Alterations in the colonic microbiota in response to osmotic diarrhea.

BACKGROUND & AIMS: Diseases of the human gastrointestinal (GI) tract are often accompanied by diarrhea with profound alterations in the GI microbiota termed dysbiosis. Whether dysbiosis is due to the disease itself or to the accompanying diarrhea remains elusive. With this study we characterized the net effects of osmotic diarrhea on the composition of the GI microbiota in the absence of disease. METHODS: We induced osmotic diarrhea in four healthy adults by oral administration of polyethylene glycol 4000 (PEG). Stool as well as mucosa specimens were collected before, during and after diarrhea and 16S rDNA-based microbial community profiling was used to assess the microbial community structure. RESULTS: Stool and mucosal microbiotas were strikingly different, with Firmicutes dominating the mucosa and Bacteroidetes the stools. Osmotic diarrhea decreased phylotype richness and showed a strong tendency to equalize the otherwise individualized microbiotas on the mucosa. Moreover, diarrhea led to significant relative shifts in the phyla Bacteroidetes and Firmicutes and to a relative increase in the abundance of Proteobacteria on the mucosa, a phenomenon also noted in several inflammatory and diarrheal GI diseases. CONCLUSIONS: Changes in microbial community structure induced by osmotic diarrhea are profound and show similarities to changes observed in other GI diseases including IBD. These effects so must be considered when specimens from diarrheal diseases (i.e. obtained by stratification of samples according to diarrheal status) or conditions wherein bowel preparations like PEG (i.e. specimens obtained during endoscopy) are used.

Cytotoxic effects of Klebsiella oxytoca strains isolated from patients with antibiotic-associated hemorrhagic colitis or other diseases caused by infections and from healthy subjects.

Antibiotic-associated hemorrhagic colitis (AAHC) is associated with Klebsiella oxytoca. This study analyzed whether cytotoxic properties are linked to specific subtypes of K. oxytoca. Klebsiella isolates from stools of AAHC patients, healthy carriers, and diarrhea patients as well as from infections of other organs were investigated. Cytotoxic effects on human epithelial cells were limited to the species K. oxytoca and were not detectable for any other Klebsiella species. Isolates from AAHC patients and from stools showed the highest proportion of cytotoxic strains. Urinary or respiratory tract isolates exhibited no cytotoxicity. Macrorestriction profiling of strains revealed no genetic relationships of AAHC isolates or the cytotoxic phenotype but identified that different K. oxytoca strains with different cytotoxic behaviors may be prevalent in the same AAHC patient. Under laboratory conditions, cytotoxicity was maximally effective after exponential bacterial growth and then declined despite the continued viability of K. oxytoca cells in culture. Given its capacity to induce AAHC and that a high proportion of stool isolates tested cytotoxin positive, we argue that K. oxytoca should be considered an opportunistic pathogen if detected in stools. The ability to induce disease after antibiotic treatment most likely represents an overgrowth of the toxin-producing bacterium due to an alteration of the normal colonic microflora.

Role of Klebsiella oxytoca in antibiotic-associated diarrhea.

BACKGROUND: Klebsiella oxytoca was recently shown to be the causative agent of antibiotic-associated hemorrhagic colitis. Because it is unclear whether K. oxytoca also causes nonhemorrhagic antibiotic-associated diarrhea, our study investigated a possible association between K. oxytoca and that disorder. METHODS: A total of 371 consecutive patients were recruited into 4 study groups: (1) group A+D+ (patients who received antibiotics and experienced diarrhea; n = 107), (2) group A+D- (patients who received antibiotics but did not experience diarrhea; np93), (3) group A-D+ (patients who experienced acute-onset diarrhea but did not receive antibiotics; n = 60), and (4) group A-D- (patients without diarrhea who did not receive antibiotics; n = 111). Stool samples were plated on MacConkey agar and K. oxytoca was identified using a standard test kit. Clostridium difficile was detected by a toxin A/B antigen test. K. oxytoca strains were tested for cytotoxicity with use of cell-culture assays. RESULTS: In 15 of 371 stool samples, K. oxytoca strains were isolated during the study period. There was no significant difference in the distribution of K. oxytoca among the 4 study groups. Six of the 15 strains were found to be toxin producing. Three of the toxin-producing strains caused antibiotic-associated hemorrhagic colitis. No case of nonhemorrhagic antibiotic-associated diarrhea due to toxin-producing K. oxytoca was detected. CONCLUSION: K. oxytoca is not the causative agent of nonhemorrhagic antibiotic-associated diarrhea. This is in contrast to the distinct clinical entity of antibiotic-associated hemorrhagic colitis. Testing for K. oxytoca is therefore only warranted for patients who experience bloody diarrhea during antibiotic therapy.

Renal cell carcinoma metastatic to the stomach: single-centre experience and literature review.

