Colitis Infection Research Articles

The evidence for probiotics in the treatment of digestive disorders in the pediatric population.

Health claims for many probiotic-labeled products are poorly substantiated. This technical review addressed the clinical question: "Do probiotics have a role in the management of the following conditions in childhood?" Evidence supports efficacy for probiotic strains of Saccharomyces boulardii, Lactobacillus reuteri, and Lactobacillus rhamnosus GG for improving outcomes of acute gastroenteritis, of S. boulardii and L. rhamnosus GG for antibiotic-associated diarrhea, and of S. boulardii for Clostridium difficile diarrhea. For functional constipation and GERD, a role for probiotics is questionable as evidence of efficacy is either absent or marginal and as existing treatments are effective. For infantile colic and chronic abdominal pain, where existing treatments have limited efficacy and some important side effects, the use of probiotics, given their safety, is recommended, notwithstanding the evidence is low to moderate. While there is some evidence that probiotics could improve outcomes in the management of celiac disease, obesity, and, to a lesser extent, promotion of growth, their role is adjunctive as dietary management is fundamental. The evidence also supports an adjunctive role for probiotics in the treatment of Helicobacter pylori infection and ulcerative colitis. Decisions on probiotic prescription need to take into account disease tempo, severity, and burden, as well as probiotic strain and dose. Any potential advantage will have to be weighed against the complexity and costs of an additional treatment.

Treatment outcomes of mild to moderate Clostridioides difficile infection in inflammatory bowel disease: an Australian experience.

The incidence of Clostridioides difficile infection (CDI) in inflammatory bowel disease (IBD) is rising and associated with adverse outcomes. Optimal treatment for CDI in IBD remains unknown, with various organisations suggesting vancomycin as first-line therapy. To compare treatment outcomes for metronidazole versus vancomycin in mild to moderate CDI in IBD. A retrospective analysis of IBD patients with CDI between January 2015 and December 2019 was conducted. Laboratory data and clinical outcomes were examined. Forty-seven discrete episodes of CDI in 34 patients occurred during the study period. Fifty-three per cent (18) had Crohn's disease, 44% (15) ulcerative colitis and 3% (1) IBD unclassified. Six per cent (3/47) of CDI cases were severe and excluded. In 68% (30/44) of mild to moderate CDI, metronidazole was prescribed, with treatment failure in 20% (6/30), CDI recurrence in 13% (4/30) and 20% (6/30) experiencing a further CDI episode. Comparatively, vancomycin was prescribed in 23% (10/44) without any treatment failures; however, 10% (1/10) had CDI recurrence and 40% (4/10) experienced another CDI episode. No statistically significant difference was noted between metronidazole and vancomycin therapy for treatment failure (P = 0.31), CDI recurrence (P = 1.0) or further CDI episodes (P = 0.23). Proton-pump inhibitor therapy was the only risk factor associated with a higher rate of the composite outcome and remained significant on multivariate logistic regression (odds ratio 12.99 (95% confidence interval = 1.21-139.97), P = 0.03). Metronidazole compared to vancomycin for treatment of mild to moderate CDI in IBD is effective however may be associated with higher rates of treatment failure.

Opportunistic infections changed before and after SARS-CoV-2 infection in inflammatory bowel disease patients: a retrospective single-center study in China.

SARS-CoV-2 transmission has become a serious worldwide public health concern. However, there is currently insufficient data to determine whether SARS-CoV-2 infection would affect opportunistic infections in inflammatory bowel disease (IBD) patients. A retrospective study included 451 IBD patients (294 UC and 157 CD). The IBD patients were divided into two groups: before SARS-CoV-2 infection and after SARS-CoV-2 infection, and outcomes were measured for these groups. The primary outcome was the presence and distribution of opportunistic infections. The secondary outcomes included factors associated with opportunistic infections, based on which a nomogram prediction model was developed and validated. After SARS-CoV-2 infection, the proportion of IBD patients with opportunistic infections by Clostridium difficile (21.31% vs. 14.01%, p = 0.044) and Epstein-Barr virus (13.93% vs. 4.35%, p = 0.001) was significantly higher compared to that before. Conversely, the proportion of patients with hepatitis B virus (3.69% vs. 10.14%, p = 0.006) and herpes simplex virus type I (1.23% vs. 4.35%, p = 0.04) infections was significantly lower after the infection. Additionally, pre-SARS-CoV-2 infection factors associated with opportunistic infections in IBD include duration of illness, red blood cell count, the presence of comorbid chronic illnesses, and alcohol consumption, while post-SARS-CoV-2 infection, the primary risk factors involve corticosteroid use, red blood cell count, protein level, and high-sensitivity C-reactive protein. After the SARS-CoV-2 infection, there has been a shift in the occurrence of opportunistic infections among IBD patients. It might be attributed to the use of corticosteroids and also the strengthening of containment measures, heightened public health awareness, and widespread vaccination.

