Clostridium difficile: a European perspective. J Infect. 2013;66:115-128. [PMID: 23103666 DOI: 10.1016/j.jinf.2012.10.019]

Exploring the intricacies of antimicrobial resistance: Understanding mechanisms, overcoming challenges, and pioneering innovative solutions

Antimicrobial resistance (AMR) poses a growing global threat. This review examines AMR from diverse angles, tracing the story of antibiotic resistance from its origins to today's crisis. It explores the rise of AMR, from its historical roots to the urgent need to counter this escalating menace. The review explores antibiotic classes, mechanisms, resistance profiles, and genetics. It details bacterial resistance mechanisms with illustrative examples. Multidrug-resistant bacteria spotlight AMR's resilience. Modern AMR control offers hope through precision medicine, stewardship, combination therapy, surveillance, and international cooperation. Converging traditional and innovative treatments presents an exciting frontier as novel compounds seek to enhance antibiotic efficacy. This review calls for global unity and proactive engagement to address AMR collectively, emphasizing the quest for innovative solutions and responsible antibiotic use. It underscores the interconnectedness of science, responsibility, and action in combatting AMR. Humanity faces a choice between antibiotic efficacy and obsolescence. The call is clear: unite, innovate, and prevail against AMR.

How to develop a controlled human infection model for Clostridioides difficile

BACKGROUND

Clostridioides difficile (C. difficile) remains the leading cause of healthcare-associated diarrhoea, posing treatment challenges because of antibiotic resistance and high relapse rates. Faecal microbiota transplantation is a novel treatment strategy to prevent relapses of C. difficile infection (CDI), however, the exact components conferring colonization resistance are unknown, hampering its translation to a medicinal product. The development of novel products independent of antibiotics, which increase colonization resistance or induce protective immune mechanisms is urgently needed.

OBJECTIVES

To establish a framework for a Controlled Human Infection Model (CHIM) of C. difficile, in which healthy volunteers are exposed to toxigenic C. difficile spores, offering the possibility to test novel approaches and identify microbiota and immunological targets. Whereas experimental exposure to non-toxigenic C. difficile has been done before, a toxigenic C. difficile CHIM faces ethical, scientific, logistical, and biosafety challenges.

SOURCES

Specific challenges in developing a C. difficile CHIM were discussed by a group of international experts during a workshop organized by Inno4Vac, an Innovative Health Initiative-funded consortium.

CONTENT

The experts agreed that the main challenges are: developing a clinically relevant CHIM that induces mild to moderate CDI symptoms but not severe CDI, determining the optimal C. difficile inoculum dose, and understanding the timing and duration of antibiotic pretreatment in inducing susceptibility to CDI in healthy volunteers.

IMPLICATIONS

Should these challenges be tackled, a C. difficile CHIM will not only provide a way forward for the testing of novel products but also offer a framework for a better understanding of the pathophysiology, pathogenesis, and immunology of C. difficile colonization and infection.

Abundant geographical divergence of Clostridioides difficile infection in China: a prospective multicenter cross-sectional study

Clostridioides difficile is the predominant pathogen in hospital-acquired infections and antibiotic-associated diarrhea. Dedicated networks and annual reports for C. difficile surveillance have been established in Europe and North America, however the extensive investigation on the prevalence of C. difficile infection (CDI) in China is limited. In this study, 1528 patients with diarrhea were recruited from seven geographically representative regions of China between July 2021 and July 2022. The positivity rate of toxigenic C. difficile using real-time fluorescence quantitative PCR test of feces was 10.2% (156/1528), and 125 (8.2%, 125/1528) strains were successfully isolated. The isolates from different geographical areas had divergent characteristics after multilocus sequence typing, toxin gene profiling, and antimicrobial susceptibility testing. No isolate from clade 2 were found, and clade 1 was still the main clade for these clinical isolates. Interestingly, clade 4, especially ST37, previously known as the characteristic type of China, showed a strong geographical divergence. Clade 3, although rare in China, has been detected in Hainan and Sichuan provinces. Most C. difficile isolates (76.8%, 96/125) were toxigenic. Clindamycin, erythromycin, and moxifloxacin were the top three antibiotics to which resistance was observed, with resistance rates of 81.3%, 63.6%, and 24.0%, respectively. Furthermore, 34 (27.2%, 34/125) multidrug-resistant (MDR) strains were identified. All the strains were sensitive to metronidazole, vancomycin, and meropenem. The genotype of C. difficile varies greatly among the different geographical regions in China, and new types are constantly emerging. Therefore, comprehensive, longitudinal, and standardized surveillance of C. difficile infections is needed in China, covering typical geographical areas.

Comparison of Illumina and Oxford Nanopore sequencing data quality for Clostridioides difficile genome analysis and their application for epidemiological surveillance

BACKGROUND

The burden of Clostridioides difficile as a nosocomial- and community-acquired pathogen has been increasing over the recent decades, including reports of severe outbreaks. Molecular and virulence genotyping are central for the epidemiological surveillance of this pathogen, but need to balance accuracy and rapid turnaround time of the results. While Illumina short-read sequencing has been adopted as the gold standard to investigate C. difficile virulence and transmission routes, little is known about the potential of Nanopore long-read sequencing in this field. The goal of our study was to compare sequencing and assembly quality of 37 C. difficile isolates using Illumina (SPAdes assembled) and Nanopore (Flye and Unicycler assembled) data alone, along with hybrid assemblies obtained with short-read polishing of long reads.

RESULTS

Illumina sequencing produced reads with an average quality of 99.68% (Q25), while Nanopore sequencing produced reads reaching an average quality of 96.84% (Q15), showing a tenfold difference in quality. Sequence type (ST) designation from Nanopore assemblies failed to detect ST5, ST7, ST8, ST13 and ST49, while ST designation based on unpolished Nanopore reads using Krocus was successful for all STs. Nanopore sequences exhibited an average of 640 base errors per genome (~ 0.015% substitution rate), which was reflected by the incorrect assignment of over 180 alleles in core genome multilocus sequence typing (cgMLST) analysis. As a result, Nanopore-derived phylogenies were not as accurate as the Illumina reference, and therefore inadequate for precise investigation of transmission events. Both sequencing platforms provided comparable, satisfactory results for the detection of virulence genes tcdA, tcdB, cdtAB and in-frame deletions in tcdC.

CONCLUSION

Compared to Illumina, Nanopore has higher error rate, which limits its application for high-resolution epidemiological surveillance. However, the short analysis time, lower cost and more simple procedure combined with correctly identified STs and virulence genes, makes it an alternative when fast and less detailed analyses are preferred.

Post-infectious ibs following Clostridioides difficile infection; role of microbiota and implications for treatment

Up to 25% of patients recovering from antibiotic-treated Clostridioides difficile infection (CDI) develop functional symptoms reminiscent of Post-Infectious Irritable Bowel Syndrome (PI-IBS). For patients with persistent symptoms following infection, a clinical dilemma arises as to whether to provide additional antibiotic treatment or to adopt a conservative symptom-based approach. Here, we review the literature on CDI-related PI-IBS and compare the findings with PI-IBS. We review proposed mechanisms, including the role of C. difficile toxins and the microbiota, and discuss implications for therapy. We suggest that gut dysfunction post-CDI may be initiated by toxin-induced damage to enteroglial cells and that a dysbiotic gut microbitota maintains the clinical phenotype over time, prompting consideration of microbiota-directed therapies. While Fecal Microbial Transplant (FMT) is currently reserved for recurrent CDI (rCDI), we propose that microbiota-directed therapies may have a role in primary CDI in order to avoid or mitigate futher antibiotic treatment that further disrupts the microbiota and thus prevent PI-IBS. We discuss novel microbial transfer therapies and as they emerge, we recommend clinical trials to determine whether microbial transfer therapy of the primary infection prevents both rCDI and CDI-related PI- IBS.

Deep learning-based prediction of Clostridioides difficile infection caused by antibiotics using longitudinal electronic health records

Clostridioides difficile infection (CDI) is a major cause of antibiotic-associated diarrhea and colitis. It is recognized as one of the most significant hospital-acquired infections. Although CDI can develop severe complications and spores of Clostridioides difficile can be transmitted by the fecal-oral route, CDI is occasionally overlooked in clinical settings. Thus, it is necessary to monitor high CDI risk groups, particularly those undergoing antibiotic treatment, to prevent complications and spread. We developed and validated a deep learning-based model to predict the occurrence of CDI within 28 days after starting antibiotic treatment using longitudinal electronic health records. For each patient, timelines of vital signs and laboratory tests with a 35-day monitoring period and a patient information vector consisting of age, sex, comorbidities, and medications were constructed. Our model achieved the prediction performance with an area under the receiver operating characteristic curve of 0.952 (95% CI: 0.932-0.973) in internal validation and 0.972 (95% CI: 0.968-0.975) in external validation. Platelet count and body temperature emerged as the most important features. The risk score, the output value of the model, exhibited a consistent increase in the CDI group, while the risk score in the non-CDI group either maintained its initial value or decreased. Using our CDI prediction model, high-risk patients requiring symptom monitoring can be identified. This could help reduce the underdiagnosis of CDI, thereby decreasing transmission and preventing complications.

