By Carol A. Kemper, MD, FACP,
Clinical Associate Professor of Medicine,
Stanford University, Division of Infectious Diseases,
Santa Clara Valley Medical Center.
Dr. Kemper reports no financial relationships relevant to this field of study
SOURCE: Brown KA, Jones M, Daneman N, et al. Importation, antibiotics, and Clostridium difficile infection in veteran long-term care: A multi-level case-control study. Ann Intern Med 2016;164:787-794.
While the risks for Clostridium difficile infection (CDI) are well-recognized, the basis for the significant variation in CDI incidence found in long-term care across the United States is poorly understood. These authors examined regional risk factors for CDI across Veteran Health Administration long-term care facilities (LTCFs) from 2006 to 2012. VHA is divided into 86 different regions, and there are significant differences between them in the risk of CDI.
Cases of CDI were defined by a positive toxin test three or more days after admission to LTCF or a positive toxin test eight or more weeks after a previous positive result. Various risk factors were included in the analysis, including patient age and comorbidities, use of antibiotics within 28 days, and use of proton pump inhibitors. Estimates of importation of cases were based on the prevalence of CDI within the local acute care facility within the previous eight weeks.
A total of 6,012 CDIs were identified across the VHA regions, ranging from a minimum of 0.6 cases per 10,000 days to a maximum of 31.0 cases per 10,000 days. In unadjusted analyses, the strongest predictors for CDI were total antibiotic use within an LTCF (incidence risk ratio [IRR] 2.86, R2 = 0.63) and importation of cases from the acute care setting (IRR 1.59, R2 = 0.5). Both of these factors varied considerably: Estimated importation of cases varied 100-fold and antibiotic use varied six-fold across regions. Not surprisingly, individual use of antibiotics within the previous 28 days also was a significant risk factor. Other risk factors examined, including age, comorbidity, and proton pump inhibitor use, had little effect on the variability of CDI across regions.
In complex weighted analyses, antibiotic use and importation of cases explained 75% of the regional variability in the incidence of CDI in LTCF. Regional differences in antibiotic use suggested that not only was antibiotic use associated with an increased risk of CDI, but with an increased risk of spreading CD. The authors surmised that the remaining 25% of geographic variability, which was unexplained by their data, may be due to factors such as improved infection control practices and environmental measures at specific facilities.
Certainly a “community burden” of CD must play a significant role in the risk of active CDI within a facility. Our acute care hospital, with two campuses located 17 miles apart, screens all high-risk hospital admissions with rectal swabs for CD PCR (e.g., admissions from SNF or other facilities, dialysis patients, anyone with a history of CDI). The prevalence of CD colonization on admission between the two campuses is 19% vs. 9.7%, and the difference in CD colonization for SNF admissions between the two campuses is 18% vs. 6%. Despite the use of the same infection control and environmental procedures at both facilities, significant differences in CD rates between the two facilities are frequently observed.