中臺灣β溶血性G群Streptococcus dysgalactiae subsp. equisimilis臨床分離株毒力因子的分佈

Abstract

Group G streptococci (GGS) are causative agents of bacteremia, pharyngitis, cellulitis, endocarditis, and streptococcal toxic shock syndrome. The clinical importance of GGS is increasing. Among GGS, Streptococcus dysgalactiae subsp. equisimilis (SDSE) is the major human pathogen. In recent years, the frequency of GGS infections in central Taiwan was higher than that of group A streptococci (GAS). Many studies have revealed that SDSE probably obtained genes encoding virulence factors of GAS via horizontal transfer. In this study, 291 GGS isolates were collected from the Fong-Yuan Hospital and Lin-Shin Hospital. By 16S rRNA gene sequencing, 246 isolates (84.5%) were identified as SDSE, 22 (7.6%) as S. anginosus, 5 (1.7%) as S. constellatus, while 18 isolates (6.2%) were non-GGS. SDSE is the most common GGS in central Taiwan. By emm typing, the most prevalent emm types were stG10.0 (98/246, 39.8%), stG245.0 (38/246, 15.4%), stG840.0 (30/246, 12.2%), stG6.1 (19/246, 7.7%), and stG652.0 (10/246, 4.1%), respectively. The prevalence of emm types among SDSE isolates in central Taiwan differed from other countries or regions. Two new emm subtypes, stG840.1 and stG351.1, were first found in this study. By PCR or multiplex real-time PCR, it was found that lmb (encoded laminin-binding protein), sagA (encoded streptolysin S) and gapC (encoded glyceraldehyde 3-P dehydrogenase) genes existed in all SDSE isolates. The slo (encoded streptolysin O) gene detected in 99.2% (244/246) of isolates and the ska (encoded streptokinase) gene existed in 72.8% (179/246) of isolates. Except for 74.4% (183/246) of isolates with spegg (encoded streptococcus pyrogenic exotoxin Gdys), whereas all isolates were negative for other superantigens. By chi square test the presence of the spegg gene was positive correlations with emm types stG10.0 and stG840.0. The presence of the spegg gene was negative correlations with emm types stG245.0, stG6.1 and stG652.0. The presence of the ska gene was positive correlations with emm types stG6.1 and stG652.0. The presence of the ska gene was negative correlation with emm type stG10.0. This is the first study concerning the virulence factors distribution among β-hemolytic group G SDSE isolates in central Taiwan.