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Open AccessArticle

The Effect of Negative Pressure Wound Therapy with and without Instillation on Mature Biofilms In Vitro

Surgical Infection Research Group, Faculty of Medicine and Health Sciences, Macquarie University, Sydney 2109, Australia
Infectious Diseases and Microbiology, School of Medicine, Western Sydney University, Sydney 2751, Australia
Liverpool Diabetes Collaborative Research Unit, Ingham Institute of Applied Medical Research, Sydney 2170, Australia
High Risk Foot Service, Liverpool Hospital, South West Sydney LHD, Sydney 2170, Australia
Author to whom correspondence should be addressed.
Materials 2018, 11(5), 811;
Received: 15 March 2018 / Revised: 8 May 2018 / Accepted: 14 May 2018 / Published: 16 May 2018
(This article belongs to the Special Issue Microbial Biofilms in Healthcare: Formation, Prevention and Treatment)
Background: To investigate the effect of negative pressure wound therapy (NPWT) with and without instillation (NPWTi) on in vitro mature biofilm. Methods: Mature biofilms of Pseudomonas aeruginosa and Staphylococcus aureus were grown under shear (130 rpm) on polycarbonate coupons in a CDC biofilm reactor for 3 days. Coupons containing biofilms were placed in a sterile petri dish and sealed using NPWT or NPWTi. Coupons were exposed to treatment for 24 h with NPWT alone or with instillation of: Povidone iodine solution (PVP-I) (10% w/v equivalent to 1% w/v available iodine, BETADINE®, Mundipharma, Singapore), surfactant based antimicrobial solution with polyhexamethylene biguanide (SBPHMB) (Prontosan®, B Braun Medical, Melsungen, Germany), Gentamicin 1 µg/mL (GM) (G1264 Sigma-Aldrich Pty Ltd., Castle Hill, Australia) Rifampicin 24 µg/mL (RF) (R3501 Sigma-Aldrich Pty Ltd., Castle Hill, Australia) and NaCl 0.9% (Baxter, Deerfield, IL, USA). Bacterial cell viability and biofilm architecture pre-and post-treatment were assessed using colony forming units (cfu), Live/Dead viability staining, confocal laser scanning microscopy (CLSM) and scanning electron microscopy (SEM). Results: Significant reductions were obtained in S. aureus biofilm thickness (65%) and mass (47%) when treated with NPWTi as compared to NPWT only. NPWTi with instillation of SBPHMB, PVP-I and RF achieved between 2 and 8 log10 reductions against S. aureus biofilm (p < 0.05–0.001). Conversely, PVP-I and SBMO achieved a 3.5 log10 reduction against P. aeruginosa (p < 0.05). Conclusions: NPWT alters biofilm architecture by reducing biofilm thickness and mass, but this does not affect bacterial cell viability. NPWT with instillation of certain antimicrobials solutions may provide a further synergistic effect in reducing the number of viable biofilm microorganisms. Our in vitro model may be used for screening the effectiveness of antimicrobials used under instillation prior to animal or human studies. View Full-Text
Keywords: biofilm; chronic wounds; instillation therapy; in vitro biofilm; chronic wounds; instillation therapy; in vitro
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MDPI and ACS Style

Tahir, S.; Malone, M.; Hu, H.; Deva, A.; Vickery, K. The Effect of Negative Pressure Wound Therapy with and without Instillation on Mature Biofilms In Vitro. Materials 2018, 11, 811.

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