Vitek 2 ast gp 67 cards

Cultures were performed according to the working protocol of the Bacteriology Laboratory of SCJUPBT. All isolates were first identified using the VITEK^® 2 GN, VITEK^® 2 GP ID cards (BioMérieux, Marcy l’Etoile, France). Antimicrobial susceptibility tests (AST) were performed using the VITEK 2 GN AST-N222 and VITEK 2 AST GP 67 cards (BioMérieux, Marcy l’Etoile, France) by determination of the minimum inhibitory concentration (MIC) and classification into resistance phenotypes, according to the Clinical Laboratory and Standards Institute (CLSI) 2020/2021 criteria. The reference strains used were: Escherichia coli ATCC 25922 and Klebsiella pneumoniae ATCC 1705, Pseudomonas aeruginosa ATCC 27853, Staphylococcus aureus ATCC 25923. Clostridioides difficile enterocolitis was diagnosed by determining the A and/or B toxin from the spontaneously emitted feces by using the LIAISON^® Analyzer through an automatic immunoassay testing.

Following identification by matrix-assisted laser desorption ionization-time of flight mass spectrometry, S. aureus isolates were subjected to antimicrobial susceptibility testing to determine their antibiotic resistance phenotypes. Each bacterial colony was resuspended in 0.45% sodium chloride (bioMérieux) by using sterile swabs to prepare 0.5-McFarland suspensions, in accordance with the manufacturer’s recommendations. Subsequently, 280 µL of bacterial suspension was diluted in 3 mL of 0.45% sodium chloride and transferred into Vitek-2 AST-GP67 cards, which were then loaded into the Vitek-2 Compact system (bioMérieux) for automatic incubation and reporting. Raw minimum inhibitory concentrations (μg/mL) were converted to sensitive, intermediate, and resistant classifications, in accordance with the 2018 guidelines from the Clinical and Laboratory Standard Institute.¹⁴ S. aureus ATCC 25923 was used as a quality control for antimicrobial susceptibility testing.