Histologic findings and clinical characteristics in acutely symptomatic ulcerative colitis patients with superimposed Clostridium difficile infection

Diagnostic Guidance for C. difficile Infections

Diagnosis of Clostridioides difficile infection (CDI) can be challenging. First of all, there has been debate on which of the two reference assays, cell cytotoxicity neutralization assay (CCNA) or toxigenic culture (TC), should be considered the gold standard for CDI detection. Although the CCNA suffers most from suboptimal storage conditions and subsequent toxin degradation, TC is reported to falsely increase CDI detection rates as it cannot differentiate CDI patients from patients asymptomatically colonised by toxigenic C. difficile. Several rapid assays are available for CDI detection and fall into three broad categories: (1) enzyme immunoassays for glutamate dehydrogenase, (2) enzyme immunoassays or single-molecule array assays for toxins A/B and (3) nucleic acid amplification tests detecting toxin genes. All three categories have their own limitations, being suboptimal specificity and/or sensitivity or the inability to discern colonised patients from CDI patients. In light of these limitations, multi-step algorithmic testing has been advocated by international guidelines (IDSA/SHEA and ESCMID) in order to optimize diagnostic accuracy. As a result, a survey performed in 2018-2019 in Europe revealed that most of all hospital sites reported using more than one test to diagnose CDI. CDI incidence rates are also influenced by sample selection criteria, as several studies have shown that if not all unformed stool samples are tested for CDI, many cases may be missed due to an absence of clinical suspicion. Since methods for diagnosing CDI remain imperfect, there has been a growing interest in alternative testing strategies like faecal microbiota biomarkers, immune modulating interleukins, cytokines and imaging methods. At the moment, these alternative methods might play an adjunctive role, but they are not suitable to replace conventional CDI testing strategies.

Infectious Disease Pathology of the Gastrointestinal Tract: Diagnosing the Challenging Cases

Infectious diseases of the GI tract mimic a variety of other GI diseases, including chronic idiopathic inflammatory bowel disease and ischemia. It can be challenging to identify pathogens in tissue sections as well, as many trainees are not exposed to infectious disease pathology other than in the context of microbiology. Our ability to diagnose infections in formalin fixed, paraffin embedded material has grown exponentially with the advent of new histochemical and immunohistochemical stains, as well as more options for molecular testing. Correlating these diagnostic techniques with morphology has led to increasing understanding of the histologic patterns that are associated with specific pathogens.

Histological features of Clostridioides difficile colitis in patients with inflammatory bowel disease

AIMS

Patients with inflammatory bowel disease (IBD) are at increased risk for Clostridioides difficile infection, although clinically important infections can be difficult to recognise. C. difficile infection does not produce pseudomembranes when it occurs in IBD patients. These individuals may also be colonised by the organism, in which case diarrhoeal symptoms are not necessarily attributed to C. difficile. We performed this study to determine whether any features distinguished C. difficile-associated colitis from an IBD flare.

METHODS AND RESULTS

We reviewed the clinical, endoscopic and biopsy findings from 50 patients with established IBD and worsening diarrhoea, including 22 with concurrent positive C. difficile stool toxin polymerase chain reaction (PCR) assays and 28 with negative C. difficile assay results. We found that C. difficile-infected patients had symptoms and endoscopic findings that were indistinguishable from active IBD. Although most biopsy samples from patients with C. difficile infection showed chronic active colitis indistinguishable from IBD, some displayed neutrophilic infiltrates unaccompanied by plasma cell-rich inflammation involving superficial (41%) and crypt (18%) epithelium as well as neutrophilic infiltrates within lamina propria distant from foci of cryptitis (32%). All three of these features were significantly more common among infected than uninfected patients (4, 0 and 4%; P = 0.002, P = 0.03 and P = 0.02, respectively).

CONCLUSIONS

Although colonic biopsies from IBD patients with C. difficile infection usually lack features that aid distinction from colitic flares, some cases show an acute colitis pattern not seen in IBD alone. When identified in biopsies from symptomatic IBD patients, these changes should alert pathologists to the possibility of this clinically important infection.

Non-neoplastic colorectal disease biopsies: evaluation and differential diagnosis

A wide variety of non-neoplastic conditions may be encountered on colorectal biopsy encompassing idiopathic, infectious, vascular and immune-mediated aetiologies. Although interpretation of such biopsies may be challenging, appreciation of the dominant pattern of injury and subsequent host response may allow for a more focused histological diagnosis in the correct clinical and endoscopic setting. This article aims to provide a systematic, methodical approach to the assessment of such biopsies, concentrating mainly on diagnoses other than inflammatory bowel disease.

