Publications (2)4.95 Total impact
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Article: Epidemiological and molecular characteristics of clinical isolates of Streptococcus pyogenes collected between 2005 and 2008 from Chinese children.
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ABSTRACT: The aim of this study was to explore the epidemiological and molecular characteristics of Streptococcus pyogenes in children from different cities in mainland China who were diagnosed with scarlet fever, impetigo and pharyngitis, as well as to detect asymptomatic carriers, between 2005 and 2008, and to compare the results with isolates from rural Chinese children with acute glomerulonephritis in 2005 and in the 1990s. Susceptibility tests to determine MICs and analysis of the presence of erythromycin-resistant genes (mefA, ermB and ermA) and emm gene typing were performed on 466 S. pyogenes isolates from Beijing, Shanghai, Chongqing and Shenzhen. Superantigen genes (speA and speC) were examined by performing PCR on isolates with the most prevalent emm genotype. All isolates were sensitive to penicillin, cefradine and ofloxacin. The highest rate of resistance was against clarithromycin (98.1 %), followed by erythromycin (97.6 %), azithromycin and clindamycin (both 97.2 %), and tetracycline (94.0 %). Among the 466 isolates, 421 (90.3 %) harboured the ermB gene, 145 (31.1 %) were speA-positive and 273 (58.6 %) were speC-positive. The speA gene was common in emm1.0 (88.8 %) and emm6.5 (83.3 %) genotypes. The speC gene was frequently observed in emm4.0 (90.0 %), emm12.0 (69.6 %), emm18.0 (66.7 %), emm22.0 (75.9 %) and emm80.0 (80.0 %) genotypes. The most prevalent emm genotypes in mainland China in recent years were emm1.0 and emm12.0. All isolates remained sensitive to β-lactams and quinolone.Journal of Medical Microbiology 03/2012; 61(Pt 7):975-83. · 2.50 Impact Factor -
Article: Molecular characterization of group G Streptococcus dysgalactiae subsp. equisimilis recovered from patients and healthy people in China.
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ABSTRACT: 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. equisimilis 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. equisimilis isolates to represent each emm type identified. These strains were further analyzed by pulsed-field gel electrophoresis (PFGE) typing. Sixteen emm 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. equisimilis emm types shared identical or nearly identical STs and subtypes of PFGE, demonstrating concordance between the emm 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.Diagnostic microbiology and infectious disease 11/2011; 72(1):41-6. · 2.45 Impact Factor
