title: Characterisation and carriage ratio of Clostridium difficile strains isolated from a community-dwelling elderly population in the United Kingdom.
abstract: BACKGROUND
  Community-associated Clostridium difficile infection (CDI) appears to be an increasing problem. Reported carriage rates by C. difficile are debatable with suggestions that primary asymptomatic carriage is associated with decreased risk of subsequent diarrhoea. However, knowledge of potential reservoirs and intestinal carriage rates in the community, particularly in the elderly, the most susceptible group, is limited. We have determined the presence of C. difficile in the faeces of a healthy elderly cohort living outside of long-term care facilities (LCFs) in the United Kingdom.
  
  
  METHODS
  Faecal samples from 149 community-based healthy elderly volunteers (median age 81 years) were screened for C. difficile using direct (Brazier's CCEY) and enrichment (Cooked Meat broth) culture methods and a glutamate dehydrogenase (GDH) immunoassay. Isolates were PCR-ribotyped and analysed for toxin production and the presence of toxin genes.
  
  
  RESULTS
  Of 149 faecal samples submitted, six (4%) were found to contain C. difficile. One particular sample was positive by both the GDH immunoassay and direct culture, and concurrently produced two distinct strain types: one toxigenic and the other non-toxigenic. The other five samples were only positive by enrichment culture method. Overall, four C. difficile isolates were non-toxigenic (PCR-ribotypes 009, 026 (n = 2) and 039), while three were toxigenic (PCR-ribotypes 003, 005 and 106). All individuals who had a positive culture were symptom-free and none of them had a history of CDI and/or antibiotics use in the 3 month period preceding recruitment.
  
  
  CONCLUSIONS
  To our knowledge, this is the first study of the presence of C. difficile in healthy elderly community-dwelling individuals residing outside of LCFs. The observed carriage rate is lower than that reported for individuals in LCFs and interestingly no individual carried the common epidemic strain PCR-ribotype 027 (NAP1/BI). Further follow-up of asymptomatic carriers in the community, is required to evaluate host susceptibility to CDI and identify dynamic changes in the host and microbial environment that are associated with pathogenicity.
authors: National Institute for Health Research Biomedical Research Centre, Royal Liverpool and Broadgreen University Hospitals National Health Service Trust, Liverpool, United Kingdom.
authors: Fabio
authors: F
authors: Miyajima
authors: Paul
authors: P
authors: Roberts
authors: Andrew
authors: A
authors: Swale
authors: Valerie
authors: V
authors: Price
authors: Maureen
authors: M
authors: Jones
authors: Michael
authors: M
authors: Horan
authors: Nicholas
authors: N
authors: Beeching
authors: Jonathan
authors: J
authors: Brazier
authors: Christopher
authors: C
authors: Parry
authors: Neil
authors: N
authors: Pendleton
authors: Munir
authors: M
authors: Pirmohamed
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D002353:Carrier State / Q000453:epidemiology*; D016360:Clostridioides difficile / Q000302:isolation & purification*; D003710:Demography; D005260:Female; D006801:Humans; D008297:Male; D012111:Residence Characteristics / Q000706:statistics & numerical data*; D006113:United Kingdom / Q000453:epidemiology