Estimating excess mortality and economic burden of Clostridioides difficile infections and recurrences during 2015-2019: the RECUR Germany study

BACKGROUND

Clostridioides difficile infections (CDIs) and recurrences (rCDIs) remain a major public health challenge due to substantial mortality and associated costs. This study aims to generate real-world evidence on the mortality and economic burden of CDI in Germany using claims data between 2015 and 2019.

METHODS

A longitudinal and matched cohort study using retrospective data from Statutory Health Insurance (SHI) was conducted in Germany with the BKK database. Adults diagnosed with CDI in hospital and community settings between 2015 and 2018 were included in the study. Patients had a minimum follow-up of 12-months. All-cause mortality was described at 6-, 12-, and 24-months. Healthcare resource usage (HCRU) and associated costs were assessed at 12-months of follow-up. A cohort of non-CDI patients matched by demographic and clinical characteristics was used to assess excess mortality and incremental costs of HCRU. Up to three non-CDI patients were matched to each CDI patient.

RESULTS

A total of 9,977 CDI patients were included in the longitudinal cohort. All-cause mortality was 32%, 39% and 48% at 6-, 12-, and 24-months, respectively, with minor variations by number of rCDIs. When comparing matched CDI (n = 5,618) and non-CDI patients (n = 16,845), CDI patients had an excess mortality of 2.17, 1.35, and 0.94 deaths per 100 patient-months, respectively. HCRU and associated costs were consistently higher in CDI patients compared to non-CDI patients and increased with recurrences. Total mean and median HCRU cost per patient during follow-up was €12,893.56 and €6,050 in CDI patients, respectively, with hospitalisations representing the highest proportion of costs. A total mean incremental cost per patient of €4,101 was estimated in CDI patients compared to non-CDI patients, increasing to €13,291 in patients with ≥ 3 rCDIs.

CONCLUSIONS

In this real-world study conducted in Germany, CDI was associated with increased risk of death and substantial costs to health systems due to higher HCRU, especially hospitalisations. HCRU and associated costs were exacerbated by rCDIs.

A commensal protozoan attenuates Clostridioides difficile pathogenesis in mice via arginine-ornithine metabolism and host intestinal immune response

Antibiotic-induced dysbiosis is a major risk factor for Clostridioides difficile infection (CDI), and fecal microbiota transplantation (FMT) is recommended for treating CDI. However, the underlying mechanisms remain unclear. Here, we show that Tritrichomonas musculis (T.mu), an integral member of the mouse gut commensal microbiota, reduces CDI-induced intestinal damage by inhibiting neutrophil recruitment and IL-1β secretion, while promoting Th1 cell differentiation and IFN-γ secretion, which in turn enhances goblet cell production and mucin secretion to protect the intestinal mucosa. T.mu can actively metabolize arginine, not only influencing the host's arginine-ornithine metabolic pathway, but also shaping the metabolic environment for the microbial community in the host's intestinal lumen. This leads to a relatively low ornithine state in the intestinal lumen in C. difficile-infected mice. These changes modulate C. difficile's virulence and the host intestinal immune response, and thus collectively alleviating CDI. These findings strongly suggest interactions between an intestinal commensal eukaryote, a pathogenic bacterium, and the host immune system via inter-related arginine-ornithine metabolism in the regulation of pathogenesis and provide further insights for treating CDI.

A Streamlined Method to Obtain Biologically Active TcdA and TcdB Toxins from Clostridioides difficile

The major virulence factors of Clostridioides difficile (C. difficile) are enterotoxins A (TcdA) and B (TcdB). The study of toxins is a crucial step in exploring the virulence of this pathogen. Currently, the toxin purification process is either laborious and time-consuming in C. difficile or performed in heterologous hosts. Therefore, we propose a streamlined method to obtain functional toxins in C. difficile. Two C. difficile strains were generated, each harboring a sequence encoding a His-tag at the 3' end of C. difficile 630∆erm tcdA or tcdB genes. Each toxin gene is expressed using the Ptet promoter, which is inducible by anhydro-tetracycline. The obtained purification yields were 0.28 mg and 0.1 mg per liter for rTcdA and rTcdB, respectively. In this study, we successfully developed a simple routine method that allows the production and purification of biologically active rTcdA and rTcdB toxins with similar activities compared to native toxins.

Economic Burden of Clostridioides difficile Infection in European Countries

Clostridioides difficile infection (CDI) remains a considerable challenge to healthcare systems worldwide. Although CDI represents a significant burden on healthcare systems in Europe, few studies have attempted to estimate the consumption of resources associated with CDI in Europe. The reported extra costs attributable to CDI vary widely according to the definitions, design, and methodologies used, making comparisons difficult to perform. In this chapter, the economic burden of healthcare facility-associated CDI in Europe will be assessed, as will other less explored areas such as the economic burden of recurrent CDI, community-acquired CDI, pediatric CDI, and CDI in outbreaks.

Clostridioides difficile infections; new treatments and future perspectives

PURPOSE OF REVIEW

As a significant cause of global morbidity and mortality, Clostridioides difficile infections (CDIs) are listed by the Centres for Disease Control and prevention as one of the top 5 urgent threats in the USA. CDI occurs from gut microbiome dysbiosis, typically through antibiotic-mediated disruption; however, antibiotics are the treatment of choice, which can result in recurrent infections. Here, we highlight new treatments available and provide a perspective on different classes of future treatments.

RECENT FINDINGS

Due to the reduced risk of disease recurrence, the microbiome-sparing antibiotic Fidaxomicin has been recommended as the first-line treatment for C. difficile infection. Based on the success of faecal microbiota transplantations (FMT) in treating CDI recurrence, defined microbiome biotherapeutics offer a safer and more tightly controlled alterative as an adjunct to antibiotic therapy. Given the association between antibiotic-mediated dysbiosis of the intestinal microbiota and the recurrence of CDI, future prospective therapies aim to reduce the dependence on antibiotics for the treatment of CDI.

SUMMARY

With current first-in-line antibiotic therapy options associated with high levels of recurrent CDI, the availability of new generation targeted therapeutics can really impact treatment success. There are still unknowns about the long-term implications of these new CDI therapeutics, but efforts to expand the CDI treatment toolbox can offer multiple solutions for clinicians to treat this multifaceted infectious disease to reduce patient suffering.

A Pharmacovigilance Study Regarding the Risk of Antibiotic-Associated Clostridioides difficile Infection Based on Reports from the EudraVigilance Database: Analysis of Some of the Most Used Antibiotics in Intensive Care Units

The Gram-positive anaerobic bacterium Clostridioides difficile (CD) can produce intense exotoxins, contributing to nosocomial infections, and it is the most common cause of health-care-associated infectious diarrhea. Based on spontaneous Individual Case Safety Reports from EudraVigilance (EV), we conducted a descriptive analysis of Clostridioides difficile infection (CDI) cases that reported a spontaneous adverse reaction related to using ceftriaxone, colistimethate, ciprofloxacin, gentamicin, linezolid, meropenem, and piperacillin/tazobactam. Most ADR reports registered in EV that were related to CDI were associated with ceftriaxone (33%), ciprofloxacin (28%), and piperacillin/tazobactam (21%). Additionally, the disproportionality analysis performed showed that all studied antibiotics had a lower reporting probability when compared to clindamycin. A causal relationship between a drug and the occurrence of an adverse reaction cannot be established from EV data alone because the phenomena of underreporting, overreporting, and reporting bias may affect the results. Based on the analysis of the collected data, this study underlines the importance of surveillance and monitoring programs for the consumption of antibiotics. Furthermore, it is essential to use standardized laboratory tests to define CDI's nature accurately. To prevent this infection, specialists should collaborate and adhere strictly to antibiotic stewardship programs, hygiene practices, and isolation protocols.

A sporulation signature protease is required for assembly of the spore surface layers, germination and host colonization in Clostridioides difficile

A genomic signature for endosporulation includes a gene coding for a protease, YabG, which in the model organism Bacillus subtilis is involved in assembly of the spore coat. We show that in the human pathogen Clostridioidesm difficile, YabG is critical for the assembly of the coat and exosporium layers of spores. YabG is produced during sporulation under the control of the mother cell-specific regulators σE and σK and associates with the spore surface layers. YabG shows an N-terminal SH3-like domain and a C-terminal domain that resembles single domain response regulators, such as CheY, yet is atypical in that the conserved phosphoryl-acceptor residue is absent. Instead, the CheY-like domain carries residues required for activity, including Cys207 and His161, the homologues of which form a catalytic diad in the B. subtilis protein, and also Asp162. The substitution of any of these residues by Ala, eliminates an auto-proteolytic activity as well as interdomain processing of CspBA, a reaction that releases the CspB protease, required for proper spore germination. An in-frame deletion of yabG or an allele coding for an inactive protein, yabGC207A, both cause misassemby of the coat and exosporium and the formation of spores that are more permeable to lysozyme and impaired in germination and host colonization. Furthermore, we show that YabG is required for the expression of at least two σK-dependent genes, cotA, coding for a coat protein, and cdeM, coding for a key determinant of exosporium assembly. Thus, YabG also impinges upon the genetic program of the mother cell possibly by eliminating a transcriptional repressor. Although this activity has not been described for the B. subtilis protein and most of the YabG substrates vary among sporeformers, the general role of the protease in the assembly of the spore surface is likely to be conserved across evolutionary distance.

