Ouancharee Wajeeorn, Kerdsin Anusak, Van Doan Hien, Chitmanat Chanagun, Faksri Kiatichai, Lulitanond Aroonlug, Chanawong Aroonwadee, Charoensri Nicha
Biomedical Sciences, Graduate School, Khon Kaen University, Khon Kaen, Thailand.
Centre for Research and Development of Medical Diagnostic Laboratories (CMDL), Faculty of Associated Medical Sciences, Khon Kaen University, Khon Kaen, Thailand.
J Med Microbiol. 2025 Mar;74(3). doi: 10.1099/jmm.0.001970.
. Group B (GBS) is a multi-host pathogen causing pneumonia and meningitis in humans as well as streptococcal diseases in tilapia and mastitis in cattle. Thailand has experienced a significant increase in GBS infections that greatly impact health and economics.. The antimicrobial resistance (AMR) and genotype data of GBS in Thailand are still limited and require further study.. This study aimed to describe AMR profiles and molecular characteristics, especially antimicrobial resistance genes (ARGs) and virulence factor (VF) genes of GBS in Thailand.. AMR profiles of 221 GBS isolates from humans, fish and freshwater were examined. Whole-genome sequencing of 41 representative isolates was used to investigate capsular genotypes and sequence types (STs), ARGs and VF genotypes.. All GBS isolates were susceptible to penicillin; the majority (99.1%) showed resistance to tetracycline. In addition, the rates of resistance to clindamycin, erythromycin and levofloxacin were 22.6%, 20.4% and 2.3%, respectively; multidrug-resistant (MDR) isolates (TE-E-CM and TE-E-CM-LVX) were 19.5%. Among 41 representative isolates, the dominant types were capsular genotype III (63.4%) and ST283 (43.9%). ARGs associated with resistance to tetracycline (, and ), erythromycin (, , and ) and clindamycin (, and ) were identified. Additionally, point mutations responsible for levofloxacin resistance, S81L in GyrA, S79F/Y in ParC and H221Y in ParE, were found. The MDR isolates belonged to various STs, predominantly clustering in capsular types III (60.0%) and Ib (30.0%). The MDR-hypervirulent ST17 and ST19 harboured multiple ARGs and mutations affecting quinolone resistance. Different VF gene patterns were found among hypervirulent STs (ST12, ST17, ST19 and ST283). Notably, a unique nt deletion [c.(1013_1020)delG] in was found only in ST283.. This study elucidated significant antimicrobial characteristics of a substantial number of GBS in Thailand. Moreover, the distribution of the hypervirulent ST283 and the genotypes of MDR-hypervirulent GBS were first described.
B组链球菌（GBS）是一种多宿主病原体，可导致人类肺炎和脑膜炎，以及罗非鱼的链球菌病和牛的乳腺炎。泰国GBS感染显著增加，对健康和经济产生了重大影响。泰国GBS的抗菌药物耐药性（AMR）和基因型数据仍然有限，需要进一步研究。本研究旨在描述泰国GBS的AMR谱和分子特征，特别是抗菌药物耐药基因（ARGs）和毒力因子（VF）基因。检测了来自人类、鱼类和淡水的221株GBS分离株的AMR谱。对41株代表性分离株进行全基因组测序，以研究荚膜基因型和序列类型（STs）、ARGs和VF基因型。所有GBS分离株对青霉素敏感；大多数（99.1%）对四环素耐药。此外，对克林霉素、红霉素和左氧氟沙星的耐药率分别为22.6%、20.4%和2.3%；多重耐药（MDR）分离株（TE-E-CM和TE-E-CM-LVX）为19.5%。在41株代表性分离株中，主要类型为荚膜基因型III（63.4%）和ST283（43.9%）。鉴定出与四环素耐药相关的ARGs（、和）、红霉素耐药相关的ARGs（、、和）和克林霉素耐药相关的ARGs（、和）。此外，还发现了导致左氧氟沙星耐药的点突变，即GyrA中的S81L、ParC中的S79F/Y和ParE中的H221Y。MDR分离株属于各种STs，主要聚集在荚膜类型III（60.0%）和Ib（30.0%）中。MDR-高毒力的ST17和ST19携带多个ARGs和影响喹诺酮耐药性的突变。在高毒力STs（ST12、ST17、ST19和ST283）中发现了不同的VF基因模式。值得注意的是，仅在ST283中发现了中的一个独特核苷酸缺失[c.（1013_1020）delG]。本研究阐明了泰国大量GBS的重要抗菌特征。此外，首次描述了高毒力ST283的分布以及MDR-高毒力GBS的基因型。
