title: Characteristics of Clostridium difficile strains isolated from asymptomatic individuals and from diarrheal patients.
abstract: OBJECTIVE
  To characterise genotypes of Clostridium difficile strains isolated from asymptomatic individuals and patients with diarrhea.
  
  
  METHODS
  Fecal specimens from 235 asymptomatic infants <12 months, 76 asymptomatic children 1-11 years and 132 adult patients with antibiotic-associated and non-antibiotic-associated diarrhea obtained from Siriraj Hospital, Bangkok from October 1998 to April 1999 were examined for C. difficile by cycloserine-cefoxitin-fructose agar culture. The presence of the C. difficile toxin A gene was determined by specific PCR with the use of primers 5-(CCC AAT AGA AGA TTC AAT ATT AAG CTT)-3 and 5-(GGA AGA AAA GAA CTT CTG GCT CAC TCA GGT)-3. All C. difficile isolates were subsequently genotyped by pulsed-field gel electrophoresis (PFGE).
  
  
  RESULTS
  The C. difficile strains were found in 28 (11.9%) asymptomatic infants, 16 (21.1%) asymptomatic children and 33 (25%) adult patients. In total, 14 PFGE types and eight subtypes designated as types A, B, C, D, E, F, G, H, I, J, K, L, M and N, and A1, A2, A3, A4, B1, B2, B3 and E1, respectively, were identified. Only two isolates from infants and 18 isolates from adult patients were toxin A gene positive by PCR. Both isolates of toxigenic C. difficile were from infants in the same ward and were PFGE type B. PFGE type A was the predominant type among all toxigenic isolates (12 of 18 isolates) from adult patients. The other PFGE types of toxigenic C. difficile found in adult patients were: type A1, one isolate; type B, four isolates; and type C, one isolate. Types B2 and D were identified in 38.5% and 46.2%, respectively, of the toxin A gene-negative isolates of C. difficile from infants.
  
  
  CONCLUSIONS
  These results revealed the occurrence of three distinct clusters from different wards in Siriraj Hospital. The toxigenic C. difficile of PFGE type A and related subtypes was a predominant infective clone in adult patients, whereas non-toxigenic C. difficile types B2 and D were encountered in asymptomatic infants. This information can be useful in epidemiologic investigations.
authors.affiliation: Department of Medical Sciences, National Institute of Health, Nonthaburi, Thailand. siripan@dmsc.moph.go.th
authors.forename: S
authors.initials: S
authors.lastname: Wongwanich
authors.forename: P
authors.initials: P
authors.lastname: Pongpech
authors.forename: C
authors.initials: C
authors.lastname: Dhiraputra
authors.forename: S
authors.initials: S
authors.lastname: Huttayananont
authors.forename: P
authors.initials: P
authors.lastname: Sawanpanyalert
mesh_terms: D000328:Adult; D001427:Bacterial Toxins / Q000235:genetics; D002648:Child; D002675:Child, Preschool; D016360:Clostridioides difficile / Q000145:classification* / Q000235:genetics / Q000302:isolation & purification; D004269:DNA, Bacterial / Q000235:genetics / Q000302:isolation & purification; D003967:Diarrhea / Q000382:microbiology*; D016521:Electrophoresis, Gel, Pulsed-Field; D004761:Enterocolitis, Pseudomembranous / Q000382:microbiology*; D004768:Enterotoxins / Q000235:genetics; D005243:Feces / Q000737:chemistry / Q000382:microbiology; D014644:Genetic Variation; D016680:Genome, Bacterial; D006801:Humans; D007223:Infant; D008875:Middle Aged; D016133:Polymerase Chain Reaction; D013785:Thailand
chemical_list: D001427:Bacterial Toxins; D004269:DNA, Bacterial; D004768:Enterotoxins; C041348:tcdA protein, Clostridium difficile