Robertson Shaun N, Romero Manuel, Fenn Samuel, Kohler Riedi Petra L, Cámara Miguel
National Biofilms Innovation Centre, School of Life Sciences, Biodiscovery Institute, University of Nottingham, NG7 2RD Nottingham, United Kingdom.
Department of Microbiology and Parasitology, Faculty of Biology-CIBUS, Universidade de Santiago de Compostela, Santiago de Compostela 15782, Spain.
J Appl Microbiol. 2024 Mar 1;135(3). doi: 10.1093/jambio/lxae042.
Chronic wound infections are generally of polymicrobial nature with aerobic and anaerobic bacteria, as well as fungi frequently observed in them. Wound treatment involves a series of steps, including debridement of the wound, flushing, and often the use of multiple wound dressings many of which are antimicrobial. Yet, many wound dressings are tested versus single species of planktonic microbes, which fails to mirror the real-life presence of biofilms.
Simple biofilm models are the first step to testing of any antimicrobial and wound dressing; therefore, the aim of this study was to develop and validate a simple polymicrobial colony biofilm wound model comprised of Pseudomonas aeruginosa, Staphylococcus aureus, and Candida albicans on RPMI-1640 agar. The model was then used to evaluate the topical disinfectant chlorohexidine and four commercially available wound dressings using the polymicrobial model. The model used was as a starting point to mimic debridement in clinical care of wounds and the effectiveness of wound dressings evaluated afterwards.
Planktonic assessment using AATCC100-2004 demonstrated that all antimicrobial wound dressings reduced the planktonic microbial burden below the limit of detection; however, when challenged with polymicrobial colony biofilms, silver wound dressings showed limited effectiveness (1-2 log CFU reductions). In contrast, a single iodine releasing wound dressing showed potent antibiofilm activity reducing all species CFUs below the limit of detection (>6-10 log) depending on the species. A disrupted biofilm model challenge was performed to represent the debridement of a wound and wound silver-based wound dressings were found to be marginally more effective than in whole colony biofilm challenges while the iodine containing wound dressing reduced microbial recovery below the limit of detection.
In this model, silver dressings were ineffective versus the whole colony biofilms but showed some recovery of activity versus the disrupted colony biofilm. The iodine wound dressing reduced the viability of all species below the level of detection. This suggests that mode of action of wound dressing should be considered for the type of biofilm challenge as should the clinical use, e.g. debridement.
慢性伤口感染通常具有多种微生物特性，其中需氧菌、厌氧菌以及真菌都很常见。伤口治疗包括一系列步骤，如伤口清创、冲洗，并且常常使用多种伤口敷料，其中许多具有抗菌作用。然而，许多伤口敷料仅针对单一浮游微生物物种进行测试，这无法反映生物膜在现实中的存在情况。
简单的生物膜模型是测试任何抗菌剂和伤口敷料的第一步；因此，本研究的目的是开发并验证一种简单的多微生物菌落生物膜伤口模型，该模型由铜绿假单胞菌、金黄色葡萄球菌和白色念珠菌在RPMI - 1640琼脂上组成。然后使用该模型评估局部消毒剂洗必泰和四种市售伤口敷料。所使用的模型作为模拟伤口临床护理中清创的起点，随后评估伤口敷料的有效性。
使用AATCC100 - 2004进行的浮游菌评估表明，所有抗菌伤口敷料都将浮游微生物负荷降低到检测限以下；然而，当受到多微生物菌落生物膜挑战时，银质伤口敷料显示出有限的效果（减少1 - 2个对数CFU）。相比之下，一种单一的释放碘的伤口敷料显示出强大的抗生物膜活性，根据物种不同，可将所有物种的CFU降低到检测限以下（>6 - 10个对数）。进行了破坏生物膜模型挑战以代表伤口清创，发现基于银的伤口敷料在破坏生物膜模型挑战中比在全菌落生物膜挑战中略有效，而含碘伤口敷料将微生物回收率降低到检测限以下。
在该模型中，银质敷料对全菌落生物膜无效，但对破坏的菌落生物膜显示出一定的活性恢复。含碘伤口敷料将所有物种的活力降低到检测水平以下。这表明应根据生物膜挑战的类型以及临床用途（如清创）来考虑伤口敷料的作用方式。
