Prevalence of Complement-Mediated Cell Lysis-like Gene (sicG) in Streptococcus dysgalactiae subsp. equisimilis Isolates From Japan (2014–2016)

BACKGROUND: Streptococcus dysgalactiae subsp. equisimilis (SDSE; a β-hemolytic streptococcus of human or animal origin) infections are emerging worldwide. We evaluated the clonal distribution of complement-mediated cell lysis-like gene (sicG) among SDSE isolates from three central prefectures of Japan. METHODS: Group G/C β-hemolytic streptococci were collected from three institutions from April 2014 to March 2016. Fifty-five strains (52 from humans and three from animals) were identified as SDSE on the basis of 16S rRNA sequencing data.; they were obtained from 25 sterile (blood, joint fluid, and cerebrospinal fluid) and 30 non-sterile (skin-, respiratory tract-, and genitourinary tract-origin) samples. emm genotyping, multilocus sequence typing, sicG amplification/sequencing, and random amplified polymorphic DNA (RAPD) analysis of sicG-positive strains were performed. RESULTS: sicG was detected in 30.9% of the isolates (16 human and one canine) and the genes from the 16 human samples (blood, 10; open pus, 3; sputum, 2; throat swab, 1) and one canine sample (open pus) showed the same sequence pattern. All sicG-harboring isolates belonged to clonal complex (CC) 17, and the most prevalent emm type was stG6792 (82.4%). There was a significant association between sicG presence and the development of skin/soft tissue infections. CC17 isolates with sicG could be divided into three subtypes by RAPD analysis. CONCLUSIONS: CC17 SDSE harboring sicG might have spread into three closely-related prefectures in central Japan during 2014–2016. Clonal analysis of isolates from other areas might be needed to monitor potentially virulent strains in humans and animals.

Decline in Erythromycin Resistance in Group A Streptococci from Acute Pharyngitis due to Changes in the emm Genotypes Rather Than Restriction of Antibiotic Use / 대한진단검사의학회지

BACKGROUND: Group A streptococcus (GAS) is the most common cause of bacterial pharyngitis in children. Antibiotic resistance rates and emm genotypes of GAS isolated from patients with acute pharyngitis were studied in 2009. METHODS: Throat cultures were taken from 499 children with acute pharyngitis in Jinju, Korea, in 2008-2009. A total of 174 strains (34.9%) of GAS were isolated, and antimicrobial susceptibility testing was performed using the disk diffusion method. The phenotypes of macrolide resistance and macrolide resistance genes were determined. The emm genotypes were identified using PCR and sequencing. The data were compared with those acquired in 2002 in the same region. Data on the annual macrolide production were collected between 1999 and 2008. RESULTS: The resistance rates of GAS to erythromycin, clindamycin, and tetracycline were 4.6%, 2.9%, and 2.3%, respectively. The constitutive resistance rate was 62.5% for the erm(B) gene and 37.5% for the M phenotype of the mef(A) gene. emm4 was most frequently detected (28.2%), followed by emm89 (20.1%). Most of the erythromycin resistant strains had the emm28 genotype. We noted a gradual increase in macrolide production during the study period. CONCLUSIONS: The erythromycin resistance rate of GAS isolated from children with acute pharyngitis was significantly lower in 2009 (4.6%) than in 2002 (44.8%). We observed a remarkable change in the distribution of emm genotypes during the 7-yr period. The significant decline in erythromycin resistance in 2009 might be associated with a prominent decrease in the resistant genotype emm12 (3.4% in 2009 vs. 28.0% in 2002) rather than restriction of macrolide use.

Distribution of T types and emm Genotypes of Streptococcus pyogenes in Jinju, 2004 / 대한진단검사의학회지

BACKGROUND: T antigens and emm genotypes are useful markers for epidemiologic investigation of Streptococcus pyogenes infections. Epidemiologic studies of S. pyogenes were performed on a large scale in Jinju. This was the third study being carried out in the same area over the past 10 years. METHODS: A total of 328 S. pyogenes were isolated from throat cultures obtained from asymptomatic schoolchildren in the Jinju area in 2004. T typing was performed by a slide agglutination, and emm genotyping by PCR and DNA sequencing. We compared the results of this study with those of the previous ones performed in 1995 and 2002. RESULTS: T5/27/44 were the most prevalent, accounting for 29.6% of all isolates; T12 and T6 were 13.4% and 10.7%, respectively, and T nontypeable was 3.4%. The emm44/61 type was the most prevalent accounting for 29.3%, and emm6 and emm1 were 11.6% and 9.8%, respectively. CONCLUSIONS: Newly recognized T5/27/44 and emm44/61 were the most prevalent, accounting for about 30% of all isolates, while T12 and emm12 were significantly decreased in 2004 compared to the results of previous years. This study demonstrated divergent features of S. pyogenes epidemiology over the past 10 years in the Jinju area.

