Molecular characterization of group G Streptococcus dysgalactiae subsp equisimilis recovered from patients and healthy people in China

Beta-Hemolytic group G streptococci cause a considerable invasive disease burden and sometimes disease outbreaks. Little is known about the critical epidemiologic parameter of genetic relatedness between isolates. We determined the emm types of 65 Streptococcus dysgalactiae subsp. equisandis isolates. We formulated multilocus sequence typing (MLST) primers with 6 of the 7 loci corresponding to the Streptococcus pyogenes MLST scheme. We performed MLST with 69 S. dysgalactiae subsp. equisandis isolates to represent each elm type identified. These strains were further analyzed by pulsed-field gel electrophoresis (PFGE) typing. Sixteen emit: types were observed. Eighteen unique combinations of allelic profiles (sequence types [STs]) were obtained with 12 profiles each accounting for multiple isolates. Forty-one MLST STs were observed. Analysis of the PFGE patterns generated revealed 10 clones. Over 80% of the isolates were distributed in 3 large clones. Isolates within 16 redundantly represented S. dysgalactiae subsp. emm types shared identical or nearly identical STs and subtypes of PFGE, demonstrating concordance between the emu, type and genetic relatedness. It is conceivable that some particular characteristics in the genomes of these strains are responsible for their predominance in different regions. (C) 2012 Elsevier Inc. All rights reserved.