Incorporation of Farnesol Significantly Increases the Efficacy of Liposomal Ciprofloxacin against Pseudomonas aeruginosa Biofilms in Vitro

Abstract

The challenge of eliminating Pseudomonas aeruginosa infections, such as in cystic fibrosis lungs, remains unchanged due to the rapid development of antibiotic resistance. Poor drug penetration into dense P. aeruginosa biofilms plays a vital role in ineffective clearance of the infection. Thus, the current antibiotic therapy against P. aeruginosa biofilms need to be revisited and alternative antibiofilm strategies need to be invented. Fungal quorum sensing molecule (QSM), farnesol, appears to have detrimental effects on P. aeruginosa. Thus, this study aimed to codeliver naturally occurring QSM farnesol, with the antibiotic ciprofloxacin as a liposomal formulation to eradicate P. aeruginosa biofilms. Four different liposomes (with ciprofloxacin and farnesol, Lcip+far; with ciprofloxacin, Lcip; with farnesol, Lfar; control, Lcon) were prepared using dehydration-rehydration method and characterized. Drug entrapment and release were evaluated by spectrometry and high performance liquid chromatography (HPLC). The efficacy of liposomes was assessed using standard biofilm assay. Liposome-treated 24 h P. aeruginosa biofilms were quantitatively assessed by XTT reduction assay and crystal violet assay, and qualitatively by confocal laser scanning microscopy (CLSM) and transmission electron microscopy (TEM). Ciprofloxacin release from liposomes was higher when encapsulated with farnesol (Lcip+far) compared to Lcip (3.06% vs 1.48%), whereas farnesol release was lower when encapsulated with ciprofloxacin (Lcip+far) compared to Lfar (1.81% vs 4.75%). The biofilm metabolism was significantly lower when treated with Lcip+far or Lcip compared to free ciprofloxacin (XTT, P < 0.05). When administered as Lcip+far, the ciprofloxacin concentration required to achieve similar biofilm inhibition was 125-fold or 10-fold lower compared to free ciprofloxacin or Lcip, respectively (P < 0.05). CLSM and TEM confirmed predominant biofilm disruption, greater dead cell ratio, and increased depth of biofilm killing when treated with Lcip+far compared to other liposomal preparations. Thus, codelivery of farnesol and ciprofloxacin is likely to be a promising approach to battle antibiotic resistant P. aeruginosa biofilms by enhancing biofilm killing at significantly lower antibiotic doses.

Control of the Lung Residence Time of Highly Permeable Molecules after Nebulization: Example of the Fluoroquinolones

“…For example, the incorporation of farnesol, a natural quorum sensor inhibitor, and CIP in a liposomal formulation exhibited a very interesting outcome. The minimum biofilm eradicating concentration (MBEC) value against PA01 obtained using the co-delivery system was reported at 0.128 µg/mL of CIP, essentially the same as its reported MIC value against planktonic bacteria [109]. Finally, despite disappointing clinical trials (ORBIT and RESPIRE), the controlled release strategy is still encouraging but needs further developments.…”

Inhibitory effects of fruit berry extracts on Streptococcus mutans biofilms

“…Indirect quantification of the metabolic activity of biofilm cells was obtained from a colorimetric assay that is based on bioreduction of the tetrazolium salt, 2,3‐bis (2‐methoxy‐4‐nitro‐5‐sulfophenyl)‐5‐[(phenylamino) carbonyl]‐2H‐tetrazolium hydroxide (XTT), to a colored formazan product, the absorbance of which can be measured spectrophotometrically . Briefly, XTT (Sigma‐Aldrich, St Louis, MO, USA) salt solution (1 mg ml −1 in PBS) was prepared, filter‐sterilized (0.22 μ m pore‐size filter), and stored at −80°C until required.…”

Future therapies targeted towards eliminatingCandidabiofilms and associated infections

“…Noteworthy here is the recently shown therapeutic benefits of inter-kingdom signalling molecules as biofilm disrupters, and antimicrobial adjuncts in eliminating bacterial biofilms in the respiratory tract [217]. Similar approaches are worth investigating for managing Candida biofilm infections.…”