Introduction

Rapid identification of microorganisms in clinical laboratory is important for patients’ management. Bacterial identification by conventional methods takes about 48hours after the receipt of specimens. However, matrix assisted laser desorption/ionization-time of flight (MALDI-TOF) is a relatively newly developed technique for rapid identification of microorganisms with high accuracy and low operating costs. We evaluated two different MALDI-TOF equipments with different platforms for identification of microorganisms in clinical specimens.        

Materials and methods

For evaluation of accuracy, 143 and 193 clinical specimens were tested with Vitek MS and Bruker biotyper respectively and the results were compared with the ones obtained by Vitek II. And for evaluation of precision, 16 and 20 American Type Culture Collection (ATCC) standard microorganisms were repeatedly tested daily for 20 days with Vitek MS and Bruker biotyper respectively.

Results

The concordance rate of Vitek MS was 91% with 130 concordant results and 13 discordant. Among the discordant results, gram negative was highest with 13% (11/84), one in gram positive (5%, 1/21) and yeast (3%, 1/38) respectively. Precision was 98% with 315 good identification, 1 low discrimination and 4 no identification. The concordance rate was 91% in Bruker biotyper with 176 concordant and 17 discordant results. Among discordant results, yeast was highest with 20% (2/10), gram negative 11% (11/97) and gram positive 5% (4/85). The precision was 98% with 432 good identification, 8 probable genus identification and 1 not reliable identification.

Conclusions

MALDI-TOF is accurate and precise tool for identification of microorganisms with reduced turnaround time and operating cost compared to conventional methods.