SPaCE Swab: Point-of-Care Sensor for Simple and Rapid Detection of Acute Wound Infection

Wound infection is commonly observed after surgery and trauma but is difficult to diagnose and poorly defined in terms of objective clinical parameters. The assumption that bacteria in a wound correlate with infection is false; all wounds contain microorganisms, but not all wounds are clinically infected. This makes it difficult for clinicians to determine true wound infection, especially in wounds with pathogenic biofilms. If an infection is not properly treated, pathogenic virulence factors, such as rhamnolipids from Pseudomonas aeruginosa, can modulate the host immune response and cause tissue breakdown. Life-threatening sepsis can result if the organisms penetrate deep into host tissue. This communication describes the sensor development for five important clinical microbial pathogens commonly found in wounds: Staphylococcus aureus, P. aeruginosa, Candida albicans/auris, and Enterococcus faecalis (the SPaCE pathogens). The sensor contains liposomes encapsulating a self-quenched fluorescent dye. Toxins, expressed by SPaCE infecting pathogens in early-stage infected wounds, break down the liposomes, triggering dye release, thus changing the sensor color from yellow to green, an indication of infection. Five clinical species of bacteria and fungi, up to 20 strains each (totaling 83), were grown as early-stage biofilms in ex vivo porcine burn wounds. The biofilms were then swabbed, and the swab placed in the liposome suspension. The population density of selected pathogens in a porcine wound biofilm was quantified and correlated with colorimetric response. Over 88% of swabs switched the sensor on (10⁷–10⁸ CFU/swab). A pilot clinical study demonstrated a good correlation between sensor switch-on and early-stage wound infection.

Fluid therapy in paediatric trauma

Trauma is the most common cause of death in children over one year of age. Hypovolaemic shock is a life-threatening consequence following trauma. Hypovolaemia may be difficult to identify in children, with hypotension being a late and critical sign. Delayed capillary refill time is a useful clinical adjunct to identify hypovolaemic shock in children. This article reviews paediatric and neonatal maintenance and resuscitation fluid requirements. Fluid therapy is addressed in specific trauma circumstances including head injury, burns, and near drowning. Methods of gaining circulatory access and complications of fluid therapy are also discussed.

Prototype Development of the Intelligent Hydrogel Wound Dressing and Its Efficacy in the Detection of Model Pathogenic Wound Biofilms

The early detection of wound infection in situ can dramatically improve patient care pathways and clinical outcomes. There is increasing evidence that within an infected wound the main bacterial mode of living is a biofilm: a confluent community of adherent bacteria encased in an extracellular polymeric matrix. Here we have reported the development of a prototype wound dressing, which switches on a fluorescent color when in contact with pathogenic wound biofilms. The dressing is made of a hydrated agarose film in which the fluorescent dye containing vesicles were mixed with agarose and dispersed within the hydrogel matrix. The static and dynamic models of wound biofilms, from clinical strains of Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus, and Enterococcus faecalis, were established on nanoporous polycarbonate membrane for 24, 48, and 72 h, and the dressing response to the biofilms on the prototype dressing evaluated. The dressing indicated a clear fluorescent/color response within 4 h, only observed when in contact with biofilms produced by a pathogenic strain. The sensitivity of the dressing to biofilms was dependent on the species and strain types of the bacterial pathogens involved, but a relatively higher response was observed in strains considered good biofilm formers. There was a clear difference in the levels of dressing response, when dressings were tested on bacteria grown in biofilm or in planktonic cultures, suggesting that the level of expression of virulence factors is different depending of the growth mode. Colorimetric detection on wound biofilms of prevalent pathogens (S. aureus, P. aeruginosa, and E. faecalis) is also demonstrated using an ex vivo porcine skin model of burn wound infection.

Lack of a standardised UK care pathway resulting in national variations in management and outcomes of paediatric small area scalds

INTRODUCTION

There is a paucity of evidence guiding management of small area partial thickness paediatric scalds. This has prevented the development of national management guidelines for these injuries. This research aimed to investigate whether a lack of evidence for national guidelines has resulted in variations in both management and outcomes of paediatric small area scalds across England and Wales (E&W).

METHODS

A national survey of initial management of paediatric scalds ≤5% Total Body Surface Area (%TBSA) was sent to 14 burns services in E&W. Skin graft rates of anonymised burns services over seven years were collected from the international Burns Injury Database (iBID). Average skin grafting rates across services were compared. Length of stay and proportion of patients receiving general anaesthesia for dressing application at each service were also compared.

RESULTS

All 14 burns services responded to the survey. Only 50% of services had a protocol in place for the management of small area burns. All protocols varied in how partial thickness paediatrics scalds ≤5% TBSA should be managed. There was no consensus as to which scalds should be treated using biosynthetic dressings. Data from iBID for 11,917 patients showed that the average reported skin grafting rate across all burns services was 2.3% (95% CI 2.1, 2.6) but varied from 0.3% to 7.1% (P<0.001). Service provider remained associated with likelihood of skin grafting when variations in the %TBSA case mix seen by each service were controlled for (χ(2)=87.3, P<0.001). The use of general anaesthetics across services varied between 0.6 and 35.5% (P<0.001). The median length of stay across services varied from 1 to 3 days (P<0.001).

DISCUSSION

A lack of evidence guiding management of small-area paediatric scalds has resulted in variation in management of these injuries across E&W. There is also significant variation in outcomes for these injuries. Further research is indicated to determine if care pathways and outcomes are linked. An evidence-based national policy for the management of small area paediatric scalds would ensure that high quality, standardised care is delivered throughout E&W and variations in outcome are reduced.

