Martin T R, Ruzinski J T, Rubens C E, Chi E Y, Wilson C B
Medical Research Service, Veterans Affairs Medical Center, Seattle, WA.
J Infect Dis. 1992 Feb;165(2):306-14. doi: 10.1093/infdis/165.2.306.
To study the importance of the type-specific polysaccharide capsule of group B streptococci (GBS) in the pathogenesis of lung infections, bacterial clearance rates and lung cellular responses to encapsulated and unencapsulated variants of types III and Ia GBS strains were investigated in rats. Bacteria were instilled by direct intratracheal inoculation to simulate aspiration during parturition. Neonates failed to eliminate encapsulated or unencapsulated GBS strains within 6 h of inoculation, whereas adults cleared greater than 90% of each strain within 6 h. Neutrophils accumulated rapidly in the lungs of neonates and adults in response to all GBS strains. Immediately after inoculation, neonatal alveolar macrophages contained fewer encapsulated GBS than did adult alveolar macrophages and fewer encapsulated than unencapsulated GBS, suggesting that the capsule impairs the initial phagocytosis of GBS in the lungs of neonates. Animal age was a more important determinant of bacterial elimination from the lung than the type-specific GBS capsule. However, both age and the bacterial capsule were important determinants of systemic dissemination.
为研究B族链球菌（GBS）的型特异性多糖荚膜在肺部感染发病机制中的重要性，在大鼠中研究了细菌清除率以及肺细胞对III型和Ia型GBS菌株的荚膜型和无荚膜型变体的反应。通过直接气管内接种滴注细菌，以模拟分娩期间的吸入情况。新生大鼠在接种后6小时内无法清除荚膜型或无荚膜型GBS菌株，而成年大鼠在6小时内清除了每种菌株的90%以上。中性粒细胞因所有GBS菌株而在新生大鼠和成年大鼠的肺中迅速积聚。接种后立即观察到，新生大鼠肺泡巨噬细胞所含的荚膜型GBS比成年大鼠肺泡巨噬细胞少，且所含的荚膜型GBS比无荚膜型GBS少，这表明荚膜会损害新生大鼠肺中GBS的初始吞噬作用。与GBS的型特异性荚膜相比，动物年龄是肺部细菌清除的更重要决定因素。然而，年龄和细菌荚膜都是全身播散的重要决定因素。
