Acidic pH Strongly Enhances In Vitro Biofilm Formation by a Subset of Hypervirulent ST-17 Streptococcus agalactiae Strains
Acidic pH Strongly Enhances In Vitro Biofilm Formation by a Subset of Hypervirulent ST-17 Streptococcus agalactiae Strains
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DOI：
10.1128/aem.03627-13
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发表时间：
2014-04-01
影响因子：
4.4
通讯作者：
Maione, Domenico
中科院分区：
文献类型：
--
作者：
D'Urzo, Nunzia;Martinelli, Manuele;Maione, Domenico
无乳链球菌，又称B组链球菌(GBS)，是高达40%的健康女性肛门生殖道粘膜的主要定殖者，是全球侵袭性新生儿感染的重要原因。在已知的10种包膜血清型中，GBS III型占新生儿脑膜炎病例的30%至76%。近年来，GBS形成生物膜的能力引起了人们的关注，因为它可能在适应和毒力方面发挥作用。在这里，开发了一种新的体外生物膜形成方案，以保证更严格的条件，更好地区分强生物膜形成菌株、低生物膜形成菌株和非生物膜形成菌株，并便于数据解释。用该方法筛选了366株GBS临床分离株的生物被膜形成能力，这些分离株来自孕妇和不同血清型的新生儿感染，与培养基成分和pH有关。结果鉴定了血清型III和V型的一部分分离株在酸性条件下形成了强大的生物膜。重要的是，最好的生物膜形成物属于血清III型超强毒力克隆ST-17。此外，蛋白酶K强烈抑制生物膜的形成和分解成熟的生物膜的能力表明，蛋白质在促进GBS生物膜的启动和促进生物膜结构稳定方面起着至关重要的作用。
Streptococcus agalactiae, also known as group B Streptococcus (GBS), is a primary colonizer of the anogenital mucosa of up to 40% of healthy women and an important cause of invasive neonatal infections worldwide. Among the 10 known capsular serotypes, GBS type III accounts for 30 to 76% of the cases of neonatal meningitis. In recent years, the ability of GBS to form biofilm attracted attention for its possible role in fitness and virulence. Here, a new in vitro biofilm formation protocol was developed to guarantee more stringent conditions, to better discriminate between strong-, low-, and non-biofilm-forming strains, and to facilitate interpretation of data. This protocol was used to screen the biofilm-forming abilities of 366 GBS clinical isolates from pregnant women and from neonatal infections of different serotypes in relation to medium composition and pH. The results identified a subset of isolates of serotypes III and V that formed strong biofilms under acidic conditions. Importantly, the best biofilm formers belonged to serotype III hypervirulent clone ST-17. Moreover, the abilities of proteinase K to strongly inhibit biofilm formation and to disaggregate mature biofilms suggested that proteins play an essential role in promoting GBS biofilm initiation and contribute to biofilm structural stability.