Investigators Show That the Epidemiology of CDI is Changing

Clostridium difficile is the most common cause of nosocomial infectious diarrhea in the United States. However, recent reports have documented that C. difficile infections (CDIs) are occurring among patients without traditional risk factors. Jennifer L Kuntz, of the Center for Health Research at Kaiser Permanente Northwest in Portland, Ore. and colleagues at the University of Iowa, sought to examine the epidemiology of CA-CDI by estimating the incidence of CA-CDI and HA-CDI, identifying patient-related risk factors for CA-CDI, and describing adverse health outcomes of CA-CDI.

The investigators conducted a population-based, retrospective, nested, case-control study within the University of Iowa Wellmark Data Repository from January 2004 to December 2007. They identified persons with CDI, determined whether infection was community-associated (CA) or hospital-acquired (HA), and calculated incidence rates. They collected demographic, clinical, and pharmacologic information for CA-CDI cases and controls (i.e., persons without CDI). We used conditional logistic regression to estimate the odds ratios (ORs) for potential risk factors for CA-CDI.

The incidence rates for CA-CDI and HA-CDI were 11.16 and 12.1 cases per 100,000 person-years, respectively. CA-CDI cases were more likely than controls to receive antimicrobials (adjusted OR, 6.09 [95% CI 4.59-8.08]) and gastric acid suppressants (adjusted OR, 2.30 [95% CI 1.56-3.39]) in the 180 days before diagnosis. Controlling for other covariates, increased risk for CA-CDI was associated with use of beta-lactam/beta-lactamase inhibitors, cephalosporins, clindamycin, fluoroquinolones, macrolides, and penicillins. However, 27 percent of CA-CDI cases did not receive antimicrobials in the 180 days before their diagnoses, and 17 percent did not have any traditional risk factors for CDI.

The researchers conclude that their study documented that the epidemiology of CDI is changing, with CA-CDI occurring in populations not traditionally considered "high-risk" for the disease. Clinicians should consider this diagnosis and obtain appropriate diagnostic testing for outpatients with persistent or severe diarrhea who have even remote antimicrobial exposure. Their research was published in BMC Infectious Diseases.

Reference: Kuntz JL, Chrischilles EA, Pendergast JF, Herwaldt LA and Polgreen PM. Incidence of and Risk Factors for Community-associated Clostridium difficile Infection: a nested case-control study. BMC Infectious Diseases 2011, 11:194doi:10.1186/1471-2334-11-194