Dear Collegues,

Antimicrobial resistance has been recognized as one of the most serious global threats to human health. The ability of Gram-negative bacteria to acquire resistance to antimicrobials via horizontal gene transfer and mutation is a real threat to and burden on the health and economy. Even though they are most commonly detected in hospital settings, multidrug-resistant Gram-Negative bacteria have also been described in other ecological niches. The epidemiology of Gram-negative bacteria is complex, and the importance of an integrated surveillance system based on the One Health approach has been widely recognized. The use of antimicrobials in medicine, agriculture, and livestock has favored the selection of these pathogens. Additionally, increases in hospitalization and the indiscriminate use of antimicrobials during the COVID-19 pandemic may have contributed to increased rates of multidrug-resistant Gram-negative bacteria. Thus, the effects of antimicrobial resistance in public health and in the economy in the short and medium term are enormous. Efforts must focus on implementing new policies and control programs on how to use and dispense antibiotics. Furthermore, understanding resistance mechanisms and epidemiology is critical for the development of the novel antibacterial products needed to meet future demands. This Special Issue invites manuscript submissions that further our understanding of antimicrobial resistance in Gram-negative bacteria. Submissions on the search for new drugs developed through structural modification agents, production of synthetic derivatives, or repositioning are especially encouraged.