Designing an ultra-short antibacterial peptide with potent activity against Mupirocin-resistant MRSA.

Staphylococcus aureus is the pathogen responsible for the majority of human skin infections. In particular, the methicillin-resistant variety, MRSA, has become a global clinical concern. The extensive use of mupirocin, the first-line topical antibacterial drug of choice, has led to the emergence of mupirocin-resistant MRSA globally, resulting in the urgent need for a replacement. Antimicrobial peptides are deemed plausible candidates. Herein, we describe a structure-activity relationship approach in the design of an ultra-short peptide with potent anti-MRSA activity with a rapid, bactericidal mode of action. Coupled to a low cytotoxic activity, we believe our lead compound can be developed into a topical antibacterial agent to replace mupirocin as the first-line drug for treating MRSA skin infections.

Structure-activity relationship studies of ultra-short peptides with potent activities against fluconazole-resistant Candida albicans.

Vulvovaginal candidiasis (VVC) is a genital fungal infection afflicting approximately 75% of women globally and is primarily caused by the yeast Candida albicans. The extensive use of fluconazole, the first-line antifungal drug of choice, has led to the emergence of fluconazole-resistant C. albicans, creating a global clinical concern. This, coupled to the lack of new antifungal drugs entering the market over the past decade, has made it imperative for the introduction of new antifungal drug classes. Peptides with antifungal properties are deemed potential drug candidates due to their rapid membrane-disrupting mechanism of action. By specifically targeting and rapidly disrupting fungal membranes, they reduce the chances of resistance development and treatment duration. In a previous screening campaign involving an antimicrobial peptide library, we identified an octapeptide (IKIKIKIK-NH2) with potent activity against C. albicans. Herein, we report a structure-activity relationship study on this peptide with the aim of designing a more potent peptide for further development. The lead peptide was then tested against a panel of fluconazole-resistant C. albicans, subjected to a fungicidal/static determination assay, a human dermal fibroblast viability assay and a homozygous profiling assay to gain insights into its mechanism of action and potential for further development as a topical antifungal agent.