Assessment on the Effects of Glycerol Monolaurate on the Antibacterial and Beta-Lactamase blaTEM and blaSHV Gene Expression in Multidrug-Resistant Klebsiella pneumoniae
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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.
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Al-Hashimy A B and Al-Musawy W K. (2020). Molecular study and antibiotic susceptibility patterns of some extended spectrum beta-lactamase genes (ESBL) of Klebsiella pneumoniae in urinary tract infections. Journal of Physics: Conference Series 1660: 012017. https://doi.org/10.1088/1742-6596/1660/1/012017
CDC. (2024). About ESBL-producing Enterobacterales. https://www.cdc.gov/esbl-producing-enterobacterales/about/index.html (accessed 10 October 2025).
Chen H, Sapula S A, Turnidge J and Venter H. (2025). The effect of commonly used non-antibiotic medications on antimicrobial resistance development in Escherichia coli. NPJ Antimicrobials and Resistance 3(1): 73. https://doi.org/10.1038/s44259-025-00144-w
European Committee on Antimicrobial Susceptibility Testing (EUCAST). (2024). EUCAST reading guide for broth microdilution. https://www.eucast.org/fileadmin/eucast/pdf/MIC/Reading_guide_BMD_v_5.0_2024.pdf (accessed 10 October 2025).
Food and Drug Administration. (2025). Substances added to food. https://www.hfpappexternal.fda.gov/scripts/fdcc/index.cfm?set=FoodSubstances&id=LAURICACID (accessed 10 October 2025).
Garcia-Ruiz J and Ryadnov M G. (2022). DANAMIC: Data analyzer of minimum inhibitory concentrations: Protocol to analyze antimicrobial susceptibility data. STAR Protocols 3 (4): 101782. https://doi.org/10.1016/j.xpro.2022.101782
Gomes A É I, Stuchi L P, Siqueira N M G, Henrique J B, Vicentini R, Ribeiro M L, Darrieux M and Ferraz L F C. (2018). Selection and validation of reference genes for gene expression studies in Klebsiella pneumoniae using reverse transcription quantitative real-time PCR. Scientific Reports 8(1): 9001. https://doi.org/10.1038/s41598-018-27420-2
Hudzicki J. (2009). Kirby-Bauer disk diffusion susceptibility test protocol. American Society for Microbiology. https://asm.org/getattachment/2594ce26-bd44-47f6-8287-0657aa9185ad/kirby-bauer-disk-diffusion-susceptibility-testprotocol-pdf.pdf (accessed 10 October 2025).
Husna A, Rahman M M, Badruzzaman A T M, Sikder M H, Islam M R, Rahman M T, Alam J and Ashour H M. (2023). Extended-spectrum β-lactamases (ESBL): Challenges and opportunities. Biomedicines 11(11): 2937. https://doi.org/10.3390/biomedicines11112937
Kadeřábková N, Mahmood A J S, and Mavridou D A I. (2024). Antibiotic susceptibility testing using minimum inhibitory concentration (MIC) assays. NPJ Antimicrobial and Resistance 2(1): 37. https://doi.org/10.1038/s44259-024-00051-6
Kor S B, Choo Q C and Chew C H. (2013). New integron gene arrays from multi-resistant clinical isolates of members of the Enterobacteriaceae and Pseudomonas aeruginosa from hospitals in Malaysia. Journal of Medical Microbiology 62(3): 412–420. https://doi.org/10.1099/jmm.0.053645-0
Liofilchem. (2025). Antibiotic disc interpretative criteria and quality control. https://www.liofilchem.com/images/prodotti-evidenza/antibiotic-disc/disc_interpretative_table.pdf (accessed 10 October 2025).
Magiorakos A P, Srinivasan A, Carey R B, Carmeli Y, Falagas M E, Giske C G, Harbarth S, et al. (2012). Multidrug-resistant, extensively drug-resistant and pandrug-resistant bacteria: An international expert proposal for interim standard definitions for acquired resistance. Clinical Microbiology and Infection 18(3): 268–281. https://doi.org/10.1111/j.1469-0691.2011.03570.x
Patel P and Preuss C. (2024). Cephalosporins. Treasure Island (FL): StatPearls Publishing. https://www.ncbi.nlm.nih.gov/books/NBK551517/ (accessed 10 October 2025).
Perez-Bou L, Gonzalez-Martinez A, Cabrera J J, Juarez-Jimenez B, Rodelas B, Gonzalez-Lopez J and Correa-Galeote D. (2024). Design and validation of primer sets for the detection and quantification of antibiotic resistance genes in environmental samples by quantitative PCR. Microbial Ecology 87(1): 71. https://doi.org/10.1007/s00248-024-02385-0
Projan S J, Brown-Skrobot S, Schlievert P M, Vandenesch F and Richard P N. (1994). Glycerol monolaurate inhibits the production of beta-lactamase, toxic shock toxin-1, and other staphylococcal exoproteins by interfering with signal transduction. Journal of Bacteriology 176(14): 4204–4209. https://doi.org/10.1128/jb.176.14.4204-4209.1994
Rahman H, Sitompul J P and Tjokrodiningrat S. (2022). The composition of fatty acids in several vegetable oils from Indonesia. Biodiversitas 23: 2167–2176. https://doi.org/10.13057/biodiv/d230452
Sawale M, Singh A, Gutierrez V, Bala S, Murguia-Peniche T, Ozadali F, Benyathiar P and Mishra D. (2024). Antimicrobial effect of lactoferrin and glycerol monolaurate on selected bacteria associated with newborn infections. Food Control 168: 110882. https://doi.org/10.1016/j.foodcont.2024.110882
Schlievert P M and Peterson M L. (2012). Glycerol monolaurate antibacterial activity in broth and biofilm cultures. Edited by Gunnar F. Kaufmann. PLoS ONE 7(7): e40350. https://doi.org/10.1371/journal.pone.0040350
Then R. (2007). Beta-lactamase. In S J Enna and D B Bylund (eds.). xPharm: The comprehensive pharmacology reference. New York: Elsevier, 1–9. https://www.sciencedirect.com/science/article/abs/pii/B9780080552323605720 (accessed 10 October 2025).