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. 2017 Dec 29;12(12):e0190038.
doi: 10.1371/journal.pone.0190038. eCollection 2017.

Validation of a novel automatic deposition of bacteria and yeasts on MALDI target for MALDI-TOF MS-based identification using MALDI Colonyst robot

Katerina Chudejova  1 , Michal Bohac  2 , Anna Skalova  1   3 , Veronika Rotova  1 , Costas C Papagiannitsis  1 , Jana Hanzlickova  3 , Tamara Bergerova  1   3 , Jaroslav Hrabák  1   3
Affiliations

Validation of a novel automatic deposition of bacteria and yeasts on MALDI target for MALDI-TOF MS-based identification using MALDI Colonyst robot

Katerina Chudejova et al. PLoS One. .

Abstract

Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) -based identification of bacteria and fungi significantly changed the diagnostic process in clinical microbiology. We describe here a novel technique for bacterial and yeast deposition on MALDI target using an automated workflow resulting in an increase of the microbes' score of MALDI identification. We also provide a comparison of four different sample preparation methods. In the first step of the study, 100 Gram-negative bacteria, 100 Gram-positive bacteria, 20 anaerobic bacteria and 20 yeasts were spotted on the MALDI target using manual deposition, semi-extraction, wet deposition onto 70% formic acid and by automatic deposition using MALDI Colonyst. The lowest scores were obtained by manual toothpick spotting which significantly differ from other methods. Identification score of semi-extraction, wet deposition and automatic wet deposition did not significantly differ using calculated relative standard deviation (RSD). Nevertheless, the best results with low error rate have been observed using MALDI Colonyst robot. The second step of validation included processing of 542 clinical isolates in routine microbiological laboratory by a toothpick direct spotting, on-plate formic acid extraction (for yeasts) and automatic deposition using MALDI Colonyst. Validation in routine laboratory process showed significantly higher identification scores obtained using automated process compared with standard manual deposition in all tested microbial groups (Gram-positive, Gram-negative, anaerobes, and yeasts). As shown by our data, automatic colony deposition on MALDI target results in an increase of MALDI-TOF MS identification scores and reproducibility.

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Conflict of interest statement

Competing Interests: The authors declare the following interests: Patent applications for automatic depositions using MALDI-TOF MS target have been submitted (Industrial Property Office of the Czech Republic, Nr. PV2015-847). The study was partially supported by the company BioVendor – Laboratorní medicína, a.s. (Brno, Czech Republic) as a contractual research performed in Biomedical Center of Faculty of Medicine in Plzen. Author Michal Bohac is affiliated with Bruker s.r.o., Prazakova 60, Brno, Czech Republic. This does not alter the authors’ adherence to all PLOS ONE policies on sharing data and materials.

Figures

Fig 1
Fig 1. Comparison of different deposition methods with plotted RSD.
Statistically significant differences are indicated by asterisks.
See this image and copyright information in PMC

References

    1. Croxatto A, Prod’hom G, Faverjon F, Rochais Y, Greub G. Laboratory automation in clinical bacteriology: what system to choose? Clinical Microbiology and Infection. 2016; 22: 217–235. doi: 10.1016/j.cmi.2015.09.030 - DOI - PubMed
    1. Ledeboer NA, Dallas SD. The Automated Clinical Microbiology Laboratory: Fact or Fantasy? Journal of Clinical Microbiology. 2014; 52: 3140–3146. doi: 10.1128/JCM.00686-14 - DOI - PMC - PubMed
    1. Buchan BW, Ledeboer NA. Emerging technologies for the clinical microbiology laboratory. Clinical Microbiology Reviews. 2014; 27: 783–822. doi: 10.1128/CMR.00003-14 - DOI - PMC - PubMed
    1. Lay JO. MALDI-TOF mass spectrometry of bacteria. Mass Spectrometry Reviews. 2001; 20: 172–194. doi: 10.1002/mas.10003 - DOI - PubMed
    1. Patel R. MALDI-TOF MS for the diagnosis of infectious diseases. Clinical Chemistry 2015; 61: 100–111. doi: 10.1373/clinchem.2014.221770 - DOI - PubMed

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