Interference of morintides on some virulence determinants of selected bacterial pathogens

In this study, small antimicrobial peptides of <10 kDa (AMPs) from Moringa oleifera L were separated from crude protein by Ultra-15 Centrifugal filter devices and partially purified. The potency of morintides to interfere with the virulence determinants like biofilms, siderophores and elastase of selected bacteria was investigated by spectrophotometric method and Pseudomonas quinolone signal (PQS) by Thin-layer chromatography (TLC). GraphPad Prism 5.0 was used for statistical purpose. Assays were subjected to a two-way analysis of variance with Bonferroni as post-test. Shigella flexneri, Klebsiella pneumoniae, Escherichia coli and Staphylococcus aureus, showed a decrease in the attachment of cells to form biofilm in the presence of the morintides. While Pseudomonas aeruginosa and Salmonella typhi showed an increase in the attachment of cells to form biofilms. Morintides were very effective in the disruption of developed biofilms in cases of S. aureus, E. coli, K. pneumoniae from surgical wounds and S. flexneri, while others remained ineffective in the disruption of developed biofilms. Siderophore production was decreased by all bacterial strains under investigation in the presence of morintides except P. aeruginosa. The outcome of the research may have a significant contribution to drug discovery against antibiotic resistant biofilms of bacteria.

Peganum harmalapeptides (PhAMP) impede bacterial growth and biofilm formation in burn and surgical wound pathogens

Many clinical-pathogens have developed resistance against known antibiotics and there is an urgent need for the discovery of novel antibiotics. In this study, low molecular weight peptides were isolated from seeds/leaves of 20 medicinal plants and tested for their antibacterial activity against laboratory strains of S. aureusand P. aeruginosa. Peptides isolated from Peganum harmala (PhAMP) exhibited maximum activity against laboratory strains. As clinical-isolates are more virulent and resistant to antibiotics, we tested the potential of PhAMP on these bacterial strains isolated from infected wounds. Pathogens isolated from burn-wounds (S. aureus, P. aeruginosa and K. pneumoniae) and surgical-wounds (P. aeruginosa and K. pneumoniae) exhibited zones of inhibition against PhAMP when tested by disc diffusion method. Biofilm formation of wound pathogens in the presence/absence of PhAMP was analyzed to check its effect. Surgical-wound pathogens and K. pneumoniae from burn-wound showed significant reduction in biofilm formation and planktonic bacteria. While biofilms of S. aureus and P. aeruginosa from burn-wound showed resistance against PhAMP. An effective antibiotic treatment should not only inhibit but should also disrupt already developed biofilms. PhAMP was very effective in the disruption of developed biofilm of all pathogens after 36 hours. This data unravels the potential of PhAMP as a novel, natural antibiotic against clinical-pathogens.