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You Y.,Chinese National Institute for Communicable Disease Control and Prevention | You Y.,Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases | Wang H.,Center for Disease Control and Prevention of Chaoyang district of Beijing | Bi Z.,Institute of Bacterial Infectious Diseases | And 16 more authors.
Molecular and Cellular Probes | Year: 2015

Streptococcus pyogenes causes human infections ranging from mild pharyngitis and impetigo to serious diseases including necrotizing fasciitis and streptococcal toxic shock syndrome. The objective of this study was to compare molecular emm typing and pulsed field gel electrophoresis (PFGE) with multiple-locus variable-number tandem-repeat analysis (MLVA) for genotyping of Chinese S.pyogenes isolates. Molecular emm typing and PFGE were performed using standard protocols. Seven variable number tandem repeat (VNTR) loci reported in a previous study were used to genotype 169. S. pyogenes geographically-diverse isolates from China isolated from a variety of disease syndromes. Multiple-locus variable-number tandem-repeat analysis provided greater discrimination between isolates when compared to emm typing and PFGE. Removal of a single VNTR locus (Spy2) reduced the sensitivity by only 0.7%, which suggests that Spy2 was not informative for the isolates screened. The results presented support the use of MLVA as a powerful epidemiological tool for genotyping S.pyogenes clinical isolates. © 2015 Elsevier Ltd. Source


Xiao D.,Chinese National Institute for Communicable Disease Control and Prevention | You Y.,Chinese National Institute for Communicable Disease Control and Prevention | Bi Z.,Institute of Bacterial Infectious Diseases | Wang H.,Center for Disease Control and Prevention of Chaoyang district of Beijing | And 12 more authors.
Infection, Genetics and Evolution | Year: 2013

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. © 2013 Elsevier B.V. Source

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