C. difficile infections (CDI) disproportionally affect the elderly due to their underlying comorbidities, immune senescence, and microbiome changes. Elderly patients are also more likely to be infected by the NAP1/027 C. difficile strain, possibly due to frequent exposure to antibiotics and healthcare. We are describing the trend in the CDI incidence and NAP1 strain type in the elderly population of Monroe County, NY.
We conducted population and laboratory-based surveillance for CDI during October 2009 to 2014 in Monroe County, NY as part of the CDC Emerging Infections Program. An incident CDI case was defined as a positive C. difficile stool specimen greater than 8 weeks after a previous positive test. A recurrent case was defined as positive stool specimen between 2-8 weeks after a previous positive test. Cases were divided into 4 epidemiologic classifications: community associated (CA), community-onset health care-associated (CO-HCA), hospital onset (HO), and nursing home onset (NHO), depending on the location at the time of testing and exposure to healthcare in the 12 weeks prior to their diagnosis. Nucleic acid amplification testing was implemented in 1 lab in 2009 and all labs by 2011. Isolate molecular testing was performed on a random sample of stool specimens from 2 labs from October 2009 to 2013.
We identified 4,722 incident CDI cases in elderly aged ≥ 65 years, representing 56% of all cases; 21% had a first recurrence. In 2010, the incidence was 899 per 100,000 population; it increased to 982 in 2011 and decreased to 643 in 2014. The decrease in CDI incidence varied by age group and by epidemiologic classification (fig.1). The magnitude of the decrease was larger for cases aged ≥85 years and for NHO cases. The 30 days mortality rate decreased by 57% in 2014 compared to 2010 to a rate of 39 per 100,000 population. Five hundred fifty three C. difficile isolates were tested; the percentage NAP1/027 strain decreased from 38% to 15% between 2009 and 2013.
The incidence and mortality of CDI is decreasing in the Monroe County, NY elderly population, especially in patients aged ≥85 years and in nursing homes. Further studies are needed to understand the factors leading to this decrease, including the effect of the change in strain type.
R. Tsay, None
D. Nelson, None
A. Gellert, None
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