Quantamatrix Multiplexed Assay Platform system for direct detection of bacteria and antibiotic resistance determinants in positive blood culture bottles.

Objectives: Rapid and accurate identification of the causative pathogens of bloodstream infections (BSIs) is crucial for initiating appropriate antimicrobial therapy, which decreases the related morbidity and mortality rates. The aim of this study was to evaluate the usefulness of a newly developed multiplexed, bead-based bioassay system, the Quantamatrix Multiplexed Assay Platform (QMAP) system, obtained directly from blood culture bottles, to simultaneously detect the presence of bacteria and identify the genes for antibiotic resistance.

Methods: The QMAP system was used to evaluate 619 blood culture bottles from patients with BSIs and to compare the results of conventional culture methods.

Results: Using conventional bacterial cultures as the reference standard, the sensitivity, specificity, positive predictive value, and negative predictive value of the QMAP system for detection of bacterial pathogens in positive blood culture (PBC) samples were 99.8% (n=592, 95% CI 0.9852-1.000, p <0.001), 100% (95% CI 0.983-1.000, p <0.001), 100% (95% CI 0.9922-1.000, p <0.001), and 99.5% (95% CI 0.9695-1.000, p <0.001), respectively. In addition, sensitivity and specificity of the QMAP system for identification of the genes for antibiotic resistance were 99.4% (n=158, 95% CI 0.9617-0.9999, p <0.009) and 99.6% (95% CI 0.9763-0.9999, p <0.0001), respectively.

Conclusions: Obtaining results using the QMAP system takes about 3 hr, while culture methods can take 48-72 hr. Therefore, analysis using the QMAP system is rapid and reliable for characterizing causative pathogens in BSIs.