OBJECTIVES: To investigate the incidence, clinical presentation and therapy of gastric metastases, an uncommon finding, in a large group of patients with renal cell carcinoma (RCC). PATIENTS AND METHODS: We systematically searched the computerized RCC database of our institute, covering 2082 patients (1180 men and 902 women) who had surgery between January 1984 and September 2005, to identify those with a synchronous and/or metachronous diagnosis of cancer in gastric biopsies or resection specimens. The histopathological slides of both renal and gastric cancer probes, and the clinical presentation, treatment and outcome of affected patients, were reassessed. RESULTS: Twelve patients with primary gastric cancer, one with local RCC recurrence affecting the antrum and five with clear cell RCC (three men and two women; mean age 73 years, range 65-83) with haematogenous cancer spread to the stomach were detected. The mean (range) time to gastric metastasis was 6.9 (1.7-13.1) years. There were metastases to other organs, most often the lung, in all patients. Three patients presented with symptoms of gastrointestinal bleeding, which was successfully controlled by local endoscopic therapy. Four patients died from disease at 3-19 months after diagnosis. One patient is still alive with disease after approximately 2 years. CONCLUSIONS: Gastric metastasis in patients with RCC appears to be a late event in the course of the disease. Most patients show concomitant tumour spread to other organs, and the outcome is generally poor. The use of targeted drugs might offer a new perspective for affected patients.

Juvenile polyposis of the stomach causing recurrent upper gastrointestinal bleeding.

We present the case of a 42-year-old man who suffered from recurrent severe upper gastrointestinal bleeding starting from February 2003. Endoscopy showed multiple glassy polyps in the stomach, which corresponded to a diffuse mucosal thickening detected by endosonography. The duodenum was normal. In February 2006, life-threatening acute gastrointestinal bleeding prompted total gastrectomy. The resection specimen showed the gastric mucosa carpeted by numerous glassy pedunculated polyps, measuring 2 cm in largest diameter. Histologically, the polyps were characterized by an abundant loose stroma and by elongated, twisting foveolae, covered by hyperplastic epithelium. Colonoscopy including the terminal ileum revealed a single tubulovillous adenoma, but no hamartomatous polyps, rendering a final diagnosis of juvenile polyposis of the stomach. This case represents the first description of juvenile polyposis causing life-threatening gastric haemorrhage. Thus, although rare, the disease has to be considered in the differential diagnosis of patients with acute upper gastrointestinal tract bleeding.

Klebsiella oxytoca as a causative organism of antibiotic-associated hemorrhagic colitis.

BACKGROUND: Antibiotic-associated hemorrhagic colitis is a distinct form of antibiotic-associated colitis in which Clostridium difficile is absent. Although the cause is not known, previous reports have suggested a role of Klebsiella oxytoca. METHODS: We studied 22 consecutive patients who had suspected antibiotic-associated colitis and who were negative for C. difficile. Patients underwent diagnostic colonoscopy, and among those who received a diagnosis of antibiotic-associated hemorrhagic colitis, stool samples were cultured for K. oxytoca. We isolated K. oxytoca strains and tested them for cytotoxin production using a tissue-culture assay. In addition, we also cultured stool samples obtained from 385 healthy subjects for K. oxytoca. An in vivo animal model for antibiotic-associated hemorrhagic colitis was established with the use of Sprague-Dawley rats. RESULTS: Of the 22 patients, 6 had findings on colonoscopy that were consistent with the diagnosis of antibiotic-associated hemorrhagic colitis, and 5 of these 6 patients had positive cultures for K. oxytoca. No other common enteric pathogens were found in the five patients. Before the onset of colitis, all five were receiving penicillins, and two were also taking nonsteroidal antiinflammatory drugs (NSAIDs). All isolated K. oxytoca strains produced cytotoxin. K. oxytoca was found in 1.6% of the healthy subjects. In the animal model, K. oxytoca was found only in the colon of rats that received amoxicillin-clavulanate in addition to being inoculated with K. oxytoca. In these rats, infection with K. oxytoca induced a right-sided hemorrhagic colitis that was not observed in uninfected animals that received amoxicillin-clavulanate, indomethacin (an NSAID), or both. CONCLUSIONS: Our fulfillment of Koch's postulates for cytotoxin-producing K. oxytoca suggests that it is the causative organism in at least some cases of antibiotic-associated hemorrhagic colitis. Infection with K. oxytoca should be considered in patients with antibiotic-associated colitis who are negative for C. difficile.

Critical evaluation of real-time reverse transcriptase-polymerase chain reaction for the quantitative detection of cytokeratin 20 mRNA in colorectal cancer patients.

