The incidence of Clostridium difficile infection (CDI) has tripled over the past decade despite most hospitals making CDI prevention and transmission a top priority. Considering the magnitude of the epidemic, efforts are being made to increase the use of new, highly sensitive polymerase chain reaction (PCR) testing to diagnose CDI. “Use of PCR is expected to increase and has the potential to help identify populations and sub-populations that are at highest risk of CDI due to increasing sensitivity,” explains Sara Yee Tartof, PhD, MPH.

CDI: From Hospital to Community

To describe the incidence rates of PCR-diagnosed CDI, Dr. Tartof and colleagues analyzed data from about 270,000 patients aged 1 or older who were admitted to any of 14 Kaiser Permanente medical centers over a 2-year period. Unique to the study—which was published in Mayo Clinic Proceedings—is that it included positive PCR results that occurred in the outpatient setting in the 2 weeks after hospital discharge. “Most studies of hospital-acquired CDI only include infections that present prior to discharge,” Dr. Tartof notes, “and we found that this underestimates hospital-associated risk.”

Whereas most studies have found CDI to be a hospital-based infection of older, sick adults, Dr. Tartof and colleagues found that 80% of hospitalized patients who tested positive for CDI did so within 72 hours of hospitalization. Fewer than 2% of patients had at least one positive PCR test for CDI, but 49% of these individuals acquired their infection in the community or from an indeterminate source and 31% of cases were associated with a previous hospitalization. “Many patients are likely entering the hospital already infected,” she says. “While the hospital environment is still an important focal point for transmission of CDI, the community is likely playing a larger role in the CDI epidemic than previously thought.”

Assessing Risk for CDI

In the study, CDI was most common among Caucasians and women, and incidence rates increased with age. Dementia, connective tissue disease, rheumatic disease, and peripheral vascular disease were also associated with CDI. “People with high use of the healthcare system in the 12 months before an inpatient admission were also at increased risk for CDI,” adds Dr. Tartof.

More research is on the way that will adjust these findings on CDI risk based on a number of factors. “Caucasians may be more likely to come to the hospital from a skilled nursing facility, for example,” explains Dr. Tartof. “As such, their increased risk for CDI could be based on residence in addition to race.” A follow-up study will aim to develop a risk assessment tool to help determine which patients are most likely to acquire CDI. In the meantime, Dr. Tartof encourages clinicians to consider allocating resources for at-risk CDI cases based on the understanding that many patients enter the hospital already infected or develop symptoms after discharge.


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