Detection of Clostridium difficile toxin A and B genes from stool samples of Thai diarrheal patients by polymerase chain reaction technique.

The prevalence of Clostridium difficile isolated from stools of Thai adult patients with suspected antibiotic-associated diarrhea (AAD) was 18.64 per cent. The recovery rate of toxin genes (tcdA and tcdB) by polymerase chain reaction (PCR) from stool samples yielded almost the same compared to the recovery rate of the toxin detection by enzyme immunoassay (EIA), which were 44.9 per cent and 46.7 per cent, respectively. Correlation of toxin gene detection by PCR and toxin detection by EIA was 90.6 per cent. All but one stool sample, the tcdA gene was detected together with the tcdB gene. Both genes were always detected together from tox gene-positive strains. Although, there were some discrepancy results for certain samples, the direct PCR-based-detection of C. difficile tox genes in stool samples seems to be the appropriate method for the diagnosis of C. difficile diarrhea. The PCR assay should be a recommended technique to be used routinely in laboratories. Further optimization of the technique to increase the sensitivity of the PCR assays is still needed. However, a quantitative isolation of the organism from stools of suspected antibiotic-associated diarrhea (AAD) or antibiotic-associated colitis (AAC) patients may give some evidence for clinicians in hospitals who cannot perform PCR-based or EIA-based techniques, since 48.6 per cent of the isolates were demonstrated as toxigenic strains.