Evaluation of FASTinov Ultrarapid Flow Cytometry Antimicrobial Susceptibility Testing Directly from Positive Blood Cultures

Autores da FMUP

• Acácio Agostinho Gonçalves Rodrigues

  Autor

• Cidália Irene Azevedo Pina Vaz

  Autor

Participantes de fora da FMUP

• Silva-Dias, A
• Pérez-Viso, B
• Martins-Oliveira, I
• Gomes, R
• Cantón, R

Unidades de investigação

• Laboratório Associado RISE- Rede de Investigação em Saúde

  

  Investigador

  Fernando Carlos De Landér Schmitt

• Patologia

• RISE-Health

  

  Investigador

  Fernando Carlos De Landér Schmitt

Abstract

The FASTinov flow cytometry kit, an ultrarapid antimicrobial susceptibility test, was directly evaluated on positive blood cultures (BC) at two sites: (i) FASTinov, S.A., in Porto, Portugal, using BC spiked with well-characterized bacteria, and (ii) Ramon y Cajal University Hospital in Madrid, Spain, using positive BC from patients. Two kits were evaluated, FASTgramneg (Enterobacterales, Pseudomonas, Acinetobacter) and FASTgrampos (Staphylococcus, Enterococcus). Dedicated software for cytometric data analysis and interpretative reporting, including both CLSI and EUCAST criteria, was used. The FASTgramneg kit also provides information about the presence of resistant mechanisms, including extended-spectrum beta-lactamases (ESBLs) and carbapenemases. After 1 h of incubation at 37 degrees C, bacteria were analyzed using a CytoFLEX cytometer (Beckman, CA). Disk diffusion was performed as the reference susceptibility method. Overall, 447 positive BC were included, 100 from hospitalized patients. Categorical agreement values for the FASTgramneg panel were 96.8% based on EUCAST criteria and 96.4% based on CLSI criteria. For the FASTgrampos panel, categorical agreement was 98.6% when using both criteria. When EUCAST criteria were used, the percentages of errors for the FASTgramneg panel were 2.1% minor errors (mE), 1.3% major errors (ME), and 0.6% very major errors (VME). When CLSI criteria were used, 2.9% mE, 0.9% ME, and 0.4% VME were found. VME were mainly observed with amoxicillin-clavulanate, cefotaxime, ceftazidime, and gentamicin. The FASTgrampos panel showed 0.3% mE, 1.4% ME, and 0.4% VME when EUCAST criteria were used (VME with respect to gentamicin and Staphylococcus) and 0.4% mE, 1.4% ME, and no VME when CLSI criteria were used. The FASTinov flow cytometry kits represent a rapid alternative for direct antimicrobial susceptibility testing from positive BC, showing time to results of <2 h, and can be used to personalize antibiotic and stewardship practices.

Keywords

• antimicrobial resistance; antimicrobial susceptibility testing; detection of antimicrobial mechanisms of resistance; flow cytometry; Gram-negative bacteria; Gram-positive bacteria