Sirtuin 6 inhibits group 3 innate lymphoid cell function and gut immunity by suppressing IL-22 production.

Group 3 innate lymphoid cells (ILC3s) are enriched in the intestinal mucosa and play important roles in host defense against infection and inflammatory diseases. Sirtuin 6 (SIRT6) is a nicotinamide adenine dinucleotide (NAD+)- dependent deacetylase and has been shown to control intestinal epithelial cell differentiation and survival. However, the role of SIRT6 in ILC3s remains unknown. To investigate the role of SIRT6 in gut ILC3s, we generated SIRT6 conditional knockout mice by crossing Rorccre and Sirt6flox/flox mice. Cell number and cytokine production was examined using flow cytometry. Citrobacter rodentium infection and dextran sodium sulfate-induced colitis models were used to determine the role of SIRT6 in gut defense. RT-qPCR, flow cytometry and immunohistochemistry were used to assess the intestinal inflammatory responses. Here we show that SIRT6 inhibits IL-22 expression in intestinal ILC3s in a cell-intrinsic manner. Deletion of SIRT6 in ILC3s does not affect the cell numbers of total ILC3s and subsets, but results in increased IL-22 production. Furthermore, ablation of SIRT6 in ILC3s protects mice against Citrobacter rodentium infection and dextran sodium sulfate-induced colitis. Our results suggest that SIRT6 may play a role in ILC3 function by regulating gut immune responses against bacterial infection and inflammation. Our finding provided insight into the relation of epigenetic regulators with IL-22 production and supplied a new perspective for a potential strategy against inflammatory bowel disease.

Is Helicobacter pylori Infection Associated With Ulcerative Colitis Activity?

Objectives: Epidemiological studies have shown an inverse association between <i>Helicobacter pylori</i> infection and ulcerative colitis (UC). In this study, we investigated the protective effects of H. pylori infection on the severity of UC.Methods: This single-center study included 316 patients with newly diagnosed UC based on findings of colonoscopy and upper endoscopy for H. pylori evaluation between January 1994 and December 2015. Patients’ medical records were retrospectively reviewed, and severity of UC was assessed based on endoscopic findings, clinical symptoms, treatment regimens, and Mayo scores.Results: The prevalence of <i>H. pylori</i> infection in patients with UC was 74/316 (23.4%). Based on upper endoscopic findings, the percentage of patients with duodenal ulcers was significantly higher in the H. pylori positive group than that in the <i>H. pylori</i> negative group (27.0% vs. 11.6%, <i>p</i>=0.022). Disease extent and endoscopic severity showed no significant intergroup difference (<i>p</i>=0.765 and <i>p</i>=0.803, respectively). Endoscopic severity was unaffected by the <i>H. pylori</i> infection status, based on the extent of endoscopically documented disease and endoscopic findings. Furthermore, UC-related symptom severity assessed on the basis of stool frequency, rectal bleeding severity, and rate of admission necessitated by UC aggravation was not associated with <i>H. pylori</i> infection (<i>p</i>=0.185, 0.144, and 0.182, respectively). Use of steroids as induction therapy for severe UC did not differ with regard to <i>H. pylori</i> infection (<i>p</i>=0.327). No intergroup difference was observed in disease severity of UC classified using the Mayo score (<i>p</i>=0.323).Conclusions: <i>H. pylori</i> infection was detected in approximately 25.0% of patients with UC. However, the <i>H. pylori</i> infection status was not associated with the severity of UC based on endoscopic disease activity, patients’ symptoms, steroid use, or the Mayo clinic score.

