Although signs and symptoms may become severe, most viral respiratory infections of infancy are self-limited and improvement usually occurs within several days. Patients hospitalized with viral pneumonia usually require supportive therapy, including oxygen and fluids, and eventually mechanical ventilation. Bacterial superinfection can occur, accompanied by purulent sputum production and isolation of pathogenic bacteria from sputum. Streptococcus pneumoniae, Haemophilus influenzae, Moraxella catarrhalis and Staphylococcus aureus are the most common secondary invaders. Appropriate antibiotherapy must be administrated after cultures. There is no evidence that prophylactic antibiotherapy is of any use to prevent bacterial superinfection in viral pneumonia.