Are topical antimicrobials effective against bacteria that are highly resistant to systemic antibiotics?

Predictors of Sepsis and Sepsis-related Mortality in Critically Ill Burn Patients: A Single Tertiary Care Center Experience

Background

Clinical diagnosis of sepsis is challenging, emphasizing the importance of regular bacterial surveillance, and tailored antimicrobial therapy. This study aims to elucidate the predictors of sepsis in critically ill burn patients.

Methods

A retrospective analysis was conducted on patients admitted to the burn intensive care unit between 2016 and 2022. Demographics, type of burn, total body surface area (TBSA), presence of inhalation injury, mortality, sepsis, deep vein thrombosis, pulmonary embolism, pneumonia, cultures, and laboratory findings were collected. Descriptive statistics and survival analysis were used to analyze trends during the 7-year period.

Results

The study encompassed 196 participants. Among patient factors, men constituted 73.4% (n = 102) of those without sepsis and 86.0% (n = 49) with sepsis, with an association between sepsis and lower age (34 versus 41 years) as well as larger TBSA (41.1% versus 17.3%). Inhalation injury was a significant predictor of sepsis [35.1% (n = 20) versus 11.6% (n = 16)]. Mortality was higher in sepsis cases [17.5% (n = 10) versus 2.9% (n = 4)], as well as positive blood cultures [47.4% (n = 27) versus 2.2% (n = 3)], positive wound cultures [71.9% (n = 41) versus 12.2% (n = 17)], and positive fungal cultures [12.3% (n = 7) versus 0% (n = 0)]. Multivariable analysis identified age and TBSA as significant predictors of sepsis (P = 0.025, P < 0.001).

Conclusions

Age, TBSA affected emerge as a strong risk factor for sepsis among critically ill burn patients. It underscores the need for vigilant monitoring to improve outcomes and reduce sepsis-related mortality.

Topical Drug Delivery in the Treatment of Skin Wounds and Ocular Trauma Using the Platform Wound Device

Topical treatment of injuries such as skin wounds and ocular trauma is the favored route of administration. Local drug delivery systems can be applied directly to the injured area, and their properties for releasing therapeutics can be tailored. Topical treatment also reduces the risk of adverse systemic effects while providing very high therapeutic concentrations at the target site. This review article highlights the Platform Wound Device (PWD) (Applied Tissue Technologies LLC, Hingham, MA, USA) for topical drug delivery in the treatment of skin wounds and eye injuries. The PWD is a unique, single-component, impermeable, polyurethane dressing that can be applied immediately after injury to provide a protective dressing and a tool for precise topical delivery of drugs such as analgesics and antibiotics. The use of the PWD as a topical drug delivery platform has been extensively validated in the treatment of skin and eye injuries. The purpose of this article is to summarize the findings from these preclinical and clinical studies.

Review of History of Basic Principles of Burn Wound Management

Thermal energy is an essential and useful resource to humans in modern society. However, a consequence of using heat carelessly is burns. Burn injuries have various causes, such as exposure to flame, radiation, electrical, and chemical sources. In this study, we reviewed the history of burn wound care while focusing on the basic principles of burn management. Through this review, we highlight the need for careful monitoring and customization when treating burn victims at each step of wound care, as their individual needs may differ. We also propose that future research should focus on nanotechnology-based skin grafts, as this is a promising area for further improvement in wound care.

Fabrication of moxifloxacin HCl-loaded biodegradable chitosan nanoparticles for potential antibacterial and accelerated cutaneous wound healing efficacy

AIM

This work aims to formulate topical hybrid gel containing chitosan-coated moxifloxacin (MXF) HCl nanoparticles (NPs) with enhanced antibacterial and healing activity.

METHODS

MXF HCl NPs prepared by the ionic gelation method were loaded onto a hybrid chitosan carbomer gel. Size analysis of the prepared NPs was performed using SEM and Zeta-sizer. Further characterisation was done using Fourier transforms infra-red spectroscopy (FTIR), X-ray diffraction (XRD), and Thermogravimetric analysis (TGA). Prepared gel was evaluated for its in vitro drug release, biocompatibility, antibacterial activity, and stability studies under storage conditions. In-vivo wound healing was measured by observing percentage reduction in wound.

RESULTS

NPs have 359 ± 79 nm mean particle size, 31.01 mV zeta potential with 0.008 polydispersity index (PD1), 63.5% drug entrapment and 83 ± 3.5% drug release at pH 5.5. Hybrid chitosan carbomer gel showed good biocompatibility, antibacterial, in-vivo wound healing properties and stable properties.

CONCLUSIONS

NP-loaded hybrid gel can be an effective treatment for acute and challenged topical wounds.

Burn Wound Colonization, Infection, and Sepsis

Background: Infection is a major cause of morbidity and mortality among burn patients, and it is important to understand the progression of wound colonization to wound infection to systemic sepsis. Methods: After a review of the literature we describe the clinical characteristics of burn wound colonization, infection, and sepsis, and conclude with best practices to decrease these complications. Results: Burn wounds are initially sterile after the thermal insult but become colonized by gram-positive organisms and subsequently by gram-negative organisms. Some populations are especially susceptible to initial or subsequent colonization by drug-resistant organisms. An increase in fungal colonization has been observed because of the widespread use of topical antibiotic agents. Male gender, older age, lower extremity burn, scald burn, full-thickness burn, delay in treatment, and pre-existing diabetes place patients at increased risk of infection. These infections range from cellulitis that requires systemic antibiotic agents, to invasive burn wound infection that requires prompt treatment with antibiotic agents and excision. Fungal wound infections pose a special challenge and cause substantial morbidity. Infection that leads to systemic sepsis is difficult to define in burn patients because of the body's compensatory hypermetabolic response to the burn injury. Potential sources of sepsis include wound infections and common nosocomial infections. The American Burn Association Sepsis criteria, defined in 2007, has demonstrated poor specificity for identifying sepsis and septic shock. The best approach to decrease wound infections is prevention. Practices that have been beneficial include isolation rooms, handwashing, appropriate wound care, early excision and grafting, antibiotic stewardship, and nutritional support. Conclusions: A burn patient remains at a substantial risk of wound infection despite advances in care. A burn care provider must understand the natural progression of colonization to infection to sepsis, and the multidisciplinary approach to wound care to limit the morbidity and mortality from these infectious.

