Bacteroides ovatus Promotes IL-22 Production and Reduces Trinitrobenzene Sulfonic Acid-Driven Colonic Inflammation.

The intestinal microbiota influences the development and function of the mucosal immune system. However, the exact mechanisms by which commensal microbes modulate immunity is not clear. We previously demonstrated that commensal Bacteroides ovatus ATCC 8384 reduces mucosal inflammation. Herein, we aimed to identify immunomodulatory pathways employed by B. ovatus. In germ-free mice, mono-association with B. ovatus shifted the CD11b+/CD11c+ and CD103+/CD11c+ dendritic cell populations. Because indole compounds are known to modulate dendritic cells, B. ovatus cell-free supernatant was screened for tryptophan metabolites by liquid chromatography-tandem mass spectrometry and larger quantities of indole-3-acetic acid were detected. Analysis of cecal and fecal samples from germ-free and B. ovatus mono-associated mice confirmed that B. ovatus could elevate indole-3-acetic acid concentrations in vivo. Indole metabolites have previously been shown to stimulate immune cells to secrete the reparative cytokine IL-22. Addition of B. ovatus cell-free supernatant to immature bone marrow-derived dendritic cells stimulated IL-22 secretion. The ability of IL-22 to drive repair in the intestinal epithelium was confirmed using a physiologically relevant human intestinal enteroid model. Finally, B. ovatus shifted the immune cell populations in trinitrobenzene sulfonic acid-treated mice and up-regulated colonic IL-22 expression, effects that correlated with decreased inflammation. Our data suggest that B. ovatus-produced indole-3-acetic acid promotes IL-22 production by immune cells, yielding beneficial effects on colitis.

Trends and Disparities in Pediatric Nonalcoholic Fatty Liver Disease-Associated Hospitalizations in the United States.

OBJECTIVE: Non-alcoholic fatty liver disease (NAFLD) represents a spectrum of disease characterized by accumulation of fat in the liver and is associated with co-morbidities linked to metabolic syndrome. The prevalence of NAFLD in children has increased in the United States over time and with marked racial differences observed in geographically limited studies. This study aims to provide a current, nation-wide analysis of temporal trends of pediatric NAFLD-related hospitalizations and associated co-morbidities as well as assess for racial/ethnic disparities. METHODS: A cross-sectional study was conducted using the National Inpatient Sample (NIS) from 2004 to 2018 and included NAFLD-associated hospitalizations of children ages 0-17 years of age based on ICD-9/10 diagnosis codes. Rates and patient characteristics analyzed via descriptive statistics and associations via survey logistic regression. Temporal trends assessed via joinpoint regression. RESULTS: There was an overall increase in pediatric NAFLD-associated hospitalizations with an average annual percent change (AAPC) of 6.6 with highest rates among Hispanic patients (AAPC = 11.1) compared to NH-White (AAPC = 4.1) and NH-Black (AAPC = 2.1). Analysis of race/ethnicity and NAFLD hospitalization showed an increased association in Hispanic patients (odds ratio [OR] = 1.64, 95% confidence interval [CI] = 1.51-1.77) and a decreased association in non-Hispanic (NH)-Black patients (OR = 0.49, 95% CI = 0.45-0.54) when compared to NH-White patients. CONCLUSION: Utilizing a nation-wide database we demonstrated significant increases in NAFLD-associated hospitalizations with highest prevalence and rates seen in Hispanic patients. In addition, sex and comorbidities showed notable correlation to these hospitalization rates displaying the need for further studies on these relationships and highlights the potential for interventions aimed at high-risk groups.

Fecal Microbiota Transplantation Commonly Failed in Children With Co-Morbidities.

