The impact of ethanol extract of propolis on biofilm forming by Proteus Mirabilis strains isolated from chronic wounds infections.

Alcoholic propolis extracts may be used to eliminate microbes in mucous membranes and skin inflammations and in wound infections. The aim of this study was an assessment of the ethanol extract of propolis (EEP) activity against biofilm formation by P. mirabilis. Six clinical strains of P. mirabilis isolated from patients with chronic wound infection, and one reference strain of P. mirabilis ATCC 29906 were used. Biofilm was formed in 96-well plate. In order to evaluate the effect of EEP at a concentration range of 1.56-100 mg/mL on the forming and mature biofilm, P. mirabilis cells were released by sonication. In this study the effectiveness of 25-100 mg/mL of EEP on the forming P. mirabilis biofilm and concentrations of 25-50 mg/mL of EEP on formed biofilm has been demonstrated. Our results suggest the possibility of using the EEP in treatment of chronic wound infection caused by P. mirabilis.

Inhibition of development, swarming differentiation and virulence factors in Proteus mirabilis by an extract of Lithrea molleoides and its active principle (Z,Z)-5-(trideca-4',7'-dienyl)-resorcinol.

Antibacterial activity of Lithrea molleoides extract against Proteus mirabilis has been previously reported by our group. In the present study, the compound (Z,Z)-5-(trideca-4',7'-dienyl)-resorcinol (1) was isolated as its responsible active principle. The effects of the compound obtained and of L. molleoides extract on P. mirabilis growth and virulence factors were evaluated. Compound 1 showed MIC and MBC values of 4000 µg/ml. It was found that the extract, at four times the MIC, produced complete killing of the uropathogen at 2h from the beginning of the experiment, while the alkylresorcinol, at four times the MIC, produced the same effect after 24 h. Hemolysis was adversely affected in treatments with both products at 8 µg/ml, while hemagglutination was not altered. The whole extract induced complete autoaggregation of P. mirabilis at 2000 µg/ml, while compound 1 at the same concentration did not show this property. Swarming motility was delayed in treatments with the extract and with 1 at 1000 and 8 µg/ml, respectively, at 8h from the beginning of the assay. Complete inhibition of the phenomenon was still observed after 24 h when compound 1 was added at 125 µg/ml. These findings offer the possibility of new classes of antimicrobial medicines to tackle infections caused by P. mirabilis.