Background When severe, COVID-19 shares many clinical features with bacterial sepsis. Yet, secondary bacterial infection is uncommon. However, as epithelium is injured and barrier function is lost, bacterial products entering the circulation might contribute to the pathophysiology of COVID-19. Methods We studied 19 adults, severely ill patients with COVID-19 infection, who were admitted to King Chulalongkorn Memorial Hospital, Bangkok, Thailand, between 13th March and 17th April 2020. Blood samples on days 1, 3, and 7 of enrollment were analyzed for endotoxin activity assay (EAA), (1 → 3)-β- d -glucan (BG), and 16S rRNA gene sequencing to determine the circulating bacteriome. Results Of the 19 patients, 13 were in intensive care and 10 patients received mechanical ventilation. We found 8 patients with high EAA (≥ 0.6) and about half of the patients had high serum BG levels which tended to be higher in later in the illness. Although only 1 patient had a positive blood culture, 18 of 19 patients were positive for 16S rRNA gene amplification. Proteobacteria was the most abundant phylum. The diversity of bacterial genera was decreased overtime. Conclusions Bacterial DNA and toxins were discovered in virtually all severely ill COVID-19 pneumonia patients. This raises a previously unrecognized concern for significant contribution of bacterial products in the pathogenesis of this disease.

中文翻译：

---

重症 COVID-19 患者的内毒素血症和循环细菌组

背景 当严重时，COVID-19 与细菌性败血症有许多共同的临床特征。然而，继发细菌感染并不常见。然而，由于上皮受损且屏障功能丧失，进入循环系统的细菌产物可能会导致 COVID-19 的病理生理学。方法 我们研究了 2020 年 3 月 13 日至 4 月 17 日期间入住泰国曼谷朱拉隆功国王纪念医院的 19 名患有 COVID-19 感染的成人重症患者。对入组第 1、3 和 7 天的血液样本进行了分析用于内毒素活性测定 (EAA)、(1 → 3)-β-d-葡聚糖 (BG) 和 16S rRNA 基因测序以确定循环细菌组。结果 19例患者中，13例接受重症监护，10例接受机械通气。我们发现 8 名患者 EAA 高（≥ 0.6），约一半患者血清 BG 水平高，且在疾病后期往往更高。虽然只有 1 名患者血培养呈阳性，但 19 名患者中有 18 名 16S rRNA 基因扩增呈阳性。变形菌门是最丰富的门。细菌属的多样性随着时间的推移而减少。结论 在几乎所有重症 COVID-19 肺炎患者中都发现了细菌 DNA 和毒素。这引起了人们以前未被认识到细菌产物在这种疾病的发病机制中的重要作用。