Potential causal effect of contact precautions and isolation on Clostridioides difficile infection in the hyperendemic setting: Interrupted time-series analyses before and after implementation

BACKGROUND

Recent studies disputed the effectiveness of efforts to comply with contact precautions and isolation (CPI) considering relatively low intra-hospital transmission rate of healthcare facility-associated Clostridioides difficile infection (HCFA-CDI). We evaluated the potential causal effect of CPI on HCFA-CDI occurrence by comparing the incidence rate (IR) for different time periods with and without CPI implementation.

METHODS

Long-term observational time-series data were separated into three periods (pre-CPI: January 2012-March 2016, CPI: April 2016-April 2021, post-CPI: May 2021-December 2022). CPI was suspended owing to the restriction of isolation rooms during the COVID-19 pandemic. We inferred potential causal outcomes by comparing predicted and observed IRs of HCFA-CDI using interrupted time-series analyses, including the Bayesian structural time-series or autoregressive integrated moving average (ARIMA) model in the R-language or SAS software.

RESULTS

The monthly observed IR (44.9/100,000 inpatient-days) during the CPI period was significantly lower than the predicted IR (90.8) (-50.6% relative effect, P = 0.001). However, the observed IR (52.3) during the post-CPI period was significantly higher than the predicted IR (39.1) (33.6%, P = 0.001). The HCFA-CDI IR decreased during CPI (-14.3, P < 0.001) and increased post-CPI (5.4, P < 0.001) in the multivariable ARIMA model, which controlled for antibiotic usage, handwashing with soap and water, and number of toxin tests.

CONCLUSIONS

Various time-series models revealed that CPI implementation had a potential causal effect on the reduction of HCFA-CDI incidence.

The Environment, Farm Animals and Foods as Sources of Clostridioides difficile Infection in Humans

The recent discovery of the same Clostridioides difficile ribotypes associated with human infection in a broad range of environments, animals and foods, coupled with an ever-increasing rate of community-acquired infections, suggests this pathogen may be foodborne. The objective of this review was to examine the evidence supporting this hypothesis. A review of the literature found that forty-three different ribotypes, including six hypervirulent strains, have been detected in meat and vegetable food products, all of which carry the genes encoding pathogenesis. Of these, nine ribotypes (002, 003, 012, 014, 027, 029, 070, 078 and 126) have been isolated from patients with confirmed community-associated C. difficile infection (CDI). A meta-analysis of this data suggested there is a higher risk of exposure to all ribotypes when consuming shellfish or pork, with the latter being the main foodborne route for ribotypes 027 and 078, the hypervirulent strains that cause most human illnesses. Managing the risk of foodborne CDI is difficult as there are multiple routes of transmission from the farming and processing environment to humans. Moreover, the endospores are resistant to most physical and chemical treatments. The most effective current strategy is, therefore, to limit the use of broad-spectrum antibiotics while advising potentially vulnerable patients to avoid high-risk foods such as shellfish and pork.

Detection and Genomic Characterisation of Clostridioides difficile from Spinach Fields

Despite an increased incidence of Clostridioides difficile infections, data on the reservoirs and dissemination routes of this bacterium are limited. This study examined the prevalence and characteristics of C. difficile isolates in spinach fields. C. difficile was detected in 2/60 (3.3%) of spinach and 6/60 (10%) of soil samples using culture-based techniques. Whole genome sequencing (WGS) analysis identified the spinach isolates as belonging to the hypervirulent clade 5, sequence type (ST) 11, ribotypes (RT) 078 and 126 and carried the genes encoding toxins A, B and CDT. The soil isolates belonged to clade 1 with different toxigenic ST/RT (ST19/RT614, ST12/RT003, ST46/RT087, ST16/RT050, ST49/RT014/0) strains and one non-toxigenic ST79/RT511 strain. Antimicrobial resistance to erythromycin (one spinach isolate), rifampicin (two soil isolates), clindamycin (one soil isolate), both moxifloxacin and rifampicin (one soil isolate), and multi-drug resistance to erythromycin, vancomycin and rifampicin (two soil isolates) were observed using the E test, although a broader range of resistance genes were detected using WGS. Although the sample size was limited, our results demonstrate the presence of C. difficile in horticulture and provide further evidence that there are multiple sources and dissemination routes for these bacteria.

An Update on Clostridioides difficile Binary Toxin

Infection with Clostridioides difficile (CDI), a common healthcare-associated infection, includes symptoms ranging from mild diarrhea to severe cases of pseudomembranous colitis. Toxin A (TcdA) and toxin B (TcdB) cause cytotoxicity and cellular detachment from intestinal epithelium and are responsible for CDI symptomatology. Approximately 20% of C. difficile strains produce a binary toxin (CDT) encoded by the tcdA and tcdB genes, which is thought to enhance TcdA and TcdB toxicity; however, the role of CDT in CDI remains controversial. Here, we focused on describing the main features of CDT and its impact on the host, clinical relevance, epidemiology, and potential therapeutic approaches.

A lipoprotein allosterically activates the CwlD amidase during Clostridioides difficile spore formation

Spore-forming pathogens like Clostridioides difficile depend on germination to initiate infection. During gemination, spores must degrade their cortex layer, which is a thick, protective layer of modified peptidoglycan. Cortex degradation depends on the presence of the spore-specific peptidoglycan modification, muramic-∂-lactam (MAL), which is specifically recognized by cortex lytic enzymes. In C. difficile, MAL production depends on the CwlD amidase and its binding partner, the GerS lipoprotein. To gain insight into how GerS regulates CwlD activity, we solved the crystal structure of the CwlD:GerS complex. In this structure, a GerS homodimer is bound to two CwlD monomers such that the CwlD active sites are exposed. Although CwlD structurally resembles amidase_3 family members, we found that CwlD does not bind Zn²⁺ stably on its own, unlike previously characterized amidase_3 enzymes. Instead, GerS binding to CwlD promotes CwlD binding to Zn²⁺, which is required for its catalytic mechanism. Thus, in determining the first structure of an amidase bound to its regulator, we reveal stabilization of Zn²⁺ co-factor binding as a novel mechanism for regulating bacterial amidase activity. Our results further suggest that allosteric regulation by binding partners may be a more widespread mode for regulating bacterial amidase activity than previously thought.

Spore germination is essential for many spore-forming pathogens to initiate infection. In order for spores to germinate, they must degrade a thick, protective layer of cell wall known as the cortex. The enzymes that digest this layer selectively recognize the spore-specific cell wall modification, muramic-∂-lactam (MAL). MAL is made in part through the activity of the CwlD amidase, which is found in all spore-forming bacteria. While Bacillus subtilis CwlD appears to have amidase activity on its own, Clostridioides difficile CwlD activity depends on its binding partner, the GerS lipoprotein. To understand why C. difficile CwlD requires GerS, we determined the X-ray crystal structure of the CwlD:GerS complex and discovered that GerS binds to a site distant from CwlD’s active site. We also found that GerS stabilizes CwlD binding to its co-factor, Zn²⁺, indicating that GerS allosterically activates CwlD amidase. Notably, regulation at the level of Zn²⁺ binding has not previously been described for bacterial amidases, and GerS is the first protein to be shown to allosterically activate an amidase. Since binding partners of bacterial amidases were only first discovered 15 years ago, our results suggest that diverse mechanisms remain to be discovered for these critical enzymes.

A cost of illness comparison for toxigenic Clostridioides difficile diagnosis algorithms in developing countries

BACKGROUND

Availability of several commercial tests with different Clostridioides difficile targets contributes to uncertainty and controversies around the optimal diagnostic algorithm. While numerous studies have estimated the financial impact of C. difficile infection, models to guide testing strategies decisions in developing countries, where economic value significantly impacts clinical practice, are currently not available.

AIM

To determine the cost of illness of different C. difficile infection (CDI) diagnostic strategies in developing countries.

METHODS

Cost-comparison analysis was performed to compare eleven different algorithms of CDI diagnosis. The basis of calculation was a hypothetical cohort of 1000 adult inpatients suspected of CDI. We analyzed turnaround time of test results (i.e., time from taking sample to results emission), test performance (i.e., sensitivity and specificity) and testing costs. Patients were divided in true positive, false positive, true negative and false negative in order to integrate test performance and economics effects. Additional medical costs were calculated: costs of hygiene, medication, length of stay and intensive care unit costs, based on a Brazilian University Hospital costs. CDI prevalence was considered 22.64%.

