A recently published study documents the findings, reporting that CDIs in 10 Centers for Disease Control and Prevention (CDC) surveillance sites fell in hospitals but increased in the community.¹ There were 15,461 CDIs at these surveillance sites in 2011, including 10,177 healthcare-associated infections (HAIs) and 5,284 community-associated cases. The overall numbers in 2017 were similar in total, but the HAIs dropped to 7,973 and the community cases increased to 7,539. Hospital Infection Control & Prevention spoke to Alice Guh, MD, the lead author of the paper and a medical officer at the CDC.

HIC: You report that the estimated hospital burden of C. difficile infection in the United States declined from 2011 through 2017, despite the increasing use of the more sensitive nucleic acid amplification tests (NAAT). Can you elaborate on this finding?

Guh: NAAT has greater sensitivity for C. difficile than other diagnostic assays. Therefore, we would expect an associated increase in the incidence of CDI with increasing use of NAAT. However, we found the opposite result. Based on data reported from the [CDC] Emerging Infections Program, the percentage of all cases diagnosed by NAAT increased from 55% in 2011 to 84% in 2016, with a slight decrease to 83% in 2017. Despite the increase in NAAT use over much of this period, the national burden estimate of healthcare-associated CDI decreased from 306,500 in 2011 to 235,700 in 2017. Moreover, when NAAT use was held constant at 55% over this period, we observed a significant decrease in the adjusted national burden estimate of healthcare-associated CDI, supporting a true decline in CDI.

HIC: You report that C. difficile was reduced as adjusted 6% annually. What does this mean the total percentage reduction was over 2011 through 2017 period?

Guh: The adjusted burden estimate of healthcare-associated CDI decreased annually by 6%, resulting in a 36% decrease between 2011 and 2017.

HIC: Could this be some kind of surveillance artifact, or do you believe these are real reductions in patient infections?

Guh: Laboratories serving the surveillance catchment areas report all positive C. difficile test results to the Emerging Infections Program staff and are audited at least annually to ensure cases are not missed. Therefore, it is not likely that our results are due to under-reporting. However, with the increasing emphasis on diagnostic stewardship to reduce inappropriate testing, it is possible that fewer C. difficile tests have been ordered over time, which could have partly contributed to the decreased rates of healthcare-associated CDI. Nonetheless, I think adherence to recommended infection prevention measures also played a role, and our results likely reflect a real reduction in CDI burden.

HIC: What can you ascribe this reduction to? Is there any way to measure the effect of the increasing emphasis on antibiotic stewardship? For example, you cite the association between fluoroquinolones and C. difficile.

Guh: Several factors likely contributed to the reduction in healthcare-associated CDI, including increased attention to diagnostic stewardship to reduce inappropriate testing; implementation of antibiotic stewardship interventions, particularly those targeting fluoroquinolone use; and increased adherence to recommended infection prevention measures. Our analysis was not designed to measure the effect of antibiotic stewardship on CDI rates.

HIC: You and the co-authors noted that adherence to recommended infection-prevention practices may also have decreased HAIs, as shown by several successful local and regional initiatives for the prevention of C. difficile infection. Can you elaborate on this and give an example of a successful infection control intervention?

Guh: Local or regional CDI prevention initiatives have included a number of different interventions, ranging from the use of standardized infection prevention and environmental cleaning protocols to receiving onsite assessments of antimicrobial stewardship. A key factor for the success of these initiatives is the sharing of knowledge and strategies and lessons learned through regular discussions among participating facilities (e.g., monthly teleconferences).

HIC: Does the lack of decline in community C. diff mean that more infections will continue to be introduced by hospitalized patients? Does this community reservoir pose an ongoing threat to hospital success?

Guh: The lack of decline in community-associated C. difficile could potentially affect the burden of healthcare-associated CDI through importation of C. difficile into hospitals. According to unpublished CDC data, approximately 30% of patients hospitalized with CDI are community-associated.

HIC: While a direct foodborne link has not been established, toxigenic C. difficile has been cultured from retail meat and vegetables. Is it thought C. difficile can remain viable after food is cooked? Is the CDC actively looking at this potential source?

Guh: Although prior studies have indicated that C. difficile spores can survive cooking of meat and other foods, to date, there have been no known foodborne outbreaks associated with CDI. We have conducted a case-control study to identify potential risk factors for community-associated CDI and did not find any significant association with consumption of various food types, including red meat, poultry, or fresh vegetables. In this same case-control study, approximately 14% of patients with community-associated CDI had no recent antibiotic use or outpatient healthcare exposures, suggesting that they might have had another source of exposure or risk factor for CDI.

REFERENCE

1. Guh AY, Mu Y, Winston LG, et al. Trends in U.S. burden of Clostridioides difficile infection and outcomes. N Engl J Med 2020;382:1320-1330.