European Society of Clinical Microbiology and Infectious Diseases: update of the diagnostic guidance document for Clostridium difficile infection

Clostridioides difficile epidemiology in the Middle and the Far East

OBJECTIVES

Clostridioides difficile is an important pathogen of healthcare-associated gastrointestinal infections. Recently, an increased number of C. difficile infection (CDI) surveillance data has been reported from Asia. The aim of this review is to summarize the data on the prevalence, distribution and molecular epidemiology of CDI in the Middle and the Far East.

METHODS

Literature was drawn from a search of PubMed up to September 30, 2021.

RESULTS

The meta-analysis of data from 111 studies revealed the pooled CDI prevalence rate in the Middle and the Far East of 12.4% (95% CI 11.4-13.3); 48 studies used PCR for CDI laboratory diagnoses. The predominant types (RT)/sequence type (ST) differ between individual countries (24 studies, 14 countries). Frequently found RTs were 001, 002, 012, 017, 018 and 126; RT017 was predominant in the Far East. The epidemic RT027 was detected in 8 countries (22 studies), but its predominance was reported only in three studies (Israel and Iran). The contamination of vegetable and meat or meat products and/or intestinal carriage of C. difficile in food and companion animals have been reported; the C. difficile RTs/STs identified overlapped with those identified in humans.

CONCLUSIONS

A large number of studies on CDI prevalence in humans from the Middle and the Far East have been published; countries with no available data were identified. The number of studies on C. difficile from non-human sources is limited. Comparative genomic studies of isolates from different sources are needed.

Clostridioides (Clostridium) difficile in children with diarrhoea in Vietnam

BACKGROUND

Clostridioides (Clostridium) difficile commonly causes hospital-acquired infection which can range from mild diarrhoea to life-threatening toxic megacolon and even death. Reports on C. difficile infection (CDI) in Vietnam are limited, so this study was designed to evaluate the prevalence, molecular epidemiology and antimicrobial susceptibility of C. difficile isolated from children with diarrhoea in Vietnam. Infants are often colonised with C. difficile and it was hypothesised that those colonising strains would represent strains of C. difficile circulating in the hospital/region at the time, however, this was not an attempt to determine if C. difficile was the cause of the diarrhoea.

METHODS

Diarrhoeal stool samples collected at two children's hospitals in northern Vietnam from 1^st October 2020 to 28^th February 2021 were transported to Perth, Western Australia, for culture of C. difficile and further investigations on isolates; PCR ribotyping, toxin gene profiling and antimicrobial susceptibility testing.

RESULTS

From these hospitals, 370 diarrhoeal stool samples were collected, most from children aged 1-15 months (71.9%; 266/370). The overall prevalence of C. difficile in stool samples from children aged ≤16 years was 37.8% (140/370) and the highest prevalence was in the 2-12 months age group (52.9%; 74/140). In total, 151 isolates of C. difficile were recovered; the proportion of toxigenic isolates was 16.6% (25/151). Of the 25 toxigenic C. difficile isolates, the toxin gene profiles A⁺B⁺CDT^- and A^-B⁺CDT^- comprised 72% and 28%, respectively. The four most prevalent C. difficile ribotypes (RTs) were QX 011 (25/151), RT 010 (25/151), QX 107 (12/151) and RT 012 (11/151). All isolates were susceptible to vancomycin, metronidazole and fidaxomicin, while there was significant resistance to clindamycin (90.1%), and some to moxifloxacin (6.6%) and rifaximin (3.3%).

CONCLUSION

The prevalence of C. difficile in children with diarrhoea was high (37.8%) although the proportion of toxigenic strains was comparatively low. The clinical significance of any isolate needs to be determined.

Nationwide Survey for Current Status of Laboratory Diagnosis of Clostridioides difficile Infection in Korea

BACKGROUND

The interest in Clostridioides difficile infection (CDI) has increased, and the choice of assays became wider since the first national survey in Korea on CDI diagnosis in 2015. We conducted a survey of the domestic CDI assays with more varied questions to understand the current situation in Korea.

METHODS

In April 2018, about 50 questions on the current status of CDI assays and details on implementation and perceptions were written, and a survey questionnaire was administered to laboratory medicine specialists in 200 institutions.

RESULTS

One-hundred and fifty institutions responded to the questionnaire, of which 90 (60.0%) including one commercial laboratory, performed CDI assays. The toxin AB enzyme immunoassay (toxin AB EIA), nucleic acid amplification test (NAAT), and C. difficile culture, glutamate dehydrogenase assay, alone or in combination with other assays, were used in 75 (84.3%), 52 (58.4%), 35 (36.0%), and 23 (25.8%), respectively, and 65 (73.0%) institutions performed a combination of two or more assays. The sensitivity of toxin AB EIA was more negatively perceived, and that on specificity was more positively perceived. The perception of sensitivity and specificity of NAAT was mostly positive. Perception on the algorithm test projected it as useful but in need of countermeasures. Sixty-three (73.3%) institutions responded that they performed surveillance on CDI.

CONCLUSION

This study provides useful evidence on the current status of CDI laboratory diagnosis in Korea as well as on items that require improvement and is thought to aid in standardizing and improving the CDI laboratory diagnosis in Korea.

Bezlotoxumab for Prevention of Recurrent Clostridioides difficile Infection With a Focus on Immunocompromised Patients

OBJECTIVES

Approximately 25% of patients with Clostridioides difficile infection (CDI) will experience recurrence, which is greater in immunocompromised patients. We report experience with an institutional guideline targeting high-risk immunocompromised patients.

METHODS

This was a retrospective cohort of consecutive patients with CDI who met institutional criteria for bezlotoxumab due to high risk for recurrent CDI between June 1, 2017, and November 30, 2018. The primary endpoint of recurrent CDI within 12 weeks was compared between patients who received the standard of care (SoC) plus or minus bezlotoxumab.

RESULTS

Twenty-three patients received bezlotoxumab infusion plus SoC and were compared to 30 SoC patients. 84% of patients were immunocompromised and 54.7% were transplant recipients. The primary endpoint occurred in 13% of bezlotoxumab patients compared to 23.3% of SoC patients. No serious adverse effects were identified.

CONCLUSION

Bezlotoxumab was associated with a meaningful reduction in recurrent CDI in this cohort largely comprising immunocompromised and transplant patients. Larger studies are warranted to evaluate bezlotoxumab in this population.

An open randomized multicentre Phase 2 trial to assess the safety of DAV132 and its efficacy to protect gut microbiota diversity in hospitalized patients treated with fluoroquinolones

BACKGROUND

DAV132 (colon-targeted adsorbent) has prevented antibiotic-induced effects on microbiota in healthy volunteers.

OBJECTIVES

To assess DAV132 safety and biological efficacy in patients.

PATIENTS AND METHODS

An open-label, randomized [stratification: fluoroquinolone (FQ) indication] multicentre trial comparing DAV132 (7.5 g, 3 times a day, orally) with No-DAV132 in hospitalized patients requiring 5-21 day treatment with FQs and at risk of Clostridioides difficile infection (CDI). FQ and DAV132 were started simultaneously, DAV132 was administered for 48 h more, and patients were followed up for 51 days. The primary endpoint was the rate of adverse events (AEs) independently adjudicated as related to DAV132 and/or FQ. The planned sample size of 260 patients would provide a 95% CI of ±11.4%, assuming a 33% treatment-related AE rate. Plasma and faecal FQ concentrations, intestinal microbiota diversity, intestinal colonization with C. difficile, MDR bacteria and yeasts, and ex vivo resistance to C. difficile faecal colonization were assessed.

RESULTS

Two hundred and forty-three patients (median age 71 years; 96% with chronic comorbidity) were included (No-DAV132, n = 120; DAV132, n = 123). DAV132- and/or FQ-related AEs did not differ significantly: 18 (14.8%) versus 13 (10.8%) in DAV132 versus No-DAV132 patients (difference 3.9%; 95% CI: -4.7 to 12.6). Day 4 FQ plasma levels were unaffected. DAV132 was associated with a >98% reduction in faecal FQ levels (Day 4 to end of treatment; P < 0.001), less impaired microbiota diversity (Shannon index; P = 0.003), increased ex vivo resistance to C. difficile colonization (P = 0.0003) and less frequent FQ-induced VRE acquisition (P = 0.01).

