In infants and young children with cystic fibrosis, which pathogen is most commonly isolated from sputum cultures?

In infants and young children with cystic fibrosis, Staphylococcus aureus is the pathogen that is most commonly isolated from sputum cultures. This pathogen is known for its capacity to colonize the airways of patients with cystic fibrosis early in life.

Cystic fibrosis, a genetic disorder affecting the lungs and digestion, leads to thick and sticky mucus production, creating an environment conducive to bacterial growth. Staphylococcus aureus, especially in its methicillin-sensitive and methicillin-resistant forms, is prevalent in these patients due to its ability to thrive in the abnormal pulmonary secretions. Early colonization by this bacterium can lead to chronic infections and contribute to the progressive lung disease commonly seen in cystic fibrosis patients.

While Pseudomonas aeruginosa is also a significant pathogen in cystic fibrosis patients, typically isolated in older children and adults as the disease progresses and the lung environment changes, Staphylococcus aureus is more frequently found in younger patients, making it the primary isolate in the early stages of infection.