Alessia Cazzato

Bacillus subtilis isolated from the human gastrointestinal tract

As part of an ongoing study to determine the true habitat of Bacillus species, we report here the isolation and characterisation of Bacillus subtilis from the human gastrointestinal tract (GIT). Strains were obtained from ileum biopsies as well as from faecal samples and their biotypes defined. 16S rRNA analysis revealed that most isolates of B. subtilis were highly conserved, in contrast to RAPD-PCR fingerprinting that showed greater diversity with 23 distinct RAPD types. The majority of B. subtilis strains examined possessed features that could be advantageous to survival within the GIT. This included the ability to form biofilms, to sporulate anaerobically and secretion of antimicrobials. At least one isolate was shown to form spores that carried an exosporium, a loosely attached outer layer to the mature endospore, this being the first report of B. subtilis spores carrying an exosporium. This study reinforces a growing view that B. subtilis and probably other species have adapted to life within the GIT and should be considered gut commensals rather than solely soil microorganisms.

High efficacy of 1‐week doxycycline‐ and amoxicillin‐based quadruple regimen in a culture‐guided, third‐line treatment approach for Helicobacter pylori infection

Background : Helicobacter pylori infection may persist after both first‐ and second‐line current treatments.

Intestinal microbiota and its functions

Abstract The digestive tract harbours the largest and most complex microbial community of the human body, the intestinal microbiota, including about 800 different bacteria species. The distribution of this microflora is uneven, with highest concentrations in the colon. Bacterial colonization of human gut by environmental microbes, beginning immediately after birth, becomes more complex with increasing age, with a high degree of variability among human individuals. The gastrointestinal tract is the main site where environmental microorganisms and antigens interact with the host, through intensive cross-talks. Gut microbiota is essential for intestinal development, homeostasis and protection against pathogenic challenge; moreover, gut microbes are involved in metabolic reactions, with harvest of energy ingested but not digested by the host; they have also trophic effects on the intestinal epithelium, by favouring the development of intestinal microvilli, and play a fundamental role in the maturation of the hosts innate and adaptive immune responses.

Role of Probiotics in Patients with Helicobacter pylori Infection

Probiotics are defined as live, nonpathogenic microbial feeds or food supplements that exert a positive influence on their host by altering his microbial balance. As shown in several studies, probiotics also possess a direct antimicrobial effect; for this reason, several authors have tested a possible application in patients with Helicobacter pylori infection. In particular, probiotics may compete directly with H. pylori, possibly through the inhibition of adherence, as well as produce metabolites and antimicrobial molecules, properties supported only by animal or in vitro data. Moreover, implementation of standard anti‐H. pylori regimens with probiotics can also improve patients’ compliance to therapy, reducing the occurrence of antibiotic‐related adverse events. The same effect was also reported after using a combination of two different prebiotics such as butyric acid and inulin in patients who underwent H. pylori eradication treatment. Based on current data, even though an effect against H. pylori has been described, probiotics cannot be considered as an alternative to standard anti‐H. pylori treatment. Nevertheless, their use in association with standard anti‐H. pylori treatment may be advisable, as they are able to improve patient compliance by reducing antibiotic‐related adverse events, thus increasing the number of patients completing the eradication therapy.

Role of the immersion technique in diagnosing celiac disease with villous atrophy limited to the duodenal bulb

Goals To investigate if the so-called immersion technique during upper endoscopy may be helpful to predict patterns of villous atrophy restricted to the duodenal bulb. Background Patients with celiac disease may have a patchy distribution of duodenal villous atrophy. In some cases, mucosa of duodenal bulb may be the only intestinal area involved. The immersion technique is a novel procedure that allows visualizing duodenal villi directly during endoscopy. Study With this prospective study, the immersion duodenoscopy was performed in 67 celiac subjects to investigate their duodenal villous pattern. Villi were evaluated both in the first and in the second duodenal segment and judged as present or absent (flat mucosa). Results were compared with histology as reference. Results Among celiac subjects, 49 were newly diagnosed and 18 previously diagnosed celiac patients. Four (8%) newly diagnosed and 7 (39%) previously diagnosed celiac subjects had an extension of the villous atrophy (flat mucosa) limited to the duodenal bulb. The sensitivity, specificity, and positive and negative predictive values of the immersion-based duodenal investigation in predicting areas of duodenal villous atrophy was always 100%. Conclusions Immersion technique may be useful for directing duodenal biopsies in celiac subjects with a patchy distribution of villous atrophy. This procedure can avoid blinded sampling of the duodenal mucosa and enhance the diagnostic yield.

