Introduction:
The aim of this study was to identify clinical, demographic, and laboratory factors associated with the initiation of antibiotic therapy in children hospitalized with confirmed adenoviral upper respiratory tract infection, as well as to assess determinants of potentially avoidable antibiotic use.

Material and methods:
A retrospective, single-center observational study was conducted based on medical records of children aged 0–18 years hospitalized between 2019 and 2025 in a pediatric infectious diseases department. Inclusion required a diagnosis of adenoviral infection confirmed by antigen testing. Patients with concomitant bacterial infections requiring antibiotics were excluded. Collected data included age, sex, day of illness at admission, and C-reactive protein (CRP) levels. Antibiotic use before and during hospitalization was analyzed. Statistical analysis included the Mann-Whitney U test and χ2 test, with p < 0.05 considered significant.

Results:
Eighty children were included in the analysis. Overall, 60% of patients received antibiotics, most frequently prior to hospital admission. No statistically significant difference in CRP levels was observed between children treated and not treated with antibiotics (p = 0.24). In contrast, age was significantly associated with antibiotic administration; antibiotics were used in 84% of children older than 2 years compared with 40% of younger patients. A decreasing trend in antibiotic use was observed over the study period, from 89% in 2019–2022 to 50% in 2025.

Conclusions:
Antibiotic use in adenoviral infections was primarily driven by clinical presentation rather than objective inflammatory markers. C-reactive protein was not a reliable predictor of antibiotic initiation. The observed temporal decline in antibiotic use suggests improving stewardship practices. Early and wider implementation of rapid adenoviral diagnostics may further reduce unnecessary antibiotic therapy.