Association of T Antigens with emm Genotypes of Group A Streptococci / 대한임상미생물학회지

BACKGROUND: T typing has been used as a screening test for epidemiologic studies of group A streptococci (GAS) infections or carriers, and M typing has been performed for virulence studies. However, M typing is difficult to perform in routine laboratories. Recently, genotyping of the emm gene, which encodes the M protein, has become available. We investigated which T antigen is closely associated with a certain emmgenotype. METHODS: GAS were collected from the children in Jinju who were asymptomatic carriers (N=349) or had acute pharyngitis (N=122) during the 3 year-period from 2002 through 2004. T typing was performed by a slide aggulutination, and emmgenotyping by PCR and DNA sequencing. RESULTS: More than 90% of T1, T3, T6, T12, T25, and T5/27/44 antigens were associated with emm1, emm3, emm6, emm12 and 22, emm75, and emm44/61 genotypes, respectively; however, other T antigens, such as T2, T4, T7, T11, and B3264, were not associated with any particular emm genotypes. CONCLUSION: Several T antigens are so closely associated with particular emm genotypes that one could predict emmgenotypes based on the result of T typing.

Genotype Analysis of Pyrogenic Exotoxin and emm Genes of Streptococcus pyogenes Clinical Isolates

A variety of proteins produced by Streptococcus pyogenes contribute to the virulence of the pathogen. Among the proteins, the M protein and streptococcal pyrogenic exotoxins (Spe) are considered the major S. pyogenes virulence factors. To better characterize the correlation of M protein type and pyrogenic exotoxins with clinical diseases, we tested 269 S. pyogenes clinical isolates from patients with scarlet fever, pharyngitis, skin infection, otitis media, or other invasive streptococcal infections that provided appropriate clinical data. The strains were genotyped (M type) and assayed for speA, speB, and speC genes. The speB gene was detected in all isolates. Also, speA and speC genes were detected in 54 strains (18.2%) and 140 strains (47.3%), respectively. The strains isolated from invasive disease patients showed the highest frequency of speA gene (40.5%). The correlation among emm genotype, speA gene, and clinical patterns was analyzed. Genotypes emm1 (55.6%) and emm3 (22.2%) were predominant in stains with speA gene. The distribution of emm genotypes did not significantly associate with clinical patterns. These data suggest that SpeA is significantly associated with specific emm genotypes, and the exotoxin serve a dominant virulence factor.

Epidemiological Surveillance of Group A Streptococci Isolated from School Children Using emm Genotyping / 대한진단검사의학회지

BACKGROUND: Group A streptococci (GAS), the most common cause of bacterial pharyngitis, can be spread by interpersonal contact. While T typing is useful for screening, it does not completely identify organisms for epidemiological studies. The M protein is the most important virulence marker but has a drawback for epidemiological studies in that it is difficult to maintain the more than 80 necessary kinds of sera. The emm gene, which encodes the M protein, has variable sequences at the 5' N terminus, and emm genotyping using PCR and automatic sequencing has been reported lately. METHODS: Beta-hemolytic streptococci (BHS) were isolated from the throats of elementary school children in Jinju. T typing and emm genotyping was performed and compared with the T and M typing results of 1995. RESULTS: One hundred seventeen (20.1%) from 581 children yielded BHS, of which 83.8% were group A. T non-typeable strains were the most common (43.9%) and T12 was next (27.6%). The emm 12 was most frequent (33.7%), and emm 75 (10.2%), emm 18 (9.2%), emm 22 (8.2%), and emm 1 (7.1%) were relatively common. emm 2, 18, 50 and 75 were newly recognized. The isolation rate of BHS was 32.4% of which 57.1% was group A in 1995. T12 (44.7%) and T28 (13.2%) were the most common, and M12 (26.3%) and M28 (10.5%) were frequently identified in 1995. CONCLUSIONS: GAS was relatively common in school children. The distribution of the T antigen did not change significantly except for the T non-typeable since 1995. emm genotypes were diverse and emm 2, 18, 50 and 75 were newly recognized. Continuous microbiologic and epidemiological surveillance for GAS should be conducted in the community.

M-Protein Genotyping and Exotoxin A Production of Group A Streptococci Isolated from Blood / 대한임상병리학회지

BACKGROUNDS: While M protein is the most important virulence factor of group A -hemolytic streptococci (GAS), the routine laboratories have difficulty to maintain more than 80 kinds of antibodies. emm gene encoding M protein has variable sequence at 5'-terminus according to each M type and is an appropriate target for molecular typing of GAS. Molecular epidemiologic analysis using emm gene sequencing and serological typing were conducted for GAS isolated from bacteremic patients. Also production of streptococcal pyrogenic exotoxin A (SPE A), a well known virulence factor in toxic streptococcal syndrome, and the frequency of speA and speB gene for the strains were observed. METHODS: Twenty-eight strains of GAS isolated from blood specimens were analyzed with serological or molecular typing. Serological typing including T antigen and serum opacity reaction was processed by standard methods. 5' region of emm PCR products was analyzed by automatic DNA sequencer. The obtained DNA sequences were matched with GenBank. Production of SPE A was confirmed by Western blot and the frequencies of spe genes were analyzed by PCR. RESULTS: All GAS strains were well classified into 13 kinds of different emm genotypes. emm13 (18%) was most common and emm1 and emm3 were three and two strains respectively. Discrepancy between T typing and emm genotyping was observed in two strains. speA gene and SPE A toxin were positive in six over 28 strains, of which emm types were emm1, emm3 and SP2346. CONCLUSION: In the distribution of emm genotypes of GAS isolated from blood, emm13 was the most common genotype, of which finding is quite different from the results of foreign countries. Virulent types such as emm1 (11%) and emm3 (7%) genotypes were not uncommon, which were positive in speA gene and SPE A toxin.