Antibiotic susceptibility and resistance of Staphylococcus aureus isolated from fresh porcine skin xenografts: risk to recipients with thermal injury.

The previous use of fresh porcine xenografts at the Prague Burn Centre had raised concerns over the transmission of zoonotic pathogens. This study examines the risk of zoonotic Staphylococcus aureus colonisation of burn patients from fresh porcine skin xenografts. Samples were collected from the nares, skin and perineum of commercial pigs (n=101) and were screened for methicillin sensitive S. aureus (MSSA) and resistant S. aureus (MRSA). The efficacy of the antibiotic wash used in decontamination of the pigskin was tested against planktonic- and biofilm-grown isolates. The spa type of each isolate was also confirmed. All pig swabs were negative for MRSA but 86% positive for MSSA. All planktonic-grown isolates of MSSA were sensitive to chloramphenicol and nitrofurantoin and 44% of isolates were resistant to streptomycin. Isolates grown as biofilm exhibited higher rates of antimicrobial resistance. Sequence analysis revealed three distinct spa types of the MRSA ST398 clonal type. This finding demonstrates the existence of a MSSA reservoir containing spa types resembling those of well-known MRSA strains. These MSSA exhibit resistance to antibiotics used for decontamination of the pigskin prior to xenograft. Amended use of procurement could allow the use of fresh pigskin xenografts to be reinstated.

[Validation of an automatic test system for sterile testing of amniotic membranes]. / Validierung eines automatischen Testsystems für die Steriltestung von Amnionmembran.

PURPOSE: The use of cryopreserved amniotic membranes for the treatment of diseases and injuries of the surface of the eye is an established procedure in ophthalmological surgery. Before clinical use of cryopreserved amniotic membranes (AM) a careful testing for microbial contamination is essential to ensure a safe application. In this study the use of the BacT/Alert® test system was evaluated for screening of microbial growth in AMs. MATERIALS AND METHODS: Minced fresh and cryopreserved AMs (approximately 5 × 5 cm in size) were injected with 10 ml of balanced salt solution in separate culture media test bottles and 10 ml of cryopreservation medium bacterial and fungal test strains according to European Union (EU) regulations were applied to test the performance of the system. Approximately 10-100 colony forming units were applied on the samples prior to injection in the corresponding test bottles. Bottles were incubated at 37 °C for 7 days. Positive controls contained only balanced salt solution and the test strains while negative controls contained the test material without microbial test strains. RESULTS: Growth of the test strains was detected in all inoculated samples from non-processed and cryopreserved AM within the 7-day incubation period. In samples of the cryopreservation medium only growth of the fungus Candida albicans could be detected. CONCLUSIONS: The automated BacT/Alert test system is suitable for testing of microbial safety of amniotic membranes but not for testing the cryopreservation medium in clinical practice according to EU regulations.

Mechanical, physical, antioxidant, and antimicrobial properties of gelatin films incorporated with thymol for potential use as nano wound dressing.

UNLABELLED: The aim of this study was to determine the properties of gelatin films incorporated with thymol. Gelatin films were prepared from gelatin solutions (10% w/v) containing thymol (1, 2, 4, and 8% w/w), glycerol (25% w/w) as plasticizer, and glutaraldehyde (2% w/w) as cross-linker. Cross-likened films showed higher tensile strength, higher elongation at break, lower Young's modulus, lower water solubility, lower swelling, lower water uptake, and lower water vapor permeability. Incorporation of thymol caused a significant decrease in tensile strength, increase in elongation at break, decrease in Young's modulus, increase in water solubility, decrease in swelling and water uptake, and increase in water vapor permeability slightly. The films incorporated with thymol exhibited excellent antioxidant and antibacterial properties. The antibacterial activity of the films containing thymol was greatest against Staphylucoccus aureus followed by Bacillus subtilis followed by Escherichia coli and then by Pseudomonas aeruginosa. Thus, gelatin films-containing thymol can be used as safe and effective source of natural antioxidant and antimicrobial agents with the purpose of evaluating their potential use as modern nano wound dressing. PRACTICAL APPLICATION: This study clearly demonstrates the potential of gelatin films incorporated with thymol as natural antioxidant and antimicrobial nano film. Such antimicrobial films exhibited excellent mechanical, physical, and water activities and could be used as antibacterial nano wound dressing against wounds burn pathogens.

Polymeric multilayers that localize the release of chlorhexidine from biologic wound dressings.