Water-immersion technique during standard upper endoscopy may be useful to drive the biopsy sampling of duodenal mucosa in children with celiac disease.

Objective: To evaluate the accuracy of the water-immersion technique during upper endoscopy in recognizing the duodenal villous pattern in a series of children who were undergoing endoscopy to obtain duodenal biopsy for histological analysis. Materials and Methods: The water-immersion technique was performed in 19 children. Endoscopic findings were compared with histology. Results were assessed on per biopsy analysis and per patient analysis, taking into account the worst endoscopic finding in each patient and correlating it with the worst histological diagnosis. Results: Per biopsy analysis: A total of 57 biopsy specimens were obtained and assessed. The endoscopic duodenal investigation correctly identified 53 areas (93%), which corresponded to histology, giving it an accuracy rate of 93%. Per patient analysis: The worst histology of the duodenal bulb was predicted by endoscopy in 18 of the 19 enrolled patients (95%), whereas the worst histopathological lesion of the second portion of the duodenum was recognized in 100% of cases. On the whole, therefore, the endoscopist suggested a diagnosis of celiac disease in 11 patients, with both positive and negative predictive values of 100%. Conclusions: The water-immersion technique during upper endoscopy is highly accurate in recognizing the duodenal villous pattern in subjects who need a duodenal investigation. Our findings encourage a cost-saving and patient-retaining approach to the diagnosis of celiac disease by driving biopsy and reducing the number of duodenal samplings.

The water immersion technique is easy to learn for routine use during EGD for duodenal villous evaluation: a single-center 2-year experience.

Goals We investigated the learning parameters of the immersion technique for the assessment of marked villous atrophy (MVA), during routine esophagogastroduodenoscopy (EGD). Background The immersion technique offers a proven possibility of enhancing the sensitivity of endoscopy in detecting duodenal villous atrophy patterns. Study Nine endoscopists with at least 2 years of experience, who had previously been trained to perform the immersion technique, searched for duodenal villi during routine EGD. In a 2-year study, duodenal villi were evaluated underwater duodenoscopy in 432 patients from whom duodenal biopsies had been, for various reasons, obtained. The endoscopic findings were compared with the histology. The learning parameters of the water immersion technique and the accuracy in detecting subjects with MVA were observed. Results A total of 28 (6.5%) patients with MVA were identified during endoscopy by the trained endoscopists. All these patients were diagnosed as being celiac patients. The sensitivity, specificity, and accuracy (positive and negative predictive values) of the immersion technique in detecting MVA patterns, irrespective of the endoscopist who performed the examination, were always 100%. Conclusions The underwater evaluation of the duodenum can be efficiently and regularly performed during routine EGD by endoscopists with 2 years of experience, after a specific, brief training period. This procedure is simple, feasible, and can accurately detect MVA patterns.

Malabsorption in psoriatic patients: cause or consequence?

Objective. The aetiopathogenesis of psoriasis is still unclear. Associations between gut and skin diseases are well known, since psoriatic patients show a high prevalence of coeliac disease. Small-bowel abnormalities can cause clinical or, more frequently, laboratory alterations that give rise to malabsorption. The aim of the study was to evaluate the prevalence of malabsorption in psoriatic patients. Material and methods. Fifty-five (29 M, 26 F, mean age 51±8 years) psoriatic patients in the Dermatology Centre of our hospital and 65 healthy controls (36 M, 29 F, mean age 47±9 years) were screened for malabsorption using a D-xylose test. Psoriatic subjects who resulted positive were further investigated in order to reach a better characterization of the malabsorption using serum antigliadin, antiendomysium and anti-transglutaminase antibodies, H2 lactulose breath test, the parasitological faecal test and colonoscopy with retrograde ileoscopy. Results. Altered D-xylose absorption was found in 60% (33/55) of psoriatic patients and in 3% (2/65) of controls. Of the former, 6% had coeliac disease, 21% had bacterial overgrowth, 3% had parasitic infections and 1 patient presented eosinophilic gastroenteritis. Conclusions. Malabsorption was more prevalent among psoriatic patients than among controls. Coeliac disease, bacterial overgrowth, parasitic infestations and eosinophilic gastroenteritis could be possible causes of malabsorption in these patients. Further studies are needed to clarify the pathogenesis and possible causative associations between gut and skin diseases.