Navigating the Gastrointestinal Implications of Coronavirus 19: Strategies and Lessons Learned

In 2019, an outbreak of COVID-19 caused by SARS-CoV2 spread worldwide, affecting millions of individuals. This was colloquially termed the “COVID-19 Pandemic.” As the pandemic progressed, multiple variants of SARS-CoV2 continued to evolve, including the most recent JN1, and spread worldwide, causing a broad spectrum of symptoms affecting multiple organ systems. The purpose of this article is to comprehensively explore COVID-19 through the lens of the Gastrointestinal system (GI) and review the treatments. The prevalence of GI symptoms in COVID-affected patients ranged from 28.2% to 50% throughout the pandemic. The predominant symptoms include nausea, diarrhea, reflux, abdominal pain, and emesis. Interestingly, these symptoms persisted for an extended time, sometimes the most bothersome, even after the resolution of an active infection. Due to the nature and prevalence of these symptoms, it is imperative that we understand the mechanism of interaction of SARS CoV2 and the GI system and its pathophysiology. Despite being the less common transmission route, the fecal-oral route is to be considered when devising public health strategies. The term “Long Covid” has been coined due to the long-term symptoms after active infection, and interestingly, GI symptoms have a significant prevalence. Though unclear, the pathogenesis is thought to be due to gut dysbiosis and dysbiosis of the gut-brain connection. In this article, we have also discussed the GI symptoms and treatment of COVID infection in inflammatory bowel disease, pediatric population. We have also discussed guidelines by gastroenterology societies for care prior to, during, and after endoscopy, as well as ostomy care in COVID patients.

S73 The Prevalence and Risk Factors of Clostridium Infection in Inflammatory Bowel Disease: 10 Years of Korean Experience Based on the National Database

S73 The Prevalence and Risk Factors of Clostridium Infection in Inflammatory Bowel Disease: 10 Years of Korean Experience Based on the National Database

S101 Myelosuppression Due to the Use of Azathioprine and COVID Infection and Severe Acute Colitis in a Patient With Ulcerative Colitis: Case Report

S101 Myelosuppression Due to the Use of Azathioprine and COVID Infection and Severe Acute Colitis in a Patient With Ulcerative Colitis: Case Report

S2542 Case of Severe Multifactorial Diarrhea in the Setting of Clostridioides difficile: Infection and Lymphocytic Colitis Unresponsive to Budesonide

S2542 Case of Severe Multifactorial Diarrhea in the Setting of Clostridioides difficile: Infection and Lymphocytic Colitis Unresponsive to Budesonide

S3205 Double Trouble: A Rare Case of Concurrent Severe H. pylori Infection and Ulcerative Colitis as Initial Presentation

S3205 Double Trouble: A Rare Case of Concurrent Severe H. pylori Infection and Ulcerative Colitis as Initial Presentation

S3211 Eosinophilia: A Manifestation of Parasitic Infection or Ulcerative Colitis?

S3211 Eosinophilia: A Manifestation of Parasitic Infection or Ulcerative Colitis?

Risk of Gastrointestinal Infections After Initiating Vedolizumab and Anti-TNFα Agents for Ulcerative Colitis.

Characterize and compare the risk of Clostridioides difficile infection (CDI) and cytomegalovirus colitis (CMVC) after initiation of vedolizumab or anti-tumor necrosis factor (TNF)α agents for ulcerative colitis (UC). Immunosuppression is a risk factor for gastrointestinal infections including CDI and CMVC among patients with UC; however, the risk according to the biological class is poorly understood. A retrospective cohort study of adults with UC involving the initiation of vedolizumab or anti-TNFα agents during June 1, 2014 to December 31, 2020 was conducted at a large academic health system. The primary outcomes for both CDI and CMVC analyses were first CDI or CMVC after biological initiation. The secondary outcome for the CDI analysis was severe CDI (>10,000 white blood cells or serum creatinine >1.5mg/dL). Independent variables included demographics and UC history/severity factors. Inverse probability of treatment weighted Cox regression was performed to assess the hazard of CDI by biological group. Due to few outcomes, CMVC was reported descriptively. A total of 805 UC patients initiated vedolizumab (n=195) or anti-TNFα agents (n=610). There were 43 CDIs and 11 severe CDIs over 1436 patient-years. The inverse probability of treatment weighted Cox regression demonstrated no association between CDI and vedolizumab versus anti-TNFα (hazard ratio 0.33, 95% confidence interval 0.05-2.03), but identified a significantly lower hazard of severe CDI for vedolizumab versus anti-TNFα (hazard ratio 0.10, 95% confidence interval 0.01-0.76). There were 5 cases of CMVC, all in the anti-TNFα group. There was a lower adjusted risk of severe CDI but not total CDI associated with vedolizumab. CMVC was not observed after initiating vedolizumab. These findings may provide reassurance regarding the use of vedolizumab when also considering the risk of gastrointestinal infections.

