The Toxin-Producing Pathobiont Klebsiella oxytoca Is Not Associated with Flares of Inflammatory Bowel Diseases.

<bold>Background: </bold>Alterations in the intestinal microbiota are thought to be involved in the pathogenesis of inflammatory bowel diseases (IBD). Klebsiella oxytoca is an intestinal pathobiont that can produce a cytotoxin (tillivaline).<bold>Aim: </bold>We aimed to elucidate the pathogenetic relevance of toxin-producing K. oxytoca in patients with IBD flares and investigated the clonal relationship of K. oxytoca isolates from IBD patients using multilocus sequence typing (MLST).<bold>Methods: </bold>Fecal samples of 235 adult IBD patients were collected from January 2008 to May 2009 and were tested for K. oxytoca, C. difficile toxin, and other pathogens by standard microbiological methods. Clinical data and disease activity scores were collected. K. oxytoca isolates were tested for toxin production using cell culture assays. A total of 45 K. oxytoca isolates from IBD patients, healthy, asymptomatic carriers and from patients with antibiotic-associated hemorrhagic colitis in part from our strain collection were tested for their clonal relationship using MLST.<bold>Results: </bold>The prevalence of K. oxytoca in IBD overall was 4.7%. Eleven K. oxytoca isolates were detected. Two of 11 isolates were tested positive for toxin production. There was no significant difference in the distribution of K. oxytoca isolates between the groups (active vs. remission in UC and CD). MLST yielded 33 sequence types. K. oxytoca isolates from IBD did not cluster separately from isolates from asymptomatic carriers.<bold>Conclusions: </bold>Our data demonstrate that toxin (tilivalline)-producing K. oxytoca is not associated with IBD flares. [ABSTRACT FROM AUTHOR]