Gallium: a Decisive "Trojan Horse" Against Microorganisms

Controlling multidrug-resistant microorganisms (MRM) has a long history with the extensive and inappropriate use of antibiotics. At the cost of these drugs being scarce, new possibilities have to be explored to inhibit the growth of microorganisms. Thus, metallic compounds have shown to be promising as a viable alternative to contain pathogens resistant to conventional antimicrobials. Gallium (Ga) can be highlighted, which is an antimicrobial agent capable of disrupting the essential activities of microorganisms, such as metabolism, cellular respiration and DNA synthesis. It was observed that this occurs due to the similar properties between Ga and iron (Fe), which is a fundamental ion for the correct functioning of bacterial activities. The mimetic effect performed by Ga prevents iron transporters from distinguishing both ions and results in the substitution of Fe for Ga and in adverse metabolic disturbances in rapidly growing cells. This review focuses on analyzing the development of research involving Ga, elucidating the intracellular incorporation of the "Trojan Horse", summarizing the mechanism of interaction between gallium and iron and comparing the most recent and broad-spectrum studies using gallium-based compounds with antimicrobial scope.