Correlation of the emm genotyping and virulence genes with the isolation sites of Group A Streptococcus strains from children with impetigo / 中华实用儿科临床杂志

Objective:To investigate the correlation of the emm genotypes and virulence genes with the isolation sites of Group A Streptococcus (GAS). Methods:It was a retrospective study.The specimens were collected from children with impetigo in Beijing Children′s Hospital, Capital Medical University from 2006 to 2008 for GAS isolation and identification.A total of 24 GAS strains were isolated from 16 children with impetigo, among which 7 pairs of strains were isolated from the throat and skin of 7 children, and 1 pair of strains was isolated from the vulva and skin of one child, and the remaining 8 GAS strains were isolated from the skin pus samples of 8 children.Polymerase chain reaction was applied to detect the emm genotypes and 13 virulence genes ( speA, speB, speC, speF, speG, speH, speI, speJ, speK, speL, speM, smeZ and ssa). The correlation of the emm genotypes and virulence genes with the isolation sites of GAS strains was analyzed. Results:In this study, four emm genotypes were detected, including emm1.0 (15/24), emm12.0 (4/24), emm22.0 (2/24) and emm160.0 (1/24), and one subtype emm12.19 (2/24) was detected as well.The carrying rates of 13 virulence genes speA, speB, speC, speF, speG, speH, speI, speJ, speK, speL, speM, smeZ and ssa were 58.3%, 100%, 91.7%, 100%, 50.0%, 12.5%, 54.2%, 66.7%, 16.7%, 25.0%, 12.5%, 100% and 91.7%, respectively.All strains carried 5 to 11 virulence genes and they all carried speB, speF and smeZ.There were significant differences in the carrying rate of speA and speJ among the strains with different emm genotypes (all P<0.05). There was no significant difference in the distribution of virulence genes between skin isolates and pharyngeal isolates, including the 5 pairs of strains carrying the emm1.0 genotype (all P>0.05). Conclusions:The distribution of virulence gene of GAS in children with impetigo is significantly correlated with the emm genotype, rather than the isolation site.

Distribution characteristics of emm genotype and superantigen of Group A Streptococcus isolated from the pharynx of children with scarlet fever-like erythema in Beijing / 中华实用儿科临床杂志

Objective:To analyze the genetic characteristics of Group A Streptococcus (GAS) isolated from the pharynx of children with scarlet fever-like erythema. Methods:Pharyngeal GAS isolates were collected retrospectively from children with scarlet fever-like erythema admitted in the Department of Dermatology, Beijing Children′s Hospital, Capital Medical University from June 2019 to February 2020.PCR and sequencing were used to detect emm genotyping and superantigen genes( speA, speB, speC, speF, speG, speH, speI, speJ, speK, speL, speM, ssa and smeZ) of the isolates.Data were compared by the chi-square test or Fisher′ s exact test between groups. Results:A total of 147 GAS strains were collected.The main emm genotypes were emm1.0 in 76 strains (51.70%) and emm12.0 in 60 strains (40.82%). Other 7 emm genotypes were all found in less than 5 strains.The detection rate of speF, smeZ, speG, speC, speB and ssa were as high as 100.00%(147/147 strains), 100.00%(147/147 strains), 99.32%(146/147 strains), 95.24%(140/147 strains), 94.56%(139/147 strains) and 92.52%(136/147 strains), respectively. speA, speJ, speI, speH and speM had a low detection rate of 51.70%(76/147 strains), 49.66%(73/147 strains), 32.65%(48/147 strains), 23.81%(35/147 strains) and 4.08%(6/147 strains), respectively.No speK and speL were detected.The frequencies of speA and speJ in emm1.0 strains (65/76 strains, 85.53% and 64/76 strains, 84.21%) were significantly higher than those in emm12.0 strains (4/60 strains, 6.67% and 6/60 strains, 10.00%). However, the frequencies of speH and speI in emm1.0 strains (7/76 strains, 9.21% and 2/76 strains, 2.63%) were significantly lower than those in emm12.0 strains (28/60 strains, 46.67% and 45/60 strains, 75.00%) (all P<0.001). Conclusions:At present, emm1.0 and emm12.0 are the main GAS strains isolated from the throat of children with scarlet fever-like erythema in Beijing, and emm1.0 is more common.There is a correlation between emm genotyping and the superantigen gene profile.Type 1 superantigen gene profile is significantly more frequently detected in emm1.0 strains than in emm12.0 strains.Type 2, 3 and 4 superantigen gene profiles are significantly more frequently detected in emm12.0 strains than in emm1.0 strains.

