Clostridium difficile, 2012
Clostridium difficile is an anaerobic, spore-forming, Gram-positive bacillus that produces two pathogenic toxins: A and B. C. difficile infections (CDI) range in severity from mild diarrhea to fulminant colitis and death. Transmission of C. difficile occurs primarily in healthcare facilities, where environmental contamination by C. difficile spores and exposure to antimicrobial drugs are common. The primary risk factor for development of CDI in healthcare settings is recent use of antimicrobials, particularly clindamycin, cephalosporins, and fluoroquinolones. Other risk factors for CDI acquisition in these settings are age greater than 65 years, severe underlying illness, intensive care unit admission, nasogastric intubation, and longer duration of hospital stay.
A marked increase in the number of CDI cases and mortality due to CDI has been noted across the United States, Canada, and England. Most notable was a series of large-scale protracted outbreaks in Quebec first reported in March 2003. During this period, Quebec hospitals reported a 5-fold increase in healthcare acquired CDI. These and other healthcare facility (e.g., long-term care facilities) outbreaks have been associated with the emergence of a new more virulent strain of C. difficile, designated North American pulsed field gel electrophoresis type 1 (NAP1), toxinotype III.
Community-associated (CA) CDI is also receiving increased attention. Several cases of serious CDI have been reported in what have historically been considered low-risk populations, including healthy persons living in the community and peripartum women. At least 25% of these cases had no history of recent healthcare or antimicrobial exposure.
In 2009, as part of the EIP, we initiated population-based, sentinel surveillance for CDI at 10 hospital laboratories serving Stearns, Benton, Morrison, and Todd Counties. A CDI case is defined as a positive C. difficile toxin assay on an incident stool specimen from a resident of one of the four counties. A CDI case is classified as healthcare facility-onset (HCFO) if the initial specimen was collected greater than 3 days after admission to a healthcare facility. Community-onset (CO) cases who had an overnight stay at a healthcare facility in the 12 weeks prior the initial specimen are classified as CO-HCFA, whereas CO cases without documented overnight stay in a healthcare facility in the 12 weeks prior the initial specimen result are classified as CA. A more detailed set of case definitions is available upon request.
In 2012, 462 incident cases of CDI were reported in the four sentinel counties (186 per 100,000 population). Sixty-two percent of these cases were classified as CA, 19% as CO-HCFA, and 19% as HCFO. The median ages for CA, COHCFA, and HCFO cases were 51 years, 64 years, and 75 years, respectively. Forty-nine percent of CA cases were prescribed antibiotics in the 12 weeks prior to stool specimen collection compared to 84% of HCFO cases and 86% of CO-HCFA cases. Of the 289 putative CA cases eligible for interview, 220 were interviewed and confirmed as CA cases. Fifty-four percent of CA cases reported antibiotic use in the 12 weeks prior to illness onset date. Most common uses of antibiotics included treatment of ear, sinus, or upper respiratory infections (38%); urinary tract infections (14%); and dental procedures (11%).
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