FINDINGS

From laboratory-assisted tests, simultaneous glutamate dehydrogenase (GDH) and toxin A/B rapid immunoassay arbitrated by nucleic acid amplification test (NAAT) presented the lowest cost of illness (450,038.70 USD), whereas standalone NAAT had the highest (523,709.55 USD). Empirical diagnosis only presented the highest overall cost (809,605.44 USD).

CONCLUSION

The two-step algorithm with simultaneous GDH and toxin A/B rapid immunoassay arbitrated by NAAT seems to be the best strategy for CDI diagnosis in developing countries.

Clostridioides difficile Spore Formation and Germination: New Insights and Opportunities for Intervention

Spore formation and germination are essential for the bacterial pathogen Clostridioides difficile to transmit infection. Despite the importance of these developmental processes to the infection cycle of C. difficile, the molecular mechanisms underlying how this obligate anaerobe forms infectious spores and how these spores germinate to initiate infection were largely unknown until recently. Work in the last decade has revealed that C. difficile uses a distinct mechanism for sensing and transducing germinant signals relative to previously characterized spore formers. The C. difficile spore assembly pathway also exhibits notable differences relative to Bacillus spp., where spore formation has been more extensively studied. For both these processes, factors that are conserved only in C. difficile or the related Peptostreptococcaceae family are employed, and even highly conserved spore proteins can have differential functions or requirements in C. difficile compared to other spore formers. This review summarizes our current understanding of the mechanisms controlling C. difficile spore formation and germination and describes strategies for inhibiting these processes to prevent C. difficile infection and disease recurrence.

Burden of Clostridioides difficile infection (CDI) - a systematic review of the epidemiology of primary and recurrent CDI

BACKGROUND

Clostridioides difficile is a Gram-positive anaerobic bacterium, which causes Clostridioides difficile infection (CDI). It has been recognised as a leading cause of healthcare-associated infections and a considerable threat to public health globally. This systematic literature review (SLR) summarises the current evidence on the epidemiology and clinical burden of CDI.

METHODS

A SLR was conducted to identify CDI and recurrent CDI (rCDI) epidemiology studies, to evaluate patient and disease characteristics, incidence rates, epidemiological findings and risk factors. Embase, MEDLINE and the Cochrane Library databases were searched for English articles from 2009 to 2019. Included territories were the United Kingdom, France, Germany, Italy, Spain, Poland, US, Canada, Australia, Japan and China.

RESULTS

Of 11,243 studies identified, 165 fulfilled the selection criteria. An additional 20 studies were identified through targeted review of grey literature. The most widely reported findings were incidence and risk factors for CDI and rCDI. Among key studies reporting both healthcare-associated (HA-CDI) and community-associated CDI (CA-CDI) incidence rates for each country of interest, incidence rates per 10,000 patient days in the US were 8.00 and 2.00 for HA-CDI and CA-CDI, respectively. The highest incidence in Europe was reported in Poland (HA-CDI: 6.18 per 10,000 patient days, CA-CDI: 1.4 per 10,000 patient days), the lowest from the UK, at 1.99 per 10,000 patient days and 0.56 per 10,000 patient days for HA-CDI and CA-CDI, respectively. No clear trend for incidence over time emerged, with most countries reporting stable rates but some either a decrease or increase. Rates of recurrent CDI varied based on geographical setting. The rate of recurrence was lower in community-associated disease compared to healthcare-associated disease. Independent CDI risk factors identified common to both initial CDI and recurrent CDI included increasing age, antibiotic use, recent hospitalisation, and proton pump inhibitor (PPI) use. In addition, leukocyte count, length of hospital stays, and Charlson comorbidity index score featured as statistically significant risk factors for recurrent CDI, but these are not reported among the most common statistically significant risk factors for initial CDI.

CONCLUSIONS

Despite considerable heterogeneity, evidence suggests substantial incidence of recurrent and primary CDI, even after considerable efforts in the last decade.

An inexpensive anaerobic chamber for the genetic manipulation of strictly anaerobic bacteria

Strictly anaerobic bacteria are important to both human health and industrial usage. These bacteria are sensitive to oxygen, therefore, it is preferable to manipulate these microbes in an anaerobic chamber. However, commercial anaerobic chambers (CACs) are expensive, making them less accessible to scientists with a limited budget, especially to those in developing countries. The high price of commercial chambers has hindered, at least partially, the progress of research on anaerobes in developing countries. In the research presented here, we developed an inexpensive and reliable anaerobic chamber and successfully achieved routine maintenance of eleven strictly anaerobic bacterial strains. Furthermore, genetic manipulation examples have been set for both Clostridioidesdifficile 630 and Clostridiumbeijerinckii NCIMB 8052 strains to validate that the chamber could applied to advanced genetic engineering of strictly anaerobes. C. difficile and C. beijerinckii were both genetically manipulated in this chamber, showing it's utility for the genetic engineering of anaerobes. Most importantly, the anaerobic chamber was 76% - 88% less expensive than a CACs and has similar functionality with regards to the cultivation and manipulation of strictly anaerobic bacteria. The anaerobic chamber described in this study will promote the research of anaerobes in developing counties and scientists who have limited research budgets.

Clostridioides difficile in Calves in Central Italy: Prevalence, Molecular Typing, Antimicrobial Susceptibility and Association with Antibiotic Administration

Simple Summary

Clostridioides difficile is a leading cause of nosocomial and community-acquired diarrhoea in men. The infection most commonly occurs in people who have recently been treated with antibiotics. Indistinguishable C. difficile strains have been isolated from livestock and humans, which has shed light on a possible zoonotic origin of this infection. This study aimed to assess the prevalence and risk factors of C. difficile in calves bred in dairy and beef cattle farms of the Umbria, central Italy. We estimated a 19.8% prevalence of farms positive for C. difficile. The C. difficile isolates from calves were potentially toxigenic and resistant to antibiotics, including lincosamides, quinolones, vancomycin and linezolid. Isolates belonging to ribotype RT-126, which is also commonly reported in humans, showed the highest number of resistance to the antimicrobials tested. Furthermore, we observed an almost sixfold increased risk for C. difficile on farms where penicillins had been prescribed. This, together with the detection of toxigenic and antibiotic-resistant isolates, strongly suggests the need for a reduction of antibiotic use in cattle.

Abstract

The emergence of Clostridioides difficile as the main agent of antibiotic-associated diarrhoea has raised concerns about its potential zoonotic role in different animal species. The use of antimicrobials is a major risk factor for C. difficile infection. Here, we provide data on C. difficile infection in dairy and beef calves in Umbria, a region in central Italy. This cross-sectional study focuses on prevalence, risk factors, ribotypes, toxinotypes and antimicrobial resistance profiles of circulating ribotypes. A prevalence of 19.8% (CI95%, 12–27.6%) positive farms was estimated, and the prescription of penicillins on the farms was associated with C. difficile detection (OR = 5.58). Eleven different ribotypes were found, including the ST11 sublineages RT-126 and -078, which are also commonly reported in humans. Thirteen isolates out of 17 showed resistance to at least one of clindamycin, moxifloxacin, linezolid and vancomycin. Among them, multiple-drug resistance was observed in two isolates, belonging to RT-126. Furthermore, RT-126 isolates were positive for tetracycline resistance determinants, confirming that tetracycline resistance is widespread among ST11 isolates from cattle. The administration of penicillins increased the risk of C. difficile in calves: this, together with the recovery of multi-resistant strains, strongly suggests the need for minimising antibiotic misuse on cattle farms.

A multicentre analysis of Clostridium difficile in persons with Cystic Fibrosis demonstrates that carriage may be transient and highly variable with respect to strain and level

PURPOSE

Clostridium difficile has been reported to occur in the gastrointestinal tract of 50% of Cystic Fibrosis (CF) subjects, however, clinical C. difficile infection (CDI) is a rare occurrence in this cohort despite the presence of toxigenic and hypervirulent ribotypes. Here, we present the first longitudinal, multicentre analysis of C. difficile prevalence among adult CF subjects.

METHODOLOGY

Faecal samples were collected from adults with CF (selected based on confirmed Pseudomonas aeruginosa pulmonary colonisation) from Ireland, UK and Belgium as part of the CFMATTERS clinical research trial (grant No. 603038) and from non-CF controls. Faecal samples were collected on enrolment, at three monthly intervals, during pulmonary exacerbation and three months post exacerbation. C. difficile was isolated from faecal samples by ethanol shocking followed by culturing on cycloserine cefoxitin egg yolk agar. Isolates were characterised in terms of ribotype, toxin type and antibiotic susceptibility to antibiotics routinely used in the treatment of CDI (metronidazole and vancomycin) and those implicated in induction of CDI (ciprofloxacin and moxifloxacin).