OBJECTIVES: Fecal microbiota transplantation (FMT) is arguably the most effective treatment for recurrent Clostridioides difficile infection (rCDI). Clinical reports on pediatric FMT have not systematically evaluated microbiome restoration in patients with co-morbidities. Here, we determined whether FMT recipient age and underlying co-morbidity influenced clinical outcomes and microbiome restoration when treated from shared fecal donor sources. METHODS: Eighteen rCDI patients participating in a single-center, open-label prospective cohort study received fecal preparation from a self-designated (single case) or two universal donors. Twelve age-matched healthy children and four pediatric ulcerative colitis (UC) cases from an independent serial FMT trial, but with a shared fecal donor were examined as controls for microbiome restoration using 16S rRNA gene sequencing of longitudinal fecal specimens. RESULTS: FMT was significantly more effective in rCDI recipients without underlying chronic co-morbidities where fecal microbiome composition in post-transplant responders was restored to levels of healthy children. Microbiome reconstitution was not associated with symptomatic resolution in some rCDI patients who had co-morbidities. Significant elevation in Bacteroidaceae, Bifidobacteriaceae, Lachnospiraceae, Ruminococcaceae, and Erysipelotrichaceae was consistently observed in pediatric rCDI responders, while Enterobacteriaceae decreased, correlating with augmented complex carbohydrate degradation capacity. CONCLUSION: Recipient background disease was a significant risk factor influencing FMT outcomes. Special attention should be taken when considering FMT for pediatric rCDI patients with underlying co-morbidities.

Fecal microbiota transplantation in a toddler after heart transplant was a safe and effective treatment for recurrent Clostridiodes difficile infection: A case report.

Pediatric recipients of SOT have a significantly increased risk of Clostridiodes (formerly Clostridium) difficile infection (CDI), which is associated with adverse outcomes after SOT. Alterations to the intestinal microbiota community structure increase the risk of CDI. FMT is a safe and effective treatment for recurrent CDI in immunocompetent children and adults. While there are increasing data that FMT in immunosuppressed patients is safe and effective without increased risk of infection, data regarding safety and efficacy of FMT in children after SOT are limited. To our knowledge, we report the youngest immunocompromised patient to undergo FMT and the third overall case of FMT in a child after HTx. Our patient presented with five episodes of rCDI in 6 months, and 16S rRNA genetic analysis revealed significant loss of overall microbiota community structure and diversity prior to FMT compared with a donor and a healthy, age-matched control. After FMT, marked and prolonged (at least 16 months) shifts in the recipient microbiota community structure and diversity were evident, approaching that of donor and healthy, age-matched control. FMT was well tolerated, restored microbial diversity without any graft or transplant complications, and prevented further rCDI episodes after more than 4 years of follow-up.

Granulomatous Upper Gastrointestinal Inflammation in Pediatric Ulcerative Colitis.

OBJECTIVES: Differentiating ulcerative colitis (UC) and Crohn disease (CD) can be clinically challenging, especially in children. Granulomatous inflammation has traditionally been attributed to CD. Crypt-associated giant cells and granulomas, however, have been observed in colonic biopsies of patients with UC. This phenomenon has not been described in the upper gastrointestinal (UGI) tract with UC. METHODS: Seven pediatric patients with UC with granulomatous UGI (gUGI) lesions were identified. Diagnosis of UC was based on symptoms, clinical course, laboratory results, imaging, and endoscopy. We compared the gUGI patients to a large cohort of pediatric patients with UC (n = 149). RESULTS: All fully evaluated cases were associated with bloody diarrhea and moderate to severe pancolitis. Gastric and/or duodenal biopsies demonstrated giant cells or granulomas near gland destruction. Small bowel imaging did not reveal any involvement. The majority of cases responded to standard medical therapies, except for 2 patients (28.6%) who required total colectomy. Acute severe, refractory colitis (ie, colectomy within 1 month of presentation) was significantly more common in the gUGI group than the large pediatric UC group (28.6% vs 1.3%, Fisher exact P = 0.01). CONCLUSIONS: This is the first report of pediatric UC-associated granulomatous inflammation in the UGI tract. We speculate that these lesions represent extracolonic manifestations of intense colonic disease. These atypical findings expand the diagnostic considerations that should be incorporated during the differentiation between UC and CD in the pediatric age group.

Unique Inflammatory Bowel Disease Phenotype of Pediatric Primary Sclerosing Cholangitis: A Single-Center Study.

