C. Diff Infection Diagnosis Increases Risk for Family Members

Aaron C. Miller, PhD

Having a family member with a Clostridium difficile (C. diff) infection (CDI) substantially increases the risk of acquiring an infection.

A team, led by Aaron C. Miller, PhD, Department of Epidemiology, University of Iowa, examined whether exposure to a family member with C. diff infections were linked to a greater risk of acquiring an infection in exposed individuals.

In the case-control study, the investigators examined 224,818 cases of infections representing 194,424 insurance plan enrollees. The investigators compared the incidence of infections among individuals with prior exposure to a family member with a C. diff to those without prior family exposure.

Each individual was binned into monthly enrollment strata based on exposure status such as family exposure and confounding factors including age and prior antibiotic use.

The team derived data from population-based, longitudinal commercial insurance claims using the Truven Marketscan Commercial Claims and Encounters and Medicare Supplemental databases from 2001-2017.

Eligible households had at least 2 family members continuously enrolled for at least 1 month.

Index CDI cases were identified using inpatient and outpatient diagnosis codes, with exposure risks 60 days prior to infection including CDI diagnosed in another family member, prior hospitalization, and antibiotic use.

The team sought primary outcomes of the incidence of C. diff infections in a given monthly enrollment stratum, with separate analyses considered for infections diagnosed in outpatient or hospital settings.

The investigators computed infection incidence within each stratum and used a regression model to compare incidence of C. diff infections while controlling for possible confounding characteristics.

Of the 194,424 enrollees occurring in families with at least 2 enrollees, the investigators identified 1074 CDI events occurred following a CDI diagnosis in a separate family member.

Ultimately, they found having a family member with a C. diff infection significantly raised the risk of acquiring an infection, even after controlling for other factors (IRR, 12.47; 95% CI, 8.86-16.97).

Prior family exposure represented the factor with the second highest IRR behind hospital exposure (IRR, 16.18; 95% CI, 15.31-17.10).

For community-onset cases without prior hospitalization, the IRR for family exposure was 21.74 (95% CI, 15.12-30.01), while age (IRR, 9.90; 95% CI, 8.92-10.98 for ages ≥65 years compared with ages 0-17 years), antibiotic use (IRR, 3.73; 95% CI, 3.41-4.08 for low-risk and 14.26; 95% CI, 13.27-15.31 for high-risk antibiotics compared with no antibiotics), and female sex (IRR, 1.44; 95% CI, 1.36-1.53) were also positively associated with incidence.

“This study found that individuals with family exposure may be at significantly greater risk for acquiring CDI, which highlights the importance of the shared environment in the transmission and acquisition of C difficile,” the authors wrote.

Recent data shows positive trends regarding C. diff infections and hospitalization within the last 10 years.

A team, led by Alice Y. Guh, MPH, identified cases of C. diff infections in stool specimens positive for C. diff in an individual at least 1 years old with no positive test in the previous 8 weeks in 10 US sites.

In the Emerging Infections Program, the investigators used case and census sampling weights to estimate the national burden of infections, first recurrences, hospitalizations, and in-hospital deaths between 2011-2017.

Overall, they identified 15,461 cases in 2011—10,177 healthcare-associated cases and 5284 community-associated cases. In 2017, they identified 15,512 cases—7973 healthcare-associated cases and 7539 community-associated cases.

The estimated national burden of infections was 476,400 (95% CI, 419,900-532,900) in 2011 and 462,100 cases (95% CI, 428,600-495,600) in 2017.

After accounting for NAAT use, the adjusted estimate of the total burden of C. diff infection decreased by 24% from 2011 through 2017 (95% CI, 6-36).

The adjusted estimate of the national burden of healthcare-associated cases decreased by 36% (95% CI, 24-54), while the adjusted estimate of the national burden of community-associated infections was unchanged.

The study, “Association of Household Exposure to Primary Clostridioides difficile Infection With Secondary Infection in Family Members,” was published online in JAMA Network Open.