Lavender essential oil induces oxidative stress which modifies the bacterial membrane permeability of carbapenemase producing Klebsiella pneumoniae

Abstract

Misuse of antibiotics in the clinical and agricultural sectors has caused the emergence of multidrugresistant (MDR) Klebsiella pneumoniae which contributes a threat to human health. in this study, we assessed the feasibility of lavender essential oil (LVo) as an antimicrobial agent in combinatory therapy with meropenem in suppressing the growth of carbapenemase-producing K. pneumoniae (Kpc-Kp). Synergistic interactions between LVO and meropenem were detected, which significantly reduce the inhibitory concentration of both LVO and meropenem by 15 and 4-fold respectively. Comparative proteomic profiling identified a disruption in the bacterial membrane via oxidative stress that was indicated by loss of membrane and cytoplasmic proteins and the upregulation of oxidative regulators. As a proof of concept, zeta potential measurements showed a change in cell surface charge while outer membrane permeability measurement indicated an increase in membrane permeability following exposure to LVO. This was indicative of a disrupted outer membrane. Ethidium bromide influx/efflux assays demonstrated no significant efflux pump inhibition by LVO, and scanning electron microscopy revealed irregularities on the cell surface after exposure to LVo. oxidative stress was also detected with increased level of RoS and lipid peroxidation in LVo-treated cells. in conclusion, our data suggest that LVo induced oxidative stress in K. pneumoniae which oxidizes the outer membrane, enabling the influx of generated ROS, LVO and meropenem into the bacterial cells, causing damage to the cells and eventually death. Klebsiella pneumoniae, a Gram-negative rod-shaped bacterium is one of the leading causes of hospital acquired infections, and is especially implicated in bacterial pneumonia 1,2. Misuse of antibiotics in the clinical and agricultural sectors has brought about the emergence of multidrug-resistant (MDR) K. pneumoniae, which is a threat to human health, especially in vulnerable groups such as neonates, the elderly and the immunocompromised 3,4. Carbapenems are now considered as the last resort antibiotics for treating severe MDR K. pneumoniae infections. However, resistance towards carbapenems was soon documented in K. pneumoniae due to increased reliance upon this line of antibiotics 5,6. Carbapenem-resistant K. pneumoniae produces carbapenemase, the most evolved β-lactamase currently in evidence, which can inactivate almost all classes of β-lactam antibiotics 7,8. Other antibiotic resistance mechanisms such as the overproduction of class C beta-lactamases, expression of the MDR efflux pump or an ESBL coupled with bacterial membrane permeability defects are sufficient to confer a carbapenem resistance phenotype to K. pneumonia 9-11. It has been reported that certain isolated carbapenem-resistant K. pneumoniae overexpress AcrAB pumps which remove a variety of antibiotics that penetrate the bacterial cell wall and membranes 12,13. Another study confirmed reduction in expression of porin proteins which reduces

Incubation with a Complex Orange Essential Oil Leads to Evolved Mutants with Increased Resistance and Tolerance

“…Evolved strains with increased resistance and tolerance to carvacrol also showed mutations in transcriptional regulators induced by oxidative stress, such as soxR and yfhP , in E. coli [ 30 ] and S. enterica [ 10 ]. Oxidative stress was also induced by treatment with complex EO in Klebsiella pneumoniae [ 47 ]. These results highlight the relevance of oxidative stress in the cell response to natural antimicrobials.…”

“…According to Meades, et al [ 52 ], cinnamon EO inhibits the carboxyltransferase subunit of E. coli , which partially explains that EO’s antibacterial activity. Moreover, as is well known, cell membranes are the first barrier and one of the main structures affected by natural antimicrobials, which alter their permeability and disrupt their integrity [ 35 , 47 ]. It is likely that the mutation of accA could result in improved cell membrane formation and/or repair in presence of OEO.…”

An Overview of the Potential Therapeutic Applications of Essential Oils

“…These proteins that were lost play a role in energy generation; losing these proteins may disrupt the bacterial cell membrane and subsequent killing of the bacteria [ 75 ]. Moreover, the lavender EO (LVO) has been shown to cause oxidative stress to bacteria by oxidizing the outer membrane of the bacteria [ 120 , 121 , 122 ]. In fact, LVO and meropenem, in addition with reactive oxygen species (ROS), have resulted in bacterial membrane disruption.…”

Middle Eastern Plant Extracts: An Alternative to Modern Medicine Problems

“…Hence, it is necessary to look into alternative solutions, such as natural products, for example, plant extracts, to overcome impending threats in the medical field [11,12]. It has been widely reported that plant extracts such as essential oils contain various bioactive compounds which are responsible for bioactivities, such as antimicrobial, anticancer, and anti-inflammatory agents [6,[12][13][14][15]. As nature is rich with different plants, researchers have focused their attention towards plant extracts as an alternative to synthetic drugs to be applied in the clinical setting [16].…”