Production of Escherichia coli STa-like heat-stable enterotoxin by Citrobacter freundii isolated from humans.

Citrobacter species are often present in the stools of children and are generally considered a normal component of the intestinal microflora. Previous reports suggested that they might act as enteric pathogens. Aiming at defining the role of Citrobacter species in inducing diarrhea, we looked for their presence in the stools of 328 children with diarrhea and in 108 controls. Citrobacter strains were isolated from 46 patients (14%) and 7 controls (6.5%) (P less than 0.05). All isolates were tested for heat-stable (ST) and heat-labile (LT) enterotoxin. No LT-producing organisms were found. Three C. freundii strains, all isolated from children with diarrhea, elaborated an enterotoxin detected by the suckling mouse assay. A crude extract was prepared by acetone precipitation and a sequential ultrafiltration technique. The enterotoxin was heat stable, and its estimated molecular weight was between 2,000 and 10,000. Citrobacter enterotoxin was soluble in methanol and stable at acid and neutral pHs but not above pH 8, and its activity was destroyed by treatment with 2-mercaptoethanol. Citrobacter enterotoxin was inactive in the 18-h rabbit ileal loop test. All these characteristics closely resemble STa produced by Escherichia coli. The time course of Citrobacter enterotoxin-induced intestinal secretion in suckling mice was similar to that of E. coli STa. The enterotoxin produced by C. freundii cross-reacted with monoclonal antibodies raised against E. coli STa. These results suggest that C. freundii is capable of inducing diarrhea through the production of an E. coli-like STa, and its presence in the stools of patients with diarrhea should be considered as that of a possible etiologic agent

Lower Level of Plasma 25-Hydroxyvitamin D in Children at Diagnosis of Celiac Disease Compared with Healthy Subjects: A Case-Control Study

Objective: To evaluate the vitamin D status of children with a new diagnosis of celiac disease compared with healthy controls. Study design: This was a case-control study. Cases were consecutive children with newly diagnosed celiac disease. Controls were healthy children matched for age, sex, ethnicity, and month of blood testing. Plasma 25-hydroxyvitamin D (25-OHD) was measured as the index of vitamin D nutritional status. The Student t test was used for comparisons. Differences in frequencies were evaluated with the χ2 test. Associations between variables were estimated by calculating Pearson correlation coefficients. Results: There were 131 children with celiac disease enrolled (62% females; mean age 8.1 ± 1.1 years). The control group included 131 healthy children (62% females; mean age 8.2 ± 1.2). All were of European origin. Plasma 25-OHD levels were significantly lower in patients than in controls (25.3 ± 8.0 and 31.6 ± 13.7 ng/mL; P <.0001). The percentage of children with vitamin D deficiency (<20 ng/mL) was significantly higher in children with celiac diseaseas compared with controls (31% vs 12%; P <.0001). The concentration of 25-OHD was significantly lower in patients than in controls during summer (P <.01) and autumn (P <.0001). Conclusions: In this case-control study, at diagnosis, children with celiac disease showed lower levels of plasma 25-OHD compared with healthy subjects. Vitamin D status should be checked at diagnosis of celiac disease, particularly during summer and fall months

Misuse of serological screening tests for celiac disease in children: A prospective study in Italy

Background: Despite a well-established diagnostic algorithm for celiac disease, it remains unclear whether prescriptions for celiac serological tests comply with the current pediatric guidelines. Aim: To analyze the appropriateness of test prescription in children investigated for celiac disease in Italy, compared to the current European pediatric guidelines. Methods: All children who had performed a first evaluation for celiac disease were prospectively enrolled. Prescribed tests and related indications for testing were recorded, and compared to the European pediatric guidelines. Results: Overall, 202 children were enrolled (females 59%, mean age 7.1 years ±4.1) in two centers. The reasons for celiac disease testing were typical, atypical symptoms or celiac disease-associated conditions in 46.5%, 49%, and 4.5% of cases, respectively. First-line tests were IgA and IgG anti-transglutaminase antibodies in 88.1% and 29.7% of children, IgA and IgG anti-deamidated gliadin peptide antibodies in 43% and 47%, IgA and IgG anti native gliadin in 15.8%, IgA anti-endomysium antibodies in 44.5%, HLA predisposing genes in 10% of patients. Test redundancy was very common, and the current diagnostic guidelines were correctly followed only in 23/202 patients (11.4%). Conclusions: Diagnostic European guidelines for celiac disease screening are often disregarded in Italy. Intervention to implement adherence to these guidelines is needed, with the aim of improving resource utilization, and quality of patient care

Therapy with Gastric Acidity inhibitors increases the risk of acute gastroenteritis and pneumonia in children.

