Clinical and environmental Vibrio cholerae organisms collected from February 2004 through April 2005 were systematically isolated from 2 rural Bangladeshi locales. Their genetic relatedness was evaluated at 5 loci that contained a variable number of tandem repeats (VNTR). The observed minimal overlap in VNTR patterns between the 2 communities was consistent with sequential, small outbreaks from local sources.

By conventional genetic methods, including pulse‐field gel electrophoresis and multilocus sequence typing, most pathogenic, cholera toxin‐positive O1 and O139 isolates of Vibrio cholerae cannot be distinguished. We evaluated relationships among 173 V. cholerae isolates collected between 1992 and 2007 from different geographic areas in India by analyzing five variable number of tandem repeat (VNTR) loci. Each VNTR locus was highly variable, with between 5 and 19 alleles. eburst analysis revealed four large groups of genetically related isolates. Two groups contained genotypes of isolates with the O139 serogroup (which emerged for the first time in epidemic form in 1992), with the other two groups containing O1 strains. In subsequent analysis, it was possible to track the spread of specific genotypes across time and space. Our data highlight the utility of the methodology as an epidemiologic tool for assessing spread of isolates in both epidemic and endemic settings.

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O-antigen biosynthetic (wbf) regions for Vibrio cholerae serogroups O5, O8, and O108 were isolated and sequenced. Sequences were compared to those of other published V. cholerae O-antigen regions. These wbf regions showed a high degree of heterogeneity both in gene content and in gene order. Genes identified frequently showed greater similarities to polysaccharide biosynthesis genes from species other than V. cholerae. Our results demonstrate the plasticity of O-antigen genes in V. cholerae, the diversity of the genetic pool from which they are drawn, and the likelihood that new pandemic serogroups will emerge.Cholera is a pandemic diarrheal disease that continues to be an important cause of morbidity and mortality worldwide. Cholera is associated with a clonally related subset of Vibrio cholerae strains, which carry ctxAB (cholera toxin subunits A and B), the vibrio pathogenicity island (VPI), and other cholera-associated genes (15,40). Until 1992, only serogroup O1 (out of more than 206 serogroups currently described) was recognized as a cause of cholera. In 1992, a new, non-O1 V. cholerae strain (subsequently designated V. cholerae O139) appeared in India and rapidly spread across much of Asia (32). Extensive studies (5,12,31,41) demonstrated that the O139 strain was closely related to the O1 El Tor strains of the 7th pandemic, except that the genes responsible for O1-antigen biosynthesis were deleted and replaced with DNA that encodes the O139 antigen. Since the O antigen is the major protective epitope, its alteration was sufficient to allow O139 strains to move in epidemic form through populations previously immune to cholera caused by O1. Thus, adults were more commonly affected than children (1). Recent studies suggest that the pandemic cluster carries other serogroups as well, including O37, O27, O53, O65, and O75 (31, 40, 43). These observations are consistent with the hypothesis that pathogenic V. cholerae strains are able to easily acquire and/or exchange O-antigen genes, with the new O antigen allowing strains to evade preexisting immunity to cholera.Changes in O-antigen structure also may provide selective advantages in the environment. During epidemics, bacteriophage may play a crucial role in controlling the number of V. cholerae in the environment (19), and since the O-antigen may serve as bacteriophage receptors, serogroup conversion also may be beneficial for evading phage predation (33). It is well documented that mobile genetic elements, bacteriophage, and the competence of V. cholerae to take up and assimilate free DNA from the environment significantly contribute to genetic diversity in V. cholerae (18). Serogroup conversion was demonstrated while V. cholerae was growing on a chitin substrate (6). This transfer may have been facilitated by the JUMPstart sequence, which has nucleotide similarity to a DNA uptake signal that causes the preferential uptake of free DNA containing that sequence in the Pasteurellaceae and is present in front of a laterally transferred O-antigen region in V. chole...

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Background:The diagnosis and treatment of small-bowel diseases is clinically difficult. The purpose of this study was to evaluate the diagnostic and therapeutic value of double-balloon enteroscopy in small-bowel diseases.Methods:The history and outcomes of 2806 patients who underwent double-balloon enteroscopy from July 2004 to April 2017 were reviewed, which included 562 patients with obscure digestive tract bleeding, 457 patients with obscure diarrhea, 930 patients with obscure abdominal pain, 795 patients with obscure weight loss, and 62 patients with obscure intestinal obstruction. Examinations were performed through the mouth and/or anus according to the clinical symptoms and abdominal images. If a lesion was not detected through one direction, examination through the other direction was performed as necessary. Eighty-four patients with small-bowel polyps, 26 with intestinal obstruction caused by enterolith, and 18 with bleeding from Dieulafoy's lesions in the small intestine were treated endoscopically.Results:A total of 2806 patients underwent double-balloon enteroscopy, and no serious complications occurred. An endoscopic approach through both the mouth and anus was used in 212 patients. Lesions were detected in 1696 patients, with a detection rate of 60.4%; the rates for obscure digestive tract bleeding, diarrhea, abdominal pain, weight loss, and intestinal obstruction were 85.9% (483/562), 73.5% (336/457), 48.2% (448/930), 49.1% (390/795), and 62.9% (39/62), respectively. For patients with small-bowel polyps who underwent endoscopic therapy, no complications such as digestive tract bleeding and perforation occurred. Intestinal obstruction with enteroliths was relieved with endoscopic lithotripsy. Among the 18 patients with bleeding from small-bowel Dieulafoy's lesions, 14 patients were controlled with endoscopic hemostasis.Conclusion:Double-balloon enteroscopy is useful for diagnosing and treating some small-bowel disease.

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