Is the improvement of CF patients, hospitalized for pulmonary exacerbation, correlated to a decrease in bacterial...

Area of Science:

• Medical Microbiology
• Pulmonology
• Infectious Diseases

Background:

• Cystic Fibrosis (CF) patients are susceptible to Pseudomonas aeruginosa airway colonization.
• Chronic P. aeruginosa colonization leads to recurrent pulmonary exacerbations requiring hospitalization and intravenous antibiotics.
• Standard antibiotic treatment typically results in patient health improvement.

Purpose of the Study:

• To determine the correlation between clinical improvement in CF patients and changes in P. aeruginosa and total bacterial load in sputum.
• To investigate the impact of lung function on bacterial load reduction during treatment.

Main Methods:

• Studied 18 CF patients during 27 hospitalization episodes for exacerbations.
• Assessed inflammation and lung function parameters (FEV1) on days 1, 8, and 15.
• Quantified P. aeruginosa load using culture, quantitative PCR (qPCR), and propidium monoazide qPCR.

Main Results:

• Patients showed significant clinical improvement within one week, with normalized inflammation markers and increased FEV1.
• Both P. aeruginosa and total bacterial loads decreased significantly (p<0.05) in the first week of treatment.
• Patients with low lung function (FEV1≤39.4%) did not exhibit a significant decrease in P. aeruginosa load.
• Propidium monoazide qPCR revealed that 62% of P. aeruginosa cells were non-cultivable, suggesting dormancy or structural integrity despite non-viability.

Conclusions:

• Clinical improvement in CF patients correlates with a reduction in P. aeruginosa load, primarily during the first week of antibiotic therapy.
• The reduction in P. aeruginosa load is not observed in patients with compromised lung function.
• A significant proportion of P. aeruginosa detected by qPCR are non-cultivable, indicating the presence of dormant or dead but intact cells.