Inhibition of Staphylococcus aureus by Oleuropein Is Mediated by Hydrogen Peroxide (original) (raw)
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Individual and Combined Antimicrobial Activity of Oleuropein and Chemical Sanitizers
Journal of Food Chemistry and Nanotechnology, 2016
In this study, the minimum inhibitory concentration (MIC) of oleuropein (OLE), a phenolic compound extracted from Oliveira leaves, alone or in combination with commercial sanitizers, was determined for Listeria monocytogenes (ATCC 7644), Staphylococcus aureus (ATCC 25923) and Escherichia coli (ATCC 25922). MIC values were determined using individual suspensions containing nearly 10 8 cells/mL of each bacterial species treated with serial dilutions of OLE (0.4 mg/mL) and commercially available solutions of Peracetic acid (PAA, 2.0%), Benzalkonium chloride (BC, 1.0%), Chlorhexidine digluconate (CD, 2.0%), Sodium hypochlorite (SH, 2.0%) and Hydrogen peroxide (HP, 3.0%). OLE had low inhibitory activity (0.2 mg/mL). As expected commercial sanitizers showed high bactericidal activity according to MIC values. However, the association of OLE with commercial sanitizers increased their bactericidal effect, especially for CD, which combination with OLE resulted in approximately 60-fold reduction in the MIC values for S. aureus and L. monocytogenes. OLE and BC also led to nearly 30-fold or 10-fold reductions of MIC values for S. aureus and L. monocytogenes, respectively. The combination of PAA and OLE reduced the MIC values for E. coli and S. aureus by 10-fold, with little effect on L. monocytogenes. Results of this preliminary study indicate that OLE has the potential to enhance the bactericidal effect of commercial sanitizers, especially against L. monocytogenes and S. aureus. Further studies are necessary to understand the mechanisms of action of these combinations.
Hydrogen peroxide as a potent bacteriostatic antibiotic: Implications for host defense
Free Radical Biology and Medicine, 1995
Host defense against bacterial pathogens in higher organisms is mediated in part by the generation of reactive oxygen species (ROS) by PMN. In this study, we determined the following effects of exposure of constant concentrations of H202 on E. coli in a culture continuously monitored for H202 concentration, numbers, and viabilities of cells: (l) E. coli growth rates monitored for 1 h were profoundly affected by concentrations of H202, between 25-50 #M. (2) Complete bacteriostasis was observed at 100/~M. (3) Significant cell killing was not observed until the concentration of H202 was greater than 500 #M. (4) Bacteriostatic (25-50 #M) concentrations of H202 appeared not to be toxic to human skin fibroblasts for a 2-h exposure. (4) Bacteriostasis by H202 could not be explained by metabolic inhibition, because intracellular ATP levels were not compromised at bacteriostatic doses of H202. (5) Measurements of H202 concentrations in subcutaneous abscess fluid infected with both E. coli and S. aureus indicated prevailing concentrations of the oxidant consistent with a proposed role of H202 in host defense.
Journal of Bacteriology, 2014
Glyceraldehyde-3-phosphate dehydrogenase (GAPDH) from human pathogens Staphylococcus aureus and Pseudomonas aeruginosa can be readily inhibited by reactive oxygen species (ROS)-mediated direct oxidation of their catalytic active cysteines. Because of the rapid degradation of H 2 O 2 by bacterial catalase, only steady-state but not one-dose treatment with H 2 O 2 rapidly induces glycolysis and the pentose phosphate pathway (PPP). We conducted transcriptome sequencing (RNA-seq) analyses to globally profile the bacterial transcriptomes in response to a steady level of H 2 O 2 , which revealed profound transcriptional changes, including the induced expression of glycolytic genes in both bacteria. Our results revealed that the inactivation of GAPDH by H 2 O 2 induces metabolic levels of glycolysis and the PPP; the elevated levels of fructose 1,6-biphosphate (FBP) and 2-keto-3-deoxy-6-phosphogluconate (KDPG) lead to dissociation of their corresponding glycolytic repressors (GapR and HexR,...
