Imipenem exposure influence the expression of quorum sensing receptor sdiA in Escherichia coli.

The increasing trend of carbapenem resistance amongst Escherichia coli poses a major public health crisis and requires active surveillance of resistance mechanisms to control the threat. Quorum Sensing system plays a role in bacterial resistance to antibiotics. Quorum Sensing is a cell-cell communication system where bacteria alter their gene expression in response to specific stimuli. Here, in this study we investigated the transcriptional response of quorum sensing receptor, sdiA in E.coli under sub-inhibitory concentration of carbapenem in presence of quorum sensing signal molecules. Two E.coli isolates harbouring blaNDM were subjected to treatment with 10% SDS for 20 consecutive days of which blaNDM encoding plasmid was successfully eliminated from one isolate. Both the wild type and the cured mutant were then allowed to grow under eight different inducing conditions and the transcriptional response of sdiA gene was studied by quantitative real time PCR method. We found different response levels of sdiA in wild type and cured mutant under exogenous AHL and imipenem and when co-cultured with P.aeruginosa under imipenem stress. This study highlighted that sub-inhibitory concentration of imipenem in combination with AHL is acting as signal to SdiA, a quorum sensing receptor in E.coli.