A proof-of-concept study of the removal of early and late phase biofilm from skin wound models using a liquid acoustic stream.

Chronic wounds fail to progress through the normal stages of healing, with the largest remediable cause of chronicity being presence of a multi-species biofilm. Removal of biofilm from the wound environment is central to wound care. A device for mechanically removing biofilms from wounds has been devised. The removal is caused by small-scale liquid currents and shear, generated by acoustically activated microscopic air bubbles. These bubbles and acoustic waves are delivered onto the wound by a gentle liquid stream, allowing cleaning in situ and removal of debris in the run-off liquid. We have investigated if this liquid acoustic wound stream (LAWS) can remove bacterial biofilm from soft biological wound models and studied the effect of LAWS on the cellular tissues of the substrate. LAWS will efficiently remove early Pseudomonas aeruginosa biofilm from an artificial wound in a pig's trotter, 24 hours-mature biofilm of P. aeruginosa from a pre-wounded human full thickness skin model (EpiDerm FT), and 3-day mature biofilm of P. aeruginosa or Staphylococcus aureus from a porcine skin explant. Histological examinations of uninfected EpiDerm models that had been treated by LAWS and then stained with Haematoxylin and Eosin, demonstrated no damage to the human tissue, and wound diameter was smaller in the treated skin models compared with untreated samples. Immunofluorescence staining for cytokeratin 14 showed that keratinocytes had migrated further across the wound in the uninfected samples treated by LAWS. We discuss the implications for wound healing and propose further laboratory and clinical studies to demonstrate the removal of biofilm from patients with chronic leg ulcers and the impact on healing.

Pseudomonas aeruginosa transcriptome adaptations from colonization to biofilm infection of skin wounds.

In burn patients Pseudomonas aeruginosa infection is a major cause of morbidity. Analysis of the pathogen's gene expression as it transitions from colonization to acute and then biofilm wound infection may provide strategies for infection control. Toward this goal, we seeded log-phase P. aeruginosa (PAO1) into 3-day-old, full-thickness excision wounds (rabbit ear) and harvested the bacteria during colonization (Hrs 2 and 6), acute infection (Hr 24), and biofilm infection (Days 5 and 9) for transcriptome analysis (RNA-Seq). After 2-6 h in the wound, genes for metabolism and cell replication were down-regulated while wound-adaptation genes were up-regulated (vs. expression in log-phase culture). As the infection progressed from acute to biofilm infection, more genes became up-regulated than down-regulated, but the down-regulated genes enriched in more pathways, likely because the genes and pathways that bacteria already colonizing wounds up-regulate to establish biofilm infection are less known. Across the stages of infection, carbon-utilization pathways shifted. During acute infection, itaconate produced by myeloid cells appears to have been a carbon source because myeloid cell infiltration and the expression of the host gene, ACOD1, for itaconate production peaked coincidently with the expression of the PAO1 genes for itaconate transport and catabolism. Additionally, branched-chain amino acids are suggested to be a carbon source in acute infection and in biofilm infection. In biofilm infection, fatty acid degradation was also up-regulated. These carbon sources feed into the glyoxylate cycle that was coincidently up-regulated, suggesting it provided the precursors for P. aeruginosa to synthesize macromolecules in establishing wound infection.

Imaging and Targeted Antibacterial Therapy Using Chimeric Antimicrobial Peptide Micelles.

Infectious diseases induced by multidrug-resistant bacteria are a challenging problem in medicine because of global rise in the drug resistance to pathogenic bacteria. Despite great efforts on the development of antibiotics and antimicrobial agents, there is still a great need to develop a strategy to early detect bacterial infections and eradicate bacteria effectively and simultaneously. The innate immune systems of various organisms produce antimicrobial peptides, which kill a broad range of bacteria with minimal cytotoxicity to mammalian cells. Therefore, antimicrobial peptides have recently attracted increasing attention as an alternative to conventional antibiotics in antibacterial medications. Here, we report a new family of antibacterial agents, which is formulated from self-assembly of a chimeric antimicrobial lipopeptide (DSPE-HnMc) and amphiphilic biodegradable polymers. HnMc micelles could effectively bind the bacterial membrane to kill a wide spectrum of bacteria and bacterial biofilms. In the studies of mouse models of drug-resistant bacterial infections, HnMc micelles could target bacterial infections with high specificity and also kill drug-resistant bacteria effectively, demonstrating the great potential of HnMc micelles as imaging and targeted antibacterial agents. These findings also provide new insight into the design of antimicrobial peptide-based nanomedicine for detection and treatment of bacterial infections.

