Clinical efficacy of matrix-assisted laser desorption/ionization time-of-flight mass spectrometry in patients with multidrug-resistant bacteremia: a single-center study in Korea

BACKGROUND/AIMS

Matrix-assisted laser desorption/ionization time-of-f light mass spectrometry (MALDI-TOF MS) is a new diagnostic tool for microorganism identification. The clinical usefulness of this approach has not been widely examined in Korea. This retrospective pre-post-intervention quasi-experimental study examined the effect of MALDI-TOF MS on patients with multidrug-resistant (MDR) bacteremia in the intensive care unit (ICU).

METHODS

All consecutive patients with MDR bacteremia in the ICU of a tertiary care hospital between March 2011 and February 2013 and between March 2014 and February 2016 were enrolled. MALDI-TOF MS was introduced between these periods. In the pre-intervention and intervention groups, microorganisms were identified by conventional means and by MALDI-TOF MS, respectively. The groups were compared in terms of time from venipuncture to microorganism identification and antimicrobial susceptibility test results.

RESULTS

In total, 187 patients (mean age, 61.0 years; 56.7% male) were enrolled. Of these, 97 and 90 were in the pre-intervention and intervention groups, respectively. The intervention group had a significantly shorter time from venipuncture to microorganism identification and antimicrobial susceptibility test results (82.5 ± 21.6 hours vs. 92.3 ± 40.4 hours, p = 0.038). The antibiotics were adjusted in 52 patients (26 each in the pre-intervention and intervention groups) based on these results. These groups did not differ in terms of time from venipuncture to antibiotic adjustment, and multivariate regression analysis showed that MALDI-TOF MS-based microorganism identification was not associated with 28-day mortality.

CONCLUSION

Our study showed that MALDI-TOF MS accelerated microorganism identification in patients with MDR bacteremia, but did not inf luence 28-day mortality.

[Performance of matrix assisted laser desorption ionization time of flight biotyper system in clinical bacteria identification]

Objective: To evaluate the performance of MALDI Biotyper system in identification of clinically isolated pathogens so as to provide a new rapid identification method. Methods: Total 21 270 pathogens strains, isolated from the First Affiliated Hospital of Fujian Medical Universityduring Nov. 2015 to Dec. 2016, were identified by VITEK-Ⅱ, API and MALDI Biotyper system, respectively.The isolated strains were confirmed by DNA sequencing. Results: The identification of common bacteria with MALDI Biotyper and phenotypic system is highly consistent (>95% and >90%). Among 43 strains of anaerobic bacteria, MALDI Biotyper could identify 90.7% bacteria to species level and 97.7% bacteria to genus level with the statistical significance(χ(2)=6.76, P<0.01), while phenotypic system only identified 65.1% bacteria to species and 69.8% bacteria to genus. Also, no statistical significance was shown for Trichosporon and Candida(P>0.05). MALDI Biotyper could identify 76% filamentous fungi and all of Actinomycetes, Nocardia, Mycobacterium and Legionella to genus level. Conclusions: MALDI Biotyper is an easy-performed, sensitive method for the identification of clinically isolated pathogens. Additionally, the pretreatment and reference database has the effect on identification.

Application of Matrix-Assisted Laser Desorption/Ionization Time-of-Flight Imaging Mass Spectrometry (MALDI-TOF IMS) for Premalignant Gastrointestinal Lesions

Imaging mass spectrometry (IMS) is currently receiving large attention from the mass spectrometric community, although its use is not yet well known in the clinic. As matrix-assisted laser desorption/ionization time-of-flight (MALDI)-IMS can show the biomolecular changes in cells as well as tissues, it can be an ideal tool for biomedical diagnostics as well as the molecular diagnosis of clinical specimens, especially aimed at the prompt detection of premalignant lesions much earlier before overt mass formation, or for obtaining histologic clues from endoscopic biopsy. Besides its use for pathologic diagnosis, MALDI-IMS is also a powerful tool for the detection and localization of drugs, proteins, and lipids in tissue. Measurement of parameters that define and control the implications, challenges, and opportunities associated with the application of IMS to biomedical tissue studies might be feasible through a deep understanding of mass spectrometry. In this focused review series, new insights into the molecular processes relevant to IMS as well as other field applications are introduced.