The prevalence of phenotypic silver resistance in clinical isolates.

UNLABELLED: Research has shown silver to be an effective antimicrobial agent against bacteria, virus, yeast, and fungi. Due to the increased use of silver-based wound products during the past decade, concerns of widespread silver resistance have been raised.1 The purpose of this study was to assess the prevalence of phenotypic silver resistance in clinical isolates. METHODS: A total of 130 different microorganism strains were collected from patients admitted to a tertiary care hospital. To determine phenotypic silver resistance, a corrected zone of inhibition (CZOI) test was used. The isolate (0.1 mL) was streaked on nutrient agar in 3 directions to form a confluent lawn. A silver dressing and a control gauze dressing were placed on the lawn and incubated for 24 hours. The CZOI was determined by averaging the zone of clearance in both directions across the dressing and then subtracting the dressing size. Corrected zone of inhibition tests were conducted in duplicate. To confirm the silver dressing killed the microorganism and did not simply hinder bacterial growth, a culture was taken from underneath each silver dressing and plated separately. RESULTS: All of the isolates showed no growth when tested against the silver-based dressing. The CZOI values ranged between 0.0 mm and 7.25 mm. No growth was observed in the secondary culture from underneath the dressing, indicating the silver dressing was bactericidal for all 130 isolates tested and not simply bacteriostatic. The control gauze dressing did not show any antimicrobial properties. CONCLUSION: The threat of widespread silver resistance in clinical isolates remains low. However, continued monitoring for silver resistance should be maintained.

Alteration in prehospital drug concentration after thermal exposure.

OBJECTIVE: The aim of the study was to determine the remaining concentration of 23 commonly carried emergency medical services medications used in the United States after they have experienced thermal extremes that have been documented in the prehospital environment for a period of 1 month. METHODS: Pharmaceuticals were thermally cycled (-6 degrees C and 54 degrees C) every 12 hours and then assayed by high-performance liquid chromatography. RESULTS: Eight (35%) of 23 prehospital pharmaceuticals revealed ending concentrations of less than 90% with strong correlation to thermal exposure time. These included lidocaine, diltiazem, dopamine, nitroglycerin, ipratropium, succinylcholine, haloperidol, and naloxone. CONCLUSION: A decrease in concentration was found to be statistically significant in 8 (35%) of 23 commonly carried emergency medical services pharmaceuticals. These results provide new information and perspective regarding stability of emergency drugs in the prehospital environment by evaluating a broad range of pharmaceuticals as well as by using thermal exposure points that have been documented in the United States.

A clinical trial to investigate the effect of silver nylon dressings on mediastinitis rates in postoperative cardiac sternotomy incisions.

Mediastinitis is a rare but serious postoperative complication of cardiac surgery that increases mortality rates, hospital length of stay, and medical costs. A clinical trial was conducted to investigate whether the type of postoperative surgical dressing (silver nylon or standard gauze) affects the rate of mediastinal infections. The sample consisted of 1,600 surgical cardiac patients. Infection rates in the standard gauze group (control, n = 1,235) were collected retrospectively from 24 months of infection control records. In the prospective treatment arm of the study, the wounds of all consecutive surgical patients (n = 365) were covered with a silver nylon dressing and patients were assessed during the 3-week postoperative visit. Thirteen (13) patients in the control group (1%) and none of the patients in the treatment group developed mediastinitis (chi2 [1, N = 1,600] = 3.88, P <0.05). Study findings support the need for a large, prospective, controlled clinical study to confirm the effects of these dressings on mediastinitis, resultant morbidity, and costs of care.

Silver dressings improve diabetic wound healing without reducing bioburden.

