Activity of maltodextrin and vancomycin against biofilm.

We aimed to assess the anti-biofilm activity of vancomycin, maltodextrin, and their combination against vancomycin resistant (VRSA) and vancomycin-susceptible (VSSA) strains based on an static model. Biofilms of 4 VSSA and 2 VRSA strains were grown in a 96-well static model. Vancomycin 2 mM, maltodextrin 10 mM, and both in combination were tested using tetrazolium salt (XTT), resazurin, and cfu/well counts. The efficacy of the antimicrobial solutions was expressed as the percentage reduction in metabolic activity with each method. Overall percentage reduction in the metabolic activity of VSSA was 79.3%, 34%, and 75.7% for vancomycin, maltodextrin, and their combination (p<0.001). Overall percentage reduction in metabolic activity of VRSA was 46.7%, 27.8%, and 34.6% for vancomycin, maltodextrin, and their combination (p>0.05). Maltodextrin did not improve the anti-biofilm efficacy of vancomycin in VSSA or in VRSA biofilms. XTT cannot replace cfu counts as a means of quantifying cell viability. Futures studies are needed to assess the synergistic effects of other non-antimicrobial molecules combined with vancomycin.