Correlation of Strain Classification with IR Biotyper and Molecular Epidemiological Method of Pseudomonas aeruginosa.

Introduction: From 2018, IR Biotyper (IRBT; Bruker Daltonik GmbH, Germany) based on the Fourier transform infrared spectrophotometer has begun to be introduced as a new strain classification method in the field of clinical microbiological examination. We compared it with molecular epidemiology method to evaluate the usefulness of strain classification by IRBT.

Method: Homology of strain classification with molecular epidemiology method (Multilocus Sequencing Typing; MLST and PCR-based ORF Typing; POT) for 48 strains of Pseudomonas aeruginosa with different detection times from multiple institutions to evaluate the accuracy of IRBT was compared.

Results: IRBT used "KBM" SCD agar medium for preculture and was classified into 12 types when classified by Cut-off value 0.181, 8 types by MLST, and 13 types by POT. In the Adjusted Wallace between IRBT and molecular epidemiology method, MLST was 0.458 (95% CI; 0.295 to 0.620) and POT was 0.330 (95% CI; 0.135 to 0.525), indicating a discrepancy in strain classification.

Conclusion: No correlation was found between IRBT and the classification results by the molecular epidemiology method. In the molecular epidemiology method, strains are classified by matching only specific gene regions, but IRBT irradiates a sample with an infrared laser and classifies the strains according to the difference in absorption spectrum according to the molecular structure, so the measurement principle is different. When classifying strains by IRBT, it is desirable to grasp the clinical information of the detected strains and to target multiple strains isolated at the same facility at the same time.