Distribution of toxinotypes and detection of binary toxin in 199 Clostridium difficile strains at a university hospital, Montpellier, France
Abstract number: p525
Boulier A., Marchandin H., Decre D., Campos J., Devine R., Jean-Pierre H.
Clostridium difficile is the most common agent of nosocomial diarrhoea. The aim of this study was to characterize the clinical strains of C. difficile isolated in our hospital over a 18-months period by toxinotyping and binary toxin gene detection.
Traditional methods included direct detection of toxin A on stool samples using the immunological kit C. difficile Toxin A test, Oxoid® and anaerobic culture on cycloserine-cefoxitin-fructose agar incubated during 7 days. All C. difficile strains were tested for toxin A production with the immunological method. Toxinotyping was performed as described by Rupnik et al. (A3 and B1 fragments) and binary toxin gene detection was done by PCR using cdtB pos and cdtB rev primers.
A total of 199 C. difficile strains were collected from 159 patients between January 2004 and June 2005. Detection of toxin A was positive for 145 isolates and only for 53 stool specimens. Among the 199 strains, toxinotyping revealed that 156 strains were phenotypically A+/B+ (78.5%), 37 A-/B- (18.5%) and 6 (3%) A-/B+. Strains A+/B+ mainly belonged to toxinotype 0 (n = 127, 63,5% of the total strains), the 29 other were identified as variant toxinotypes III, IV, V, VI, IX, XII, XXI and XXII. The production of toxin A could not be detected with the commercial kit in 11 strains with toxinotypes 0 (n = 9), V (n = 1), and XXI (n = 1). Among the 37 strains A-/B-, 31 isolates were non-toxigenic and 6 were toxinotype XIb. The 6 isolates A-/B+ belonged to toxinotypes VIII (n = 4) and X (n = 2). Detection of binary toxin gene was positive for 31 strains (15.4%), which grouped into 8 variant toxinotypes (0, III, IV, V, VI, IX, X and XXII). Identical toxinotypes were observed in 19 of the 29 patients with successive C. difficile isolates whereas different toxinotypes were found for the 10 remaining patients.
These data confirmed that traditional methods are less effective than molecular methods to detect C. difficile toxins. A total of 12 toxinotypes were identified among the 199 C. difficile strains, with high prevalence of toxinotype 0 as previously observed. More variant toxinotypes were detected in comparison with previous European studies. We found 3% of virulent A-/B+ C. difficile strains. A relatively high level of strains with binary toxin gene (15.4%) was observed in comparison with Asian data (1.6%) and French data (6%). Toxinotyping showed that relapse occurred in 19 cases and reinfection in 10 cases.
|Session name:||XXIst ISTH Congress|
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