Clostridium difficile Colonization of Nursing Home Residents

To the Editor—Clostridum difficile is a leading cause of infectious diarrhea in nursing homes. ¹ Evidence-based infection control guidelines are needed to reduce transmission of C. difficile in nursing homes. These guidelines should account for the prevalence of C. difficile in the nursing home environment. The primary objective of this project was to assess the proportion of nursing home residents colonized with toxigenic C. difficile.

A random sample of community-based nursing home residents (n=40; 10%) and Veterans Affairs Community Living Center (VA CLC) residents (n=40; 20%) were selected retrospectively from 2 cohort studies on MRSA colonization and transmission. ^{2 , 3} The studies enrolled 401 residents from 13 community-based nursing homes in Maryland and Michigan and 200 residents from 5 VA CLCs in 4 states and the District of Columbia. Selection within the community-based facilities was designed to be representative of all nursing home residents. However, in the VA CLCs, 2 groups of residents were enrolled: residents with a recent (within 1 year) history of MRSA colonization and residents without recent MRSA colonization. All VA CLC residents with recent MRSA colonization were approached for enrollment. A random sample of residents without recent MRSA colonization was approached for enrollment to provide a representative sample. Specimens from the perianal skin were taken from enrolled residents. Notably, diarrhea was reported for 2%–3% of the study participants. No C. difficile outbreaks were reported during the studies.

Culture-based methods were used to detect toxigenic C. difficile in perianal swabs. Resident swabs from the perianal skin were placed in cycloserine cefoxitin mannitol broth with taurocholate and lysozyme broth (Anaerobe Systems; Morgan Hill, CA) at 35°C in anaerobic conditions, and growth was observed at 24 hours, 48 hours, and 7 days. If growth was observed, the culture was transferred to a blood agar plate and incubated in aerobic conditions at 35°C for 48 hours. Any bacteria growth was identified using RapID Ana II system (Remel, Lenexa, KS). Toxins A and B and C. difficile glutamate dehydrogenase detection were determined using C Diff Quik Chek Complete kits (TechLab, Blacksburg, VA). ⁴

Among the community-based nursing homes residents, 1 of 40 residents had perianal skin swabs that tested positive for toxigenic C. difficile (2.5%; 95% CI, 0.1%–13.2%). None of the 40 VA CLC residents tested positive for toxigenic C. difficile (0%; 95% CI, 0.0%–8.8%).

These rates are slightly lower than those reported in the literature. Based on data from 9 eligible studies that included 1,371 subjects, a recent systematic review found that 14.8% (95% CI, 7.6%–24.0%) of LTCF residents are asymptomatic carriers of toxigenic C. difficile. ⁵ The systematic review included 21 LTCFs across 4 countries and 4 states. In contrast, our populations covered 18 nursing homes in 6 states. The facilities in the review with the highest reported rates of C. difficile colonization had also experienced recent outbreaks of C. difficile infection, which increased their estimates. Our results should reassure nursing homes that prevalence of toxigenic C. difficile is low during endemic periods. Standard precautions should be sufficient to prevent transmission under nonepidemic conditions.