RESULTS

Prevalence of C. difficile among CF subjects in the three sites was similar ranging from 47% to 50% at baseline, while the healthy control cohort had a carriage rate of 7.1%. Including subjects who were positive for C. difficile at any time point there was a higher carriage rate of 71.4%, 66.7% and 63.2% in Ireland, UK, and Belgium, respectively. Ribotyping of 80 isolates from 45 CF persons, over multiple time points revealed 23 distinct ribotypes with two ribotypes (046 and 078) shared by all centres. The proportion of toxigenic isolates varied across the sites, ranging from 66.7% in Ireland to 52.9% in Belgium and 100% in the UK. Antibiotic susceptibility rates to vancomycin, metronidazole, ciprofloxacin and moxifloxacin was 100%, 97.5%, 1.3% and 63.8%, respectively.

CONCLUSIONS

This study demonstrates the highest carriage rate of C. difficile to date in a CF cohort. Longitudinal data show that C. difficile can be a transient inhabitant of the CF gut, changing both in terms of strain and excretion rates.

New generation biologics for the treatment of psoriasis and psoriatic arthritis. State of the art and considerations about the risk of infection

Psoriasis is a chronic immune-mediated disease characterized by inflammation of skin (psoriasis) or joints (psoriatic arthritis) or both, resulting from a dysregulation in particular of the T helper (Th)17 functions. There is no available cure for psoriasis, and a life-long treatment is needed to control signs and symptoms. Research interest is high around the newest biological drugs approved for the treatment of moderate to severe psoriasis and psoriatic arthritis, and especially drugs blocking the IL-23/IL-17 axis. Our aim is to review the new biological drugs for the treatment of psoriasis and their adverse effects, focusing on the risk of infections.

Peptidoglycan analysis reveals that synergistic deacetylase activity in vegetative Clostridium difficile impacts the host response

Clostridium difficile is an anaerobic and spore-forming bacterium responsible for 15-25% of postantibiotic diarrhea and 95% of pseudomembranous colitis. Peptidoglycan is a crucial element of the bacterial cell wall that is exposed to the host, making it an important target for the innate immune system. The C. difficile peptidoglycan is largely N-deacetylated on its glucosamine (93% of muropeptides) through the activity of enzymes known as N-deacetylases, and this N-deacetylation modulates host-pathogen interactions, such as resistance to the bacteriolytic activity of lysozyme, virulence, and host innate immune responses. C. difficile genome analysis showed that 12 genes potentially encode N-deacetylases; however, which of these N-deacetylases are involved in peptidoglycan N-deacetylation remains unknown. Here, we report the enzymes responsible for peptidoglycan N-deacetylation and their respective regulation. Through peptidoglycan analysis of several mutants, we found that the N-deacetylases PdaV and PgdA act in synergy. Together they are responsible for the high level of peptidoglycan N-deacetylation in C. difficile and the consequent resistance to lysozyme. We also characterized a third enzyme, PgdB, as a glucosamine N-deacetylase. However, its impact on N-deacetylation and lysozyme resistance is limited, and its physiological role remains to be dissected. Finally, given the influence of peptidoglycan N-deacetylation on host defense against pathogens, we investigated the virulence and colonization ability of the mutants. Unlike what has been shown in other pathogenic bacteria, a lack of N-deacetylation in C. difficile is not linked to a decrease in virulence.

STRUCTURING A FECAL MICROBIOTA TRANSPLANTATION CENTER IN A UNIVERSITY HOSPITAL IN BRAZIL

BACKGROUND

Fecal microbiota transplantation (FMT) is an important therapeutic option for recurrent or refractory Clostridioides difficile infection, being a safe and effective method. Initial results suggest that FMT also plays an important role in other conditions whose pathogenesis involves alteration of the intestinal microbiota. However, its systematized use is not widespread, especially in Brazil. In the last decade, multiple reports and several cases emerged using different protocols for FMT, without standardization of methods and with variable response rates. In Brazil, few isolated cases of FMT have been reported without the implantation of a Fecal Microbiota Transplantation Center (FMTC).

OBJECTIVE

The main objective of this study is to describe the process of implanting a FMTC with a stool bank, in a Brazilian university hospital for treatment of recurrent and refractory C. difficile infection.

METHODS

The center was structured within the criteria required by international organizations such as the Food and Drug Administration, the European Fecal Microbiota Transplant Group and in line with national epidemiological and regulatory aspects.

RESULTS

A whole platform involved in structuring a transplant center with stool bank was established. The criteria for donor selection, processing and storage of samples, handling of recipients before and after the procedure, routes of administration, short and long-term follow-up of transplant patients were determined. Donor selection was conducted in three stages: pre-screening, clinical evaluation and laboratory screening. Most of the candidates were excluded in the first (75.4%) and second stage (72.7%). The main clinical exclusion criteria were: recent acute diarrhea, overweight (body mass index ≥25 kg/m2) and chronic gastrointestinal disorders. Four of the 134 candidates were selected after full screening, with a donor detection rate of 3%.

CONCLUSION

The implantation of a transplant center, unprecedented in our country, allows the access of patients with recurrent or refractory C. difficile infection to innovative, safe treatment, with a high success rate and little available in Brazil. Proper selection of qualified donors is vital in the process of implementing a FMTC. The rigorous clinical evaluation of donors allowed the rational use of resources. A transplant center enables treatment on demand, on a larger scale, less personalized, with more security and traceability. This protocol provides subsidies for conducting FMT in emerging countries.

A 2-step algorithm combining glutamate dehydrogenase and nucleic acid amplification tests for the detection of Clostridioides difficile in stool specimens

The optimized diagnosis algorithm of Clostridioides difficile infection (CDI) is worldwide concerns. The purpose of this study was to assess the toxigenic C. difficile test performance and propose an optimal laboratory workflow for the diagnosis of CDI in mild virulent epidemic areas. Diarrhea samples collected from patients were analyzed by glutamate dehydrogenase (GDH), toxin AB (CDAB), and nucleic acid amplification test (NAAT). We assessed the performance of GDH, the GDH-CDAB algorithm, and the GDH-NAAT algorithm using toxigenic culture (TC) as a reference method. In this study, 186 diarrhea samples were collected. The numbers of TC-positive and TC-negative samples were 39 and 147, respectively. The sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and kappa of the GDH assay were 100%, 80.3%, 57.4%, 100%, and 0.63; of the GDH-CDAB algorithm were 48.7%, 97.3%, 82.6%, 87.7%, and 0.54; and of the GDH-NAAT algorithm were 74.4%, 100%, 100%, 93.6%, and 0.82, respectively. The GDH-NAAT algorithm has great concordance with TC in detecting toxigenic C. difficile (kappa = 0.82), while the sensitivity of the GDH-CDAB algorithm was too low to meet the demand of CDI diagnosis clinically. GDH-NAAT algorithm is recommended for the detection of toxigenic C. difficile with high specificity, increased sensitivity, and cost-effective.

The (p)ppGpp Synthetase RSH Mediates Stationary-Phase Onset and Antibiotic Stress Survival in Clostridioides difficile

The human pathogen Clostridioides difficile is increasingly tolerant of multiple antibiotics and causes infections with a high rate of recurrence, creating an urgent need for new preventative and therapeutic strategies. The stringent response, a universal bacterial response to extracellular stress, governs antibiotic survival and pathogenesis in diverse organisms but has not previously been characterized in C. difficile Here, we report that the C. difficile (p)ppGpp synthetase RSH is incapable of utilizing GTP or GMP as a substrate but readily synthesizes ppGpp from GDP. The enzyme also utilizes many structurally diverse metal cofactors for reaction catalysis and remains functionally stable at a wide range of environmental pHs. Transcription of rsh is stimulated by stationary-phase onset and by exposure to the antibiotics clindamycin and metronidazole. Chemical inhibition of RSH by the ppGpp analog relacin increases antibiotic susceptibility in epidemic C. difficile R20291, indicating that RSH inhibitors may be a viable strategy for drug development against C. difficile infection. Finally, transcriptional suppression of rsh also increases bacterial antibiotic susceptibility, suggesting that RSH contributes to C. difficile antibiotic tolerance and survival.IMPORTANCE Clostridioides difficile infection (CDI) is an urgent public health threat with a high recurrence rate, in part because the causative bacterium has a high rate of antibiotic survival. The (p)ppGpp-mediated bacterial stringent response plays a role in antibiotic tolerance in diverse pathogens and is a potential target for development of new antimicrobials because the enzymes that metabolize (p)ppGpp have no mammalian homologs. We report that stationary-phase onset and antibiotics induce expression of the clostridial ppGpp synthetase RSH and that both chemical inhibition and translational suppression of RSH increase C. difficile antibiotic susceptibility. This demonstrates that development of RSH inhibitors to serve as adjuvants to antibiotic therapy is a potential approach for the development of new strategies to combat CDI.

