference; 95% confidence interval, -30.4% to -0.3%; P = .045). Early recurrence (within 14 days) was reported in 27% of patients treated with vancomycin and 8% of patients treated with fidaxomicin (P = .003). In patients with a first recurrence of CDI, fidaxomicin was similar to vancomycin in achieving a clinical response at end of therapy but superior in preventing a second recurrence within 28 days. Clinical Trials Registration. NCT00314951 and NCT00468728.

Epsilon toxin (Etx), a potent pore forming toxin (PFT) produced by Clostridium perfringens , is responsible for the pathogenesis of enterotoxaemia of ruminants and has been suggested to play a role in multiple sclerosis in humans. Etx is a member of the aerolysin family of β-PFTs (aβ-PFTs). While the Etx soluble monomer structure was solved in 2004, Etx pore structure has remained elusive due to the difficulty of isolating the pore complex. Here we show the cryo-electron microscopy structure of Etx pore assembled on the membrane of susceptible cells. The pore structure explains important mutant phenotypes and suggests that the double β-barrel, a common feature of the aβ-PFTs, may be an important structural element in driving efficient pore formation. These insights provide the framework for the development of novel therapeutics to prevent human and animal infections, and are relevant for nano-biotechnology applications. Epsilon toxin (Etx) is a potent pore forming toxin (PFT) produced by Clostridium perfringens. Here authors show the cryo-EM structure of the Etx pore assembled on the membrane of susceptible cells and shed light on pore formation and mutant phenotypes.

The microflora-sparing properties of fidaxomicin were examined during the conduct of a randomized clinical trial comparing vancomycin 125 mg 4 times per day versus fidaxomicin 200 mg twice per day for 10 days as treatment of Clostridium difficile infection (CDI). Fecal samples were obtained from 89 patients (45 received fidaxomicin, and 44 received vancomycin) at study entry and on days 4, 10, 14, 21, 28, and 38 for quantitative cultures for C. difficile and cytotoxin B fecal filtrate concentrations. Additionally, samples from 10 patients, each receiving vancomycin or fidaxomicin, and 10 samples from healthy controls were analyzed by quantitative real-time polymerase chain reaction with multiple group-specific primers to evaluate the impact of antibiotic treatment on the microbiome. Compared with controls, patients with CDI at study entry had counts of major microbiome components that were 2—3-log 10 colony-forming units (CFU)/g lower. In patients with CDI, fidaxomicin allowed the major components to persist, whereas vancomycin was associated with a further 2—4-log 10 CFU reduction of Bacteroides/Prevotella group organisms, which persisted to day 28 of the study, and shorter term and temporary suppression of both Clostridium coccoides and Clostridium leptum group organisms. In the posttreatment period, C. difficile counts similarly persisted in both study populations, but reappearance of toxin in fecal filtrates was observed in 28% of vancomycin-treated patient samples (29 of 94), compared with 14% of fidaxomicin-treated patient samples (13 of 91; P = .03). Similarly, 23% of vancomycin-treated patients (10 of 44) and 11% of fidaxomicin-treated patients (5 of 44) had recurrence of CDI. Whereas vancomycin and fidaxomicin are equally effective in resolving CDI symptoms, preservation of the microflora by fidaxomicin is associated with a lower likelihood of CDI recurrence. Clinical Trials Registration. NTC00314951.

