Luteolin loaded PEGylated cerosomes: a novel treatment for MRSA skin infections

Methicillin-resistant Staphylococcus aureus (MRSA) is a major cause of skin and soft tissue infections which, due to the spread of antimicrobial resistance, have become increasingly serious. Bacterial skin infection affects the barrier function of skin causing depletion of the ceramide content in the stratum corneum (SC) of the epidermis. In the study reported herein, luteolin (LUT) a naturally-occurring flavonoid was incorporated in PEGylated cerosomes (PCs) to boost its antibacterial action as a topical application. The opimal formulation of the surface-modified lipidic vesicles was chosen with the aid of a 2³ full factorial design. The effectiveness of the optimal LUT formulation which was developed was evaluated using several MRSA strains both in vitro and in vivo studies.

A 2³ full factorial design was employed for the preparation of the optimum PC formulation, designated herein as F5. A comparative in vitro release study revealed the superiority of F5 over a LUT suspension in solubilizing and releasing after 24 h, a higher percentage 78.1 ± 1.8% of luteolin compared with only 18.3 ± 2.1% for the luteolin suspension. When tested against MRSA strains, F5 showed antimicrobial activity that was higher than that of the luteolin suspension, having a MIC value of 187.5 µg/mL versus 1500 µg/mL. In addition to having enhanced anti-virulence activity than the luteolin suspension in terms of antibiofilm formation (with % inhibition ranging from 45 to 99% with the tested strains at 0.5 × and 0.25 × MICs, where the luteolin suspension only had a range from 1 to 45%), enhanced anti-pigment production, and anti-α-hemolysin activity were also observed. Moreover, F5 affected the cell wall integrity as confirmed by transmission electron microscopy (TEM). Scanning electron microscopy (SEM) verified the effect of F5 on bacterial biofilm formation, showing reduction of cellular adhesion and disruption of biofilm, factors which greatly contribute to bacterial pathogenesis and antibiotic resistance. When compared to the negative control and the luteolin suspension groups, the F5 formulation also resulted in reducing the bacterial load in the murine skin infection model.

F5 PEGylated cerosomes are potential new potent defense agents against MRSA infections, demonstrating promising therapeutic capabilities.