**3. Mechanisms of action of repurposing drugs against Gram-negative bacilli**

Different agents are promising both in vitro and in vivo candidates to be repositioned as antimicrobial agents to treat infections caused by MDR Gram-negative bacilli. A variety of drugs with different mechanisms of action and targets have been selected including: DNA, RNA and proteins inhibitors [16–20], QS regulators [15, 17, 21–25], biofilm formation inhibitors and disruptors [26, 27], drugs that interact with cell membrane [28–30], drugs that interact with iron metabolism [31–35], and host immune system modulators [36–39]. These drugs and their mechanisms of action against critical-priority pathogens (*A. baumannii*, *P. aeruginosa* and *Enterobacterales*) are summarized in **Figure 1** and **Table 1**.
