Biological characteristics and genomic features of Streptococcus pyogenes isolated from a child with atypical brain abscess
10.3760/cma.j.cn112309-20241202-00411
- VernacularTitle:1株非典型脑脓肿患儿分离化脓链球菌的生物学特征和基因组特征
- Author:
Jinsi ZHOU
1
;
Weilin HU
;
Chunzhen HUA
;
Mingming ZHOU
;
Yuanhai YOU
Author Information
1. 浙江大学医学院附属儿童医院感染科，杭州 310051
- Publication Type:Journal Article
- Keywords:
Streptococcus pyogenes;
Whole-genome sequencing;
Virulence factor
- From:
Chinese Journal of Microbiology and Immunology
2025;45(3):223-230
- CountryChina
- Language:Chinese
-
Abstract:
Objective:To analyze the biological characteristics and genomic features of a Streptococcus pyogenes strain isolated from the pus of a child with an atypical brain abscess. Methods:The Streptococcus pyogenes strain, named 21SPY7071 ( emm22 type), was isolated from the brain abscess specimen of a child undergoing surgery for brain abscess. The biological characteristics of this strain were analyzed using blood agar culture, Gram staining, growth curve measurement, and hemolytic analysis. After whole-genome sequencing, core genome multilocus sequence typing (cgMLST) was performed to analyze the cgST type of the strain, and the distribution of virulence genes and drug resistance genes were analyzed. qRT-PCR was used to detect the differences in the expression of virulence genes at mRNA level between the strain 21SPY7071 and two Streptococcus pyogene strains of ATCC 19615 ( emm80 type) and GAS029 ( emm22 type, clinical isolate). Results:The strain 21SPY7071 was a Gram-positive Streptococcus with atypical weak β-hemolysis. Whole-genome sequencing and cgMLST revealed that this isolate belonged to the cgST type of 65937, containing 187 virulence genes and 97 drug resistance genes, with high sequence similarity (95.16%~100.00%) to the main virulence factor-encoding genes in the Virulence Factor Database. Compared with the strains of ATCC 19615 and GAS029, the strain 21SPY7071 showed reduced expression of genes encoding streptolysin S ( sagABCDEFGHI), streptolysin O ( slo), and hyaluronate lyase ( endA/ sdaB). Besides, compared with the strain ATCC 19615, the strain 21SPY7071 also showed decreased expression of virulence genes including speG, ideS/ mac, hylA, smeZ, lmb, and scpA/ scpB. Conclusion:This Streptococcus pyogenes strain isolated from the pus of a child with atypical brain abscess exhibits weak hemolysis and lower expression of virulence genes, which may be related to the mild clinical symptoms observed in the child.
