A Proof-of-Concept of a 2-Hours Direct Antimicrobial Susceptibility Test from Inoculated Urine Samples

Area of Science:

• Clinical microbiology
• Infectious diseases
• Medical diagnostics

Background:

• Urinary tract infections (UTIs) are common, with *Escherichia coli* as a primary cause.
• Conventional antimicrobial susceptibility testing (AST) methods take 48 hours, leading to empirical antibiotic use and antimicrobial resistance (AMR).

Purpose of the Study:

• To evaluate the performance of the rapid phenotypic FASTinov® method for AST directly from urine samples.
• To assess the accuracy and speed of FASTinov® compared to conventional AST methods for UTI pathogens.

Main Methods:

• Analysis of 154 inoculated urine samples using FASTinov® FASTgramneg and FASTgrampos panels with flow cytometry.
• Data analysis using bioFAST® software (version 3.0) aligned with EUCAST guidelines.
• Evaluation of resistance mechanisms (ESBLs, AmpC, carbapenemases) and vancomycin MIC for *Staphylococcus aureus*.

Main Results:

• High overall agreement with conventional AST: 97.5% for Gram-negative and 95.0% for Gram-positive bacteria.
• Accurate identification of all resistance mechanisms without false positives.
• Essential agreement for vancomycin MIC was 95.2% with a BIAS of +14.3%; reproducibility was 99.5% (FASTgramneg) and 95.0% (FASTgrampos).

Conclusions:

• The FASTinov® kit offers a rapid, accurate alternative to conventional AST for UTIs, reducing turnaround time from 48 hours to 2 hours.
• This technology supports improved UTI management and promotes effective antimicrobial stewardship by enabling timely, targeted therapy.