Impact of reduced resuscitation fluid on outcomes of children with 10-20% body surface area scalds

'Permissive hypovolaemia' fluid regimes in adult burn care are suggested to improve outcomes. Effects in paediatric burn care are less well understood. In a retrospective audit, outcomes of children from the South West Children's Burn Centre (SWCBC) less than 16 years of age with scalds of 10-20% burn surface area (BSA) managed with a reduced volume fluid resuscitation regime (post-2007) were compared to (a) an historical local protocol (pre-2007) and (b) current regimes in burn services across England and Wales (E&W). Outcomes included length of stay per percent burn surface area (LOS/%BSA), skin graft requirement and re-admission rates. 92 SWCBC patients and 475 patients treated in 15 other E&W burn services were included. Median LOS/%BSA for patients managed with the reduced fluid regime was 0.27 days: significantly less than pre-2007 and other E&W burn services (0.54 days, 0.50 days, p<0.001). Skin grafting to achieve healing reduced post-2007 compared to pre-2007 and remains comparable with other E&W services. Re-admission rates were comparable between all groups. A reduced fluid regime has significantly shortened LOS/%BSA without compromising burn depth as measured by skin grafting to achieve healing. A prospective trial comparing permissive hypovolaemia to current regimes for moderate paediatric scald injuries would help clarify.

Preventing venous thrombosis in critically ill children: what is the right approach?

BACKGROUND

The incidence of venous thromboembolic (VTE) events in children has increased in recent years (J Neurosurg, 101, 2004, 32; J Thromb Haemost, 1, 2003, 1443) yet there is currently no consensus as to what VTE prophylaxis, if any, should be applied to the pediatric population.

OBJECTIVES/AIMS

Our aim was to audit current practice in pediatric VTE prophylaxis across England and Wales and to advocate simple measures for prevention. We illustrate the importance of the condition with a series of cases from the South West Paediatric Burns and Neurosurgical Services based in Bristol.

METHODS

Every pediatric intensive care unit (PICU) and burns center admitting children in England and Wales was invited to participate in a structured telephone questionnaire designed to find out how VTE in children were being prevented. We performed a literature review of specific risk factors and management of these factors.

RESULTS

Only one of the 24 units surveyed had written guidelines specific for children. Four other units used modified adult guidelines in older children. In the remaining 19 units that had no written guidelines, decisions regarding prophylaxis were based on individual cases and consultant-led.

CONCLUSION

There is no consensus in England and Wales as to which VTE prophylactic measures should be applied in patients <18 years of age. The National Institute for Health and Clinical Excellence (NICE) guidelines apply to adults only. Given the rarity of VTE events in children, it is unlikely that randomized controlled trials will provide the answer. We therefore propose that simple empirical measures be formally implemented in critically ill children to reduce the risk of developing this important but under-recognized condition.

Severe staphylococcal scalded skin syndrome in children

Staphylococcal scalded skin syndrome (SSSS) is a rare toxin-mediated condition caused by Staphylococcus aureus, which causes blistering and desquamation of the skin. Between November 2005 and April 2006, four children were admitted to critical care beds in the South West Regional Paediatric Burns Unit because of SSSS affecting more than 50% of the body surface area. Details of these cases are presented, highlighting the potential severity of the condition. The cases also illustrate that fluid overload is a common complication of the condition, despite hypovolaemia being the more obvious risk, and that both hyponatraemia and leukopenia are frequent findings. These summaries clearly demonstrate the need for paediatric critical care in a tertiary burns unit for children with SSSS affecting a large proportion of the body surface area. The cluster of admissions prompted us to write a management protocol for children with severe SSSS and a summary of this is provided. Most children with SSSS will initially present to general paediatric units, where mild cases will be managed, but severe cases should be promptly referred to a tertiary paediatric burns unit for multi-disciplinary care in a critical care environment.

The cost of a hot drink scald

Approximately 6400 children per year are admitted to UK hospitals for treatment of burns [National Burn Care Review Committee Report (NBCRC). Standards and Strategy for Burn Care: a review of burn care in the British Isles. 2001.]. This paper investigates the financial costs involved in the management of uncomplicated, minor paediatric scalds. Three cases (2-4% TBSA scalds) were studied to quantify consumables used, services required during management and costs obtained from appropriate Purchasing Departments and Directorate Accountants. Management in all cases involved a general anaesthetic for cleaning of wounds, application of BioBrane (Bertek Pharmaceuticals) and dressings, observation on Children's Ward and discharge following wound review at 48 h. The calculated mean average cost per case was pound1850. In the period 01/12/2002-30/11/2003, 144 children were admitted to Frenchay hospital, Bristol, for treatment of a minor burn or scald (less than 10%TBSA). This caseload is therefore estimated to currently cost pound266,400 per year. These findings may facilitate improved planning for future resource allocation and could also contribute evidence towards the cost effectiveness of prevention strategies.

Early diagnosis and treatment of toxic shock syndrome in paediatric burns

Young children with burns are at risk of developing toxic shock syndrome (TSS), which is an exotoxin mediated disease usually caused by Staphylococcus aureus (S. aureus). The diagnosis of TSS is difficult because in the early stages the signs and symptoms resemble other common childhood illnesses such as scarlet fever. If the condition is not treated promptly it has a high mortality. The South West Regional Paediatric Burns Unit at Frenchay Hospital admits 150-200 burns per year. We have designed a protocol to facilitate the early diagnosis and treatment of TSS. We report our experience over a 3-year period in which almost one quarter of cases of TSS were admitted from home or another hospital. During this period all children with TSS survived and none needed ventilatory support. Typical cases presented within 2 days of thermal injury, in a child under 2 years old with a burn of less than 10% of body surface area (BSA).