Infection Control & Hospital Epidemiology
residents (70.4%) of the 3 primary study wards at the beginning of the study, 109 of 148 new admissions (73.6%) to the 3 primary study wards, and 23 subjects from the dementia unit with mild dementia. Of the 201 LTCF residents screened, 29 (14.4%) were identified as asymptomatic carriers of toxigenic C. difficile. Table 1 shows the baseline characteristics of the asymptomatic carriers and events that occurred during the study. Of the 29 asymptomatic carriers, 21 (72.4%) had received antibiotics within the 3 months prior to their first positive culture and 4 (13.8%) had prior CDI within 90 days. An additional 4 patients had a remote history of CDI between 6 months and 5 years before enrollment. Furthermore, 2 asymptomatic carriers (6.9%) were diagnosed with CDI during the study; neither had a prior history of CDI. Also, 11 carriers (37.9%) were transferred to the hospital 1 or more times during the study period (range, 1–6 transfers), and 18 carriers (62.1%) received antibiotics while in the LTCF. Table 2 provides a summary of the culture results for the 29 asymptomatic carriers, stratified by those who were or were not transferred to the hospital. Moreover, 26 carriers (89.7%) had positive cultures at the time of LTCF admission or at the time the first culture was collected, and 3 carriers (10.3%) had initial negative cultures followed by a positive culture. Of the 29 carriers, 17 (58.6%) had >25 colonies of C. difficile recovered from the swab cultures on 1 or more occasions. In addition, 21 carriers (72.4%) had positive cultures of their groin, skin, and/or envir- onment for toxigenic C. difficile on ≥1 occasion, and 18 carriers (85.7%) were defined as persistent carriers based on detection of the same REA type of toxigenic C. difficile on 2 or more occa- sions. The rows of the 4 carriers linked to transmission are shown in bold type. During the study, 37 primary (ie, nonrecurrent) healthcare-
associated CDI cases were diagnosed, including 26 hospital- associated cases (70%) and 11 LTCF-associated cases (30%). Of the 37 patients with healthcare-associated CDI, 35 (94.6%) were male. In addition, 22 of the hospital-associated cases had their onset in the hospital, and 4 had their onset in the community after discharge. Furthermore, 4 (15.4%) of the hospital-associated CDI cases were transferred to the study LTCF during treatment, and 3 (11.5%) were transferred to non-VA LTCFs. Table 3 provides an overview of the REA typing results for the
29 asymptomatic carriers and the 37 CDI cases. The overall dis- tribution of REA groups was similar for carriers and CDI cases. For both carriers and CDI cases, the most common REA group was the BI epidemic strain. The second most common REA group was DQ, a newly recognized binary toxin-positive strain related to, but distinct from, the epidemic REA BI strain.27 Of the 18 carriers with toxigenic C. difficile detected on >1 occasion, 15 (83.3%) had strains with the same REA type for each isolate tested. Figure 1 provides an overview of the analysis of potential
transmission events. Based on REA grouping and ward exposure, 12 of the 37 healthcare-associated CDI cases (32.4%) were potentially linked to LTCF asymptomatic carriers and 4 (10.8%) were potentially linked to LTCF CDI cases. However, based on WGS analysis with 0–2 SNP differences (indicating transmission events), only 4 of the 16 potential ward transmissions (25%) were deemed true transmissions. Furthermore, 3 additional putative transmissions that were non–ward based were identified based on 0–2 SNP differences on WGS and concurrent stays on separate hospital or LTCF wards. Thus, 7 of the 37 CDI cases (18.9%) were linked to LTCF residents with LTCF-associated CDI or asymptomatic carriage based on ward or nonward healthcare-facility exposure and WGS results, including 3 of 26
911
Table 1. Baseline Characteristics of the 29 Long-Term Care Facility Residents with Asymptomatic Carriage of Toxigenic Clostridium difficile and Events During the Study
Characteristic
Baseline Age, mean y (range) Male sex
Previous hospitalization within 90 d Previous CDI within 90 d Previous CDI at any time
Antibiotic treatment within 90 d Proton pump inhibitor
Admitted for post-acute rehabilitation
Medical conditions Diabetes
Heart disease
Chronic lung disease Cancer
Cerebrovascular accident Major surgery within 90 d Cirrhosis
End-stage renal disease Spinal cord injury Fecal incontinence MRSA colonization
Events during the study Antibiotic therapy
Length of stay in LTCF, median d (range) Hospital admission 1 or more times No. of hospital admissions, mean (range) CDI diagnosis
Discharged to home Died in LTCF
LTCF, long-term care facility. aUnless otherwise specified.
hospital-associated CDI cases (11.5%) and 4 of 11 LTCF- associated CDI cases (36.4%). Of the 7 transmissions linked to LTCF residents, 5 (71.4%) were linked to asymptomatic carriers, and 2 (28.6%) were linked to to CDI cases. All transmissions were of epidemic BI strains. During the study period, no incident hospital-associated CDI cases were linked to other hospital- associated CDI cases. Figure 2 provides LTCF and hospital ward locations of the donor LTCF asymptomatic carriers or CDI cases and the linked
No. (%)a
68.0 (48–90) 29 (100) 23 (79.3) 4 (13.8) 8 (27.6) 21 (72.4) 15 (51.7) 18 (62.1)
17 (58.6) 14 (48.3) 8 (27.6) 11 (37.9) 4 (13.8) 6 (20.7) 2 (6.9) 2 (6.9)
5 (17.3) 2 (6.9)
12 (41.4) 18 (62.1)
67 (7–181) 11 (37.9) 0.9 (0–6) 2 (6.9)
26 (89.7) 3 (10.3)
NOTE. CDI, Clostridium difficile infection; MRSA, methicillin-resistant Staphylococcus aureus;
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