In adolescents with cystic fibrosis, which bacteria is most likely to be isolated causing lung infections?

In adolescents with cystic fibrosis, Pseudomonas aeruginosa is the bacteria most likely to be isolated in lung infections due to its unique characteristics and pathogenicity in this population. Cystic fibrosis leads to mucus accumulation in the lungs, creating an environment that is favorable for certain bacteria. Pseudomonas aeruginosa is particularly adept at thriving in the thick, sticky secretions that characterize cystic fibrosis. It has a number of virulence factors that allow it to adhere to and colonize the respiratory epithelium effectively.

Over time, patients with cystic fibrosis often develop chronic infections with Pseudomonas aeruginosa, which can lead to a decline in lung function and increased morbidity. This bacterium is known for its resistance to multiple antibiotics and its role in exacerbating lung disease in these patients.

In contrast, the other listed bacteria—Listeria monocytogenes, Haemophilus influenzae, and Streptococcus pneumoniae—are less commonly associated with chronic lung infections in cystic fibrosis patients. While they can cause respiratory infections in general populations, they do not exhibit the same level of persistence and associated complications seen with Pseudomonas aeruginosa in cystic fibrosis.