UNLABELLED: Introduction. Silver dressings are widely used in the treatment of chronic wounds to reduce bacterial bioburden. However, little is known about the mechanism of silver ions on the healing process. In this study, a mouse model of wound healing was used to examine the effect of silver dressings in normal and diabetic wounds. METHODS: Two 5-mm full-thickness wounds were created on the dorsal skin of diabetic BKS.Cg- m+/+Leprdb/J mice (experimental group) and wild type C57BL/6 mice (control group), and treated with either a silver or gauze dressing. Measurement of wound areas by digital planimetry demonstrated faster healing in the silver-treated wounds of both diabetic and control mice. RESULTS: Quantitative bacterial cultures showed a reduction of bioburden in silver-treated wounds in wild type mice. Unexpectedly, there was no decrease in bioburden in the silver-treated diabetic wounds compared to the control diabetic wounds, despite improved healing in the silver-treated diabetic wounds. Staphylococcus xylosus, a known biofilm producer, was the only bacteria identified in all the wounds. In vitro studies showed S. xylosus produced biofilms faster in higher glucose environments; this may explain the increased bioburden in the wounds in diabetic mice compared to wild type mice. CONCLUSION: The results demonstrate improved healing and reduced bioburden in normal wounds with silver dressings. In contrast, silver dressings improved healing in diabetic wounds despite no effect on bioburden, suggesting silver may have beneficial effects in addition to its antimicrobial properties.

Wound closure after split-thickness skin grafting is accelerated with the use of continuous direct anodal microcurrent applied to silver nylon wound contact dressings.

Wound healing after graft closure of excised burn wounds is a critical factor in the recovery process after thermal injury. Processes that speed time to stable wound closure should lead to improved outcomes, shorter lengths of hospital stays, and decreased complications. A randomized clinical trial to test the ability of continuous direct anodal microcurrent application to silver nylon wound contact dressings was designed. Time for wound closure after split-thickness skin grafting was observed. Thirty patients with full-thickness thermal burns were randomized into two groups. The control group received postoperative dressing care using moistened silver nylon fabric covered with gauze after tangential burn wound excision and split-thickness skin grafting. The study group received an identical protocol with the addition of continuous direct anodal microcurrent application. Time to 95% wound closure was measured using digital photography. The digital photographs were evaluated by a burn surgeon blinded to the patient's randomization. An independent t-test was used to analyze the data. The study group experienced a 36% reduction in time to wound closure (mean of 4.6 days) as compared to the control group (mean of 7.2 days). This was statistically significant at a P value of <.05. The use of continuous direct anodal microcurrent decreased time to wound closure after split-thickness skin grafting.

Practice patterns and outcomes of retrievable vena cava filters in trauma patients: an AAST multicenter study.

BACKGROUND: The purpose of this study is to describe practice patterns and outcomes of posttraumatic retrievable inferior vena caval filters (R-IVCF). METHODS: A retrospective review of R-IVCFs placed during 2004 at 21 participating centers with follow up to July 1, 2005 was performed. Primary outcomes included major complications (migration, pulmonary embolism [PE], and symptomatic caval occlusion) and reasons for failure to retrieve. RESULTS: Of 446 patients (69% male, 92% blunt trauma) receiving R-IVCFs, 76% for prophylactic indications and 79% were placed by interventional radiology. Excluding 33 deaths, 152 were Gunter-Tulip (G-T), 224 Recovery (R), and 37 Optease (Opt). Placement occurred 6 +/- 8 days after admission and retrieval at 50 +/- 61 days. Follow up after discharge (5.7 +/- 4.3 months) was reported in 51%. Only 22% of R-IVCFs were retrieved. Of 115 patients in whom retrieval was attempted, retrieval failed as a result of technical issues in 15 patients (10% of G-T, 14% of R, 27% of Opt) and because of significant residual thrombus within the filter in 10 patients (6% of G-T, 4% of R, 46% Opt). The primary reason R-IVCFs were not removed was because of loss to follow up (31%), which was sixfold higher (6% to 44%, p = 0.001) when the service placing the R-IVCF was not directly responsible for follow up. Complications did not correlate with mechanism, injury severity, service placing the R-IVCF, trauma volume, use of anticoagulation, age, or sex. Three cases of migration were recorded (all among R, 1.3%), two breakthrough PE (G-T 0.6% and R 0.4%) and six symptomatic caval occlusions (G-T 0, R 1%, Opt 11%) (p < 0.05 Opt versus both G-T and R). CONCLUSION: Most R-IVCFs are not retrieved. The service placing the R-IVCF should be responsible for follow up. The Optease was associated with the greatest incidence of residual thrombus and symptomatic caval occlusion. The practice patterns of R-IVCF placement and retrieval should be re-examined.