Active Surveillance Cultures for Multidrug Resistant Gram-Negative Organisms at an Acute Care Hospital

This is a retrospective cross-sectional study of patients with ASC at MHS. Patients >18 years of age, admitted to MHS during the study specified period, will be included if there is documented ASC. Patients will be identified through the clinical microbiology laboratory records. Figure 1 is a flow diagram of ASC stratification.

Study populations All patients with documented laboratory surveillance culture from January 1, 2006 to December 31, 2012 will be included. Eligible cultures (see definitions below) will be identified based on positive surveillance cultures from MHS. Patients identified with select criteria per objective will be further analyzed in subsequent phases to complete all outcomes of interest. Patients will be excluded if they are ≤18 years, expired before initial surveillance culture is positive, were not admitted, or were transferred to another institution. Patients will be excluded if they underwent amputation or surgical revision for wound infections. Patients with polymicrobial MDR gram-negative pathogen on ASC will be included; however, the main focus of this study is the subset of patients with monomicrobial ASC. Lastly, only the index culture will be considered, for patients with multiple wounds ASC.

Data Collection Initial phase will focus on review of surveillance cultures within the past year (calendar year 2012) to determine objective number one. Prior years are included to evaluate earlier documentation of colonization and whether number of patients/cultures per year has significant variation. Subsequent phases will collect specific data identified as significant or varied based on previous analysis. Data will be collected via extraction and chart review from MHS's electronic medical record (EMR) on identified patients.

Patient demographics (weight, sex, race, age, allergy), co-morbid conditions (diabetes, immunosuppressed, HIV/AIDS, organ transplant, malignancy, chronic lung disease, chronic kidney disease, liver disease, surgery in past 30 days), location in the hospital, type of residence (i.e., home, long-term care facility, etc), source of infection, treatment data (antibiotics administered and duration), length of stay in survivors, hospital cost, antibiotic cost, severity of illness by mean Simplified Acute Physiologic Score (SAPS) II score (based on clinical data present during the 24 hours preceding the index blood culture), hospital mortality, and DRG. Previous hospitalizations, antimicrobial usage and surveillance culture results will be recorded.

Surveillance cultures from nares, rectum, endotracheal aspirates, urine, and wound swab will be included. Microbiology data (organism, culture source, and number of classes of antibiotics with resistance) will be documented. Patients with positive ASC for MDR gram-negative pathogens will be evaluated for antimicrobial use for 1) ASC only and 2) Subsequent positive cultures due to suspected or proven active infection. Cost for each of the following classifications will be determined and compared: microbiological cultures including antimicrobial susceptibility test, length of stay, cost of antimicrobial and associated diagnosis related groups (DRG) per infection type.