Concordance Between Multiplex-PCR Resistance-Gene Detection and MIC-Based Susceptibility in Gram-Negative Clinical Isolates from a Romanian Tertiary Hospital

Background/Objectives: Rapid molecular detection of antimicrobial resistance determinants has the potential to optimize antimicrobial therapy before conventional antimicrobial susceptibility testing becomes available. However, the clinical utility of these assays depends on the concordance between detected resistance genes and phenotypic susceptibility. This study aimed to evaluate the genotype-phenotype concordance of carbapenemase and β-lactamase genes detected by the Unyvero multiplex-PCR platform with minimum inhibitory concentration (MIC)-based susceptibility profiles obtained using the phenotypic AST comparator method in Gram-negative clinical isolates.

Methods

A total of 117 non-duplicate Gram-negative clinical isolates recovered from hospitalized patients at a Romanian tertiary-care hospital were analyzed. Resistance determinants, including blaKPC, blaOXA-48, blaOXA-23, blaCTX-M, blaTEM, together with aminoglycoside, fluoroquinolone, and sulfonamide resistance markers, were identified using the Unyvero multiplex-PCR system. Phenotypic antimicrobial susceptibility testing was performed using the VITEK®2 automated system according to EUCAST criteria. Genotype-phenotype concordance was evaluated using sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and Cohen's κ coefficient.