Clostridium difficile infection and immune mediated diarrhea and colitis in patients with cancer on immune checkpoint inhibitors.

e14683 Background: Immune checkpoint inhibitors (ICIs) have altered the landscape of cancer treatment. ICIs are associated with immune mediated diarrhea and colitis (IMDC) which can be challenging to diagnose and differentiate from other etiologies of diarrhea. Clostridium difficile infection (CDI) is a common cause of diarrhea in patients with cancer and can have similar symptoms. In a similar study, CDI was found to be relatively common in ICI-treated cancer patients and especially those with IMDC requiring immunosuppressants. Our study evaluates the incidence of CDI and IMDC in patients with ICI exposure and compares clinical characteristics between the two to determine risk factors that may predispose patients to CDI or IMDC. Methods: This is a retrospective, single-center study of cancer patients on an ICI from 1/1/2011 to 4/7/2022 who were tested for Clostridium difficile with stool nucleic acid amplification tests during or after treatment with an ICI. Patients were determined to have CDI if clinically suspected and had to have a positive stool GDH Ag along with positive C. difficile toxins A & B or a positive stool C. difficile toxin B gene. Patients with positive GDH Ag in the stool but with negative toxins A&B were determined to be colonized. The diagnosis of IMDC was based on the clinical presentation and had to be made by the treating oncologist. Results: 375 patients met our study criteria and got CDI testing at any point during or after ICI exposure. 27 patients tested positive for CDI, whereas 24 were colonized. 105 patients were determined to have IMDC and 97/105 received treatment with steroids or immunosuppressants. Among patients determined to have IMDC, 6 were colonized for clostridium difficile. There were no patients with IMDC who were also positive for clostridium difficile. 71 patients were on a dual ICI regimen whereas 304 patients were on a single ICI. In patients on the dual ICI regimen, 67.6% were diagnosed with IMDC when compared to patients on a single ICI regimen where 18.8% of patients were diagnosed with IMDC (p<0.0001). The absolute lymphocyte count on the day of CDI testing was 1.185 ± 0.066 in the IMDC group when compared to 0.948 ± 0.044 in the non-IMDC group (p=0.003). The mean duration of diarrhea was longer in the IMDC group at 16.905 ± 1.211 days when compared to the CDI group at 9.852 ± 2.387 days (p= 0.0094). Smoking status, sex, history of autoimmunity, and history of prior immune related adverse events did not impact incidence of IMDC or CDI. Conclusions: IMDC was a common cause of diarrhea in patients with ICI exposure who were tested for CDI. We did not find IMDC to be a risk factor for CDI. IMDC has a longer duration of diarrhea and colitis symptoms when compared to CDI. The absolute lymphocyte count on symptom onset is higher in patients with IMDC when compared to patients with CDI and may be useful in identifying patients with IMDC earlier.

Proton pump Inhibitors and Risk of Enteric Infection in Inflammatory Bowel Disease: A Self-controlled Case Series.

We tested whether proton pump inhibitors (PPIs) are associated with enteric infections among those with inflammatory bowel disease (IBD), after adequately accounting for baseline differences between PPI users and nonusers. This was a self-controlled case series, with each patient serving as their own control. Ambulatory patients with IBD were included if they were tested for enteric infection by multiplex polymerase chain reaction testing panel (GIPCR) and/or Clostridoides difficile toxin PCR from 2015 to 2019 and received PPIs for some but not all of this period. Rates of enteric infections were compared between the PPI-exposed period vs pre- and post-PPI periods identical in duration to the exposed period. Conditional Poisson regression was used to adjust for time-varying factors. Two hundred twenty-one IBD patients were included (49% ulcerative colitis, 46% Crohn's disease, and 5% indeterminate colitis). The median PPI duration was 7 months (interquartile range 4 to 11 months). A total of 25 (11%) patients had a positive GIPCR or C. difficile test in the PPI period, 9 (4%) in the pre-PPI period, and 8 (4%) in the post-PPI period. Observed incidence rates for enteric infections were 2.5, 7.4, and 2.2 per 100 person years for the pre-PPI, PPI, and post-PPI periods, respectively (adjusted incidence rate ratios, 2.8; 95% confidence interval [CI] 1.3-6.0) for PPI vs pre-PPI and 2.9 (95% CI, 1.3-6.4) for PPI vs post-PPI). The adjusted absolute excess risk associated with PPIs was 4.9 infections per 100 person years. Proton pump inhibitors were associated with a 3-fold increased risk for enteric infection among those with IBD but had a modest absolute risk.

