New procedure for rapid identification of microorganisms causing urinary tract infection from urine samples by mass spectrometry (MALDI-TOF).

INTRODUCTION

Matrix assisted laser desorption/ionization-time of flight (MALDI-TOF) mass spectrometry is widely established as a technique in clinical microbiology laboratories for the identification of microorganisms. Using this technique, it is also possible to obtain the identification of microorganisms from untreated urine samples.

METHODS

In this study, a differential centrifugation protocol and a criterion for validation of the results in order to achieve microbial identification from untreated urine samples are proposed. Additionally, the sensitivity of the analytical procedure in monobacterial urine samples has been evaluated.

RESULTS

A 90% sensitivity (confidence interval of 81.96%-94.84%) was obtained in urine samples with bacterial counts of ≥1×10(5)CFU/ml, and it was possible to improve the percentages of direct identifications from urine samples with bacterial counts of <1×10(5)CFU/ml.

CONCLUSION

It is concluded that the MALDI-TOF system is both fast and reliable in the identification of individual microorganisms from untreated urine samples with counts of ≥1×10(5)CFU/ml.