OBJECTIVES: In adults, primary sclerosing cholangitis (PSC), a cholestatic liver disease characterized by inflammation/fibrosis of intra/extrahepatic bile ducts, associates with a milder form of inflammatory bowel disease (IBD), particularly ulcerative colitis (UC). The pediatric PSC-IBD phenotype is less well characterized. METHODS: We performed a retrospective, single-center study examining patients with PSC-IBD at Texas Children's Hospital between 2000 and 2015. IBD-phenotype (Modified Montreal Classification), medications, laboratory values, endoscopic records, and IBD-based hospital admissions were collected. PSC-UC phenotype was compared to UC, non-PSC patients (n = 95) from Texas Children's Hospital. Elevated gamma-glutamyl transpeptidase levels were compared to calprotectin levels and IBD-flare activity, that is, gastrointestinal symptoms resulting in office/emergency department visits or hospital admission. RESULTS: Of 39 patients with PSC-IBD, 34 (87.2%) had UC (PSC-UC) and 5 (12.8%) had Crohn disease. Pancolitis was more common in PSC-UC than UC, non-PSC (96.3%, 64%, P = 0.0009). Patients with PSC-UC required less treatment with steroids (76.5%, 91.6%, P = 0.0326) or infliximab (8.8%, 37.9%, P = 0.0011), and fewer had at least 1 IBD-related hospital admission (32.4%, 63.2%, P = 0.0025) than UC, non-PSC. Progression to colectomy was significantly less (5.8%, 24.2%, P = 0.0223) in PSC-UC. Median diagnosis-to-colectomy time tended to be longer in PSC-UC (6.37, 2.5 years, P = 0.0792). In 2 smaller subsets, gamma-glutamyl transpeptidase did not correlate with calprotectin in PSC-UC (n = 11, P = 0.7922) and less strongly associated with IBD-flares in PSC-UC than UC, non-PSC (n = 33, n = 67; 15.2%, 41.8%, P = 0.0120). CONCLUSIONS: Pediatric PSC appears to associate with milder pancolitic-UC. PSC and IBD activity do not appear to correlate. Our findings may provide useful information toward etiology and management of pediatric PSC-IBD.

Allopurinol: a useful adjunct to thiopurine therapy for pediatric ulcerative colitis in the biologic era.

Thiopurines are used as a maintenance therapy in patients with ulcerative colitis (UC). For some patients the metabolism of thiopurines is unfavorable, leading to increased adverse effects, including hepatotoxicity. There are many reports in the adult literature concerning the manipulation of thiopurine metabolism with allopurinol; however, there is only 1 publication in this respect for pediatric UC. We present 3 pediatric cases of UC wherein the combination of allopurinol and low-dose 6-mercaptopurine allowed for shunting of thiopurine metabolites to a more favorable pattern. This intervention supported clinical remission in all, including one case poorly responsive to infliximab.

National Trends in Hospitalization, Surgical Resection, and Comorbidities in Pediatric Inflammatory Bowel Disease in the United States, 2002-2015.

Background and Objective: Therapeutic options for pediatric inflammatory bowel disease (PIBD) have dramatically changed over the last 20 years. However, the impact of modern medical management on PIBD outcomes remains unclear. We aimed to fill this gap in the literature by using a large, validated, national database, to study the change in hospitalization rates, surgical rates, and postoperative complications in PIBD over the last decade. Methods: The National Inpatient Sample (NIS) Database and ICD-9-CM codes were utilized to identify inpatient admissions with a primary or secondary diagnosis of pediatric Crohn's disease (CD) or ulcerative colitis (UC) from 2002-2015. Trends in hospitalizations, comorbidities (including malnutrition and weight loss), surgical procedures, and postoperative complications were examined using joinpoint regression analysis, a statistical modeling approach to evaluate the extent to which the rate of a condition changes over time. Results: There were 119,282 admissions for PIBD during the study period. The annual incidence of hospitalization increased significantly over time for both CD (average annual percent change [AAPC] 6.0%) and UC (AAPC 7.2%). The rate of intestinal resection decreased in CD patients (AAPC -6.4%) while postoperative complications remained unchanged. However, comorbidities increased significantly in CD patients (AAPC 6.8%). For pediatric UC patients, postoperative complications (AAPC 6.7%), and comorbidities (AAPC 10.2%) increased significantly over time while intestinal resection rates remained stable. Intestinal resection rate in pediatric CD has decreased over time, but not in pediatric UC. Conclusion and Global Health Implications: Annual incidence of hospitalization and comorbidities continue to increase in PIBD. Intestinal resection rate in pediatric CD has decreased over time, but not in pediatric UC. Our findings emphasize the critical need for prevention and novel therapeutic options for this vulnerable patient population.

Bacteroides ovatus colonization influences the abundance of intestinal short chain fatty acids and neurotransmitters.

