Analysis of serotype distribution and characteristics of nonhemolytic and nonpigmented strains among group B Streptococcus isolates in a southern Taiwan local hospital.

IF 3.7 3区 医学 Q2 INFECTIOUS DISEASES
Hui-Fang Cheng, Zhe-Yu Kuo, Ching-Chiang Lin, Ho-Feng Chen, Horng-Ren Lo, Huey-Wen Shyu, Yi-Fen Wang
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引用次数: 0

Abstract

Purpose: Group B streptococci (GBS) are Gram-positive bacteria that are a leading cause of neonatal infections. Most invasive isolates are β-hemolytic, and hemolytic activity is critical for GBS virulence. Although nonhemolytic GBS strains are occasionally isolated, they are often thought to be attenuated in virulence. Recent studies have observed that many nonhemolytic and nonpigmented (NH/NP) strains originated from invasive infections, including bacteremia and meningitis, in neonates or adults. The mutations causing the NH/NP phenotype are predominantly localized in the cyl operon and abx1 gene. Previous studies on group B streptococci in Taiwan have focused on the serotype and genotype distribution. In this study, we investigated the serotype distribution of the NH/NP strains and detected the mutations of abx1.

Methods: One hundred clinical GBS strains from non-invasive (vaginal and rectal swabs, 69) and invasive infections (blood, urine and abscess, 31), including 10 NH/NP isolates, were collected during 2019-2021 at Fooyin University Hospital. To confirm GBS isolates, we have developed a multiplex PCR method that detects GBS isolates, virulent strain ST-17 and virulent factor Srr1 simultaneously. Molecular serotyping was performed by multiplex PCR assay using serotype specific primer sets. The genomic region containing abx1 was amplified from DNA extracts by PCR and the amplicons were directly sequenced and analyzed on an ABI prism 3730 DNA analyzer.

Results: The capsular serotypes III and VI were the most abundant in both the non-invasive specimens and invasive specimens. The ST-17 isolates were more frequently associated with invasive infections (16.1%, 5/31) than non-invasive diseases or colonization (7.2%, 5/69). The association of NH/NP strains between noninvasive diseases or colonization (10.1, 7/69) and invasive infection (9.7%, 3/31) is nearly compatible. The NH/NP strains were isolated from various serotypes (Ia, III, V and VI) and five NH/NP isolates were serotype III. The virulence factor Srr1was detected in most of the NH/NP isolates (8/10) and one NH/NP isolate was ST-17. Abx1 mutations, including transitions, transversions and deletions, were observed in some NH/NP isolates, but some mutations also observed in hemolytic isolates. Five NH/NP isolates were erythromycin and clindamycin resistant.

Conclusion: These results indicate NH/NP GBS strains may have the potential for invasive infections and may show higher tendency to get mutated.

台湾南部一家地方医院 B 群链球菌分离菌株血清型分布及非溶血性和非色素性菌株特征分析。
目的:乙型链球菌(GBS)是革兰氏阳性细菌,是新生儿感染的主要病因。大多数侵袭性分离株都有β-溶血性,而溶血活性对 GBS 的毒力至关重要。虽然偶尔也会分离到非溶血性 GBS 菌株,但通常认为它们的毒力较弱。最近的研究发现,许多非溶血性和非色素性(NH/NP)菌株起源于新生儿或成人的侵袭性感染,包括菌血症和脑膜炎。导致 NH/NP 表型的突变主要位于 cyl 操作子和 abx1 基因中。以往对台湾 B 群链球菌的研究主要集中在血清型和基因型的分布上。本研究调查了 NH/NP 菌株的血清型分布,并检测了 abx1 基因的突变:方法:2019-2021年期间,我们在福银大学医院收集了100株临床GBS菌株,分别来自非侵袭性感染(阴道和直肠拭子,69株)和侵袭性感染(血液、尿液和脓肿,31株),其中包括10株NH/NP分离株。为确认 GBS 分离株,我们开发了一种多重 PCR 方法,可同时检测 GBS 分离株、毒株 ST-17 和致病因子 Srr1。使用血清型特异性引物组进行多重 PCR 分析,进行分子血清型鉴定。通过 PCR 从 DNA 提取物中扩增含有 abx1 的基因组区域,并直接对扩增子进行测序,然后在 ABI prism 3730 DNA 分析仪上进行分析:结果:在非侵袭性标本和侵袭性标本中,胶囊血清型 III 型和 VI 型最多。与非侵袭性疾病或定植(7.2%,5/69)相比,ST-17分离株更常与侵袭性感染相关(16.1%,5/31)。NH/NP菌株与非侵袭性疾病或定植(10.1%,7/69)和侵袭性感染(9.7%,3/31)的关联几乎一致。NH/NP 菌株分离自不同血清型(Ia、III、V 和 VI),其中 5 株 NH/NP 菌株分离自 III 血清型。大多数 NH/NP 分离物(8/10)中检测到毒力因子 Srr1,一个 NH/NP 分离物为 ST-17。在一些 NH/NP 分离物中观察到 Abx1 突变,包括转换、反转和缺失,但在溶血分离物中也观察到一些突变。五个 NH/NP 分离物对红霉素和克林霉素耐药:这些结果表明,NH/NP GBS 菌株可能具有侵袭性感染的潜能,并有较高的变异倾向。
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来源期刊
CiteScore
10.40
自引率
2.20%
发文量
138
审稿时长
1 months
期刊介绍: EJCMID is an interdisciplinary journal devoted to the publication of communications on infectious diseases of bacterial, viral and parasitic origin.
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