Therapy for Clostridium difficile infection – any news beyond Metronidazole and Vancomycin?

Inhibition of spores to prevent the recurrence of Clostridioides difficile infection - A possibility or an improbability?

Clostridioides difficile is one of the most common nosocomial gastrointestinal pathogens, and recurrence is a problematic issue because approximately 20-30% of patients experience at least one episode of recurrence, even after treatment with a therapeutic drug of choice for C. difficile infection (CDI), such as vancomycin. CDI recurrence has a multifactorial complex mechanism, in which gut microbiota disruption coincident with viable C. difficile spores, is considered the most important factor. The effectiveness of an anti-C. difficile antimicrobial agent against CDI cannot guarantee its inhibitory effect on C. difficile spores and vice versa. However, an antimicrobial agent, such as fidaxomicin, which has a good inhibitory effect on both C. difficile vegetative cells and spores is assumed to not only treat CDI but also prevent its recurrence. Prolonged adherence to the exosporium has been proposed as a possible mechanism of inhibiting spores, and as a result, redesigning anti-C. difficile antimicrobial agents with the ability to adhere to the exosporium may provide another pathway for the development of anti-C. difficile spore agents. For example, vancomycin lacks an inhibitory effect against C. difficile spores, but a vancomycin-loaded spore-targeting iron oxide nanoparticle that selectively binds to C. difficile spores has been developed to successfully delay spore germination. Some new antimicrobial agents in phase II clinical trials, including cadazolid and ridinilazole, have shown exceptional anti-C. difficile and spore-inhibiting effects that can be expected to not only treat CDI but also prevent its recurrence in the future.

Characteristics and predictors of treatment failure with intravenous tigecycline monotherapy among adult patients with severe Clostridioides (Clostridium) difficile infection: a single-centre observational cohort study

Our aim was to analyze characteristics of treatment failure with intravenous tigecycline monotherapy among adults with severe Clostridioides (Clostridium) difficile infection (CDI). A single-centre observational cohort study was performed between 2014 and 2018. Data were collected by charts review, diagnosis and severity were determined by ESCMID guidelines. Primary outcome was treatment failure, secondary outcomes were in-hospital mortality, relapse, colectomy, and complication rates. Independent predictors of failure were identified using logistic regression. Altogether 110 patients were included, failure occurred in 37.3%. Patients with failure frequently had chronic heart and pulmonary co-morbidities, peritonitis, higher CRP levels, ICU admittance rates and need for total parenteral nutrition and vasopressors. Mostly, CDI-specific mortality and complications contributed to failure. Relapse rates were similar. Chronic pulmonary disease, ileus, total parenteral nutrition, and duration of tigecycline therapy were predictors of failure. We conclude that severe CDI cases with higher risk for tigecycline monotherapy failure might be identified by contributing factors.

Mechanism of Antibacterial Activity of Bacillus amyloliquefaciens C-1 Lipopeptide toward Anaerobic Clostridium difficile

Probiotics may offer an attractive alternative for standard antibiotic therapy to treat Clostridium difficile infections (CDI). In this study, the antibacterial mechanism in vitro of newly isolated B. amyloliquefaciens C-1 against C. difficile was investigated. The lipopeptides surfactin, iturin, and fengycin produced by C-1 strongly inhibited C. difficile growth and viability. Systematic research of the bacteriostatic mechanism showed that the C-1 lipopeptides damage the integrity of the C. difficile cell wall and cell membrane. In addition, the lipopeptide binds to C. difficile genomic DNA, leading to cell death. Genome resequencing revealed many important antimicrobial compound-encoding clusters, including six nonribosomal peptides (surfactins (srfABCD), iturins (ituABCD), fengycins (fenABCDE), bacillibactin (bmyABC), teichuronic, and bacilysin) and three polyketides (bacillaene (baeEDLMNJRS), difficidin (difABCDEFGHIJ), and macrolactin (mlnABCDEFGHI)). In addition, there were other beneficial genes, such as phospholipase and seven siderophore biosynthesis gene clusters, which may contribute synergistically to the antibacterial activity of B. amyloliquefaciens C-1. We suggest that proper application of antimicrobial peptides may be effective in C. difficile control.

