Epidemiological Assessment of the Association Between Antibiotic Consumption and Clostridium difficile Incidence at an Academic Medical Center

Background: Healthcare Facility-Onset Clostridium difficile infection (HO CDI), or CDI diagnosed beyond the first 3 calendar days following admission, is a major source of infectious disease-related morbidity and mortality in the U.S. The objective of the present study is to characterize the association between antibiotic consumption and the incidence of HO CDI.

Methods: A single-center, retrospective, ecologic study was conducted to evaluate the relationship between antibiotic consumption, measured in antibiotic days (ADs), and the incidence of HO CDI at our center between January 2013 and April 2015. CDI was tabulated using CDC National Healthcare Safety Network definitions for CDI, and antibiotic consumption was quantitated using the CDC Antibiotic Use (AU) module. Antibiotic consumption data with incomplete location mapping were excluded. Antibiotic use, standardized to 1000 days present, was correlated with HO CDI, standardized to 100,000 days present. Pearson correlation coefficients and linear regression were used to describe the relationship using matched months and one-month forward time lags.

Results: Facility-wide analysis identified a correlation between ceftriaxone and HO CDI from January 2013 to April 2015 (r=0.40, p=0.035, Fig 1). Unit-level analysis among patients in a single unit of predominantly stem cell transplant recipients did not show a significant correlation between carbapenems and HO CDI from January 2013 to September 2014 (r=0.29, p = 0.203). However, when a one-month forward lag was applied, carbapenem usage did show a significant correlation with HO CDI incidence in the same unit during the same timeframe (r=0.46, p=0.041, Fig 2).

Conclusion: Several facility-wide and unit-level associations were observed between antibiotic consumption and HO CDI. The one-month forward lag association of carbapenems with HO CDI contrasts with matched month correlations, as seen with ceftriaxone, and warrants replication at other sites and units. Furthermore, exploration of transmission routes, patients' baseline C. difficile colonization statuses, and timing of readmissions and disease onset is indicated.

Figure 1.

Figure 2.

Page Crew, PharmD, MPH, BCPS^1,2, Nathaniel Rhodes, PharmD, MSc^1,3, J. Nicholas O'donnell, PharmD^1,2, Cristina Miglis, PharmD, BCPS^1,2, Elise Gilbert, PharmD, BCPS^4,5, Teresa Zembower, MD, MPH, FIDSA⁶, Chao Qi, PhD⁷, Christina Silkaitis, MT (ASCP), CIC⁸, Sarah Sutton, MD⁶ and Marc Scheetz, PharmD, MSc, BCPS AQ-ID^1,3, (1)Pharmacy Practice, Midwestern University, Chicago College of Pharmacy, Downers Grove, IL, (2)Pharmacy, Northwestern Memorial Hospital, Chicago, IL, (3)Department of Pharmacy, Northwestern Medicine, Chicago, IL, (4)Northwestern Memorial Hospital, Chicago, IL, (5)Chicago State University College of Pharmacy, Chicago, IL, (6)Division of Infectious Diseases, Northwestern University Feinberg School of Medicine, Chicago, IL, (7)Pathology, Northwestern University Feinberg School of Medicine, Chicago, IL, (8)Healthcare Epidemiology and Infection Prevention, Northwestern University, Chicago, IL

Disclosures:

P. Crew, None

N. Rhodes, None

J. N. O'donnell, None

C. Miglis, None

E. Gilbert, None

T. Zembower, None

C. Qi, None

C. Silkaitis, None

S. Sutton, None

M. Scheetz, None

See more of: Clostridium difficile: Risk Factors
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