Species identification of lactose non-fermenting isolates from ventilator-associated pneumonia using VITEK 2 and matrix-assisted laser desorption ionization time-of-flight mass spectrometry: A comparative study with next-generation sequencing

Bacterial identification to species level is essential for appropriate and effective patient care, particularly in critical care units in patients with severe infections. In many microbiology laboratories where automation is available, the VITEK 2 system is widely utilized for the identification and antimicrobial susceptibility testing (AST) of clinical isolates. To assess the accuracy of bacterial identification, this study was undertaken to evaluate the concordance and percentage agreement, between the VITEK 2 system and matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF-MS)-based biomarker identification, with next-generation sequencing (NGS) serving as a gold standard. A total of 97 multidrug-resistant isolates were recovered from blood and respiratory specimens in patients on ventilator. The initial identification of these isolates was performed using VITEK 2 followed by identification by MALDI-TOF-MS and NGS. Our study revealed a high degree of concordance between the identification methods, with a 94.8% agreement rate between VITEK 2 and NGS, and a 92.7% agreement rate between MALDI-TOF-MS and NGS at the genus level. The study suggests that the VITEK 2 system is a viable and sufficient option for bacterial identification and susceptibility testing for appropriate antibacterial treatment in intensive care units wherever VITEK 2 is used as the primary ID and AST system.