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 × 107 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 × 105 and 1 × 107 bacteria/ml requires preincubation to obtain the adequate amount of bacteria needed for analysis, and 91.7% sensitivity thus being achieved.