Introduction: Acute respiratory viral infections (ARVI) are one of the most pressing medical and social problems of modern society and the main cause of morbidity in children, especially at the age of 3 to 7 years. This is due to the visits to organized children’s groups and close contact with the infected, instability of post-infectious immunity, lack of personal hygiene skills and reinfection.

Aim: The aim of our study was to identify the etiological structure of ARVI in preschool children.

Materials and methods: The study was conducted in 2019 on the basis of the “City Children’s Clinical Hospital of St. Zinaida” of Sumy City Council. In accordance with this goal, 98 preschool children with ARVI were examined. To establish the etiological structure of ARVI, a study of nasopharyngeal lavage was performed on the basis of the virological laboratory of the State Institution “Sumy Regional Laboratory Center”. Species identification of respiratory viruses was performed by polymerase chain reaction using the test system “Ampli Sense SARS-screen”. The study of microflora was conducted on the basis of the microbiological laboratory of Sumy State University using classical methods of isolation and identification. 

Results: The dominant etiological agents in children were rhinoviruses (28,6%), adenoviruses (24,3%) and influenza B virus (14,3%). In the studied material, we identified relatively rare on that time metapneumoviruses and coronaviruses. Two different respiratory viruses were isolated in 15,9%. Combinations of viruses were different, but most often isolated respiratory syncytial virus. A total of 168 strains of microorganisms were isolated and identified from children. Microbes were excreted from the pharynx more often than from the nose (in 75,0±1,3% and 39,3±3,5%, respectively) (p≤0,001) of the patients. The frequency of excretion of microbes in monoculture from the nose was higher than from the throat (p≤0,001), two-component associations were more often on the mucous of the pharynx than the nose (p≤0,01). From the nose and throat of children together with representatives of indigenous microflora in 52,3% of children were isolated opportunistic pathogens. Among them, the dominant positions belonged to staphylococci (35,7%) and streptococci (29,2%). In the majority of patients (82,2%) the concomitant bacterial microflora was not isolated when the viral nature of ARVI was confirmed. 

Conclusions. Thus, these results indicate that in children with acute respiratory viral infections, the mucous membrane of the nasal cavity is colonized by microbes much less frequently and in smaller quantities compared to the mucous of the throat. More than 80% of children had ARVI without the addition of bacterial microflora.