Rifaximin-Based Regimens for Eradication of Helicobacter pylori: A Pilot Study

Background: Triple therapy is the treatment of choice for Helicobacter pylori-infected patients with an eradication rate ranging from 70 to 85%. Poor compliance and antibiotic resistance are the main causes of treatment failure. The aim of the present study was to assess the efficacy of rifaximin, a poorly absorbed antibiotic, for H. pylori eradication. Methods: We enrolled 48 consecutive H. pylori-positive patients affected. They were randomized to receive two 7-day rifaximin-based triple therapies: rifaximin tablets 400 mg t.i.d., esomeprazole 40 mg o.d. and clarithromycin 500 mg b.i.d. (CRE) or levofloxacin 500 mg o.d. (LRE). H. pylori eradication was assessed using a 13C-urea breath test 4 weeks after the end of therapy. Treatment compliance and the incidence of side effects were also evaluated. Results: No dropouts were observed. The eradication rate both on intention-to-treat and per-protocol analysis did not show significant differences between groups: 58% (14/24 patients) in group 1 and 42% (10/24 patients) in group 2 (p = 0.24, OR 1.96, 95% CI 0.62–6.18). No significant differences in patients’ compliance and incidence of side effects were found between groups. Conclusions: Rifaximin-based therapy showed optimal compliance but a limited eradication rate compared to standard first-line treatment. Further investigations are needed to evaluate different dosages and combinations.

Small intestinal bacterial overgrowth and intestinal permeability

The gastrointestinal tract is characterized by selective and dynamic permeability allowing the passage of nutrients and fluids and preventing the penetration of intruders such as microorganisms, toxins and other luminal antigens. The gut barrier integrity is essential to maintain human health and homeostasis. A derangement of intestinal permeability (IP) seems to be involved in the pathogenesis of several intestinal and systemic disorders [1]. Several structures including mucous coat, secretory IgA, epithelial layer, intercellular tight junctions, gut immune system and gut microflora contribute to maintain the integrity of such barrier. Small intestinal bacterial overgrowth (SIBO) is a common clinical condition due to an increase in the level of microorganisms to >10 colony forming units/ml of intestinal aspirate and/or of colonictype bacteria within the small intestine. This abnormally high bacterial population could affect intestinal barrier through a direct bacterial injury or an immune system activation resulting in the release of several inflammatory mediators and cytokines [2]. Aim of this study was to assess IP in patients with SIBO and the effect of SIBO decontamination. Twenty patients affected by SIBO as assessed by hydrogen glucose breath test (GBT) (mean age 46.3 ± 7.8 years, M/F 9/11) and 21 controls without SIBO (mean age 45.1 ± 8.1 years, M/F 9/12) were enrolled after written informed consent. The test was considered as an indicative of SIBO when the peak, that is the increase over baseline hydrogen levels, was > 12 parts per million [3]. Exclusion criteria were all factors known to impair IP: gastrointestinal disorders and infections, use of non-steroidal antiinflammatory and immunosuppressive drugs, alcohol consumption, allergic diseases and HIV infection. Chromium ethylene-diamine-tetra-acetate (CrEDTA) absorption test was performed in all patients to assess IP. The test methodology was the same as described in a previous study by our group [4]. The 24-h urinary excretion of Cr-EDTA was expressed as a fraction of the oral administered dose and considered abnormal if ‡ 3% [4]. All patients were treated by rifaximin (Normix 200 mg tablets, Alfa-Wassermann) 1200 mg per day (2 tablets t.i.d.) for 7 days [5] and underwent GBT and Cr-EDTA absorption test 4 weeks after the end of the therapy. An IP derangement was observed in 11 out of 20 SIBO patients (55%, mean Cr-EDTA urinary excretion rate: 3.47 ± 0.30) compared to 1 out of 21 controls (4.8%, mean Cr-EDTA urinary excretion rate: 2.17 ± 0.16; p = 0.002). Among SIBO patients with deranged IP, IP normalized in 6 out of 8 successfully decontaminated (75%) compared to 2 out of 3 non-decontaminated patients (66%, p = ns). The mean Cr-EDTA urinary excretion rate significantly decreased after successful decontamination (2.28 ± 0.38 vs. 3.7 ± 0.58, ANOVA p < 0.005).