Successful bedaquiline-containing antimycobacterial treatment in post-traumatic skin and soft-tissue infection by Mycobacterium fortuitum complex: a case report.

BACKGROUND: Mycobacterium fortuitum complex is a group of rapidly growing nontuberculous mycobacteria (NTM) associated with skin and soft-tissue infections after surgery or trauma. Treatment of NTM is challenging, due to resistance to multiple antimycobacterial agents. Bedaquiline is a diarylquinoline that inhibits mycobacterial ATP-synthase. The drug has recently been approved for the treatment of multidrug-resistant tuberculosis and evidence of its in vitro efficacy against NTM, including Mycobacterium fortuitum complex, has been published. CASE PRESENTATION: A 20-year-old Caucasian woman with chronic skin and soft tissue infection in the lower leg following a traffic accident in Vietnam underwent a tedious journey of healthcare visits, hospital admissions, empiric antimicrobial treatments, surgical debridement and plastic reconstruction before definite diagnosis of Mycobacterium fortuitum complex-infection was established by culture from a tissue biopsy and targeted antimycobacterial therapy was administered. Histopathological examination revealed granulomatous purulent inflammation, which strongly supported the diagnosis. Genotypic identification was performed and broth microdilution for susceptibility testing showed macrolide resistance. Five weeks of induction treatment with intravenous amikacin, imipenem / cilastin, and oral levofloxacin was administered, followed by all-oral treatment with bedaquiline combined with levofloxacin for four months, which was well-tolerated and led to persistent healing with scars but without signs of residual infection. CONCLUSIONS: Bedaquiline is a promising novel agent for NTM treatment, although clinical data are limited and trials evaluating efficacy, safety, and resistance of bedaquiline are required. To our knowledge, this is the first reported case of successful in vivo use of bedaquiline for a skin and soft tissue infection caused by Mycobacterium fortuitum complex.

Formation of Pseudomonas aeruginosa Biofilms in Full-thickness Scald Burn Wounds in Rats.

Using Sprague-Dawley rats (350-450 g; n = 61) and the recently updated Walker-Mason rat scald burn model, we demonstrated that Pseudomonas aeruginosa readily formed biofilms within full-thickness burn wounds. Following the burn, wounds were surface-inoculated with P. aeruginosa in phosphate-buffered saline (PBS), while sterile PBS was used for controls. On post-burn days 1, 3, 7, and 11, animals were euthanized and samples collected for quantitative bacteriology, bacterial gene expression, complete blood cell counts, histology, and myeloperoxidase activity. Robust biofilm infections developed in the full-thickness burn wounds inoculated with 1 × 104 CFU of P. aeruginosa. Both histology and scanning electron microscopy showed the pathogen throughout the histologic cross-sections of burned skin. Quantigene analysis revealed significant upregulation of alginate and pellicle biofilm matrix genes of P. aeruginosa within the burn eschar. Additionally, expression of P. aeruginosa proteases and siderophores increased significantly in the burn wound environment. Interestingly, the host's neutrophil response to the pathogen was not elevated in either the eschar or circulating blood when compared to the control burn. This new full-thickness burn biofilm infection model will be used to test new anti-biofilm therapies that may be deployed with soldiers in combat for immediate use at the site of burn injury on the battlefield.

Open tibial fractures in major trauma centres: A national prospective cohort study of current practice.

