title: Longitudinal Investigation of Carriage Rates, Counts, and Genotypes of Toxigenic Clostridium difficile in Early Infancy.
abstract: Asymptomatic infant carriers of toxigenic Clostridium difficile are suggested to play a role in the transmission of C. difficile infection (CDI) in adults. However, the mode of C. difficile carriage in infants remains to be fully elucidated. We investigated longitudinal changes in carriage rates, counts, and strain types of toxigenic C. difficile in infants. Stools collected from 111 healthy infants in Belgium periodically from birth until the age of 6 months were examined by quantitative PCR targeting 16S rRNA and toxin genes. Toxigenic C. difficile was detected in 18 of 111 infants (16%) in the period up to the age of 6 months. The carriage rate of toxigenic C. difficile remained below 5% until the age of 3 months. The carriage rate increased to 13% 1 week after weaning (average age, 143 days) and reached 16% at the age of 6 months. Counts of toxigenic C. difficile bacteria ranged from 10(4) to 10(8) cells/g of stool. Notably, two infants retained >10(8) cells/g of stool for at least several weeks. Average counts in the 18 infants hovered around 10(7) cells/g of stool from the age of 3 days until the age of 6 months, showing no age-related trend. Genotyping of toxigenic C. difficile isolates from the 18 infants revealed that 11 infants each retained a particular monophyletic strain for at least a month. The genotype most frequently identified was the same as that frequently identified in symptomatic adult CDI patients. Thus, toxigenic C. difficile strains-potential causes of CDI in adults-colonized the infants' intestines.
  
  
  
  Our study provides longitudinal data on counts and strain types of toxigenic C. difficile in infants. We found that considerable numbers of toxigenic C. difficile bacteria colonized the infants' intestines. The results of strain typing suggest that toxigenic C. difficile carried by healthy infants could be potentially pathogenic to adults. These results and findings are informative not only for ecological studies but also for efforts to prevent or control the spread of CDI in adults.
authors.affiliation: Yakult Central Institute, Tokyo, Japan Yakult Honsha European Research Center for Microbiology ESV, Ghent-Zwijnaarde, Belgium hiroyuki-kubota@yakult.co.jp.
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Kubota
authors.affiliation: Yakult Central Institute, Tokyo, Japan Yakult Honsha European Research Center for Microbiology ESV, Ghent-Zwijnaarde, Belgium.
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Makino
authors.affiliation: Yakult Honsha European Research Center for Microbiology ESV, Ghent-Zwijnaarde, Belgium.
authors.forename: Agata
authors.initials: A
authors.lastname: Gawad
authors.affiliation: Yakult Central Institute, Tokyo, Japan.
authors.forename: Akira
authors.initials: A
authors.lastname: Kushiro
authors.affiliation: Yakult Central Institute, Tokyo, Japan Yakult Honsha European Research Center for Microbiology ESV, Ghent-Zwijnaarde, Belgium.
authors.forename: Eiji
authors.initials: E
authors.lastname: Ishikawa
authors.affiliation: Yakult Central Institute, Tokyo, Japan Yakult Honsha European Research Center for Microbiology ESV, Ghent-Zwijnaarde, Belgium.
authors.forename: Takafumi
authors.initials: T
authors.lastname: Sakai
authors.affiliation: Yakult Central Institute, Tokyo, Japan Yakult Honsha European Research Center for Microbiology ESV, Ghent-Zwijnaarde, Belgium.
authors.forename: Takuya
authors.initials: T
authors.lastname: Akiyama
authors.affiliation: Yakult Central Institute, Tokyo, Japan Yakult Honsha European Research Center for Microbiology ESV, Ghent-Zwijnaarde, Belgium.
authors.forename: Kazunori
authors.initials: K
authors.lastname: Matsuda
authors.affiliation: Nutricia Research Singapore, Singapore.
authors.forename: Rocio
authors.initials: R
authors.lastname: Martin
authors.affiliation: Nutricia Research, Utrecht, the Netherlands Wageningen University, Wageningen, the Netherlands.
authors.forename: Jan
authors.initials: J
authors.lastname: Knol
authors.affiliation: Yakult Central Institute, Tokyo, Japan Yakult Honsha European Research Center for Microbiology ESV, Ghent-Zwijnaarde, Belgium.
authors.forename: Kenji
authors.initials: K
authors.lastname: Oishi
mesh_terms: D001427:Bacterial Toxins / Q000235:genetics; D001530:Belgium / Q000453:epidemiology; D002353:Carrier State / Q000453:epidemiology* / Q000382:microbiology; D016360:Clostridioides difficile / Q000145:classification / Q000235:genetics / Q000502:physiology*; D015169:Colony Count, Microbial; D019075:Electrophoresis, Capillary; D005243:Feces / Q000382:microbiology; D005260:Female; D005838:Genotype; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008137:Longitudinal Studies; D008297:Male; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D060888:Real-Time Polymerase Chain Reaction; D013997:Time Factors
chemical_list: D001427:Bacterial Toxins; D012336:RNA, Ribosomal, 16S