XF drugs: A new family of antibacterials

The emerging increase of antibiotic resistance constitutes an important risk to human health. Two million patients acquire nosocomial infections in U.S. hospitals each year. Of these infections, 60% involve resistant bacteria. In the last decade, only a few new antibiotics with new mechanisms of action were approved by the FDA, but additional costs for preventing the spread of bacteria, side effects and resistance may limit their long-term usefulness. Therefore, the number of therapeutic options is limited and necessitates exploration of novel antibacterial agents/approaches to treat hospital- and community-acquired infections. The challenge in antibacterial research is to find appropriate structurally novel antibacterial agents inhibiting bacterial targets. The XF drug series, having a dicationic porphyrin structure, which is distinct from all other known antibiotic classes, are rapidly active against a broad range of bacteria. Another new strategy is called photodynamic inactivation of bacteria (PDIB), which utilizes visible light in combination with photosensitizing molecules to efficiently kill bacteria via reactive oxygen species. The XF drugs act additionally as photosensitizers to inactivate bacteria upon light activation. This review summarizes the efficacy of the XF series and describes it as a new class of antibacterial agents or as new photo-sensitizers.