CONCLUSIONS

In FQ-treated hospitalized patients, DAV132 was well tolerated, and FQ plasma concentrations unaffected. DAV132 preserved intestinal microbiota diversity and C. difficile colonization resistance.

Is the Medium Still the Message? Culture-Independent Diagnosis of Gastrointestinal Infections

Infectious diarrhea is caused by a variety of pathogens, including viruses, bacteria, and parasitic organisms. Though the causative agent of diarrhea has historically been evaluated via stool cultures, recently, culture-independent diagnostic tests (CIDT) have been developed and utilized with increasing frequency. Current practice guidelines recommend their use as adjuncts to stool cultures for diagnosing acute and chronic diarrhea. The three principal CIDT are microscopy, enzyme-based immunoassays (EIAs), and molecular based polymerase chain reaction (PCR). This review explores the common causes of infectious diarrhea, the basics of stool culture, the diagnostic utility of these three culture-independent modalities, and the strengths and weaknesses of all currently available clinical techniques. It also outlines considerations for specific populations including returning travelers and those with inflammatory bowel disease.

Flagellum and toxin phase variation impacts intestinal colonization and disease development in a mouse model of Clostridioides difficile infection

Clostridioides difficile is a major nosocomial pathogen that can cause severe, toxin-mediated diarrhea and pseudomembranous colitis. Recent work has shown that C. difficile exhibits heterogeneity in swimming motility and toxin production in vitro through phase variation by site-specific DNA recombination. The recombinase RecV reversibly inverts the flagellar switch sequence upstream of the flgB operon, leading to the ON/OFF expression of flagellum and toxin genes. How this phenomenon impacts C. difficile virulence in vivo remains unknown. We identified mutations in the right inverted repeat that reduced or prevented flagellar switch inversion by RecV. We introduced these mutations into C. difficile R20291 to create strains with the flagellar switch "locked" in either the ON or OFF orientation. These mutants exhibited a loss of flagellum and toxin phase variation during growth in vitro, yielding precisely modified mutants suitable for assessing virulence in vivo. In a hamster model of acute C. difficile infection, the phase-locked ON mutant caused greater toxin accumulation than the phase-locked OFF mutant but did not differ significantly in the ability to cause acute disease symptoms. In contrast, in a mouse model, preventing flagellum and toxin phase variation affected the ability of C. difficile to colonize the intestinal tract and to elicit weight loss, which is attributable to differences in toxin production during infection. These results show that the ability of C. difficile to phase vary flagella and toxins influences colonization and disease development and suggest that the phenotypic variants generated by flagellar switch inversion have distinct capacities for causing disease.

Toxin-Producing Klebsiella oxytoca in Healthy Infants: Commensal or Pathobiont?

OBJECTIVES

Klebsiella oxytoca is a gastrointestinal pathobiont with the potential to produce the toxins tilivalline and tilimycin, which cause antibiotic-associated hemorrhagic colitis. Overgrowth of toxigenic K oxytoca has recently been implicated in necrotizing enterocolitis. K oxytoca colonizes 2-9% of healthy adults, however, there is no systematic data on colonization in healthy children. We investigated K oxytoca colonization and its toxigenic properties in healthy infants.

METHODS

We sampled stool of healthy infants and determined K oxytoca colonization using stool culture and PCR (pehX). Toxin in stool was measured with HPLC/high-resolution mass spectrometry. K oxytoca isolates were typed using multi-locus sequence typing (MLST) and K oxytoca toxin PCR (npsA/B). Cytotoxin production of isolates was analyzed by MTT assay.

RESULTS

K oxytoca was detected in 30 of 61 infants (49%) using stool culture and in 45 of 61 (73%) using PCR (pehX). Toxin marker PCR (npsA/B) was positive in 66% of stool samples positive for K oxytoca PCR. Stool toxin levels were too low for quantitation but traces of tilivalline were detected. Contrarily, 49% of K oxytoca isolates demonstrated toxicity in the MTT assay. MLST revealed 36 distinct sequence types affiliated with all known K oxytoca sequence type clusters (A, B1 and B2).

CONCLUSIONS

More than 70% of healthy infants were colonized with K oxytoca. Toxin quantities in stool of colonized healthy infants were below detection level, yet half of the isolates produced toxin in vitro demonstrating their pathobiont potential. The high occurrence of toxigenic K oxytoca in healthy infants has to be considered for future disease association studies.

Standardisation and validation of an in-house quantitative real-time polymerase chain reaction (qPCR) assay for the diagnosis of Clostridioides difficile infection

OBJECTIVES

Clostridioides difficile is an emerging enteric pathogen that causes nosocomial diarrhoea in adults. The excessive cost of commercial molecular tests restricts the access of developing countries to its diagnosis. This study aimed to develop and validate in-house quantitative polymerase chain reaction (qPCR) targeting the C. difficile toxin B gene (tcdB) using two detection methodologies-SYBR Green and hydrolysis probes-for the diagnosis of C. difficile infection (CDI).

METHODS

Glutamate dehydrogenase (GDH) plus toxigenic culture was the standard reference diagnostic method. The SYBR Green method and hydrolysis probes were used to study 392 samples simultaneously to assess the diagnostic value of these real-time PCR assays in detecting CDI from clinical samples.

RESULTS

The SYBR Green and hydrolysis probe assays showed 97.9% and 87.5% sensitivity; 99.1% and 100.0% specificity; 94.0% and 100.0% positive predictive value; 99.7% and 98.3% negative predictive value; and 99.0% and 98.5% accuracy, respectively.

CONCLUSIONS

The two qPCR methodologies evaluated could offer an adequate tool as part of an algorithm in the laboratory diagnosis of CDI.

Updates and Opinions in Diagnosis and Treatment of Clostridiodes difficile in Pediatrics

Purpose of review

Clostridiodes difficile infection (CDI) has unique challenges for diagnosis and treatment in pediatrics. Though new antibiotics and biologics are being approved or developed for adults, most of the pediatric therapies still rely on multiple or extended antibiotic courses. This review aims to highlight emerging evidence and our clinical experience with CDI in children and can help inform readers' approach to pediatric CDI.

Recent findings

Use of fidaxomicin for CDI in pediatrics has been shown to be to be non-inferior to vancomycin and is associated with higher global cure rates and decreased risk of recurrence. Fecal microbiota transplant is a successful emerging therapy with cure rates of up to 90%, though safety alerts should be noted. Diagnostic laboratory testing for C. difficile remains a challenge as it still cannot definitively distinguish between colonization and true infection, and this is particularly relevant to pediatric patients as they have the highest rates of colonization.

Summary

The diagnosis and treatment of C. difficile infection in pediatrics remain challenging and recommendations lag behind advances made in the adult field. Recent data suggests that use of fidaxomicin both as treatment of first episode or recurrences may be beneficial in pediatrics just as in adults. At an experienced center, FMT is associated with high cure rates. Bezlotuxumab a monoclonal antibody to toxin B that is already recommended for use in adults is being studied in children and should be available for clinical use soon. Oral vancomycin prophylaxis is also an emerging strategy for high-risk patients. Finally, a possible vaccine may be on the horizon for pediatrics.

