IBD Flare Infection Testing

For Crohn disease with symptoms suggesting active disease, obtain stool testing for fecal pathogens and C. difficile and measure fecal calprotectin (FC). The purpose is to identify an enteric infection that changes immediate treatment and to establish whether objective intestinal inflammation accompanies symptoms. Initial laboratory evaluation should also assess inflammation, anemia, dehydration, and malnutrition. Wolters KluwerWolters KluwerACG Clinical Guideline: Management of Crohn's Disease in Adults

The threshold to test should be low because infectious enteritis and colitis overlap clinically with IBD activity. Routine clinical and laboratory features did not predict infectious colitis in a hospitalized flare cohort, so neither IBD phenotype, biologic exposure, smoking history, nor routine admission findings should be used to omit infection testing. Oxford AcademicOxford AcademicP894 Diagnostic yield of routine stool pathogen tests during the relapse of Inflammatory Bowel Disease | Journal of Crohn's and Colitis | Oxford Academic

In hospitalized IBD, perform stool culture, two-step C. difficile testing, and cross-sectional imaging as part of the initial evaluation. This combination addresses two simultaneous questions: whether infection is driving symptoms and whether severe inflammation has produced a complication requiring urgent procedural or surgical management. NEJMNEJMCaring for Adults Hospitalized with Inflammatory Bowel Disease | NEJM Clinician

Use a two-step C. difficile testing strategy for hospitalized IBD. C. difficile infection is associated with increased hospitalization, therapy intensification or failure, and surgical rates in IBD; patients with IBD also have greater risk of severe and recurrent CDI than patients without IBD. NEJM+1NEJMCaring for Adults Hospitalized with Inflammatory Bowel Disease | NEJM ClinicianScienceDirectAGA Clinical Practice Update on Management of Clostridioides difficile Infection in Inflammatory Bowel Disease: Expert Review

A positive C. difficile result should not automatically end the assessment for concomitant IBD activity. CDI can be the principal cause of diarrhea, coexist with active colitis, or reveal a patient whose inflammatory disease needs reassessment after infection-directed management. Follow clinical trajectory and objective inflammatory assessment rather than symptoms alone when deciding whether IBD therapy requires adjustment. ScienceDirect+1ScienceDirectAGA Clinical Practice Update on Management of Clostridioides difficile Infection in Inflammatory Bowel Disease: Expert ReviewScienceDirectAGA Clinical Practice Update on Functional Gastrointestinal Symptoms in Patients With Inflammatory Bowel Disease: Expert Review - ScienceDirect

For recurrent CDI in IBD, microbiota-directed treatment is an evolving management area. The AGA review identifies unapproved fecal microbiota transplantation and FDA-approved donor-derived therapies as options of interest for recurrent CDI, but the choice requires infection-specific management and individualized assessment of active IBD. ScienceDirectScienceDirectAGA Clinical Practice Update on Management of Clostridioides difficile Infection in Inflammatory Bowel Disease: Expert Review

FC is a neutrophil-derived marker of intestinal inflammation. In Crohn disease, an FC cutoff above 50-100 μg/g is recommended to differentiate inflammatory from noninflammatory disease of the colon. Its value is greatest when symptoms are discordant with CRP or when the decision is whether to proceed to endoscopic or radiologic reassessment. Wolters KluwerWolters KluwerACG Clinical Guideline: Management of Crohn's Disease in Adults

In symptomatic IBD, FC is more sensitive for endoscopically defined activity than CRP: pooled sensitivity and specificity were 0.88 and 0.73 for FC versus 0.49 and 0.92 for CRP. FC was more sensitive in ulcerative colitis than Crohn disease. A low CRP therefore does not reliably exclude active mucosal disease, whereas an elevated FC should prompt consideration of inflammation from IBD or another intestinal inflammatory process. Wolters Kluwer+1Wolters KluwerC-Reactive Protein, Fecal Calprotectin, and Stool... : American Journal of GastroenterologyWolters KluwerACG Clinical Guideline: Management of Crohn's Disease in Adults