Biologic wound dressings contain animal-derived components and are susceptible to high infection rates. To address this issue, we report an approach that permits incorporation of non-toxic levels of the small molecule antiseptic 'chlorhexidine' into biologic dressings. The approach relies on the fabrication of polyelectrolyte multilayer (PEMs) films containing poly(allylaminehydrochloride) (PAH), poly(acrylicacid) (PAA), and chlorhexidine acetate (CX) on elastomeric poly(dimethylsiloxane) (PDMS) sheets. The PEMs (20-100 nm thick) are subsequently stamped onto the wound-contact surface of a synthetic biologic dressing, Biobrane, which contains collagen peptides. Chlorhexidine loading in the PEMs was tailored by tuning the number of (CX/PAA) bilayers deposited, providing burst release of up to 0.98 ± 0.06 µg/cm(2) of CX over 24 h, followed by zero-order release of 0.35 ± 0.04 µg/cm(2)/day for another week. Although the CX concentrations released were below the reported in vitro cytotoxicity limit (5 µg/mL over 24 h) for human dermal fibroblasts, they killed 4 log(10) counts of pathogenic bacteria Staphylococcus aureus in solution. The CX/PEMs could be stamped onto Biobrane with high efficiency to provide CX release kinetics and in vitro antibacterial activity similar to that on PDMS stamps. In a full-thickness 'splinted' dermal wound-model in normal wild-type mice, the CX-functionalized Biobrane showed no decrease in either its adherence to the wound-bed or wound closure rate over 14 days. The murine wounds topically inoculated with ∼10(5) CFU/cm(2) of S. aureus and treated with CX-functionalized Biobrane demonstrated a 3 log(10) decrease in the wound's bacterial burden within 3 days, compared to persistent bacterial colonization found in wounds treated with unmodified Biobrane (n = 10 mice, p < 0.005). Overall, this study presents a promising approach to prevent bacterial colonization in wounds under biologic dressings.

Apósito biológico esterilizado con gas óxido de etileno / A biological dressing sterilized using ethylene oxide gas

Objetivo: se presentó el resultado de una investigación preclínica dirigida a comprobar el poder esterilizante del gas óxido de etileno sobre la piel porcina empleada como apósito biológico. Métodos: se contaminaron 2 grupos de 60 muestras cada uno, de piel porcina liofilizada con una cepa de estafilococo coagulasa positivo y Pseudomona aeruginosa, respectivamente. El 25 por ciento de las muestras de cada grupo se envió al laboratorio de microbiología para comprobar la efectividad del método de contaminación. El 75 por ciento restante se trató durante diferentes períodos en una cámara de gas óxido de etileno y, posteriormente, se enviaron al laboratorio de microbiología para comprobar el grado de esterilidad. Resultados: se demostró la alta efectividad del gas óxido de etileno para esterilizar la piel porcina que es empleada como apósito biológico. Conclusiones: este método es seguro, por lo que es apropiado para el empleo en la clínica médica

Objective: to present the result from a preclinical research aimed to verify the sterilizing power of ethylene oxide gas on the porcine skin used as a biological dressing. Methods: two groups of 60 samples each of lyophilized porcine skin were contaminated with a strain of positive-coagulase staphylococcus and Pseudomona aeruginosa, respectively. The 25 percent of samples of each group was sent to microbiology laboratory to verify the effectiveness of contamination method. The remainder 75 percent was treated in different periods in a chamber of ethylene oxide gas and later, was sent to the above laboratory to verify the sterility degree. Results: it was demonstrated the effectiveness of the ethylene oxide gas to sterilize the porcine skin, which is used as a biological dressing. Conclusions: this method is safe, therefore it is appropriate to use in the medical clinic

Apósito biológico esterilizado con gas óxido de etileno / A biological dressing sterilized using ethylene oxide gas

Objetivo: se presentó el resultado de una investigación preclínica dirigida a comprobar el poder esterilizante del gas óxido de etileno sobre la piel porcina empleada como apósito biológico. Métodos: se contaminaron 2 grupos de 60 muestras cada uno, de piel porcina liofilizada con una cepa de estafilococo coagulasa positivo y Pseudomona aeruginosa, respectivamente. El 25 por ciento de las muestras de cada grupo se envió al laboratorio de microbiología para comprobar la efectividad del método de contaminación. El 75 por ciento restante se trató durante diferentes períodos en una cámara de gas óxido de etileno y, posteriormente, se enviaron al laboratorio de microbiología para comprobar el grado de esterilidad. Resultados: se demostró la alta efectividad del gas óxido de etileno para esterilizar la piel porcina que es empleada como apósito biológico. Conclusiones: este método es seguro, por lo que es apropiado para el empleo en la clínica médica(AU)

Objective: to present the result from a preclinical research aimed to verify the sterilizing power of ethylene oxide gas on the porcine skin used as a biological dressing. Methods: two groups of 60 samples each of lyophilized porcine skin were contaminated with a strain of positive-coagulase staphylococcus and Pseudomona aeruginosa, respectively. The 25 percent of samples of each group was sent to microbiology laboratory to verify the effectiveness of contamination method. The remainder 75 percent was treated in different periods in a chamber of ethylene oxide gas and later, was sent to the above laboratory to verify the sterility degree. Results: it was demonstrated the effectiveness of the ethylene oxide gas to sterilize the porcine skin, which is used as a biological dressing. Conclusions: this method is safe, therefore it is appropriate to use in the medical clinic(AU)

Microbiological safety and clinical efficacy of radiation sterilized amniotic membranes for treatment of second-degree burns.

