Asymptomatic C. diff carriers contribute to nosocomial infection spread

Last Updated: 2017-01-17

By Anne Harding

NEW YORK (Reuters Health) - Asymptomatic carriers of Clostridium difficile may contribute to the spread of the infection in hospitals, according to new research.

"In a situation where nosocomial C. difficile infection is a significant problem despite e.g. isolation precautions and antibiotic stewardship one should consider to test the patients admitted for being asymptomatic carriers. If the load is high then one should consider isolation precautions among the carriers," Dr. Thomas Blixt of the University of Copenhagen, Denmark, one of the study's authors, told Reuters Health by email. The findings were published online January 5 in Gastroenterology.

C. difficile infection among hospitalized patients is on the rise, despite comprehensive efforts to reduce infection, Dr. Blixt and his team note. Infection control efforts that only target inpatients infected with C. difficile may not be adequate to prevent the spread of disease, they add. They point to one study that found these patients only contributed to a quarter of new infections.

To investigate whether asymptomatic carriers might be a source of new infections, the researchers performed a prospective cohort study over four months, including more than 4,500 hospital admissions.

Fecal samples were collected from patients within 48 hours of hospital admission to test for toxin-producing C. difficile. The researchers developed an index to measure "infectious pressure" based on patients' exposure to asymptomatic C. difficile carriers at the hospital room or ward level. They also incorporated length of hospital stay into their analysis.

Among 3,083 patients who were not exposed to C. difficile carriers, 2.6% tested positive for the infection, versus 4.6% of the 630 patients exposed at the room level, yielding an odds ratio of 1.79 (95% confidence interval, 1.16-2.76).

There was a significant relationship between quartiles of the infectious pressure index and the rate of infections. Patients in the lowest quartile had a 2.2% risk of C. difficile infection, while those in the top quartile had a 4.2% risk. Length of stay appeared to have an additive effect to exposure load on the risk of contracting the infection.

"We want to perform further analysis on the cohort e.g. differences in medication between the groups. It would also be interesting to examine if asymptomatic carriers have an increased mortality compared to the other patients in the cohort," Dr. Blixt said.

"It is important primarily to focus on the isolation precautions among the symptomatic cases of C. difficile infection and to have focus on antibiotic stewardship," he added. "Screening for asymptomatic carriers should in our opinion only be considered if the incidence of nosocomial C. difficile infection is a persisting issue in spite of optimization of the isolation procedures and antibiotic stewardship."

SOURCE: http://bit.ly/2jrtt7R

Gastroenterology 2017.