AIMS: To assess current national practice in the management of severe open tibial fractures against national standards, using data collected by the Trauma and Audit Research Network. MATERIALS AND METHODS: Demographic, injury-specific, and outcome data were obtained for all grade IIIB/C fractures admitted to Major Trauma Centres in England from October 2014 to January 2016. RESULTS: Data was available for 646 patients with recorded grade IIIB/C fractures. The male to female ratio was 2.3:1, mean age 47 years. 77% received antibiotics within 3 h of admission, 82% were debrided within 24 h. Soft tissue coverage was achieved within 72 h of admission in 71%. The amputation rate was 8.7%. 4.3% of patients required further theatre visits for infection during the index admission. The timing of antibiotics and surgery could not be correlated with returns to theatre for early infection. There were significant differences in the management and outcomes of patients aged 65 and over, with an increase in mortality and amputation rates. CONCLUSIONS: Good outcomes are reported from the management of IIIB/C fractures in Major Trauma Centres in England. Overall compliance with national standards is particularly poor in the elderly. Compliance did not appear to affect rates of returning to theatre or early infection. Appropriately applied patient reported outcome measures are needed to enhance the evidence-base for management of these injuries.

[Antiseptic effect of compound lysostaphin disinfectant and its preventive effect on infection of artificial dermis after graft on full-thickness skin defect wound in rats].

