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Clostridioides difficile Infection May Be Underdiagnosed in Health Care Facilities, Study Finds


A study of hospitals and long-term care facilities in Louisville, Kentucky, found low rates of Clostridioides difficile testing in patients with new-onset diarrhea who are frequently infected.

Clostridioides difficile infection (CDI) may be underdiagnosed if a high proportion of patients in hospitals and long-term care facilities (LTCFs) presenting with diarrhea do not have stool samples collected for testing. A study published in International Journal of Infectious Diseases evaluated stool sample collection and CDI testing frequency in adults with new-onset diarrhea to assess the potential for underdiagnosis in hospitals and LTCFs.

CDI is a significant cause of morbidity and mortality in hospitalized patients and those in LTCFs, with prior antibiotic use serving as a main risk factor in addition to older age and comorbidities. Mild to severe diarrhea is a hallmark symptom of CDI, and stool sample testing is necessary to confirm the diagnosis.

The cross-sectional, observational study identified patients with new-onset diarrhea in all hospitals and a selection of LTCFs in Louisville, Kentucky, to find out how frequently stool specimens were collected and tested for CDI.

Nine hospitals with 3532 beds were included in a 7-day observational period during which trained research clinicians visited each ward daily and identified adult patients who had at least 1 loose stool in the last 24 hours. If further evaluation showed that the patient had 3 or more loose stools in the past 24 hours and that diarrhea was not present in the preceding 24 hours, they were considered to have new-onset diarrhea. Fourteen LTCFs with 1205 beds also were observed in a similar manner for 14-day periods. Only Louisville residents were included in the analysis.

Of 2565 hospitalized adults during the observational period, 416 had at least 1 loose stool in the past 24 hours and 245 had new-onset diarrhea. Hospitalized patients had 14,042 inpatient-days between them, and the rate of new-onset diarrhea in this group was 1.7 cases per 100 inpatient-days; 167 patients were Louisville residents.

Stool specimens were collected from 53 of 167 patients (32%) with new-onset diarrhea in the study cohort, with similar collection frequency on weekends and weekdays. Overall, 12 of the 53 samples (23%) were positive for CDI. The estimated CDI incidence in hospitalized Louisville residents was 12.3 cases per 10,000 inpatient-days.

Of 743 LTCF residents observed, 241 had at least 1 loose stool in the previous 24 hours, and 63 had new-onset diarrhea. The LTCF residents had 10,402 resident-days between them over the 14-day observation period, and the incidence of new-onset diarrhea was 0.6 per 100 resident-days. Of 20 stool specimens from LTCF residents during the observation period, 9 (45%) were positive for CDI. The LTCF-based CDI incidence was 8.6 per 10,000 resident-days. None of the patients with new-onset diarrhea were hospitalized, and no outbreaks of diarrheal disease were reported.

In this study group, only half of the diarrhea episodes identified were recorded in electronic medical records, and interviewing nursing staff proved most effective in identifying patients with new-onset diarrhea.

The findings suggest CDI underdiagnosis might be common in health care facilities in Louisville. New-onset diarrhea frequently occurred in this study, and C diff was often identified in collected specimens. However, only 32% of hospitalized patients and LTCF residents with new-onset diarrhea had their stool samples collected.

The study was limited by the relatively brief observation periods and use of different study periods for different health care facilities. It was also limited to Louisville, potentially limiting its generalizability, although it is likely representative of many midsize US cities. The presence of researchers may also have influenced stool collection practices, but staff took precautions not to do so. Even so, the findings point to a low frequency of stool collection and testing for CDI in hospitals and LTCFs.

“Prospective, population-based surveillance studies designed to test all patients with new-onset diarrhea are particularly needed to better understand the extent of CDI underdiagnosis and the impact of CDI underdiagnosis on the true burden of CDI in the United States,” the authors concluded.


Angulo FJ, Oliv SP, Carrico R, et al. Frequency of stool specimen collection and testing for Clostridioides difficile of hospitalized adults and long-term care facility residents with new-onset diarrhea in Louisville, Kentucky. Int J Infect Dis. Published online April 24, 2022. doi:10.1016/j.ijid.2022.04.046

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