False Negative Results in Clostridium difficile Testing

Informing estimates of probability of Clostridioides difficile infection for testing and treatment: expert consensus from a modified-Delphi procedure

Background

Clostridioides difficile infection (CDI) may be misdiagnosed if testing is performed in the absence of signs or symptoms of disease. This study sought to support appropriate testing by estimating the impact of signs, symptoms, and healthcare exposures on pre-test likelihood of CDI.

Methods

A panel of fifteen experts in infectious diseases participated in a modified UCLA/RAND Delphi study to estimate likelihood of CDI. Consensus, defined as agreement by >70% of panelists, was assessed via a REDCap survey. Items without consensus were discussed in a virtual meeting followed by a second survey.

Results

All fifteen panelists completed both surveys (100% response rate). In the initial survey, consensus was present on 6 of 15 (40%) items related to risk of CDI. After panel discussion and clarification of questions, consensus (>70% agreement) was reached on all remaining items in the second survey. Antibiotics were identified as the primary risk factor for CDI and grouped into three categories: high-risk (likelihood ratio [LR] 7, 93% agreement among panelists in first survey), low-risk (LR 3, 87% agreement in first survey), and minimal-risk (LR 1, 71% agreement in first survey). Other major factors included new or unexplained severe diarrhea (e.g., ≥ 10 liquid bowel movements per day; LR 5, 100% agreement in second survey) and severe immunosuppression (LR 5, 87% agreement in second survey).

Conclusion

Infectious disease experts concurred on the importance of signs, symptoms, and healthcare exposures for diagnosing CDI. The resulting risk estimates can be used by clinicians to optimize CDI testing and treatment.

Impact of Clostridium difficile Infection Versus Colonization on Postoperative Outcomes After Oncological Colorectal Surgery: An Observational Single-Center Study With Propensity Score Analysis

BACKGROUND

There is limited research available concerning the risk anastomotic leakage in the context of Clostridium difficile infection (CDI). Herein, we aim to elucidate the correlation between CDI, encompassing both preoperative asymptomatic C. difficile carriers (CDC) and postoperative hospital acquired C. difficile infections (HA-CDI), and the occurrence of anastomotic leakage in patients undergoing oncological colorectal surgery.

METHODS

This is an observational, single-center study. Data were sourced from surgical logs between 2018 and 2023, via the hospital's electronic system. Patients were split into three subgroups: CDC, HA-CDI, and control group (CG). Groups were compared in terms of patient characteristics, morbidity, and mortality via Fisher's exact test and Kruskal-Wallis test. One-to-one propensity score matching was performed to reduce selection bias.

RESULTS

A total of 522 patients were analyzed, split into three subgroups: CDC, n = 35; HA-CDI, n = 27; CG, n = 460. One-to-one propensity score matching reduced the CG to 62 patients. Patients in the HA-CDI group had higher rates of overall morbidity (p < 0.0001), higher rates of anastomotic leaks (p = 0.002), more surgical site infections (SSI) (p = 0.001), and a longer length of stay (26 vs. 11.2 vs. 9.3 days, p < 0.001), while patients in the CDC group had comparable rates of complications with the CG.

CONCLUSION

HA-CDI is associated with a higher risk of anastomotic leak after oncological colorectal surgery, while asymptomatic CDC do not have higher morbidity and may be operated electively, under standard CD treatment.

Positive pathogens in stool could predict the clinical outcomes of sepsis-associated acute kidney injury in critical ill patient

In this study, we sought to evaluate the influence of positive pathogens in stool (PPS) on clinical outcomes in critical ill patients with Sepsis-associated acute kidney injury (S-AKI) from intensive care unit. Our sample consisted of 7338 patients, of whom 752 (10.25%) had PPS. We found that the presence of Clostridium difficile (C. difficile) and protists in stool samples was correlated with survival during hospitalization, as well as 30-day and 90-day survival. Interestingly, there was no significant difference in overall survival and 30-day in-hospital survival between the PPS group and the negative pathogens in stool (NPS) control group. However, the cumulative incidence of 90-day infection-related mortality was significantly higher in the PPS group (53 vs. 48%, P = 0.022), particularly in patients with C. difficile in their stool specimens. After adjusting for propensity scores, the results also have statistical significance. These findings suggest that PPS may affect the 90-days survival outcomes of S-AKI, particularly in patients with C. difficile and protists in their stool samples. Further research is warranted to further explore these associations.

