Saito M, Kajiwara H, Ishikawa T, Iida K I, Endoh M, Hara T, Yoshida S I
Department of Bacteriology, Faculty of Medical Sciences, Kyushu University, Fukuoka, Japan.
Microbiol Immunol. 2001;45(11):777-86. doi: 10.1111/j.1348-0421.2001.tb01314.x.
Streptococcus pyogenes causes severe invasive diseases in humans, including necrotizing fasciitis, sepsis, and streptococcal toxic shock syndrome (STSS). We found that mice infected intramuscularly (i.m.) with S. pyogenes strains developed bacteremia and subsequent sudden death after at least 10 days of a convalescent period. Mostly, it occurred more than 21 days after muscle infection. We provisionally designate this phenomenon as "delayed death." Just after muscle infection, all the mice lost weight and activity, but recovered completely within 3 days. They had kept good activity and a fine coat of fur till one or two days before their death. Some of the dead mice were found to have soft-tissue necrosis. There was no correlation between the virulence leading to the delayed death and the severity of diseases from which strains were isolated. It was also found that the production of neither streptococcal pyrogenic exotoxin (SPE) A nor B correlated to the virulence leading to delayed death. The bacteria obtained from the organs of the mice with delayed death expressed capsule. We suggest that the mice with delayed onset of systemic bacterial dissemination and subsequent death after muscle infection with S. pyogenes are the animal models of STSS, because the pathophysiology is extremely similar to that of human STSS.
化脓性链球菌可导致人类严重的侵袭性疾病，包括坏死性筋膜炎、败血症和链球菌中毒性休克综合征（STSS）。我们发现，肌肉注射（i.m.）化脓性链球菌菌株的小鼠在至少10天的恢复期后会发生菌血症并随后突然死亡。大多数情况下，这种情况发生在肌肉感染后21天以上。我们暂时将这种现象称为“延迟死亡”。在肌肉感染后，所有小鼠体重减轻、活动减少，但在3天内完全恢复。它们在死亡前一到两天一直保持良好的活动状态和光滑的皮毛。一些死亡小鼠被发现有软组织坏死。导致延迟死亡的毒力与分离菌株所引起疾病的严重程度之间没有相关性。还发现，化脓性链球菌致热外毒素（SPE）A和B的产生均与导致延迟死亡的毒力无关。从延迟死亡小鼠器官中分离出的细菌表达荚膜。我们认为，肌肉感染化脓性链球菌后出现全身细菌播散延迟并随后死亡的小鼠是STSS的动物模型，因为其病理生理学与人类STSS极为相似。