Integrative Food, Nutrition and Metabolism, 2016
suspended in Brain Heart Infusion broth (BHI) (Merck, Germany) with 15% (v/v) glycerol (Synth, Brazil) to form stock suspensions of each strain and were stored at-80°C. The bacterial working suspensions were prepared by adding 15 µL of each stock suspension to 5 mL of BHI. After incubation at 30°C for 24 h, the tubes were vortexed and diluted to 0.5 on the McFarland scale (nearly 10 8 cells mL-1). Sensitivity of bacterial cells to oleuropein and peracetic acid OLE (purity: >80%) was purchased from Sigma-Aldrich (Saint Louis, MO) and diluted in sterilized water to prepare a working solution containing 4.0 mg mL-1 , as described by Dominciano et al. [10]. A commercially available solution of PAA (Dinamica, São Paulo, Brazil) containing 2.0% (v/v) was used in the experiment, which is the minimum PAA concentration commonly used for disinfection of equipment and utensils in the food industry [5]. The sensitivity of E. coli and S. aureus cells to OLE and PAA, alone or in combination, was assessed by agar disk diffusion using a modification of the National Committee for Clinical Laboratory Standards [11]. The bacterial working suspension was applied to Petri dish plates containing Mueller-Hinton Agar (Sigma-Aldrich®) in triplicate. Sterilized filter paper discs (6 mm) were soaked in individual solutions containing OLE (4.0 mg mL-1), PAA (2.0%, v/v), or OLE + PAA (4.0 mg mL-1 , and 2.0%, v/v) for 1 min. The disks were placed in the center of the prepared
The Journal of Infectious Diseases, 2002
Staphylococcus aureus is resistant to a-defensins, antimicrobial peptides that play an important role in oxygen-independent killing of human neutrophils. The dlt operon mediates D-alanine incorporation into teichoic acids in the staphylococcal cell envelope and is a determinant of defensin resistance. By using S. aureus wild-type (WT) and Dlt Ϫ bacteria, the relative contributions of oxygen-dependent and-independent antimicrobial phagocyte components were analyzed. The Dlt Ϫ strain was efficiently killed by human neutrophils even in the absence of a functional respiratory burst, whereas the killing of the WT organism was strongly diminished when the respiratory burst was inhibited. Human monocytes, which do not produce defensins, inactivated the WT and Dlt Ϫ bacteria with similar efficiencies. In addition, mice injected with the Dlt Ϫ strain had significantly lower rates of sepsis and septic arthritis and fewer bacteria in the kidneys, compared with mice infected with the WT strain. Mucosal membranes and skin are efficient barriers against infections, in part because of the production of antimicrobial peptides, such as human b-defensin-2 (HBD-2), that contribute to protection against microbial pathogens (reviewed in [1-3]). Staphylococcus aureus, a major cause of community-and hospital-acquired infections, has evolved means to circumvent host defenses [4, 5]. S. aureus exhibits resistance to HBD-2 [6] and can invade epithelial and endothelial cells [7, 8], thereby allowing the pathogen to persist by "hiding" from phagocytes and antibiotics. Once bacteria infect the subepithelial tissues, polymorphonuclear leukocytes (PMNL) are recruited by the host to prevent further spread of the infection. Oxygen-dependent and-independent mechanisms are used to eliminate ingested bacteria [9]. The former strategy is mediated by toxic oxygen intermediates
Microbiology, 2006
The response of Staphylococcus aureus to hypochlorous acid (HOCl) exposure was investigated. HOCl challenges were performed on cultures interrupted in the exponential phase. Pretreatment with HOCl conferred resistance to hydrogen peroxide in a PerR-dependent manner. Derepression of the PerR regulon was observed at low HOCl concentration (survival >50 %), using several fusions of different stress promoters to lacZ reporter genes. At least four members of the PerR regulon (katA, mrgA, bcp and trxA) encoding proteins with antioxidant properties were strongly induced following exposure to various HOCl concentrations. A striking result was the link between the derepression of the PerR regulon and the decreased superoxide dismutase (SOD) activity following exposure to increased HOCl concentrations. The sodA mutant was more resistant than the wild-type and also had a higher level of 3-phosphoglycerate dehydrogenase (a measure of PerR regulon activity) without exposure to HOCl. Together,...
The synergistic effect of PDT and oxacillin on clinical isolates of Staphylococcus aureus
Lasers in surgery and medicine, 2018
Staphylococcus aureus is a major pathogen in clinical microbiology. It is known to cause infections at various body sites and can be life-threatening. The development of resistance to many well-established antibiotic treatments and the prevalence of methicillin-resistant S. aureus (MRAS) among hospital patients and the general community pose challenges in treating the pathogen. The antimicrobial effect of photodynamic therapy (PDT) has been a subject of study for a long time and can offer new strategies for dealing with resistant strains. In our study, we searched for a positive synergistic relationship between PDT and the standard antibiotics used to treat S. aureus and MRSA infections. The phototoxic profile of deuteroporphyrin (DP) in both resistant and susceptible clinical strains of S. aureus was determined by plating of treated and untreated broth cultures. Electron microscopy imaging was done to explore possible sites of damage and free-radical accumulation in the cells durin...
Infection and Immunity, 1991
Staphylococcus aureus is susceptible to killing by host-derived fatty acids. Studies were performed to test for a correlation between carotenoid production by S. aureus and protection against oleic acid. Oleic acid killing of cells grown in carotenoid expression medium was determined as the dosage of oleic acid in 2 M NaCl-2 mM EDTA that would kill 20% of the cells in 60 min at 37 degrees C (i.e., the 20% lethal dose). Compared with the wild-type strain (18Z), a carotenoid-deficient mutant strain (18Z-76) and strain 18Z grown in a medium that suppressed carotenoid production both showed increased sensitivity to oleic acid. Spontaneous revertants of strain 18Z-76 that regained the ability to produce carotenoids were as resistant to oleic acid as the wild-type strain. Oleic acid was shown by fluorescence polarization to decrease polarization values. Lower polarization values indicate a more-fluid membrane. To determine whether protection against oleic acid killing might depend on caro...