Efficacy of Topical Antimicrobial Agents Against Bacterial Isolates From Burn Wounds

Topically applied antimicrobials are key to the prevention of infection and mortality in the acute burn population. The purpose of this study was to determine the in vitro effectiveness of commercially available topical antimicrobials, as well as topical preparations that were compounded in our burn care institution. One-hundred twenty microorganisms were tested against these topical antimicrobials and in vitro effectiveness was observed. Results showed that compounded preparations of 1:1:1 + Double Antibiotic (1 part bacitracin: 1 part silver sulfadiazine: 100,000 units/g nystatin + 5 mg/g neomycin sulfate + 500 units/g polymyxin B) and 3:1 + Double Antibiotic (3 part bacitracin: 1 part silver sulfadiazine + 5mg/g neomycin sulfate + 500 units/g polymyxin B) were effective against 100% of the isolates tested. Other topical agents showed moderate effectiveness, thus demonstrating the need for multiple topical agents to reach a broad spectrum of microorganisms. However, the development of topical antimicrobial resistance needs further study.

Risk and clinical impact of bacterial resistance/susceptibility to silver-based wound dressings: a systematic review

Objective:

To perform a systematic review of the literature on bacterial resistance, tolerance and susceptibility of silver within the context of wound therapy using silver-based dressings.

Methods:

A literature search was carried out using PubMed, Embase and Cochrane Library databases, the focus was whether results from microbiological experimental in vitro tests with reference strains and clinical wound isolates are reflected in clinical practice with regards to their ‘resistance’ profiles, comparable with those observed for antibiotics. The search results were allocated to six categories: resistance and resistance mechanism, in vitro tests with standard strains and wound isolates, prevalence and incidence, impact on clinical practice and impact on antibiotic therapy as well as reviews, expert opinions and consensus.

Results:

Based on all findings of the literature, it cannot be confirmed that a related clinical resistance to silver-ions in silver-based dressings has clinical impact, although endogenous and exogenous genetic resistance patterns have been described and intensively investigated. A translation of these genetic resistance-expression structures to phenotypic appearances, similar to those known for antibiotics, has not been demonstrated for silver in the literature.

Conclusion:

It can be concluded that there is no definitive evidence available and further studies should be conducted.

Dakin's solution in the treatment of severe diabetic foot infections

Acute necrotising diabetic foot (DF) infections are common, costly, and do not infrequently result in debilitating major lower-extremity amputations. Dakin's solution is a long-standing topical antiseptic that has shown benefit in this clinical setting, but its use is undermined by a presumed risk of cytotoxicity. In this single-centre case series, we retrospectively evaluated 24 patients with severe necrotising DF infections treated with a cyclical instillation of Dakin's solution at a referral multidisciplinary DF unit. Most patients achieved favourable outcomes in infection control and limb salvage, with only one patient (4.2%) requiring a major (at or above-the-ankle) amputation. The mean time to complete or near-complete wound granulation was 5.4 weeks. Of the 12 patients who completed 12 or more months of longitudinal follow up, only 2 (12.2%) had a wound recurrence. In this severe DF infection patient cohort, Dakin's solution led to a clinically meaningful improvement. No remarkable impairment in the wound-healing process was observed.

Which Method Is Better to Provide Wound Healing in Fournier Gangrene: Dakin Solution or Conventional Antiseptic Dressings? A Retrospective Study

Fournier gangrene is described as necrotizing fasciitis involving the genital, perineal, and perianal area. Early surgical debridement of necrotic tissues, topical therapy, and antibiotics are fundamental in the treatment of Fournier gangrene. We aimed to compare the effects of Dakin solution and povidone iodine solution on patient outcomes by using the Fournier gangrene severity index (FGSI). The demographic data, comorbid diseases, local therapeutic interventions, FGSI, necessity of diverting colostomy or orchiectomy, hospitalization time, number of debridements, complications, and outcomes of 57 patients with Fournier gangrene were retrospectively analyzed. A total of 47 of 57 patients (82.5%) were male, and 10 patients (17.5%) were female, with a mean age of 62.3 ± 13.8 years (range, 27–85 years). The survivors were significantly younger than the nonsurvivors. The mean FGSI score was 4 (range, 1–9) in survivors, and mean FGSI score was 9 (range, 6–10) in nonsurvivors. FGSI score was significantly higher in the mortality group. The median hospital stay was 13 days (range, 3–34 days) in the Dakin solution group and 20 days (range, 1–41 days) in the povidone iodine group. Overall mortality rate was 17.5%. Advanced age had a statistically significant effect on mortality. The hospitalization time was significantly shorter in the Dakin solution group, and use of Dakin solution decreased the number of debridements. Dakin solution has favorable effects on hospital stay and the necessity of multiple debridements. Dakin solution seems to be a good and cost-effective choice for treatment in local wound healing.

