Performances and Reliability of Bruker Microflex LT and VITEK MS MALDI-TOF Mass Spectrometry Systems for the Identification of Clinical Microorganisms

Abstract

In clinical microbiology laboratories, routine microbial identification is mostly performed using culture based methodologies requiring 24 to 72 hours from culturing to identification. Matrix assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) technology has been established as a cost effective, reliable, and faster alternative identification platform. In this study, we evaluated the reliability of the two available MALDI-TOF MS systems for their routine clinical level identification accuracy and efficiency in a clinical microbiology laboratory setting. A total of 1,341 routine phenotypically identified clinical bacterial and fungal isolates were selected and simultaneously analyzed using VITEK MS (bioMérieux, France) and Microflex LT (Bruker Diagnostics, Germany) MALDI-TOF MS systems. For any isolate that could not be identified with either of the systems and for any discordant result, 16S rDNA gene or ITS1/ITS2 sequencing was used. VITEK MS and Microflex LT correctly identified 1,303 (97.17%) and 1,298 (96.79%) isolates to the species level, respectively. In 114 (8.50%) isolates initial phenotypic identification was inaccurate. Both systems showed a similar identification efficiency and workflow robustness, and they were twice as more accurate compared to routine phenotypic identification in our sample pool. MALDITOF systems with their accuracy and robustness offer a good identification platform for routine clinical microbiology laboratories.

Diagnostic microbiology in veterinary dermatology: present and future

“…One technology that has gained increasing attention in veterinary microbiology is MALDI‐TOF (matrix‐assisted laser desorption/ionization‐time of flight) mass spectrometry (MS) (Figure ). This technique identifies any culturable bacteria within minutes and has low running costs . For most fungi a somewhat more complex sample preparation is necessary, but even dermatophytes can be identified with this method within 2 h. Again, identification depends on database entries, but the ability to discriminate between different bacteria is generally very good for most species.…”

“…This technique identifies any culturable bacteria within minutes and has low running costs. 12,13 For most fungi a somewhat more complex sample preparation is necessary, but even dermatophytes can be identified with this method within 2 h. Again, identification depends on database entries, but the ability to discriminate between different bacteria is generally very good for most species. In general, the available databases are much broader than any of the former biochemistry based databases, but still some veterinary specific entries are lacking.…”

La espectrometría de masas MALDI-TOF en el laboratorio de microbiología clínica

“…Las puntuaciones de registro que van desde 1,700 a 1,999 representan una probable identificación de género, que requiere pruebas adicionales para una identificación positiva a nivel de la especie del microorganismo. Las puntuaciones de registro que van desde 1,699 a 0,000 no se consideran una identificación fiable 3,17 .…”

“…Esto también fue reportado por Bilecen y colaboradores 17 , en un estudio en 1341 aislamientos clínicos que demostró que MALDI-TOF MS arrojó resultados de identificación en un periodo entre 5 a 30 minutos, superando en oportunidad del resultado a los métodos bioquímicos convencionales, que tardan entre 6-18 horas.…”

“…El rango de probabilidades para una identificación correcta es 60-99% y valores cercanos a 99,9% indican una aproximación más exacta. Cuando el porcentaje de probabilidad es menor al 60% el microorganismo se considera como no identificado 17 .…”