Healthcare-associated Clostridioides difficile infection during the COVID-19 pandemic in a tertiary care hospital in Romania

Introduction. Information on healthcare-associated C.difficile infection (HA-CDI) in COVID-19 patients is limited. We aimed to assess the characteristics of HA-CDI acquired during and before the COVID-19 pandemic. Methods. We conducted a retrospective study in a tertiary care hospital, in which since March 2020 exclusively COVID-19 patients are hospitalized. We compared HA-CDI adult patients hospitalized in March 2020-February 2021 with those hospitalized during the same period in 2017-2018. Results. We found 51 cases during 2020-2021 (COVID-19 group), incidence 5.6/1000 adult discharge and 99 cases during 2017-2018 (pre-COVID-19 group), incidence 6.1/1000 adult discharge (p=0.6). The patients in COVID-19 group compared to pre-COVID-19 group were older (median age 66 vs 62 years), with similar rate of comorbidities, but with higher rate of cardiovascular diseases (62.7% vs 42.4%) and less immunosuppression (21.6% vs 55.6%), they had a higher proton pump inhibitors use (94.1% vs 32.3%), and a longer hospitalization (median 19 vs 14 days). Eighty-five (85.9%) patients in pre-COVID-19 group versus 44 (86.3%) patients in COVID-19 group received antimicrobial treatment - mainly cephalosporins (34,1%), quinolones (22,3%) and glycopeptides (21,1%) in pre-COVID-19 group and mainly cephalosporins and macrolides (63,6% each) in COVID-19 group. We found four HA-CDI-related deaths in pre-COVID-19 group and none in the COVID-19 group. Conclusions. The HA-CDI incidence in COVID-19 group did not change versus the same period of time during 2017-2018. The antibiotic use was the most important factor associated with HA-CDI. We identified a high use of broad-spectrum antibiotics despite the lack of empirical antimicrobial recommendations in COVID-19.

Readmission, healthcare consumption, and mortality in Clostridioides difficile infection hospitalizations: a nationwide cohort study

OBJECTIVE

Despite being the most common healthcare-related infection in the US, nationwide data on readmission, healthcare consumption, and mortality in Clostridioides difficile infection (CDI) remain limited. We examined these outcomes in a US-based cohort of patients with CDI.

METHODS

We queried the 2017 Nationwide Readmission Database using ICD-10-CM codes to identify all adult patients admitted with a principal diagnosis of CDI. Primary outcomes were 30- and 90-day readmission rates. Secondary outcomes included mortality rates and healthcare consumption.

RESULTS

Of the 83,865 patients discharged from an index hospitalization for CDI, 22.37% were readmitted within 30 days, and an additional 15.01% were readmitted within 90 days. Recurrent CDI was responsible for more than 30% of readmissions at both 30 and 90 days. Compared to the index hospitalization, readmissions were characterized by higher mortality (1.41% index vs. 4.86% 30-day vs. 4.40% 90-day) and increased hospital length of stay and charges. Medicaid insurance (HR 1.16), cirrhosis (HR 1.31), Type 1 diabetes mellitus (HR 1.38), and end-stage renal disease (HR 1.36) were independently associated with 30-day readmission (all p < 0.01), with similar findings in 90-day readmissions.

CONCLUSIONS

In a large cohort of patients hospitalized for CDI, we found that approximately 1 in 5 were readmitted within 30-days, and more than 1 in 3 within 90-days. Readmission was characterized by increased mortality and greater healthcare consumption. Additionally, we found independent associations for readmission that may help identify patients at high-risk. Prospective investigation is needed to identify means to reduce the healthcare consumption and mortality in CDI.

European Society of Clinical Microbiology and Infectious Diseases: 2021 update on the treatment guidance document for Clostridioides difficile infection in adults

SCOPE

In 2009, the European Society of Clinical Microbiology and Infectious Diseases (ESCMID) published the first treatment guidance document for Clostridioides difficile infection (CDI). This document was updated in 2014. The growing literature on CDI antimicrobial treatment and novel treatment approaches, such as faecal microbiota transplantation (FMT) and toxin-binding monoclonal antibodies, prompted the ESCMID study group on C. difficile (ESGCD) to update the 2014 treatment guidance document for CDI in adults.

METHODS AND QUESTIONS

Key questions on CDI treatment were formulated by the guideline committee and included: What is the best treatment for initial, severe, severe-complicated, refractory, recurrent and multiple recurrent CDI? What is the best treatment when no oral therapy is possible? Can prognostic factors identify patients at risk for severe and recurrent CDI and is there a place for CDI prophylaxis? Outcome measures for treatment strategy were: clinical cure, recurrence and sustained cure. For studies on surgical interventions and severe-complicated CDI the outcome was mortality. Appraisal of available literature and drafting of recommendations was performed by the guideline drafting group. The total body of evidence for the recommendations on CDI treatment consists of the literature described in the previous guidelines, supplemented with a systematic literature search on randomized clinical trials and observational studies from 2012 and onwards. The Grades of Recommendation Assessment, Development and Evaluation (GRADE) system was used to grade the strength of our recommendations and the quality of the evidence. The guideline committee was invited to comment on the recommendations. The guideline draft was sent to external experts and a patients' representative for review. Full ESCMID endorsement was obtained after a public consultation procedure.

RECOMMENDATIONS

Important changes compared with previous guideline include but are not limited to: metronidazole is no longer recommended for treatment of CDI when fidaxomicin or vancomycin are available, fidaxomicin is the preferred agent for treatment of initial CDI and the first recurrence of CDI when available and feasible, FMT or bezlotoxumab in addition to standard of care antibiotics (SoC) are preferred for treatment of a second or further recurrence of CDI, bezlotoxumab in addition to SoC is recommended for the first recurrence of CDI when fidaxomicin was used to manage the initial CDI episode, and bezlotoxumab is considered as an ancillary treatment to vancomycin for a CDI episode with high risk of recurrence when fidaxomicin is not available. Contrary to the previous guideline, in the current guideline emphasis is placed on risk for recurrence as a factor that determines treatment strategy for the individual patient, rather than the disease severity.

Evaluation of an immunochromatographic test for the detection of glutamate dehydrogenase for the diagnosis of Clostridioides (Clostridium) difficile infection in dogs

This study aimed to evaluate an immunochromatographic test used to detect glutamate dehydrogenase (GDH) for the diagnosis of Clostridium difficile infection (CDI) in dogs. Fecal samples of 119 diarrheic dogs were subjected to toxigenic culture as the "gold standard" method and to GDH detection (Ecodiagnostica, Brazil). Samples positive for toxigenic C. difficile strains and those positive in the GDH test were also subjected to A/B toxin detection using an enzyme immunoassay kit (C. difficile Tox A/B II, Techlab Inc., USA). Sensitivity, specificity, and positive and negative predictive values (PPV and NPV, respectively) were measured for GDH detection and compared with the toxigenic culture results. A total of 19 (15.9%) dogs were positive for toxigenic C. difficile. Of these, 10 (52.6%) dogs were positive for A/B toxins using the enzyme immunoassay kit and 18 (15.2%) were positive in the GDH test, leading to a sensitivity and NPV of 89.4% and 97.9%, respectively. Three animals, two of which were colonized with non-toxigenic strains, were positive for GDH, though not confirmed with CDI, resulting in a high specificity (97%) and PPV (85%). The results suggest that the lateral flow test for GDH detection could be a useful method for diagnosing CDI in dogs, similar to that previously described for humans and other animal species.

Pediatric Clostridioides difficile Infection: Diagnosis and Diagnostic Stewardship

Although the pathogenesis of Clostridioides difficile infection (CDI) is complex and incompletely understood, it is believed that the elaboration of C. difficile toxins is necessary for disease. There are a variety of tests available for the detection of both the C. difficile organism and its toxins; however, each has limitations and the best application of these tests to the diagnosis of CDI in children remains uncertain. Nucleic acid amplification tests are unable to reliably discriminate between CDI and C. difficile colonization, while commercially available enzyme immunoassays for toxin detection lack sensitivity. An understanding of preanalytic factors, relevant patient features, and test performance characteristics is essential to the accurate diagnosis of CDI in children. Specific diagnostic stewardship strategies can also increase the likelihood that positive tests reflect disease rather than colonization. Ultimately, CDI remains a clinical diagnosis and clinical judgment is essential when interpreting test results, regardless of the methods used.

