Synergistic Antimicrobial Effects of Ibuprofen Combined with Standard-of-Care Antibiotics against Cystic Fibrosis Pathogens

Abstract

Cystic fibrosis (CF) is a common life-shortening genetic disease caused by mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) gene. Lungs of CF patients are often colonized or infected with microorganisms requiring frequent courses of antibiotics. Antibiotic-resistant bacterial infections have been a growing concern in CF patients. Chronic bacterial infections and concomitant airway inflammation damage the lungs, ultimately leading to respiratory failure. Several clinical trials have demonstrated that high-dose ibuprofen reduces the rate of pulmonary function decline in CF patients. This beneficial effect has been attributed to the anti-inflammatory properties of ibuprofen. Previously, we have confirmed that high-dose ibuprofen demonstrates antimicrobial activity against P. aeruginosa both in vitro and in vivo. However, no study has examined the antimicrobial effect of combining ibuprofen with standard-of-care antimicrobials. Here, we evaluated the possible synergistic activity of combinations of common nonsteroidal anti-inflammatory drugs (NSAIDs), namely, ibuprofen, naproxen, and aspirin, with commonly used antibiotics for CF patients. The drug combinations were screened against different CF clinical isolates. Antibiotics that demonstrated increased efficacy in the presence of ibuprofen were further tested for potential synergistic effects between these NSAIDS and antimicrobials. Finally, a survival analysis of a P. aeruginosa murine infection model was used to demonstrate the efficacy of the most potent combination identified in in vitro screening. Our results suggest that combinations of ibuprofen with commonly used antibiotics demonstrate synergistic antimicrobial activity against drug-resistant, clinical bacterial strains in vitro. The efficacy of the combination of ceftazidime and ibuprofen against resistant P. aeruginosa was demonstrated in an in vivo pneumonia model.

Keywords: NSAIDS; Pseudomonas aeruginosa; aspirin; ceftazidime; cystic fibrosis; ibuprofen; naproxen; synergy.

Figure 1

Endpoint CFU study demonstrates synergy between naproxen and antibiotics. Synergy demonstrated between naproxen and (A) aztreonam, (B) ceftazidime, and (C) amikacin against PA HP3 and EM 2-18 by endpoint CFU study after 24 h incubation with the drug concentration ratios (in μg/mL) indicated under each panel. Data are shown as mean and standard deviation (n = 6). Statistical significance determined by one-way ANOVA followed by Tukey’s multiple comparison test (** indicates p ≤ 0.01, *** indicates p ≤ 0.001, and **** indicates p ≤ 0.0001).

Figure 2

Endpoint CFU study demonstrates synergy between ibuprofen and antibiotics. Synergy demonstrated between ibuprofen and (A) aztreonam, (B) ceftazidime, and (C) amikacin against PA HP3 and EM 2-18 by endpoint CFU study after 24 h incubation with the drug concentration ratios (in μg/mL) indicated under each panel. Data are shown as mean and standard deviation (n = 6). Statistical significance determined by one-way ANOVA followed by Tukey’s multiple comparison test (*** indicates p ≤ 0.001, and **** indicates p ≤ 0.0001).

Figure 3

The addition of high-dose ibuprofen to ceftazidime improves survival in a pneumonia model. The combinational therapy of ibuprofen and ceftazidime resulted in a significant survival advantage for mice intranasally inoculated with the P. aeruginosa isolate PA HP3 (n = 6). Statistical significance was determined by Mantel–Cox test (** indicates p ≤ 0.01).