Clostridium difficile strains not producing Toxin A,but producing Toxin B [toxA(-)tox B(+)]--etiologic agent of antibiotic associated diarrhoea (AAD) in Poland

Previously, toxin A-negative/toxin B-positive Clostridium difficile strains were not thought to be associated with clinically significant diseases. In our study among 159 tested C. difficile strains isolated from feacal samples from 413 patients with antibiotic associated diarrhoea (AAD) 17 strains (11%) were negative in the "Culturette Brand Toxin" CD (Becton-Dickinson) for detection toxin A and positive in the TOX A/B test, designed for detection of both toxins. The conserved regions of both toxin genes were detectable in all of isolates studied by the PCR. Nine of these C. difficile strains had a deletion in the A gene and remaining 8 strains, revealed an amplicon with the expected size of approximately 2500 bp. In this paper we described the first time the toxin A-negative/toxin B-positive C. difficile strains with deletion in toxin A gene, isolated from the faecal samples of patient with AAD in Poland.