Abstract:Second messengers play important roles in the physiological activities of bacteria. 3',5'-cyclic adenosine monophosphate (cAMP) as a second messenger exists ubiquitously in bacteria. Under normal physiological conditions, the synthesis and metabolism of cAMP in bacterial cells are in dynamic balance, and cAMP functions as a transcription regulator by forming complexes with its receptor protein Crp. This article reviews the regulatory mechanisms of cAMP-Crp in lethal stress response, bacterial population competition, and biofilm formation, as well as the pathways through which cAMP affects the virulence of different pathogens. It calls for researchers to pay attention to the upstream pathways of bacterial cAMP in response to host or external environmental changes. Comprehensively understanding the cAMP-mediated bacterial stress responses and virulence regulation may contribute to the prevention and treatment of bacterial infections.