Abstract:In this study, we aimed to evaluate the clinical application values of matrix-assisted laser desorption ionization time of flight mass spectrometry (MALDI-TOF MS) for Salmonella identification and investigate its influencing factors. All Salmonella isolates were serotyped by traditional serological method. Salmonella isolates were cultured for 24, 72, 120 and 168 h in Columbia blood agar, Hektoen Enteric (HE) agar, Salmonella Shigella (SS) agar and MacConkey (MAC) agar respectively. And then the strains were identified by MALDI-TOF MS. Thirty-eight serotypes were identified among 179 Salmonella strains and the top three serotypes were Salmonella enteritidis (21.2%), Salmonella stanley (17.3%) and SalmonellaⅠ4,5,12:i:-(16.2%). All isolates cultured in blood agar, HE agar, SS agar and MAC agar for 24 h and 72 h could be correctly identified by MALDI-TOF MS. The consuming cost of MALDI-TOF MS was about one third of microbial automatic biochemical identification system (Vitek 2) and its detection time was one seventh of Vitek 2. Salmonella cultured in Columbia blood agar, Hektoen Enteric agar, Salmonella Shigella agar and MacConkey agar within three days could be correctly identified by MALDI-TOF MS. Compared with Vitek 2, MALDI-TOF MS provided a faster and lower-cost method that could also directly identify Salmonella isolates cultured in selective medium.
[1] Majowicz SE, Musto J, Scallan E, et al. The global burden of nontyphoidal Salmonella gastroenteritis[J]. Clin Infect Dis, 2010, 50(6): 882-889. doi:10.1086/650733 [2] Seng P, Drancourt M, Gouriet F, et al. Ongoing revolution in bacteriology: routine identification of bacteria by matrix-assisted laser desorption ionization time-of-flight mass spectrometry[J]. Clin Infect Dis, 2009, 49(4): 543-551. doi:10.1086/600885 [3] Bader O, Weig M, Taverne-Ghadwal L, et al. Improved clinical laboratory identification of human pathogenic yeasts by matrix-assisted laser desorption ionization time-of-flight mass spectrometry[J]. Clin Microbiol Infect, 2011, 17(9): 1359-1365. doi:10.1111/j.1469-0691.2010.03398.x [4] Chao QT, Lee TF, Teng SH, et al. Comparison of the accuracy of two conventional phenotypic methods and two MALDI-TOF MS systems with that of DNA sequencing analysis for correctly identifying clinically encountered yeasts[J]. PLoS One, 2014, 9(10): e109376. doi:10.1371/journal.pone.0109376 [5] Valentine N, Wunschel S, Wunschel D, et al. Effect of culture conditions on microorganism identification by matrix-assisted laser desorption ionization mass spectrometry[J]. Appl Environ Microbiol, 2005, 71(1): 58-64. doi:10.1128/AEM.71.1.58-64.2005 [6] Martiny D, Visscher A, Catry B, et al. Optimization of Campylobacter growth conditions for further identification by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS)[J]. J Microbiol Methods, 2013, 94(3): 221-223. doi:10.1016/j.mimet.2013.06.018 [7] Wieser A, Schneider L, Jung J, et al. MALDI-TOF MS in microbiological diagnostics-identification of microorganisms and beyond (mini review)[J]. Appl Microbiol Biotechnol, 2012, 93(3): 965-974. doi:10.1007/s00253-011-3783-4 [8] Dieckmann R, Helmuth R, Erhard M, et al. Rapid classification and identification of Salmonellae at the species and subspecies levels by whole-cell Matrix-assisted laser desorption ionization-time of flight mass spectrometry[J]. Appl Environ Microbiol, 2008, 74(24): 7767-7778. doi:10.1128/AEM.01402-08 [9] Balazova T, Makovcova J, Sedo O, et al. The influence of culture conditions on the identification of Mycobacterium species by MALDI-TOF MS profiling[J]. FEMS Microbiol Lett, 2014, 353(1): 77-84. doi:10.1111/1574-6968.12408 [10] Chen XJ, Yun HH, Kuang H, et al. Studies on the protein fingerprint of Salmonella by MALDI-TOF-MS[J]. Food Sci Biotech, 2012(11): 1189-1197. (in Chinese) 陈秀金,尹红红,匡华,等. 沙门氏菌MALDI-TOF-MS蛋白质指纹图谱分析方法的研究[J]. 食品与生物技术学报, 2012(11): 1189-1197.