We evaluated the usefulness of cytokeratin 20 (CK20) mRNA expression in the quantitative detection of circulating tumor cells in the blood of patients with colorectal cancer (CRC). Blood samples from healthy volunteers (HVs; n = 37), patients with localized (n = 42) and metastatic colorectal cancer (n = 40), and patients with chronic inflammatory bowel disease (CID; n = 15) were examined. After immunomagnetic enrichment using microbeads against human epithelial antigen, total RNA was extracted, reverse transcribed, and analyzed by real-time reverse transcriptase-polymerase chain reaction using the LightCycler instrument. CK20 expression in peripheral blood was found in 46 of 82 (56%) patients with CRC, 8 of 37 (22%) HVs, and 9 of 15 (60%) patients with CID. Levels of CK20 mRNA were significantly higher in blood samples from CRC patients (median 681) than in blood samples from HVs (median 0) (P = 0.001), whereas no difference could be detected between patients with CRC and CID. Although the present technique could not distinguish CRC from CID, the method warrants further efforts to improve sample preparation and tumor cell enrichment, which may render real-time CK20 reverse transcriptase-polymerase chain reaction a feasible technique in identifying circulating tumor cells in peripheral blood of cancer patients.

Complete remission of a metastatic gastrointestinal stromal tumour with the tyrosine kinase inhibitor imatinib (STI 571): effect of low dosage in an advanced tumour with exon 11 mutation.

We report a 51-year-old man with an advanced malignant metastatic gastrointestinal stromal tumour, who showed a complete response after 5 months of treatment with imatinib at a dose of 400 mg per day. An early treatment response was demonstrated in an 18fluorodeoxyglucose positron emission tomography scan after 1 month of therapy. Complete remission was documented histologically by negative serial biopsies of residual tumour nodes after 5 months of therapy. No serious side effects were seen with imatinib. A 21 bp, exon 11, in-frame mutation of the c-kit gene was found by DNA sequence analysis of tumour tissue.

Treatment of extranodal marginal zone B-cell lymphoma of mucosa-associated lymphoid tissue type with cladribine: a phase II study.

PURPOSE: As chemotherapy has not been extensively studied in patients with lymphoma of the mucosa-associated lymphoid tissue (MALT), we initiated a prospective study to evaluate the activity of the nucleoside analog cladribine (2-chlorodeoxyadenosine [2-CdA]) in this disease. PATIENTS AND METHODS: Patients with histologically verified MALT-type lymphoma were enrolled. 2-CdA was administered at a dose of 0.12 mg/kg body weight on 5 consecutive days, as a 2-hour infusion. Cycles were repeated every 4 weeks for a maximum of six cycles. RESULTS: Nineteen patients with gastric and seven patients with extragastric MALT lymphoma were enrolled. All patients were chemotherapy-naive, and two had been locally irradiated before systemic relapse of the lymphoma. A total of 102 cycles was administered to our patients (median number of cycles per patient, four). All 25 assessable patients responded to treatment: 21 patients (84%) achieved complete remission (CR) and four patients achieved partial remission. All patients (100%) with gastric presentation, but only three patients (43%) with extragastric presentation, achieved CR. Toxicities were moderate and mainly hematologic and required dose reduction and/or premature discontinuation of therapy in only three cases. Two patients died from vascular events, one shortly after the first cycle because of myocardial infarction and the other from stroke 3 months after the second course. Three patients relapsed after 13, 18, and 22 months and one patient showed progressive disease after 15 months. At present, 24 patients are alive at a median follow-up time of 32 months. CONCLUSION: Our data demonstrate that 2-CdA is highly effective in inducing CR in 84% of patients with MALT-type lymphoma.

Multiplanar spiral CT enterography in patients with Crohn's disease using a negative oral contrast material: initial results of a noninvasive imaging approach.

The aim of this study was to prospectively define the role of multiplanar spiral CT enterography with a new negative oral contrast material for noninvasive assessment of the small bowel in patients with Crohn's disease. Thirty patients with established Crohn's disease prospectively underwent spiral CT enterography at 45-60 min after distension of the small bowel with 1400 ml of a negative oral contrast material (Mucofalk water enema). Spiral CT scans were obtained 50 s after administration of intravenous contrast material with the following parameters: 5-mm collimation; 7.5-mm/s table feed; and 3-mm reconstruction interval. The adequacy of bowel opacification, luminal distension, and the contribution of two-dimensional multiplanar reformatted imaging were assessed by two observers. Spiral CT imaging findings were compared with results of enteroclysis as well as endoscopic and histological findings in all patients. Spiral CT enterography with Mucofalk water enema was well tolerated in 29 of 30 patients. Findings on spiral CT enterography were comparable with those of barium studies in 25 of 30 patients, superior to those on barium studies in 4 patients, and inferior in 1 patient ( p<0.05). The addition of multiplanar reformatted images to axial spiral CT scans significantly improved observers' confidence in image interpretation ( p<0.05) but did not reveal additional abnormalities. Multiplanar spiral CT enterography with Mucofalk excellently provides information in patients with Crohn's disease. This technique accurately depicts the level of small bowel obstruction and the extent of inflammatory small bowel disease and its extraluminal complications.