Abstract
BackgroundRespiratory virome is an integral part of the human microbiome and its characterization may contribute to a better understanding of the changes that arise in the disease and, consequently, influence the approach and treatment of patients with acute lower respiratory infections.The aim of this study was to evaluate the presence of respiratory viruses in the lower airways of individuals undergoing invasive mechanical ventilation, with and without acute lower respiratory infection (respectively WRI and WORI groups).MethodsWe studied 44 mini-bronchoalveolar lavage samples (collected with a double catheter, Combicath® kit) from patients with mean age in the seventh decade, 20 from WORI group and 24 from WRI group, who were hospitalized for acute respiratory failure in Intensive Care Units of two hospitals in the Lisbon area. Real-time PCR was applied to verify analyse the presence of 15 common respiratory viruses (adenovirus, human bocavirus, influenza virus A and B, repiratory syncytial virus, human parainfluenza virus types 1, 2, 3 and 4, human enterovirus, human rhinovirus, human metapneumovirus, human coronavirus group 1 (229E, NL63) and 2 (OC43, HKU1).ResultsRespiratory viruses were detected in six of the 20 patients in the WORI group: influenza AH3 (n = 2), parainfluenza virus 1/3 (n = 2), human rhinovirus (n = 2), respiratory syncytial virus (n = 1) and human metapneumovirus (n = 1).In the WRI group, respiratory viruses were detected in 12 of the 24 patients: influenza AH3 (n = 3), human rhinovirus (n = 3), respiratory syncytial virus (n = 3), human metapneumovirus (n = 3), human bocavirus (n = 2) and human enterovirus (n = 1). Simultaneous detection of two viruses was recorded in two samples in both groups.ConclusionsThe results of this study suggest the presence of common respiratory viruses in the lower respiratory tract without causing symptomatic infection, even in carefully collected lower samples. This may have important implications on the interpretation of the results on the diagnostic setting.
Highlights
Respiratory virome is an integral part of the human microbiome and its characterization may contribute to a better understanding of the changes that arise in the disease and, influence the approach and treatment of patients with acute lower respiratory infections
The study of the human virome has been neglected in comparison with the bacterial microbiome, namely the heterogeneity of the viral genome that leads to the absence of universal molecular markers, such as 16S ribosomal Ribonucleic acid (RNA) for bacteria or fungal internal transcribed spacer region for fungi, the difficulty in working with small biomass samples, the interference of genetic material from the host, inadequate bioinformatic instruments for its analysis and the absence of robust databases [2, 3]
In order to achieve this, we evaluated the presence of the most common respiratory viruses in the population [15], in lower airway samples collected from individuals with and without respiratory infection, undergoing mechanical ventilation, using real-time Polymerase Chain Reaction and Reverse Transcription-Polymerase Chain Reaction techniques
Summary
Respiratory virome is an integral part of the human microbiome and its characterization may contribute to a better understanding of the changes that arise in the disease and, influence the approach and treatment of patients with acute lower respiratory infections. The lung was considered a sterile organ [4], which was explained by the protective mechanisms of the upper airways and the barrier function of the mucosa of the lower airways. The presence of bacteria in the lower airways was interpreted as a pathological phenomenon, based on cultural microbiological information [5]. It was explained as transient migration by microaspiration, reflecting the composition of the upper respiratory tract, the biomass would be lower. Respiratory culture-based protocols sought only to identify clinically significant pathogens [8]
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