What is the next imaging investigation required?
Nothing acutely. The child should be treated with antibiotics and may authors suggest that no further imaging is required. Some advocate a repeat chest x-ray to ensure resolution.
What infective agent is usually responsible?
The infective agent is bacterial but not specific to any particular organism. Streptococcus pneumoniae is the most common causative entity.
What is the pathogenesis of round pneumonia? Why is it mostly seen in children?
Some controversy exists as to the cause of round pneumonia. The most commonly proposed theory is due to absence/paucity of collateral air communicating pathways in children (i.e. pores of Kohn, canals of Lambert) which limit spread of infection.
Rounded region of consolidation is seen in the right anterior segment of the upper lobe.