We are responding to RFA-CK-18-001. The long-term goal of this application is to identify novel strategies for healthcare associated infections (HAI) prevention. The overall objective of this application is to advance the surveillance of HAIs and appropriately guide infection prevention activities to improve healthcare quality and patient safety. This application includes two separate studies as follows: Study 1: The overall objective of the hospital onset-bacteremia (HOB) study is to advance the study of HOB as a surveillance metric and potential quality measure of HAI by evaluating sources and preventability of HOB. The specific aims are as follows: 1. Assess the sources and preventability of HOB through a detailed expert review of a large number of HOB events in a set of geographically diverse academic and community hospitals a. Develop a standardized assessment tool using a Delphi method/expert panel approach to determine preventability of HOB b. Conduct chart reviews to identify sources of HOB c. Determine preventability of HOB using the standardized preventability assessment tool developed above 2. Estimate the ?preventable fraction? of HOB as a function of patient, isolate, and facility characteristics to identify the subset of HOB that are most suitable for an HAI quality metric 3. Provide subject matter expertise to CDC on a parallel CDC-led analysis evaluating the magnitude and variability in HOB among a large number of US hospitals using existing CDC datasets. Study 2: The overall objective of the C. difficile infection (CDI) study is to advance risk adjustment of CDI by incorporating comorbid conditions into the risk adjustment model and determining the feasibility of adding comorbid conditions to data collection on a national scale. The specific aims are as follows: 1. Determine which electronically-available ICD-10 codes can be used to better risk adjust CDI. 2. Determine the feasibility and time needed to submit all ICD-10 data among all hospitalized patients to federal agencies such as the CDC or CMS. In the long term, the outcomes from Study 1 will form the basis of prevention of bloodstream infections not addressed by current HAI prevention efforts. Outcomes from Study 2 will improve risk adjustment for CDI and through risk-adjusted rates, help identify more appropriate targets for CDI reduction. Therefore, this application through improvement in HAI surveillance, supports development of innovative strategies for preventing HAIs.