2.5% Mafenide Acetate: A Cost-Effective Alternative to the 5% Solution for Burn Wounds

Mafenide acetate is an antimicrobial agent used to decrease the bacterial load for burn wounds. The 5% solution is more commonly used yet double the cost of its 2.5% counterpart. This study aims to evaluate outcomes and cost associated with the use of 2.5 vs 5% mafenide acetate formulation in the adult burn population. Adult patients (≥18 years) receiving 2.5% mafenide acetate during an 11-month period between 2014 and 2015, corresponding to a policy change in favor of the use of 2.5% mafenide acetate, were queried. Historical controls, patients receiving 5% mafenide acetate, were also reviewed during an 11-month period between 2013 and 2014. A retrospective review was performed comparing wound infection rate, bacteremia, sepsis, pneumonia, duration of mafenide therapy, length of hospital stay, mortality, and cost. A total of 54 and 65 patients received 2.5 and 5% mafenide acetate, respectively. There was no difference in wound infection, bacteremia, sepsis, pneumonia, duration of treatment, and mortality between the two groups. No adverse events occurred in either group directly related to mafenide. Candida and Staph species were the two most common isolates in the 2.5% group, whereas Pseudomonas and Staph species were the most common in the 5% arm. The mean cost of 2.5% mafenide therapy was $1494.92 compared with $3741.39 for 5% mafenide acetate. The 2.5% concentration demonstrates to be an equally efficacious and cost-effective alternative to the 5% concentration. Burn centers should consider the use of the more dilute preparation for burn wound infection prophylaxis as it may reduce the cost without compromising patient safety.

Burn Wound Healing and Tissue Engineering

In 2016 the American Burn Association held a State of the Science conference to help identify burn research priorities for the next decade. The current paper summarizes the work of the sub-committee on Burn Wound Healing and Tissue Engineering. We first present the priorities in wound healing research over the next 10 years. We then summarize the current state of the science related to burn wound healing and tissue engineering including determination of burn depth, limiting burn injury progression, eschar removal, management of microbial contamination and wound infection, measuring wound closure, accelerating wound healing and durable wound closure, and skin substitutes and tissue engineering. Finally, a summary of the round table discussion is presented.

Functionalization of bacterial cellulose wound dressings with the antimicrobial peptide ε-poly-L-Lysine

Wound dressings based on bacterial cellulose (BC) can form a soft and conformable protective layer that can stimulate wound healing while preventing bacteria from entering the wound. Bacteria already present in the wound can, however, thrive in the moist environment created by the BC dressing which can aggravate the healing process. Possibilities to render the BC antimicrobial without affecting the beneficial structural and mechanical properties of the material would hence be highly attractive. Here we present methods for functionalization of BC with ε-poly-L-Lysine (ε-PLL), a non-toxic biopolymer with broad-spectrum antimicrobial activity. Low molecular weight ε-PLL was cross-linked in pristine BC membranes and to carboxymethyl cellulose functionalized BC using carbodiimide chemistry. The functionalization of BC with ε-PLL inhibited growth of S. epidermidis on the membranes but did not affect the cytocompatibility to cultured human fibroblasts as compared to native BC. The functionalization had no significant effects on the nanofibrous structure and mechanical properties of the BC. The possibility to functionalize BC with ε-PLL is a promising, green and versatile approach to improve the performance of BC in wound care and other biomedical applications.

Retroperitoneal Necrotizing Fasciitis from Fournier's Gangrene in an Immunocompromised Patient

INTRODUCTION

Necrotizing fasciitis (NF) is a devastating soft tissue disease causing fulminant clinical deterioration, and extension into the retroperitoneum has a high mortality rate. This disease process demands a strong clinical suspicion for early identification which must be coupled with frequent wide surgical debridements and intravenous antibiotics for improved outcomes. Various clinical risk factors may render a weakness in the patient's immune status including diabetes mellitus, chronic renal failure, obesity, and autoimmune disorders, such as a human immunodeficiency virus (HIV) infection.

CASE REPORT

A 55-year-old male presented with hypotension requiring a large intravenous fluid resuscitation and vasopressors. He was diagnosed with the human immunodeficiency virus upon presentation. A computerized tomographic scan revealed air and fluid in the perineum and pelvis, ascending into the retroperitoneum. Multiple surgical debridements to his perineum, deep pelvic structures, and retroperitoneum were completed. After colostomy placement, antibiotic administration, and wound care, he was closed using split-thickness skin grafting.

CONCLUSION

NF is a sinister and fulminant disease requiring prompt diagnosis and surgical intervention. The best chance for survival occurs with emergent surgical debridement and appropriate intravenous antibiotics. While retroperitoneal NF is consistent with uniformly poor outcomes, patients are best treated in an American Burn Association-verified burn center.

Topical antimicrobial agents for pediatric burns

While topical antimicrobial agents are indicated for most if not all burn wounds, the choice of a topical agent must consider many factors such as the wound depth, anticipated time to healing, need for surgical intervention, and the known cytotoxicity of the agent. Especially relevant to the pediatric burn patient are the antimicrobial agent’s properties related to causing pain or irritation and the required frequency of application and dressings. This article will discuss the general principles surrounding the use of topical antimicrobials on burn wounds and will review the most common agents currently in use.