Amniotic membranes collected from the placentae of screened donors were processed and sterilized by gamma irradiation at 25 kGy. The sterility assurance level (SAL) of gamma irradiated amniotic membranes and clinical efficacy in second-degree burn wound healing were evaluated. Processed air-dried amniotic tissue from 159 batches of processing was checked for the bioburden level before sterilization. About 39% of the tissues had bioburden in the range of 10(1)-10(2)/100 cm(2) and 54.8% in the range of 10(2)-10(3)/100 cm(2). Based on the bioburden of the processed tissue prior to sterilization and the D(10) value of 2.3 kGy for the radiation resistant reference strain Bacillus pumilus, the sterility assurance level of the amniotic membranes irradiated at 25 kGy is found to be 10(-7) to 10(-11). The burn wound healing rate was compared between the radiation sterilized amniotic membranes and glycerol preserved amniotic membranes. Fifty patients with partial-thickness burns (up to 70% TBSA) were selected for the study. The scalds constituted 82% (41 patients) whereas flame burns accounted for 18% (9 patients). Various aspects like ease of application, patient comfort, development of fluid under the membrane, bacterial culture of drained fluid, rate of epithelialization, development of hypertrophic scars, keloids, unstable scars and restriction of joint movements were recorded with the application of gamma irradiated and glycerol preserved membranes. Radiation sterilized amniotic membranes had advantage over the glycerolized membranes with respect to the ease of application. Five patients with glycerol preserved membranes and four with gamma irradiated membranes developed fluid. The bacteriology of fluid showed Pseudomonas aeruginosa in four cases, Staphylococcus aureus in two cases, Escherichia coli in two cases and Acinetobacter in one case. The application of radiation sterilized amniotic membranes on the burn wound favoured epithelialization. In all the patients, membranes dessicated and separated in 10-14 days time leaving behind an epithelialized surface.

[Biophysical properties of membrane dressing made of bacterial cellulose]. / O wlasciwosciach biofizycznych opatrunków membranowych z celulozy bakteryjnej.

In the paper, review of papers devoted to biophysical properties of membrane dressing made of bacterial cellulose was done. These properties were determined on the basis of studies on osmotic and diffusive transport through pure (non modified) bacterial cellulose membrane form called Bio-Fill. The measures of these properties are values of membrane transport parameters resulted from Kedem-Katchalsky's theory and interferograms of near-membrane regions made laser interferometric method.

[Medical properties of the membrane dressing made of bacterial cellulose]. / O wlasciwosciach medycznych opatrunków membranowych z celulozy bakteryjnej.

Review of papers devoted to medical properties of membrane dressing made of bacterial cellulose was done. These properties were determined on the basis of studies on application of this membrane to venous leg ulcer healing. Moreover, quantitative method of valuation of wound healing process efficiency which lies in calculating efficiency coefficient was described. Value of this coefficient is directly proportional to ulcer healing speed and indirectly proportional to product of initial surface and healing time.

Microbial keratitis after amniotic membrane transplantation.

PURPOSE: To determine the incidence of early-onset (<30 days) and late-onset (>30 days) microbial keratitis after treatment of persistent corneal epithelial defects with amniotic membrane transplantation (AMT) utilizing tissue acquired from a commercial laboratory or prepared by the institutional eye bank. METHODS: A retrospective, non-randomized, sequential, comparative study was performed for every patient with a persistent corneal epithelial defect who underwent primary AMT at KKESH between January 1, 2003 and June 30, 2004. RESULTS: A total of 142 AMT procedures were performed for persistent corneal epithelial defects during the study period. There were 72 cases using commercially prepared tissue and 70 cases using locally prepared tissue. The mean patient age was 50.3+/-25.6 years (range, 1-104 years). The mean follow up was 6.3+/-5.0 months (range, 1-21 months). There were no cases of early-onset microbial keratitis in cases in which either commercially acquired tissue or locally prepared tissue was used. CONCLUSION: Amniotic tissue prepared in a commercial laboratory or by properly qualified eye bank personnel may be used for AMT in eyes with persistent corneal epithelial defects with minimal risk of microbial keratitis in the first postoperative month.