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

• Published in: APMIS : acta pathologica, microbiologica et immunologica Scandinavica microbiologica et immunologica Scandinavica, 2014-09, Vol.122 (9), p.790-795
• Main Authors: March Rosselló, Gabriel A., Gutiérrez Rodríguez, María P., de Lejarazu Leonardo, Raúl Ortiz, Orduña Domingo, Antonio, Bratos Pérez, Miguel A.
• Format: Article
• Language: English
• Subjects: Bacterial Load; Bacterial Typing Techniques - methods; Desorption; direct identification; Gram-Negative Bacterial Infections - diagnosis; Gram-Negative Bacterial Infections - urine; Gram-Positive Bacterial Infections - diagnosis; Gram-Positive Bacterial Infections - urine; Humans; Ions; Lasers; MALDI-TOF; Mass spectrometry; Sepsis - diagnosis; Sepsis - microbiology; Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization - methods; urine
• ISSN: 0903-4641; 1600-0463
• DOI: 10.1111/apm.12208

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.