Antimicrobial peptide Epinecidin-1 promotes complete skin regeneration of methicillin-resistant Staphylococcus aureus-infected burn wounds in a swine model

This report shows that the antimicrobial peptide (AMP) Epinecidin-1 (Epi-1) efficiently heals MRSA-infected heat burn injuries and provides protection from infection in a pig model. The presence of an optimal level of Epi-1 induces cell proliferation by promoting cell cycle progression through an increase in S-phase cells. Epi-1 also induces proliferation to cover the wounded region in an in vitro cell proliferation assay using immortalized human epithelial HaCaT cells. Next, the in vivo wound healing efficiency of Epi-1 was tested in heat-burned pig skin infected with MRSA under in vivo conditions. Treatment of the injury with Epi-1 for 1 h at six hours post-infection completely healed the wound within 25 days. Conversely, the injury in the untreated control was not healed 25 days post-infection. Histological staining of wound sections with H&E showed that Epi-1 enhanced vascularization and increased epithelial activities in the wound region. Neutrophil recruitment to the wounded region in the Epi-1-treated sections was visualized by Giemsa staining. Additionally, Masson's trichrome staining of wound sections confirmed that Epi-1 enhanced extracellular collagen compound formation. The induction of sepsis-associated blood C-reactive protein (CRP) and the pro-inflammatory cytokine IL-6 in response to MRSA infection was also suppressed in pigs that received Epi-1. Taken together, the results demonstrate that the biomaterial Epi-1 heals wounds through increasing epithelial cell proliferation, vascularization, and the formation of collagen and controls MRSA infection-mediated sepsis in pigs.

Topical antimicrobial agents for treating foot ulcers in people with diabetes

BACKGROUND

People with diabetes are at high risk for developing foot ulcers, which often become infected. These wounds, especially when infected, cause substantial morbidity. Wound treatments should aim to alleviate symptoms, promote healing, and avoid adverse outcomes, especially lower extremity amputation. Topical antimicrobial therapy has been used on diabetic foot ulcers, either as a treatment for clinically infected wounds, or to prevent infection in clinically uninfected wounds.

OBJECTIVES

To evaluate the effects of treatment with topical antimicrobial agents on: the resolution of signs and symptoms of infection; the healing of infected diabetic foot ulcers; and preventing infection and improving healing in clinically uninfected diabetic foot ulcers.

SEARCH METHODS

We searched the Cochrane Wounds Specialised Register, CENTRAL, Ovid MEDLINE, Ovid MEDLINE (In-Process & Other Non-Indexed Citations), Ovid Embase, and EBSCO CINAHL Plus in August 2016. We also searched clinical trials registries for ongoing and unpublished studies, and checked reference lists to identify additional studies. We used no restrictions with respect to language, date of publication, or study setting.

SELECTION CRITERIA

We included randomised controlled trials conducted in any setting (inpatient or outpatient) that evaluated topical treatment with any type of solid or liquid (e.g., cream, gel, ointment) antimicrobial agent, including antiseptics, antibiotics, and antimicrobial dressings, in people with diabetes mellitus who were diagnosed with an ulcer or open wound of the foot, whether clinically infected or uninfected.

DATA COLLECTION AND ANALYSIS

Two review authors independently performed study selection, 'Risk of bias' assessment, and data extraction. Initial disagreements were resolved by discussion, or by including a third review author when necessary.

MAIN RESULTS

We found 22 trials that met our inclusion criteria with a total of over 2310 participants (one study did not report number of participants). The included studies mostly had small numbers of participants (from 4 to 317) and relatively short follow-up periods (4 to 24 weeks). At baseline, six trials included only people with ulcers that were clinically infected; one trial included people with both infected and uninfected ulcers; two trials included people with non-infected ulcers; and the remaining 13 studies did not report infection status.Included studies employed various topical antimicrobial treatments, including antimicrobial dressings (e.g. silver, iodides), super-oxidised aqueous solutions, zinc hyaluronate, silver sulphadiazine, tretinoin, pexiganan cream, and chloramine. We performed the following five comparisons based on the included studies: Antimicrobial dressings compared with non-antimicrobial dressings: Pooled data from five trials with a total of 945 participants suggest (based on the average treatment effect from a random-effects model) that more wounds may heal when treated with an antimicrobial dressing than with a non-antimicrobial dressing: risk ratio (RR) 1.28, 95% confidence interval (CI) 1.12 to 1.45. These results correspond to an additional 119 healing events in the antimicrobial-dressing arm per 1000 participants (95% CI 51 to 191 more). We consider this low-certainty evidence (downgraded twice due to risk of bias). The evidence on adverse events or other outcomes was uncertain (very low-certainty evidence, frequently downgraded due to risk of bias and imprecision). Antimicrobial topical treatments (non dressings) compared with non-antimicrobial topical treatments (non dressings): There were four trials with a total of 132 participants in this comparison that contributed variously to the estimates of outcome data. Evidence was generally of low or very low certainty, and the 95% CIs spanned benefit and harm: proportion of wounds healed RR 2.82 (95% CI 0.56 to 14.23; 112 participants; 3 trials; very low-certainty evidence); achieving resolution of infection RR 1.16 (95% CI 0.54 to 2.51; 40 participants; 1 trial; low-certainty evidence); undergoing surgical resection RR 1.67 (95% CI 0.47 to 5.90; 40 participants; 1 trial; low-certainty evidence); and sustaining an adverse event (no events in either arm; 81 participants; 2 trials; very low-certainty evidence). Comparison of different topical antimicrobial treatments: We included eight studies with a total of 250 participants, but all of the comparisons were different and no data could be appropriately pooled. Reported outcome data were limited and we are uncertain about the relative effects of antimicrobial topical agents for each of our review outcomes for this comparison, that is wound healing, resolution of infection, surgical resection, and adverse events (all very low-certainty evidence). Topical antimicrobials compared with systemic antibiotics : We included four studies with a total of 937 participants. These studies reported no wound-healing data, and the evidence was uncertain for the relative effects on resolution of infection in infected ulcers and surgical resection (very low certainty). On average, there is probably little difference in the risk of adverse events between the compared topical antimicrobial and systemic antibiotics treatments: RR 0.91 (95% CI 0.78 to 1.06; moderate-certainty evidence - downgraded once for inconsistency). Topical antimicrobial agents compared with growth factor: We included one study with 40 participants. The only review-relevant outcome reported was number of ulcers healed, and these data were uncertain (very low-certainty evidence).

