Biocidal Cationic Macromolecules Irrespective of Bacterial Resistance: Our Best Achievements

Since new antibacterial agents against multi-drug resistant (MDR) bacteria are urgently needed, we recently synthetized cationic dendrimers and copolymers and assessed their antibacterial activity on numerous MDR clinical isolates. Being cationic, the prepared macromolecules electrostatically interacted with pathogens’ surfaces, causing irreversible damages and rapid bacterial death. A lysine dendrimer having 192 cationic groups (N+) was strongly active preferentially on non-fermenting Gram-negative species, displaying MICs comparable to colistin against P. aeruginosa (2.1 µM). A lysine dendrimer (128 N+) was explicitly active on Acinetobacter, while a cationic copolymer showed remarkable antibacterial activity against numerous Gram-positive and Gram-negative species. In 24 h-time-killing experiments, all of the mentioned macromolecules displayed rapid bactericidal effects, while when tested on human keratinocytes, especially G5-PDK, showed low levels of cytotoxicity and high values of selectivity indices. Due to their physicochemical properties and bactericidal potency, the herein reviewed cationic macromolecules could represent novel tools for realizing either a targeted or a broad-spectrum bactericidal action, regardless of the bacterial resistance to current antibiotics.