1794Appropriate Antibiotic Therapy is Associated with Reduced Risk of Community Acquired Clostridium difficile Infection

Background. Antibiotic exposure is an important andmodifiable risk factor forClostridium difficile infection (CDI).We hypothesized that appropriate antibiotic therapy for common outpatient infections might reduce the risk of community-acquired CDI (CA-CDI). Methods. We conducted a case-control study of independent-living adult outpatients for two ambulatory infectious diagnoses: urinary tract infection (UTI) and community-acquired pneumonia (CAP). We captured CA-CDI cases in Kaiser Permanente Northern California from 2007-2012 diagnosed within 90 days of outpatient treatment for UTI or CAP. We matched CDI cases with controls of similar age treated for the same infection at the same facility within 30 days of the cases (1:3 match for CAP [n = 205] and 1:2 match for UTI [n = 204]). We used multivariable logistic regression to explore the relationship between appropriate antibiotic treatment and CA-CDI risk while controlling for patient characteristics, specific antibiotic classes, stomach acid suppression, and recent history of additional antibiotic exposure. Results. Appropriate antibiotic treatment was associated with a 7fold decrease in the risk of CA-CDI among UTI patients (Odds Ratio [O.R.] = 0.13, 95% Confidence Interval [C.I.] 0.06-0.32, P <0.001) and a 3fold decrease in the risk of CA-CDI among CAP patients (O.R. = 0.34, 95% C.I. 0.17-0.68, P = 0.002). Similar results were found after controlling for other predictors in both the UTI population (O.R. = 0.11, 95% C.I. 0.03-0.41, P = 0.001) and the CAP population (O.R. = 0.20, 95% C.I. 0.08-0.51, P < 0.001). Other significant predictors of CA-CDI in the CAP group included use of moxifloxacin or use of multiple antibiotics. Other significant predictors of CACDI in the UTI group included underlying gastrointestinal diseases (e.g. diverticulitis) or procedures, stomach acid suppression, and recent history of additional antibiotic exposure. Conclusion. Appropriate antibiotic therapy is associated with significantly reduced CA-CDI risk. Adherence to established IDSA guidelines for outpatient antibiotic treatment decreases the risk of CA-CDI. Disclosures. I. Y. Ge, Kaiser Foundation Research Institute: Grant Investigator, Research grant