Ling Zhu, Xiangchen Li, Lili Zheng, Lihua Zhou, Zhenfa Chen, Yibin Lin, Jianhua Zhu, Junshun Gao, Junli Gao, Yunxiang Cai, Xinhua Qiang
Among 188 NTS isolates, 35 serotypes and 36 STs were identified. Three STs predominated: ST34 (26.1%, mainly monophasic S. Typhimurium), ST11 (15.4%, exclusively S. Enteritidis), and ST19 (13.3%, classical S. Typhimurium). ST34 showed significantly enhanced epithelial adhesion in IEC-6 cells, whereas increased invasion was observed only in comparison with ST11 and not with ST19. Comparative genomics and transcriptomics identified an intact Gifsy-1 prophage as an ST34-specific genetic element encoding the T3SS effectors GogB and SteE/SarA, with gogB and steE/sarA being the only virulence genes consistently upregulated in ST34 versus both ST11 and ST19. Protein-protein interaction network analysis positioned these effectors as peripheral components of a 14-member prophage-associated module. All 49 ST34 isolates carried the intact Gifsy-1 prophage, whereas ST19 isolates harbored only truncated versions and ST11 completely lacked this element. ST34 also carried a broad antimicrobial resistance gene repertoire, including frequent tetracycline and sulfonamide resistance determinants and sporadic detection of clinically important beta-lactamase genes.
INTRODUCTION: Non-typhoidal Salmonella (NTS) is a leading cause of bacterial gastroenteritis worldwide, yet the pathogenic differences among co-circulating dominant clones remain poorly understood.
METHODS: A 7.5-year surveillance study (2017-2024) was conducted using NTS isolates from patients with acute diarrheal illness in Huzhou, China. Quantitative IEC-6 cell-based adhesion and invasion assays, comparative genomics, transcriptomic profiling, and protein-protein interaction network analysis were integrated to compare the dominant sequence types (STs).
RESULTS: Among 188 NTS isolates, 35 serotypes and 36 STs were identified. Three STs predominated: ST34 (26.1%, mainly monophasic S. Typhimurium), ST11 (15.4%, exclusively S. Enteritidis), and ST19 (13.3%, classical S. Typhimurium). ST34 showed significantly enhanced epithelial adhesion in IEC-6 cells, whereas increased invasion was observed only in comparison with ST11 and not with ST19. Comparative genomics and transcriptomics identified an intact Gifsy-1 prophage as an ST34-specific genetic element encoding the T3SS effectors GogB and SteE/SarA, with gogB and steE/sarA being the only virulence genes consistently upregulated in ST34 versus both ST11 and ST19. Protein-protein interaction network analysis positioned these effectors as peripheral components of a 14-member prophage-associated module. All 49 ST34 isolates carried the intact Gifsy-1 prophage, whereas ST19 isolates harbored only truncated versions and ST11 completely lacked this element. ST34 also carried a broad antimicrobial resistance gene repertoire, including frequent tetracycline and sulfonamide resistance determinants and sporadic detection of clinically important beta-lactamase genes.
DISCUSSION: These findings identify an intact Gifsy-1 prophage encoding GogB and SteE/SarA as a candidate module associated with enhanced epithelial adhesion in ST34, a dominant NTS lineage with an extensive antimicrobial resistance repertoire.