AUTHORS' CONCLUSIONS

The randomised controlled trial data on the effectiveness and safety of topical antimicrobial treatments for diabetic foot ulcers is limited by the availability of relatively few, mostly small, and often poorly designed trials. Based on our systematic review and analysis of the literature, we suggest that: 1) use of an antimicrobial dressing instead of a non-antimicrobial dressing may increase the number of diabetic foot ulcers healed over a medium-term follow-up period (low-certainty evidence); and 2) there is probably little difference in the risk of adverse events related to treatment between systemic antibiotics and topical antimicrobial treatments based on the available studies (moderate-certainty evidence). For each of the other outcomes we examined there were either no reported data or the available data left us uncertain as to whether or not there were any differences between the compared treatments. Given the high, and increasing, frequency of diabetic foot wounds, we encourage investigators to undertake properly designed randomised controlled trials in this area to evaluate the effects of topical antimicrobial treatments for both the prevention and the treatment of infection in these wounds and ultimately the effects on wound healing.

Antibiotic treatment of biofilm infections

Bacterial biofilms are associated with a wide range of infections, from those related to exogenous devices, such as catheters or prosthetic joints, to chronic tissue infections such as those occurring in the lungs of cystic fibrosis patients. Biofilms are recalcitrant to antibiotic treatment due to multiple tolerance mechanisms (phenotypic resistance). This causes persistence of biofilm infections in spite of antibiotic exposure which predisposes to antibiotic resistance development (genetic resistance). Understanding the interplay between phenotypic and genetic resistance mechanisms acting on biofilms, as well as appreciating the diversity of environmental conditions of biofilm infections which influence the effect of antibiotics are required in order to optimize the antibiotic treatment of biofilm infections. Here, we review the current knowledge on phenotypic and genetic resistance in biofilms and describe the potential strategies for the antibiotic treatment of biofilm infections. Of note is the optimization of PK/PD parameters in biofilms, high-dose topical treatments, combined and sequential/alternate therapies or the use antibiotic adjuvants.

Dakin's solution: is there a place for it in the 21st century?

Dakin's solution (DS) is a time-honoured antiseptic that still remains part of the wound care armamentarium. In spite of its cytotoxicity, some question its use in the current era. We report the case of a 52-year-old diabetic woman who was admitted for sepsis because of a severely infected diabetic foot. Urgent surgical drainage and debridement left a 9 × 9-cm deep, complex, infected wound with both bone and tendon involvement. Treatment with local negative pressure was unsuccessful. DS was regularly instilled through a tube left in the wound dressing. A marked improvement was observed with this strategy as the wound bed was much cleaner and fully granulated after 6 weeks. No adverse effects were noted. This case debunks the myth that topical antiseptics necessarily impair wound healing. DS can still be considered an option for difficult-to-treat, complex and heavily infected wounds.

Adaptive Cross-Resistance to Aminoglycoside Antibiotics in Pseudomonas aeruginosa Induced by Topical Dosage of Neomycin

BACKGROUND

Topical antimicrobial formulations containing neomycin are commonly used to prevent and treat burn infections. However, Pseudomonas aeruginosa shows rapid acquisition of adaptive resistance to neomycin. This study aimed to evaluate the survival of P. aeruginosa during exposure to neomycin at high concentrations comparable to those used in topical formulations, and to investigate the effect of adaptive resistance to neomycin on the susceptibility to other aminoglycosides.

METHODS

Strain IID1130 [neomycin minimal inhibitory concentration (MIC) = 4 µg/ml] was incubated on an agar medium containing neomycin at high concentrations (8-4,096 µg/ml), and growing colonies were macroscopically observed. Acquisition of adaptive resistance was examined for 5 P. aeruginosa strains. Cells were sequentially passaged on agar medium containing neomycin with step-wise increased concentrations (8-2,048 µg/ml). To assess reversion of antibiotic susceptibility, the resulting colonies were repeatedly subcultured on antibiotic-free agar plates.

RESULTS

Growing IID1130 colonies were macroscopically detected on a neomycin-containing (2,048 µg/ml) agar plate for 48 h. These cells showed increasing MIC for not only neomycin, but also gentamicin and amikacin; the MIC values were occasionally higher than the breakpoints. When the adapted cells were subcultured on antibiotic-free agar, several passages were required for reversion of susceptibility.

CONCLUSIONS

Our findings suggest that P. aeruginosa can survive in the presence of neomycin with a concentration typically used in topical dosage forms, and that the acquired adaptive resistance is persistent and is accompanied by cross-resistance to other aminoglycosides.