A Rare Case of Polymerase Chain Reaction-Negative Severe Clostridioides difficile Infection

Accurately diagnosing Clostridioides difficile infection (CDI) is crucial for effective patient management. A misdiagnosis poses risks to patients, leads to treatment delays, and contributes to infection transmission in healthcare settings. While using polymerase chain reaction (PCR) to amplify the toxin B gene is a sensitive method for detecting toxigenic C. difficile, there is still a risk of false-negative results. These inaccuracies could have significant consequences for diagnosing and treating CDI, emphasizing the need for careful consideration and other diagnostic approaches. This case report highlights a patient with severe CDI who had negative PCR and toxin and a biopsy showing pseudomembranous colitis on further testing due to persistence and worsening of symptoms. In the diagnosis of C. difficile infection, healthcare providers should consider clinical symptoms, although diarrhea, which is a major sign of CDI, can be due to other causes. Even in the presence of negative PCR results, if a patient displays symptoms consistent with C. difficile-associated disease, healthcare providers may still contemplate treatment.

A Review on Clostridioides Difficile Testing and How to Approach Patients With Multiple Negative Tests: A Case Report

Clostridioides difficile (C. difficile) is an important nosocomial infection that is commonly associated with antibiotic use with pseudomembranous colitis being present in only 13% of cases. Disease severity ranges from asymptomatic carriers to severe complicated disease, based on clinical and laboratory findings. There is no single rapid FDA-approved test to diagnose C. difficile infections (CDI) and diagnosis usually requires a multi-step diagnostic approach. C. difficile testing usually begins with the C. difficile toxin and glutamate dehydrogenase antigen screen (GDH). If testing is negative for either, then nucleic acid amplification testing (NAAT) is done to confirm the diagnosis. Endoscopic evaluation may be required in rare instances when there is a high clinical suspicion of disease with negative testing. Here, we present an interesting case of a patient with multiple negative C. difficile toxin and GDH tests. Given the high index of clinical suspicion of CDI, the patient underwent a colonoscopy which revealed diffuse pseudomembranous colitis. The patient was then appropriately treated with oral vancomycin. We aim to shed light on the different testing modalities available to clinicians and the indications for doing a colonoscopy to delineate between false positive testing and active CDI.

SEE the DIFFerence: Reducing unnecessary C. difficile orders through clinical decision support in a large, urban safety-net system

BACKGROUND

Clostridioides difficile (C. difficile) is a hospital-acquired infection. Overtesting for C. difficile leads to false positive results due to a high rate of asymptomatic colonization, resulting in unnecessary and harmful treatment for patients.

METHODS

This was a quality improvement initiative to decrease the rate of inappropriate C. difficile testing across 11 hospitals in an urban, safety-net setting. Three best practice advisories were created, alerting providers of recent laxative administration within 48 hours, a recent positive test within 14 days, and a recent negative test within 7 days. The outcome measures were the number of C. difficile tests per 1,000 patient days, as well as the rate of hospital onset C. difficile infection was compared pre- and post-intervention. The process measures included the rate of removal of the C. difficile test from the best practice advisory, as well as the subsequent 24-hour re-order rate.