Objective: To study the antiseptic effect of compound lysostaphin disinfectant and its preventive effect on infection of artificial dermis after graft on full-thickness skin defect wound in rats. Methods: (1) Each one standard strain of Klebsiella pneumoniae, Acinetobacter baumannii, and Staphylococcus aureus were selected. Each 20 clinical strains of Klebsiella pneumoniae, Acinetobacter baumannii, and Staphylococcus aureus were collected from those isolated from wound exudates of burn patients hospitalized in our wards from January 2014 to December 2016 according to the random number table. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of compound lysostaphin disinfectant to above-mentioned strains were detected. The experiment was repeated 3 times. Compared with the corresponding standard strain, the clinical strain with higher MIC and/or MBC was considered as having decreased sensitivity to the disinfectant. The percentage of strains of each of the three kinds of bacteria with decreased sensitivity was calculated. (2) Artificial dermis pieces were soaked in compound lysostaphin disinfectant for 5 min, 1 h, 2 h, and 4 h, respectively, with 21 pieces at each time point. After standing for 0 (immediately), 12, 24, 36, 48, 60, 72 h (with 3 pieces at each time point), respectively, the diameters of their inhibition zones to standard strains of Klebsiella pneumoniae, Acinetobacter baumannii, and Staphylococcus aureus were measured. The experiment was repeated 3 times. The shortest soaking time corresponding to the longest standing time, after which the disinfectant-soaked artificial dermis could form an effective inhibition zone (with diameter more than 7 mm), was the sufficient soaking time of the disinfectant to the artificial dermis. (3) Forty Sprague-Dawley rats were divided into post injury day (PID) 3, 7, 14, and 21 sampling groups according to the random number table, with 10 rats in each group. A full-thickness skin defect wound with a diameter of 20 mm was made on both sides of the spine on the back of each rat. Immediately after injury, the artificial dermis without any treatment was grafted on the wound on left side of the spine (hereinafter referred to as control wound), while the sufficiently soaked artificial dermis with compound lysostaphin disinfectant was grafted on the wound on right side of the spine (hereinafter referred to as disinfectant wound). On PID 3, 7, 14, and 21, the gross condition of wounds of all the surviving rats was observed, and the new infection rates of control wounds and disinfectant wounds were calculated. Then, the rats in the sampling group with corresponding time were killed, and the full-thickness wound tissue containing artificial dermis was collected for quantitative analysis of bacteria. Bacteria content of the uninfected control wounds and that of the uninfected disinfectant wounds were compared. Data were processed with chi-square test and Wilcoxon rank sum test. Results: (1) The MIC of compound lysostaphin disinfectant to standard strains of Staphylococcus aureus, Klebsiella pneumoniae, and Acinetobacter baumannii were 1/32, 1/32, and 1/512 of the original concentration of the disinfectant, respectively, and the MBC were 1/32, 1/16, and 1/512 of the original concentration of the disinfectant, respectively. The percentages of clinical strains of Klebsiella pneumoniae, Acinetobacter baumannii and Staphylococcus aureus with decreased sensitivity to compound lysostaphin disinfectant were 15% (3/20), 20% (4/20), and 10% (2/20), respectively. (2) After being soaked in compound lysostaphin disinfectant for 2 and 4 h, the longest standing time, after which the artificial dermis could form an effective inhibition zone against Klebsiella pneumoniae, Acinetobacter baumannii, and Staphylococcus aureus, were 24, 36, and 48 h respectively, longer than 12, 24, and 24 h of soaking for 5 min and 24, 24, and 36 h of soaking for 1 h. The sufficient soaking time of compound lysostaphin disinfectant to artificial dermis was 2 h. (3) On PID 3, no infection symptom was observed in all the wounds, and so both the new infection rate of control wounds and that of disinfectant wounds were 0. The artificial dermis was transparent but not well connected with the wound. On PID 7, the new infection rate of control wounds was 20.00% (6/30), which was obviously higher than 3.33% (1/30) of disinfectant wounds, χ(2)=4.043, P<0.05. On the infected wound, a large amount of purulent exudates were observed, and the artificial dermis was not connected with the wound and degraded partially. On the uninfected wound, artificial dermis was transparent and had a partial connection with the wound. On PID 14 and 21, no new infected wound was observed, and so both the new infection rate of control wounds and that of disinfectant wounds were 0. There was no obvious improvement on the infected wounds. The collagen layers of artificial dermis in the uninfected wound established a good connection with the wound and were separating from the silica gel layer gradually. Infection occurred in 2, 3, 1 control wound (s) in PID 7, 14, and 21 sampling groups, respectively, and in 1 disinfectant wound in PID 14 sampling group. The bacteria content of the infected wounds tissue was 0.79×10(6) to 7.22×10(9) colony-forming unit (CFU)/g. The bacteria content of uninfected control wounds tissue in PID 3, 7, and 14 sampling groups were (3.43±1.88)×10(2,) (2.37±0.43)×10(3,) and (8.40±1.03)×10(3) CFU/g, respectively, which were significantly higher than (0.33±0.12)×10(2,) (0.43±0.17)×10(3,) (2.16±0.52)×10(3) CFU/g of uninfected disinfectant wounds tissue (Z=-3.780, -3.554, -3.334, P<0.05). The bacteria content of uninfected control wounds tissue and that of uninfected disinfectant wounds tissue in PID 21 sampling group were similar (Z=-0.490, P>0.05). Conclusions: Compound lysostaphin disinfectant has quite strong antibacterial ability against Klebsiella pneumoniae, Acinetobacter baumannii, and Staphylococcus aureus. Clinical strains of the three kinds of bacteria were highly sensitive to compound lysostaphin disinfectant. Saturation of absorption of compound lysostaphin disinfectant achieves in artificial dermis after 2 hours' soaking. After 24, 36, and 48 hours' standing, the soaked artificial dermis still has the antibacterial effect on Klebsiella pneumoniae, Acinetobacter baumannii, and Staphylococcus aureus, respectively. The infection rate and the bacteria content of full-thickness skin defect wound in rats are all decreased when grafted with soaked artificial dermis.

Propionibacterium acnes and Staphylococcus epidermidis olecranon bursitis/osteomyelitis: a case involving surgical and antibiotic treatment.

