Impact of a real-time diagnostic and antimicrobial stewardship workflow on time to appropriate therapy for infections caused by multidrug-resistant Gram-negative organisms.

INTRODUCTION: Multidrug-resistant (MDR) Gram-negative organisms cause life-threatening infections, and the incidence is rising globally. Timely therapy for these infections has a direct impact on patient survival. This study aimed to determine the impact of a multidisciplinary diagnostic and antimicrobial stewardship (AMS) workflow on time to appropriate therapy (TAP) for these infections using novel beta-lactam/beta-lactamase inhibitors. METHODS: This was a retrospective quasi-experimental study of adult patients with carbapenem-resistant Enterobacterales (CRE) and multidrug-resistant Pseudomonas (MDR PsA) infections at a 1500 bed university hospital. Included patients who received ≥ 72 hours of ceftazidime-avibactam (CZA) or ceftolozane-tazobactam (C/T) from December 2017 to December 2019. During the pre-intervention period (December 2017 to December 2018), additional susceptibilities (including CZA and C/T) were performed only upon providers' request. In 2019, reflex algorithms were implemented for faster identification and testing of all CRE/MDR PsA isolates. Results were communicated in real-time to the AMS team to tailor therapy. RESULTS: A total of 99 patients were included, with no between-group differences at baseline. The median age was 60 years and 56 (56.7%) were in intensive care at the time of culture collection. Identified organisms included 71 (71.7%) MDR PsA and 26 CRE, of which 18 were carbapenemase producers (Klebsiella-producing carbapenemase = 12, New Delhi metallo-ß-lactamase = 4, Verona integron-encoded metallo-ß-lactamase = 2). The most common infections were pneumonia (49.5%) and bacteraemia (30.3%). A decrease was found in median TAP (103 [IQR 76.0-156.0] vs. 75 [IQR 56-100] hours; P < 0.001). Median time from culture collection to final susceptibility results was shorter in the post-intervention group (123 vs. 93 hours; P < 0.001). CONCLUSION: This study identified improvement in TAP in MDR PsA and CRE infections with implementation of a reflex microbiology workflow and multidisciplinary antimicrobial stewardship initiatives.

Implementing carbapenem-resistance testing algorithms for Enterobacteriales and Pseudomonas aeruginosa: diagnostic and antimicrobial stewardship with timely infection prevention.

Early detection of carbapenem resistance in Gram-negative (CRGN) infections can help tailor therapy sooner and prevent horizontal transmission more efficiently. This involves timely, multidisciplinary communication. To this aim, we describe our experience with implementing reflex testing algorithms for expanded antibiotic susceptibilities and molecular mechanisms of resistance in a large academic hospital.