Antimicrobial and antibiofilm activities of paeoniflorin against carbapenem-resistant Klebsiella pneumoniae.

To evaluate the antimicrobial effect of paeoniflorin against carbapenem-resistant Klebsiella pneumoniae (CRKP). Minimum inhibitory concentration (MIC) of paeoniflorin against CRKP was determined by agar dilution method. Changes in intracellular ATP concentration, intracellular pH (pHin), cell membrane potential and membrane integrity were investigated to assess the influence of paeoniflorin on cell membrane damage. Additionally, alterations in cell structure of CRKP cells and cell damage within biofilms were examined. The results indicated that paeoniflorin was effective against CRKP at MIC of 1·2 mg ml-1 . Paeoniflorin destroyed the integrity of CRKP cell membrane, as was confirmed by decrease of intracellular ATP, pHin, membrane potential, as well as distinctive alteration in cell morphology, resulting in leakage of CRKP intracellular components. Moreover, paeoniflorin displayed a markedly inhibitory influence on biofilm formation of CRKP and inactivated CRKP cells within biofilms. Paeoniflorin shows promise as an effective antibiotic against CRKP with the potential to be an alternative therapeutic agent. This study provides information about the potential use of paeoniflorin to reduce the infection of CRKP in clinical practice and food production.

Qian W ，Zhang J ，Wang W ，Wang T ，Liu M ，Yang M ，Sun Z ，Li X ，Li Y ... -  《-》

Antimicrobial activity of eugenol against carbapenem-resistant Klebsiella pneumoniae and its effect on biofilms.

A preliminary study found that eugenol expressed an antibacterial activity against Klebsiella pneumoniae. However, the mechanism of action of eugenol against K. pneumoniae still remains unexplored. The aim of this study was to gain further insight into the antibacterial effect of eugenol against carbapenem-resistant Klebsiella pneumoniae (CRKP) and possible mode of action. Here, minimum inhibitory concentration (MIC) of eugenol against CRKP strains was determined using the agar dilution method. Moreover, variations in intracellular ATP concentration, intracellular pH (pHin), membrane potential and membrane integrity were measured to evaluate the effect of eugenol on cell membrane. Besides, changes in cell structure and biofilm formation of CRKP as well as biofilm-associated cell damage were determined using field emission scanning electron microscope (FESEM), transmission electron microscope (TEM) and confocal laser scanning microscopy (CLSM). Finally, gene expression of biofilm-related biosynthesis was investigated. The results showed that MICs of eugenol against four tested CRKP were 0.2 mg/mL. Eugenol damaged the cell membrane of CRKP, as evidenced by decreased intracellular ATP concentration, reduced pHin and cell membrane hyperpolarization, coupled with enhanced membrane permeability. Furthermore, eugenol compromised cell structure and induced loss of intracellular components of CRKP. Additionally, eugenol inhibited biofilm formation and inactivated biofilm CRKP cells. Finally, eugenol presented strong inhibitory effects on biofilm formation and biofilm-associated gene expression, and inactivated CRKP cells growing in biofilms. These findings suggest that eugenol exhibits antimicrobial effect against CRKP strains and could be potentially used to control CRKP-related infections.

Qian W ，Sun Z ，Wang T ，Yang M ，Liu M ，Zhang J ，Li Y ... -  《-》

Antimicrobial and antibiofilm activities of ursolic acid against carbapenem-resistant Klebsiella pneumoniae.

Qian W ，Wang W ，Zhang J ，Wang T ，Liu M ，Yang M ，Sun Z ，Li X ，Li Y ... -  《-》

A Study of the Virulence Traits of Carbapenem-Resistant Klebsiella pneumoniae Isolates in a Galleria mellonella Model.

Khalil MAF ，Hager R ，Abd-El Reheem F ，Mahmoud EE ，Samir T ，Moawad SS ，Hefzy EM ... -  《-》

In-vitro antibacterial activity and mechanism of Monarda didyma essential oils against Carbapenem-resistant Klebsiella pneumoniae.

To fight the global epidemic of drug-resistant bacteria, essential oils have gained increasing attention as a new source of antibiotics. The antimicrobial activity of Monarda didyma essential oils (MDEO) for the Carbapenem-resistant Klebsiella pneumoniae (CRKP) strains were determined by agar disc diffusion assay and broth microdilution assay. To further understand MDEO efficacy, a time-growth curve was performed. The biofilm formation of CRKP were determined by crystalline violet staining method, additionally, changes in intracellular Adenosine triphosphate (ATP), protein, Alkaline phosphatase (AKP) activities, and membrane integrity were investigated to assess the influence of MDEO on cell membrane damage. Finally, the activities of key enzymes in the tricarboxylic acid (TCA) pathways and pentose phosphate (PPP) pathways were examined to determine the effect of MDEO on the respiratory metabolism of CRKP. This study presents the antibacterial mechanism of MDEO against CRKP with a minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of 1.25 mg/ml. To understand MDEO efficacy, a time-kill kinetics approach was performed. The bactericidal effect of MDEO was evident at 2 h compared to the control at its MIC and 2MIC. Surface electron microscopic and ATP assay studies provided evidence for the multi-target action of MDEO against CRKP. MDEO could inhibit CRKP biofilm formation. MDEO could also cause irreversible damage to the CRKP cell membrane, resulting in the leakage of biological macromolecules (protein, ATP) and the reduction of intracellular enzymes (AKP) activities. Finally, MDEO affected the pathways of respiratory metabolism, such as PPP and TCA pathways. MDEO could reduce the activity of key enzymes (Glucose-6-phosphate dehydrogenase, citrate synthase, isocitrate dehydrogenase, and α-ketoglutarate dehydrogenase) in the PPP and TCA pathways to exert its biological effects against CRKP. These results suggest MDEO can exert inhibitory effects on CRKP, and potential mechanisms of action including inhibition of biofilm formation, damage of cell membrane structure and inhibition of energy metabolism.

Chen Y ，Zhao J ，Liu C ，Wu D ，Wang X ... -  《BMC MICROBIOLOGY》