The maintenance of an aseptic environment for chronic wounds is one of the most challenging tasks in the wound-healing process. Furthermore, the emergence of antibiotic-resistant bacterial strains is on the rise, rendering conventional treatments less effective. A new antibacterial material consisting of a polyurethane Tecophilic(™) nanofibre textile (NT) that was prepared by electrospinning and doped by a tetraphenylporphyrin (TPP) photosensitizer activated by visible light was tested for use in wound beds and bandages. In vitro experiments were performed to assess the antibacterial activity of the textile against three bacterial strains. Furthermore, the new textile was tested in 162 patients with chronic leg ulcers. A complete inhibition of in vitro growth of the three tested bacterial strains was observed on the surface of NTs that had been illuminated with visible light and was clinically demonstrated in 89 patients with leg ulcers. The application of the textiles resulted in a 35% decrease in wound size, as assessed via computer-aided wound tracing. Wound-related pain, which was estimated using a visual analogue scale, was reduced by 71%. The results of this trial reveal that the photoinactivation of bacteria through the photosensitized generation of short-lived, highly reactive singlet oxygen O(2) ((1) Δ(g) ) results in relatively superficial antibacterial effects in comparison with standard antiseptic treatment options. Thus, such treatment does not interfere with the normal healing process. This method therefore represents a suitable alternative to the use of topical antibiotics and antiseptics and demonstrates potentially broad applications in medicine.
To predict the outcome of urine cultures, several screening methods have been developed. [1][2][3] In photometric screening, 2 diluted urine specimen is added to the broth in microplate well and incubated; if the specimen contains at least 10 5 bacteria/ mL, optical density (OD) in the well increases signiÞ cantly within Þ ve hours. The aim of this study was to verify this method using a kinetic microplate reader.Four hundred thirty midstream urine specimens were tested by the standard culture method. Specimens with counts ≥ 10 5 cfu/mL were considered positive. The specimens were also evaluated using a photometric screening. Urine specimens (100 µL) were inoculated in to 100 µL of brain heart infusion (Oxoid, Basingstoke, UK) enriched with 8% of concentrated tissue culture medium E-199 (Sevapharma Prague, Czech Rep) in microtitre wells. The plate was placed on a photometer (MRX HD; Dynex Laboratories, Chantilly, VA). The temperature of the microplate chamber was maintained at 36°C. The optical density (OD) of inoculated wells was measured every ten minutes at a wavelength of 420 nm. Wells with an OD increase of ≥7% in four hours were considered as positive. Curves of turbidity increase were also received and those that contained an exponential segment were considered positive. The quantitative culture test and photometric screening thus resulted in three logical values: signiÞ cant/ insigniÞ cant bacteriuria; presence/ absence of 7% increase in OD in four hours; and presence/ absence of an exponential segment in curve. Relation among those logical values was expressed as sensitivity and speciÞ city, positive and negative predictive values of the screening.
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