BBA abstracts BBA SECTION BP1 Microdialysis to monitor burn wound metabolism in the early post-burn period: Correlation with laser doppler imaging E. E. Breuning, D. Richards, P. Gosling, N. S. Moiemen Introduction: Microdialysis is a minimally invasive method of monitoring live tissue fluid for biochemical analysis. It has great potential for monitoring the progression of the burn wound. This study aimed to correlate biochemical changes within the burn wound with Laser Doppler Image (LDI) evidence of burn wound progression. Methods: Ten adult patients with full thickness (FT) burn < 15% TBSA, were recruited. Three microdialysis probes were inserted intradermally into the centre of the burn, the periphery of the burn and unburned skin. Microdialysate was collected half hourly until 36 hours post burn and analysed for glucose, lactate, pyruvate and glycerol. Lactate: pyruvate ratio (LPR), a measure of anaerobic metabolism, was calculated. Laser Doppler Images were taken on admission and after 36 hours post-burn. Results: Three patients showed clear evidence of wound progression on LDI. Each of these patients showed biochemical evidence of local ischaemia (LPR > 25) within the burn and/or within the normal skin. A further 2 patients had borderline evidence of wound progression on LDI with signs of ischaemia on microdialysis. 1 patient had no evidence of wound progression on LDI with no evidence of ischaemia on microdialysis. Four patients had incomplete data for either microdialysis or LDI. Conclusion: For those patients with complete data, there was good correlation between microdialysis evidence of dermal ischaemia and LDI evidence of burn wound progression. This pilot study shows promising results for the use of microdialysis to monitor the progress of the burn wound through the early post-burn hours. BP2 Gram negative burn wound infection: Protagonists, trends and strategies Ernest A. Azzopardi, MRCSEd MSc Surg MD 1,2** Ernest Azzopardi is a PhD student at Cardiff University; Dean E. Boyce, FRCS (Plast) FRCS(Eng) 2 ; William A. Dickson, MBE, FRCS(Glas) FRCS 2 1 Wound Biology Group, Cardiff University, 5 th Floor, 5F03 Dental Building, Academic Ave. Heath Park, Cardiff, CF144XY 2 Welsh Centre for Burns & Plastic Surgery, Swansea, UK Abstract: Gram-negative infection remains a major contributor to morbidity mortality and cost of care but no multinational epidemiological studies specific to burn patients exist. Mapping these trends would identify pathogens of actual and imminent concern to burn physicians, develop prognostic patient profiles and facilitate the identification of novel targeting mechanisms. We sought to define a contemporary gram-negative burn wound profile and indentify trends in emerging Gram-negative burn wound infections (BWI) within the last 60 years. Methodology: Phase 1: A multiplatform and multidatabase search over 60 years; Phase 2: Evidence-based critical appraisal (140/240 studies selected). Phase 3: Retrieval of missing data from index institutions. Results: A common BWI profile was identified across 4 continents (Pseu- domonas μ = 97·6, Klebsiella μ = 30·2, Acinetobacter μ = 17·4, Enterobacter μ = 18·2, E.coli μ = 5; Proteus μ = 4 new infections/1000patient years). Fur- thermore, Aeromonas infection, although presently a minority of Gram-negative bacterial infections at present, was identified an emerging pathogen of note (76% of identified publications, Aeromonas hydrophila = 96% of isolates; mortality = 10·7%). The following patient profile indicated predisposition to Aeromonas infection: mean age (μ = 33·7 years, range 17 ≤ R ≤ 80, SD = 15·6), TBSA (μ = 41·1%, range 8% ≤ R ≤ 80%, SD = 15·2); FTSB (μ = 27·7%, range 3% ≤ R ≤ 60%, SD = 16·6) and a male predominance (81·3%). Multidrug resistance in this group was higher in burn patients than the general patient population. Stenotrophomonas maltophilia, Vibrio spp., Chryseobacterium spp. Alcaligenes xylosoxidans and Cedecia lapigei were also reported. Arresting the thermal injury by untreated water was the common predisposing factor. Discussion: Identification of a common bacterial profile allows for pre- emptive surveillance. These pathogens’ propensity to rapidly acquire multidrug resistance strongly argues for further studies to identify common molecular mechanisms across this bacterial spectrum that may be used to safely and effectively engineer antimicrobial therapy. BP3 Polymer therapeutics for effective antimicrobial targeting in burn injury E. A. Azzopardi, E. L. Ferguson, D. W. Thomas Polymer therapeutics group, Cardiff University, 5 th Floor, 5F03 Dental Building, Academic Avenue Heath Park, Cardiff, CF14 4XY Abstract: Gram-negative infection is a leading cause of mortality. Antimicrobial development has been outpaced by Gram-negative multi-drug resistance. While older antibiotics such as colistin remain effective, their use is extremely limited by their inherent nephro/neurotoxicity. Novel methods for safe and effective delivery would, therefore, radically improve patient treatment. Polymer therapeutics are nanomedicines allowing custom-engineered targeted optimal drug delivery through conjugation with a water-soluble polymer. The new macromolecule would benefit from passive targeting through the Enhanced Permeability and Retention effect. Conjugation would mask in-transit toxicity. Degradation of dextrin by α-amylase at the infected site would unmask colistin reinstating its antimicrobial activity. This study aims to develop the first fully customisable library of bioresponsive dextrin-colistin conjugates for safe and effective antimicrobial delivery in infection. A range of native dextrins (6,700–51,000 g/mol) were functionalised by succi- noylation (2–40 mol%). The resulting polymers showed correspondingly incre- mental molecular weight, but little change in polydispersity (PDI 1·52–1·82). Degradation of functionalised dextrin by α-amylase was characterised as expo- nential decay, and predictably determined by the degree of succinoylation (dextrin 2 > 5 > 10 > 15 mol%, R 2 = 0·807–0·980) and molecular weight. Subsequently, a library of dextrin-colistin conjugates was synthesized using low-molecular weight dextrin (6,700 g/mol; 2–15 mol% succinoylation). GPC and FPLC confirmed the presence of a high molecular weight conjugate, (typically 14,000–19,000 g/mol; colistin content of 9–21% w/w). Conjugates contained 0·7–1·7 dextrins per colistin molecule, attached via 2–4 binding sites. Preliminary results suggest that polymer modification predictably increases its degradation time. Dextrin-colistin conjugation is feasible and optimal conjuga- tion conditions have been identified, resulting in predictable macromolecular constructs. Significant unmasking of colistin activity in the presence of α- amylase suggests that restoration of antimicrobial activity is feasible in vivo. Further experiments will investigate antimicrobial release rates, antimicrobial activity and toxicity in-vitro and ex-vivo. BP4 Gastric perfusion: An outcome measure in burns resuscitation E. Vlachou, R. Papini, N. Moiemen University Hospital Birmingham Burns Centre, Birmingham, UK Introduction: Gastric perfusion in the acute clinical setting has been a source of great controversy. The aim of this study was to assess the predictive value of gastric perfusion monitoring during the acute phase of thermal injury. Method: Twenty adult patients with burns greater than 15% Total Body Surface Area, admitted to a single burns unit over a period of two years were recruited following informed consent. The mean TBSA was 32% (range  2011 British Journal of Surgery Society Ltd British Journal of Surgery 2011; 98(S2): 55–59 Published by John Wiley & Sons Ltd Downloaded from https://academic.oup.com/bjs/article/98/Supplement_2/55/6150451 by guest on 26 September 2022