Background. An epidemic strain of Clostridium difficile designated by restriction endonuclease analysis (REA) as group BI has caused multiple outbreaks of severe C. difficile infection (CDI). The treatment response of patients infected with this strain is uncertain. Methods. Clostridium difficile isolates were collected from 2 phase 3 clinical trials comparing fidaxomicin to vancomycin and typed using REA. Clinical cure and recurrence outcomes were analyzed by strain type of the infecting organism, BI and non-BI, using both univariate and multivariate analyses. Results. From 999 patients, 719 isolates were available for typing (356 fidaxomicin treated and 363 vancomycin treated). BI was the most common REA group (34% of isolates). Patients infected with BI had lower cure rates (86.6%; 214 of 247) than those infected with non-BI strains (94.3%; 445 of 472) (P < .001). The cure rate difference between the BI and non-BI patients was significant for both vancomycin (P = .02) and fidaxomicin (P = .007). BI patients had a recurrence rate of 27.4% (51 of 186), compared with a recurrence rate of 16.6% (66 of 397) in non-BI patients (P = .002). By multivariate analysis, BI infection was statistically significant as a risk factor for reduced cure (odds ratio [OR], 0.48; 95% confidence interval [CI], .27—.85; P = .030) and for increased recurrence (OR, 1.57; 95% CI, 1.01—2.45; P = .046). Conclusions. The clinical cure rate of patients infected with the epidemic BI C. difficile strain is lower than the cure rate of those infected with non-BI strains whether treated with fidaxomicin or vancomycin. Similarly, the CDI recurrence rate is increased in patients with the BI strain compared with patients with other C. difficile strains.

The hospital environment is a reservoir for the transmission of microorganisms. The effect of improved cleaning on patient-centred outcomes remains unclear. We aimed to evaluate the effectiveness of an environmental cleaning bundle to reduce health care-associated infections in hospitals. The REACH study was a pragmatic, multicentre, randomised trial done in 11 acute care hospitals in Australia. Eligible hospitals had an intensive care unit, were classified by the National Health Performance Authority as a major hospital (public hospitals) or having more than 200 inpatient beds (private hospitals), and had a health-care-associated infection surveillance programme. The stepped-wedge design meant intervention periods varied from 20 weeks to 50 weeks. We introduced the REACH cleaning bundle, a multimodal intervention, focusing on optimising product use, technique, staff training, auditing with feedback, and communication, for routine cleaning. The primary outcomes were incidences of health-care-associated Staphylococcus aureus bacteraemia, Clostridium difficile infection, and vancomycin-resistant enterococci infection. The secondary outcome was the thoroughness of cleaning of frequent touch points, assessed by a fluorescent marking gel. This study is registered with the Australian and New Zealand Clinical Trial Registry, number ACTRN12615000325505. Between May 9, 2016, and July 30, 2017, we implemented the cleaning bundle in 11 hospitals. In the pre-intervention phase, there were 230 cases of vancomycin-resistant enterococci infection, 362 of S aureus bacteraemia, and 968 C difficile infections, for 3 534 439 occupied bed-days. During intervention, there were 50 cases of vancomycin-resistant enterococci infection, 109 of S aureus bacteraemia, and 278 C difficile infections, for 1 267 134 occupied bed-days. After the intervention, vancomycin-resistant enterococci infections reduced from 0·35 to 0·22 per 10 000 occupied bed-days (relative risk 0·63, 95% CI 0·41–0·97, p=0·0340). The incidences of S aureus bacteraemia (0·97 to 0·80 per 10 000 occupied bed-days; 0·82, 0·60–1·12, p=0·2180) and C difficile infections (2·34 to 2·52 per 10 000 occupied bed-days; 1·07, 0·88–1·30, p=0·4655) did not change significantly. The intervention increased the percentage of frequent touch points cleaned in bathrooms from 55% to 76% (odds ratio 2·07, 1·83–2·34, p<0·0001) and bedrooms from 64% to 86% (1·87, 1·68–2·09, p<0·0001). The REACH cleaning bundle was successful at improving cleaning thoroughness and showed great promise in reducing vancomycin-resistant enterococci infections. Our work will inform hospital cleaning policy and practice, highlighting the value of investment in both routine and discharge cleaning practice. National Health and Medical Research Council (Australia).

