Acinetobacter baumannii. ¿Un oportunista fuera de lugar? / Acinetobacter baumannii. An opportunistic pathogen offside?

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Estudio in vitro de las propiedades antimicrobianas de una espuma de poliuretano que libera iones de plata / In vitro study of the antimicrobial properties of a silver ion–releasing polyurethane foam

Objetivos: Evaluar las propiedades antimicrobianas de una espuma de poliuretano que libera iones de plata sobre diversos microorganismos. Se estudia la difusión al medio de Ag+, así como la posible citotoxicidad sobre células humanas. Material y métodos Estudio de liberación de plata de V.A.C. GranuFoam Silver® mediante espectrometría de masas (Inductively Coupled Plasma Mass). Estudio experimental in vitro para evaluar la capacidad bactericida mediante curvas de letalidad sobre A. baumannii, P. aeruginosa, S. maltophilia, K. pneumoniae, E. coli, P. mirabilis, S. aureus resistente a meticilina, E. faecium, S. pyogenes y C. minutissimum. Estudio de citotoxicidad sobre fibroblastos humanos. Resultados La liberación de Ag+ muestra una curva exponencial con una fase estable de meseta a partir de las 3h, con niveles de 0,22-0,24mg/l. En 3h se logró una reducción superior al 99,9% en todos los gramnegativos excepto en E. coli que fue del 92,5%. La reducción fue superior al 99% a las 2h en S. pyogenes y C. minutissimum, a las 6h en S. aureus y a las 14h en E. faecium. En simulación in vivo estas reducciones se alcanzaron en 6h en los gramnegativos y en 24h en los grampositivos. Las concentraciones de Ag+ no fueron citotóxicas sobre fibroblastos humanos, sin observar diferencias entre las células expuestas a Ag+ y los controles (p = 0,7).Conclusión V.A.C. Granufoam Silver® liberó concentraciones bactericidas de Ag+ que no fueron perjudiciales para los fibroblastos humanos. Se presenta como una buena alternativa para el control y prevención local de las infecciones (AU)

Introduction: The antimicrobial properties of a silver ion (Ag+)-releasing polyurethane foam were evaluated using different microorganisms. The diffusion of Ag+ from the medium, aswell as any possible cytotoxicity on human cells, was also studied. Material and methods: Silver release from V.A.C. Granu Foam Silver1 was assessed by using inductively coupled plasma mass spectrometry (ICP-MS). An in vitro experimental study was designed to evaluate the bactericide capacity using lethal dose curves on A. baumannii,P. aeruginosa, S. maltophilia, K. pneumoniae, E. coli, P. mirabilis, methicillin resistant S. aureus,E. faecium, S. pyogenes and C. minutissimum. A cytotoxicity study was also performed on human fibroblasts. Results: The silver release showed an exponential curve with a stable meseta phase after 3 hours, with levels of 0.22-0.24 mg/l. A reduction of 99.9% of all the gram-negatives was achieved at 3 hours. The reduction was greater than 99% at 2 hours in S. pyogenes and C. minutissimum, at 6 h in S. aureus and at 14 h in E. faecium. In an in vivo simulation model, these reductions were achieved in 6 hours in the gram negatives and 24 h inthe gram positives. The silver concentrations were no cytotoxic to human fibroblasts, with no differences being observed between the cells exposed to Ag+ and the controls(p = .7)Conclusion: V.A.C. Granufoam Silver1 releases bactericide concentrations of Ag+ that did not damage human fibroblasts. It appears to be a good alternative for the control and prevention of local infections (AU)

Pulmonary nocardiosis: risk factors and outcomes.

BACKGROUND AND OBJECTIVES: Pulmonary nocardiosis (PN) is an infrequent but severe infection caused by Nocardia spp., which can behave either as opportunistic or primary pathogens. The present study identifies the risk factors for PN, clinical symptoms and radiographic features and the factors that affect its prognosis. METHODS: An observational study of all the patients diagnosed with PN over a 13-year period at the authors' institution. RESULTS: Thirty-one adult patients were identified with PN, 11 of whom had disseminated nocardiosis. The predisposing conditions were COPD (23%), transplantation (29%), HIV infection (19%), alcoholism (6.5%) and treatment with steroids (64.5%). Respiratory tract sampling using non-invasive techniques had a diagnostic yield of 77%, while specimens from invasive methods had a yield of 47%. Mean time to diagnosis was 42 days. Dissemination to the central nervous system was related to alcoholism. The mortality rates were 41% for PN and 64% for disseminated nocardiosis; when Nocardia disseminated to the central nervous system, the mortality was 100%. CONCLUSION: Specific risk factors were found in 94% of patients, with the most common being corticosteroid treatment and immunosuppressive therapy. The time to reach diagnosis and to prescribe specific treatment was considerable and mandatory assessment for nocardia in high-risk patients is required. The mortality rate of PN is high and early diagnosis and treatment are needed. Medications other than co-trimoxazole may be required.