MALDI-TOF mass spectrometry-based identification of group A Streptococcus isolated from areas of the 2011 scarlet fever outbreak in china
2013
Xiao, Di | You, Yuanhai | Bi, Zhenwang | Wang, Haibin | Zhang, Yongchan | Hu, Bin | Song, Yanyan | Zhang, Huifang | Kou, Zengqiang | Yan, Xiaomei | Zhang, Menghan | Jin, Lianmei | Jiang, Xihong | Su, Peng | Bi, Zhenqiang | Luo, Fengji | Zhang, Jianzhong
There was a dramatic increase in scarlet fever cases in China from March to July 2011. Group A Streptococcus (GAS) is the only pathogen known to cause scarlet fever. Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) coupled to Biotyper system was used for GAS identification in 2011. A local reference database (LRD) was constructed, evaluated and used to identify GAS isolates. The 75 GAS strains used to evaluate the LRD were all identified correctly. Of the 157 suspected β-hemolytic strains isolated from 298 throat swab samples, 127 (100%) and 120 (94.5%) of the isolates were identified as GAS by the MALDI-TOF MS system and the conventional bacitracin sensitivity test method, respectively. All 202 (100%) isolates were identified at the species level by searching the LRD, while 182 (90.1%) were identified by searching the original reference database (ORD). There were statistically significant differences with a high degree of credibility at species level (χ2=6.052, P<0.05 between the LRD and ORD). The test turnaround time was shortened 36–48h, and the cost of each sample is one-tenth of the cost of conventional methods. Establishing a domestic database is the most effective way to improve the identification efficiency using a MALDI-TOF MS system. MALDI-TOF MS is a viable alternative to conventional methods and may aid in the diagnosis and surveillance of GAS.
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