This report describes a 63-year-old generally healthy male with septic olecranon bursitis caused by Propionibacterium acnes The patient sustained a small laceration after striking the posterior aspect of his left elbow on a metal railing when he was at a public swimming pool. We concluded that P. acnes was not initially detected because cultures were only kept for 5 days. Consequently, initial antibiotic treatment failed. P. acnes and Staphylococcus epidermidis grew in a subsequent tissue culture. The infection did not respond to intravenous vancomycin although soft-tissue debridements were done. This likely reflected the presence of olecranon osteomyelitis (seen on MRI scans) in addition to inadequate treatment with this antibiotic in the setting of a polymicrobial infection. Eventually, the infection was eradicated with multiple soft-tissue debridements in addition to the continuation of vancomycin with daily intravenous piperacillin/tazobactam that was added for the final 4 weeks of antibiotic treatment.

Unusual Morel-Lavallee lesion of the knee region in an elderly patient.

The Morel-Lavallee lesion (MLL) of the knee region has been described in the Orthopaedic literature, and all of those were fit and healthy young participants sustaining sports-related trauma to the knee. We describe a case of an elderly woman, on aspirin and prophylactic clexane, who sustained a low-energy injury to the right knee and developed an MLL of the knee region. A delayed recognition, led to the persistence of the MLL as a diffuse haematoma, which subsequently became colonised with methicillin-resistant Staphylococcus aureus We discuss the management of a case and highlight the importance of early identification and management of MLL of the knee region. Further evidence needs to be collected about MLL lesions in elderly, frail patients who are anticoagulated, and have increased risk of falls. This cohort of patients is more vulnerable to bleeding and infection than a fit, young adult population.

Staged minimally invasive plate osteosynthesis of proximal tibial fractures with acute compartment syndrome.

PURPOSE: High-energy proximal tibial fractures often accompany compartment syndrome and are usually treated by fasciotomy with external fixation followed by secondary plating. However, the initial soft tissue injury may affect bony union, the fasciotomy incision or external fixator pin sites may lead to postoperative wound infections, and the staged procedure itself may adversely affect lower limb function. We assess the results of staged minimally invasive plate osteosynthesis (MIPO) for proximal tibial fractures with acute compartment syndrome. METHODS: Twenty-eight patients with proximal tibial fractures accompanied by acute compartment syndrome who underwent staged MIPO and had a minimum of 12 months follow-up were enrolled. According to the AO/OTA classification, 6 were 41-A, 15 were 41-C, 2 were 42-A and 5 were 42-C fractures; this included 6 cases of open fractures. Immediate fasciotomy was performed once compartment syndrome was diagnosed and stabilization of the fracture followed using external fixation. After the soft tissue condition normalized, internal conversion with MIPO was done on an average of 37 days (range, 9-158) after index trauma. At the time of internal conversion, the external fixator pin site grades were 0 in 3 cases, 1 in 12 cases, 2 in 10 cases and 3 in 3 cases, as described by Dahl. Radiographic assessment of bony union and alignment and a functional assessment using the Knee Society Score and American Orthopedic Foot and Ankle Society (AOFAS) score were carried out. RESULTS: Twenty-six cases achieved primary bony union at an average of 18.5 weeks. Two cases of nonunion healed after autogenous bone grafting. The mean Knee Society Score and the AOFAS score were 95 and 95.3 respectively, at last follow-up. Complications included 1 case of osteomyelitis in a patient with a grade IIIC open fracture and 1 case of malunion caused by delayed MIPO due to poor wound conditions. Duration of external fixation and the external fixator pin site grade were not related to the occurrence of infection. CONCLUSIONS: Staged MIPO for proximal tibial fractures with acute compartment syndrome may achieve satisfactory bony union and functional results, while decreasing deep infections and soft tissue complications.

Novel foam dressing using negative pressure wound therapy with instillation to remove thick exudate.