Our study sought to compare the strain types of Clostridium difficile causing initial and recurrent episodes of C. difficile infection (CDI) in adult patients with a first episode of CDI or 1 prior episode of CDI within the previous 90 days. Strains originated from patients who had been entered into two phase 3 randomized clinical trials of fidaxomicin versus vancomycin. Isolates of C. difficile from the initial and recurrent episodes within 28 (±2) days of cure of CDI were compared using restriction endonuclease analysis (REA) typing. Paired isolates were available from 90 of 194 (46%) patients with recurrent CDI. Patients with isolates available were significantly younger (P = .008) and more likely to be from Canadian sites (P = .0001), compared with patients without isolates. In 75 of 90 subjects (83.3%), the identical REA type strain was identified at recurrence and the initial episode (putative relapse). Early recurrences (0—14 days after treatment completion) were relapses in 86.7% and a new strain (reinfection) in 13.3%. Later recurrences (15—31 days after treatment) were relapses in 76.7% and reinfections in 23.3%. Mean time (± standard deviation) to recurrence was 12.2 (±6.4) days for relapses and 14.7 (±6.8) days for reinfections (P = .177). The most common BI/NAP1/027 group and the previous US epidemic REA group J/NAP2/001 had a significantly higher combined rate of recurrence with the same strain (relapse), compared with the other REA groups (39 of 42 [93%] vs 36 of 48 [75%], respectively; P = .023). We found a higher than historic rate of recurrent CDI caused by the same isolate as the original episode, a finding that may be related to the relatively short observation period in this study and the high frequency of isolation of epidemic strains, such as groups BI and J, for which relapse rates may be higher than for other REA groups. Caution in generalizing these observations is required, because the patients studied were younger and more likely to be from Canadian sites than were patients with recurrence who did not provide isolates. Clinical Trials Registration. NCT00314951 and NCT00468728.

Clostridium species cause several local and systemic diseases. Conventional identification of these microorganisms is in part laborious, not always reliable, time consuming or does not always distinguish different species, i.e., C. botulinum and C. sporogenes. All in, there is a high interest to find out a reliable, powerful and rapid method to identify Clostridium spp. not only on genus but also on species level. The aim of the present study was to identify Clostridium spp. strains and also to find differences and metabolic groups of C. botulinum by Matrix-Assisted Laser Desorption/Ionization Time of Flight Mass Spectrometry (MALDI-TOF MS). A total of 123 strains of Clostridium spp. (C. botulinum, n = 40, C. difficile, n = 11, C. tetani, n = 11, C. sordellii, n = 20, C. sporogenes, n = 18, C. innocuum, n = 10, C. perfringens, n = 13) were analyzed by MALDI-TOF MS in combination with methods of multivariate statistical analysis. MALDI-TOF MS analysis in combination with methods of multivariate statistical analysis was able to discriminate between the different tested Clostridium spp., even between species which are closely related and difficult to differentiate by traditional methods, i.e., C. sporogenes and C. botulinum. Furthermore, the method was able to separate the different metabolic groups of C. botulinum. Especially, E gene-positive C. botulinum strains are clearly distinguishable from the other species but also from those producing other toxin types. Thus, MALDI-TOF MS represents a reliable and above all quick method for identification of cultivated Clostridium species.

Background. Patients with recurrent Clostridium difficile infection (CDI) have a > 60% risk of relapse, as conventional therapies do not address the underlying gastrointestinal dysbiosis. This exploratory study evaluated the safety and efficacy of bacterial spores for preventing recurrent CDI. Methods. Stool specimens from healthy donors were treated with ethanol to eliminate pathogens. The resulting spores were fractionated and encapsulated for oral delivery as SER-109. Following their response to standard-of-care antibiotics, patients in cohort 1 were treated with SER-109 on 2 consecutive days (geometric mean dose, 1.7 × 10⁹ spores), and those in cohort 2 were treated on 1 day (geometric mean dose, 1.1 × 10⁸ spores). The primary efficacy end point was absence of C. difficile-positive diarrhea during an 8-week follow-up period. Microbiome alterations were assessed. Results. Thirty patients (median age, 66.5 years; 67% female) were enrolled, and 26 (86.7%) met the primary efficacy end point. Three patients with early, self-limiting C. difficile-positive diarrhea did not require antibiotics and tested negative for C. difficile at 8 weeks; thus, 96.7% (29 of 30) achieved clinical resolution. In parallel, gut microbiota rapidly diversified, with durable engraftment of spores and no outgrowth of non-spore-forming bacteria found after SER-109 treatment. Adverse events included mild diarrhea, abdominal pain, and nausea. Conclusions. SER-109 successfully prevented CDI and had a favorable safety profile, supporting a novel microbiome-based intervention as a potential therapy for recurrent CDI.

