Evaluation of Clinical, Laboratory, and Radiologic Parameters Affecting Antibiotic Use and Associated Cost in RSV-Positive Children with Acute Lower Respiratory Tract Infections

Background & objectives: Acute lower respiratory tract infections (LRTIs) are a major cause of morbidity and mortality in children under five years of age. Respiratory syncytial virus (RSV) is the leading viral pathogen in infants, yet empirical antibiotics are often prescribed due to difficulty distinguishing bacterial from viral infections. This study aimed to determine clinical, laboratory, and radiologic parameters influencing antibiotic continuation and to evaluate associated costs in RSV-positive infants. Methods: We retrospectively reviewed records of 209 hospitalized infants aged 1–24 months with RSV infection confirmed by multiplex polymerase chain reaction (mPCR) at a tertiary pediatric hospital between April 2017 and April 2021. Patients with co-infections or other exclusion criteria were omitted. Data on demographics, comorbidities, clinical features, laboratory and radiologic findings, treatments, and costs were analyzed. Multivariate logistic regression identified independent predictors of antibiotic continuation. Results: Overall, 69.4% of patients received antibiotics; intravenous β-lactams were most common. Prolonged antibiotic administration showed a significant relationship with elevated C-reactive protein (CRP) values both at the time of admission and at peak measurement (p = 0.003 and p = 0.001, respectively), as well as with the presence of alveolar infiltrates on chest radiographs (p = 0.016). Patients in whom antibiotics were continued had notably longer median hospital stays, extended antibiotic treatment durations, and higher treatment-related costs (all p < 0.01). Conclusions: Antibiotic continuation in RSV-positive infants was primarily driven by elevated CRP and radiologic findings, highlighting the need for evidence-based prescribing to reduce unnecessary antibiotic use and associated costs. Incorporating rapid molecular diagnostics into routine care may improve decision-making and support antimicrobial stewardship.