Epidemic potential and antimicrobial resistance in Clostridium difficile

Abstract

Clostridium difficile is the most commonly diagnosed cause of infectious hospital-acquired diarrhoea. C. difficile was first isolated in 1935 but not identified as the main causative agent of antibiotic-associated diarrhoea (AAD) and pseudomemranous colitis (PMC) until 1977. The spectrum of disease caused by C. difficile ranges from asymptomatic colonisation to colitis that can progress to more severe PMC. Complications include colonic perforation and death. The term C. difficile-associated diarrhoea (CDAD) is used to describe the symptomatic manifestations of the disease, thus excluding asymptomatic colonisation. Hospital inpatients with CDAD are generally elderly and have several comorbid conditions. The majority of these patients have been exposed to antimicrobials that reduce ?colonisation resistance? of the large intestine allowing subsequent infection with C. difficile. Whether infection progresses to disease is determined by many factors such as antibiotic exposure, age and comorbidities, and others that are as yet unknown. Acquisition of C. difficile is facilitated by its ability to form spores that are resistant to many disinfectants, allowing it to remain viable in the hospital environment for long periods of time. Toxigenic isolates of C. difficile usually produce two toxins, toxin A and toxin B, and these are thought of as the major virulence factors. CDAD is a major financial burden on healthcare systems, with patients spending an extra one?three weeks in hospital costing US$5?10,000 per episode.