A Pregnant Patient with COVID-19 Induced Colitis and Spontaneous Preterm Birth

Background: Although COVID-19 infection typically presents with respiratory symptoms, gastrointestinal symptoms are a part of the disease spectrum. Case: An otherwise healthy pregnant patient presented with diffuse abdominal pain at 24+1 weeks gestation. She was diagnosed with COVID-19 infection and diffuse colitis. Her symptoms worsened despite treatment, and she delivered a live male fetus at 24+2 weeks. Conclusion: COVID-19 infection can adversely affect maternal and fetal status in pregnancy due to its inflammatory response and resulting vascular dysfunction. COVID-19 infection should be suspected in a pregnant patient with gastrointestinal symptoms to avoid delay in diagnosis and treatment.

Development and Validation of a Remote Monitoring Tool for Assessment of Mild, Moderate, and Severe Infections in Inflammatory Bowel Disease.

Immunomodulators and biologics are cornerstones in the management of inflammatory bowel disease [IBD], but are associated with increased risk of infections. Post-marketing surveillance registries are pivotal to assess this risk, yet mainly focus on severe infections. Data on the prevalence of mild and moderate infections are scarce. We developed and validated a remote monitoring tool for real-world assessment of infections in IBD patients. A 7-item Patient-Reported Infections Questionnaire [PRIQ] covering 15 infection categories was developed with a 3-month recall period. Infection severity was defined as mild [self-limiting or topical treatment], moderate [oral antibiotics, antivirals, or antifungals], or severe [hospitalisation or intravenous treatment]. Comprehensiveness and comprehensibility were ascertained through cognitive interviewing of 36 IBD outpatients. After implementation in the telemedicine platform myIBDcoach, a prospective, multicentre cohort study was performed between June 2020 and June 2021 in 584 patients, to assess diagnostic accuracy. Events were cross-checked with general practitioner and pharmacy data [gold standard]. Agreement was evaluated using linear-weighted kappa with cluster-bootstrapping to account for within-patient level correlation. Patient understanding was good and interviews did not result in reduction of PRIQ items. During validation, 584 IBD patients {57.8% female, mean age 48.6 (standard deviaton [SD]: 14.8), disease duration 12.6 years [SD: 10.9]} completed 1386 periodic assessments, reporting 1626 events. Linear-weighted kappa for agreement between PRIQ and gold standard was 0.92 (95% confidence interval [CI] 0.89-0.94). Sensitivity and specificity for infection [yes/no] were 93.9% [95% CI 91.8-96.0] and 98.5% [95% CI 97.5-99.4], respectively. The PRIQ is a valid and accurate remote monitoring tool to assess infections in IBD patients, providing means to personalise medicine based on adequate benefit-risk assessments.

Family of hNQO1 Activatable Near-Infrared Fluoro-Photoacoustic Probes for Diagnosis of Wound Infection and Ulcerative Colitis.

Bacterial infections can easily occur when patients mishandle wounds or eat moldy food. The prompt diagnosis of a bacterial infection could effectively reduce the risk of possible anatomical damage. However, non-invasive early detection of bacterial infections is difficult to achieve due to the lack of favorable tools. Here, we designed two hNQO1 fluorescent probes (RX2 and RX3) to visualize bacterial infection after deep learning on the pathogenesis of bacterial infection. RX2 and RX3 enable early detection of bacterial infection and are verified to be, respectively, suitable for fluorescence imaging (FLI) and photoacoustic imaging (PAI) by comparing the signal-to-background ratio of both probes in a mouse model of myositis caused by Escherichia coli infection. In view of the difference in penetration depth between the two imaging modalities, we further applied RX2 for FLI of E. coli-infected wounds and RX3 for PAI of E. coli-infected inflammatory bowel disease, suggesting the great potential of both probes for early diagnosis of bacterial infections.

The Prevalence and Risk Factors of Clostridioides difficile Infection in Inflammatory Bowel Disease: 10-Year South Korean Experience Based on the National Database.

