Dunn D L, Barke R A, Ewald D C, Simmons R L
Infect Immun. 1985 May;48(2):287-91. doi: 10.1128/iai.48.2.287-291.1985.
Escherichia coli and Bacteroides fragilis are common copathogens in clinical intra-abdominal sepsis, yet it is unclear how they interact synergistically in vivo. We sought to determine whether E. coli and B. fragilis, in combination but not alone, could exert a detrimental effect on the peritoneal host defenses of translymphatic absorption and bacterial phagocytosis. Our data indicated that nonviable E. coli (O18ab:K56/K7:- and O111:B4), Klebsiella pneumoniae, B. fragilis, and Bacteroides thetaiotaomicron were handled in a similar fashion by both host defenses of the peritoneal cavity. The use of 2 X 10(8) nonviable radiolabeled E. coli as a tracer and either 2 X 10(9) B. fragilis or 2 X 10(9) E. coli (either viable or nonviable) as a competing agent to inhibit host defenses demonstrated that although clearance and phagocytosis could be inhibited, the inhibition occurred to a similar degree with either E. coli or B. fragilis. Thus, B. fragilis did not compete to any greater extent than E. coli did for peritoneal clearance or opsonization and phagocytosis in vivo. These data indicate that bacterial synergy probably does not occur on the basis of reduced peritoneal clearance or by a reduction in the opsonization and phagocytosis of either organism by the copathogen. These results provide indirect support for the hypothesis that in bacterial synergy, one organism directly stimulates the growth of the other, perhaps by providing a growth factor.
大肠杆菌和脆弱拟杆菌是临床腹腔内脓毒症常见的共同病原体,但它们在体内如何协同作用尚不清楚。我们试图确定大肠杆菌和脆弱拟杆菌联合而非单独作用时,是否会对经淋巴吸收和细菌吞噬的腹膜宿主防御产生有害影响。我们的数据表明,腹腔的两种宿主防御机制对无活力的大肠杆菌(O18ab:K56/K7:-和O111:B4)、肺炎克雷伯菌、脆弱拟杆菌和嗜内脏拟杆菌的处理方式相似。使用2×10⁸个无活力的放射性标记大肠杆菌作为示踪剂,以及2×10⁹个脆弱拟杆菌或2×10⁹个大肠杆菌(有活力或无活力)作为竞争剂来抑制宿主防御,结果表明,虽然清除和吞噬作用可被抑制,但大肠杆菌和脆弱拟杆菌的抑制程度相似。因此,在体内,脆弱拟杆菌在腹膜清除或调理吞噬作用方面的竞争程度并不比大肠杆菌更大。这些数据表明,细菌协同作用可能不是基于腹膜清除减少或共同病原体对任一病原体的调理吞噬作用降低而发生的。这些结果为以下假设提供了间接支持:在细菌协同作用中,一种生物体可能通过提供生长因子直接刺激另一种生物体的生长。