Molecular characterization of the bacteria adherent to human colorectal mucosa.

AIMS: To study large intestinal mucosal bacterial communities by Denaturing Gradient Gel Electrophoresis (DGGE) profiling and sequencing of 16S rRNA gene polymerase chain reaction (PCR) products amplified from DNA extracted from colorectal biopsies taken from healthy individuals. The specific aims were to determine how similar the mucosa-associated bacterial communities are within and between individuals and also to characterize the phylogenetic origin of isolated DGGE bands. METHODS AND RESULTS: Human colorectal biopsies were taken at routine colonoscopy from 33 patients with normal looking mucosa. The DNA was extracted directly from single biopsies and the bacterial 16S rDNA PCR amplified. The PCR products were profiled using DGGE to generate a fingerprint of the dominant members of the bacterial community associated with the biopsy. The reproducibility of this method was high (>98%). Washed and unwashed biopsies gave similar DGGE banding patterns (Median Similarity Coefficient - MSC 96%, InterQuartile Range - IQR 3.0%, n = 5). Adjacent biopsies sampled from the same patient using different forceps gave similar DGGE profiles (MSC 94%, n = 2). Two colorectal biopsies sampled at locations 2-5 cm apart, from each of 18 patients, resulted in very similar profiles (MSC 100%, IQR 2.8%). Biopsies sampled from different locations within the large intestine of the same patient also gave similar DGGE profiles (MSC 98% IQR 3.3%n = 6). Although all patients (n = 33) gave different DGGE profiles, some similarity (c. 34%) was observed between profiles obtained from 15 patients arbitrarily selected. 35 DGGE bands were excised and sequenced. Many were found to be most closely related to uncultured bacterial sequence entries in the Genbank database. Others belonged to typical gut bacterial genera including Bacteroides, Ruminococcus, Faecalibacterium and Clostridium. CONCLUSIONS: Bacterial communities adherent to colorectal mucosa within a normal patient show little variation; in contrast, mucosal bacterial communities sampled from different patients with normal colorectal mucosa show a high degree of variation. SIGNIFICANCE AND IMPACT OF THE STUDY: This research demonstrates that DGGE profiling of 16S rRNA gene PCR products amplified from DNA extracted directly from mucosal samples offers fresh insight into the bacterial communities that are adherent to colorectal mucosa. These findings are important with respect to further studies on the gastrointestinal tract in health and disease.

Serological markers (anti-Saccharomyces cerevisiae mannan antibodies and antineutrophil cytoplasmic antibodies) in inflammatory bowel disease: diagnostic utility and phenotypic correlation.

We have evaluated the utility of antineutrophil cytoplasmic antibodies and anti-Saccharomyces cerevisiae mannan antibodies for distinguishing Crohn's disease from ulcerative colitis and other diarrheal illnesses by evaluating sera from 396 patients. Sensitivity, specificity, and phenotypic correlations were investigated. The implications of our findings for implementing these tests in routine clinical testing are discussed.

Wireless capsule endoscopy: a comparison with push enteroscopy in patients with gastroscopy and colonoscopy negative gastrointestinal bleeding.

BACKGROUND: The development of wireless capsule endoscopy allows painless imaging of the small intestine. Its clinical use is not yet defined. The aim of this study was to compare the clinical efficacy and technical performance of capsule endoscopy and push enteroscopy in a series of 50 patients with colonoscopy and gastroscopy negative gastrointestinal bleeding. METHODS: A wireless capsule endoscope was used containing a CMOS colour video imager, transmitter, and batteries. Approximately 50,000 transmitted images are received by eight abdominal aerials and stored on a portable solid state recorder, which is carried on a belt. Push enteroscopy was performed using a 240 cm Olympus video enteroscope. RESULTS: Studies in 14 healthy volunteers gave information on normal anatomical appearances and preparation. In 50 patients with gastrointestinal bleeding and negative colonoscopy and gastroscopy, push enteroscopy was compared with capsule endoscopy. A bleeding source was discovered in the small intestine in 34 of 50 patients (68%). These included angiodysplasia (16), focal fresh bleeding (eight), apthous ulceration suggestive of Crohn's disease (three), tumour (two), Meckel's diverticulum (two), ileal ulcer (one), jejunitis (one), and ulcer due to intussusception (one). One additional intestinal diagnosis was made by enteroscopy. The yield of push enteroscopy in evaluating obscure bleeding was 32% (16/50). The capsule identified significantly more small intestinal bleeding sources than push enteroscopy (p<0.05). Patients preferred capsule endoscopy to push enteroscopy (p<0.001). CONCLUSIONS: In this study capsule endoscopy was superior to push enteroscopy in the diagnosis of recurrent bleeding in patients who had a negative gastroscopy and colonoscopy. It was safe and well tolerated.

Wireless capsule endoscopic detection of Meckel's diverticulum after nondiagnostic surgery.

A patient aged 26 was investigated for recurrent severe gastrointestinal bleeding. Over a 4-year period, he was transfused more than 400 units of blood. Multiple investigations included three negative Meckel's scans. A right hemicolectomy for supposed angiodysplasia failed to control his bleeding. Wireless capsule endoscopy demonstrated the presence of a Meckel's diverticulum. At a repeat laparotomy, the ulcerated Meckel's diverticulum was identified and resected. The patient had no further bleeding and had a normal haemoglobin level on repeat blood tests up to 12 months after surgical excision of the diverticulum.