Hydrofiber Dressing Saturated With Mafenide Acetate Extends the Duration of Antimicrobial Activity

Mafenide acetate is used in some burn wounds for its ability to penetrate eschar but requires frequent uncomfortable dressing changes for its application. The authors hypothesize that hydrofiber dressings will hold mafenide acetate solution for an extended period of time and maintain antimicrobial activity longer than traditional gauze, thus possibly obviating the need for frequent dressing changes. Four experimental arms included: 1) hydrofiber, stored on a dry well plate as control, 2) gauze saturated with 2.5% mafenide acetate, stored on nonsterile porcine skin, 3) hydrofiber saturated with mafenide acetate, stored on dry well plate, and 4) hydrofiber saturated with mafenide acetate, stored on nonsterile porcine skin. At 0, 24, 48, and 72 hours, a 1-cm disk was cut from the dressing sheet of each study arm, placed on agar plates seeded with Staphylococcus aureus and Pseudomonas aeruginosa, and incubated for 24 hours, and the zone of inhibition was measured. A zone of 2 mm or greater was indicative of susceptibility. Each arm of the experiment was performed four times to demonstrate reproducibility. Plain hydrofiber (control) demonstrated no zone of inhibition at any time point, thereby possessing no antimicrobial activity alone. Gauze saturated with mafenide acetate did not reliably demonstrate antimicrobial activity beyond 0 hours. Hydrofiber saturated with mafenide acetate, whether stored on a dry well plate or nonsterile porcine skin, consistently possessed sustained antimicrobial activity as demonstrated by zones of inhibition greater than 2 mm to both S. aureus and P. aeruginosa. Mafenide acetate-soaked hydrofiber dressings stay moist and maintain antimicrobial activity against S. aureus and P. aeruginosa for at least 72 hours without repeated soaks.

Hypertrophic scarring: the greatest unmet challenge after burn injury

Improvements in acute burn care have enabled patients to survive massive burns that would have once been fatal. Now up to 70% of patients develop hypertrophic scars after burns. The functional and psychosocial sequelae remain a major rehabilitative challenge, decreasing quality of life and delaying reintegration into society. Approaches to optimise healing potential of burn wounds use targeted wound care and surgery to minimise the development of hypertrophic scarring. Such approaches often fail, and modulation of the established scar is continued although the optimal indication, timing, and combination of therapies have yet to be established. The need for novel treatments is paramount, and future efforts to improve outcomes and quality of life should include optimisation of wound healing to attenuate or prevent hypertrophic scarring, well-designed trials to confirm treatment efficacy, and further elucidation of molecular mechanisms to allow development of new preventive and therapeutic strategies.

Synthetic lipopeptides as potential topical therapeutics in wound and skin care: in vitro studies of permeation and skin cells behaviour

Wound healing is an extraordinarily complicated process associating with the cell aging, slowing down of cell renewal mechanism and even loss of protective function to environmentally induced oxidative stress.

Bacterial profile and antimicrobial susceptibility pattern of isolates among burn patients at Yekatit 12 Hospital Burn Center, Addis Ababa, Ethiopia

Background

Infection is a common cause of morbidity and mortality in burn patients. Clinical diagnosis of bacteremia and/or sepsis in burn patients is difficult for a number of reasons. It could be symptomatic and/or asymptomatic as a result of immune deficiency secondary to thermal injury.

Methods

A cross sectional study was conducted at Yekatit 12 Hospital Burn Center. Blood specimen and wound swab were collected from burn patients and were cultured by conventional method. Sensitivity/susceptibility pattern of the isolates was determined by disc diffusion method. Some of the risk factors of bacteremia like prior antibiotic use and total body surface area burn were also determined.

Results

Fifty patients were enrolled in the study of whom 21(42%) were found bacteremic. Five different bacteria were isolated from blood specimen. Coagulase negative Staphylococci, 9(42.8%), S. aureus, 8(38.2%), Bacillus spps, 2(9.52%), K. pneumoniae, 1(4.8%), and P. aeruginosa, 1(4.8%), were frequent isolates. From wound swab, S. aureus, (34.04%), and P. aeruginosa, (31.8%), were predominant. Antimicrobial resistance was observed for Ampicillin, (77.4%), Doxycycline, (74.0), Nalidixic acid, (70.5%), Penicillin G, (68.2%), and tetracycline, (67.5%). Total body surface area of burn ≥ 15% was found as a risk factor for bacteremia.

Conclusion

Bacteremia was detected at a rate of 42% among burn patients. Frequent isolates were S. aureus, (34.04%), and P. aeruginosa, (31.8%). About 82.16% of the isolates showed multiple resistances. In light of our findings, regular antibiotic resistance test has to be done for each patient in order to select an appropriate antimicrobial agent.

Using skin for drug delivery and diagnosis in the critically ill

Skin offers easy access, convenience and non-invasiveness for drug delivery and diagnosis. In principle, these advantages of skin appear to be attractive for critically ill patients given potential difficulties that may be associated with oral and parenteral access in these patients. However, the profound changes in skin physiology that can be seen in these patients provide a challenge to reliably deliver drugs or provide diagnostic information. Drug delivery through skin may be used to manage burn injury, wounds, infection, trauma and the multisystem complications that rise from these conditions. Local anaesthetics and analgesics can be delivered through skin and may have wide application in critically ill patients. To ensure accurate information, diagnostic tools require validation in the critically ill patient population as information from other patient populations may not be applicable.

Wound care: biofilm and its impact on the latest treatment modalities for ulcerations of the diabetic foot

Biofilm is an increasingly important topic of discussion in the care of the chronic diabetic foot wound. Treatment modalities have focused on biofilm reduction or eradication through debridement techniques, topical therapies, negative pressure therapy, and ultrasound. In addition, advanced wound healing modalities, such as bioengineered alternative tissues, require optimal wound bed preparation with specific consideration of biofilm reduction before their application. Although fundamental principles of diabetic wound care still apply, critical thought must be given to biofilm before implementing a treatment plan for the closure of these complex wounds.

