Combinatorial effect analysis of Peppermint (Mentha x piperita L. Carl) essential oil and meropenem against plasmid-mediated resistant E. coli

Chew-Li Moo; Shun-Kai Yang; Polly Soo-Xi Yap; Thiba Krishnan; Khatijah Yusoff; Kok-Gan Chan; Swee-Hua Erin Lim; Kok-Song Lai

Chew-Li Moo Department of Cell and Molecular Biology, Faculty of Biotechnology and Biomolecular Sciences, Universiti Putra Malaysia, 43400 Serdang, Selangor, Malaysia
Shun-Kai Yang Department of Cell and Molecular Biology, Faculty of Biotechnology and Biomolecular Sciences, Universiti Putra Malaysia, 43400 Serdang, Selangor, Malaysia
Polly Soo-Xi Yap School of Postgraduate Studies and Research, International Medical University, No. 126, Jalan Jalil Perkasa 19, Bukit Jalil, 57000 Kuala Lumpur, Malaysia
Thiba Krishnan Division of Genetics and Molecular Biology, Institute of Biological Sciences, Faculty of Science, University of Malaya, 50603 Kuala Lumpur, Malaysia
Khatijah Yusoff Department of Microbiology, Faculty of Biotechnology and Biomolecular Sciences, Universiti Putra Malaysia, 43400 Serdang, Selangor, Malaysia
Kok-Gan Chan Department of Microbiology, Faculty of Biotechnology and Biomolecular Sciences, Universiti Putra Malaysia, 43400 Serdang, Selangor, Malaysia
Swee-Hua Erin Lim Centre for Research Excellence, Perdana University, MAEPS Building, Serdang, Selangor, Malaysia
Kok-Song Lai Health Sciences Division, Abu Dhabi Women’s College, Higher Colleges of Technology, 41012 Abu Dhabi, United Arab Emirates

Abstract

This study was carried out to investigate the bactericidal mechanism of peppermint essential oil (PEO) when PEO (1 % v/v) used individually and PEO (1 % v/v) in combination with meropenem (0.5 µg/mL) against multidrug resistant Escherichia coli. Chemical composition of PEO were identified via GC-MS, followed by time-kill analysis which was performed to evaluate the antibacterial activities of PEO and meropenem. In order to assess the ability of PEO in disrupting the bacterial membrane, zeta potential measurement, outer membrane permeability test and scanning electron microscopy were performed. Next, anti-quorum sensing assay was performed to assess the ability of PEO in quorum sensing inhibition. A complete killing activity was observed within five minutes of treatment with PEO and meropenem at sub-lethal concentrations. In addition, the zeta potential measurement and outer membrane permeability test performed indicated increase in the membrane permeability and membrane disruption which can be observed in the scanning electron micrograph. Furthermore, significant decrease in the light production of E. coli pSB1075 treated with PEO indicates the presence of quorum sensing inhibitors within PEO. The findings suggested that PEO possesses the capability to disrupt the bacterial outer membrane, thus increasing membrane permeability, in addition to possible inhibition of bacterial quorum sensing ability in multidrug resistant E. coli, elucidation of the actual mechanism will, greatly assist the mitigation of reversal of antibiotic resistance.

Keywords: Escherichia coli; essential oil; membrane permeability; Mentha x piperita L. Carl; quorum sensing; combinatorial effect.