Comparing the epidemiology of community- and hospital-associated Clostridium difficile infections in Northern Ireland, 2012-2016: a population data linkage and case-case study

The burden of community-associated Clostridium difficile infection (CA-CDI) has increased. We aimed to describe the epidemiology of CA-CDI to inform future interventions. We used population-based linked surveillance data from 2012 to 2016 to describe socio-demographic factors, ribotype and mortality for all CA (n = 1303) and hospital-associated (HA, n = 1356) CDI. For 483 community-onset (CO) CA-CDI and 287 COHA-CDI cases, a questionnaire on risk factors was completed and we conducted a case-case study using logistic regression models for univariate and multivariable analysis. CA-CDI cases had lower odds of being male (adjusted odds ratio (AOR) 0.71, 95% confidence interval (CI) 0.58-0.87; P &lt; 0.001), and higher odds of living in rural rather than urban settlement (AOR 1.5, 95% CI 1.1-2.1; P = 0.05) compared with HA-CDI cases. The distribution of ribotypes was similar in both groups with RT078 being most prevalent. CDI-specific death was lower in CA-CDI than HA-CDI (7% vs. 11%, P &lt; 0.001). COCA-CDI had lower odds of having had an outpatient appointment in the previous 4 weeks compared with COHA-CDI (AOR 0.61; 95% CI 0.41-0.9, P = 0.01) and lower odds of being in a care home or hospice when compared with their own home, than COHA-CDI (AOR 0.66; 95% CI 0.45-0.98 and AOR 0.35; 95% CI 0.13-0.92, P = 0.02). Exposure to gastric acid suppressants (50% in COCA-CDI and 55% in COHA-CDI) and antimicrobial therapy (18% in COCA-CDI and 20% in COHA-CDI) prior to CDI was similar. Our analysis of community-onset cases suggests that other risk factors for COHA-CDI may be equally important for COCA-CDI. Opportunities to safely reduce antibiotic and gastric acid suppressants use should be investigated in all healthcare settings.

Molecular Epidemiology and Risk Factors of Clostridium difficile ST81 Infection in a Teaching Hospital in Eastern China

BACKGROUND

The prevalence of Clostridium difficile causes an increased morbidity and mortality of inpatients, especially in Europe and North America, while data on C. difficile infection (CDI) are limited in China.

METHODS

From September 2014 to August 2019, 562 C. difficile isolates were collected from patients and screened for toxin genes. Multilocus sequence typing (MLST) and antimicrobial susceptibility tests by E-test and agar dilution method were performed. A case group composed of patients infected with sequence type (ST) 81 C. difficile was compared to the non-ST81 infection group and non CDI diarrhea patients for risk factor and outcome analyses.

RESULTS

The incidence of inpatients with CDI was 7.06 cases per 10,000 patient-days. Of the 562 C. difficile isolates, ST81(22.78%) was the predominant clone over this period, followed by ST54 (11.21%), ST3 (9.61%), and ST2 (8.72%). Toxin genotype tcdA+tcdB+cdt- accounted for 50.18% of all strains, while 29.54% were tcdA-tcdB+cdt- genotypes. Overall, no isolate was resistant to vancomycin, teicoplanin or daptomycin, and resistance rates to meropenem gradually decreased during these years. Although several metronidazole-resistant strains were isolated in this study, the MIC values decreased during this period. Resistance rates to moxifloxacin and clindamycin remained higher than those to the other antibiotics. Among CDI inpatients, longer hospitalization, usage of prednisolone, suffering from chronic kidney disease or connective tissue diseases and admission to emergency ward 2 or emergency ICU were significant risk factors for ST81 clone infection. All-cause mortality of these CDI patients was 4.92%(n=18), while the recurrent cases accounted for 5.74%(n=21). The 60-day mortality of ST81-CDI was significantly higher than non-ST81 infected group, while ST81 also accounted for most of the recurrent CDI cases.

CONCLUSION

This study revealed the molecular epidemiology and risk factors for the dominant C. difficile ST81 genotype infection in eastern China. Continuous and stringent surveillance on the emerging ST81 genotype needs to be initiated.

Impact of an automatic hospital probiotic protocol on Clostridioides (Clostridium) difficile infection (CDI) rates and CDI antibiotic usage in a community hospital setting

The aim of the present study was to see how widespread preventative use of the probiotic Saccharomyces boulardii via automatic protocol in hospitalised patients receiving antibacterials affected rates of hospital-associated Clostridioides (Clostridium) difficile infection (HA-CDI). Rates of HA-CDI appeared to be similar between the pre-protocol and protocol periods. Use of CDI treatment antibiotics (oral metronidazole and oral vancomycin) was also similar. Laboratory-confirmed isolation of S. boulardii from sterile body sites was identified in five patients during the protocol versus only one case in the pre-protocol years.

The engulfasome in C. difficile: Variations on protein machineries

Clostridioides difficile infection (CDI) continues to be a substantial healthcare burden, and the changing disease profile raises new challenges in CDI management, both in clinical settings and in the community. CDI is transmitted by spores, which are formed by a subset of the cell population where an asymmetric septum is formed. A full copy of the chromosome is transported into the smaller compartment which is then engulfed by the mother cell. After engulfment, multiple metabolic and morphological changes occur, eventually resulting in the release of the mature spore. Whilst studies in the model organism Bacillus subtilis have demonstrated the importance of the DMP and Q:AH machineries in engulfment, it is becoming clear that there are fundamental differences in the way the two organisms organise these machineries. As spores are the infectious agent in CDI, it is crucial to understand how these dormant cells are formed, and how sporulation can be prevented or disrupted with the view of reducing CDI. Here, we review the current literature on the DMP and Q:AH machineries in C. difficile, and how they compare and contrast to those of B. subtilis.

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Overview of the DMP and Q:AH engulfment machineries in C. difficile.

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Analyses of the conservation of DMP across Bacilli, Clostridia and other bacteria.

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Proposes a multi-protein complex required for engulfment: the engulfasome.

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Highlights differential arrangements of engulfasome in B. subtilis and C. difficile.

Molecular Characterization and Moxifloxacin Susceptibility of Clostridium difficile

In recent years, the incidence and severity of Clostridium difficile infections has increased. Additionally, resistance of C. difficile to frequently used antibiotics is rising. To improve our understanding of C. difficile, there is a need for molecular characterization of different strains and antibiotic resistance testing. We investigated the efficacy of GenoType CDiff kit (Hain Lifesciences) in identification of C. difficile and its various strains in northern Israel. The kit involves a molecular assay that detects C. difficile from stool samples or colonies and identifies the different strains and mutations in the gyrA gene that cause moxifloxacin resistance. Forty-nine C. difficile positive samples were examined by the kit following DNA extraction from both colonies and stool. The identification rate (95.9%) of C. difficile was much higher when DNA was extracted from colonies, compared to extraction from stool (46.9%). Low frequencies of ribotype027 strain (2%) and of ribotype078 strain (4%) were found. There was a high concordance between genotype (mutation in gyrA) and phenotype (Etest) for moxifloxacin resistance (Kappa = 0.72). A high percentage of moxifloxacin-resistant strains was found. Our findings indicate that the GenoType CDiff kit is very effective in characterization of C.difficile strains and less effective for identification of C. difficile directly from stool samples.

Faecal volatile biomarkers of Clostridium difficile infection

Care of patients with potential CDI can involve isolation and use of antibiotics, often before a definitive diagnosis is available, impacting healthcare resource and contributing to antibiotic resistance. There is anecdotal evidence that the faeces of CDI patients have a distinctive odour, while it is well-established that changes in the gut microbiota are associated with changes in the volatile organic compounds (VOC) produced. A total of twenty-four candidate volatile biomarkers were identified from a review of the literature including in vitro, animal and human studies. Using thermal desorption-gas chromatography-time-of flight mass spectrometry (TD-GC-ToFMS), VOC emission rates were determined on stored frozen stool samples from 53 CDI-positive and 53 CDI-negative patients with unexplained diarrhoea which had previously been diagnosed using enzymatic and nucleic acid amplification tests. Sample preparation was limited to placement of a subsample in an appropriate container. Compounds exhibiting a statistically significant difference (p < 0.05) in emission rate between the CDI-positive and-negative groups and a corresponding area under the receiver-operator characteristic curve (ROC) >0.7 were considered potentially indicative of CDI. Seven compounds were so identified: propan-1-ol (ROC 0.75), 3-methylbutanal (ROC 0.84), ethyl propionate (ROC 0.81), hexanoic acid (ROC 0.73), 4-methylphenol (ROC 0.81), dodecane (ROC 0.80) and indole (ROC 0.85). A number of potential volatile biomarkers of CDI can be sampled rapidly and with little prior preparation from faecal samples of patients with diarrhoea. Of these 4-methylphenol (p-cresol) is of particular interest as it has been anecdotally linked to CDI and is closely related to the biology and virulence of Clostridium difficile. This approach shows promise for the rapid, point-of-care diagnosis of CDI with good sensitivity and specificity.

