C. diff colonization more common in patients living near livestock

Testing for Clostridioides difficile at one Wisconsin hospital found higher risk for colonization among hematology-oncology patients but an association of residential proximity to livestock farms and colonization only among patients admitted to other units.

Patients who lived near livestock farms were more likely to be colonized with Clostridioides difficile at hospital admission, according to a recent study.

The retrospective cohort study included 3,043 patients admitted to a teaching-affiliated hospital in Milwaukee, Wisc., from May 1, 2017, to June 30, 2018 (51.4% women, 68.9% white, mean age of 62.0 years). All were screened at admission for C. diff using a nucleic acid amplification test. Results were published by JAMA Network Open on Jan. 10.

At admission, 318 patients (10.4%) were found to be C. diff carriers. Slightly fewer than a third of study patients (32.1%) were admitted to hematology-oncology units, and multivariable logistic regression analysis showed that they were 35% more likely to be colonized with C. diff than patients admitted to other units. The study found no significant associations between colonization and hematology-oncology patients' sociodemographic and economic characteristics or health care and environmental exposures.

However, among patients admitted to other units, colonization was significantly more common in those who had comorbidities (odds ratio [OR] with one or two vs. no comorbidities, 4.17; 95% CI, 1.22 to 14.23), who were women (OR, 1.59; 95% CI, 1.03 to 2.46), and who had been hospitalized in the preceding six months (OR, 1.66; 95% CI, 1.06 to 2.61). In addition, patients who lived closer to livestock farms had a significantly higher likelihood of a positive C. diff test result (OR per mile from farm, 0.67; 95% CI, 0.49 to 0.90).

The study authors noted that a number of risk factors for C. diff colonization at hospital admission have been identified by previous research, including recent hospitalization, corticosteroid use, and previous C. diff infection. However, to their knowledge, this is the first evaluation of environmental sources. Research has shown that farmers of animals colonized with C. diff are more likely to carry C. diff themselves, the authors noted.

“In addition to previously considered risk factors (eg, previous hospitalization), our analysis indicates that residential proximity to certain environmental exposures, such as livestock farms, is associated with a higher risk of C difficile carriage, particularly among the non–hematology-oncology population,” the study authors concluded. “This environmental association might be owing not only to higher exposure to C difficile but also to exposure to microbiome disruptors, such as antibiotics and pesticides in water runoff.”

They suggested that this newly discovered association could be used to better tailor measures to prevent C. diff infection. The study was limited because it took place at a single center and did not explore the variables of outpatient antibiotic exposure, chemotherapy, or medical procedures, the authors noted.