The burn wound inflammatory response is influenced by midazolam

Burn patients requiring hospitalization are often treated for anxiety with benzodiazepines (BDZs). Benzodiazepines are reported to influence immune system function. Immune system alterations are a major cause of burn-induced mortality. We wanted to determine whether the BDZ, midazolam given daily at an anxiolytic dose, had any influence on the burn injury-induced inflammatory response in the blood and wound. Mice received a 15% total body surface area flame burn and received either midazolam 1 mg/kg i.p. or saline 0.1 ml daily. Blood and skin wounds were harvested 24 h after injection on post-burn day 2, 3, 7, or 8. Mice treated with midazolam had significantly lower serum IL-1β (p=0.002), TNF-α (p=0.002), IL-6 (p=0.016), IL-10 (p=0.009), and TGF-β (p=0.004) than saline-treated mice, with little impact on serum chemokine levels. In the wound, TNF-α and IL-10 were the only cytokines significantly influenced by the drug, being lower (p=0.018) and higher (p=0.006), respectively. The chemokines in the wound influenced significantly by midazolam were MIP-1α, MIP-1β, and MIP-2 while MCP-1 and KC were not. There were more inflammatory cells at the burn wound margin in midazolam-treated mice on post-burn day 3. Although serum nitrate/nitrite was significantly increased by midazolam (p=0.03), both eNOS and iNOS mRNA expression in the wound were similar to the saline group. We found that midazolam given daily after burn injury significantly influenced the inflammatory response. The clinical implications of these findings on wound healing and shock following burn injury, especially larger burns, deserve further investigation.

Comparison of the antibacterial effect of silver sulfadiazine 1%, mupirocin 2%, Acticoat and octenidine dihydrochloride in a full-thickness rat burn model contaminated with multi drug resistant Acinetobacter baumannii

In this study, our aim is to compare the efficacy of different topical antibacterial agents in a rat model contaminated with a multi drug resistant (MDR) standard Acinetobacter baumannii strain. The study was carried out on 40 Sprague-Dawley rats of 250-300 g each. For the purposes of this study, the rats were divided into 5 groups, with 8 rats in each group: Group 1 control; Group 2 silver sulfadiazine; Group 3 mupirocin; Group 4 Acticoat group; and Group 5 octenidine dihydrochloride group. Following to the formation of the full-thickness burn areas in rats, the MDR A. baumannii standard strain was inoculated into the burned area. The rats in all the groups were sacrificed at the end of the 10th day and subjected to histopathological and microbiological evaluation. In the histopathological evaluation, the lowest inflammatory cell response and bacterial density in the eschar and muscle tissues were observed in the Acticoat group. While these results were found to be statistically significant compared to the silver sulfadiazine group, only the bacterial density in the muscle tissue was found as significant in comparison to the mupirocin and octenidine groups. In the microbiological evaluation, the lowest growth in the muscle tissue culture among all the groups was observed in the Acticoat group. The growth in the eschar tissue culture was significantly lower in the Acticoat and octenidine groups in comparison to the silver sulfadiazine group. At the end of the study, it has been observed that Acticoat was effective both in eschar and muscle, while octenidine was effective in eschar tissues in a rat burn model contaminated with MDR A. baumannii.

Fournier's Gangrene: Conventional Dressings versus Dressings with Dakin's Solution

Purpose. Fournier's gangrene is a fulminant and destructive inflammation of the scrotum, penis, and perineum. The objective of this study was to compare 2 different approaches to wound management after aggressive surgical debridement. Methods. Data from 14 patients with Fournier's gangrene were retrospectively collected (2005–2011). Once the patients were stabilized following surgery, they were treated with either daily antiseptic (povidone iodine) dressings (group I, n = 6) or dressings with dakin's solution (sodium hypochloride) (group II, n = 8). Results. The mean age of the patients was 68.2 ± 7.8 (55–75) years in group I and 66.9 ± 10.2 (51–79) years in group II. Length of hospital stay was 13 ± 3.5 (7–16) days in group I and 8.9 ± 3.0 (4–12) days in group II (P < 0.05). The number and rate of mortality was 1/6 (16.7%) in group I, and 1/8 (12.5%) in group II. Conclusions. The hospitalization time can be reduced with the use of dakin's solution for the dressings in the treatment of FG. Also, dressings with dakin's solution seems to have favorable effects on morbidity and mortality. Consequently dakin's solution may alter the treatment of this disastrous disease by reducing cost, morbidity and mortality.

Comparative diffusion assay to assess efficacy of topical antimicrobial agents against Pseudomonas aeruginosa in burns care

Background

Severely burned patients may develop life-threatening nosocomial infections due to Pseudomonas aeruginosa, which can exhibit a high-level of resistance to antimicrobial drugs and has a propensity to cause nosocomial outbreaks. Antiseptic and topical antimicrobial compounds constitute major resources for burns care but in vitro testing of their activity is not performed in practice.

Results

In our burn unit, a P. aeruginosa clone multiresistant to antibiotics colonized or infected 26 patients over a 2-year period. This resident clone was characterized by PCR based on ERIC sequences. We investigated the susceptibility of the resident clone to silver sulphadiazine and to the main topical antimicrobial agents currently used in the burn unit. We proposed an optimized diffusion assay used for comparative analysis of P. aeruginosa strains. The resident clone displayed lower susceptibility to silver sulphadiazine and cerium silver sulphadiazine than strains unrelated to the resident clone in the unit or unrelated to the burn unit.

Conclusions

The diffusion assay developed herein detects differences in behaviour against antimicrobials between tested strains and a reference population. The method could be proposed for use in semi-routine practice of medical microbiology.