So Many Diagnostic Tests, So Little Time: Review and Preview of Candida auris Testing in Clinical and Public Health Laboratories

The recognition of a new yeast, Candida auris, in 2009 in East Asia, and its rapid global spread, was a reminder of the threats posed by multidrug-resistant fungal pathogens. C. auris had likely remained unrecognized for a long time as accurate tests were not available. The laboratory community responded to the C. auris challenge by publishing 35 new or revised diagnostic methods between 2014 and early 2021. The commercial sector also modified existing diagnostic devices. These C. auris diagnostic tests run the gamut from traditional culture-based differential and selective media, biochemical assimilations, and rapid protein profiles, as well as culture-independent DNA-based diagnostics. We provide an overview of these developments, especially the tests with validation data that were subsequently adopted for common use. We share a workflow developed in our laboratory to process over 37,000 C. auris surveillance samples and 5,000 C. auris isolates from the outbreak in the New York metropolitan area. Our preview covers new devices and diagnostic approaches on the horizon based on microfluidics, optics, and nanotechnology. Frontline laboratories need rapid, cheap, stable, and easy-to-implement tests to improve C. auris diagnosis, surveillance, patient isolation, admission screening, and environmental control. Among the urgent needs is a lateral flow assay or similar device for presumptive C. auris identification. All laboratories will benefit from devices that allow rapid antifungal susceptibility testing, including detection of mutations conferring drug resistance. Hopefully, multiplex test panels are on the horizon for synergy of C. auris testing with ongoing surveillance of other healthcare-associated infections. C. auris genome analysis has a proven role for outbreak investigations, and diagnostic laboratories need quick access to regional and national genome analysis networks.

Clostridium Difficile and COVID-19: General Data, Ribotype, Clinical Form, Treatment-Our Experience from the Largest Infectious Diseases Hospital in Western Romania

Background and Objectives: In Coronavirus Disease 2019 (COVID-19), which is caused by the infection with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the clinical manifestations are primarily related to the pulmonary system. Under 10% of cases also develop gastrointestinal events such as diarrhea, nausea, vomiting and abdominal pain. Materials and Methods: We conducted an observational, retrospective study in the Infectious Diseases Clinic of "Victor Babes" Hospital, Timis County, in order to assess the incidence, outcome and risk factors for clostridium difficile infection (CDI) in COVID-19 patients. Results: Out of 2065 COVID-19 cases, hospitalized between 1st September 2020 and 30th April 2021, 40 cases of CDI were identified with 32 cases of hospital-onset of CDI and eight cases of community-onset and healthcare-associated CDI. By randomization, polymerase chain reaction ribotyping of Clostridium Difficile was performed in six cases. All the randomized cases tested positive for ribotype 027. The percentage of cases recovered with complications at discharge was higher among COVID-19 patients and CDI (p = 0.001). The in-hospital stay, 36 days versus 28 days, was longer among COVID-19 patients and CDI (p = 0.01). The presence of previous hospitalization (p = 0.004) and administration of antibiotics during the hospital stay, increased the risk of CDI among COVID-19 patients. The mean adjusted CCI at admission was lower among controls (p = 0.01). In two cases, exitus was strictly CDI-related, with one case positive for 027 ribotype. Conclusions: CDI has complicated the outcome of COVID-19 patients, especially for those with comorbidities or previously exposed to the healthcare system. In the face of the COVID-19 pandemic and the widespread, extensive use of antibiotics, clinicians should remain vigilant for possible CDI and SARS-CoV-2 co-infection.

Development and clinical validation of an automated cell cytotoxicity neutralization assay for detecting Clostridioides difficile toxins in clinically relevant stools samples

OBJECTIVES

To improve the diagnostic accuracy of Clostridioides difficile infection, current U.S. and E.U. guidelines recommend multistep testing that detects the presence of C. difficile and toxin in clinically relevant stool samples to confirm active disease. An accepted gold standard to detect C. difficile toxins is the cell cytotoxicity neutralization assay (CCNA). Although highly sensitive, the traditional CCNA has limitations. One such limitation is the subjective interpretation of an analyst to recognize cytopathic effects in cultured cells exposed to a fecal sample containing toxin. To overcome this limitation, an automated CCNA was developed that replaces most human pipetting steps with robotics and incorporates CellTiterGlo® for a semi-quantitative, non-subjective measure of cell viability instead of microscopy.

METHODS

To determine sample positivity and control for non-specific cytopathic effects, two thresholds were defined and validated by evaluating the sample with/without antitoxin antisera (sample-antitoxin/sample + antitoxin): 1) a >70% cell viability threshold was validated with samples containing anti-toxin, and 2) a >1.2-fold difference cut-off where sample results above the cut-off are considered positive.

RESULTS

Assay validation demonstrated excellent accuracy, precision, and sample linearity with an LOD of 126.9 pg/mL toxin-B in stool. The positivity cut-offs were clinically validated by comparing 322 diarrheal stool sample results with those run in a predicate, microscopic readout-based CCNA. The automated CCNA demonstrated 96% sensitivity and 100% specificity compared with the predicate CCNA.

CONCLUSIONS

Overall, the automated CCNA provides a specific, sensitive, and reproducible tool to support determination of CDI epidemiology or the efficacy of interventions such as vaccines.

Prevalence of Detection of Clostridioides difficile Among Asymptomatic Children: A Systematic Review and Meta-analysis

IMPORTANCE

Detection of Clostridioides difficile has frequently been described in asymptomatic infants and children, but accurate estimates across the age spectrum are unavailable.

OBJECTIVE

To assess the prevalence of C difficile detection among asymptomatic children across the age spectrum.

DATA SOURCES

This systematic review and meta-analysis included a search of the Cochrane Central Register of Controlled Trials, MEDLINE, Embase, CINAHL, Scopus, and Web of Science for articles published from January 1, 1990, to December 31, 2020. Search terms included Clostridium difficile, Peptoclostridium difficile, Clostridioides difficile, CDF OR CDI OR c diff OR c difficile, Clostridium infections OR cd positive diarrhea OR cd positive diarrhea OR Clostridium difficile OR Peptoclostridium difficile OR pseudomembranous colitis OR pseudomembranous enterocolitis, enterocolitis, and pseudomembranous. These were combined with the following terms: bacterial colonization and colonization OR colonized OR colonizing OR epidemiology OR prevalence OR seroprevalence.

STUDY SELECTION

Studies were screened independently by 2 authors. Studies were included if they reported testing for C difficile among asymptomatic children (ie, children without diarrhea) younger than 18 years.

DATA EXTRACTION AND SYNTHESIS

Data were extracted independently and in duplicate by 2 reviewers. Preferred Reporting Items for a Systematic Review and Meta-analysis (PRISMA) guidelines were used. Data were pooled using a random-effects model.

MAIN OUTCOMES AND MEASURES

The primary outcome was prevalence of C difficile detection among asymptomatic children. Secondary outcomes included prevalence of toxigenic vs nontoxigenic strains of C difficile and prevalence of C difficile detection stratified by geographic region, income status, testing method, and year of testing.

RESULTS

A total of 95 studies with 19 186 participants were included. Rates of detection of toxigenic or nontoxigenic C difficile were greatest among infants aged 6 to 12 months (41%; 95% CI, 32%-50%) and decreased to 12% (95% CI, 7%-18%) among children aged 5 to 18 years. The prevalence of toxigenic C difficile colonization was lower, peaking at 14% (95% CI, 8%-21%) among infants aged 6 to 12 months and decreasing to 6% (95% CI, 2%-11%) among children older than 5 years. Although prevalence differed by geographic region (ie, North and South America vs Europe: β, -0.151, P = .001; North and South America vs Western Pacific: β, 0.136, P = .007), there was no difference by testing method (ie, culture vs polymerase chain reaction: β, 0.069, P = .052; culture vs enzyme immunoassay: β, -0.178, P = .051), income class (low-middle income vs high income: β, -0.144, P = .23; upper-middle vs high income: β, -0.020, P = .64), or period (before 1990 vs 2010-2020: β, -0.125, P = .19; 1990-1999 vs 2010-2020: β, -0.037, P = .42; 2000-2009 vs 2010-2020: β, -0.006, P = .86).

CONCLUSIONS AND RELEVANCE

In this systematic review and meta-analysis, C difficile colonization rates among children were greatest at 6 to 12 months of age and decreased thereafter. These estimates may provide context for interpreting C difficile test results among young children.

The future of Clostridioides difficile diagnostics

PURPOSE OF REVIEW

Although the epidemiology of Clostridioides difficile has changed, this organism continues to cause significant morbidity and mortality. This review addresses current and future approaches to the diagnosis of C. difficile disease.

