Asymptomatic Carriers of C. Diff May Be Significant Source of Infection at Hospitals

“It has generally been assumed that patients get the bacteria during their stay in the hospital. However, when we tested patients being admitted to the hospital, we found that many of them were carrying the bacteria that causes this diarrhea in their bodies already and often went on to develop the infection,” Sarah Baron, MD, MS, director of Inpatient Quality Improvement in the Department of Medicine at Montefiore Health System, said in a prepared statement.

C. diff screening results

The research was conducted on 220 asymptomatic patients at Montefiore Medical Center in Bronx, New York.

The researchers focused mainly on patients from skilled nursing facilities based on earlier studies that had identified SNF residents at high risk for C. diff infection. Of the 220 patients enrolled in the study, 76% were nursing facility residents. All of the patients enrolled in the study were identified for C. diff screening within 24 hours of hospital admission.

The study generated several key data points:

• 21 or 9.6% of the patients screened positive as asymptomatic carriers of C. diff
• 10.2% of nursing facility residents and 7.7% of the community residents screened positive as asymptomatic carriers of C. diff
• 8 or 38.1% of the asymptomatic carriers progressed to symptomatic C. diff infection within six months
• For most of the asymptomatic carriers of C. diff who progressed to symptomatic C. diff infection, the progression process was less than two weeks from enrollment in the study
• Among the 199 noncarriers of C. diff, only 4 or 2.0% developed symptomatic C. diff infection within six months

“These findings might mean that we can predict who will develop C. diff and try to stop it before it starts. More work is needed to determine how we can protect everyone, even the patients who already have the bacteria in their colons, from developing this dangerous form of diarrhea,” Baron said.

Interpreting the data

Identifying asymptomatic carriers of C. diff could help hospitals address the spread of C. diff infections in two ways, Baron and her co-authors wrote. “First, isolation of C. difficile carriers could reduce transmission to uninfected patients, and second, interventions targeting C. difficile carriers could potentially prevent progression to symptomatic C. difficile.”

The finding that 38.1% of the asymptomatic carriers progressed to symptomatic C. diff infection (CDI) means that asymptomatic carriers could be a significant source of CDI in the hospital setting, Baron and her co-authors wrote. “Due to the high rate of progression, it is possible that a substantial proportion of “healthcare-facility onset” C. difficile may actually result from the progression from C. difficile carriage to symptomatic C. difficile, especially within the first two weeks of hospitalization.”

Baron and her co-authors called for more research on asymptomatic carriers of C. diff.

“Asymptomatic carriers may represent a significant reservoir for transmission of C. difficile, and progression from asymptomatic carriage to symptomatic CDI may account for a significant proportion of CDI that is classified as ‘healthcare-facility onset.’ Therefore, identification of asymptomatic carriers could reduce the spread of C. difficile.”