Gentamicin-Impregnated Collagen Sponge: Effectiveness in Preventing Sternal Wound Infection in High-Risk Cardiac Surgery

Sternal wound infections represent one of the most frequent complications after cardiac surgery and are associated with high postoperative mortality. Several preventive methods have been introduced, and recently, gentamicin-impregnated collagen sponges (GICSs) have shown a promising effect in reducing the incidence of this type of complications. Gentamicin is an aminoglycoside antibiotic that has been widely used to treat infections caused by multiresistant bacteria; despite its effectiveness, its systemic use carries a risk of toxicity. GICSs appear to overcome this side effect, topically delivering high antibiotic concentrations to the wound and thus reducing the toxic-related events. Although several retrospective analyses and randomized controlled trials have studied the use of GICSs in cardiac surgery, conclusions regarding their efficacy in preventing sternal wound infection are inconsistent. We have reviewed the current literature focusing on high-risk patients

Antibiotic microbial assay using kinetic-reading microplate system

The aim of this study was to determine the optimal experimental conditions to develop a methodology for microbiological assay of apramycin employing microplate and kinetic reading mode, and to validate the developed method, through evaluation of parameters of selectivity, linearity, linear range, limits of detection and quantification, accuracy and precision. The turbidimetric assay principle is simple: the test solution is added to a suspension of test microorganism in culture media, the mixture is incubated under appropriate conditions and the microbial growth is measured by photometric reading. Microplate with kinetic reading mode employed in antibiotic assay is of considerable interest since it allows reduction of material and analysis time and enables a large number of samples to be analyzed simultaneously, with automated reading and calculating. Established conditions considered the standard-curve of apramycin at concentrations from 5.0 to 35.0 &#956;g mL-1, and tryptic soy broth inoculated with 5% Escherichia coli (ATCC 8739) suspension. Satisfactory results were obtained with 2 hours of incubation. The developed method showed appropriate selectivity, linearity in the range from 5.0 to 35.0 &#956;g mL-1, limits of detection and quantification of 0.1 and 0.4 &#956;g mL-1, respectively, as well as satisfactory accuracy (recuperation = 98.5%) and precision (RSD = 6.0%). Microplate assay combined the characteristics of microbiological (evaluation of antibiotic activity against sensitive test microorganism) and physico-chemical (operationally straightforward and faster results) assays.<br>O objetivo deste trabalho é determinar as condições experimentais ideais para o desenvolvimento de metodologia para a dosagem microbiológica de apramicina empregando microplacas e modo de leitura cinético e validar o método desenvolvido, através da avaliação dos parâmetros de especificidade e seletividade, linearidade, faixa ou intervalo linear, limite de detecção e quantificação, exatidão e precisão. O ensaio turbidimétrico é simples: a solução-teste é adicionada à suspensão de microrganismo-teste em meio de cultura, a mistura é incubada em condições apropriadas e o crescimento microbiano é medido por meio de leitura fotométrica. O emprego de método de microplacas com leitura cínética para a dosagem de antibióticos é de interesse considerável, uma vez que possibilita reduzir quantidade de material e tempo de análise necessários e permite o ensaio de grande número de amostras simultaneamente, com leitura e cálculo automatizados. As condições estabelecidas abrangem curva-padrão de apramicina com concentrações entre 5 e 35 &#956;g/mL, e emprego de meio de cultura caldo de triptona-soja inoculado com Escherichia coli (ATCC 8739) na proporção de 5%. Foram obtidos resultados satisfatórios após 2 horas de incubação. O método desenvolvido apresentou especificidade e seletividade adequadas, linearidade na faixa de 5 a 35 &#956;g/mL, limite de detecção e quantificação de 0,1 e 0,4 &#956;g/mL, respectivamente, exatidão (recuperação = 98,5%) e precisão (DPR = 6,0%) satisfatórias. O ensaio em microplaca agrega características dos ensaios microbiológicos (avaliação da atividade do antibiótico frente a microrganismo-teste sensível) e físico-químicos (facilidade operacional e maior rapidez na obtenção dos resultados)