A multisite validation of a two hours antibiotic susceptibility flow cytometry assay directly from positive blood cultures

• DOI: 10.1186/s12866-024-03341-1
• Publication Date: 2024-05-28T03:54:34Z
• Authors: C. Pina-Vaz; A. Silva-Dias; I. Martins-Oliveira; R. Gomes; B. Perez-Viso; S. Cruz; A. G. Rodrigues; A. Sarmento; R. Cantón
• Keywords: Broth microdilution; Clinical Microbiology

Abstract Background Rapid antimicrobial susceptibility testing (AST) is urgently needed to provide safer treatment counteract resistance. This critical in septic patients, because resistance increases empiric therapy uncertainty and the risk of a poor outcome. We validate novel 2h flow cytometry AST assay directly from positive blood cultures (PBC) by using room temperature stable FASTgramneg FASTgrampos kits (FASTinov® Porto, Portugal) three sites: FASTinov (site-1), Hospital Ramon y Cajal, Madrid, Spain (site-2) Centro Hospitalar S. João, Portugal (site-3). A total 670 PBC were included: 333 spiked (site-1) 337 clinical (151 site-2 186 site-3): 367 gram-negative 303 gram-positive. Manufacturer instructions followed for sample preparation, panel inoculation, incubation (1h/37ºC) analysis CytoFlex (Site-1 -2) or DxFlex (site-3) both instruments Beckman-Coulter, USA. Results proprietary software (bioFAST) was used immediately generate report less than 2 h. In parallel, samples processed according reference methods (disk diffusion and/or microdilution) interpreted with EUCAST CLSI criteria. Additionally, ten all sites inter-laboratory reproducibility. Sensitivity specificity >95% antimicrobials. Reproducibility 96.8%/95.0% 95.1%/95.1% regarding EUCAST/CLSI criteria, respectively. Conclusion FASTinov® consistently ultra-rapid high accuracy reproducibility on Gram-negative Gram-positive bacteria. technology creates new paradigm bacterial infection management holds potential significantly impact patient outcomes stewardship.