ABSTRACT:
The aim of this study was to evaluate the synergistic effects of each of N-acetylcysteine (NAC) and ambroxol with ciprofloxacin, cefoperazone, tobramycin, amikacin and imipenem against pre-formed biofilms formed by five clinical isolates of Pseudomonas aeruginosa. The antibiofilm effect of the antibiotics was tested by determination of minimum regrowth concentration (MRC). Ambroxol showed more potentiating activity of antibiotics than that of NAC. The biofilm regrowth inhibiting activity of the antibiotics was augmented by up to 16-256 folds in the presence of sub-MRCs of ambroxol and by up to 4-256 folds in the presence of sub-MRCs of NAC. In the presence of sub-MRCs of ambroxol, imipenem was the most potentiated (with up to 4-512 folds decrease in MRCs), followed by cefoperazone (8-256 folds), ciprofloxacin and amikacin (up to 4-32 folds), while the lowest decrease in MRCs was found for the combination of tobramycin with ambroxol (2-16 folds). On the other hand, in the presence of NAC, tobramycin was the most augmented antibiotic (MRCs were decreased by up to 4-256 folds), followed by imipenem (up to 2-128 folds), amikacin (up to 2-64 folds) and cefoperazone (up to 8-32 folds), while ciprofloxacin was the least potentiated (with up to 2-4 folds decrease in MRCs). Our results suggest that the combinations of antibiotics with these mucolytics can be beneficial in treatment of biofilm infections.