Impact of a Laboratory-Developed Phenotypic Rapid Susceptibility Test Directly From Positive Blood Cultures on Time to Narrowest Effective Therapy in Patients With Gram-Negative Bacteremia: A Prospective Randomized Trial

Abstract

Background Antimicrobial susceptibility testing is often needed prior to antimicrobial optimization for patients with Gram-negative bloodstream infections (GN-BSI). Rapid AST (rAST) in combination with antimicrobial stewardship (AS) may decrease time to administration of narrower antibiotics. Methods This was a prospective, non-blinded, randomized trial evaluating the impact of a phenotypic rAST method versus conventional AST (cAST) in hospitalized patients with GN-BSI and source control. The primary outcome was time to narrowest effective therapy. Results 274 patients were randomized and 205 underwent analysis (97 cAST, 108 rAST). Time to susceptibility results was 23 hours shorter in rAST group (cAST: 62 [59, 67] vs rAST: 39 [35, 46] hours; P < .001). The median (IQR) time to narrowest effective therapy was similar between groups (cAST: 73 [44, 138] vs rAST: 64 [42, 92] hours; P = .10). Time to narrowest effective therapy was significantly shorter in a pre-specified subgroup of patients not initially on narrowest therapy and during AS working hours (cAST: 93 [56, 154] vs rAST: 62 [43, 164] hours; P = 0.004). Significant decreases were observed in time (hours) to oral therapy (cAST: 126 [76, 209] vs rAST: 91 [66, 154]; P = 0.02) and median length (days) of hospital stay (LOS) (cAST: 7 [4, 13] vs rAST: 5 [4, 8] days; P = 0.04). Conclusion In patients with GN-BSI, rAST did not significantly decrease time to narrowest effective therapy but did decrease time to oral antibiotics and LOS. Rapid AST using existing microbiology platforms has potential to optimize patient outcomes.

Management of Bacterial and Fungal Infections in the ICU: Diagnosis, Treatment, and Prevention Recommendations

“… 57–59 For example, one study randomised positive blood cultures from patients with Gram-negative bacteraemia to undergo conventional versus rapid AST testing using an automated commercial method with a primary end point of time to narrowest effective therapy. 59 Rapid AST did not impact time to narrowest effective therapy but did significantly decrease time to oral antimicrobial switch and shortened length of hospital stay by two days. 59 …”

“… 59 Rapid AST did not impact time to narrowest effective therapy but did significantly decrease time to oral antimicrobial switch and shortened length of hospital stay by two days. 59 …”

Performance of the Vitek 2 Advanced Expert System (AES) as a Rapid Tool for Reporting Antimicrobial Susceptibility Testing (AST) in Enterobacterales from North and Latin America

“…It is recognized that patients infected with resistant pathogens are more likely to receive ineffective empirical antibiotic therapy, which is associated with poor outcomes, including death ( 6 – 10 ). On the other hand, the use of broad-spectrum therapies for the empirical treatment of serious infections may promote further selection of antimicrobial resistance, increased toxicity, and higher costs of care ( 11 , 12 ). In this respect, AST could provide a prediction of the likelihood of an antimicrobial’s clinical success and allow the emergence and spread of resistant microorganisms to be monitored ( 2 ).…”

Identificación y sensibilidad antibiótica de bacilos Gram negativos directamente del hemocultivo positivo

“…Los métodos microbiológicos de rutina de los laboratorios hospitalarios pueden tardar 48-72 horas en obtener la identificación y la sensibilidad antibiótica desde la alerta de positividad de la botella del hemocultivo 2 . La obtención de resultados rápidos de identificación y sensibilidad antibiótica podrían acortar el tiempo para el inicio de una terapia adecuada 3 . El objetivo del estudio fue determinar la concordancia de la identificación y sensibilidad antibiótica directa de la botella de hemocultivo, positivo para bacilos Gram negativos, utilizando el sistema Vitek 2 con la metodología estándar a partir de colonias en subcultivo.…”