| Summary: | 碩士 === 中臺科技大學 === 醫學檢驗生物技術系碩士班 === 102 === Among group G streptococci (GGS), Streptococcus dysgalactiae subsp. equisimilis (SDSE) represents the most important human pathogen. According to the Central Laboratory of the Central Region Hospital Alliance, Taiwan, the isolation rate of SDSE is higher than group A Streptococcus (GAS) and SDSE becomes the most important clinical β-hemolytic streptococcal species. Biofilm formation plays a role in bacterial pathogenicity. It is known that biofilm facilitates the attachment of GAS to cell surface. However, no literature concerning the SDSE biofilm is available.
In this study, 246 clinical SDSE isolates from central Taiwan were collected. There were 73.2% (180/246) of isolates from non-sterile sites while the remainings were from normally sterile sites (26.8%, 66/246). Tryptic soy broth (TSB), brain heart broth (BHI), Todd-Hewitt broth (THB), and C medium with glucose (CGB) were respectively used to test biofilm formation, with a superior order of TSB, BHI, THB, and CGB found. For the association between emm type of SDSE and biofilm formation, stG10.0 and stG245.0 were positively correlated with biofilm formation (p=0.013 and 0.039, respectively). However, stG840.0 and stG6.1 were negatively associated with biofilm formation (p < 0.001 and 0.035, respectively). The biofilm formation rates of isolates form non-sterile sites and normally sterile sites were 52.2% (94/180) and 59.1% (39/66), respectively. No significant relationship between the specimen source and biofilm formation (p= 0.208) was revealed. To clarify the effect of glucose on biofilm formation, C medium and CGB were respectively used and glucose demonstrated to be positively correlated (p<0.001) with biofilm formation. Especially, adding of glucose was correlated with the biofilm formation of stG10.0, stG245.0, and stG6.1 types of SDSE ( p =0.017, 0.001, and 0.004, respectively). FCT region-encoded pilus facilitates biofilm formation in GAS. FCT-like region of SDSE was analyzed by PCR with 11 FCT types found. The rate of FCT type 1 reached 83.7% (206/246). No significant relationship between the FCT type 1 and biofilm formation (p=0.23) was found, however, FCT type 1 was positively correlated with stG10.0 ( p <0.001) and negatively associated with stG245.0 ( p <0.001). In addition, the present of spegg gene and ska gene were no significant correlations with biofilm formation ( p =0.450 and 0.064, respectively).
This is the first study investigating biofilm-forming potential and FCT types of clinical SDSE isolates. Also, the associations between biofilm-forming potential, FCT type and emm type of SDSE were presented.
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