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The aim of this study was to evaluate procalcitonin (PCT) diagnostic accuracy in discriminating gram-negative (GN) from gram-positive (GP) bloodstream infections and determining the relationship between PCT levels, infection sites, and pathogen types.Clinical and laboratory data were collected from patients with blood culture (BC)-positive sepsis between January 2014 and December 2015. PCT levels at different infection sites were compared, as was the presence of GN and GP bloodstream infection. A receiver operating characteristic (ROC) curve was generated to assess diagnostic accuracy.Of the 486 monomicrobial BCs, 254 (52.26%) were positive for GN bacteria (GNB), and 202 (42.18%) for GP bacteria (GPB). Median PCT levels were higher in BCs positive for GN (2.42ng/ml, IQR: 0.38-15.52) than in those positive for GPB (0.49ng/ml, IQR: 0.13-5.89) (P0.001). In the ROC analysis to differentiate between GNB and GPB, the area under the curve was 0.628 (95% CI: 0.576-0.679). When the cutoffs for PCT were 10.335 and 15.000ng/ml, the specificity of GNB infection was 80.2% and 84.2%, respectively. PCT levels caused by GNB differed between Escherichia coli and Acinetobacter baumanni/Burkholderia cepacia, Klebsiella pneumonia and Acinetobacter baumanni. PCT levels caused by GPB differed between Staphylococcus epidermidis/Staphylococcus aureus and Staphylococcus hominis/Staphylococcus haemolyticus, Enterococcus faecium and Enterococcus faecalis/S.hominis/S. haemolyticus. Among patients with known infection sites, there were statistical differences in PCT levels between abdominal infection and pneumonia/infective endocarditis, urinary tract infection and pneumonia/catheter-related infection/infective endocarditis.PCT can distinguish between GNB and GPB infection, as well as between different bacterial species and infection sites.

Here, we report the synthesis of aligned carbon nanotube (CNT) bundles with adjustable arrays by a non-lithographic and low-cost strategy. A polystyrene/ferrocene patterns on silicon (Si) substrate was prepared through controlled mesoscopic dewetting of dilute polystyrene/ferrocene solution. A variety of regular patterns, including ladder, stripe and scale, were synthesized simply by changing the solution concentration. Ultraviolet (UV) irradiation effectively cross-linked polymer skeleton and made it suitable for structure-directing agent. In the sequent pyrolysis, polystyrene skeleton was decomposed and ferrocene was converted into the skeleton of inorganic patterns simultaneously. Aligned CNT bundles guided by the catalytically functionalized inorganic patterns were initiated to grow. This methodology opens up a new avenue for fabricating CNT arrays in a simple and controllable manner.

National Basic Research 973 Program of China [2011CB935901]; National Nature Science Foundation of China [21031004, 21021061]