Gut microbes can synthesize multiple neuro-active metabolites. We profiled neuro-active compounds produced by the gut commensal Bacteroides ovatus in vitro and in vivo by LC-MS/MS. We found that B. ovatus generates acetic acid, propionic acid, isobutyric acid, and isovaleric acid. In vitro, B. ovatus consumed tryptophan and glutamate and synthesized the neuro-active compounds glutamine and GABA. Consistent with our LC-MS/MS-based in vitro data, we observed elevated levels of acetic acid, propionic acid, isobutyric acid, and isovaleric acid in the intestines of B. ovatus mono-associated mice compared with germ-free controls. B. ovatus mono-association also increased the concentrations of intestinal GABA and decreased the concentrations of tryptophan and glutamine compared with germ-free controls. Computational network analysis revealed unique links between SCFAs, neuro-active compounds, and colonization status. These results highlight connections between microbial colonization and intestinal neurotransmitter concentrations, suggesting that B. ovatus selectively influences the presence of intestinal neurotransmitters.

Immunomodulation of dendritic cells by Lactobacillus reuteri surface components and metabolites.

BACKGROUND: Lactic acid bacteria are commensal members of the gut microbiota and are postulated to promote host health. Secreted factors and cell surface components from Lactobacillus species have been shown to modulate the host immune system. However, the precise role of L. reuteri secreted factors and surface proteins in influencing dendritic cells (DCs) remains uncharacterized. HYPOTHESIS: We hypothesize that L. reuteri secreted factors will promote DC maturation, skewing cells toward an anti-inflammatory phenotype. In acute colitis, we speculate that L. reuteri promotes IL-10 and dampens pro-inflammatory cytokine production, thereby improving colitis. METHODS & RESULTS: Mouse bone marrow-derived DCs were differentiated into immature dendritic cells (iDCs) via IL-4 and GM-CSF stimulation. iDCs exposed to L. reuteri secreted factors or UV-irradiated bacteria exhibited greater expression of DC maturation markers CD83 and CD86 by flow cytometry. Additionally, L. reuteri stimulated DCs exhibited phenotypic maturation as denoted by cytokine production, including anti-inflammatory IL-10. Using mouse colonic organoids, we found that the microinjection of L. reuteri secreted metabolites and UV-irradiated bacteria was able to promote IL-10 production by DCs, indicating potential epithelial-immune cross-talk. In a TNBS-model of acute colitis, L. reuteri administration significantly improved histological scoring, colonic cytokine mRNA, serum cytokines, and bolstered IL-10 production. CONCLUSIONS: Overall these data demonstrate that both L. reuteri secreted factors and its bacterial components are able to promote DC maturation. This work points to the specific role of L. reuteri in modulating intestinal DCs. NEW & NOTEWORTHY: Lactobacillus reuteri colonizes the mammalian gastrointestinal tract and exerts beneficial effects on host health. However, the mechanisms behind these effects have not been fully explored. In this article, we identified that L. reuteri ATTC PTA 6475 metabolites and surface components promote dendritic cell maturation and IL-10 production. In acute colitis, we also demonstrate that L. reuteri can promote IL-10 and suppress inflammation. These findings may represent a crucial mechanism for maintaining intestinal immune homeostasis.

Unraveling the Metabolic Requirements of the Gut Commensal Bacteroides ovatus.

Background: Bacteroidetes are the most common bacterial phylum in the mammalian intestine and the effects of several Bacteroides spp. on multiple facets of host physiology have been previously described. Of the Bacteroides spp., Bacteroides ovatus has recently garnered attention due to its beneficial effects in the context of intestinal inflammation. In this study, we aimed to examine model host intestinal physiological conditions and dietary modifications to characterize their effects on B. ovatus growth. Methods and Results: Using Biolog phenotypic microarrays, we evaluated 62 primary carbon sources and determined that B. ovatus ATCC 8384 can use the following carbohydrates as primary carbon sources: 10 disaccharides, 4 trisaccharides, 4 polysaccharides, 4 polymers, 3 L-linked sugars, 6 D-linked sugars, 5 amino-sugars, 6 alcohol sugars, and 15 organic acids. Proteomic profiling of B. ovatus bacteria revealed that a significant portion of the B. ovatus proteome contains proteins important for metabolism. Among the proteins, we found glycosyl hydrolase (GH) familes GH2, GH5, GH20, GH 43, GH88, GH92, and GH95. We also identified multiple proteins with antioxidant properties and reasoned that these proteins may support B. ovatus growth in the GI tract. Upon further testing, we showed that B. ovatus grew robustly in various pH, osmolarity, bile, ethanol, and H2O2 concentrations; indicating that B. ovatus is a well-adapted gut microbe. Conclusion: Taken together, we have demonstrated that key host and diet-derived changes in the intestinal environment influence B. ovatus growth. These data provide the framework for future work toward understanding how diet and lifestyle interventions may promote a beneficial environment for B. ovatus growth.

