In situ Treatment With Novel Microbiocide Inhibits Methicillin Resistant Staphylococcus aureus in a Murine Wound Infection Model

Abstract

Increased prevalence of antibiotic resistance in skin and soft tissue infections is a concerning public health challenge currently facing medical science. A combinatory, broad spectrum biocidal antiseptic has been developed ("ASP") as a topically applied solution to potential resistant and polymicrobial infected wounds that may be encountered in this context. The ASP-105 designate was evaluated in vitro by determining the minimal inhibitory concentration (MIC) and minimal bactericidal concentration (MBC), against different strains of methicillin-resistant Staphylococcus aureus (MRSA), resulting estimates of which approximated the positive control (bacitracin). To evaluate in vivo microbicide efficacy, we utilized a murine full thickness wound model to study bacterial infection and wound healing kinetics. Mice were experimentally wounded dorsally and infected with bioluminescent MRSA. The infected wound was splinted, dressed and treated topically with either ASP-105, vehicle (-control), or bacitracin. Bacterial burden and wound healing was monitored using an in vivo imaging system and evaluation of biofilm formation using scanning electron microscopy of wound dressing. Treatment with ASP-105 significantly reduced bacterial burdens in the first 3 days of infection and inhibited MRSA biofilm formation on the surgical dressing. Notably, treatment with ASP-105 resulted in a sterilizing effect of any detectable MRSA in nearly all (80%; 4/5) of treatment group. All mice receiving vehicle control developed highly MRSA-luminescent and purulent wound beds as a result of experimental infection. The ASP-105 therapy facilitated natural healing in the absence of MRSA infection. Results of this study suggests that that the novel "ASP" combinatory topical antiseptic can be used directly in wounds as a potent, broadspectrum microbicide against drug resistant S. aureus without injury to the wound bed and impediment of natural restorative processes associated with wound healing. Further studies are warranted to test the effectiveness of this biocidal formulation against other recalcitrant bacterial and fungal pathogens in the context of serious wound infections, and to assess utility of use in both clinical and self-treat scenarios.

Synthetic molecular evolution of host cell-compatible, antimicrobial peptides effective against drug-resistant, biofilm-forming bacteria

“…The best peptides, D-DBS4 and D-CONGA, have excellent activity against all ESKAPE pathogens under all conditions studied. Finally, evolved peptides were tested in an animal wound model (34), with peptide added to infected wounds that are initially filled with opaque and viscous purulence (pus) due to leukocytes and secreted proteins. The results show that the selection conditions identified peptides that are active in the very challenging environment of purulent wounds infected with drug-resistant bacteria and can treat infections and prevent biofilm formation under these conditions.…”

“…All animal studies strictly adhered to protocol 131, which was approved by Tulane School of Medicine's Institutional Animal Care and Use Committee. As described (34), female CD1 mice at 8 to 12 wk of age were anesthetized via i.p. ketamine and xylazine.…”

“…The resulting host cell compatible AMPs we have evolved are highly effective in vitro against many bacterial pathogens even in the presence of concentrated host cells, and they have antibiofilm activity and gramnegative and gram-positive biofilms. In a clinically relevant wound model in mice (34), the evolved peptides are active against both gram-negative and gram-positive drug-resistant bacteria and have antibiofilm activity in infected wounds.…”

“…To begin assessing the efficacy of our lead candidate, D-CONGA, in a complex wound environment we used an established mouse model of deep surgical wound infection (34,45). Dorsal, full thickness surgical punch wounds 5 mm in diameter and 3 mm deep that penetrated the epidermis, dermis, and panniculus carnosis were made in healthy adult CD1 mice.…”

Effect of gut microbiota on depressive-like behaviors in mice is mediated by the endocannabinoid system

“…Recipient mice were given a combination of antibiotics derived from Le Roy et al 68 , namely, vancomycin (0.5 g/l), ampicillin (1 g/l), streptomycin (5 g/l), colistin (1 g/l), and metronidazole (0.5 g/l), in their drinking water for 6 consecutive days. All antibiotics were obtained from Sigma-Aldrich (St Quentin Fallavier, France).…”