Avaliação in-vitro da atividade antimicrobiana e da propriedade antiaderente do xilitol

Abstract

Recent researches show that xylitol, besides being used as a food ingredient, has many clinical applications, being used to treat diabetes, renal and parenteral lesions, as well as to prevent otitis media, caries, lung infections and osteoporosis. In the scientific literature, there are some reports on the anti-adherent action of xylitol on many bacteria. Currently, with the emergence of microorganisms resistant to conventional antibiotics, research for new strategies is necessary, aiming at preventing and/or treating diseases caused by the presence of such pathogens. A very promising approach is based on the awareness of the adherence of microorganisms to several surfaces, both in the host (in vivo) and in medical-hospital materials, and of the mechanisms which may prevent such colonization. The present study aimed at evaluating the antimicrobial activity and the anti-adherent property of xylitol on the bacterial strains Escherichia coli (ATCC 8739), clinical Escherichia coli (EPEC), clinical Salmonella enterica serotype Typhimurium, Shigella flexneri (ATCC 12022), clinical Shigella flexneri and Pseudomonas aeruginosa (ATCC 9027). The test of antimicrobial activity was realized to determinate a minimum inhibitory concentration (MIC) and the adhesion test were performed, according to which the parameters regarding growth in the culture medium, number of colony-forming units (CFUs) released and evaluation of slides using scanning electron microscopy (SEM) were analyzed. It was found that 0.5%, 2.5% and 5.0% concentrations of xylitol do not have antimicrobial activity on the strains tested. However, the inhibition of adherence was demonstrated both by counting the released bacilli and by SEM microphotographs. For 0.5%, 2.5% and 5.0% concentrations of xylitol, CFUs were released, respectively of 89 ± 6; 187 ± 12 and 257 ± 30 E.coli ATCC 8739 bacilli; 198 ± 28; 282 ± 20 and 311 ± 30 clinical E.coli – EPEC bacilli ; 65 ± 4; 23 ± 2 and 31 ± 1 clinical S. enterica sorotipo Typhimurium bacilli ; 131 ± 3; 120 ± 6 and 58 ± 6 S. flexneri ATCC 12022 bacilli; 779 ± 15; 146 ± 2 and 56 ± 6 clinical S. flexneri bacilli; 2259 ± 130; 2990 ± 130 and 5330 ± 0 P. aeruginosa ATCC 9027 bacilli. For all the strains tested, the results obtained show that the inhibition of microbial adhesion, observed in slides treated with xylitol, is probably the mechanism of action of this compound. This study gives xylitol a greater added value, making it an appropriate biomolecule to be used as adjuvant therapeutic for the prevention and/or treatment of a series of recurrent infections.