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Performance of MALDI Biotyper for Species Identification of Carbapenem-Resistant Enterobacteriaceae by Media Types and Incubation Time
J Lab Med Qual Assur 2018;40:155-160
Published online September 30, 2018
© 2018 Korean Association of External Quality Assessment Service.

Young Eun Cho, Byoung Hu Choi, Jeonghyun Chang, Heungsup Sung, and Mi-Na Kim

Department of Laboratory Medicine, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea
Correspondence to: Mi-Na Kim
Department of Laboratory Medicine, Asan Medical Center, University of Ulsan College of Medicine, 88 Olympic-ro 43-gil, Songpa-gu, Seoul 05505, Korea
Tel: +82-2-3010-4511
Fax: +82-2-478-0884
Received January 3, 2018; Revised July 10, 2018; Accepted August 2, 2018.
This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License ( which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.
Background: This study was conducted to evaluate the impact of the media type used for direct identification of colonies on the surveillance culture of carbapenem-resistant Enterobacteriaceae (CRE) by matrix assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS).
Methods: CRE surveillance culture isolates were subjected to species identification using the MALDI Biotyper (Bruker Daltonics, Germany) for 2 months starting in March 2017. Four types of media were evaluated: blood agar (BA), Mueller Hinton agar (MH), MacConkey agar (Mac), and MacConkey agar containing imipenem of 1 關g/mL (IMP-Mac). CRE-like colonies on IMP-Mac and their subculture colonies on the other media were tested after overnight incubation and extended incubation for one additional day. The percent identification and score value were analyzed for each media types and incubation time when the identification was correct at the genus level.
Results: A total of 117 isolates were identified as 84 Klebsiella pneumoniae , 12 Escherichia coli , 9 Enterobacter cloacae , 5 Klebsiella oxytoca , 4 Enterobacter aerogenes , and 2 Raoultella ornithinolytica . The successful identification rates (SIR) for BA and MH were 98.3% and 97.4% (P=0.9), respectively, while those for Mac and IMP-Mac were 82.1% (P竊0.001) and 70.9% (P竊0.001), respectively. After extended incubation, SIRs were decreased to 96.6%, 96.6% (P=1.0), 61.5% (P竊0.001), and 58.1% (P竊0.001) on BA, MH, Mac, and IMP-Mac, respectively. The average score values were significantly lower for Mac (2.017짹0.22) and IMP-Mac (1.978짹0.24) than for BA (2.213짹0.16) (P竊0.001).
Conclusions: The low performance of the MALDI Biotyper applied directly to the colonies grown on Mac or IMP-Mac indicates that subculture on BA or MH is preferable before identification by MALDI-TOF MS.
Keywords : Carbapenem-resistant Enterobacteriaceae, Surveillance, MALDI-TOF, Media type, Incubation time
  1. Lee HJ, Lee DG. Carbapenem-resistant Enterobacteriaceae:recent updates and treatment strategies. J Korean Med Assoc 2018;61:281-9.
  2. Jeong SH, Kim HS, Kim JS, Shin DH, Kim HS, Park MJ, et al. Prevalence and molecular characteristics of carbapenemaseproducing Enterobacteriaceae from five hospitals in Korea. Ann Lab Med 2016;36:529-35.
    Pubmed KoreaMed CrossRef
  3. Kim KR, Lee JY, Park HY, Kwak SH, Lim YJ, Hong MJ, et al. Clearance rate of carbapenemase-producing Enterobacteriaceae carriage among hospitalized patients. Infect Control Hosp Epidemiol 2015;36:1361-2.
    Pubmed CrossRef
  4. Yoon EJ, Yang JW, Kim JO, Lee H, Lee KJ, Jeong SH. Carbapenemase-producing Enterobacteriaceae in South Korea: a report from the National Laboratory Surveillance System. Future Microbiol 2018;13:771-83.
    Pubmed CrossRef
  5. Bizzini A, Greub G. Matrix-assisted laser desorption ionization time-of-flight mass spectrometry, a revolution in clinical microbial identification. Clin Microbiol Infect 2010;16:1614-9.
    Pubmed CrossRef
  6. Clark AE, Kaleta EJ, Arora A, Wolk DM. Matrix-assisted laser desorption ionization-time of flight mass spectrometry:a fundamental shift in the routine practice of clinical microbiology. Clin Microbiol Rev 2013;26:547-603.
    Pubmed KoreaMed CrossRef
  7. De Carolis E, Vella A, Vaccaro L, Torelli R, Spanu T, Fiori B, et al. Application of MALDI-TOF mass spectrometry in clinical diagnostic microbiology. J Infect Dev Ctries 2014;8:1081-8.
    Pubmed CrossRef
  8. Seng P, Drancourt M, Gouriet F, La Scola B, Fournier PE, Rolain JM, et al. Ongoing revolution in bacteriology:routine identification of bacteria by matrix-assisted laser desorption ionization time-of-flight mass spectrometry. Clin Infect Dis 2009;49:543-51.
    Pubmed CrossRef
  9. Fenselau C, Demirev PA. Characterization of intact microorganisms by MALDI mass spectrometry. Mass Spectrom Rev 2001;20:157-71.
    Pubmed CrossRef
  10. Anderson NW, Buchan BW, Riebe KM, Parsons LN, Gnacinski S, Ledeboer NA. Effects of solid-medium type on routine identification of bacterial isolates by use of matrix-assisted laser desorption ionization-time of flight mass spectrometry. J Clin Microbiol 2012;50:1008-13.
    Pubmed KoreaMed CrossRef
  11. Reich M, Bosshard P, Stark M, Beyser K, Borgmann S. Species identification of bacteria and fungi from solid and liquid culture media by MALDI-TOF mass spectrometry. J Bacteriol Parasitol 2013;S5:002.
  12. Buskirk AD, Hettick JM, Chipinda I, Law BF, Siegel PD, Slaven JE, et al. Fungal pigments inhibit the matrixassisted laser desorption/ionization time-of-flight mass spectrometry analysis of darkly pigmented fungi. Anal Biochem 2011;411:122-8.
    Pubmed CrossRef
  13. Idelevich EA, Schule I, Grunastel B, Wullenweber J, Peters G, Becker K. Rapid identification of microorganisms from positive blood cultures by MALDI-TOF mass spectrometry subsequent to very short-term incubation on solid medium. Clin Microbiol Infect 2014;20:1001-6.
    Pubmed CrossRef