Thesis (M.Sc.)--Chulalongkorn University, 2000

The prevalence of C.difficile in 4 groups of 443 patients (446 stool specimens) at Siriraj Hospital during the 7 month (October 1998-April 1999) of the study were 15.38% of premature infants, 10.59% of full-term infants, 21.05% of children with anticancer drugs and 25% of the adult patients with diarrhea. It was shown by polymerase chain reaction (PCR) that only 2 isolates from the premature infants and 18 isolates from the adult patients with diarrhea had toxin A gene while enzyme immunoassay (EIA) could not detect txin A production in both 2 isolates from the premature infants and 5 out of 18 isolates from the adult patients. In order to perform the genotyping the chromosomal DNA from all 20 enterotsigenic C. difficile isolates were digested with Sma I restriction endonuclease and separated by pulsed field gel electrophoresis (PFGE). Four different pulsotypes ; A, B, C and D were obtained Fourteen isolates from 11 adult patients with diarrhea were pulsotype a which was the major pulsotype. Seven isolates from 5 adult patients with diarrhea and from 2 premature infants which were only toxin A gene positive by PCR but not toxin A positive by EIA were all pulsotype B or its subtype. PCR has been shown to be a sensitive and useful tool in the detection of the toxigenic C.difficile. PFGE result indicated that the pulsotype A strain was the predominant type and could be related to nosocomial diarrhea. The results obtained should be benefical for patients in both prevention and treatment of this infection.