A modified pulsed-field gel electrophoresis (PFGE) protocol for subtyping previously non-PFGE typeable isolates of Clostridium difficile polymerase chain reaction ribotype 001

A modified pulsed-field gel electrophoresis (PFGE) protocol was developed and applied to 50 isolates of the UK epidemic strain of Clostridium difficile, polymerase chain reaction (PCR) ribotype 001, to develop a PFGE-based subtyping scheme. This protocol overcame the inherent DNA degradation problems associated with typing this strain of C. difficile by this method, and whole genomic digestion with SmaI restriction enzyme yielded seven distinct and reproducible PFGE banding patterns. Modified PFGE is an appropriate method for subtyping C. difficile PCR ribotype 001 that could be used to improve epidemiological investigations.