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Objective:To clarify the M protein ( emm gene) types and drug susceptibility characteristic variations of Group A Streptococcus (GAS) in children in Beijing. Methods:The GAS strains isolated from throat swab samples of children diagnosed with scarlet fever and pharyngeal infection in scarlet fever etiology surveillance sentinel hospitals in 16 districts of Beijing in 2018, 2019 and 2021 were analyzed retrospectively.PCR amplification and sequencing were used for emm genotyping, and the minimum inhibitory concentrations (MIC) of 10 antibiotics were determined by the broth microdilution method.The data were analyzed using χ2 test and Fisher′ s exact method between groups. Results:A total of 557 GAS strains were collected, and 11 emm genotypes ( emm1, emm3, emm4, emm6, emm11, emm12, emm22, emm75, emm89, emm128, and emm212) were detected.Of 557 strains, 238 trains were of emm1 type (42.73%), 271 strains were of emm12 type (48.65%) and 48 strains were of other emm types (8.62%). The detection rates of emm1, emm12 and other emm type genes in 2018, 2019, and 2021 were [37.50% (105/280 strains), 57.14% (160/280 strains), 5.36% (15/280 strains)], [49.05% (129/263 strains), 39.54% (104/263 strains), 11.41% (30/263 strains)], and [28.57% (4/14 strains), 50.00% (7/14 strains), 21.43% (3/14 strains)], respectively.In children infected with emm12 in 2018 and 2019, there were more children under 6 years old than children over 6 years old (62.50% vs.46.88%, 46.36% vs.30.36%) (χ 2=7.182, 6.973; all P<0.05). Drug susceptibility testing results suggested that 225 randomly selected GAS strains were all 100.00% sensitive to 7 antibiotics including Penicillin, Levofloxacin, Meropenem, Linezolid, Cefotaxime, Cefepime and Vancomycin.The rates of resistance to Erythromycin, Tetracycline and Clindamycin were [88.57% (93/105 strains), 87.62% (92/105 strains), 86.67% (91/105 strains)], and [94.34% (100/106 strains), 94.34% (100/106 strains), 87.74% (93/106 strains)] in 2018 and 2019, respectively.The test strains were 100.00% (14/14 strains) resistant to the above 3 antibiotics in 2021.MIC 50 and MIC 90 values of Penicillin in 2018, 2019, and 2021 were (0.03 mg/L, 0.03 mg/L), (0.03 mg/L, 0.06 mg/L), and (0.06 mg/L, 0.06 mg/L), respectively.Among 225 GAS strains, 207 strains had drug resistance and were resistant to more than one drug.Specifically, 94.69% (196/207 strains) were resistant to Erythromycin, Tetracycline and Clindamycin.About 4.35% (9/207 strains) were resistant to both Erythromycin and Clindamycin.A total of 0.97% (2/207 strains) were resistant to Erythromycin and Tetracycline. Conclusions:The emm genotypes of GAS in children in Beijing are diverse in 2018, 2019 and 2021.The dominant genotypes are emm12 and emm1, and emm12 is the main epidemiological type.GAS strains maintain highly resistant to Erythromycin, Clindamycin and Tetracycline, and sensitive to Penicillin and other antibiotics.However, MIC 50 and MIC 90 of Penicillin shows an ascending trend.
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Objective To reveal the genetic distribution of group A streptococcus progeny(GAS)isolated from children with re-spiratory tract infection in Beijing in 2015.Methods The throat swabs were collected from children with clinical diagnosis of scarlet fever and pharyngeal infection during May to July,2015.16 pediatric outpatient departments or pediatric emergency department of hospitals located in 16 districts of Beijing were enrolled in this study.PCR amplification and gene sequencing were employed.The encoding mature M protein gene(emm)distribution in different condition was compared and analyzed.Results A total of 247 GAS were isolated,including 73(29.6%,73/247)isolates from cases with scarlet fever and 174(70.4%,174/247)isolates from cases with pharyngeal infection.Among all isolates,six genotypes of emm were identified,including emm12(53.4%,132/247),emm1(44. 1%,109/247)and others(emm22,emm75,emm131 and emm241,2.5%,6/247).The significant difference of emm distribution with age was observed in this study:emm1 isolates were dominant in children aged 6-12,whereas emm12 isolates were dominant in chil-dren aged 1-5(P<0.05).While the emm distribution showed no significant difference in groups with different location,gender,and disease pattern(P>0.05).Conclusion Emm1 and emm12 were the circulating genotype of GAS in Beijing children,2015.Moreo-ver,the difference of distribution between emm1 and emm12 was proved in this study.
