Microbiota of the lower respiratory tract in community-acquired pneumonia, including cases associated with SARS-CoV-2

Abstract

Introduction. Many aspects of the pathogenesis and pathomorphology of pneumonia associated with novel coronavirus require a comprehensive study using modern diagnostic methods. The aim of the study was to study the microbiota of the lower respiratory tract in community-acquired pneumonia associated with SARS-CoV-2, to assess the antibiotic and phage resistance of circulating strains of microorganisms. Materials and methods. The analysis of biosamples from 486 patients undergoing inpatient treatment in five mono-hospitals in Tyumen and Tyumen region with a diagnosis of moderate and severe community-acquired pneumonia was carried out. In almost 90% of cases patients received oxygen therapy, about 8% of patients were connected to ventilators. The inoculation of the cultures with clinical samples was carried out for six months (from April to October 2020). The isolated bacterial strains were identified by mass spectrometry. The resistance to antimicrobial drugs and bacteriophages was assessed for identified isolated. Results. Gram-positive cocci, mainly opportunistic microorganisms of the genus Streptococcus and Candida fungi predominated in the microbiota of the lower respiratory tract of patients diagnosed with community-acquired pneumonia associated with SARS-CoV-2. At the same time, bacteria of the Enterobacteriaceae family and nonfermenting gram-negative bacteria were less common compared to patients without coronavirus infection. In the structure of pathogens, the leading position was occupied by the bacteria K. pneumoniae and Acinetobacter spp. The analysis of the sensitivity of microorganisms to antimicrobial drugs showed the highest resistance rates in strains of Acinetobacter spp., Enterococcus spp., Coagulase-negative Staphylococcus. It has been established that in the group of patients with community-acquired pneumonia associated with SARS-CoV-2, the risk of infection with Streptococcus spp. with high level of antibiotic resistance was 1.5 times higher, and taking into account the 95% confidence interval, the value of this indicator ranged from 1.1 to 2.1 times. Conclusion. The data obtained indicate that the microbiota of the lower respiratory tract in community-acquired pneumonia associated with SARS-CoV-2 is represented mainly by bacteria of the genus Streptococcus, which have a high level of resistance to antimicrobial drugs.