We describe our experience with a novel foam dressing architecture in tandem with negative pressure wound therapy and instillation (NPWTi-d) for removing viscous wound exudate and infectious materials. A retrospective review was conducted of the outcomes of 21 patients who received NPWTi-d using a reticulated open cell foam instillation dressing with through holes (ROCF-CC) designed to facilitate the removal of thick wound exudate and infectious materials. NPWTi-d with ROCF-CC was used to treat large complex chronic wounds with viscous wound exudate that contained substantial areas of devitalised tissue. Debridement was performed as appropriate or available. NPWTi-d with ROCF-CC assisted in loosening, solubilising and detaching viscous exudate, dry fibrin, wet slough and other infectious materials. Percent surface area of black non-viable tissue and yellow fibrinous slough was reduced to ≤ 10% in 18/21 (85·7%) and 12/21 (57·1%) wounds, respectively, after an average of 1-3 applications (3-9 days) of NPWTi-d with ROCF-CC. Preliminary evidence suggests that adjunctive use of NPWTi-d with ROCF-CC may help clean large, complex wounds when complete surgical debridement is not possible or appropriate and/or when areas of slough and non-viable tissue remain present on the wound surface.

A Suitable Option for Gustilo and Anderson Grade III Injury.

BACKGROUND The management of Gustilo and Anderson grade III injury remains difficult, particularly due to the incidence of wound infections, delayed fracture union, and traumatic extremity amputation. However, little data is available on delayed skin graft or flap reconstructions of Gustilo grade III injury, especially using new technologies of wound coverage, such as vacuum sealing drainage (VSD) combined with limited internal and/or external fixation. MATERIAL AND METHODS Between June 2008 and May 2013, we performed the VSD technique combined with limited internal and/or external fixation on 38 patients (22 males and 16 females, with a mean age of 36.5 years) with Gustilo and Anderson grade III injury. VSD was regularly changed and delayed skin grafts or flaps were used to cover the defect. Two patients were lost to follow-up, and the remaining 36 were available for evaluation. The complications, wound healing, infections, and bony union were assessed for a mean duration of 2.5 years (range, 1-4 years). RESULTS Complications were seen in 5 of the 36 cases: 2 cases had infection alone, 1 case had delayed union or nonunion, 1 case had infection and delayed union, and 1 case had wound necrosis, infection, and nonunion. VSD was regularly changed 2-6 times. Morphological appearance and functional recovery were satisfactory in all cases. CONCLUSIONS Using VSD before skin grafts or flaps coverage, combined with limited internal and/or external fixation, is a suitable option for Gustilo and Anderson grade III injury.

Vacuum Sealing Drainage Treatment Combined with Antibiotic-Impregnated Bone Cement for Treatment of Soft Tissue Defects and Infection.

BACKGROUND This study aimed to evaluate the combined effect of vacuum sealing drainage (VSD) and antibiotic-loaded bone cement on soft tissue defects and infection. MATERIAL AND METHODS This prospective non-blinded study recruited 46 patients with soft tissue defects and infection from January 2010 to May 2014 and randomly divided them into experimental and control groups (n=23). Patients in the experimental group were treated with VSD and antibiotic-loaded bone cement, while the patients in the control group were treated with VSD only. RESULTS In the experimental group, the wound was healed in 23 cases at 4 weeks postoperatively, of which direct suture was performed in 12 cases, and additional free flap transplantation or skin grafting was performed in 6 cases and 5 cases, respectively. No infection reoccurred in 1-year follow-up. In the control group, the wound was healed in 15 cases at 6 weeks postoperatively, of which direct suture was performed in 8 cases, and additional free flap transplantation or skin grafting was performed in 3 cases and 4 cases, respectively. In the other 8 cases the wound was healed at 8 weeks postoperatively. Infection reoccurred in 3 cases during the follow-up. The experimental group had significantly fewer VSD dressing renewals, shorter time needed until the wound was ready for surgery, shorter duration of antibiotic administration, faster wound healing, and shorter hospital stay than the control group (p<0.01). CONCLUSIONS The combination of VSD and antibiotic bone cement might be a better method for treatment of soft tissue defects and infection.

Achromobacter causing a thrombophlebitis and osteomyelitis combination: a rare cause.

