Derivation of a Model to Guide Empiric Therapy for Carbapenem-Resistant Bloodstream Infection in an Endemic Area.

Background: Appropriate therapy for carbapenem-resistant (CRKP) bloodstream infection (BSI) is often given late in the course of infection, and strategies for identifying CRKP BSI earlier are needed.

Methods: A retrospective case-control study was performed at a tertiary care hospital, university hospital, and community hospital in Bronx, New York. All participants had a blood culture sent and received an antibiotic within 48 hours of the culture. The case group (n = 163) had a blood culture with CRKP. The control group (n = 178) had a blood culture with carbapenem-susceptible . Data were obtained by electronic or conventional medical record abstraction. A multiple logistic regression model was built to identify associated factors and develop a clinical model for CRKP BSI. Model performance characteristics were estimated using a 10-fold cross-validation analysis.

Results: A prior nonblood culture with carbapenem-resistant Enterobacteriaceae, skilled nursing facility (SNF) residence, mechanical ventilation, and admission >3 days were strongly associated risk factors. A significant interaction led to development of separate clinical models for subjects admitted <3 days at the time of positive blood culture from those admitted at least 3 days. The derived models had a good ability to discriminate between subjects with and without CRKP BSI. A clinical classification rule to guide therapy can prioritize sensitivity or specificity.

Conclusions: Prior nonblood cultures showing resistance and exposure to SNF and health care settings are factors associated with carbapenem resistance. The clinical classification rules derived in this work should be validated for ability to guide therapy.