Recently, while reviewing information a piece of literature caught the author’s attention. The Medical University of Graz, Austria, recently published an article in the Journal of Clinical Microbiology (IF=9.4) entitled “A head-to-head comparison of three MALDI-TOF mass spectrometry systems with 16S rRNA gene sequencing”. systems with 16S rRNA gene sequencing”.

The article evaluated the performance of three MALDI-TOF mass spectrometry systems: MALDI Biotyper (Bruker), EXS 2600 (Zybio), and Vitek MS (bioMérieux), of which Zybio is a Chinese manufacturer, while Bruker and bioMérieux are world-renowned brands in the field of microbial mass spectrometry.

Europe and the United States market initiative to assess the situation of Chinese products is not common, the domestic mass spectrometry database will be in foreign countries “not suit”, with the results of the curiosity to read the entire article.

In the article, the team from the Medical University of Graz mentioned that although MALDI-TOF MS is very important in diagnostics, there are very few instruments and databases to choose from in the European region, with only Bruker and bioMérieux, and that Zybio mass spectrometry is emerging as a new option in the market, and is being used in a number of teaching hospitals and large-scale clinical laboratories, and therefore evaluated the performance of three mass spectrometry systems. The performance of the three mass spectrometry systems was evaluated.

The team collected 365 strains of bacteria that are difficult to identify in daily clinical practice and conducted parallel tests using the three mass spectrometry systems. The effective detection rates of the MALDI Biotyper, EXS 2600, and Vitek MS were 98.6%, 94.4%, and 93.3%, respectively, with concordance with the sequencing results of 98.9%, 98.5%, and 99.7%, respectively. It was concluded that all three instruments could meet the requirements of clinical microbiological testing.

Experiments and methods

All strains were obtained from the Medical University of Graz and were tested by specialized personnel, the first time they were tested using the direct coating method and failed to be identified, the samples were re-collected once, and when the re-testing also failed, they were re-tested using the formic acid extraction method.

Table 1 Taxonomic distribution of strains
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Results

Due to the different design of the three systems for their respective databases, some of the strain identification results differed at the green level (higher confidence level) or yellow level (lower confidence level), and the results may show a single strain or multiple strains.

The final results showed that 91.0%, 85.7% and 81.7% of the results of the three systems, Biotyper, EXS 2600 and Vitek MS, respectively, were single strains; 92.1%, 87.4% and 86.8% of the results of the three systems were at the green level, respectively; and the percentage of the effective detection rate of the three systems was 98.6%, 94.4%, 93.3%. 93.3%.

Table 2 Effective rates of the results of the three MALDI-TOF mass spectrometry systems.
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In addition to single identification results, MALDI-TOF MS results were also considered correct when at least one species among multiple results was consistent with 16S rRNA gene sequencing results. The final results showed that the concordance between the three systems, Biotyper, EXS 2600, and Vitek MS, and the 16S rRNA gene sequencing results among the validated detections were 98.9%, 98.5%, and 99.7%, respectively.

Table 3 Agreement between 16S rRNA gene sequencing and MALDI-TOF mass spectrometry measurements
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Discussion.

The team pointed out that this is the first study to compare the three MALDI-TOF mass spectrometry systems in parallel, although the sample size is not large, the team deliberately paid attention to some difficult to identify bacteria, according to the results, the three MALDI-TOF mass spectrometry systems are proved to be a valuable identification tool for microbiology laboratories, in line with the requirements of clinical microbiological diagnosis, it seems that the domestic mass spectrometry has been well solved the problem of geographical differences in the identification of bacteria. It seems that domestic mass spectrometry has well solved the problem of geographical differences in strain identification.

Unfortunately, the strains included in this parallel comparison did not involve fungi, which are of great concern in clinical microbiology. We look forward to more scenarios of evaluating China’s advanced technology in the future, and we also expect that China’s technology will continue to shine in the international arena.

Medical University of Graz, Austria

Founded in 2004, the Medical University of Graz, Austria, is located in Graz, the capital of the Austrian state of Steiermark in the southeast of Austria, which is the second largest city in Austria. The university has established numerous research institutes, actively participates in major medical research programs, emphasizes both teaching and research, and has achieved world-class scientific research results. Its medical program, ranked between 100th and 150th in the world.