A Novel Qualitative and Quantitative Biofilm Assay Based on 3D Soft Tissue

Abstract

The lack of predictable in vitro methods to analyze antimicrobial activity could play a role in the development of resistance to antibiotics. Current used methods analyze planktonic cells but for the method to be clinically relevant, biofilm in in vivo like conditions ought to be studied. Hence, our group has developed a qualitative and quantitative method with in vivo like 3D tissue for prediction of antimicrobial activity in reality. Devices (wound dressings) were applied on top of Pseudomonas aeruginosa inoculated Muller-Hinton (MH) agar or 3D synthetic soft tissues (SST) and incubated for 24 hours. The antibacterial activity was then analyzed visually and by viable counts. On MH agar two out of three silver containing devices showed zone of inhibitions (ZOI) and on SST, ZOI were detected for all three. Corroborating results were found upon evaluating the bacterial load in SST and shown to be silver concentration dependent. In conclusion, a novel method was developed combining visual rapid screening and quantitative evaluation of the antimicrobial activity in both tissue and devices. It uses tissue allowing biofilm formation thus mimicking reality closely. These conditions are essential in order to predict antimicrobial activity of medical devices in the task to prevent device related infections.

Efficacy and safety assessment of two enterococci phages in an in vitro biofilm wound model

“…In the referred study, it was shown that the biofilms formed in this model are structurally similar to biofilms observed in in vivo conditions. For this reason, CWM was already used for the study of antimicrobial activity of antibiotics and silver containing wound-dressings 39,40 .…”

Larval Therapy and Larval Excretions/Secretions: A Potential Treatment for Biofilm in Chronic Wounds? A Systematic Review

“…The necrotic tissue, slough, and wound exudate present in chronic wounds consist largely of collagen [ 57 ], providing attachment sites for pathogenic bacteria and subsequent biofilm formation [ 116 ]. Thus, collagen-based gel matrices have been used to cultivate biofilms in vitro to better mimic the chronic-wound environment [ 117 , 118 , 119 , 120 ]. With debridement as the primary antibiofilm treatment method [ 55 , 121 ], the established debridement efficacy of LT [ 97 , 122 ], the isolation of collagenases in L. sericata ES [ 123 , 124 , 125 , 126 ], and the therapeutic benefits of collagenase-based wound treatments [ 127 ], further study of the effects of ES on biofilms grown in collagen-based wound-simulating models may help to elucidate and characterize the interplay between ES constituent molecules and biofilms, providing more clinically relevant results and insights.…”

A collagen‐based layered chronic wound biofilm model for testing antimicrobial wound products

“…The main objective of this study was to create a scaffold displaying wound‐like characteristics, on which topical wound treatments could be tested. This was done in part by replacing agar with collagen as the support matrix of an existing in vitro model, as collagen has been used previously to grow wound‐relevant biofilms 18 and to mimic soft tissue infections 19–21 . Although differences between agar and collagen have yet to be evaluated extensively, some fundamental differences between the two matrix materials do exist.…”

“…The main objective of this study was to create a scaffold displaying wound-like characteristics, on which topical wound treatments could previously to grow wound-relevant biofilms 18 and to mimic soft tissue infections. [19][20][21] Although differences between agar and collagen have yet to be evaluated extensively, some fundamental differences between the two matrix materials do exist. Agar is a kelp-derived, polar carbohydrate 22 previously found to interfere with certain antibiotic compounds, 23 whereas collagen is a fibrous protein abundant in the skin of humans, and other mammals.…”