The impact of probiotics on dogs with acute hemorrhagic diarrhea syndrome (AHDS) has not been evaluated so far. The study aim was to assess the effect of probiotic treatment on the clinical course, intestinal microbiome, and toxigenic Clostridium perfringens in dogs with AHDS in a prospective, placebo-controlled, blinded trial. Twenty-five dogs with AHDS with no signs of sepsis were randomly divided into a probiotic (PRO; Visbiome, ExeGi Pharma) and placebo group (PLAC). Treatment was administered for 21 days without antibiotics. Clinical signs were evaluated daily from day 0 to day 8. Key bacterial taxa, C. perfringens encoding NetF toxin and enterotoxin were assessed on days 0, 7, 21. Both groups showed a rapid clinical improvement. In PRO a significant clinical recovery was observed on day 3 (p = 0.008), while in PLAC it was observed on day 4 (p = 0.002) compared to day 0. Abundance of Blautia (p<0.001) and Faecalibacterium (p = 0.035) was significantly higher in PRO on day 7 compared to day 0, while in PLAC the abundance of Faecalibacterium was not significantly higher on any study day and Blautia (p = 0.016) was only significantly higher on day 21 compared to day 0. Abundance of C. perfringens was significantly lower on day 7 (p = 0.011) compared to day 0 in PRO but not in PLAC. Enterotoxin genes were significantly lower in PRO on day 21 (p = 0.028) compared to PLAC. Fecal samples of 57% of all dogs were positive for netF toxin genes on day 0 and the abundance was significantly lower on day 7 compared to day 0 in PRO (p = 0.016) and PLAC (p = 0.031). The probiotic treatment was associated with an accelerated normalization of the intestinal microbiome. Dogs with aseptic AHDS showed a rapid decrease of netF toxin genes and fast clinical recovery in both groups under symptomatic treatment without antibiotics.

The pathogenesis of Clostridium difficile, the major cause of antibiotic-associated diarrhea, is mainly associated with the production and activities of two major toxins. In many bacteria, toxins are released into the extracellular environment via the general secretion pathways. C. difficile toxins A and B have no export signature and their secretion is not explainable by cell lysis, suggesting that they might be secreted by an unusual mechanism. The TcdE protein encoded within the C. difficile pathogenicity locus (PaLoc) has predicted structural features similar to those of bacteriophage holin proteins. During many types of phage infection, host lysis is driven by an endolysin that crosses the cytoplasmic membrane through a pore formed by holin oligomerization. We demonstrated that TcdE has a holin-like activity by functionally complementing a λ phage deprived of its holin. Similar to λ holin, TcdE expressed in Escherichia coli and C. difficile formed oligomers in the cytoplamic membrane. A C. difficile tcdE mutant strain grew at the same rate as the wild-type strain, but accumulated a dramatically reduced amount of toxin proteins in the medium. However, the complemented tcdE mutant released the toxins efficiently. There was no difference in the abundance of tcdA and tcdB transcripts or of several cytoplasmic proteins in the mutant and the wild-type strains. In addition, TcdE did not overtly affect membrane integrity of C. difficile in the presence of TcdA/TcdB. Thus, TcdE acts as a holin-like protein to facilitate the release of C. difficile toxins to the extracellular environment, but, unlike the phage holins, does not cause the non-specific release of cytosolic contents. TcdE appears to be the first example of a bacterial protein that releases toxins into the environment by a phage-like system.