RECENT FINDINGS

Over the last several years, large prospective studies have confirmed that there is no single optimal test for the diagnosis of C. difficile disease. The pendulum has swung from a focus on rapid molecular diagnosis during the years of the ribotype 027 epidemic, to a call for use of algorithmic approaches that include a test for toxin detection. In addition, diagnostic stewardship has been shown to improve test utilization, especially with molecular methods. Advances in testing include development of ultrasensitive toxin tests and an expansion of biomarkers that may be more C. difficile specific. Microbiome research may be leveraged to inform novel diagnostic approaches based on measurements of volatile and nonvolatile organic compounds in stool.

SUMMARY

As rates of C. difficile infection decline, emphasis is now on improving test utilization and a quest for improved diagnostic approaches. These approaches may involve implementation of technologies that improve toxin testing, predict patients likely to have disease and/or a severe outcome, and harnessing research on changes in the microbiome to advance metabolomics.

Evaluation of the Cepheid Xpert C. difficile diagnostic assay: an update meta-analysis

Background

Accurate and rapid diagnosis of Clostridium difficile infection (CDI) is critical for effective patient management and implementation of infection control measures to prevent transmission.

Objectives

We updated our previous meta-analysis to provide a more reliable evidence base for the clinical diagnosis of Xpert C. difficile (Xpert C. difficile) assay.

Methods

We searched PubMed, EMBASE, Cochrane Library, Chinese National Knowledge Infrastructure (CNKI), and the Chinese Biomedical Literature Database (CBM) databases to identify studies according to predetermined criteria. STATA 13.0 software was used to analyze the tests for sensitivity, specificity, positive likelihood ratio, negative likelihood ratio, diagnostic odds ratio, and area under the summary receiver operating characteristic curves (AUC). QUADAS-2 was used to assess the quality of included studies with RevMan 5.2. Heterogeneity in accuracy measures was tested with Spearman correlation coefficient and chi-square. Meta-regressions and subgroup analyses were performed to figure out the potential sources of heterogeneity. Model diagnostics were used to evaluate the veracity of the data.

Results

A total of 26 studies were included in the meta-analysis. The pooled sensitivity (95% confidence intervals [CI]) for diagnosis was 0.97(0.95–0.98), and specificity was 0.96(0.95–0.97). The AUC was 0.99 (0.98–1.00). Model diagnostics confirmed the robustness of our meta-analysis’s results. Significant heterogeneity was still observed when we pooled most of the accuracy measures of selected studies. Meta-regression and subgroup analyses showed that the sample size and type, ethnicity, and disease prevalence might be the conspicuous sources of heterogeneity.

Conclusions

The up-to-date meta-analysis showed the Xpert CD assay had good accuracy for detecting CDI. However, the diagnosis of CDI must combine clinical presentation with diagnostic testing to better answer the question of whether the patient actually has CDI in the future, and inclusion of preanalytical parameters and clinical outcomes in study design would provide a more objective evidence base.

Laboratory Diagnostic Methods for Clostridioides difficile Infection: the First Systematic Review and Meta-analysis in Korea

Background

Various methods are used for the diagnosis of Clostridioides difficile infection (CDI). We systematically analyzed and investigated the performance of current laboratory diagnostic methods for CDI.

Methods

We performed systematic review and meta-analysis of studies in PubMed, Web of Science, Cochrane Library, and KoreaMed. The following methods were evaluated glutamate dehydrogenase (GDH) enzyme immunoassays (GDH EIAs), toxin A and B detection by enzyme immunoassays (toxin AB EIAs), and nucleic acid amplification tests (NAATs) for C. difficile toxin genes. The sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of each method were calculated.

Results

Based on 39 studies, the pooled sensitivities/specificities were 92.7%/94.6%, 57.9%/97.0%, and 90.0%/95.8% for GDH EIAs, toxin AB EIAs, and NAATs, respectively, compared with those of toxigenic culture. The pooled sensitivities of automated EIAs were significantly higher than those of non-automated EIAs for both GDH and toxins A and B. The pooled sensitivity of Xpert C. difficile was significantly higher than those of other NAATs. PPVs increased as CDI prevalence increased, and NPVs were excellent when CDI prevalence was low; at CDI prevalence of 5%, PPV = 37%-65% and NPV = 97%-100%; at CDI prevalence of 50%, PPV = 92%-97% and NPV = 65%-98%.

Conclusions

Toxin AB EIAs still show unsatisfactory sensitivity, whereas GDH EIAs and NAATs show relatively high sensitivity. However, toxin AB EIAs are the most specific tests. This study may provide useful information for CDI diagnosis.

Diagnostic Methods of Clostridioides difficile Infection and Clostridioides difficile Ribotypes in Studied Sample

BACKGROUND

Clostridioides (Clostridium) difficile is the most common nosocomial pathogen and antibiotic-related diarrhea in health-care facilities. Over the last few years, there was an increase in the incidence rate of C. difficile infection cases in Slovakia. In this study, the phenotypic (toxigenicity, antimicrobial susceptibility) and genotypic (PCR ribotypes, genes for binary toxins) patterns of C. difficile isolates from patients with CDI were analyzed, from July to August 2016, taken from hospitals in the Horne Povazie region of northern Slovakia. The aim of the study was also to identify hypervirulent strains (e.g., the presence of RT027 or RT176).

METHODS

The retrospective analysis of biological samples suspected of CDI were analyzed by GDH, anaerobic culture, enzyme immunoassay on toxins A/B, multiplex "real-time" PCR and PCR capillary-based electrophoresis ribotyping, and by MALDI TOF MS.

RESULTS

C. difficile isolates (n = 44) were identified by PCR ribotyping, which revealed five different ribotypes (RT001, 011, 017, 081, 176). The presence of hypervirulent RT027 was not identified. The C. difficile isolates (RT001, 011, 081, 176) were susceptible to metronidazole and vancomycin. One isolate RT017 had reduced susceptibility to vancomycin. A statistically significant difference between the most prevalent PCR ribotypes, RT001 and RT176, regarding variables such as albumin, CRP, creatinine, the length of hospitalization (p = 0.175), and glomerular filtration (p = 0.05) was not found.

CONCLUSION

The results of PCR capillary-based electrophoresis ribotyping in the studied samples showed a high prevalence of RT176 and 001.

Clostridioides difficile infection: an emerging zoonosis?

INTRODUCTION

Clostridioides difficile (C. difficile) infection (CDI) is the most common cause of antibiotic-associated diarrhea and one of the common infections in healthcare facilities. In recent decades, there has been an emerging threat of community-acquired CDI (CA-CDI). Environmental transmission of C. difficile in the community setting has become a major concern, and animals are an important reservoir for C. difficile causing human diseases.

AREAS COVERED

In this article, the molecular epidemiology of C. difficile in animals and recent evidences of zoonotic transfer to humans are reviewed based on an electronic search in the databases of PubMed and Google Scholar.

EXPERT OPINION

C. difficile can be found in stool from diarrheal dogs and cats; therefore, household pets could be a potential source. C. difficile will threaten human health because hypervirulent C. difficile ribotype 078 strains have been found in retail chickens, pig farms, and slaughterhouses. Risk factors for fecal C. difficile carriage in animals include young age, dietary changes, and antibiotic abuse in domestic animals. With the advent of whole genome sequencing techniques, there will be more solid evidence indicating zoonotic transfer of C. difficile from animals to humans.

Descriptive Study of Gut Microbiota in Infected and Colonized Subjects by Clostridiodes difficile

Clostridiodes difficile can lead to a range of situations from the absence of symptoms (colonization) to severe diarrhea (infection). Disruption of gut microbiota provides an ideal environment for infection to occur. Comparison of gut microbiota of infected and colonized subjects could provide relevant information on susceptible groups or protectors to the development of infection, since the presence of certain genera could be related to the inhibition of transition from a state of colonization to infection. Through high-throughput sequencing of 16S rDNA gene, we performed alpha and beta diversity and composition studies on 15 infected patients (Group CDI), 15 colonized subjects (Group P), and 15 healthy controls (Group CTLR). A loss of alpha diversity and richness and a different structure have been evidenced in the CDI and P groups with respect to the CTRL group, but without significant differences between the first two. In CDI and P groups, there was a strong decrease in phylum Firmicutes and an expansion of potential pathogens. Likewise, there was a loss of inhibitory genus of C. difficile germination in infected patients that were partially conserved in colonized subjects. Therefore, infected and colonized subjects presented a gut microbiota that was completely different from that of healthy controls, although similar to each other. It is in composition where we found that colonized subjects, especially in minority genera, presented differences with respect to those infected.

