Project description:Clostridium difficile (C. difficile) strains belonging to PCR ribotype 027, PFGE type NAP1, REA type B1 and toxinotype III, termed NAP1/027, have been implicated in the increased frequency of outbreaks of Clostridium difficile-associated diarrhoea (CDAD) in North America and Europe. The NAP1/027 strains appears to be more virulent with an increased mortality and frequency of relapse. Current European C. difficile microarrays are designed to the first sequenced and annotated C. difficile complete genome - strain 630 (ribotype 12). A high density oligonucleotide microarray was designed to C. difficile 630 (CD630) sequence and extra probes corresponding to two PCR ribotypes O27 strains C. difficile R20291 and QCD-32g58 were also included. Comparative genomic hybridisation was used to identify markers of ribotype 027 strains and markers to identify CD630. Strains hybridised to the array included the most prevalent ribotypes found in the UK and Europe (106 and 001) as well as the emerging hypervirulent ribotype 078.