Final answer:
The most common pathogen in younger children with cystic fibrosis is Haemophilus influenzae, while Pseudomonas aeruginosa is a common concern in older children and adults. These pathogens can cause serious infections due to the buildup of mucus in the lungs, which is characteristic of CF.
Step-by-step explanation:
The most common pathogen in younger children with cystic fibrosis (CF) is Haemophilus influenzae, as evidenced by the case of young Tracy who developed a serious cough that was later identified to be bacterial pneumonia caused by this bacterium. In older children and adults with CF, the suspect pathogen often is Pseudomonas aeruginosa. This bacterium is problematic due to its high resistance to antibiotics and its ability to form biofilms in the lungs, leading to chronic inflammation and lung damage, which is a leading cause of mortality in CF patients. Pseudomonas aeruginosa does not grow in the absence of oxygen, indicating that it is an aerobic organism. In CF, the thick mucus in the lungs creates an environment that incapacitates the lung's defenses, making infection more likely.
Respiratory syncytial virus (RSV) can cause severe infections in very young children and is another pathogen to be aware of. However, it is typically more of a concern for viral pneumonia rather than bacterial pneumonia. Knowing the common pathogens that affect CF patients is crucial for proper diagnosis and treatment, as the buildup of dry mucus due to the defective cystic fibrosis transmembrane receptor (CFTR) creates a breeding ground for these pathogens.