Background: Rapid blood culture diagnostics are costly and of unclearbenefit for patients with Gram-negative bacilli (GNB) bloodstream infections (BSIs). We conducted a multicenter, prospective, randomized controlled trial comparing outcomes of patients with GNB BSI who had blood culture testing with standard of care (SOC) culture and antimicrobial susceptibility testing (AST) versus rapid organism identification (ID) and phenotypic AST using the Accelerate Pheno™ System (RAPID).
Methods: Patients with positive blood cultures with Gram stains showing GNB were randomized to SOC testing with antimicrobial stewardship review (AS) or RAPID with AS, at two medical centers between 10/2017-10/2018. The primary outcome was time to first antibiotic modification within 72 hours of randomization.
Results: Of 500 randomized subjects, 448 were included (226 SOC, 222 RAPID). Mean (S.D.) hours to results was faster for RAPID than SOC for organism ID [2.7 (1.2) vs 11.7 (10.5), p < 0.001] and AST [13.5 (56) vs. 44.9 (12.1), p<0.001]. Median (IQR) hours to first antibiotic modification was faster in the RAPID vs. SOC arm for overall antibiotics [8.6 (2.6, 27.6) vs. 14.9 (3.3, 41.1), difference 6.3, p=0.02] and Gram-negative antibiotics [17.3 (4.9, 72) vs. 42.1 (10.1, 72), difference 24.8, p<0.001]. Median (IQR) hours to antibiotic escalation was faster in the RAPID vs. SOC arm for antimicrobial-resistant BSIs [18.4 (5.8, 72) vs. 61.7 (30.4, 72), difference 43.3, p=0.01]. There were no statistically significant differences between the arms in patient outcomes including mortality and length of stay.
Conclusion: Rapid organism ID and phenotypic AST led to faster changes in antibiotic therapy for Gram-negative BSIs. (Funded by the U.S. NIH UM1AI104681; ClinicalTrials.gov number, NCT03218397.).
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