Abstract
Background
Hospitalized patients are at risk of colonization with a range of healthcare-associated bacterial pathogens, including C. difficile. In patients admitted to intensive care units (ICUs), in whom C. difficile infection (CDI) is associated with increased morbidity and mortality. To understand the risk for acquisition of C. difficile and development of CDI, we monitored ICU patients daily for shedding of C. difficile by culture.
Methods
We conducted a secondary analysis of daily rectal/fecal swab samples collected from medical ICU patients of a 720-bed academic medical center in Chicago, IL. Selective culture for C. difficile was performed on swab samples from patients who had 2 or more samples obtained using selective media. Confirmation of putative C. difficile isolates was done by specific PCR assays for the 16S rRNA-encoding gene and the toxin genes tcdA, tcdB, cdtA and cdtB. Clinical testing for CDI was performed using the Xpert® C. difficile PCR assay (Cepheid). Clinical and demographic metadata were collected at bedside and by electronic medical record review.
Results
Culture was attempted on 2106 swab samples from 451 patients (486 ICU admissions) (Figure 1). A mean of 4.33 samples was obtained from each patient. C. difficile was isolated from 211 (10%) samples from 79 patients (Table 1). The first sample was positive by culture for 48 (9.9%) of patient admissions to the ICU. 31 (6.4%) patients who were initially negative by culture had a subsequent sample from which C. difficile was isolated. Persistence of culture-positivity varied from patient to patient (Figure 2). Of 80 patients who were tested for CDI based on physician suspicion, 12 patients had a positive Cepheid PCR test; 9 had diarrhea and were treated for CDI.
Conclusion
Surveillance for shedding of C. difficile by daily culture reveals that patients admitted to the ICU can shed the pathogen intermittently without attributable disease. This can be in the form patients who are admitted carrying the organism as well as those who appear to acquire the organism during their stay. It is unclear whether patient or microbiome factors underlie the differences seen in patterns of shedding. Furthermore, intermittent shedding may reflect multiple episodes of exposure to C. difficile spores and asymptomatic shedding without stable colonization.
Disclosures
All authors: No reported disclosures.