Stool Specimen Collection Could Offset C Difficile Infection Underdiagnosis Issues

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New-onset diarrhea is common among inpatients and residents of long-term care facilities.

While underdiagnosing clostridium difficile infections (CDI) is a common issue in hospitals and long-term care facilities (LTCF), stool specimen collection could help close this gap and gauge the true spread of CDI.

A team, led by Frederick J. Angulo, DVM, PhD, Medical Development and Scientific/Clinical Affairs, Pfizer Vaccines, determined stool specimen collection and C difficile testing frequency in inpatient and long-term care facility residents with new-onset diarrhea.

Underdiagnosing C Difficile Infections

One important aspect of identifying the spread of C difficile infections can be stool specimen collection. Recently, there have been various studies based in Europe that have attempted to estimate the extent of C difficile infection underdiagnosis because of undertesting or inappropriate testing. However, this has previously not been explored in the US.

“Despite the high CDI disease burden in the United States, the incidence of CDI may be underestimated if a high proportion of inpatients and LTCF-residents with diarrhea do not have a stool specimen collected for CDI testing,” the authors wrote.

In the cross-sectional study, the investigators examined patients in all wards of 9 adult hospitals and 14 long-term care facilities in Louisville to identify new-onset diarrhea.

The study population included 3532 beds in the adult hospitals and 1205 beds in the long-term care facilities.New-onset diarrhea was defined as at least 3 loose stools in the past 24 hours and not present in the preceding 24 hours.

The investigators identified adult patients using electronic medical record review, nurse interviews, and patient interviews during a 1-2 week observation period between 2018-2019.

The Data

Overall, there were 167 inpatients with new-onset diarrhea in Louisville included in the study, accounting for 9731 inpatient-days. The team collected stool specimens from 32% (n = 53) of the patients, 23% (n = 12) of which had laboratory-confirmed C difficile infections (12.3 cases per 10,000 inpatient-days).

For the data on long-term care facilities residents, there were 63 patients with new-onset diarrhea, accounting for 10,402 resident-days (0.6 per 100 long-term care facility resident-days).

The investigators collected stool specimens from 32% (n = 20) of these patients, 45% (n = 9) of which had laboratory-confirmed CDI (8.6 cases per 10,000 long-term care facility resident-days).

“New-onset diarrhea was common among inpatients and LTCF-residents,” the authors wrote. “Only one-third of patients with new-onset diarrhea had a stool specimen collected and tested for C. difficile—indicative of a potential for CDI underdiagnosis—although further studies are needed to confirm the extent of CDI underdiagnosis.”


The investigators did identify some limitations associated with the study. For example, the study was conducted over a relatively brief study period, which was different for each participating hospital. The investigators also did not account for potential seasonal variations, which means the results may not represent a full calendar year.

The study, “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,” was published online in the International Journal of Infectious Diseases.