High-Throughput Identification of Bacteria and Yeast by Matrix-Assisted Laser Desorption Ionization-Time of Flight Mass Spectrometry in Conventional Medical Microbiology Laboratories

Abstract

Matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) is suitablefor high-throughput and rapid diagnostics at low costs and can be considered an alternative for conventional biochemical and molecular identification systems in a conventional microbiological laboratory. First, we evaluated MALDI-TOF MS using 327 clinical isolates previously cultured from patient materials and identified by conventional techniques (Vitek-II, API, and biochemical tests). Discrepancies were analyzed by molecular analysis of the 16S genes. Of 327 isolates, 95.1% were identified correctly to genus level, and 85.6% were identified to species level by MALDI-TOF MS. Second, we performed a prospective validation study, including 980 clinical isolates of bacteria and yeasts. Overall performance of MALDI-TOF MS was significantly better than conventional biochemical systems for correct species identification (92.2% and 83.1%, respectively) and produced fewer incorrect genus identifications (0.1% and 1.6%, respectively). Correct species identification by MALDI-TOF MS was observed in 97.7% of Enterobacteriaceae, 92% of nonfermentative Gram-negative bacteria, 94.3% of staphylococci, 84.8% of streptococci, 84% of a miscellaneous group (mainly Haemophilus, Actinobacillus, Cardiobacterium, Eikenella, and Kingella [HACEK]), and 85.2% of yeasts. MALDI-TOF MS had significantly better performance than conventional methods for species identification of staphylococci and genus identification of bacteria belonging to HACEK group. Misidentifications by MALDI-TOF MS were clearly associated with an absence of sufficient spectra from suitable reference strains in the MALDI-TOF MS database. We conclude that MALDI-TOF MS can be implemented easily for routine identification of bacteria (except for pneumococci and viridans streptococci) and yeasts in a medical microbiological laboratory.

An Evaluation Of Direct Identification Of Pathogens From Blood Cultures By Maldi-Tof Mass Spectrometry

“…With a special set of MALDI Sepsityper is possible to identify bacteria directly from the positive blood culture (17)(18)(19)(20)(21)(22)(23)(24)(25). Most reports describe the blood culture must be grown in automated BACTEC system vials (26,27).…”

Traumatic Wound Microbiome Workshop

“…As the database grows, the concordance with the gold standard identifications increases steadily. At this time, it is at 98 % for bacteria and yeast species [40][41][42][43][44]. Even the difficulties are now predictable; foreseeable, reliable difficulties can be circumvented.…”

Utilisation en routine du MALDI-TOF-MS pour l’identification des pathogènes en microbiologie médicale

“…La première stratégie impose d'avoir un très grand nombre de souches par espèce dans la banque de données à l'inverse de la seconde. fréquemment isolées varie de 87 % à 99 % (Tableau 1) [13][14][15][16][17][18]. Les entérobactéries ne posent pas de problème majeur avec une identification correcte de l'espèce dans 97 % à 99 % des échantillons selon les études.…”

“…dont les spectres ne sont pas présents dans toutes les bases de données [13,15]. Parmi les cocci à Gram positif, les streptocoques du groupe mitis sont particulièrement difficiles à identifier et à distinguer de Streptococcus pneumoniae [13][14][15]. Une autre application de cette technologie est l'identification des bactéries directement à partir des prélèvements, soit à partir de flacons d'hémocultures détectés comme positifs [19][20][21][22][23][24][25], soit à partir des urines [23].…”