OBJECTIVE: Gastric acidity (GA) inhibitors, including histamine-2 receptor antagonists (H2 blockers) and proton pump inhibitors (PPIs), are the mainstay of gastroesophageal reflux disease (GERD) treatment. A prolonged GA inhibitor-induced hypochlorhydria has been suggested as a risk factor for severe gastrointestinal infections. In addition, a number of papers and a meta-analysis have shown an increased risk of pneumonia in H2-blocker-treated intensive care patients. More recently, an increased risk of community-acquired pneumonia associated with GA inhibitor treatment has been reported in a large cohort of adult patients. These findings are particularly relevant to pediatricians today because so many children receive some sort of GA-blocking agent to treat GERD. To test the hypothesis that GA suppression could be associated with an increased risk of acute gastroenteritis and pneumonia in children treated with GA inhibitors, we conducted a multicenter, prospective study. METHODS: The study was performed by expert pediatric gastroenterologists from 4 pediatric gastroenterology centers. Children (aged 4-36 months) consecutively referred for common GERD-related symptoms (for example, regurgitation and vomiting, feeding problems, effortless vomiting, choking), from December 2003 to March 2004, were considered eligible for the study. Exclusion criteria were a history of GA inhibitors therapy in the previous 4 months, Helicobacter pylori infection, diabetes, chronic lung or heart diseases, cystic fibrosis, immunodeficiency, food allergy, congenital motility gastrointestinal disorders, neuromuscular diseases, or malnutrition. Control subjects were recruited from healthy children visiting the centers for routine examinations. The diagnosis of GERD was confirmed in all patients by standard criteria. GA inhibitors (10 mg/kg ranitidine per day in 50 children or 1 mg/kg omeprazole per day in 50 children) were prescribed by the physicians for 2 months. All enrolled children were evaluated during a 4-month follow-up. The end point was the number of patients presenting with acute gastroenteritis or community-acquired pneumonia during a 4-month follow-up study period. RESULTS: We obtained data in 186 subjects: 95 healthy controls and 91 GA-inhibitor users (47 on ranitidine and 44 on omeprazole). The 2 groups were comparable for age, gender, weight, length, and incidence of acute gastroenteritis and pneumonia in the 4 months before enrollment. Rate of subjects presenting with acute gastroenteritis and community-acquired pneumonia was significantly increased in patients treated with GA inhibitors compared with healthy controls during the 4-month follow-up period. In the GA inhibitor-treated group, the rate of subjects presenting with acute gastroenteritis and community-acquired pneumonia was increased when comparing the 4 months before and after enrollment. No differences were observed between H2 blocker and PPI users in acute gastroenteritis and pneumonia incidence in the previous 4 months and during the follow-up period. On the contrary, in healthy controls, the incidence of acute gastroenteritis and pneumonia remained stable. CONCLUSIONS: This is the first prospective study performed in pediatric patients showing that the use of GA inhibitors was associated with an increased risk of acute gastroenteritis and community-acquired pneumonia in GERD-affected children. It could be interesting to underline that we observed an increased incidence of intestinal and respiratory infection in otherwise healthy children taking GA inhibitors for GERD treatment. On the contrary, the majority of the previous data showed that the patients most at risk for pneumonia were those with significant comorbid illnesses such as diabetes or immunodeficiency, and this points to the importance of GA suppression as a major risk factor for infections. In addition, this effect seems to be sustained even after the end of therapy. The results of our study are attributable to many factors, including direct inhibitory effect of GA inhibitors on leukocyte functions and qualitative and quantitative gastrointestinal microflora modification. Additional studies are necessary to investigate the mechanisms of the increased risk of infections in children treated with GA inhibitors, and prophylactic measures could be considered in preventing them

Pathogenesis of postantibiotic diarrhoea caused by Clostridium difficile: an in vitro study in the rabbit intestine.

To elucidate the pathophysiological changes leading to postantibiotic diarrhoea caused by Clostridium difficile and its cytotoxin, oral ampicillin was given to rabbits, and jejunal, ileal, and caecal segments of those that developed diarrhoea were investigated in vitro. The rabbits that, in response to treatment, harboured Clostridium difficile in their colonic lumen were studied, and the results expressed according to the presence or absence of Clostridium difficile and/or its cytotoxin. Thus, we refer to either CD+ or CD- segments. The influx of glucose, phenylalanine, glycylphenylalanine, and lysine across the brush border of jejunum and ileum of CD+ segments was severely impaired, while only slightly blunted in CD-. No significant change was detected in the influx of glutamic acid in the jejunum of all treated animals and in the CD- ilea. Morphologic damage in ileum and caecum of CD+ was also more evident than in CD-. Transepithelial ion transport across short circuited ileal mucosa (CD+ and CD-) revealed secretory changes in Cl net transport that were more marked in CD-. We conclude that: (1) Clostridium difficile may also colonise the upper intestinal tract, where it induces morphological and functional damage, severely impairing nutrient absorption; and (2) the ileum contributes to the diarrhoea caused by CD even when the micro-organism is confined to the more distal gut by showing moderate impairment of nutrient absorption and marked electrolyte secretion