The novel antibacterial drug XF-70 is a potent inhibitor of Staphylococcus aureus infection of the burn wound

The authors report the findings of in vivo studies of XF-70 (a novel, dicationic porphyrin) against Staphylococcus aureus in a murine model of a burn wound infection. Mice received a 15% total body scald burn wound, which were inoculated with S. aureus (1.8 x 10 CFU). After 24 hours, escharectomies were performed and groups (n = 8) received single or two doses (6 hours apart) of XF-70* (100 microg/wound) or silver sulfadiazine, Acticoat, or saline applied topically. Viable bacteria were quantified from homogenized burn tissue biopsies and the spleen by plating dilutions onto agar plates and CFU determination. A single dose of XF-70 reduced bacterial burden by 98.77% (untreated: 2.78 +/- 2.96 x 10 CFU/g vs XF-70 treated: 3.4 +/- 0.19 x 10 CFU/g, P < .01). Two XF-70 doses reduced the growth of S. aureus by 99.96% (1.2 +/- 0.6 x 10 CFU/g, P < .01). These results were similar to the results obtained from commonly used topical antibacterials silver sulfadiazine and Acticoat. The spleens of mice treated with saline had a robust growth of S. aureus (7.0 +/- 1.97 x 10 CFU/g) whereas those treated with one or two XF-70 doses grew only 3.5 +/- 0.002 x 10 CFU/g and 5.7 +/- 0.002 x 10 CFU/g, respectively, a significant (P < .001) reduction in S. aureus dissemination. Single and multiple doses of XF-70 were effective in controlling S. aureus growth in burn wounds and inhibited systemic dissemination of S. aureus. Early treatment of burn wounds with XF-70 may be effective in slowing bacterial dissemination to other tissues.

Review of burn injury research for the year 2009

Research in burn care for the calendar year 2009 was robust and diverse with >1400 research articles published on a wide range of topics. In this review, the authors highlight some innovative and potentially impactful research related to the overall care of burn- injured patients. The authors grouped articles according to the following categories: critical care, infection, inhalation injury, epidemiology, psychology, wound characterization and treatment, nutrition and metabolism, pain and itch management, burn reconstruction, and rehabilitation. They found that the holistic nature of burn care is reflected in the diverse research performed in 2009 throughout the world and that this research has provided important evidence that has improved or will improve burn care overall.

Efficacy of topically delivered moxifloxacin against wound infection by Pseudomonas aeruginosa and methicillin-resistant Staphylococcus aureus

Wound infection is a common risk for patients with chronic nonhealing wounds, causing high morbidity and mortality. Currently, systemic antibiotic treatment is the therapy of choice, despite often leading to several side effects and the risk of an insufficient tissue penetration due to impaired blood supply. If systemically delivered, moxifloxacin penetrates well into inflammatory blister fluid, muscle, and subcutaneous adipose tissues and might therefore be a possible option for the topical treatment of skin and infected skin wounds. In this study, topical application of moxifloxacin was investigated in comparison to mupirocin, linezolid, and gentamicin using a porcine wound infection and a rat burn infection model. Both animal models were performed either by an inoculation with methicillin-resistant Staphylococcus aureus (MRSA) or Pseudomonas aeruginosa. Wound fluid, tissue, and blood samples were taken, and bacterial counts as well as the moxifloxacin concentration were determined for a 14-day follow-up. A histological comparison of the rat burn wound tissues was performed. Both strains were susceptible to moxifloxacin and gentamicin, whereas mupirocin and linezolid were effective only against MRSA. All antibiotics showed efficient reduction of bacterial counts, and except with MRSA, infected burn wounds reached bacterial counts below 10(5) CFU/g tissue. Additionally, moxifloxacin was observed to promote wound healing as determined by histologic analysis, while no induction of bacterial resistance was observed during the treatment period. The use of topical antibiotics for the treatment of infected wounds confers many benefits. Moxifloxacin is therefore an ideal candidate, due to its broad antibacterial spectrum, its high efficiency, and its potential to promote wound healing.

Activity of topical antimicrobial agents against multidrug-resistant bacteria recovered from burn patients

BACKGROUND

Topical antimicrobials are employed for prophylaxis and treatment of burn wound infections despite no established susceptibility breakpoints, which are becoming vital in an era of multidrug-resistant (MDR) bacteria. We compared two methods of determining topical antimicrobial susceptibilities.

METHODS

Isolates of Pseudomonas aeruginosa, methicillin-resistant Staphylococcus aureus (MRSA), extended spectrum beta-lactamase (ESBL) producing Klebsiella pneumoniae, and Acinetobacter baumanii-calcoaceticus (ABC) from burn patients were tested using broth microdilution and agar well diffusion to determine minimum inhibitory concentrations (MICs) and zones of inhibition (ZI). Isolates had systemic antibiotic resistance and clonality determined. MDR included resistance to antibiotics in three or more classes.

RESULTS

We assessed 22 ESBL-producing K. pneumoniae, 20 ABC (75% MDR), 20 P. aeruginosa (45% MDR), and 20 MRSA isolates. The most active agents were mupirocin for MRSA and mafenide acetate for the gram-negatives with moderate MICs/ZI found with silver sulfadiazene, silver nitrate, and honey. MDR and non-MDR isolates had similar topical resistance. There was no clonality associated with resistance patterns.

CONCLUSION

Despite several methods to test bacteria for topical susceptibility, no defined breakpoints exist and standards need to be established. We recommend continuing to use silver products for prophylaxis against gram-negatives and mafenide acetate for treatment, and mupirocin for MRSA.