Effects of Calendula officinalis and Capsicum annum glycolic extracts on planktonic cells and biofilms of multidrug-resistant strains of Klebsiella pneumoniae and Pseudomonas aeruginosa.

Empirical knowledge of natural plant extracts is increasingly proving to be a promising field. The effect of Calendula officinalis L. (CO) and Capsicum annum (CA) glycolic extracts (GlExt) have potential that should be further developed in microbial tests. The effect of CO-GlExt and CA-GlExt was evaluated on eight multidrug-resistant clinical strains of Klebsiella pneumoniae and Pseudomonas aeruginosa, as well as collection strains for each bacterial. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of the extract were determined in comparison with 0.12% chlorhexidine. The tests were performed on single species biofilms, at 5 min and 24 h, using the MTT (3-(4,5-Dimethylthiazol-2-yl)-2,5-Diphenyltetrazolium Bromide) assay. The MIC and MBC of the extract ranged from 1.56 to 50 mg mL-1 for all strains evaluated. Analysis of the MTT assay revealed a strong antimicrobial potential of CA-GlExt, comparable to chlorhexidine. The findings suggest that CA-GlExt is effective against multidrug-resistant strains of K. pneumoniae and P. aeruginosa in planktonic state and biofilms.

Influence of Streptococcus mitis and Streptococcus sanguinis on virulence of Candida albicans: in vitro and in vivo studies.

The aim was to evaluate in vitro possible interactions, gene expression, and biofilm formation in species of Candida albicans, Streptococcus mitis, and Streptococcus sanguinis and their in vivo pathogenicity. The in vitro analysis evaluated the effects of S. mitis and S. sanguinis on C. albicans's biofilm formation by CFU count, filamentation capacity, and adhesion (ALS1, ALS3, HWP1) and transcriptional regulatory gene (BCR1, CPH1, EFG1) expression. In vivo studies evaluated the pathogenicity of the interaction of the microorganisms on Galleria mellonella, with analyses of the CFU per milliliter count and filamentation. In vitro results indicated that there was an observed decrease in CFU (79.4-71.5%) in multi-species biofilms. The interaction with S. mitis inhibited filamentation, which seems to increase its virulence factor with over-expression of genes ALS1, ALS3, and HWP1 as well the interaction with S. sanguinis as ALS3 and HWP1. S. mitis upregulated BRC1, CPH1, and EFG1. The histological images of in vivo study indicate an increase in the filamentation of C. albicans when in interaction with the other species. It was concluded that S. mitis interaction suggests increased virulence factors of C. albicans, with periods of lower virulence and proto-cooperation in the interaction with S. sanguinis.