Effect of freezing and storage temperature on stability and antimicrobial activity of an antibiotic mixture used for decontamination of tissue allografts.

One of the most important risks to be controlled in tissue banking is the infection associated with the clinical use of auto- and allografts. Thus, tissue disinfection protocols are used, in addition to processing in controlled environments. For this purpose, combinations of antibiotics are designed to ensure a broad spectrum of antimicrobial activity. This type of protocol is usually validated by testing its antimicrobial efficacy. In this work, we have studied the effect of several factors on the potential of an antibiotic mixture: container, freezing, storage at 4 °C, storage at - 30 °C and storage at - 80 °C. The molecular stability of the compounds has also been tested, additionally to their efficacy. Our findings show that storage conditions affect the molecular stability of Fungizone and Tobramycin (only in case of frozen storage for the last one). Nevertheless, the solution retains its antimicrobial activity for several weeks. The availability of stored aliquots of disinfectant solution and defining expiry dates for different storage conditions can help to schedule tissue bank tasks.

Evaluación del antígeno galactomanano y la PCR en tiempo real de Aspergillus para el diagnóstico de aspergilosis invasiva / Evaluation of galactomannan antigen and Aspergillus real time PCR for diagnosis of Invasive Aspergillosis

Introducción. Comparar las pruebas de antígeno galactomanano (AG) y moleculares (PCRrt) con el cultivo para el diagnóstico de aspergilosis invasiva (AI). Material y métodos. Se analizaron 472 muestras: 388 respiratorias, 84 sueros, de 271 pacientes. En las respiratorias se realizó cultivo y AG y en los sueros AG. En caso de discordancia entre ellas se realizó PCR. Resultados. El AG resultó positivo en 22 sueros de 84, 21 tenían esta prueba positiva en muestra respiratoria. De 62 sueros con AG negativo, 45 fueron también negativas en muestras respiratorias. El cultivo fue positivo en 37, coincidiendo todas con AG positivo. Comparando cultivo con AG, éste mostró un VPP= 23%, VPN=100%, S= 100% y E=52%. La PCRrt respecto al cultivo mostró un VPP= 69%, VPN= 89%, S= 64% y E= 82%. En los sueros entre AG y PCR encontramos 60% de discrepancias. Conclusiones. Consideramos muy útil la detección de AG en suero combinada con cultivo y AG en muestras respiratorias para el diagnóstico de AI, precisando PCRrt más estudios para su estandarización y establecer puntos de corte (AU)

Introduction. The aim of the study was to compare the galactomannan antigen (GA) and molecular biology (PCRrt) tests with the culture in the diagnosis of invasive aspergillosis (IA). Material and methods. Four hundred and seventy two samples were analyzed: 388 respiratory and 84 serum samples from 271 patients. Culture and GA were evaluated in the respiratory samples and GA in the serum samples. PCR was used when discrepancies were observed among culture and GA tests. Results. The detection of GA in serum was positive in 22 (of 84), 21 had the test positive respiratory sample. Of the 62 sera with negative GA, 45 were also negative respiratory specimens. The culture was positive in 37 of which were positive for GA. Comparing culture with AG, it showed PPV=23%, NPV=100%, S=100% and E=52%. The PCR showed respect to culture: PPV=69%, NPV=89%, S=64% and E=82%. In sera were found in 60% discrepancies between PCRrt and GA. Conclusions. We consider useful the GA detection in serum combined with culture and GA in respiratory samples, for diagnosis of AI. PCR requires further studies for standardization and set breakpoints (AU)