Multiple-Ascending-Dose Phase 1 Clinical Study of the Safety, Tolerability, and Pharmacokinetics of CRS3123, a Narrow-Spectrum Agent with Minimal Disruption of Normal Gut Microbiota

CRS3123 is a novel small molecule that potently inhibits methionyl-tRNA synthetase of Clostridioides difficile, inhibiting C. difficile toxin production and spore formation. CRS3123 has been evaluated in a multiple-ascending-dose placebo-controlled phase 1 trial. Thirty healthy subjects, ages 18 to 45 years, were randomized into three cohorts of 10 subjects each, receiving either 200, 400, or 600 mg of CRS3123 (8 subjects per cohort) or placebo (2 subjects per cohort) by oral administration twice daily for 10 days. CRS3123 was generally safe and well tolerated, with no serious adverse events (SAEs) or severe treatment-emergent adverse events (TEAEs) reported. All subjects completed their assigned treatment and follow-up visits, and there were no trends in systemic, vital sign, or laboratory TEAEs. There were no QTcF interval changes or any clinically significant changes in other electrocardiogram (ECG) intervals or morphology. CRS3123 showed limited but detectable systemic uptake; although absorption increased with increasing dose, the increase was less than dose proportional. Importantly, the bulk of the oral dose was not absorbed, and fecal concentrations were substantially above the MIC90 value of 1 μg/ml at all dosages tested. Subjects receiving either of the two lower doses of CRS3123 exhibited minimal disruption of normal gut microbiota after 10 days of twice-daily dosing. CRS3123 was inactive against important commensal anaerobes, including Bacteroides, bifidobacteria, and commensal clostridia. Microbiome data showed favorable differentiation compared to other CDI therapeutics. These results support further development of CRS3123 as an oral agent for the treatment of CDI. (This study has been registered at Clinicaltrials.gov under identifier NCT02106338.).

Initial therapy affects duration of diarrhoea in critically ill patients with Clostridioides difficile infection (CDI)

Background

Critically ill patients in the intensive care unit (ICU) are at high risk for developing Clostridioides difficile infections (CDI). Risk factors predicting their mortality or standardized treatment recommendations have not been defined for this cohort. Our goal is to determine outcome and mortality associated risk factors for patients at the ICU with CDI by evaluating clinical characteristics and therapy regimens.

Methods

A retrospective single-centre cohort study. One hundred forty-four patients (0.4%) with CDI-associated diarrhoea were included (total 36.477 patients admitted to 12 ICUs from January 2010 to September 2015). Eight patients without specific antibiotic therapy were excluded, so 132 patients were analysed regarding mortality, associated risk factors and therapy regimens using univariate and multivariate regression.

Results

Twenty-eight-day mortality was high in patients diagnosed with CDI (27.3%) compared to non-infected ICU patients (9%). Patients with non CDI-related sepsis (n = 40/132; 30.3%) showed further increase in 28-day mortality (45%; p = 0.003). Initially, most patients were treated with a single CDI-specific agent (n = 120/132; 90.9%), either metronidazole (orally, 35.6%; or IV, 37.1%) or vancomycin (18.2%), or with a combination of antibiotics (n = 12/132; 9.1%). Patients treated with metronidazole IV showed significantly longer duration of diarrhoea > 5 days (p = 0.006). In a multivariate regression model, metronidazole IV as initial therapy was an independent risk factor for delayed clinical cure. Immunosuppressants (p = 0.007) during ICU stay lead to increased 28-day mortality.

Conclusion

Treatment of CDI with solely metronidazole IV leads to a prolonged disease course in critically ill patients.

Stool cultures at the ICU: get rid of it!

Background

Stool cultures for Campylobacter, Salmonella and Shigella and/or Yersinia spp. are frequently ordered in critically ill patients with diarrhea. The aim of this study is to analyze the diagnostic yield in a large cohort of critically ill patients. Therefore, we performed a cohort study at the Department of Intensive Care Medicine of a University Hospital (11 ICUs).

Results

From all patients who were admitted to the ICU between 2010 and 2015, stool cultures were taken from 2.189/36.477 (6%) patients due to diarrhea. Results of all stool cultures tested for Campylobacter, Salmonella and Shigella and/or Yersinia spp. were analyzed. Overall, 5.747 tests were performed; only six were positive (0.1%). In four of these, Campylobacter spp. were detected; diarrhea started within 48 h after ICU admission. Two patients with Salmonella spp. detection were chronic shedders. On the contrary, testing for Clostridium difficile via GDH- and toxin A/B-EIA yielded positive results in 179/2209 (8.1%) tests and revealed 144/2.189 (6.6%) patients with clinically relevant C. difficile infection.

Conclusions

Stool testing for enteric pathogens other than C. difficile should be avoided in ICU patients and is only reasonable when diarrhea commenced less than 48 h after hospital admission.