Effects of Different Sample Parts and Sterilization Methods on Contamination and Survival Rates of Shoots with Buds in Chinese Chestnut

In this study,we investigated the preferable explant types and sterilization method for tissue culture in Chinese chestnut,in order to provide a technical support for the asexual reproduction of Chinese chestnut.The base,middle and apex parts of annual shoots with buds in Chinese chestnut were sampled and cut to 2-3 cm stem segments each with one bud,then sterilized orderly with different duration in 2%NaClO plus 0.1%HgCl_(2)solutions.The results indicated that the duration of 2%NaClO for 20 min+0.1%HgCl_(2)for 15 min exerted an effective disinfection property on the middle parts of annual shoots with buds,and achieved a contamination rate under 5%and a survival rate over 90%.

Blood collection procedures influence contamination rates in blood culture： a prospective study

Background Blood culture contamination is a significant adverse event. The aim of this project was to evaluate the efficacy of a strict blood collection procedure in reducing the blood culture contamination rate. Methods A prospectively controlled study was performed in two different medical areas in Peking Union Medical College Hospital （PUMCH） for 16 months （from May 2006 to September 2007）. In test group, a strict blood collection procedure was carried out by trained nurses with the veinpuncture sites were scrupulously disinfected with 2.5% tincture of iodine plus 70% alcohol. In control group, commonly used procedure in PUMCH was performed with 0.45% chlorhexidine acetate plus 0.2% iodine. Blood culture positive results for 4 target organisms （Coagulase-negafive staphylococci, Propionibacterium acnes, physicians from infectious department to （contamination）. Corynebacterium species and Bacillus determine whether a sample was true species） were further assessed by positive （pathogen） or false positive Results Total 9321 blood culture collections were analyzed. The blood culture contamination rate in test group was significantly lower than that in control group （5/3177 （0.16%） vs. 77/6144 （1.25%）; x2=13.382, P 〈0.001）. The most common contaminant was Coagulase-negative staphylococcus （76.83%）. The average cultural time during which contaminated samples became positive was longer than that for true pathogen samples （42.0 hours vs. 13.9 hours, P=-0.041）. Conclusion Using a strict blood collection procedure can significantly reduce blood culture contamination rate.