RETRACTED: In Vitro Antibacterial Activity and Mechanism of Vanillic Acid against Carbapenem-Resistant Enterobacter cloacae

Abstract

Vanillic acid (VA) is a flavoring agent found in edible plants and fruits. Few recent studies exhibited robust antibacterial activity of VA against several pathogen microorganisms. However, little was reported about the effect of VA on carbapenem-resistant Enterobacter cloacae (CREC). The purpose of the current study was to assess in vitro antimicrobial and antibiofilm activities of VA against CREC. Here, minimum inhibitory concentrations (MIC) of VA against CREC was determined via gradient diffusion method. Furthermore, the antibacterial mode of VA against CREC was elucidated by measuring changes in intracellular adenosine triphosphate (ATP) concentration, intracellular pH (pHin), cell membrane potential and membrane integrity. In addition, antibiofilm formation of VA was measured by crystal violet assay and visualized with field emission scanning electron microscopy (FESEM) and confocal laser scanning microscopy (CLSM). The results showed that MIC of VA against E. cloacae was 600 μg/mL. VA was capable of inhibiting the growth of CREC and destroying the cell membrane integrity of CREC, as confirmed by the decrease of intracellular ATP concentration, pHin and membrane potential as well as distinctive variation in cellular morphology. Moreover, crystal violet staining, FESEM and CLSM results indicated that VA displayed robust inhibitory effects on biofilm formation of CREC and inactivated biofilm-related CREC cells. These findings revealed that VA exhibits potent antibacterial activity against CREC, and thus has potential to be exploited as a natural preservative to control the CREC associated infections.

Health Promoting Properties of Cereal Vinegars

“…Gallic acid, catechin, and vanillic acid are the major phenolic compounds found in cereal vinegars [ 17 ]. The antimicrobial potential of these compounds against various pathogens, such as E. coli , Staphylococcus aureus , Pseudomonas aeruginosa , Enterobacter spp., Listeria spp., Mannheimia haemolytica , Pasteurella multocida , etc., has been demonstrated in several studies [ 74 , 75 , 76 , 77 , 78 , 79 ].…”

RETRACTED: Qian et al. In Vitro Antibacterial Activity and Mechanism of Vanillic Acid against Carbapenem-Resistant Enterobacter cloacae. Antibiotics 2019, 8, 220

“…The Editor-in-Chief has checked the case and communicated with the authors. The decision to retract has been taken in agreement with the authors of the paper [1]. The Antibiotics Editorial Office and authors apologize to the readers of Antibiotics for any inconvenience caused.…”

“…The authors have been made aware that two figures were published in two papers: Figure 5A in paper [1] is duplicated as Figure 3D in published paper [2], and Figure 3A in paper [1] is duplicated as Figure 3A in published paper [2]. The authors state this was due to carelessness.…”

“…In order to preserve academic integrity, the Antibiotics Editorial Office has taken the decision to retract the paper with the consent of the authors. The authors assert that the findings, that vanillic acid exerted a significant antibacterial activity against carbapenem-resistant Enterobacter cloacae (CREC), are nevertheless reliable [1].…”

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