Detection of Clostridium difficile Toxin A and B Genes
from Stool Samples of Thai Diarrheal Patients by Poly
merase Chain Reaction Technique
SIRIPAN WONGWANICH, MSc*, SIRIPORN RUGDEEKHA, MSc*,
PINTIP PONGPECH, PhD**, CHERTSAK DHIRAPUTRA, MD, BSc***
Affiliation : * National Institute of Health, Department of Medical Sciences, Ministry of Public Health, Nonthaburi 11000,
** Deparment of Microbiology, Faculty of Pharmaceutical Sciences, Chulalongkorn University, Bangkok 10330,
*** Deparment of Microbiology, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok 10700, Thailand.
AbstractThe prevalence of Clostridium difficile isolated from stools of Thai adult patients with sus
pected antibiotic-associated diarrhea (AAD) was 18.64 per cent.
The recovery rate of toxin genes (tctiA 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 tax gene
positive strains.
Although, there were some discrepancy results for certain samples, the direct PCR-based
detection of C. difficile tax genes in stool samples seems to be the appropriate method for the diag
nosis 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-asso
ciated diarrhea (AAD) or antibiotic-associated colitis (AAC) patients may give some evidence for clini
cians in hospitals who cannot perform PCR-based or EIA-based techniques, since 48.6 per cent of the
isolates were demonstrated as toxigenic strains.
Keywords : Clostridium difficile, Diarrhea, Polymerase Chain Reaction
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