Evaluation of the antibacterial and modulatory activities of ethanolic excract of Calotropis procera (Aiton) W.T. Aiton against multiresistant bacterial strains

The objective of this study was to evaluate the antibacterial and modulatory activities of ethanolic extract of Calotropis procera (Aiton) W.T. Aiton against resistant species. By microdilution method, the minimum inhibitory concentration (MIC) of the extract and modulation of the subinhibitory concentration MIC/8 to norfloxacine, gentamicin and imipenem against Staphylococcus aureus, Escherichia coli and Pseudomonas aeruginosa. There was obtained 512 μg/mL to Pseudomonas aeruginosa. To Staphylococcus aureus, modulation showed synergism to norfloxacin and gentamicin, with imipenem against Pseudomonas aeruginosa and gentamicin against Escherichia coli. Based on these results, more studies are needed to test the antibacterial activity of the extract. El objetivo de este estudio fue evaluar la actividad antibacteriana y moduladora del extracto etanólico de Calotropis procera (Aiton) W.T. Aiton contra cepas multirresistentes de bacterias. Por el método de microdilución, fueron definidas la concentración inhibidora mínima (MIC) del extracto y la modulación con la concentración inhibidora CIM / 8 del extracto con norfloxacina, gentamicina e imipenem contra Staphylococcus aureus, Escherichia coli y Pseudomonas aeruginosa. Se obtuvo 512 μg/mL para Pseudomonas aeruginosa. Se descubrió sinergismo en el caso de Staphylococcus aureus, en la modulación con norfloxacina y gentamicina, mientras que con imipenem frente a Pseudomonas aeruginosa y con gentamicina para Escherichia coli. Con base en estos resultados, se necesitan más estudios para probar la actividad antibacteriana del extracto.

Enhancement of pyocyanin production by subinhibitory concentration of royal jelly in Pseudomonas aeruginosa

Background: Pseudomonas aeruginosa, a multidrug-resistant Gram-negative bacterium, produces pyocyanin, a virulence factor associated with antibiotic tolerance. High concentrations of royal jelly have an antibacterial effect, which may potentially overcome antibacterial resistance. However, in some cases, antibiotic tolerance can occur due to prolonged stress of low-dose antibacterial agents. This study aimed to investigate the effect of subinhibitory concentrations of royal jelly on bacterial growth, pyocyanin production, and biofilm formation of P. aeruginosa. Methods: Pseudomonas aeruginosa ATCC 10145 and clinical isolates were cultured in a royal jelly-containing medium to test the antibacterial activity. Pyocyanin production was observed by measuring the absorbance at 690 nm after 36 h culture and determined using extinction coefficient 4310 M-1 cm-1. Static microtiter plate biofilm assay performed to detect the biofilm formation, followed by scanning electron microscopy. Results: Royal jelly effectively inhibited the viability of both strains from a concentration of 25%. The highest production of pyocyanin was observed in the subinhibitory concentration group 6.25%, which gradually decreased along with the decrease of royal jelly concentration. Results of one-way ANOVA tests differed significantly in pyocyanin production of the two strains between the royal jelly groups. Tukey HSD test showed concentrations of 12.5%, 6.25%, and 3.125% significantly increased pyocyanin production of ATCC 10145, and the concentrations of 12.5% and 6.25% significantly increased production of the clinical isolates. Concentrations of 12.5% and 6.125% significantly induced biofilm formation of P. aeruginosa ATCC 10145, in line with the results of the SEM analysis. Conclusions: The royal jelly concentration of 25% or higher inhibits bacterial growth; however, the subinhibitory concentration increases pyocyanin production and biofilm formation in P. aeruginosa. It is advisable to determine the appropriate concentration of royal jelly to obtain beneficial virulence inhibiting activity.

Enhancement of pyocyanin production by subinhibitory concentration of royal jelly in Pseudomonas aeruginosa

