Clostridium difficile: Pathogenesis
Colonization
- Colonization with C. difficile is much more common than symptomatic infection. The majority of people who have C. difficile in their stool do not develop any symptoms.
- Rates of colonization vary amongst populations
- Healthy adults: 3%
- Long-term care: 4-20% (7.1% in 1993 study of St. Paul nursing homes) (1)
- Outbreaks in long-term care: up to 30%
- Asymptomatic colonization may be protective against symptomatic disease. In one study, only 1% of patients colonized with C. difficile at time of admission developed disease, while 3.6% of patients not colonized developed disease. (2)
Transmission
- Acquisition of C. difficile is via the fecal-oral route.
- Most commonly occurs environmentally
- Contaminated hands of health care workers
- Contaminated objects (commodes, telephones, thermometers)
- Decontamination of environment can be difficult due to the presence of spores, which are difficult to kill.
Development of Infection
- Systemic antibiotic therapy
causes disruption of gastrointestinal flora
- Exposure to C. difficile during or shortly after completion of antibiotics can result in development of diarrheal disease
- Host susceptibility factors also important (strong antibody responses to toxins are protective)
References:
1. Walker KJ et al. Clostridium difficile colonization in residents of long-term care facilities: prevalence and risk factors. J Am Ger Soc. 1993 ; 41(9):940-6.
2. Shim JK, Johnson S, Samore MH, Bliss DZ, Gerding DN. Primary symptomless colonisation by Clostridium difficile and decreased risk of subsequent diarrhoea. Lancet 1998;351:633-6
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