Obesity may be a risk factor for Clostridium difficile infection (CDI), according to results from a retrospective cohort study of 132 cases seen at a tertiary care medical center.

After potential confounders were taken into account, patients with simple community-onset infections were more than 4 times as likely to be obese as patients who had community-onset infections that came shortly after an exposure to a healthcare facility, according to data reported in an article published in the November issue ofEmerging Infectious Diseases.

“Obesity may be associated with CDI, independent of antibacterial drug or health care exposures,” write the researchers, led by Jason Leung, MD, from the University of Michigan Hospital in Ann Arbor. Such an association could help explain the uptick of community-onset cases in individuals having low levels of traditional risk factors.

The authors propose that obesity may perturb the intestinal microbiome in ways similar to those seen with inflammatory bowel disease and use of antibiotics, both of which are known risk factors for CDI.

“Translational research could help elaborate the dimensions of the interaction of the intestinal microbiota with C. difficile in obese patients,” the researchers maintain. They also suggest that an investigation of a dose–response relationship between body mass index and infection risk might be informative.

“[I]t is critical to establish whether obesity is a risk factor for high rates of C. difficile colonization, as is [inflammatory bowel disease]; if that risk factor is established, prospective observations would improve understanding of whether obesity plays a role in the acquisition of CDI, or alters severity of disease and risk for recurrence,” they write.

As for the patients with community-onset infections after healthcare exposure, the study’s findings highlight “the importance of increased infection control at ancillary health care facilities and surveillance for targeting high-risk patients who were recently hospitalized.”

In the study, the researchers reviewed the microbiology results and medical records of all patients who had laboratory-proven, nonrecurrent CDI at Boston Medical Center in Massachusetts during a 6-month period.

When the patients were classified according to the setting of disease onset, 43% had infections that began in the community without recent exposure to a healthcare facility, 30% had infections that began in a healthcare facility, and 23% had infections that began in the community within 30 days of exposure to a healthcare facility (most often a hospital or long-term care facility).

The prevalence of obesity, defined as a body mass index exceeding 30 kg/m², was 34% in the group with community-onset infections compared with 23% in the general population (odds ratio, 1.7; 95% confidence interval [CI], 1.02 – 2.99). The value stood at 13% in the group with community-onset healthcare-associated infections and 32% in the group with healthcare-onset infections.

In multivariate analyses, patients with simple community-onset infections were significantly less likely to be older than 65 years (odds ratio, 0.35; 95% CI, 0.13 – 0.92; P < .05) and more likely to be obese (odds ratio, 4.06; 95% CI, 1.15 – 14.36; P < .05) than patients with community-onset healthcare-associated infections.

In addition, patients with simple community-onset infections were significantly less likely to have prior antibiotic exposure (odds ratio, 0.29; 95% CI, 0.11 – 0.76; P < .05) than patients with healthcare-onset infections. There was also a trend whereby they were much more likely to have inflammatory bowel disease (odds ratio, 6.40; 95% CI, 0.73 – 56.17; P < .10).

Finally, patients with community-onset healthcare-associated infections were dramatically less likely to have had prior antibiotic exposure than patients with healthcare-onset infections (odds ratio, 0.08; 95% CI, 0.02 – 0.28; P < .05).