Virulence of Entamoeba histolytica trophozoites. Effects of bacteria, microaerobic conditions, and metronidazole.
Virulence of Entamoeba histolytica trophozoites. Effects of bacteria, microaerobic conditions, and metronidazole.
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DOI：
10.1084/jem.160.2.353
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发表时间：
1984-08-01
影响因子：
15.3
通讯作者：
Mirelman, D
中科院分区：
文献类型：
--
作者：
Bracha, R;Mirelman, D
溶组织内阿米巴HK-9或HM-1：IMSS菌株的无菌生长的滋养体与各种类型的革兰氏阴性菌在相对短的时间内的结合显著增加了它们的毒力，正如它们破坏组织培养细胞单层的能力所证明的那样。滋养体与热灭活、戊二醛固定或超声破坏的细菌或用蛋白质合成抑制剂处理的细菌的相互作用并不增加阿米巴的毒力。然而，经过致死性辐照的细菌保留了它们的刺激特性，并且摄入细菌的滋养体受到保护，免受添加的过氧化氢的毒性影响。在微好氧条件下（5%O2，10%CO2）进行的实验中也发现了阿米巴的毒性增加。由于与细菌相关而引起的阿米巴毒力增强被甲硝唑特异性阻断，但四环素或氨基糖苷类不能阻断，并且刺激滋养体的甲硝唑摄取率高出2至3倍。结果表明，无菌生长的E.溶组织滋养体可能在相当大的程度上取决于细胞的还原能力。微好氧条件和与细菌的结合明显地刺激了阿米巴的电子传递系统。细菌可以通过酶系统、组分或产物的贡献作为氧化分子和代谢物的广泛清除剂。
The association of axenically grown trophozoites of Entamoeba histolytica strains HK-9 or HM-1:IMSS with various types of gram- negative bacteria for relatively short periods markedly increased their virulence, as evidenced by their ability to destroy monolayers of tissue-cultured cells. Interaction of trophozoites with bacteria that were heat inactivated, glutaraldehyde fixed, or disrupted by sonication, or bacteria treated with inhibitors of protein synthesis, did not augment amebic virulence. Lethally irradiated bacteria, however, retained their stimulative properties and trophozoites that ingested bacteria were protected from the toxic effects of added hydrogen peroxide. An increase in virulent properties of amebae was also found in experiments carried out under microaerobic conditions (5% O2, 10% CO2). The augmentation of amebic virulence due to association with bacteria was specifically blocked by metronidazole, but not by tetracycline or aminoglycosides, and the rate of metronidazole uptake in stimulated trophozoites was two to three times higher. The results obtained suggest that virulence of axenically grown E. histolytica trophozoites may depend to a considerable extent on the cell's reducing power. Both microaerobic conditions and the association with bacteria apparently stimulate the electron transport system of the ameba. Bacteria may function as broad range scavengers for oxidized molecules and metabolites through the contribution of enzymatic systems, components, or products.