In vitro bactericidal activity of a carbohydrate polymer with zinc oxide for the treatment of chronic wounds

Introduction. Biological adhesives and effective topical therapeutic agents that improve wound healing are urgently required for the treatment of chronic ulcers. A biodegradable adhesive based on a carbohydrate polymer with zinc oxide (CPZO) was shown to possess anti-inflammatory activity and enhance wound healing, but its bactericidal activity was unknown.Aim. To investigate the bactericidal activity of CPZO against bacteria commonly present as infectious agents in chronic wounds.Methodology. We examined the bactericidal activity of CPZO against three biofilm-producing bacteria (Staphylococcus aureus, Escherichia coli and Pseudomonas aeruginosa) through three strategies: bacterial suspension, biofilm disruption and in vitro wound biofilm model.Results. In suspension cultures, CPZO had direct, potent bactericidal action against S. aureus within 24 h, whereas E. coli took 7 days to be eliminated. By contrast, P. aeruginosa survived up to 14 days with CPZO. CPZO had biofilm disruption activity against clinical isolates of S. aureus in the anti-biofilm test. Finally, in the in vitro wound biofilm model, CPZO dramatically reduced the bacterial viability of S. aureus and P. aeruginosa.Conclusions. Together with its previously shown anti-inflammatory properties, the bactericidal activity of CPZO gives it the potential to be a first-line therapeutic option for chronic various ulcers and, possibly, other chronic ulcers, preventing or controlling microbial infections, and leading to the healing of such complicated chronic ulcers.

Association of Listeria monocytogenes LIPI-1 and LIPI-3 marker llsX with invasiveness

Listeria monocytogenes is an opportunistic pathogen that is widely distributed in the environment. The evolution of its genome has exhibited differences in virulence among strains of the same species. Listeria monocytogenes LIPI-3 (Listeria Pathogenicity Island 3) and LIPI-1 (Listeria Pathogenicity Island 1) are considered responsible for the increased virulence in some strains. The aim of this study was to detect LIPI-1 genes and the llsX gene belonging to LIPI-3 in invasive strains of L. monocytogenes and to establish whether there is a relationship among the invasiveness, presence of the llsX and LIPI-1 genes, and the source of the strains. The results showed that 70% of the strains were invasive, and all these strains except one possessed LIPI-1, which suggests that although there is a correlation between LIPI-1 and invasiveness, the independent mechanisms of LIPI-1 may contribute to invasiveness. In contrast, 35% of the total strains were positive for llsX and were invasive; thus, the results revealed that there is a strong association between llsX and the invasiveness of L. monocytogenes in HEp-2 cells (HeLa contaminant/epithelial in origin). In addition, there is no other association with any other variable in this study. Moreover, the authors found that LIPI-1 and llsX are more frequently found in fresh than in frozen vegetables. Together, the findings provide an approximation for the better understanding of Listeriolysin S (LLS) and its role in the pathogenesis of L. monocytogenes, and a possible relation between virulence factors and food-storage temperature.