Achromobacter xylosoxidans is a Gram-negative, aerobic bacillus, present in normal human flora of the skin and gastrointestinal tract. Infections due to Achromobacter are infrequent and have mostly been reported in immunocompromised patients. Rarely, however, the microorganism can cause soft tissue infections even in healthy subjects with a history of trauma. We report thrombophlebitis complicated with osteomyelitis secondary to Achromobacter in a 15-year-old girl with a history of purulent discharge from the ankle due to local trauma caused by tight fitting shoes.

Inhibition of Pseudomonas aeruginosa biofilm formation on wound dressings.

Chronic nonhealing skin wounds often contain bacterial biofilms that prevent normal wound healing and closure and present challenges to the use of conventional wound dressings. We investigated inhibition of Pseudomonas aeruginosa biofilm formation, a common pathogen of chronic skin wounds, on a commercially available biological wound dressing. Building on prior reports, we examined whether the amino acid tryptophan would inhibit P. aeruginosa biofilm formation on the three-dimensional surface of the biological dressing. Bacterial biomass and biofilm polysaccharides were quantified using crystal violet staining or an enzyme linked lectin, respectively. Bacterial cells and biofilm matrix adherent to the wound dressing were visualized through scanning electron microscopy. D-/L-tryptophan inhibited P. aeruginosa biofilm formation on the wound dressing in a dose dependent manner and was not directly cytotoxic to immortalized human keratinocytes although there was some reduction in cellular metabolism or enzymatic activity. More importantly, D-/L-tryptophan did not impair wound healing in a splinted skin wound murine model. Furthermore, wound closure was improved when D-/L-tryptophan treated wound dressing with P. aeruginosa biofilms were compared with untreated dressings. These findings indicate that tryptophan may prove useful for integration into wound dressings to inhibit biofilm formation and promote wound healing.

A taxonomically unique Acinetobacter strain with proteolytic and hemolytic activities recovered from a patient with a soft tissue injury.

A taxonomically unique bacterial strain, Acinetobacter sp. A47, has been recovered from several soft tissue samples from a patient undergoing reconstructive surgery owing to a traumatic amputation. The results of 16S rRNA, rpoB, and gyrB gene comparative sequence analyses showed that A47 does not belong to any of the hitherto-known taxa and may represent an as-yet-unknown Acinetobacter species. The recognition of this novel organism contributes to our knowledge of the taxonomic complexity underlying infections caused by Acinetobacter.

Impact of a novel, antimicrobial dressing on in vivo, Pseudomonas aeruginosa wound biofilm: quantitative comparative analysis using a rabbit ear model.

The importance of bacterial biofilms to chronic wound pathogenesis is well established. Different treatment modalities, including topical dressings, have yet to show consistent efficacy against wound biofilm. This study evaluates the impact of a novel, antimicrobial Test Dressing on Pseudomonas aeruginosa biofilm-infected wounds. Six-mm dermal punch wounds in rabbit ears were inoculated with 10(6) colony-forming units of P. aeruginosa. Biofilm was established in vivo using our published model. Dressing changes were performed every other day with either Active Control or Test Dressings. Treated and untreated wounds were harvested for several quantitative endpoints. Confirmatory studies were performed to measure treatment impact on in vitro P. aeruginosa and in vivo polybacterial wounds containing P. aeruginosa and Staphylococcus aureus. The Test Dressing consistently decreased P. aeruginosa bacterial counts, and improved wound healing relative to Inactive Vehicle and Active Control wounds (p < 0.05). In vitro bacterial counts were also significantly reduced following Test Dressing therapy (p < 0.05). Similarly, improvements in bacterial burden and wound healing were also achieved in polybacterial wounds (p < 0.05). This study represents the first quantifiable and consistent in vivo evidence of a topical antimicrobial dressing's impact against established wound biofilm. The development of clinically applicable therapies against biofilm such as this is critical to improving chronic wound care.

A pre-clinical evaluation of silver, iodine and Manuka honey based dressings in a model of traumatic extremity wounds contaminated with Staphylococcus aureus.