Human-Derived Bifidobacterium dentium Modulates the Mammalian Serotonergic System and Gut-Brain Axis.

BACKGROUND & AIMS: The human gut microbiota can regulate production of serotonin (5-hydroxytryptamine [5-HT]) from enterochromaffin cells. However, the mechanisms underlying microbial-induced serotonin signaling are not well understood. METHODS: Adult germ-free mice were treated with sterile media, live Bifidobacterium dentium, heat-killed B dentium, or live Bacteroides ovatus. Mouse and human enteroids were used to assess the effects of B dentium metabolites on 5-HT release from enterochromaffin cells. In vitro and in vivo short-chain fatty acids and 5-HT levels were assessed by mass spectrometry. Expression of tryptophan hydroxylase, short-chain fatty acid receptor free fatty acid receptor 2, 5-HT receptors, and the 5-HT re-uptake transporter (serotonin transporter) were assessed by quantitative polymerase chain reaction and immunostaining. RNA in situ hybridization assessed 5-HT-receptor expression in the brain, and 5-HT-receptor-dependent behavior was evaluated using the marble burying test. RESULTS: B dentium mono-associated mice showed increased fecal acetate. This finding corresponded with increased intestinal 5-HT concentrations and increased expression of 5-HT receptors 2a, 4, and serotonin transporter. These effects were absent in B ovatus-treated mice. Application of acetate and B dentium-secreted products stimulated 5-HT release in mouse and human enteroids. In situ hybridization of brain tissue also showed significantly increased hippocampal expression of 5-HT-receptor 2a in B dentium-treated mice relative to germ-free controls. Functionally, B dentium colonization normalized species-typical repetitive and anxiety-like behaviors previously shown to be linked to 5-HT-receptor 2a. CONCLUSIONS: These data suggest that B dentium, and the bacterial metabolite acetate, are capable of regulating key components of the serotonergic system in multiple host tissues, and are associated with a functional change in adult behavior.

Progression to colectomy in the era of biologics: A single center experience with pediatric ulcerative colitis.

BACKGROUND/PURPOSE: Clinical outcomes in pediatric ulcerative colitis (UC) in the era of biologic agents are poorly defined. We aimed to describe risk factors for colectomy in pediatric UC in the era of infliximab therapy. METHODS: We reviewed 217 pediatric patients at Texas Children's Hospital with newly diagnosed UC between 2003 and 2015; 117 had a minimum of 5 years of follow-up. Extent of disease at diagnosis, medication exposure, the presence of extraintestinal manifestations (EIMs), and need for surgery were noted. RESULTS: Average length of follow up was 5.02 ±â€¯2.27 years. Forty-two percent presented with pancolitis. Infliximab was used in 39%, immunomodulators in 65%, and steroids in 89% of patients. EIMs occurred in 24.9% of patients. The cumulative rate of colectomy was 12.9% at 5 years. Children presenting as E2 (Paris Classification) and children prescribed oral steroid monotherapy at diagnosis progressed to surgery faster than any other group. Of the children who received infliximab, females and children less than 5 years old were less likely to respond to therapy. CONCLUSIONS: The natural course of pediatric UC remains aggressive despite the addition of infliximab to the standard of care and suggests a need for early aggressive clinical intervention. LEVEL-OF-EVIDENCE RATING: Level IV.

Bacteroides ovatus ATCC 8483 monotherapy is superior to traditional fecal transplant and multi-strain bacteriotherapy in a murine colitis model.

