AbstractBackgroundThe investigation is devoted to possible antibiotic resistance formation and its adverse event prognostic influence among young patients with community-acquired pneumonia (CAP) with cytomegalovirus (CMV) persistence and absence of other comorbid pathology.Subjects and methodsThe observation included 105 patients (average age 34.1 ± 0.8 years), which had been examined by epidemiological, clinical (including PORT prognostic scale) according to European Respiratory Society requirements, serological test for CMV IgM, IgG detection and antibiotic usage questionnaire for a 3-month period prior CAP.Results76.2% (n= 80) CAP patients had positive CMV IgG. CMV-positive patients were characterized by higher severity outcome risk in the nearest future versus CMV-negative ones (P< 0.0001): third risk class—14.9 times higher, fourth risk class—10.5 times higher. CMV IgG–positive results correlated with the CAP severity level (r(Spearman) = 0.472). In total, 51.4% (n= 54, among them 47 CMV-positive patients) mentioned antibiotic use during the last 3 months prior to CAP. During the CAP treatment, 75.0% (n= 60) of CMV-positive patients and 20.0% (n= 5) of CMV-negative ones did not respond to antibiotic treatment by cephalosporin and quinolone lines and needed changes in aetiology prescription according to antibiotic susceptibility microbial test. 61.3% (n= 47) of CAP patients (everybody was after medication replacement) got adverse events like antibiotic-associated diarrhoea (16 cases), QT prolongation in ECG (17 cases), creatinine, urea elevation (11 cases) and alanine/aminotransferase elevation (5 cases).ConclusionsCMV persistence is associated with higher risk of severe CAP among young patients without comorbid pathologies and contributes to the antibiotic resistance creation as well as related side effects.