Evaluation of IR BIOTYPER® as a new tool for Enterobacter cloacae complex typing and its potential in management of nosocomial infections.

BACKGROUND

Traditional typing methods, such as pulsed-field gel electrophoresis (PFGE), multi-locus sequence typing (MLST) and Whole genome sequencing (WGS) have limitations in terms of labor intensity, cost, and delayed results. This study evaluates Fourier transform infrared spectroscopy (FTIR), particularly IR Biotyper® system (IRBT), as an alternative typing method for E. cloacae complex.

METHODS

The research involves retrospective analysis of 72 carbapenem-resistant strains of E. cloacae complex, assessing the IR Biotyper's efficacy, discriminatory power, and concordance with PFGE and WGS. Clustering concordance was evaluated using Simpson's index of diversity (SID) and adjusted Rand index (ARI). Methodology was tested in a real-world outbreak investigation compared with WGS.

RESULTS

The results underscore the benefits of IRBT, which include rapid turnaround times under 3 h, cost-effectiveness, and operational simplicity. IR Biotyper® had greater discriminatory power (SID: 0.709) than PFGE (SID: 0.694) and nearly the same as WGS (SID: 0.704). The concordance of IRBT with the other two methods was assessed by the adjusted Rand index (ARI), showing values close to unity in both cases, indicating near-perfect agreement. Moreover, the methodology proves effective in real-world outbreak investigations, demonstrating its potential integration into routine clinical microbiology practices.

CONCLUSIONS

Our study proposes FTIR as a powerful tool for typing of E. cloacae complex, specifically IR Biotyper®, offering high discriminatory power and providing results in a shorter time, compared to conventional methods. However, there is urgent need for standardization of cutoff values, which is a fundamental challenge to address in order to facilitate its use and extrapolation of results between laboratories.