Background and aims: Bacteriotherapy aimed at addressing dysbiosis may be therapeutic for Inflammatory Bowel Diseases (IBDs). We sought to determine if defined Bacteroides-based bacteriotherapy could be an effective and consistent alternative to fecal microbiota transplantation (FMT) in a murine model of IBD. Methods: We induced experimental colitis in 8- 12-week-old C57BL/6 mice using 2-3% dextran sodium sulfate. Mice were simultaneously treated by oral gavage with a triple-Bacteroides cocktail, individual Bacteroides strains, FMT using stool from healthy donor mice, or their own stool as a control. Survival, weight loss and markers of inflammation (histology, serum amyloid A, cytokine production) were correlated to 16S rRNA gene profiling of fecal and mucosal microbiomes. Results: Triple-Bacteroides combination therapy was more protective against weight loss and mortality than traditional FMT therapy. B. ovatus ATCC8483 was more effective than any individual strain, or a combination of strains, in preventing weight loss, decreasing histological damage, dampening inflammatory response, and stimulating epithelial recovery. Irrespective of the treatment group, overall Bacteroides abundance associated with treatment success and decreased cytokine production while the presence of Akkermansia correlated with treatment failure. However, the therapeutic benefit associated with high Bacteroides abundance was negated in the presence of Streptococcus. Conclusions: Bacteroides ovatus monotherapy was more consistent and effective than traditional FMT at ameliorating colitis and stimulating epithelial recovery in a murine model of IBD. Given the tolerability of Bacteroides ovatus ATCC 8483 in an active, on-going human study, this therapy may be repurposed for the management of IBD in a clinically expedient timeline.

Development of the Pediatric Gut Microbiome: Impact on Health and Disease.

The intestinal microbiota are important in human growth and development. Microbial composition may yield insights into the temporal development of microbial communities and vulnerabilities to disorders of microbial ecology such as recurrent Clostridium difficile infection. Discoveries of key microbiome features of carbohydrate and amino acid metabolism are lending new insights into possible therapies or preventative strategies for inflammatory bowel disease (IBD) and irritable bowel syndrome (IBS). In this review, we summarize the current understanding of the development of the pediatric gastrointestinal microbiome, the influence of the microbiome on the developing brain through the gut-brain axis, and the impact of dysbiosis on disease development. Dysbiosis is explored in the context of pediatric allergy and asthma, recurrent C. difficile infection, IBD, IBS, and metabolic disorders. The central premise is that the human intestinal microbiome plays a vital role in health and disease, beginning in the prenatal period and extending throughout childhood.

Inflammatory Bowel Disease and Immune Thrombocytopenic Purpura: Combined Immune Dysregulation in an Adolescent.

Concomitant inflammatory bowel disease (IBD) and immune thrombocytopenic purpura (ITP) is a rare phenomenon. A shared immunologic pathway leading to mucosal inflammation and platelet destruction has been proposed. We report a case of a 14-year-old male who presented with abdominal pain, hematochezia, weight loss, and thrombocytopenia. Endoscopic and hematologic evaluations led to the diagnosis of ulcerative colitis (UC) and ITP, respectively. Initial treatment of his UC resulted in improvement in both gastrointestinal symptoms and platelet count. Management of this case, however, was complicated by inconsistent correlation between UC symptoms and platelet count throughout his clinical course. The co-occurrence of IBD and ITP is an important entity, albeit rare, which needs to be considered when evaluating a patient with hematochezia and thrombocytopenia.

Diagnostic Yield of Routine Enteropathogenic Stool Tests in Pediatric Ulcerative Colitis.

GOALS: It can be important to exclude infectious etiologies prior to adjusting immunosuppressive therapy in patients with ulcerative colitis (UC) exacerbation. We sought to determine the diagnostic yield of routine infectious stool studies in pediatric UC patients. PROCEDURES: We conducted a retrospective review of 152 pediatric UC patients at Texas Children's Hospital between January 2003 and December 2009. The patient records were followed through July 2014. The number and type of infectious stool studies performed and the results of those were collected. RESULTS: Three hundred fifty-four diagnostic stool tests were conducted for Clostridium difficile; 13.6% were positive. Two hundred twenty stool bacterial cultures were performed, and 1.8% were positive, all growing non-typhoid Salmonella. One of 13 (7.7%) Adenovirus PCR tests was positive. Two of 152 examinations (1.3%) for Ova and Parasites were positive. No stool tests for viral culture, viral particles, Yersinia or Rotavirus were positive. CONCLUSIONS: Clostridium difficile infection is common in pediatric UC, and routine screening during flares is strongly recommended. Other bacterial and parasitic infections routinely tested for are uncommon, but Salmonella may be a potentially important attribute to disease exacerbations in select patients. In patients without co-morbid conditions, the utility of performing non-specific fecal viral tests is questionable.