Do not interpret FC as disease-specific. It reflects neutrophilic intestinal inflammation and can rise with infectious colitis; its correlation with histology is less satisfactory in Crohn disease because of patchy disease and limited assessment of the small bowel by colonic biopsies. Use FC alongside stool testing, disease distribution, imaging, and endoscopy rather than as a stand-alone declaration of relapse. PubMedPubMedThe Use of Fecal Calprotectin in Inflammatory Bowel Disease - PMC

For ulcerative colitis in remission, an FC concentration above 321 mg/kg predicted relapse at both 6 and 12 months in one study. This prognostic association can support closer reassessment, but it should not replace direct evaluation when an acute infectious or structural cause of symptoms is plausible. PubMedPubMedFecal Calprotectin Predicts Relapse and Histological Mucosal Healing in Ulcerative Colitis - PubMed

When enteric infection has been excluded yet symptoms persist, follow a stepwise objective assessment: FC, endoscopy with biopsy, and cross-sectional imaging. This approach prevents escalation of immunosuppressive therapy for functional gastrointestinal symptoms, bile-acid or motility-related symptoms, structural disease, or inflammation missed by symptom-based assessment. ScienceDirectScienceDirectAGA Clinical Practice Update on Functional Gastrointestinal Symptoms in Patients With Inflammatory Bowel Disease: Expert Review - ScienceDirect

Use standardized endoscopic activity scores when endoscopy is performed to document baseline severity and treatment response. The Mayo Endoscopic Subscore and Ulcerative Colitis Endoscopic Index of Severity are used in ulcerative colitis; the Simple Endoscopic Score for Crohn's Disease provides standardized Crohn disease assessment. These scores improve uniformity of reporting and are used to assess treatment efficacy and prognosis. ScienceDirectScienceDirectAGA Clinical Practice Update on Endoscopic Scoring Systems in Inflammatory Bowel Disease: Commentary - ScienceDirect

Functional symptoms remain possible when objective inflammatory activity is not demonstrated. A low-FODMAP diet may be offered with attention to nutritional adequacy, and cognitive behavioral therapy, hypnotherapy, or mindfulness therapy may be considered. Do not offer fecal microbiota transplantation for functional GI symptoms in IBD outside an infection-directed indication. ScienceDirectScienceDirectAGA Clinical Practice Update on Functional Gastrointestinal Symptoms in Patients With Inflammatory Bowel Disease: Expert Review - ScienceDirect

For hospitalized IBD, pair stool culture and two-step C. difficile testing with cross-sectional imaging because toxic megacolon, abscess, and obstruction require management beyond routine flare treatment. Early multidisciplinary assessment by gastroenterology and surgery is recommended around day 3 of corticosteroid therapy for severe disease requiring rescue or operative planning. NEJM+1NEJMCaring for Adults Hospitalized with Inflammatory Bowel Disease | NEJM ClinicianPubMedWSES-AAST guidelines: management of inflammatory bowel disease in the emergency setting

Reserve antibiotics for documented or strongly suspected superinfection, intra-abdominal abscess, or sepsis rather than routine luminal IBD activity. Select agents according to local epidemiology and resistance patterns, with duration determined by clinical and biochemical response; antifungals are reserved for high-risk patients, including those with bowel perforation and recent steroid exposure. PubMedPubMedWSES-AAST guidelines: management of inflammatory bowel disease in the emergency setting

Administer pharmacologic venous thromboembolism prophylaxis with low-molecular-weight heparin as soon as possible in complicated IBD and emergency presentations. Hospitalization for a flare is a high-risk state for VTE, and systemic prophylaxis is recommended even when the admission is driven by active intestinal disease. PubMed+1PubMedWSES-AAST guidelines: management of inflammatory bowel disease in the emergency settingPubMedCommon Mistakes in Managing Patients with Inflammatory Bowel Disease