Negative-Pressure Wound Therapy in aPseudomonas aeruginosaInfection Model

Abstract

Background Negative-pressure wound therapy (NPWT) is an effective strategy for the management of contaminated wounds, including those infected by Pseudomonas aeruginosa. We hypothesized that NPWT would reduce virulence factors as well as biofilm components and inhibit virulence-regulated gene expression in a model of P. aeruginosa wound infection. Methods Wounds were created in anesthetized rabbits and P. aeruginosa was inoculated to the wound surface for 24 h. Wounds were treated with either NPWT or a sterile gauze dressing. Virulence factors including exotoxin A, rhamnolipid, and elastase were quantified by the enzyme-linked immunosorbent assay, orcinol, and elastin-Congo red methods, respectively. A biofilm component, eDNA, was quantified using a commercial kit. Virulence-regulated genes were determined by quantitative real-time polymerase chain reaction (RT-PCR). Biofilms were observed in vivo by staining with concanavalin A conjugated to Alexa Fluor® 647. Results NPWT was more effective than the control treatment in reducing virulence factors and bacteria counts in vivo. A biofilm component, eDNA, was less abundant in the NPWT group. The results of the RT-PCR indicated that the expression levels of P. aeruginosa virulence-regulated genes and quorum-sensing population density-dependent systems were significantly inhibited by NPWT treatment. Conclusion NPWT reduced bacteria counts, virulence factors, and eDNA in a P. aeruginosa wound infection model in vivo. These beneficial effects are likely to be related to the reduced expression of virulence-regulated genes and the drainage induced by NPWT treatment. These findings may help clinicians to obtain a better understanding of the mechanism of NPWT for the treatment of infected wounds.

Pre-Clinical Assessment of Single-Use Negative Pressure Wound Therapy During In Vivo Porcine Wound Healing

“…NPWT devices generate negative pressure between −50 and −175 mmHg, 7 removing excess wound exudate through a drainage tube and preventing bacterial contamination. 8 , 9 Early studies demonstrated that traditional NPWT (tNPWT) promotes granulation tissue formation in pigs 10 and in the clinical setting. 11 , 12 Additional healing promoting effects of NPWT also include pulling wound margins together to accelerate contraction, stimulating cellular proliferation by microdeformation, 13 , 14 and increasing tissue perfusion.…”

Benefits of Acidifying Agents in Local Therapy of Diabetic Foot Ulcers Infected by Pseudomonas sp: A Pilot Study

“…According to some studies, NPWT can potentially counteract Pseudomonas sp. 26 Maggot therapy is not effective in Pseudomonas -infected wounds probably due to the side effects of exotoxins produced by strains of Pseudomonas aeruginosa that inhibit ciliary activity in larvae and disturb processes of cell differentiation in embryos and larvae. Their toxic influence is accompanied by disturbances of protein synthesis and disruptions to the cytoskeleton during zygote cleavage and larval development.…”

Recent Advances in Non-Conventional Antimicrobial Approaches for Chronic Wound Biofilms: Have We Found the ‘Chink in the Armor’?

“…NPWT targets several key factors in the chronic wound infection microenvironment such as decreasing the accumulation of exudate, enhancing granulation tissue and blood vessel formation, improving oxygen and nutrient supply, which possibly contribute to its antimicrobial effects. The effectiveness of NPWT as an antimicrobial approach has been studied, particularly in conjunction with wound instillation [125,126]. In recent work, the effects of NPWT in conjunction with automated wound antiseptic irrigation was investigated on 111 patients with infected wounds [127].…”