Assessment of Silver Levels in a Closed-Incision Negative Pressure Therapy Dressing: In Vitro and In Vivo Study.

Objective: In recent years, reticulated open-cell foam-based closed-incision negative pressure therapy (ROCF-ciNPT) has shown effectiveness in management of various postoperative incisions. These dressings consist of a skin interface layer that absorbs fluid from the skin surface and reduces the potential for microbial colonization within the dressing by means of ionic silver. This study examines the ability of silver to reduce the bioburden within the dressing as well as the localized effect due to potential silver mobility. Approach: Ability of silver to reduce bioburden within the ROCF-ciNPT dressing was assessed using Staphylococcus aureus, Pseudomonas aeruginosa, and Candida spp. Furthermore, silver mobility was assessed using an in vitro skin model to study the zone of inhibition along with released silver quantification. Using a porcine model, diffusion of silver into blood and tissue was studied using emission spectrometry and histology. Results: Microbial growth in the ROCF-ciNPT dressing was significantly reduced (∼2.7-4.9 log reduction) compared to a silver-free negative control. No zone of inhibition was observed for microbial colonies for up to 7 days with minimal localized silver release (<5.5 ppm release). In vivo studies demonstrated no measurable concentration (<0.2 µg/g) of silver in the blood, urine, feces, kidney, and liver tissue biopsy. Innovation: This study provides an important insight into silver concentration and mobility within the ROCF-ciNPT dressing, given emerging concerns associated with potential silver cytotoxicity. Conclusion: These results indicate the concentration of silver (0.019% silver by weight) in the ROCF-ciNPT dressings has been adequate to reduce bioburden within the skin interface layer, while severely limiting the amount of silver leaching out.

An Intact Cell Bioluminescence-Based Assay for the Simple and Rapid Diagnosis of Urinary Tract Infection.

Urinary tract infection (UTI) is one of the most common infections, accounting for a substantial portion of outpatient hospital and clinic visits. Standard diagnosis of UTI by culture and sensitivity can take at least 48 h, and improper diagnosis can lead to an increase in antibiotic resistance following therapy. To address these shortcomings, rapid bioluminescence assays were developed and evaluated for the detection of UTI using intact, viable cells of Photobacterium mandapamensis USTCMS 1132 or previously lyophilized cells of Photobacterium leiognathi ATCC 33981™. Two platform technologies-tube bioluminescence extinction technology urine (TuBETUr) and cellphone-based UTI bioluminescence extinction technology (CUBET)-were developed and standardized using artificial urine to detect four commonly isolated UTI pathogens-namely, Escherichia coli, Proteus mirabilis, Staphylococcus aureus, and Candida albicans. Besides detection, these assays could also provide information regarding pathogen concentration/level, helping guide treatment decisions. These technologies were able to detect microbes associated with UTI at less than 105 CFU/mL, which is usually the lower cut-off limit for a positive UTI diagnosis. Among the 29 positive UTI samples yielding 105-106 CFU/mL pathogen concentrations, a total of 29 urine specimens were correctly detected by TuBETUr as UTI-positive based on an 1119 s detection window. Similarly, the rapid CUBET method was able to discriminate UTIs from normal samples with high confidence (p ≤ 0.0001), using single-pot conditions and cell phone-based monitoring. These technologies could potentially address the need for point-of-care UTI detection while reducing the possibility of antibiotic resistance associated with misdiagnosed cases of urinary tract infections, especially in low-resource environments.

Candidemia and candiduria in critically ill patients admitted to intensive care units in France: incidence, molecular diversity, management and outcome.

