Haque M A, Kohashi O
Department of Microbiology, Saga Medical School, Japan.
Microbios. 1996;86(349):213-23.
Recent work has indicated that the pathogenicity of enteroaggregative Escherichia coli (EAggEC) is strictly regulated by environmental conditions. The growth conditions, susceptibility to the bactericidal activity of serum, and polymorphonuclear leucocytes (PMN) using strains of EAggEC grown in two different culture conditions were examined. Strains of EAggEC grown in casamino acids-yeast extract (CYE) broth at 37 degrees C for 20 h showed resistance to killing by human serum (86.8 +/- 6.9% survival by 2 h) and PMN (67 +/- 5.1% survival by 2 h). In contrast, these strains grown in nutrient broth (NB) showed sensitivity to serum (98.9 +/- 0.5% killing by 2 h) and PMN (98.9 +/- 0.5% killing by 2 h). EAggEC strains cultured in NB became resistant to killing by serum when mixed with extracellular material extracted from the bacteria grown in CYE broth. These results indicate that the growth condition may modulate the sensitivity of EAggEC, and the promotion of extracellular material formation in CYE broth is responsible for the resistance to killing by serum and PMN.
近期研究表明，肠聚集性大肠杆菌（EAggEC）的致病性受到环境条件的严格调控。我们检测了在两种不同培养条件下生长的EAggEC菌株的生长条件、对血清杀菌活性的敏感性以及多形核白细胞（PMN）的作用。在37摄氏度下于酪蛋白氨基酸 - 酵母提取物（CYE）肉汤中培养20小时的EAggEC菌株对人血清杀伤具有抗性（2小时后存活率为86.8±6.9%），对PMN也具有抗性（2小时后存活率为67±5.1%）。相比之下，在营养肉汤（NB）中生长的这些菌株对血清敏感（2小时后杀伤率为98.9±0.5%），对PMN也敏感（2小时后杀伤率为98.9±0.5%）。当在NB中培养的EAggEC菌株与从在CYE肉汤中生长的细菌提取的细胞外物质混合时，它们对血清杀伤产生抗性。这些结果表明，生长条件可能调节EAggEC的敏感性，并且CYE肉汤中细胞外物质形成的促进作用导致了对血清和PMN杀伤的抗性。
