Anticandidal Activity of Omiganan and Its Retro Analog Alone and in Combination with Fluconazole

Vulvovaginal candidiasis (VVC) is a vaginal infection that manifests itself as several symptoms which can lead to various life-threatening complications. The majority of VVC is caused by Candida albicans strains, and it is estimated that approximately 75% of women worldwide would suffer from this condition at least once during their lifetime. Surprisingly, the detailed pathomechanism of yeast-like fungi invasions in vagina is not yet fully understood. However, the ability to form biofilm on vaginal mucosa is considered as one of the critical factors associated with failure of the therapy and recurrences of the disease. Antimicrobial peptides (AMPs) are a promising class of compounds that are receiving a growing interest owing to their antibacterial, antifungal, and antibiofilm properties. Omiganan is a synthetic analog of Indolicidin that is characterized by wide spectrum of antimicrobial and antibiofilm activities. Recent reports suggest improved activity of analogs with a reversed sequence (retro-analog concept). Therefore, Omiganan and its retro analog were tested against planktonic forms and biofilm of 18 Candida strains isolated from VVC. Moreover, the synergy between the AMPs and fluconazole was studied as well. The AMPs appeared to be effective against C. albicans biofilm, and the reversion of the sequence generally led to an improved antimicrobial activity. Furthermore, confocal and scanning electron microscopic visualizations revealed the effectiveness of AMPs-fluconazole combinations also against fluconazole-resistant strains.