OBJECTIVE: To determine the concomitant incidence, molecular diversity, management and outcome of nosocomial candidemia and candiduria in intensive care unit (ICU) patients in France. DESIGN: A 1-year prospective observational study in 24 adult ICUs. PATIENTS: Two hundred and sixty-two patients with nosocomial candidemia and/or candiduria. MEASUREMENTS AND RESULTS: Blood and urine samples were collected when signs of sepsis were present. Antifungal susceptibility of Candida strains was determined; in addition, all blood and 72% of urine C. albicans isolates were analyzed by using multi-locus sequence type (MLST). The mean incidences of candidemia and candiduria were 6.7 and 27.4/1000 admissions, respectively. Eight percent of candiduric patients developed candidemia with the same species. The mean interval between ICU admission and candidemia was 19.0 +/- 2.9 days, and 17.2 +/- 1.1 days for candiduria. C. albicans and C. glabrata were isolated in 54.2% and 17% of blood and 66.5% and 21.6% of urine Candida-positive cultures, respectively. Fluconazole was the most frequently prescribed agent. In all candidemic patients, the prescribed curative antifungal agent was active in vitro against the responsible identified strain. Crude ICU mortality was 61.8% for candidemic and 31.3% for candiduric patients. Seventy-five percent of the patients were infected with a unique C. albicans strain; cross-transmission between seven patients was suggested in one hospital. CONCLUSIONS: Candidemia is late-onset ICU-acquired infection associated with high mortality. No difference in susceptibility and genetic background were found between blood and urine strains of Candida species.

[Evaluation of chromogenic medium CPS ID2 (bioMérieux) in urine cultures]. / Evaluación del medio cromogénico CPS ID2 (bioMérieux) en urinocultivos.

BACKGROUND: The aim of the study was to evaluate the chromogenic agar plate CPS ID2 (bioMérieux) and determine its cost-benefit ratio. METHODS: A total of 2,193 urinary sediments were processed. The urine culture was carried out in CPS ID2 agar and in cystine-lactose electrolyte deficient (CLED) agar, when needed. Identification of the microorganisms was performed following standard microbiologic procedures through biochemical tests prepared in our laboratory. The identification, from CPS ID2 agar, by direct detection in medium of four metabolic activities: beta-glucuronidase, beta-glucosidase, deaminase, and indol production, was performed following to manufacturer's instructions. RESULTS: A total of 289 urine cultures were positive, 18 were negative and 34 were contaminated samples. The identification, directly performed from the colonies detected in CPS ID2 agar, was correct in 96% of 166 Escherichia coli, in 92% of 24 Proteus mirabilis and in 97% of 38 enterococci. CPS ID2 agar exhibited 94% and 100% sensitivity and specificity, respectively in E. coli identification, 92% and 100% in P. mirabilis and 97% and 99% in Enterococcus. The use of this new media, CPS ID2, in our laboratory, implies a budgetary increment. However, if commercial galleries are used for routine identification, the cost will be reduced using this new media. CONCLUSIONS: The CPS ID2 agar allows the isolation and direct identification of the most frequent urinary tract pathogens: E. coli, P. mirabilis and Enterococcus in primary isolation medium. Using this medium, bacteriologists will be able to save time and reagents when identifying the most common uropathogens. Furthermore, the use of this medium would reduce costs in some laboratories.

Oral fluconazole versus amphotericin B bladder irrigation for treatment of candidal funguria.

A randomized trial was conducted to compare amphotericin B bladder irrigation (AmBBI) with oral fluconazole in terms of efficacy and safety in the treatment of candidal funguria. Fifty-three patients with two consecutive positive funal cultures of urine were randomized to undergo AmBBI (50 mg/L over 24 hours or 50 mg/L for 7 days) or to receive fluconazole (200 mg/d for 7 days). Urinary catheters were changed upon entry into the study and following therapy. Blood and urine specimens were obtained throughout the study. Candida albicans was the species isolated most frequently from urine cultures. Eradication rates for funguria at 24 hours and 5-9 days after therapy were 82.4% and 75%, respectively, with the 7-day AmBBI regimen; and 83.3% and 76.9%, respectively, with fluconazole. There were no differences in the posttherapy eradication rates between the regimens at 24 hours (P = .597) and at 5-9 days (P = .66). Candida glabrata was the predominant organism recovered from patients in the fluconazole group 5-9 days after the completion of therapy. Adverse events were limited to bladder fullness in a patient who underwent AmBBI and hypoglycemia in a patient who received concomitant therapy with fluconazole and glyburide. AmBBI (once or for 7 days) and fluconazole appear to be equally efficacious in the treatment of candidal funguria.