Prevention of extremity war wound infection remains a clinical challenge. Staphylococcus aureus is the most common pathogen in delayed infection. We hypothesised that choice of wound dressings may affect bacterial burden over 7 days reflecting the current practice of delayed primary closure of wounds within this timeframe. A randomised controlled trial of 3 commercially available dressings (Inadine(®) (Johnson & Johnson, NJ, USA), Acticoat(®) (Smith & Nephew, Hull, UK), Activon Tulle (Advancis Medical, Nottingham, UK)) was conducted in a rabbit model of contaminated forelimb muscle injury. A positive control group treated with antibiotics was included. Groups were compared to a saline soaked gauze control. The primary outcome was a statistically significant reduction (p < 0.05) in tissue S. aureus at 7 days post-injury. Secondary outcome measurements included bacteraemias, observational data, whole blood determination, ELISA for plasma biomarkers, PCR array analysis of wound healing gene expression and muscle/lymph node histopathology. Antibiotic, Inadine and Acticoat groups had statistically significant lower bacterial counts (mean 7.13 [95% CI 0.00-96.31]×10(2); 1.66 [0.94-2.58]×10(5); 8.86 [0.00-53.35]×10(4)cfu/g, respectively) and Activon Tulle group had significantly higher counts (2.82 [0.98-5.61]×10(6)cfu/g) than saline soaked gauze control (7.58 [1.65-17.83]×10(5)cfu/g). There were no bacteraemias or significant differences in observational data or whole blood determination. There were no significant differences in muscle/loss or pathology and lymph node cross-sectional area or morphology. There were some significant differences between treatment groups in the plasma cytokines IL-4, TNFα and MCP-1 in comparison to the control. PCR array data demonstrated more general changes in gene expression in the muscle tissue from the Activon Tulle group than the Inadine or Acticoat dressings with a limited number of genes showing significantly altered expression compared to control. This study has demonstrated that both Acticoat(®) and Inadine(®) dressings can reduce the bacteria burden in a heavily contaminated soft tissue wound and so they may offer utility in the clinical setting particularly where surgical treatment is delayed.

Prospective randomised controlled trial of nanocrystalline silver dressing versus plain gauze as the initial post-debridement management of military wounds on wound microbiology and healing.

INTRODUCTION: Recent conflicts have been characterised by the use of improvised explosive devices causing devastating injuries, including heavily contaminated wounds requiring meticulous surgical debridement. After being rendered surgical clean, these wounds are dressed and the patient transferred back to the UK for on-going treatment. A dressing that would prevent wounds from becoming colonised during transit would be desirable. The aim of this study was to establish whether using nanocrystalline silver dressings, as an adjunct to the initial debridement, would positively affect wound microbiology and wound healing compared to standard plain gauze dressings. METHODS: Patients were prospectively randomised to receive either silver dressings, in a nanocrystalline preparation (Acticoat™), or standard of care dressings (plain gauze) following their initial debridement in the field hospital. On repatriation to the UK microbiological swabs were taken from the dressing and the wound, and an odour score recorded. Wounds were followed prospectively and time to wound healing was recorded. Additionally, patient demographic data were recorded, as well as the mechanism of injury and Injury Severity Score. RESULTS: 76 patients were recruited to the trial between February 2010 and February 2012. 39 received current dressings and 37 received the trial dressings. Eleven patients were not swabbed. There was no difference (p=0.1384, Fishers) in the primary outcome measure of wound colonisation between the treatment arm (14/33) and the control arm (20/32). Similarly time to wound healing was not statistically different (p=0.5009, Mann-Whitney). Wounds in the control group were scored as being significantly more malodorous (p=0.002, Mann-Whitney) than those in the treatment arm. CONCLUSIONS: This is the first randomised controlled trial to report results from an active theatre of war. Performing research under these conditions poses additional challenges to military clinicians. Meticulous debridement of wounds remains the critical determinant in wound healing and infection and this study did not demonstrate a benefit of nanocrystaline silver dressing in respect to preventing wound colonisation or promoting healing, these dressings do however seem to significantly reduce the unpleasant odour commonly associated with battlefield wounds.