Facility-level antibiotic use associated with C. difficile rates in long-term care

Facility-level antibiotic use and transfers of infected patients from acute care are drivers of Clostridium difficile infection in long-term care facilities, a study found.

Researchers sought to obtain a comprehensive picture of C. difficile incidence and risk factors in acute and long-term care using a case-cohort study of patients spending at least three days in one of 131 acute care or 120 long-term Veterans Health Administration facilities between 2006 and 2012.

Eight individual-level risk factors were assessed: sex, age, Charlson comorbidity count, acute care stay, long-term care stay, antibiotic exposure, antibiotic risk index, and proton-pump inhibitor (PPI) exposure. Facility factors included mean antibiotic use, mean PPI use, mean patient age, mean facility census, and importation (i.e., colonized or infected patients moved from outpatient settings). The study outcome was facility-onset, laboratory-identified C. difficile infection, defined as a person with a positive C. difficile test without a positive test in the previous eight weeks. Results were published by Clinical Infectious Diseases on June 8.

The study included 35,754 case-days of C. difficile, of which 28,615 (80%) were diagnosed during acute care stays and 7,139 (20%) were diagnosed during long-term care stays. Most of the studied individual-level variables, including male sex, comorbidity count, and pharmaceutical risk factors, were associated with C. difficile infection in both acute and long-term care, but the magnitude tended to be larger in long-term care, the study found.

A recent history of acute care exposure was a common (64.5% of cases and 27.3% of controls) and strong risk factor for C. difficile among long-term care patients (relative risk [RR], 4.84; 95% CI, 4.34 to 5.41). Among acute care patients, a history of long-term care exposure was a relatively rare (7.4% of cases and 4.0% of controls) and moderate risk factor for infection (RR, 1.89; 95% CI, 1.75 to 2.05).

C. difficile infection incidence was five times higher in acute care than in long-term care (median, 15.6 vs. 3.2 per 10,000 person-days). History of antibiotic use was greater in acute care compared to long-term care (median, 739 vs. 513 per 1,000 person-days) and explained 72% of the variation in C. difficile rates. Individual-level antibiotic use in acute care and in long-term care was strongly associated with risk (incidence rate ratios [IRR], 3.16 and 4.40, respectively),

In long-term care, facility-level importation of acute care cases (IRR, 1.35 per increase of 100; 95% CI, 1.18 to 1.53) and facility-level antibiotic use (IRR, 1.20 per increase of 100; 95% CI, 1.02 to 1.41) contributed to C. difficile infection risk. In the acute care model, facility-level importation of long-term care cases was associated with risk (IRR, 1.88 per increase of 100; 95% CI, 1.19 to 2.96) while facility-level antibiotic use was not (IRR, 0.88 per increase of 100; 95% CI, 0.70 to 1.12). Importation of C. difficile cases was three times higher in long-term care than in acute care (median, 52.3 vs. 16.2 per 10,000 person-days).

“We have shown the potential for inter-facility transmission of C. difficile infection, and that long-term care facilities disproportionately shoulder the burden of dealing with C. difficile cases from acute care, rather than vice versa,” the authors wrote. “This suggests that it may be wise for health care systems to coordinate infection control practices, so that appropriate infection prevention and control strategies are put into place for incoming patients and long-term care residents with histories of C. difficile infection.”