Assessment on the Effects of Glycerol Monolaurate on the Antibacterial and Beta-Lactamase blaTEM and blaSHV Gene Expression in Multidrug-Resistant Klebsiella pneumoniae

The alarming rise of antimicrobial resistance (AMR) has driven researchers to explore alternatives that can replace antimicrobial agents. Natural antimicrobials are considered promising due to their safety, sustainability, and abundance in the environment. Among the various natural antimicrobials being explored, glycerol monolaurate (GML) has encouraged the investigation of its potential antibacterial properties. This study aimed to determine the antibacterial activity of GML against multidrug-resistant (MDR) Gram-negative Klebsiella pneumoniae. and to evaluate their gene expression activity on both blaSHV and blaTEM genes. The broth microdilution method, with slight modification, was used to determine the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of GML, while the gene expression analysis was performed using RT-qPCR. In this study, no MIC or MBC was observed in all tested GML concentrations, indicating a lack of direct antibacterial activity against Klebsiella pneumoniae. However, transcriptional analysis demonstrated a significant downregulation of the blaTEM gene, but an insignificant downregulation of the blaSHV gene. These findings suggest that GML may reduce the resistance mechanism at the transcriptional level by modulating the expression of the beta-lactamase gene, despite lacking a direct bactericidal effect. This highlights the potential of GML as a gene expression modulator and adjuvant candidate in combination therapy, rather than as a direct antimicrobial agent.