Molecular Virology Unit, Microbiology and Virology Department, Fondazione IRCCS Policlinico San Matteo, 27100 Pavia, Italy.
Department of Biomedical Sciences for Health, University of Milan, 20133 Milan, Italy.
Int J Mol Sci. 2019 May 30;20(11):2664. doi: 10.3390/ijms20112664.
This study aimed at assessing the frequency and the distribution of influenza virus types/subtypes in 172 laboratory-confirmed influenza-positive patients admitted to intensive care units (ICUs) during the 2017-2018 season in the Lombardy region (Northern Italy), and to investigate the presence of molecular pathogenicity markers. A total of 102/172 (59.3%) patients had influenza A infections (83 A/H1N1pdm09, 2 H3N2 and 17 were untyped), while the remaining 70/172 (40.7%) patients had influenza B infections. The 222G/N mutation in the hemagglutinin gene was identified in 33.3% (3/9) of A/H1N1pdm09 strains detected in the lower respiratory tract (LRT) samples and was also associated with more severe infections, whereas no peculiar mutations were observed for influenza B strains. A single-point evolution was observed in site 222 of A/H1N1pdm09 viruses, which might advantage viral evolution by favouring virus binding and replication in the lungs. Data from 17 paired upper respiratory tract (URT) and LRT samples showed that viral load in LRT samples was mostly higher than that detected in URT samples. Of note, influenza viruses were undetectable in 35% of paired URT samples. In conclusion, LRT samples appear to provide more accurate clinical information than URT samples, thus ensuring correct diagnosis and appropriate treatment of patients with severe respiratory infections requiring ICU admission.
本研究旨在评估 2017-2018 年意大利伦巴第地区（北部） 172 例重症监护病房（ICU）确诊流感阳性患者中流感病毒的类型/亚型的频率和分布，并调查分子致病性标志物的存在。总共 172 例患者中有 102 例（59.3%）为甲型流感感染（83 例为 A/H1N1pdm09，2 例为 H3N2，17 例未分型），其余 70 例（40.7%）为乙型流感感染。在呼吸道下部分泌物（LRT）样本中检测到的 9 株 A/H1N1pdm09 株中，有 3 株（3/9）存在血凝素基因 222G/N 突变，该突变与更严重的感染相关，而乙型流感株未观察到特殊突变。在 A/H1N1pdm09 病毒的 222 位单点进化，可能有利于病毒在肺部的结合和复制，从而有利于病毒的进化。17 对上呼吸道（URT）和下呼吸道（LRT）样本的数据显示，LRT 样本中的病毒载量大多高于 URT 样本。值得注意的是，在 35%的配对 URT 样本中未检测到流感病毒。总之，LRT 样本似乎比 URT 样本提供更准确的临床信息，从而确保对需要入住 ICU 的严重呼吸道感染患者进行正确诊断和适当治疗。
