Comparison of Matrix-Assisted Laser Desorption Ionization Time of Flight Mass Spectrometry with VITEK2 Gram positive system for identification of beta hemolytic Streptococci

Abstract

Background: Matrix–assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS) is known as a successful tool for bacterial identification and suitable for clinical diagnostics. The aim of our study was to evaluate diagnostic accuracy of MALDI-TOF MS system and VITEK2 Gram Positive Identification (GP ID) system for the identification of Beta Hemolytic Streptococci (BHS).

Materials and Methods: A total 148 BHS which were isolated from various clinical specimens were included in the study. Isolates were identified by Bruker Biotyper 3.4 and VITEK2 GP ID coupled to the agglutination test. Identification results for Bruker Biotyper 3.4 and VITEK2 GP ID systems were classified in three different categories as follows: correct identification, low level of discrimination, no identification/misidentification. Identification results of BHS were evaluated according to these categories.

Results: BHS isolates were defined as Streptococcus pyogenes (n: 69), Streptococcus agalactiae (n: 59), Streptococcus dysgalactiae serogroup C (n: 5), and Streptococcus dysgalactiae serogroup G (n: 15) according to latex agglutination assay. MALDI-TOF MS analysis of 148 BHS isolates yielded correct identification for 89.9% of S. pyogenes, 64.4% of S. agalactiae, and 95.0% S. dysagalactiae serogroup C and G; while VITEK2 GP ID gave correct identification for 62.3% of S. pyogenes, 67.8% of S. agalactiae, and 65.0% of S. dysagalactiae serogroup C and G.

Conclusions: MALDI-TOF MS-based identification provides faster and more accurate identification of beta-hemolytic streptococcal species than VITEK2 GP ID system.

Keywords

• MALDI-TOF,VITEK,Beta Hemolytic Streptococci,S. pyogenes,S. agalactiae,S. dysagalactiae

References

1. 1. Facklam R. What happened to the streptococci: overview of taxonomic and nomenclature changes. Clin Microbiol Rev. 2002;15 (4): 13–30.
2. 2. Spellerberg B, Brandt C. Streptococci. In: Murray PR, Baron EJ, Jorgensen J, Pfaller M, Landry Ml, editors. Manual of clinical microbiology, 9th edn. Washington, D.C: ASM press; 2007 pp 412–30.
3. 3. Whiley R, Hardie JM. The streptococci. In: Vos P, Garrity G, Jones D, Krieg NR, Ludwig W, Rainey FA, Schleifer KH, Whitman W, editors. Bergeys manual of systematic bacteriology. New York: Springer; 2009 pp 689–90.
4. 4. Brandt C, Haase G. Characterization of blood culture isolates of Streptococcus dysgalactiae subsp. equisimilis possessing lancefield’s group aantigen. J Clin Microbiol. 1999; 37(12): 4194–7.
5. 5. Nomura F. Proteome-based bacterial identification using matrix-assisted laser desorption ionization–time of flight mass spectrometry (MALDI-TOF MS): A revolutionary shift in clinical diagnostic microbiology. Biochim Biophys Acta. 2015; 1854(6): 528-537.
6. 6. Fan WT, Qin TT, Bi RR, Kang HQ, Ma P, Gu B. Performance of the matrix-assisted laser desorption ionization time-of-flight mass spectrometry system for rapid identification of streptococci: a review. Eur J Clin Microbiol Infect Dis 2017; 36(6):1005-1012.
7. 7. Jensen CS, Dam-Nielsen C, Arpi M. Matrix-assisted laser desorption/ionization-time of flight mass spectrometry identification of large colony beta-hemolytic streptococci containing Lancefield groups A, C, and G. Infect Dis (Lond) 2015; 47(8): 575-579.
8. 8. Crowley E, Bird P, Fisher K, Goetz K., Boyle M, et al. Evaluation of the VITEK 2 gram positive (GP) microbial identification test card: collaborative study. Journal of AOAC International. 2012; 95(5): 1425-1432.

9. 9. Vitek 2 Systems, GP Product Information, 069042-6EN1, 4:1-24.
10. 10. i Y, Gu B, Liu G, Xia W, Fan K, Mei Y, et al. MALDI-TOF MS versus VITEK 2 ANC card for identification of anaerobic bacteria. J Thorac Dis. 2014; 6(5): 517-23.
11. 11. Bizzini A, Durussel C, Bille J, Greub G, Prod’hom G. Performance of matrix-assisted laser desorption ionization-time of flight mass spectrometry for identification of bacterial strains routinely isolated in a clinical microbiology laboratory. J Clin Microbiol. 2010;48(5): 1549–54.
12. 12. Funke G, Funke-Kissling P. Performance of the new VITEK 2 GP card for identification of medically relevant gram-positive cocci in a routine clinical laboratory. J Clin Microbiol. 2005; 43(1): 84-88.
13. 13. Neville SA, Lecordier A, Ziochos H, Chater MJ, Gosbell IB, et al. Utility of matrix-assisted laser desorption ionization-time of flight mass spectrometry following introduction for routine laboratory bacterial identification. J Clin Microbiol. 2011; 49(8): 2980–4.
14. 14. Cherkaoui A, Emonet S, Fernandez J, Schorderet D, Schrenzel J. Evaluation of matrix-assisted laser desorption ionization-time of flight mass spectrometry for rapid identification of beta-hemolytic streptococci. J Clin Microbiol 2011; 49(8): 3004–5.
15. 15. Van Veen SQ, Claas ECJ, Kuijper EJ. High-throughput identification of bacteria and yeast by matrix-assisted laser desorption ionization-time of flight mass spectrometry in conventional medical microbiology laboratories. J Clin Microbiol 2010; 48(3): 900–7.
16. 16. Alatoom AA, Cunningham SA, Ihde SM, Mandrekar J, Patel R. Comparison of direct colony method versus extraction method for identification of gram-positive cocci by use of Bruker Biotyper matrix-assisted laser desorption ionization-time of flight mass spectrometry. J Clin Microbiol. 2011; 49(8): 2868–73.
17. 17. Zhou C, Tao L, Hu B, Ma J, Ye X, Huang S, et al. Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry for the identification of beta-hemolytic streptococc.i J Thorac Dis. 2015; 7(4):591.
18. 18. Lamm CG, Ferguson AC, Lehenbauer TW, Love BC. Streptococcal infection in dogs: a retrospective study of 393 cases. Vet pathol 2010; 47(3): 387–95.
19. 19. Whatmore AM, Engler KH, Gudmundsdottir G, Efstratiou A. Identification of isolates of Streptococcus canis infecting humans. J Clin Microbiol 2001; 39(11): 4196.