Comparative Antimicrobial Activity of Commercial Wound Care Solutions on Bacterial and Fungal Biofilms.

BACKGROUND: Biofilms represent a complex milieu of matrix-enclosed microorganisms, which can significantly contribute to the pathology of chronic wounds. In this study, we compare the activity of 3 commercial antimicrobial wound care solutions, Vashe (HOCl based), PhaseOne (HOCl based), and Sulfamylon (mafenide acetate), for their in vitro activity against bacterial and fungal biofilms. METHODS: Reference and clinical isolates of 6 Gram-negative bacterial species (36 total strains), 3 Gram-positive bacteria (21 strains), and 3 Candida species (9 strains) were used to create biofilms. Various working concentrations of the 3 antiseptic agents were incubated with the biofilms in microwell plates; they were monitored from 1 minute to 24 hours to compare bacterial and fungal viability through colony forming unit analysis. RESULTS: Vashe and PhaseOne displayed excellent bactericidal and fungicidal activity, whereas Sulfamylon demonstrated minimal activity against the biofilms tested. With the exception of Candida albicans, all biofilms were eliminated at either 1 or 10 minutes using Vashe and PhaseOne solutions. In most cases, mafenide was unable to eliminate both bacterial and fungal biofilms, even with 24 hours of treatment. CONCLUSIONS: Biofilms represent a major clinical challenge, with no clear consensus for treatment of chronic wounds or prosthetic devices. Our results suggest that hypochlorous acid-based wound solutions such as Vashe and PhaseOne are more efficacious than mafenide in eliminating bacterial and fungal biofilms. Further studies are necessary to investigate and compare the in vivo efficacy of these products in clinical care.

Incidence of Laryngotracheal Stenosis after Thermal Inhalation Airway Injury.

Inhalation injury is independently associated with burn mortality, yet little information is available on the incidence, risk factors, or functional outcomes of thermal injury to the airway. In patients with thermal inhalation injury, we sought to define the incidence of laryngotracheal stenosis (LTS), delineate risk factors associated with LTS development, and assess long-term tracheostomy dependence as a proxy for laryngeal function. Retrospective cohort study of adult patients treated for thermal inhalation injury at a single institution burn critical care unit from 2012 to 2017. Eligible patients' records were assessed for LTS (laryngeal, subglottic, or tracheal stenosis). Patient characteristics, burn injury characteristics, and treatment-specific covariates were assessed. Descriptive statistics, Mann-Whitney U-tests, odds ratio, and chi-square tests compared LTS versus non-LTS groups. Of 129 patients with thermal inhalation injury during the study period, 8 (6.2%) developed LTS. When compared with the non-LTS group, patients with LTS had greater mean TBSA (mean 30.3, Interquartile Range 7-57.5 vs 10.5, Interquartile Range 0-15.12, P = .01), higher grade of inhalation injury (mean 2.63 vs 1.80, P = .05), longer duration of intubation (12.63 vs 5.44; P < .001), and greater inflammatory response (mean white blood cell count on presentation 25.8 vs 14.9, P = .02, mean hyperglycemia on presentation 176.4 vs 136.9, P = .01). LTS patients had a significantly higher rate of tracheostomy dependence at last follow-up (50 vs 1.7%, P < .001). Six percent of patients with thermal inhalation injury develop LTS. LTS was associated with more severe thermal airway injury, longer duration of intubation, and more severe initial host inflammation. Patients with inhalation injury and LTS are at high risk for tracheostomy dependence. In burn patients with thermal inhalation injury, laryngeal evaluation and directed therapy should be incorporated early into multispecialty pathways of care.

The Effective Duration of Antimicrobial Activity of Mafenide Acetate After Reconstitution.

Mafenide acetate is an effective but costly antimicrobial solution used for burn wounds. The package insert instructs the user to discard unused solution within 48 hours of opening. The purpose of this study is to evaluate the antimicrobial activity of mafenide acetate beyond 48 hours after reconstitution, to possibly reduce cost by eliminating product waste. Staphylococcus aureus and Pseudomonas aeruginosa isolates were used to seed Mueller-Hinton agar plates. Filter paper disks were then saturated with 5% mafenide acetate at 0, 2, 7, 14, 30, and 60 days after reconstitution. Disks were then placed on the seeded agar plates and incubated. After incubation, the zone of inhibition around each plate was measured. A zone of inhibition of 2 mm or greater was indicative of susceptibility. Mafenide acetate remained efficacious, with a zone of inhibition of >2 mm to both organisms at 0, 2, 7, 14, 30, and 60 days after mafenide acetate reconstitution. This in vitro study demonstrates that the antimicrobial activity of mafenide acetate remains present for at least 60 days after reconstitution. Unused mafenide may not need to be discarded at 48 hours after opening. Reducing wasted product has the potential to translate into cost savings.

