Why would a 4 year old be diagnosis w pseudomonas from a sputum culture?

Pneumonia: Pseudomonas causes lung infections, including pneumonia. Children with cystic fibrosis are especially susceptible to pseudomonas infections. It would be prudent to discuss with the child's doctor.

Extremely unusual: This is unusual as the children hardly ever get such infections. This is usually in children that have been chronically ill or have been in hospital with such illness and asthma or cystic fibrosis. suggestive of respiratory type illness or someone who is immunocompromised.