Background. Streptococcus pneumoniae is a major causative bacteria of pneumonia and invasive pneumococcal disease (IPD); however, the mechanisms underlying its severity and invasion remain to be defined. Pneumococcal colonies exhibit opaque and transparent opacity phase variations, which have been associated with invasive infections and nasal colonization, respectively, in animal studies. This study evaluated the relationship between the opacity of pneumococcal colonies and the clinical presentation of pneumococcal pneumonia. Methods. This retrospective study included adult patients hospitalized with pneumococcal pneumonia between 2012 and 2019 at four tertiary medical institutions. Pneumococcal strains from lower respiratory tract specimens were determined for their serotypes and microscopic colony opacity, and the association between the opacity phase and the severity of pneumonia was evaluated. Serotypes 3 and 37 with mucoid colony phenotypes were excluded from the study because their colony morphologies were clearly different. Results. A total of 92 patients were included. Most patients were older adults (median age: 72 years) and males (67 %), and 59 % had community-acquired pneumonia. Of the 92 patients, 41 (45 %), 12 (13 %), and 39 (42 %) patients had opaque, transparent, and mixed variants in their pneumococcal colony, respectively. The opaque and non-opaque pneumococcal variants had no statistically significant difference in patient backgrounds. Although the pneumonia severity index score did not differ between the opaque and non-opaque groups, the rate of bacteremia was significantly higher in the opaque group than in the non-opaque group. Serotype distribution was similar between the groups. Conclusions. Opaque pneumococcal variants may cause pneumonia and invasive diseases in humans. This study could help elucidate IPD, and opacity assessment may serve as a predictor for IPD.

中文翻译：

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住院成人肺炎患者肺炎球菌菌落相变异的相关临床特征

背景。 肺炎链球菌是肺炎和侵袭性肺炎球菌病（IPD）的主要致病菌；然而，其严重性和侵袭性的机制仍有待确定。肺炎球菌菌落表现出不透明和透明不透明相位变化，在动物研究中分别与侵袭性感染和鼻定植相关。本研究评估了肺炎球菌菌落的混浊度与肺炎球菌肺炎的临床表现之间的关系。方法。这项回顾性研究纳入了 2012 年至 2019 年间在四家三级医疗机构住院的肺炎球菌肺炎成年患者。确定下呼吸道标本中的肺炎球菌菌株的血清型和显微镜下菌落混浊度，并评估混浊期与肺炎严重程度之间的关联。具有粘液集落表型的血清型 3 和 37 被排除在研究之外，因为它们的集落形态明显不同。结果。总共包括 92 名患者。大多数患者是老年人（中位年龄：72 岁）和男性（67%），其中 59% 患有社区获得性肺炎。在 92 名患者中，41 名 (45%)、12 名 (13%) 和 39 名 (42%) 患者的肺炎球菌菌落中分别存在不透明、透明和混合变异。不透明和非不透明肺炎球菌变种在患者背景中没有统计学上的显着差异。尽管不透明组和不透明组之间的肺炎严重程度指数评分没有差异，但不透明组的菌血症发生率显着高于不透明组。各组之间的血清型分布相似。结论。不透明肺炎球菌变种可能导致人类肺炎和侵袭性疾病。这项研究可以帮助阐明 IPD，并且不透明度评估可以作为 IPD 的预测指标。