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.

Cytomegalovirus-associated pseudomembranous colitis in a kidney transplant recipient

Pseudomembranous colitis (PMC) is classically associated with Clostridium difficile infection. We report a rare case of cytomegalovirus (CMV)-associated PMC in a 52-year-old female patient who had undergone kidney transplantation more than 20 years ago and was on low dose prednisolone and ciclosporin. She presented with an acute history of fever, lethargy, vomiting and diarrhoea on admission. Computed tomography of the abdomen showed extensive colitis, and colonoscopy revealed extensive pseudomembrane formation. Multiple tests for Clostridium difficile and other common microbiological causes of colitis were negative. CMV DNAemia and colonic biopsies confirmed the diagnosis of CMV colitis. The patient responded to prompt CMV treatment, as demonstrated by clinical, endoscopic, and histological response. While CMV is a common pathogen in the solid organ transplant population that is familiar to most transplant physicians, it may present atypically as PMC. Here, we review the literature on CMV-associated PMC and its relevance to solid organ transplant recipients. To our knowledge, this is the first reported case of CMV-associated PMC in a kidney transplant recipient.

Evaluation of loop-mediated isothermal amplification assay for detection of Clostridioides difficile infection: A prospective diagnostic performance study

A novel Loop-mediated isothermal amplification (LAMP) assay, HiberGene's CD was evaluated with 82 unformed stools from patients suspected of C. difficile infection (CDI). Compared to glutamate dehydrogenase (GDH) toxins A/B test (C.diff Quik Chek®), HiberGene's LAMP showed 100% of sensitivity and 95,8% of specificity; and compared to FilmArray™ GI panel ® (BioFire), a sensitivity of 81,2% and a specificity of 100%, with 96.38% of agreement.

Evaluation of Clostridium difficile Infection with PET/CT Imaging in a Mouse Model

PURPOSE

Existing clinical or microbiological scores are not sensitive enough to obtain prompt identification of patients at risk of complicated Clostridium difficile infection (CDI). Our aim was to use a CDI animal model to evaluate 2-deoxy-2-[¹⁸F]fluoro-D-glucose positron emission tomography ([¹⁸F]FDG-PET) as a marker of severe course of infection.

PROCEDURES

CDI was induced with cefoperazone for 10 days followed by clindamycin 1 day before C. difficile inoculation. Mice were divided into wild type (n = 6), antibiotic without infection (AC n = 4), h001-infected (n = 5, ribotype 001), and h027-infected (n = 5, ribotype 027). Two days after inoculation, [¹⁸F]FDG-PET was acquired. Weight, general animal condition, and survival were monitored daily for 9 days.

RESULTS

h001 group showed symptoms for 4 days with 0 % mortality and a similar colon uptake than control animals (h001 0.52 ± 0.20, WT 0.42 ± 0.07, and AC 0.36 ± 0.06). The h027 group showed symptoms up to 7 days, with 66.7 % of mortality 4 days after infection, and significantly higher colon uptake (0.93 ± 0.38, p < 0.05). Clinical score was associated to colon and cecum uptake (rho = 0.78, p = 0.0001) (rho = 0.73, p = 0.0003).

CONCLUSION

High toxin producer ribotype 027 induced more severe CDI infections, correlating with higher colon and cecum [¹⁸F]FDG uptake. Colon uptake may purportedly serve as early predictor of CDI severity.

ACG Clinical Guidelines: Prevention, Diagnosis, and Treatment of Clostridioides difficile Infections

Clostridioides difficile infection occurs when the bacterium produces toxin that causes diarrhea and inflammation of the colon. These guidelines indicate the preferred approach to the management of adults with C. difficile infection and represent the official practice recommendations of the American College of Gastroenterology. The scientific evidence for these guidelines was evaluated using the Grading of Recommendations Assessment, Development, and Evaluation process. In instances where the evidence was not appropriate for Grading of Recommendations Assessment, Development, and Evaluation but there was consensus of significant clinical merit, key concept statements were developed using expert consensus. These guidelines are meant to be broadly applicable and should be viewed as the preferred, but not the only, approach to clinical scenarios.

Detection of Free Toxin B in the Stool of Asymptomatic Clostridioides difficile Carriers by the Cell Cytotoxicity Neutralization Assay

Cell cytotoxicity neutralization assay (CCNA) is considered to be a gold standard to diagnose Clostridioides difficile infections. We performed CCNA on 77 consecutive admission screening rectal swabs from asymptomatic toxigenic C. difficile carriers. Thirty-nine percent of specimens from asymptomatic carriers were positive. Thus, CCNA specificity may be lower than previously thought.

Molecular epidemiology and antimicrobial resistance of Clostridioides difficile in Germany, 2014-2019

Clostridioides difficile is a Gram positive spore-forming rod and mainly responsible for nosocomial diarrhea in developed nations. Molecular and antimicrobial surveillance is important for monitoring the strain composition including genotypes of high epidemiological importance such as ribotype 027 (RT027) and corresponding resistance patterns. 1535 isolates obtained from samples sent between 2014 and 2019 to the German National Reference Center (NRC) for diagnostic reasons (NRC strain set), and 1143 isolates from a Tertiary Care University Center in Saarland, Germany (non-NRC strain set), were evaluated using antibiotic susceptibility testing and ribotyping. In the NRC strain set, RT027 overtook RT001, the main RT found in the preceding studies, and dominated with 36.2%, followed by RT001 (13.3%), and RT014 (8.5%). Of note, since 2016 a constant decrease of RT027 could be noticed. In the non-NRC strain set a large strain diversity was present with RT014 (18%) and RT001 (8.9%) being most prevalent. In NRC samples, resistance towards metronidazole, vancomycin, moxifloxacin, clarithromycin and rifampicin was 2.7%, 0%, 57.1%, 53.2% and 19.2%, respectively. Metronidazole resistance was almost exclusively found in RT027 isolates. Rifampicin resistance was also observed predominantly in isolates of RT027, constituting an almost four-fold increase, when compared to preceeding studies in this region. In conclusion these data demonstrate that RT027 is a driver for rifampicin and metronidazole resistance, underlining the importance of continuous surveillance efforts.

Incidence and predictive biomarkers of Clostridioides difficile infection in hospitalized patients receiving broad-spectrum antibiotics

Trial enrichment using gut microbiota derived biomarkers by high-risk individuals can improve the feasibility of randomized controlled trials for prevention of Clostridioides difficile infection (CDI). Here, we report in a prospective observational cohort study the incidence of CDI and assess potential clinical characteristics and biomarkers to predict CDI in 1,007 patients ≥ 50 years receiving newly initiated antibiotic treatment with penicillins plus a beta-lactamase inhibitor, 3rd/4th generation cephalosporins, carbapenems, fluoroquinolones or clindamycin from 34 European hospitals. The estimated 90-day cumulative incidences of a first CDI episode is 1.9% (95% CI 1.1-3.0). Carbapenem treatment (Hazard Ratio (95% CI): 5.3 (1.7-16.6)), toxigenic C. difficile rectal carriage (10.3 (3.2-33.1)), high intestinal abundance of Enterococcus spp. relative to Ruminococcus spp. (5.4 (2.1-18.7)), and low Shannon alpha diversity index as determined by 16 S rRNA gene profiling (9.7 (3.2-29.7)), but not normalized urinary 3-indoxyl sulfate levels, predicts an increased CDI risk.