Molecular Epidemiological Features and Antibiotic Susceptibility Patterns of Streptococcus dysgalactiae subsp. equisimilis Isolates from Korea and Japan

BACKGROUND: The molecular characterization of Streptococcus dysgalactiae subsp. equisimilis (SDSE) has not yet been performed in Korea. This study aimed to find the differences or similarities in the clinical features, molecular epidemiological findings, and antimicrobial resistance patterns of SDSE from two countries (Korea and Japan). METHODS: SDSE isolates were collected from Korea (N=69) from 2012–2016 and Japan (N=71) from 2014–2016. Clinical characteristics, emm genotypes, and sequence types (STs) were compared. Microdilution tests were performed using different antimicrobials, and their resistance determinants were screened. RESULTS: Median ages were 69 years in Korea and 76 years in Japan. The most common underlying diseases were diabetes and malignancy. Blood-derived isolates comprised 36.2% and 50.7% of Korean and Japanese isolates, respectively; mortality was not different between the two groups (5.8% vs 9.9%, P=0.53). Among Korean isolates with 20 different combined ST-emm types, ST127-stG245 (N=16), ST128-stG485 (N=10), and ST138-stG652 (N=8) were prevalent. Among Japanese isolates with 29 different combined types, ST17-stG6792 (N=11), ST29-stG485 (N=7), and ST205-stG6792 (N=6) were prevalent. Resistance rates to erythromycin, clindamycin, and minocycline were 34.8%, 17.4%, and 30.4% in Korea and 28.2%, 14.1%, and 21.4% in Japan, respectively. CONCLUSIONS: SDSE infections commonly occurred in elderly persons with underlying diseases. There was a significant difference in the distribution of ST-emm types between the two countries. Antimicrobial resistance rates were comparable with different frequencies of resistance determinants in each country.

Genotypic and Phenotypic Analysis Among Clinical Isolate of Streptococcus pyogenes in Seoul , Korea

A total of 152 strains of Streptococcus pyogenes were isolated from patients with pharyngitis, scarlet fever, skin infection, or invasive streptococcal infections in Seoul, Korea from January 1988 to December 1999. All isolates were epidemiologically characterized to decide phenotypes by T protein serotype and serum opacity factor (OF) detection. Genetic diversity of the isolates were analyzed by emm genotyping and pulsed-field gel electrophoresis (PFGE). T protein serotype showed 17 kinds in distribution and T12 (40.1% of study strains), T4 (19.1%), and T1 (7.9%) were the prevalent ones. When sources of S. pyogenes isolates were analyzed by T serotype distribution, T12 type was predominant in pharyngitis and skin infection isolates which contributed to 30 strains (49.2%) and 11 strains (18.0%), respectively. When T serotype of S. pyogenes isolates were analyzed by emm genotype distribution, of the 61 isolates of T12 type, 48 strains (78.7%) belonged to the emm type 12 (M12) and of the 29 isolates of T4 type, 27 strains (93.1%) belonged to the emm genotype 4 (M4). PFGE of genomic DNA of different emm genotype (emm12, emm4 and emm1) showed distinctive patterns. When the DNA of same emm gene type isolates were analyzed genetic relatedness by PFGE pattern, emm4, emm1, and emm12 types showed over 90%, 75%, and 70% of genetic similarity, respectively. Therefore, it was suggested that these emm genotype isolates were closely related genetically whereas among the isolates of other emm genotypes showed less than 30% of genetic similarity. Show genotypes are more diverse in comparison with phenotypes. In even epidemiologically unrealated isolates, genetic subtypes appeared correlated. The phenotypic and genotypic analysis used in the study were discriminative and appropriate for epidemiological study of S. pyogenes.