A prognostic score for the resolution of bacteremia by Gram-negative bacteria resistant to carbapenems

The management of bacteremia by carbapenem-resistant Gram-negative bacteria (CRGNB) necessitates a surrogate marker for response to treatment. We developed a prognostic score of bacteremia resolution using a test and a validation cohort. In the test cohort, five protein biomarkers were measured in serial daily serum samples from 39 patients with ventilator-associated pneumonia (VAP) and CRGNB bacteremia. Receiver operator characteristic curves were designed to identify cut-off of over-time changes that were associated with more than 80% specificity for resolution of bacteremia. The developed score was validated in a cohort of 24 patients mostly with primary bacteremia by carbapenem-resistant enterobacteria (CRE). Among the five tested biomarkers, only procalcitonin (PCT) was associated with resolution of bacteremia. More precisely, resolved bacteremia was considered if at least one of three situations occurred: (a) PCT on day 2 was decreased more than 30% and PCT on day 4 was below 0.5 ng/ml; (b) PCT on day 4 was decreased more than 40% and PCT on day 4 was below 0.5 ng/ml; and (c) PCT on day 2 was decreased more than 30% and PCT on day 4 was decreased more than 40%. Sensitivity, specificity, and positive and negative predictive values of the score were 66.7%, 83.3%, 90.0%, and 52.6% respectively. This score was fully validated (p values of comparison between the cohorts 0.623). The developed score is highly predictive of resolution of bacteremia by CRGNB. A prospective clinical study is mandatory to validate the results.