RESULTS

The number of C. difficile tests decreased by 27.3% from 1.1 per 1,000 patient days preintervention (May 25, 2020-May 24, 2021) to 0.8 per 1,000 patient days postintervention, (May 25, 2021-March 25, 2022), P < .001. When stratified by hospital, changes in testing ranged from an increase of 12.5% to a decrease of 60%. Analysis among provider type showed higher behavior change among attendings than compared to trainees or advanced practice providers. There was a 12.1%, nonsignificant decrease in C. difficile rates from preintervention, 0.33 per 1,000 patient days compared to postintervention, 0.29 per 1,000 patient days, P=.32.

CONCLUSIONS

Using only an electronic health record intervention, we successfully decreased C. difficile orders after 72 hours of admission in a large, safety-net system. Variation existed among hospitals and by provider type.

Low-Toxin Clostridioides difficile RT027 Strains Exhibit Robust Virulence

Clostridioides difficile is a leading cause of healthcare-associated infections worldwide. Currently, there is a lack of consensus for an optimal diagnostic method for C. difficile infection (CDI). Multi-step diagnostic algorithms use enzyme immunosorbent analysis (EIA)-based detection of C. difficile toxins TcdA/TcdB in stool, premised on the rationale that EIA toxin-negative (Tox⁻) patients have less severe disease and shorter diarrhoea duration. The aim of this study was to characterize toxigenic (i.e. tcdA/tcdB-positive) C. difficile strains isolated from diarrheic patient stool with an EIA Tox⁻ (i.e. “discrepant”) CDI diagnostic test result. Recovered strains were DNA fingerprinted (ribotyped), subjected to multiple toxin, genome and proteome evaluations, and assessed for virulence. Overall, of 1243 C. difficile-positive patient stool specimens from Southern Arizona hospitals, 31% were discrepant. For RT027 (the most prevalent ribotype)-containing specimens, 34% were discrepant; the corresponding RT027 isolates were cytotoxic to cultured fibroblasts, but their total toxin levels were comparable to, or lower than, the historic low-toxin-producing C. difficile strain CD630. Nevertheless, these low-toxin RT027 strains (LT-027) exhibited similar lethality to a clade-matched high-toxin RT027 strain in Golden Syrian hamsters, and heightened colonization and persistence in mice. Genomics and proteomics analyses of LT-027 strains identified unique genes and altered protein abundances, respectively, relative to high-toxin RT027 strains. Collectively, our data highlight the robust virulence of LT-027 C. difficile, provide a strong argument for reconsidering the clinical significance of a Tox⁻ EIA result, and underscore the potential limitations of current diagnostic protocols.

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.

Whole-genome sequencing of clinical Clostridioides difficile isolates reveals molecular epidemiology and discrepancies with conventional laboratory diagnostic testing

BACKGROUND

The high clinical burden of Clostridioides difficile infections merits rapid and sensitive identification of affected individuals. However, effective diagnosis remains challenging. Current best practice guidelines recommend molecular and/or direct toxin detection-based screening for symptomatic individuals, but previous work has called into question the concordance and performance of extant clinical assays.

AIM

To better correlate the genomic and phenotypic properties of clinical C. difficile isolates with laboratory testing outcomes in both C. difficile-infected patients and asymptomatic carriers.

METHODS

Whole-genome sequencing of clinical C. difficile isolates collected from an inpatient population at a single healthcare institution was performed, enabling examination of their molecular epidemiology and toxigenic gene content. Genomic findings were compared with clinical testing outcomes, identifying multiple diagnostic discrepancies.

FINDINGS

Toxigenic culture, considered a 'reference standard', provided perfect sensitivity and specificity in predicting toxigenic gene content, whereas reduced performance was observed for Simplexa C. difficile Direct Assay (100% specificity, 88% sensitivity), Gene Xpert CD/Epi Assay (86% specificity, 83% sensitivity), and Quick Check Complete Tox A/B (100% specificity, 30% sensitivity). Genomic analysis additionally revealed variability in toxin gene sequences among C. difficile strains, phylogenomic equivalency between isolates from affected patients and carriers, and patient carriage with uncommon environmentally derived C. difficile lineages, as well as presenting opportunities for tracing pathogen transmission events.