Few studies evaluate the epidemiology and risk factors of Clostridioides difficile infection (CDI) in Asian patients with inflammatory bowel disease (IBD). We investigated the year-end prevalence, cumulative incidence and risk factors of CDI in Asian patients with IBD using a large-scale population-based cohort in Korea. Using the National Health Insurance Service database, we identified patients with IBD and sex- and age-matched controls without IBD between 2008 and 2018. The year-end prevalence and cumulative incidence of CDI were compared among patients with Crohn's disease (CD) and ulcerative colitis (UC) with controls. The risk factors for CDI were evaluated. Among the 54,836 patients with IBD and 109,178 controls, CDI occurred in 293 patients with IBD and 87 controls. The annual year-end prevalence of CDI in patients with IBD increased from 8.6/10,000 persons in 2008 to 22.3/10,000 persons in 2018. The risk of CDI was higher in both patients with CD and UC than that in the matched controls (hazard ratio [HR], 7.285; 95% confidence interval [CI], 5.388-9.851; P < 0.001 and HR, 7.487; 95% CI, 5.796-9.670; P < 0.001, respectively). Among patients with IBD, the risk factors for CDI included older age, female sex, high Charlson comorbidity index score, and IBD-related medications including oral 5-aminosalicylic acid, immunomodulatory agents, biologics, and steroids used for > 90 days. The risk of CDI in Korean patients with IBD was approximately seven times higher than that in controls without IBD, and the annual year-end prevalence of CDI continuously increased from 2008 to 2018.

S1032 Clostridium difficile Infection in Inflammatory Bowel Disease, Risk Analysis and Determination of Complications Based on Nationwide Inpatient Sample Database

S1032 Clostridium difficile Infection in Inflammatory Bowel Disease, Risk Analysis and Determination of Complications Based on Nationwide Inpatient Sample Database

S2946 Chronic Graft versus Host Disease Masquerading CMV Colitis After Liver Transplantation: A Clinical Challenge

Introduction: Graft versus host disease (GVHD) after solid organ transplantation is a rare but serious complication with high mortality that typically occurs 1-8 weeks post liver transplantation (LT). Steroids are first line treatment and data on second line treatment are less widely available. Case Description/Methods: 54-years-old woman with history of alcohol-related cirrhosis went under LT with a positive cytomegalovirus (CMV) and HCV male donor. She was discharged home without any major complications. Immune suppression included tacrolimus, mycophenolate mofetil, (MMF) and prednisone taper. She was admitted to hospital 3 months later with diarrhea and acute kidney injury. C. difficile PCR was negative, CMV PCR was positive, and biopsies obtained during colonoscopy revealed severe CMV colitis. She was started on ganciclovir. Tacrolimus was reduced and MMF was discontinued. Fever and diarrhea were continued despite CMV treatment and later she developed a diffuse skin rash. This initially thought to be due to ganciclovir, but skin biopsy was concerning for GVHD. Gastric and colon biopsies and peripheral blood chimerism (donor T cell 81.3%; normal < 1%) confirmed GVHD. She was started on steroid therapy with minimal improvement in diarrhea as well as minimal improvement after the addition of topical budesonide and octreotide. Her course was complicated by posterior reversible encephalopathy syndrome and status epilepticus and was intubated. Tacrolimus was stopped. She then developed pancytopenia with severe neutropenia despite discontinuation of ganciclovir. Bone marrow biopsy showed 10.7% donor alleles. Infliximab was initiated. Stool output decreased and neutropenia resolved after 1 week. Seizures were controlled and she was extubated. Chimerism analysis of peripheral blood after 11 days showed significant reduction of donor T cells (58.5%). However, after 2 weeks, diarrhea worsened and donor T cells increased to 70.9% in blood. Ruxolitinib and cyclosporin were started in addition to infliximab but she developed septic shock and expired (Figure). Discussion: Persistent diarrhea and skin rash after liver transplantation may be signs of GVHD but these symptoms can also be seen in more common conditions such as C. difficile infection, drug reaction, and CMV colitis. Biopsy and chimerism analysis might both be needed for diagnosis of GVHD in patients with low pretest probability. Post LT GVHD that is refractory to steroid therapy may respond to infliximab. Sepsis is the most common cause of mortality in LT GVHD.Figure 1.: Sample micrographs from short tandem repeat (STR) testing (chimerism analysis) on isolated T cells from peripheral blood.