Clostridium difficile and enterotoxigenic Bacteroides fragilis strains isolated from patients with antibiotic associated diarrhoea.

From the fecal samples of 332 patients with a clinical diagnosis of antibiotic associated diarrhoea (AAD), 131 Clostridium difficile strains were isolated. For detection of toxin A in the isolated strains the enzymatic immunoassay was used. The cytopathic effect was determined on McCoy cell line. PCR was used for the detection of non-repeating and repeating sequences of toxin A gene and non-repeating sequences of toxin B gene. One hundred and six isolated C. difficile strains were TcdA(+)TcdB(+), 10 strains TcdA(-)TcB(+) and 15 were non-toxigenic TcdA(-)TcdB(-). Out of the same fecal samples 50 Bacteroides fragilis strains were isolated. All B. fragilis strains were tested in PCR reaction for fragilysine gene detection (bft). In 9 strains (18%) this gene was detected and the strains could be assumed as enterotoxigenic Bacteroides fragilis (ETBF). In 4 fecal samples toxigenic C. difficile (TcdA(+)TcdB(+)) was found simultaneously with ETBF. One sample contained C. difficile (TcdA(-)TcdB(+)) and ETBF. Out of 4 fecal samples only ETBF was isolated. The cytotoxicity of ETBF strains was tested on HT29/C1 human colon carcinoma cell line. The cytotoxicity titer in the range of 20 and 80 was observed.