CONCLUSION

These results highlight the variable performance of clinical stool-based testing approaches as well as the potential diagnostic utility of whole-genome sequencing as an alternative to conventional testing algorithms.

A Case of Postoperative Methicillin-Resistant Staphylococcus aureus Enterocolitis in an 81-Year-Old Man and Review of the Literature

Patient: Male, 81-year-old

Final Diagnosis: Methicillin-resistant Staphylococcus aureus bacteremia • Methicillin-resistant Staphylococcus aureus enterocolitis

Symptoms: Diarrhea • sepsis

Medication: —

Clinical Procedure: Computed tomography • echocardiography • polymerase chain reaction • whipple procedure

Specialty: Gastroenterology and Hepatology • Infectious Diseases • Surgery

Fecal Gram staining of phagocytosed bacteria to differentiate methicillin-resistant Staphylococcus aureus: A case report

Antibiotic-associated diarrhea is a relatively common problem, and the main bacterial cause is Clostridioides difficile followed by Staphylococcus aureus and other pathogens. The diagnostic procedure for methicillin-resistant S. aureus enteritis is not well established. Phagocytosis is a key antimicrobial process involved in host defense. Phagocytosed bacteria identified by Gram staining are one marker to identify causative microorganisms and select subsequent treatment strategies. However, there are few reports on fecal Gram staining using phagocytosed bacteria as a target for diarrhea treatment. We report the successful use of fecal Gram staining to diagnose and treat methicillin-resistant S. aureus enteritis.

New Approaches to Diagnostics of C.Difficile Infection

Introduction: Clostridium difficile infection (CDI) is the most common infectious cause of diarrhoea in hospitalised patients. It is a severe issue with increasing incidence in healtcare facilities and commmunities. Early and appropriate testing of CDI is very imortant. There are many different approaches that can be used in the CDI laboratory diagnostics. Recently performed studies evaluated diagnostic algorithms to optimize laboratory CDI diagnostics. The aim of the work was to implement an optimal algorithm of testing methods in CDI diagnostics.

Materials and methods: The retrospective analysis of patients’ samples suspected on CDI was carried out in 2017. The data was analysed from the Laboratory Klinicka Biochemia in Zilina. The application of ESCMID re -commendation criteria for algorithm of testing, together with procedures in laboratory practice was carried out.

Results: The analysis of the data showed that the applied algorithm or testing in CDI and highlighted the importance of preanalytic phase, and the evaluation of testing methods and results, together with clinical findings. Two- and three- step algorithm together with cultivation methods were applied. 87,6% of samples could be eva -luated with positive or negative results according to the 2-step algorhitm. Further samples were assessed and tested by ELISA test or PCR method.

Conclusion: CDI represents a significant burden in healthcare facilities. An early diagnostics and interpretation helps to start the early treatment and helps in surveillence of the infection.

Advances in the diagnosis and treatment of Clostridium difficile infections

Clostridium difficile is a leading cause of antibiotic-associated diarrhea worldwide. The diagnosis of C. difficile infection (CDI) requires both clinical manifestations and a positive laboratory test for C. difficile and/or its toxins. While antibiotic therapy is the treatment of choice for CDI, there are relatively few classes of effective antibiotics currently available. Therefore, the development of novel antibiotics and/or alternative treatment strategies for CDI has received a great deal of attention in recent years. A number of emerging agents such as cadazolid, surotomycin, ridinilazole, and bezlotoxumab have demonstrated activity against C. difficile; some of these have been approved for limited clinical use and some are in clinical trials. In addition, other approaches such as early and accurate diagnosis of CDI as well as disease prevention are important for clinical management. While the toxigenic culture and the cell cytotoxicity neutralization assay are still recognized as the gold standard for the diagnosis of CDI, new diagnostic approaches such as nucleic acid amplification methods have become available. In this review, we will discuss both current and emerging diagnostic and therapeutic modalities for CDI.