Evaluation of a risk score to predict future Clostridium difficile disease using UK primary care and hospital data in Clinical Practice Research Datalink

We evaluated the applicability of a Clostridium difficile infection (CDI) risk index developed for patients at hospital discharge to identify persons at high-risk of CDI in a primary care population. This retrospective observational study used data from the UK Clinical Practice Research Datalink, linked with Hospital Episodes Statistics. The risk index was based on the following patient characteristics: age, previous hospitalizations, days in hospital, and prior antibiotics use. Individual risk scores were calculated by summing points assigned to pre-defined categories for each characteristic. We assessed the association of risk factors with CDI by multivariate logistic regression. The estimated CDI incidence rate was 4/10,000 and 2/10,000 person-years in 2008 and 2012, respectively. On an index with a maximal risk of 19, a cut-off for high risk of ≥7 had sensitivity, specificity and positive predictive values of 80%, 87% and 12%, respectively. A high-risk person had a ~ 35% higher risk of CDI than a low-risk person. Multivariate risk factor analysis indicated a need to reconsider the relative risk scores. The CDI risk index can be applied to the UK primary care population and help identify study populations for vaccine development studies. Reassessing the relative weights assigned to risk factors could improve the index performance in this setting.

Prevalence, characteristics and antimicrobial susceptibility patterns of Clostridioides difficile isolated from hospitals in Iran

OBJECTIVES

Clostridioides (previously Clostridium) difficile is a major growing cause of nosocomial diarrhoea known as C. difficile infection (CDI). This study investigated the prevalence and antimicrobial resistance patterns of C. difficile isolated from patients suffering from diarrhoea in Iran between 2016-2018.

METHODS

A total of 151 stool specimens were collected and were screened for the presence of C. difficile. Specimens were examined for toxins by culture, enzyme immunoassay (EIA) and PCR. Antimicrobial susceptibility testing was performed for 12 antibiotics (metronidazole, vancomycin, clindamycin, tetracycline, erythromycin, ciprofloxacin, levofloxacin, moxifloxacin, fusidic acid, piperacillin, piperacillin/tazobactam and rifampicin) by the disk diffusion method according to the guidelines of the CLSI, EUCAST and CA-SFM.

RESULTS

Of 151 stool specimens, 66 (43.7%) were positive for C. difficile by PCR, whereas 2 (1.3%) were only positive for C. difficile toxins based on EIA. A total of 292 clostridial isolates were obtained from specimens by culture, of which 133 (45.5%) were finally confirmed as C. difficile by PCR. Of 121 isolates resistant to at least one antibiotic, 107 (88.4%) were resistant to three or more antimicrobials and thus were defined as multidrug-resistant (MDR). Different and diverse resistance patterns to the antimicrobial drugs were seen among the isolates.

CONCLUSION

This is the first report of the isolation of C. difficile from different governmental hospitals of Iran and indicates that CDI might be an important nosocomial infection in different hospital wards. Moreover, this study provides a comprehensive picture of the MDR phenotype characteristics of C. difficile isolates in Iran.

Generation of Markerless Deletions in the Nosocomial Pathogen Clostridium difficile by Induction of DNA Double-Strand Breaks

Most sequenced bacterial genomes contain genes encoding proteins of unknown or hypothetical function. To identify a phenotype for mutations in such genes, deletion is the preferred method for mutagenesis because it reduces the likelihood of polar effects, although it does not eliminate the possibility. Allelic exchange to produce deletions is dependent on the length of homologous regions used to generate merodiploids. Shorter regions of homology resolve at lower frequencies. The work presented here demonstrates the utility of inducing DNA double-strand breaks to increase the frequency of merodiploid resolution in Clostridium difficile. Using this approach, we reveal the roles of two genes, encoding homologues of AddAB, in survival following DNA damage. The method is readily applicable to the production of deletions in C. difficile and expands the toolbox available for genetic analysis of this important anaerobic pathogen.

Clostridium difficile is an important nosocomial pathogen associated with potentially fatal disease induced by the use of antibiotics. Genetic characterization of such clinically important bacteria is often hampered by lack of availability of suitable tools. Here, we describe the use of I-SceI to induce DNA double-strand breaks, which increase the frequency of allelic exchange and enable the generation of markerless deletions in C. difficile. The usefulness of the system is illustrated by the deletion of genes encoding putative AddAB homologues. The ΔaddAB mutants are sensitive to ultraviolet light and the antibiotic metronidazole, indicating a role in homologous recombination and the repair of DNA breaks. Despite the impairment in recombination, the mutants are still proficient for induction of the SOS response. In addition, deletion of the fliC gene, and subsequent complementation, reveals the importance of potential regulatory elements required for expression of a downstream gene encoding the flagellin glycosyltransferase.

IMPORTANCE Most sequenced bacterial genomes contain genes encoding proteins of unknown or hypothetical function. To identify a phenotype for mutations in such genes, deletion is the preferred method for mutagenesis because it reduces the likelihood of polar effects, although it does not eliminate the possibility. Allelic exchange to produce deletions is dependent on the length of homologous regions used to generate merodiploids. Shorter regions of homology resolve at lower frequencies. The work presented here demonstrates the utility of inducing DNA double-strand breaks to increase the frequency of merodiploid resolution in Clostridium difficile. Using this approach, we reveal the roles of two genes, encoding homologues of AddAB, in survival following DNA damage. The method is readily applicable to the production of deletions in C. difficile and expands the toolbox available for genetic analysis of this important anaerobic pathogen.

Impact evaluation of a Critical Pathway for patients with Clostridium difficile infection: A pre-post analysis in a Third Level Referral Center

BACKGROUND

Clostridium Difficile Infections (CDIs) have been increasing both in incidence and in severity, representing a big public health concern.

AIM

The aim of this study was to evaluate the impact of a recently implemented Critical Pathway (CP) focused on patients with CDI in an Italian Teaching Hospital.

METHODS

The CP implementation consisted of intervention aimed to faster diagnosis and appropriateness in admission and discharge point of care; activation of a multidisciplinary team; staff training; information to patients and caregivers. In a pre-post retrospective observational study, volume, process and outcome indicators were analyzed.

FINDINGS

A total of 228 patients (128 in 2013 and 100 in 2016) were included. A decrease in the absolute number of access to the Emergency Department (p=0.02) and an increase in hospitalization in more appropriate ward (ie gastroenterology ward, p<0.001) were found. The median hospital length of stay decreased from 20.5 (12.5-31) days in 2013 to 16.5 (7-31) days in 2016 (p=0.05). With regards to outcome indicators, an increase of discharge to home and a decrease of discharge to long term facilities were showed (p=0.01 both). Despite a reduction, no statically significant differences in mortality between 2013 and 2016 were revealed by the analysis.

CONCLUSION

In conclusion, we found quality improvement in patient hospital management. Our experience confirms that the implementation of the CP increases the appropriateness in hospital quality of care.

Fecal microbiota transplantation: donor relation, fresh or frozen, delivery methods, cost-effectiveness

Fecal microbiota transplantation (FMT) has evolved into a robust and efficient means for treating recurrent Clostridium difficile infection (CDI). Our narrative review looks at the donor selection, preparation, delivery techniques and cost-effectiveness of FMT. We searched electronic databases, including PubMed, MEDLINE, Google Scholar, and Cochrane Databases, for studies that compared the biological effects of donor selection, fresh or frozen fecal preparation, and various delivery techniques. We also evaluated the cost-effectiveness and manually searched references to identify additional relevant studies. Overall, there is a paucity of studies that directly compare outcomes associated with related and non-related stool donors. However, inferences from prior studies indicate that the success of FMT does not depend on the donor-patient relationship. Over time, the use of unrelated donors has increased because of the formation of stool banks and the need to save processing time and capital. However, longitudinal studies are needed to clarify the optimal freezing time before microbial function declines. Several FMT techniques have been developed, such as colonoscopy, enema, nasogastric or nasojejunal tubes, and capsules. The comparable and high efficacy of FMT capsules, combined with their convenience, safety and aesthetically tolerable mode of delivery, makes it an attractive option for many patients. Cost-effective models comparing these various approaches support the use of FMT via colonoscopy as being the best strategy for the treatment of recurrent CDI.

Ridinilazole: a novel antimicrobial for Clostridium difficile infection

Clostridium difficile (C. difficile) infection remains a global healthcare threat worldwide and the limited options available for its treatment are of particular concern. Ridinilazole is one potential future agent, as it demonstrates rapid bactericidal activity against C. difficile. Current studies show that ridinilazole has a lower propensity for collateral damage to the gut microbiome and appears to diminish the production of C. difficile toxins. Results from phase II studies demonstrate that patients receiving ridinilazole had a higher sustained clinical response compared with patients receiving vancomycin (66.7% vs. 42.4%; P=0.0004). Adverse reactions were similar between ridinilazole and vancomycin (40% vs. 56%, respectively), with most being gastrointestinal-related. Nausea (20%) and abdominal pain (12%) were the most commonly reported adverse reactions associated with ridinilazole. Phase II study results are promising and future availability of phase III trial results will help further delineate the role and value of ridinilazole.