Background: Pseudomonas aeruginosa, a multidrug-resistant Gram-negative bacterium, produces pyocyanin, a virulence factor associated with antibiotic tolerance. High concentrations of royal jelly have an antibacterial effect, which may potentially overcome antibacterial resistance. However, in some cases, antibiotic tolerance can occur due to prolonged stress of low-dose antibacterial agents. This study aimed to investigate the effect of subinhibitory concentrations of royal jelly on bacterial growth, pyocyanin production, and biofilm formation of P. aeruginosa. Methods: Pseudomonas aeruginosa ATCC 10145 and clinical isolates were cultured in a royal jelly-containing medium to test the antibacterial activity. Pyocyanin production was observed by measuring the absorbance at 690 nm after 36 h culture and determined using extinction coefficient 4310 M-1 cm-1. Static microtiter plate biofilm assay performed to detect the biofilm formation, followed by scanning electron microscopy. Results: Royal jelly effectively inhibited the viability of both strains from a concentration of 25%. The highest production of pyocyanin was observed in the subinhibitory concentration group 6.25%, which gradually decreased along with the decrease of royal jelly concentration. Results of one-way ANOVA tests differed significantly in pyocyanin production of the two strains between the royal jelly groups. Tukey HSD test showed concentrations of 12.5%, 6.25%, and 3.125% significantly increased pyocyanin production of ATCC 10145, and the concentrations of 12.5% and 6.25% significantly increased production of the clinical isolates. Concentrations of 12.5% and 6.125% significantly induced biofilm formation of P. aeruginosa ATCC 10145, in line with the results of the SEM analysis. Conclusions: The royal jelly concentration of 25% or higher inhibits bacterial growth; however, the subinhibitory concentration increases pyocyanin production and biofilm formation in P. aeruginosa. It is advisable to determine the appropriate concentration of royal jelly to obtain beneficial virulence inhibiting activity.

Enhancement of pyocyanin production by subinhibitory concentration of royal jelly in Pseudomonas aeruginosa

Background: Pseudomonas aeruginosa, a multidrug-resistant Gram-negative bacterium, produces pyocyanin, a virulence factor associated with antibiotic tolerance. High concentrations of royal jelly have an antibacterial effect, which may potentially overcome antibacterial resistance. However, in some cases, antibiotic tolerance can occur due to prolonged stress of low-dose antibacterial agents. This study aimed to investigate the effect of subinhibitory concentrations of royal jelly on bacterial growth, pyocyanin production, and biofilm formation of P. aeruginosa. Methods: Pseudomonas aeruginosa ATCC 10145 and clinical isolates were cultured in a royal jelly-containing medium to test the antibacterial activity. Pyocyanin production was observed by measuring the absorbance at 690 nm after 36 h culture and determined using extinction coefficient 4310 M-1 cm-1. Static microtiter plate biofilm assay performed to detect the biofilm formation, followed by scanning electron microscopy. Results: Royal jelly effectively inhibited the viability of both strains from a concentration of 25%. The highest production of pyocyanin was observed in the subinhibitory concentration group 6.25%, which gradually decreased along with the decrease of royal jelly concentration. Results of one-way ANOVA tests differed significantly in pyocyanin production of the two strains between the royal jelly groups. Tukey HSD test showed concentrations of 12.5%, 6.25%, and 3.125% significantly increased pyocyanin production of ATCC 10145, and the concentrations of 12.5% and 6.25% significantly increased production of the clinical isolates. Concentrations of 12.5% and 6.125% significantly induced biofilm formation of P. aeruginosa ATCC 10145, in line with the results of the SEM analysis. Conclusions: Royal jelly concentrations of 25% or higher can inhibit bacterial growth; however, subinhibitory concentrations could increase pyocyanin production and biofilm formation in P. aeruginosa. It is advisable to determine the appropriate concentration of royal jelly to obtain beneficial virulence inhibiting activity.

Antibiofilm Activity of Small-Molecule ZY-214-4 Against Staphylococcus aureus

Staphylococcus aureus is the most important pathogenic bacteria in humans. As the resistance of S. aureus to existing antibiotics is increasing, there is an urgent need for new anti-infective drugs. S. aureus biofilms cause persistent infections and resist complete eradication with antibiotic therapy. The present study investigated the inhibitory effect of the novel small-molecule ZY-214-4 (C19H11BrNO4) on S. aureus biofilm formation. At a subinhibitory concentration (4 μg/ml), ZY-214-4 had no effect on the growth of S. aureus strains and also showed no cytotoxicity in human normal bronchial epithelial cells (Bease-2B). The results of a semi-quantitative biofilm test showed that ZY-214-4 prevented S. aureus biofilm formation, which was confirmed by scanning electron microscopy and confocal laser scanning microscopy. ZY-214-4 significantly suppressed the production of polysaccharide intercellular adhesion and prevented cell aggregation, and also inhibited the mRNA expression of icaA and other biofilm-related genes (eno, clfA/B, fnbB, fib, ebpS, psmα, and psmβ) in clinical S. aureus isolates. Thus, at a subinhibitory concentration, ZY-214-4 inhibits biofilm formation by preventing cell aggregation, highlighting its clinical potential for preventing or treating S. aureus infections.