Toxin genes (tdcA, tdcB, cdtA and cdtB) of Clostridium difficile strains isolated from patients with C.difficile-associated diarrhoea in Turkey

Abstract number: P781

Deniz U., Ulger Toprak N., Aksu B., Soyletir G.

Background:Clostridium difficile is the causative agent of a spectrum of gastrointestinal syndromes in humans ranging from diarrhoea to severe life-threatening colitis. Pathogenesis primarily involves the action of two large clostridial cytotoxins, toxin A and toxin B, which are encoded by the tcdA and tcdB genes, respectively. Reports on toxin A variant strains (tcdA negative, tcdB positive), and the recent emergence of the epidemic binary toxin positive C. difficile strains in Europe, USA and Canada lead to important changes in epidemiology of C. difficile-associated diarrhoea (CDAD).

Objective: This study investigated the toxin genes of C. difficile strains isolated from hospitalised patients with antibiotic-associated diarrhoea (AAD).

Methods: In the period of September 2006-March 2008, the stool samples from 633 patients with nosocomial AAD at Marmara University Hospital were analyzed for C. difficile by cultivation, toxin A/B immunoenzymatic detection (ImmunoCard Toxins A&B, Meridian Diagnostics, Inc., Ohio, USA). In addition, culture filtrates of the isolates were also screened for the toxin A/B by immunoassay test. Genes for toxin A (tcdA), toxin B (tcdB), binary toxin (cdtA and cdtB) were determined by PCR.

Results: Fifty stool specimens yielded C. difficile on culture; while only 30 of these were positive by toxin immunoassay test. However; an additional 6 samples which were negative by direct toxin test were found to be toxin positive when assay was performed on culture filtrates of the C. difficile isolates, giving a sensitivity for direct toxin assay as 88%.

The toxin A and toxin B genes were detected in all strains (n: 36) isolated from samples that were toxin positive either directly or from culture filtrates. There were neither variant strains (tcdA-negative and tcdB-positive) nor binary toxin gene positive isolates among tested bacteria.

Conclusion: Our findings form a database about toxin genes of C. difficile in hospitalised patients with AAD in Turkey, where molecular investigation of toxin-producing C. difficile strains has not been performed so far. Despite absence of isolates producing new toxin variants or binary toxin in this study, it seems to be important to monitor the isolates for the emergence of those strains which still cannot be detected by commercially available tests, in order to control and prevent the outbreaks.

Session Details

Date: 16/05/2009
Time: 00:00-00:00
Session name: 19th European Congress of Clinical Microbiology and Infectious Diseases
Location: Helsinki, Finland, 16 - 19 May 2009
Presentation type:
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