N-Deacetylases required for muramic-δ-lactam production are involved in Clostridium difficile sporulation, germination, and heat resistance

Spores are produced by many organisms as a survival mechanism activated in response to several environmental stresses. Bacterial spores are multilayered structures, one of which is a peptidoglycan layer called the cortex, containing muramic-δ-lactams that are synthesized by at least two bacterial enzymes, the muramoyl-l-alanine amidase CwlD and the N-deacetylase PdaA. This study focused on the spore cortex of Clostridium difficile, a Gram-positive, toxin-producing anaerobic bacterial pathogen that can colonize the human intestinal tract and is a leading cause of antibiotic-associated diarrhea. Using ultra-HPLC coupled with high-resolution MS, here we found that the spore cortex of the C. difficile 630Δerm strain differs from that of Bacillus subtilis Among these differences, the muramic-δ-lactams represented only 24% in C. difficile, compared with 50% in B. subtilis CD630_14300 and CD630_27190 were identified as genes encoding the C. difficile N-deacetylases PdaA1 and PdaA2, required for muramic-δ-lactam synthesis. In a pdaA1 mutant, only 0.4% of all muropeptides carried a muramic-δ-lactam modification, and muramic-δ-lactams were absent in the cortex of a pdaA1-pdaA2 double mutant. Of note, the pdaA1 mutant exhibited decreased sporulation, altered germination, decreased heat resistance, and delayed virulence in a hamster infection model. These results suggest a much greater role for muramic-δ-lactams in C. difficile than in other bacteria, including B. subtilis In summary, the spore cortex of C. difficile contains lower levels of muramic-δ-lactams than that of B. subtilis, and PdaA1 is the major N-deacetylase for muramic-δ-lactam biosynthesis in C. difficile, contributing to sporulation, heat resistance, and virulence.

Co-infection of Clostridioides (Clostridium) difficile GMU1 and Bacillus cereus GMU2 in one patient in Guizhou, China

Clostridioides (Clostridium) difficile and Bacillus cereus infections are frequently reported in human individually. However, co-infection of both pathogens in human is extremely rare. In the present study, we reported a case of human enteric disease caused by co-infection of C. difficile and B. cereus in Guizhou, China. The 16S rDNA sequencing result showed that C. difficile GMU1 and B. cereus GMU2 were most related to C. difficile ATCC 9689 and B. cereus ATCC 14579. The toxin genotype of C. difficile GMU1 and B. cereus GMU2 were tcdA⁺tcdB⁺tcdC⁺ and bceT⁺nheA⁺nheB⁺nheC⁺, respectively. Cytotoxicity assay demonstrated that C. difficile GMU1 produced significantly higher toxin B compare to C. difficile 630 stain. In contrast, B. cereus GMU2 has comparable NheA toxin productivity compare to previous report. The antimicrobial susceptibility test showed that the combination of ampicillin and vancomycin was most efficient to inhibit both C. difficile GMU1 and B. cereus GMU2.

Comparative epidemiology of Clostridium difficile infection: England and the USA

Objective

To examine whether there is an epidemiological difference between Clostridium difficile infection (CDI) inpatient populations in England and the United States.

Design

A cross-sectional study.

Setting

National administrative inpatient discharge data from England (Hospital Episode Statistics) and the USA (National Inpatient Sample) in 2012.

Participants

De-identifiable non-obstetric inpatient discharges from the national datasets were used to estimate national CDI incidence in the United States and England using ICD9-CM(008.45) and ICD10(A04.7) respectively.

Main outcome measures

The rate of CDI was calculated per 100 000 population using national population estimates. Rate per 100 000 inpatient discharges was also calculated separated by primary and secondary diagnosis of CDI. Age, sex and Elixhauser comorbidities profiles were examined.

Results

The USA had a higher rate of CDI compared to England: 115.1/100 000 vs. 19.3/100 000 population (P < 0.001). CDI age profiles differed between the countries (P < 0.001): in England, patients ≥75 years constitute a larger proportion of CDI cases, whilst those aged 25-70 constitute more cases in the US (P < 0.001). Overall adjusted odds of CDI in females compared to males was elevated in both England (odds ratios (OR) 1.26 95% CI [1.21,1.31] P < 0.001) and the USA (OR 1.20 95% CI [1.18,1.22] P < 0.001). The proportion of CDI patients with comorbidities was greater in the USA compared to England apart from dementia, which was greater in England (9.63% vs. 1.25%, P < 0.0001).

Conclusions

The 2012 inpatient CDI rate within the USA was much higher than in England. Age and comorbidity profiles also differed between CDI patients in both countries. The reasons for this are likely multi-factorial but may reflect national infection control policy.

Economic Burden of Clostridium difficile Infection in European Countries

Clostridium difficile infection (CDI) remains a considerable challenge to health care systems worldwide. Although CDI represents a significant burden on healthcare systems in Europe, few studies have attempted to estimate the consumption of resources associated with CDI in Europe. The reported extra costs attributable to CDI vary widely according to the definitions, design, and methodologies used, making comparisons difficult to perform. In this chapter, the economic burden of healthcare facility-associated CDI in Europe will be assessed, as will other less explored areas such as the economic burden of recurrent CDI, community-acquired CDI, pediatric CDI, and CDI in outbreaks.

Impact of recurrent Clostridium difficile infection: hospitalization and patient quality of life

Objectives

Data quantifying outcomes of recurrent Clostridium difficile infection (rCDI) are lacking. We sought to determine the UK hospital resource use and health-related quality of life (HRQoL) associated with rCDI hospitalizations.

Patients and methods

A non-interventional study in six UK acute hospitals collected retrospective clinical and resource use data from medical records of 64 adults hospitalized for rCDI and 64 matched inpatient controls with a first episode only (f)CDI. Patients were observed from the index event (date rCDI/fCDI confirmed) for 28 days (or death, if sooner); UK-specific reference costs were applied. HRQoL was assessed prospectively in a separate cohort of 30 patients hospitalized with CDI, who completed the EQ-5D-3L questionnaire during their illness.

Results

The median total management cost (post-index) was £7539 and £6294 for rCDI and fCDI, respectively (cost difference, P = 0.075); median length of stay was 21 days and 15.5 days, respectively (P = 0.269). The median cost difference between matched rCDI and fCDI cases was £689 (IQR=£1873-£3954). Subgroup analysis demonstrated the highest median costs (£8542/patient) in severe rCDI cases. CDI management costs were driven primarily by hospital length of stay, which accounted for >85% of costs in both groups. Mean EQ-5D index values were 46% lower in CDI patients compared with UK population values (0.42 and 0.78, respectively); EQ visual analogue scale scores were 38% lower (47.82 and 77.3, respectively).

Conclusions

CDI has considerable impact on patients and healthcare resources. This multicentre study provides a contemporaneous estimate of the real-world UK costs associated with rCDI management, which are substantial and comparable to fCDI costs.

Molecular epidemiology of Clostridium difficile in two tertiary care hospitals in Shandong Province, China

PURPOSE

The incidence and severity of Clostridium difficile infection (CDI) have markedly increased over the past decade. However, there is very limited epidemiological data on CDI in China so far, specifically no data in Shandong Province. The aim of this study was to evaluate diagnostic algorithm for CDI and to gain data on molecular epidemiology of CDI in the Shandong Province of China.

MATERIALS AND METHODS

Nonrepetitive unformed fecal specimens (n=504) were investigated by the glutamate dehydrogenase (GDH), C. difficile toxin A&B (CDAB) tests and toxigenic culture. Furthermore, 85 isolates were characterized by toxin gene detection, multilocus sequence typing, ribotyping and antimicrobial susceptibility testing.

RESULTS

The algorithm of combining GDH and CDAB tests could define diagnosis of 54.2% CDI cases and excluded 90% of non-CDI. Further adding the toxigenic culture to the algorithm enhanced the detection sensitivity to 100%. Toxigenic strains comprised 84.7% of isolates, including A+B+CDT- (71.8%, 61/85), A-B+CDT- (11.8%, 10/85) and A+B+CDT+ (1.2%, 1/85) isolates. RT046/ST35 (13.9%, 10/72), RT014/ST2 (12.5%, 9/72) and RT017/ST37 (12.5%, 9/72) were the more common genotypes among toxigenic C. difficile strains. The clinical severity score of A-B+CDT- toxin genes genotype (3.50±0.85) was significantly higher than the A+B+CDT- type (2.59±0.93) (P<0.05). RT046/ST35 isolates were highly prevalent and had high clinical severity scores (3.80±0.92). Variations in resistance from different sequence types (STs) were observed. Toxigenic strains showed higher resistance rates to erythromycin, clindamycin and ciprofloxacin compared to nontoxigenic strains (P<0.05).

CONCLUSION

The epidemiology of C. difficile in Shandong Province differed from other regions in China. Comprehensive optimized diagnosis strategy and continuous surveillance should be established and applied in order to curb the spread of toxigenic C. difficile strains, especially for hospitalized patients.