A novel test provides rapid bacterial identification and susceptibility results from positive blood cultures, shortening the time to antibiotic therapy and reducing unnecessary antibiotic exposure in hospitalised patients with bacteraemia, according to a study in the Journal of Antimicrobial Chemotherapy.
The Improving Outcomes and Antibiotic Stewardship for patients with gram-positive bloodstream infections (IOAS) study, led by scientists from Accelerate Diagnostics, evaluated clinical and antimicrobial stewardship metrics at two US hospitals, following implementation of the Accelerate PhenoTest BC Kit (AXDX), a diagnostic platform that can identify bacteria from blood cultures and provide antimicrobial susceptibility testing (AST) results up to 40 hours faster than conventional methods.
The researchers analysed two groups of patients with gram-positive bacteraemia, one that underwent traditional identification and AST (pre-AXDX) and one that underwent testing with AXDX (post-AXDX). The primary outcome was time to optimal therapy (TTOT), and secondary outcomes included time to first antibiotic modification (overall and gram-positive antibiotics) and duration on unnecessary coverage for methicillin-resistant Staphylococcus aureus (MRSA).
A total of 219 patients with gram-positive bacteraemia (109 pre-AXDX and 110 post-AXDX) were included in the study. The median TTOT was 36.3 hours in the pre-AXDX group and 20.4 hours in the post-AXDX group. Analysis of secondary outcomes showed that the median time to first antibiotic modification was also reduced in the post-AXDX patients (15.9 hours vs 29.1 hours), as was the median time to first gram-positive antibiotic modification (17.2 hours vs 33.2 hours) and the median duration of unnecessary MRSA coverage (29.7 hours vs 58.4 hours).
The researchers also observed a trend toward decreased acute kidney injury in the post-AXDX group compared with the pre-AXDX group (13% vs 24%) but found no differences in clinical outcomes such as mortality, Clostridioides difficile infection (CDI), and readmission to the hospital.
"In summary, implementation of AXDX offered a comprehensive solution to replace various identification and phenotypic testing methods and had a meaningful impact on the management of patients with Gram-positive bacteraemia in the IOAS study," the study authors wrote. "TTOT and initial antibiotic modifications were significantly faster, and patients received less unnecessary antibiotic therapy compared with conventional microbiology diagnostics."
Improving outcomes and antibiotic stewardship (IOAS) for patients with Gram-positive bloodstream infections through use of rapid testing: a quasi-experimental multicentre study of the Accelerate PhenoTest™ BC Kit
Authors: Shawn H MacVane, Amira A Bhalodi, Ryan K Dare, Eric R Rosenbaum, Kaleb Wolfe, Bradley Ford, Dilek Ince, Patrick Kinn, Kelly M Percival, Romney M Humphries
Published in Journal of Antimicrobial Chemotherapy on 22 May 2021
Data from the Improving Outcomes and Antibiotic Stewardship for Patients with Bloodstream Infections: Accelerate PhenoTest™ BC Kit (AXDX) Registry Study were analysed to determine the impact of rapid organism identification and antimicrobial susceptibility testing (AST) for Gram-positive bacteraemia.
Patients and methods
This multicentre, quasi-experimental study evaluated clinical and antimicrobial stewardship metrics following the implementation of AXDX. Data from hospitalized patients with bacteraemia were compared between groups, one that underwent testing on AXDX (post-AXDX) and one that underwent traditional identification and AST (pre-AXDX). An analysis of patients with Gram-positive bacteraemia was performed. The primary outcome was time to optimal therapy (TTOT). Secondary outcomes included time to first antibiotic modification (overall and Gram-positive), duration of unnecessary MRSA coverage, incidence of adverse events, length of stay and mortality.
A total of 219 (109 pre-AXDX, 110 post-AXDX) patients with Gram-positive bacteraemia were included. Median TTOT was 36.3 h (IQR, 16.9–56.7) in the pre-AXDX group and 20.4 h (IQR, 7.5–36.7) in the post-AXDX group (P = 0.01). Compared with pre-AXDX, median time to first antibiotic modification (29.1 versus 15.9 h; P = 0.002), time to first Gram-positive antibiotic modification (33.2 versus 17.2 h; P = 0.003) and median duration of unnecessary MRSA coverage (58.4 versus 29.7 h; P = 0.04) were reduced post-AXDX. A trend towards decreased acute kidney injury (24% versus 13%; P = 0.06) was observed in the post-AXDX group. Groups did not differ in other secondary outcomes.
Implementation of AXDX testing for patients with Gram-positive bacteraemia shortened the TTOT and reduced unnecessary antibiotic exposure due to faster antibiotic modifications.