糖尿病マウスにおけるEscherichia coli実験尿路感染症 : 尿路定着性と白血球機能について

Abstract

病原性因子としての線毛の種類およびhemolysin産生能の異なるEscherichia coli 6株を用い, 正常ならびにstreptozotocin誘発糖尿病マウスでの感染性と白血球機能について検討した.1)線毛保有株は多核白血球による貪食を受けやすかったが, 殺菌されやすさとは相関せず, マンノース感受性(MS+)ならびに非感受性MR+血球凝集をともに示すMS+・MR+株では好中球による殺菌に抵抗性を示した.2) OEC-709, OEC-716, ならびにOEC-734は, 血清による殺菌に対して抵抗性を示したが, この3株に対する糖尿病マウス好中球の殺菌能は正常マウスに比し有意に低下していた.3)正常マウスでの膀胱ならびに腎内生菌数は, MS+・MR+株で最も高く, MS-・MR-株で最も低かった.4)糖尿病マウスでの膀胱ならびに腎内生菌数は, MS-・MR-の1株を除き, 正常マウスに比し高く, 特にその殺菌に好中球の関与が大きい株(OEC-709, 716, 734)において有意差を認めた

Relationship between polymorphonuclear leukocyte (PMN) function and susceptibility to infections in diabetic mice was studied. In the experimental urinary tract infections, 6 strains of Escherichia coli with different fimbrial expression and hemolysin production were used. In contrast with non-fimbriated strains, fimbriated strains were more susceptible to phagocytosis by PMN. MS+.MR+ strains, however, showed resistance to intracellular killing by PMN. OEC-709, OEC-716 (MS+.MR+ strains), and OEC-734 (MS+.MR- strains), also showed resistance to the bactericidal activity of the serum. The killing activities of PMN derived from diabetic mice against these 3 strains were significantly lower than those of PMN from normal mice. In normal mice, MS+.MR+ strains showed the strongest colonization ability to the bladder and kidney, whereas MS-.MR- strains showed the weakest ability among the strains. In diabetic mice, the number of bacteria colonizing to the bladder and kidney was higher than that in normal mice, except for one MS-.MR- strain. Significant differences were observed in the strains (OEC-709, 716, 734), in which PMN was concerned strongly in the bacterial killing. Finally, these findings suggest that deterioration of the bactericidal activity of PMN in a diabetic state is involved in increased susceptibility of diabetic mice.