SAN DIEGO – Delays in laboratory testing led a hospital to misclassify the origin of nearly a quarter of Clostridium difficile infections, Dr. Christopher Polage said at an annual scientific meeting on infectious diseases.
“Many patients with symptoms and risk factors are not being tested within 3 days of admission, leading to overreporting of hospital-onset [Clostridium difficile infections] and underreporting of community-onset CDI,” said Dr. Polage of the UC Davis (Calif.) Health System. By testing patients who have diarrhea and risk factors for CDI sooner after admission, hospitals can prevent outbreaks and improve their standardized infection ratio for CDI, he added.
CDC/D. Holdeman
Clostridium difficile is implicated in about 29,000 deaths every year in the United States. The vast majority of such cases are classified as hospital onset, based on the “3-day rule,” meaning that patients were tested more than 3 days after admission. “This is the preventable hospital outcome that we’re all trying to bring down,” Dr. Polage said.
As part of that effort, he and his colleagues studied 11 hospital units that were considered high risk for CDI. To identify toxigenic C. difficile, they performed culture and polymerase chain reaction testing on perianal swabs collected from all adult patients admitted to these units. They also analyzed toxin immunoassays of stool samples when physicians requested them for patients with diarrhea.
“The question was, how often was misclassification happening?” said Dr. Polage. Among 48 cases that the laboratory reported as hospital onset, based on the “3-day rule,” close to half (44%) actually had CD-positive perianal swabs when admitted, he said. And half of these swab-positive patients waited more than 3 days for a CD stool test even though they had current or recent diarrhea, he added. In fact, swab-positive patients with diarrhea went a median of 6 days without a CD stool test, and some went untested for 10 days, Dr. Polage said.
“Anyone who has tried to determine if a hospitalized patient is having diarrhea knows that this can be very hard to pin down,” Dr. Polage noted. But some patients with positive swabs on admission met three different definitions for diarrhea, “making it pretty clear that they had community-onset CDI,” he said. This most conservative approach found that 23% of “hospital-onset” cases were actually community onset, he said.
Thus far, UC Davis Health System seems not to have had an increase in antibiotic prescriptions in response to greater detection of community-onset CDI, Dr. Polage said. “This is not something we take lightly,” he added. “We put together a lot of educational materials for patients, physicians, and providers, and work with our antibiotic stewardship team. We found that we might be able to focus on patients who had CDI at time of admission, and intervene with them individually to more carefully monitor what antibiotic they were using.”
Dr. Polage reported these findings at IDWeek, the combined annual meetings of the Infectious Diseases Society of America, the Society for Healthcare Epidemiology of America, the HIV Medicine Association, and the Pediatric Infectious Diseases Society.
The Gordon and Betty Moore Foundation helped fund the study. Dr. Polage reported having received research materials or honoraria from Cepheid, TechLab, Alere, Meridian, and ACEA Biosciences.