Nithyanand Paramasivam, Beema Shafreen Raja Mohmed, Muthamil Subramanian, Karutha Pandian Shunmugiah
School of Chemical & Biotechnology, Centre for Research on Infectious Diseases (CRID), SASTRA University, Tirumalaisamudram, Thanjavur, 613401, Tamil Nadu, India,
Antonie Van Leeuwenhoek. 2015 Jan;107(1):263-72. doi: 10.1007/s10482-014-0324-z. Epub 2014 Nov 4.
Group A Streptococci (GAS) are involved in a number of life threatening diseases and biofilm formation by these pathogens are considered as an important virulence determinant as it mediates antibiotic resistance among them. In the present study, we have explored the ability of (+)-usnic acid, a lichen secondary metabolite, as an antibiofilm agent against four serotypes of Streptococcus pyogenes causing pharyngitis. Usnic acid inhibited the biofilms of M serotypes M56, st38, M89 efficiently and the biofilm of M74 to a lesser extent. Confocal imaging of the treated samples showed that usnic acid reduced the biomass of the biofilms when compared to that of the control. Fourier Transfer Infrared (FT-IR) spectroscopy indicated that usnic acid reduced the cellular components (proteins and fatty acids) of the biofilms. Interestingly, the FT-IR spectrum further revealed that usnic acid probably acted upon the fatty acids of the biofilms as evident from the disappearance of a peak at 2,455-2,100 cm(-1) when compared to the control only in serotypes M56, st38 and M89 but not in M74. The present study shows, for the first time, that usnic acid can act as an effective antibiofilm agent against GAS.
A 组链球菌（GAS）可引发多种危及生命的疾病，这些病原体形成生物膜被认为是一种重要的毒力决定因素，因为它介导了它们之间的抗生素耐药性。在本研究中，我们探索了地衣次生代谢产物（+）-松萝酸作为一种抗生物膜剂对抗四种引起咽炎的化脓性链球菌血清型的能力。松萝酸有效地抑制了 M56、st38、M89 血清型的生物膜，对 M74 血清型生物膜的抑制作用较小。对处理后的样本进行共聚焦成像显示，与对照相比，松萝酸减少了生物膜的生物量。傅里叶变换红外（FT-IR）光谱表明，松萝酸减少了生物膜的细胞成分（蛋白质和脂肪酸）。有趣的是，FT-IR 光谱进一步显示，松萝酸可能作用于生物膜的脂肪酸，这从与对照相比仅在 M56、st38 和 M89 血清型中 2455 - 2100 cm(-1) 处的峰消失而在 M74 血清型中未消失可以明显看出。本研究首次表明，松萝酸可作为一种有效的抗 GAS 生物膜剂。
