180. Multicenter Analysis of Adequacy of Empiric and Definitive Therapy by Time to Culture Result in Hospitalized Patients with Blood Culture Positive for Carbapenem Resistant and Susceptible Enterobacterales and Pseudomonas aeruginosa
Authors: Cooper Lauren , Van Benten Kayla , Yu Kalvin , Ai ChinEn , Patkar Anuprita , Gregory Sara , Gupta Vikas 
Published: November 2023

Abstract

Background
Rapid identification and antimicrobial susceptibility testing (AST) of pathogens causing bloodstream infections (BSI) is critical to providing accurate patient therapy. We conducted a multicenter evaluation of inadequate empiric (IET) and definitive therapy (IDT) from culture turn-around-time (TAT) in carbapenem susceptible (Carb-S) and carbapenem non-susceptible (Carb-NS) Enterobacterales (ENT) and P. aeruginosa (PSA) from blood specimens.

Methods
Hospitalized adults (≥ 18 yo) with facility reported AST from 2018-2022 across 161 facilities in the BD Insights Research Database (Franklin Lakes, NJ) were identified for non-contaminant Carb-S and Carb-NS ENT and PSA from blood specimens. We evaluated antibacterial therapy as IET (from culture collection to prior to first AST result) and IDT (48-hours post first AST result and not discharged) by 12-hour increments of culture TAT (date/time first AST results minus date/time culture collection).

Results
In total, we identified 42,125 ENT of which 1.2% (525) were Carb-NS, and 3,750 PSA of which 11.3% (423) were Carb-NS. The median time to AST results (hrs.) was significantly longer in Carb-NS ENT vs. Carb-S ENT (73.0 vs. 60.0) and in Carb-NS PSA vs. Carb-S PSA (77.8 vs. 69.5; Table 1). Average IDT was significantly lower than IET in Carb-S ENT (2.0% vs. 6.2%), Carb-NS ENT (15.1% vs. 45.6%), Carb-S PSA (3.6% vs. 10.8%) and Carb-NS PSA (14.6% vs. 39.8%) pathogen results. IDT was lower than IET at each 12-hour increment of availability of AST results (Figures 2, 3). IDT was also lower than IET at each 12-hour increment of availability of AST results for Carb-S ENT and Carb-NS ENT (Figure 2) and Carb-S PSA and Carb-NS PSA (Figure 3). Overall IDT was 15.1% and 14.6% in Carb-NS ENT and Carb-NS PSA, respectively, and only 2.0% and 3.6% in Carb-S ENT and Carb-S PSA, respectively.Table 1.Characteristics for hospitalized adults with blood culture positive Enterobacterales (ENT) and P. aeruginosa (PSA).* p&lt;0.0001 for IDT vs. IET; ^ p &lt; 0.0001 for Carb-NS vs. Carb-S. Carb, carbapenem; IDT, inadequate definitive therapy (pathogen identified was not covered or was not susceptible to any antibiotics received from time of AST result until 48-hours later); IET, inadequate empiric therapy (pathogen identified not covered or was not susceptible to any antibiotics received from Day -2 until the time of AST result); NS, not susceptible; TAT, turn-around, time. * A patient’s admission can have both a Carb-S and Carb-NS pathogen.Figure 1.Cumulative TAT (hr.) for ENT, Carb-NS ENT, PSA and Carb-NS PSA in blood samples from hospitalized adult patients.Figure 2.Percent IET and IDT in ENT and Carb-NS ENT by AST TAT (hours)

Conclusion
The time it takes to obtain a pathogen identification and AST results for Carb-NS ENT and PSA organisms is longer than Carb-S ENT and PSA organisms, resulting in Carb-NS patients remaining on IET for extended periods of time. Additionally, since a higher percentage of Carb-NS patients never receive adequate targeted therapy, efforts to integrate diagnostic and antimicrobial stewardship can improve both timing of culture results and receipt of adequate therapy.Figure 3.Percent IET and IDT in PSA and Carb-NS PSA by AST TAT (hours)

Disclosures
Lauren Cooper, PhD, MPH, D(ABMM), AbbVie: Grant/Research Support|Becton Dickinson, Inc: Stocks/Bonds Kalvin Yu, MD, FIDSA, BD: Stocks/Bonds ChinEn Ai, MPH, Becton, Dickinson and Company: Employee Anuprita Patkar, PhD, BD: Grant/Research Support|BD: Stocks/Bonds Vikas Gupta, PharmD, Becton, Dickinson and Company (BD): Employee of BD|Becton, Dickinson and Company (BD): Stocks/Bonds