Which of the following is NOT a chronic infective species commonly associated with cystic fibrosis?

In the context of cystic fibrosis, certain organisms are recognized as chronic infective species that frequently colonize the lungs and contribute to respiratory complications. Among them, Pseudomonas aeruginosa is the most notorious due to its adaptability and ability to form biofilms, which make eradication difficult. Staphylococcus aureus can also be a significant pathogen, particularly in early childhood, and has the potential to cause chronic infections.

Aspergillus species, while not classic bacterial pathogens, are often associated with allergic fungal sinusitis in patients with cystic fibrosis and can lead to bronchopulmonary infections, especially in those with significant lung disease.

Klebsiella, on the other hand, is not commonly considered a chronic pathogen in the context of cystic fibrosis. It can cause infections, but it does not typically persist in the lungs of these patients in the same way that the other organisms listed do. Therefore, Klebsiella is correctly identified as not being a chronic infective species commonly associated with cystic fibrosis, distinguishing it from the more frequently encountered pathogens.