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Objective To explore the relationship between superantigen and M protein gene (emm)-types genes of Group A Streptococcus pyogenes (GAS) isolated from patients with scarlet fever in Beijing from May 2012 to July 2013 .Methods GAS was isolated from specimens of patients with scarlet fever . Superantigen genes (speA ,speB ,speC ,speF ,speG ,speH ,speI ,speJ ,speL ,speK ,speM ,ssa ,and smeZ) ,and emm gene were amplified by polymerase chain reaction .Rate and proportion were compared by chi-square test .Results Of the 423 GAS strains isolated from patients with scarlet fever from 2012 to 2013 ,most of the isolates possessed speB (97 .6% ) ,speC (99 .8% ) ,speF (98 .3% ) ,speG (99 .8% ) , smeZ (94 .1% ) and ssa (88 .4% ) ,and some of them possessed speH (54 .6% ) ,speI (53 .4% ) ,speA (45 .2% ) and speJ (43 .5% ) ,but very few isolates possessed speK (2 .4% ) ,speL (1 .4% ) and speM (1 .7% ) .Type emm12 (59 .5% ) and type emm1 (37 .4% ) were the main types of GAS .Most of the emm12-type isolates possessed speH (84 .8% ) and speI (84 .0% ) compared with only 4 .0% of speH and 3 .4% of speI in type emm1 .Most of type emm1 possessed speA (95 .3% ) and speJ gene (94 .6% ) compared with only 17 .3% of speA and 14 .8% of speJ in type emm12 .The superantigen genes profiles were significant different between emm 1-type and emm 12-type isolates (P< 0 .05) .Conclusion Type emm1 and type emm12 are epidemic strains in patients with scarlet fever from 2012 to 2013 in Beijing ,and emm gene-types are associated with superantigen genes profiles .
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BACKGROUND: Group A Streptococcus (GAS) is responsible for a wide spectrum of human diseases. We investigated the distribution of emm types and antibiotic resistance rates of GAS from clinical specimens in several Korean medical centers. METHODS: A total of 192 strains of GAS from throat, blood, and other specimens collected in Seoul, Busan, Ulsan, Iksan, and Jeju were studied in 2008-2009. The emm genotypes were identified using PCR and sequencing. Antimicrobial susceptibility testing was performed by disk diffusion method. Phenotypes of macrolide resistance were evaluated, and macrolide resistance genes were determined by PCR. RESULTS: The emm89 (33.9%) was most frequently detected, followed by emm1 (12.5%), emm12 (8.3%), emm4 (7.8%), and emm75 (7.3%). The distribution of emm types did not show a close relation to the type of specimen and was different for each area. The resistance rates to erythromycin (ERY) and clindamycin (CLI) were 4.6% and 3.7%, respectively. Among the nine ERY-resistant strains, the rate of constitutive resistance was 88.9%, compared with 11.1% for the M phenotype. Five of the ERY-resistant strains were emm28. CONCLUSION: This multicenter study reveals heterogenous emm genotypes by geographic area. Rates of resistance to ERY and CLI were low, and most of the ERY-resistant strains showed a constitutive macrolide-lincosamide-streptogramin B (cMLSB) phenotype.
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Humans , Clindamycin , Diffusion , Drug Resistance, Microbial , Erythromycin , Genotype , Korea , Molecular Epidemiology , Pharynx , Phenotype , Polymerase Chain Reaction , Streptococcus , Streptococcus pyogenesABSTRACT
Objective To investigate the distribution of the emm types and superantigens of group A streptococcal ( GAS) isolated from Chinese children. Methods Totally 222 GAS isolates collected from five Children's Hospitals of China during 2005～2006 were studied, emm types were performed by PCR and sequencing. The eight superan-tigen (SAg) genes (speA, speC, speH, speI, speG, speJ, ssa and SMEZ) were checked by PCR. Results Nine emm types were identified, of which emml2 (55. 86% ) and emml (39. 64% ) were the most prevalent types. The GAS isolates carried six or more SAg genes take 78. 39% of all the isolates in this study. The SAg gene profiles were closely associated with the emm type. Conclusion The emm type of S. pyogenes isolated from Chinese chil-dren was quite wide-spreading and SAg genes appeared to be associated with the emm type so its expression is po-tential in vaccine development.
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BACKGROUND: M protein is the major virulence factor of group A streptococci (GAS). As the emm gene, which encodes the M protein, has a variable sequence at 5'-terminus by each M type, it can be classified into several restriction-fragment length polymorphisms (RFLP) by restriction enzymes. Pulsed-field gel electrophoresis (PFGE) is useful for investigating clonal outbreaks or bacterial transmission. Molecular epidemiological analysis using emm-RFLP and PFGE was performed on GAS isolated from bacteremia. METHODS: Twenty-eight strains of GAS isolated from patients with bacteremia were included. Medical records of 27 cases were reviewed retrospectively to see the prognosis of GAS bacteremia. The restriction patterns of emm gene digested with HaeIII enzyme were compared by each emm genotype. Macrorestriction patterns were produced by PFGE after digestion of chromosomal DNA with SmaI and ApaI enzymes. RESULTS: All but 2 cases with toxic streptococcal syndrome survived. The DNA fragments of emm-HaeIII restriction showed 3 to 4 bands. Each emm genotype showed a different emm-HaeIII restriction pattern, except emm49 and SP2346, of which the restriction pattern was similar to that of emm1. Thirteen different PFGE patterns were observed by SmaI, and emm6, emm12, and emm75 were not cut with SmaI. All 28 strains were cut with ApaI, which yielded 17 different PFGE patterns. All but emm13 showed a high concordance between the PFGE patterns and the emm genotypes. CONCLUSIONS: The patients with GAS bacteremia showed a relatively good prognosis. We found that the restriction enzyme analysis of emm gene was rapid, simple and inexpensive to perform, and that PFGE was useful for classifying GAS strains because it generally discriminated well between each emm genotype. Although the number of strains studied was small, GAS bacteremia was not due to a single clone.