Procedure for microbial identification based on Matrix-Assisted Laser Desorption/Ionization-Time of Flight Mass Spectrometry from screening-positive urine samples

Matrix-Assisted Laser Desorption/Ionization-Time of Flight Mass Spectrometry is a widely used proteomic technique in clinical microbiology laboratories, and enables microbial identification directly from clinical samples. This study seeks to establish a protocol for bacterial identification from monomicrobial urine samples that have tested positive in the screening with Sysmex UF-1000i (Sysmex Corporation, Kobe, Japan). Sysmex UF-1000i counts >= 1 x 10(7) bacteria/mL indicate a sufficient bacterial concentration to allow direct identification from urine, with 87.5% sensitivity. Microbial identification from urine with Sysmex UF-1000i counts between 1 x 10(5) and 1 x 10(7) bacteria/ml requires preincubation to obtain the adequate amount of bacteria needed for analysis, and 91.7% sensitivity thus being achieved.