Functional characterization of the chaperone DnaK of Riemerella anatipestifer in antibiotic resistance and pathogenicity.

Antibiotic resistance has become a global public health problem, which is closely related to humans, animals and the environment. Riemerella anatipestifer (R. anatipestifer, RA) is a Gram-negative, multi-resistant bacterium that infects ducks and other birds. However, the mechanisms underlying R. anatipestifer's resistance to antibiotics aren't fully to be understood. Here, we show that the R. anatipestifer dnaK-deficient strain (∆dnaK) is more sensitive than the wild type to various tested antibacterial agents. DnaK is important for alleviating oxidative stress damage, which has been shown to be necessary for efficient scavenging of reactive oxygen species (ROS) induced by bactericidal antibiotics. Furthermore, it is also essential for maintaining normal cell morphology and membrane permeability. Finally, the chaperone DnaK is also critical for the pathogenicity of R. anatipestifer, since it is required for the heat stress resistance inside ducks. Taken together, this study is important to provide strategies against the emergence of antimicrobial resistance and R. anatipestifer infection.