Microbiota-based markers predictive of development of Clostridioides difficile infection

Antibiotic-induced modulation of the intestinal microbiota can lead to Clostridioides difficile infection (CDI), which is associated with considerable morbidity, mortality, and healthcare-costs globally. Therefore, identification of markers predictive of CDI could substantially contribute to guiding therapy and decreasing the infection burden. Here, we analyze the intestinal microbiota of hospitalized patients at increased CDI risk in a prospective, 90-day cohort-study before and after antibiotic treatment and at diarrhea onset. We show that patients developing CDI already exhibit significantly lower diversity before antibiotic treatment and a distinct microbiota enriched in Enterococcus and depleted of Ruminococcus, Blautia, Prevotella and Bifidobacterium compared to non-CDI patients. We find that antibiotic treatment-induced dysbiosis is class-specific with beta-lactams further increasing enterococcal abundance. Our findings, validated in an independent prospective patient cohort developing CDI, can be exploited to enrich for high-risk patients in prospective clinical trials, and to develop predictive microbiota-based diagnostics for management of patients at risk for CDI.

Usefulness of Fecal Calprotectin in the Management of Patients with Toxigenic Clostridioides difficile

The availability of highly sensitive molecular tests for the detection of Clostridioides difficile in feces leads to overtreatment of patients who are probably only colonized. In this prospective study, the usefulness of fecal calprotectin (fCP) is evaluated in a cohort of patients with detection of toxigenic C. difficile in feces. Patients were classified by an infectious diseases consultant blinded to fCP results into three groups-group I, presumed Clostridioides difficile infection (CDI); group II, doubtful but treated CDI; and group III, presumed C. difficile colonization or self-limited CDI not needing treatment. One hundred and thirty-four patients were included. The median fCP concentrations were 410 (138-815) μg/g in group I, 188 (57-524) μg/g in group II, and 51 (26-97) μg/g in group III (26 cases); p < 0.05 for all comparisons. In forty-five out of 134 cases (33.5%), the fCP concentrations were below 100 µg/g. In conclusion, fCP is low in most patients who do not need treatment against C. difficile, and should be investigated as a potentially useful test in the management of patients with detected toxigenic C. difficile.

Predictive factors, outcomes, and molecular epidemiology of Clostridioides difficile diarrhea in Brazilian hospitals

Little is known about the role of lineage of strains of Clostridioides difficile (CD) on the clinical presentation of CD infection (CDI) in Latin America, especially regarding the treatment response. We conducted a multicenter, prospective study to investigate the predictive factors and treatment outcomes of CDI in hospitalized patients and to performed phenotypical and molecular characterization of CD strains. A total of 361 diarrheic patients at 5 hospitals from different regions of the country were enrolled. All stool samples were tested for glutamate dehydrogenase (GDH), toxins A and B, and toxin genes using a nucleic acid amplification test (NAAT). Specimens were cultured and susceptibility profile and whole-genome sequencing (WGS) were performed. CDI positivity was 15% (56/377). Predictive factors for CDI were prior use of meropenem (OR 4.09, 95% CI 2.097-7.095; p<0.001), mucus in stools (OR 3.29; 95% CI 1.406-7.722; p=0.006) and neutrophil left-shift with >20% of bands (OR 3.77; 95% IC 1.280-11.120; p=0.016). Overall mortality was 19%, with no deaths attributed to CDI. Oral metronidazole was used in 74% of cases, with 85% of cure and 14% of recurrence. A total of 35 CD isolates were recovered, all of them susceptible to metronidazole and vancomycin. The WGS revealed 17 different STs, six of which were novel. ST42 was the most common ST and hypervirulent strains were not found. Severe CDI were caused by ST42, ST5, ST8, ST48, ST33 and a novel ST667. The ermB gene was more frequently found in isolates of ST42 (p=0.004).

Clostridium difficile: Diagnosis and the Consequence of Over Diagnosis

Clostridium difficile infection (CDI) is a leading cause of healthcare-associated infections, accounting for significant disease burden and mortality. The clinical spectrum of C. difficile ranges from asymptomatic colonization to toxic megacolon and fulminant colitis. CDI is characterized by new onset of ≥ 3 unformed stools in 24 h and is confirmed by laboratory test for the presence of toxigenic C. difficile. Currently, laboratory tests to diagnose CDI include toxigenic culture, glutamate dehydrogenase (GDH), nucleic acid amplification test (NAAT), and toxins A/B enzyme immunoassay (EIA). The sensitivities of these tests are variable with toxin EIA ranging from 53 to 60% and with NAAT at about 95%. Overall, the specificity is > 90% for these methods. However, the positive predictive value (PPV) depends on the disease prevalence with lower CDI rates associated with lower PPVs.

Notably, the widespread use of the highly sensitive NAAT and its relatively lower clinical specificity have led to overdiagnosis of C. difficile by identifying carriers when NAAT is used as the sole diagnostic method. Overdiagnosis of C. difficile has resulted in unwarranted treatment, possibly attributing to resistance to metronidazole and vancomycin, increased risk for overgrowth of vancomycin-resistant enterococci strains in stool specimens, and increased hospitalization thereby impacting patient safety and healthcare costs.

Strategies to optimize the clinical sensitivity and specificity of current laboratory tests are critical to differentiate the clinical CDI from colonization. To achieve high diagnostic yield, if preagreed institutional criteria for stool submission are not used, a multistep approach to CDI diagnosis is recommended, such as either GDH or NAAT followed by toxins A/B EIA in conjunction with laboratory stewardship by evaluating C. difficile test orders for appropriateness and providing feedback. Furthermore, antimicrobial stewardship, along with provider education on appropriate testing for C. difficile, is vital to differentiate CDI from colonization.

Advances and required improvements in methods to diagnosing Clostridioides difficile infections in the healthcare setting

INTRODUCTION

Clostrididioides difficile is associated with adverse clinical outcomes and increased morbidity, mortality, length of hospital stay, and health-care costs.Areas Covered: We searched relevant papers in PubMed for the last 10 years. In major papers, we scanned the bibliographies to ensure that important articles were included. This review addresses the evolving epidemiology of Clostridioides difficile infection (CDI) and discusses novel methods/approaches for improving the diagnosis of this important disease.

EXPERT OPINION

No single diagnostic test to date has demonstrated optimum sensitivity and specificity for detection of CDI. Many institutions have developed multi-step algorithms consistent with guidelines established by various professional societies. Some institutions have successfully tried to improve the pretest probability of molecular assays by implementing appropriate sample rejection criteria and establishing best practice alerts at the time of electronic order entry. Others have established PCR cycle threshold cutoffs to attempt to differentiate symptomatic patients from asymptomatic carriers or to make predictions about severity of disease with variable success. As research advances our understanding of C. difficile pathogenesis and pathophysiology, more information on CDI specific biomarkers is emerging. Finally, assessments of the microbiome and metabolome may expand the diagnostic armamentarium with advances in mass spectrometry and sequencing technologies.

Paper-based multiplex analytical device for simultaneous detection of Clostridioides difficile toxins and glutamate dehydrogenase

We report a new paper-based multiplex analytical device (mPAD) for simultaneous screening of three analytes (glutamate dehydrogenase, toxin A, and toxin B) known as biomarkers for Clostridioides difficile infection (CDI). To overcome the limitation of common rapid assays (e.g. lateral flow immunochromatographic and enzyme immunoassays) in terms of multiplexing, sensitivity, simplicity, and ease-of-use, the mPAD is constructed with a three dimensional (3D) configuration of paper components with a multi-channel design. Multiple fluidic paths developed with wax-patterned paper allow the simultaneous detection of glutamate dehydrogenase, toxin A, and toxin B without any cross-reactivity. The 3D fluidic network on the mPAD facilitates a self-operating test procedure for the mixing and addition of amplification reagents with a one-step sliding operation. The results of the multiplex CDI assay can be easily interpreted by the naked eye within 10 min, and are visually intensified over time resulting in up to 3-fold signal amplification. Our device exhibited remarkable analytical performances for the simultaneous detection of three CDI biomarkers, providing a sensitivity of 97%, specificity of 88%, accuracy of 95%, and limits of detection for glutamate dehydrogenase, toxin A, and toxin B of 0.16 ng mL^-1, 0.09 ng mL^-1, and 0.03 ng mL^-1, respectively. These results indicate the high applicability and feasibility of mPAD for multiplex testing for CDI with the advantages of being simple, sensitive, inexpensive, user-friendly, and equipment-free.