Utility and outcomes of hydroxocobalamin use in smoke inhalation patients.

INTRODUCTION: Hydroxocobalamin has been available for use for suspected cyanide toxicity in smoke inhalation patients in the United States since 2006. Our study compares outcomes of patients who received hydroxocobalamin to historical controls who did not. METHODS: In this retrospective review, patients administered hydroxocobalamin (2008-2014) were compared to historical controls (2002-2008). Patients <18 years, patients who received an alternate antidote, and patients without suspicion of smoke inhalation injury were excluded. Mortality was the primary outcome. Secondary outcomes evaluated were 7-day change in creatinine, culture-proven pneumonia, days on mechanical ventilation, ventilator- free days (VFD), ICU length of stay (ICU LOS), and hospital length of stay (HLOS). RESULTS: A total of 138 patients in the hydroxocobalamin group and 135 in the control group were identified. Mortality rate was similar between both groups (29% vs. 28%, p=0.90). Hydroxocobalamin was associated with lower pneumonia rate (23% vs. 49%, p<0.01), less ventilator days (4 days vs. 7 days, p<0.01), and increased VFD (20 days vs. 11 days, p=0.01) compared to controls. Shorter ICU LOS (6 days vs. 10 days, p=0.03) and a trend toward lower HLOS (7 day vs. 11 days, p=0.06) were also found in patients who received hydroxocobalamin. CONCLUSIONS: Routine administration was associated with lower rate of pneumonia, faster liberation from the ventilator, and reductions in intensive care unit stay. Burn centers should consider its empiric use in suspected smoke inhalation patients.

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.

Fluid resuscitation mediates the association between inhalational burn injury and acute kidney injury in the major burn population.

BACKGROUND: It is known that acute respiratory distress syndrome and acute lung injury are independent risk factors for developing acute kidney injury (AKI) through complex pathophysiologic mechanisms. Our specific aim is to evaluate the risk factors for AKI postburn injury and whether inhalation thermal injury is an independent risk factor for developing AKI in the major burn population. METHODS: This is an institutional review board-approved, retrospective cohort study of patients admitted to a tertiary burn intensive care unit between 2011 and 2013. We included adults (age 18 years or older) with major burn injury greater than or equal to 20% total burn surface area (TBSA) and patients with confirmed inhalation injury (±major burn). Acute kidney injury was defined using the acute kidney injury network serum creatinine criteria up to 5 days after admission. Patient demographics and clinical data were compared across cohorts using the Wilcoxon rank sum test or Pearson χ2 test, as appropriate. Multiple logistic regression was used to assess the effect of inhalation injury and major burn on the incidence of AKI, adjusting for clinical and demographic confounders. RESULTS: Two hundred fifty-four patient records (90 with inhalation injury and 164 with major burn only) were evaluated. The mean age on admission was 47±19 years and 72% of the cohort were men. There were more men in the major burn group (78% vs 62%; P=.007). No other significant differences were observed in the baseline demographics. The overall incidence of AKI was 28% (95% confidence interval, 22, 33). The unadjusted odds of AKI were nearly double (odds ratio, 1.99; 95% confidence interval, 1.13, 3.49) among those with inhalation injury relative to those with major burn only. However, there was no evidence of an independent inhalational injury effect after adjusting for potential confounders. In particular, TBSA (P=.051), daily 24-hour fluid balance (P<.001), and most recent 24-hour albumin transfusion status (P=.002) were all significantly associated with AKI in the adjusted analysis. Age and packed red blood cell transfusion status were not significant. CONCLUSION: Inhalation thermal injury is not an independent risk factor for AKI after adjusting for TBSA and surrogates for fluid resuscitation. In patients with major burns, intensity of fluid resuscitation may mediate the development of AKI.

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.