Boueroy Parichart, Brizuela Jaime, Roodsant Thomas J, Wongsurawat Thidathip, Jenjaroenpun Piroon, Chopjitt Peechanika, Hatrongjit Rujirat, Phetburom Nattamol, Chareonsudjai Sorujsiri, Boonmars Thidarut, Schultsz Constance, Kerdsin Anusak
Faculty of Public Health, Kasetsart University Chalermphrakiat Sakon Nakhon Province Campus, Sakon Nakhon, Thailand.
Amsterdam UMC Location University of Amsterdam, Department of Global Health, Amsterdam Institute for Global Health and Development, Paasheuvelweg 25, Amsterdam, The Netherlands.
Eur J Clin Microbiol Infect Dis. 2025 Mar;44(3):639-651. doi: 10.1007/s10096-024-05029-w. Epub 2024 Dec 28.
Streptococcus suis serotype 14 is the second most prevalent serotype being highly prevalent in Southeast Asia. This study aimed to characterize genetic background, population structure, virulent genes, antimicrobial-resistant genes, and virulence of human S. suis serotype 14.
Genomes of 11 S. suis serotype 14 were sequenced by short- and long-read sequencing platforms. The genomes were analyzed for genetic relationship, virulence-associated genes, and antimicrobial-resistant genes. Antimicrobial susceptibility was conducted and the virulence was tested based on cell assay.
All isolates belonged to clonal complex (CC) 1, with nine sequence type (ST) 105 isolates and each isolate of ST1 and ST237. They were susceptible to penicillin, whereas tetracycline and macrolide were resistance due to tetO and ermB. Genomic analysis revealed that the serotype 14-ST105 isolates were closely related to zoonotic serotype 14-ST105 isolates from Vietnam and the serotype 1-ST105 Thai strain. The serotype 14-ST1 isolate was closely related to pig-diseased serotype 1-ST1 isolates from UK and USA, whereas the serotype 14-ST237 isolate was related to serotype 1-ST237 strains recovered from healthy pig from Thailand. Of 150 virulence-associated genes, 13 were absent from the serotype 14 isolates, including atl1, atlAss, hhly3, nisK, nisR, pnuC, salK, salR, sp1, srtG, virB4, virD4, and zmp. The virulence of strain 32481, a representative S. suis serotype 14-ST105 isolate showed reduced adhesion and invasion of two epithelial cell lines (A549 and HeLa) when compared to the serotype 2-ST1 strain P1/7, whereas apoptosis was similar.
This study highlighted the pathogenic potential of virulent serotype 14-ST105 strains and the need for increased monitoring of S. suis serotypes other than for serotype 2.
猪链球菌14型是东南亚地区第二常见的血清型，在该地区高度流行。本研究旨在对人源猪链球菌14型的遗传背景、种群结构、毒力基因、抗菌耐药基因及毒力进行特征分析。
采用短读长和长读长测序平台对11株猪链球菌14型的基因组进行测序。对基因组进行遗传关系、毒力相关基因和抗菌耐药基因分析。进行抗菌药物敏感性试验，并基于细胞试验检测毒力。
所有分离株均属于克隆复合体（CC）1，其中有9株序列型（ST）105分离株以及各1株ST1和ST237分离株。它们对青霉素敏感，而由于tetO和ermB基因，对四环素和大环内酯类耐药。基因组分析表明，14型-ST105分离株与人源14型-ST105分离株及1型-ST105泰国菌株密切相关。14型-ST1分离株与来自英国和美国的猪病源1型-ST1分离株密切相关，而14型-ST237分离株与从泰国健康猪中分离出的1型-ST237菌株相关。在150个毒力相关基因中，14型分离株缺失13个，包括atl1、atlAss、hhly3、nisK、nisR、pnuC、salK、salR、sp1、srtG、virB4、virD4和zmp。与2型-ST1菌株P1/7相比，猪链球菌14型-ST105代表性分离株32481对两种上皮细胞系（A549和HeLa）的黏附及侵袭能力降低，而诱导凋亡能力相似。
本研究突出了强毒株14型-ST105菌株的致病潜力，以及加强对除2型之外其他猪链球菌血清型监测的必要性。
