脓肿分枝杆菌细胞壁通透性的研究

Investigation of the membrane permeability of Mycobacterium abscessus

目的了解脓肿分枝杆菌的细胞壁的通透性。方法在含RFP的液体培养基中加入Tween 80以增加细菌细胞壁的通透性,观察对RFP具不同MIC的脓肿分枝杆菌的生长在450 nm的光吸收值(OD450)的变化,同时用电镜对脓肿分枝杆菌标准株、临床耐药株和敏感株的细胞壁进行超微结构的观察。结果临床耐药菌株在同时含1/5MIC浓度的RFP和0.05%Tween 80的液体培养基中生长的OD450值与单含RFP的OD450值比较有显著性差异(P<0.05);临床敏感株和结核杆菌耐药株在两种培养基中的OD450值比较无显著性差异;在电镜下观察,脓肿分枝杆菌耐药株的细胞壁可见有薄层深染线,而敏感株的细胞壁结构均匀。结论脓肿分枝杆菌确实存在细胞壁的低通透性,且脓肿分枝杆菌耐药株和敏感株的细胞壁在结构上有一定差异,因此膜通透性低下可能是其耐RFP的重要原因。

Objective To study the membrane permeability of Mycobacterium abscessus. Methods 0.05 % Tween-80 was added to the liquid culture which contains RFP of 1/5 MIC concentration to increase the cell mem- brane permeability. The growth of Mycobacterium abscessus strains that had different MIC to RFP were evaluated by measuring the optical density （OD） of the growing culture at 450 nm. The ultrastucture of cell wall was oberseved by electron microscopy. Results OD450 of Mycobacterium abscessus clinical drug-resistant strains in the culture that contained both RFP and Tween-80 was significantly smaller than that in the culture contain RFP only （P 〈 0.05）. While for clinical drug-sensitive strain and Mycobacterium tuberculosis drug-resistant strain, there is no significant difference between the OD450 in this two kinds of culture. There seem to be a thin layer of deepdyed structure in the cell wall of resistant strains, while the cell wall was more homogeneous in susceptible strain. Conclusions Mycobacterium abscessus has lower cell membrane permeability. These results can partly explain the reason of Mycobacterium abscessus resistant to RFP.