Trends in Clostridioides difficile diagnosis before and after a change in testing algorithm

Clostridioides difficile (Clostridium difficile) (CD) infection remains a challenging diagnosis in hospitalized patients given the myriad of testing procedures and array of alternative causes for diarrhea. We identified 100 consecutive inpatients with positive CD testing in a single tertiary center before and after changing from nucleic acid amplification testing (NAAT) alone to a two-step algorithm involving Glutamate Dehydrogenase enzyme immunoassays (GDHEIA) followed by an enzyme immunoassay for CD toxins (EIA). Detailed clinical information was obtained retrospectively to assess for risk factors, clinical features, and treatment outcomes to correlate test results with clinical cases. We demonstrate that using a 2-step testing algorithm identifies patients with a consistent clinical illness for CD disease significantly more often than nucleic acid amplification testing alone without an increase in cases of severe CD disease. Our data suggest that NAAT alone results in an increase in unnecessary treatment of CD colonization.

Significance of a polymerase chain reaction method in the detection of Clostridioides difficile

OBJECTIVE

Clostridioides difficile (CD) is the most common cause of nosocomial diarrhea. Detection of CD toxin in patients' faecal samples is the traditional rapid method for the diagnosis of CD infection. Various testing algorithms have been proposed: an initial screening test using a rapid test, and a confirmatory test (cytotoxicity neutralization assay, toxigenic culture, nucleic acid amplification test) for discordant results. The aim of this study was to evaluate the effectiveness of a two-step algorithm using an immunochromatographic test followed of a polymerase chain reaction (PCR).

METHODS

The specimens have been tested according to the following schedule: 1) Step one: All samples were tested for detection of glutamate dehydrogenase antigen (GDH) and toxin A/B using the C. diff QUIK CHEK Complete test. All GDH and toxins positive results were considered CD positives; 2) Step two: When the results were discrepant (only GDH+ or toxins+), the samples were confirmed using the PCR test BD MAX Cdiff. All PCR positive results were considered CD positives.

RESULTS

A total of 2,138 specimens were initially tested. 139 were positive for GDH and toxins. 160 discrepant results (148 GDH+ and 12 toxins+) were tested by PCR, 117 were positive (107/148 GDH+ and 10/12 toxins+).

CONCLUSIONS

The implementation of a PCR method showed an increase de 117 positive results (73.1% of discrepant). Considering the sensitivity of C.diff QUIK CHEK (instructions of manufacturer), the GDH discrepant results may be false negatives, y the samples PCR and toxins positives may be real positives results.

MALDI-TOF MS: An alternative approach for ribotyping Clostridioides difficile isolates in Brazil

Clostridioides difficile is an important organism causing healthcare-associated infections. It has been documented that specific strains caused multiple outbreaks globally, and patients infected with those strains are more likely to develop severe C. difficile infection (CDI). With the appearance of a variant strain, BI/NAP1 ribotype 027, responsible for several outbreaks and high mortality rates worldwide, the epidemiology of the CDI changed drastically in the United States, Europe, and some Latin American countries. Although the epidemic strain 027 was not yet detected in Brazil, there are ribotypes exclusively found in the country, such as, 131, 132, 133, 135, 142 and 143, which are responsible for outbreaks in Brazilian hospitals and nursing homes. Although PCR-ribotyping is the most used method in epidemiology studies of C. difficile, it is not available in Brazil. This study aimed to develop and validate an in-house database for detecting C. difficile ribotypes, usually involved in CDI in Brazilian hospitals, by using MALDI-TOF MS. A database with 19 different ribotypes, 13 with worldwide circulation and 6 Brazilian-restricted, was created based on 27 spectra readings of each ribotype. After BioNumerics analysis, neighbor-joining trees revealed that spectra were distributed in clusters according to ribotypes, showing that MALDI-TOF MS could discriminate all 19 ribotypes. Moreover, each ribotype showed a different profile with 42 biomarkers detected in total. Based on their intensity and occurrence, 13 biomarkers were chosen to compose ribotype-specific profiles, and in silico analysis showed that most of these biomarkers were uncharacterized proteins or well-conserved peptides, such as ribosomal proteins. A double-blind assessment using the 13 biomarkers correctly assigned the ribotype in 73% of the spectra analyzed, with 94%-100% of correct hits for 027 and for Brazilian ribotypes. Although further analyses are required, our results show that MALDI-TOF MS might be a reliable, fast and feasible alternative for epidemiological surveillance of C. difficile in Brazil.

Performance Comparison of a Novel Rapid Stand-alone Molecular Test and a 2-Step Diagnostic Algorithm for Clostridioides difficile Detection in Children

BACKGROUND

We aimed to evaluate diagnostic performance of the cobas® Liat® Cdiff test, a novel single-step automated polymerase chain reaction (PCR) assay for rapid diagnosis of toxigenic Clostridioides difficile infection (CDI) in stool samples from children with clinical symptoms of CDI.

METHODS

Assessment of cobas Liat Cdiff diagnostic yield, time of analytical process and agreement of results with those of a 2-step diagnostic algorithm. The sequential algorithm combined an enzyme immunoassay (EIA) targeting antigen glutamate dehydrogenase (GDH), enterotoxin-A and cytotoxin-B, and a confirmatory PCR in EIA GDH-positive and toxin-negative samples. Fresh stool samples were collected prospectively from patients 2-18 years of age that were attended in Hospital Sant Joan de Deu (Barcelona, Spain) during December 2018-August 2019.

RESULTS

A total of 122 specimens were collected from 91 children (mean age, 8 years; 69.7% male). cobas Liat Cdiff identified 24 (19.7%) positive samples. EIA yielded 97 (79.5%) GDH- and toxin-negative results, 11 (9.0%) GDH- and toxin-positive results, and 14 (11.5%) GDH-positive and toxin-negative results, of which 11 (9.0%) were positive for the toxin by the confirmatory PCR. Overall, GDH- and toxin-positive samples detected by the sequential algorithm were 22 (18.0%). Comparatively, the new test reduced time of the analytical process significantly (20 vs. 35.4 minutes, P < 0.001).

CONCLUSION

Use of cobas Liat Cdiff showed similar detection yield compared with a 2-step diagnostic algorithm that combined an EIA and a confirmatory PCR while decreasing the time of the analytical process markedly in stool samples from children suspected of CDI.

Simultaneous detection and ribotyping of Clostridioides difficile, and toxin gene detection directly on fecal samples

Background

Clostridioides difficile is the most common cause of nosocomial diarrhea. Ribotyping of cultured strains by a PCR-based test is used to study potential transmission between patients. We aimed to develop a rapid test that can be applied directly on fecal samples for simultaneous detection and ribotyping of C. difficile, as well as detection of toxin genes.

Methods

We developed a highly specific and sensitive primer set for simultaneous detection and ribotyping of C. difficile directly on total fecal DNA. Toxin genes were detected with primers adapted from Persson et al. (Clin Microbiol Infect 14(11):1057–1064). Our study set comprised 130 fecal samples: 65 samples with positive qPCR for C. difficile toxin A/B genes and 65 C. difficile qPCR negative samples. PCR products were analyzed by capillary gel electrophoresis.

Results

Ribosomal DNA fragment peak profiles and toxin genes were detected in all 65 C. difficile positive fecal samples and in none of the 65 C. difficile negative samples. The 65 samples were assigned to 27 ribotypes by the Dutch reference laboratory. Our peak profiles corresponded to these ribotypes, except for two samples. During a C. difficile outbreak, patients were correctly allocated to the outbreak-cluster based on the results of direct fecal ribotyping, before C. difficile isolates were cultured and conventionally typed.

Conclusion

C. difficile ribotyping directly on fecal DNA is feasible, with sensitivity and specificity comparable to that of diagnostic toxin gene qPCR and with ribotype assignment similar to that obtained by conventional typing on DNA from cultured isolates. This supports simultaneous diagnosis and typing to recognize an outbreak.