Study on the pathogenesis of normal flora in respiratory tract infection and on the diagnostic methods for the flora

经胸针吸分离出口腔内正常植物群的米勒链球菌群和厌氧菌，可有效防止口腔内正常植物群污染致病菌。这表明S.在小鼠肺炎模型上研究其致病机制发现，混合感染的S. milleri群和厌氧菌死亡率高，肺部存活时间长，病理组织学改变严重。milleri组和厌氧菌组的感染率分别高于单一感染组。这表明S. milleri群和厌氧菌。感染部位分离的milleri群菌株对人白细胞吞噬和吞噬杀伤S. milleri组比正常植物群组更明显。抑菌作用的强弱取决于细菌被膜的存在。以粘多糖为主要成分的荚膜物质的加入也能抑制中性粒细胞对S.米勒里集团荚膜物质的存在可能是S. milleri组菌株。厌氧菌代谢产物短链脂肪酸抑制中性粒细胞对细菌的吞噬和吞噬杀伤功能，但能促进S.从临床微生物学的角度来看，存在的问题是S.米勒里集团阐明了其取决于所用血琼脂平板和鉴定试剂盒的类型。

Streptococcus milleri group and anaerobes, recognized as normal flora in the mouth, were proved to be isolated from the patients of acute pneumonia, lung abscess and thoracic empyema by the methods of transthoracic needle aspiration, which could prevented the causative organisms from contamination with normal flora. This suggested that S. milleri group and anaerobes were important causative organisms in pulmonary infections.Studies on the mechanisms of their pathogenicity in the mice model of pneumonia showed that the higher mortality, longer survival in the lungs and more severe pathohistological changes in the mixed infection of S. milleri group and anaerobes than in the single infection, respectively. This suggested that there may be a synergistic effect between S. milleri group and anaerobes.In vitro studies demonstrated that S. milleri group strains isolated from the infectious lesions had stronger ability to inhibit the function of phagocytosis and phagocytic killing of human leukocytes against S. milleri group than that from normal flora. The degree of the inhibition depended on the presence of capsule of the bacteria. The addition of capsular material, mainly composed of mucopolysaccharide, could also inhibited the neutrophil function of phagocytic killing against S. milleri group. The presence of capsular material might be a pathogenicity of S. milleri group strains. On the other hand, the metabolic substances of anaerobes, short-chain fatty acids, inhibited the neutrophil function of phagocytosis and phagocytic killing against bacteria, while they could promoted the growth of S. milleri group.The problems from the view of clinical microbiology was the isolation and identification of S. milleri group. It was elucidated that it depended on what kind of blood agar plate and identification kit used.