Histopathological Mimics of Inflammatory Bowel Disease

This review article discusses the challenges of making a firm histopathological diagnosis of inflammatory bowel disease (IBD) on biopsy and resection material and the importance of its distinction from a range of other inflammatory and infective conditions that may closely mimic IBD. In many cases, the diagnosis of ulcerative colitis or Crohn's disease is straightforward, especially when patients have a typical presentation and characteristic histopathological features. Knowledge of the full clinical history is very important, particularly past and recent medical history, drug history, foreign travel, or known contact with individuals with specific infection. Discussion of all cases of suspected IBD within a multidisciplinary team meeting is required to ensure that clinical, radiological, and pathological features can be correlated. Mimics of IBD can be divided into 4 categories: 1) those due to specific infection, 2) those due to a specific localized inflammatory process, 3) those due to iatrogenic causes, and 4) other rarer causes. Accurate diagnosis of IBD and exclusion of these mimics are crucial for patient management. Once a diagnosis of IBD has been proffered by a pathologist, it is very difficult to "undiagnose" the condition when an alternative diagnosis or "mimic" has been subsequently identified. The histological diagnosis of each of these IBD mimics is discussed in detail, with guidance on how to avoid the pitfall of missing these sometimes very subtle and "difficult to diagnose" conditions.

Clostridium difficile Enterocolitis in a Captive Geoffroy's Spider Monkey (Ateles geoffroyi) and Common Marmosets (Callithrix jacchus)

Clostridium difficile is a well-documented cause of enterocolitis in several species, including humans, with limited documentation in New World nonhuman primates. We report several cases of C. difficile-associated pseudomembranous enterocolitis, including a case in a Geoffroy's spider monkey (Ateles geoffroyi) and several cases in common marmosets (Callithrix jacchus). The histologic lesions included a spectrum of severity, with most cases characterized by the classic "volcano" lesions described in humans and several other animal species. C. difficile was isolated from the colon of the spider monkey, while the presence of toxin A or toxin B or of the genes of toxin A or B by polymerase chain reaction served as corroborative evidence in several affected marmosets. C. difficile should be considered a cause of enterocolitis in these species.

Diagnostic Guidance for C. difficile Infections

Diagnosis of Clostridium difficile infection (CDI) can be challenging. First of all, there has been debate on which of the two reference assays, cell cytotoxicity neutralization assay (CCNA) or toxigenic culture (TC) should be considered the gold standard for CDI detection. Although the CCNA suffers most from suboptimal storage conditions and subsequent toxin degradation, TC is reported to falsely increase CDI detection rates as it cannot differentiate CDI patients from patients asymptomatically colonised by toxigenic C. difficile. Several rapid assays are available for CDI detection and fall into three broad categories: (1) enzyme immunoassays for glutamate dehydrogenase, (2) enzyme immunoassays for toxins A/B and (3) nucleic acid amplification tests detecting toxin genes. All three categories have their own limitations, being suboptimal specificity and/or sensitivity or the inability to discern colonised patients from CDI patients. In light of these limitations, multi-step algorithmic testing has now been advocated by international guidelines in order to optimize diagnostic accuracy. Despite these recommendations, testing methods between hospitals vary widely, which impacts CDI incidence rates. CDI incidence rates are also influenced by sample selection criteria, as several studies have shown that if not all unformed stool samples are tested for CDI, many cases may be missed due to an absence of clinical suspicion. Since methods for diagnosing CDI remain imperfect, there has been a growing interest in alternative testing strategies like faecal biomarkers, immune modulating interleukins, cytokines and imaging methods. At the moment, these alternative methods might play an adjunctive role, but they are not suitable to replace conventional CDI testing strategies.

Management of inflammatory bowel disease with Clostridium difficile infection

AIM

To address the management of Clostridium difficile (C. difficile) infection (CDI) in the setting of suspected inflammatory bowel disease (IBD)-flare.

METHODS

A systematic search of the Ovid MEDLINE and EMBASE databases by independent reviewers identified 70 articles including a total of 932141 IBD patients or IBD-related hospitalizations.

RESULTS

In those with IBD, CDI is associated with increased morbidity, including subsequent escalation in IBD medical therapy, urgent colectomy and increased hospitalization, as well as excess mortality. Vancomycin-containing regimens are effective first-line therapies for CDI in IBD inpatients. No prospective data exists with regards to the safety or efficacy of initiating or maintaining corticosteroid, immunomodulator, or biologic therapy to treat IBD in the setting of CDI. Corticosteroid use is a risk factor for the development of CDI, while immunomodulators and biologics are not.

CONCLUSION

Strong recommendations regarding when to initiate IBD specific therapy in those with CDI are precluded by a lack of evidence. However, based on expert opinion and observational data, initiation or resumption of immunosuppressive therapy after 48-72 h of targeted antibiotic treatment for CDI may be considered.

Infection with Toxin A-Negative, Toxin B-Negative, Binary Toxin-Positive Clostridium difficile in a Young Patient with Ulcerative Colitis

Large clostridial toxin-negative, binary toxin-positive (A(-) B(-) CDT(+)) strains of Clostridium difficile are almost never associated with clinically significant C. difficile infection (CDI), possibly because such strains are not detected by most diagnostic methods. We report the isolation of an A(-) B(-) CDT(+) ribotype 033 (RT033) strain of C. difficile from a young patient with ulcerative colitis and severe diarrhea.