Gold Nanoclusters for Targeting Methicillin‐Resistant <i>Staphylococcus aureus</i> In Vivo

Abstract Widespread multidrug resistance caused by the abuse of antibiotics calls for novel strategies and materials. Gold nanoclusters (AuNCs) are scarcely explored for combating multidrug‐resistant (MDR) bacteria in vivo. We herein synthesized a novel class of AuNCs, namely quaternary ammonium (QA) capped AuNCs (QA‐AuNCs) as potent antibiotics selectively targeting MDR Gram‐positive bacteria, including methicillin‐resistant Staphylococcus aureus (MRSA) and vancomycin‐resistant Enterococci (VRE), in vivo. QA‐AuNCs kill bacteria through a combined physicochemical mechanism, and show excellent therapeutic effects in both a skin infection model and a bacteremia model induced by MRSA. In addition, owing to their intense fluorescence, QA‐AuNCs can be used for the discrimination of live/dead bacteria and bacteria counting, suggesting their potential for clinical theranostics.