Objective To understand the epidemic trend and drug susceptibility of pathogenic bacteria in children with lower re-spiratory tract infection to provide the basis for clinical rational drug use.Methods The sputum culture specimens in these two hospitals during 2013 were performed the pathogenic bacterial culture and the drug susceptibility test respectively.The results were conducted the comparative analysis.Results 6124 strains of bacteria were isolated from the children lower respiratory tract sputum specimens in our hospital during 2013,including 5 121 strains of Gram negative bacteria,accounting for 62.7%,which were domina-ted by Haemophilus influenzae,Klebsiella pneumoniae,Escherichia coli,Bauman Acinetobacter and Pseudomonas aeruginosa;Gram positive bacteria were 2734 strains,accounting for 33.5%,the top two were Streptococcus pneumoniae and Staphylococcus aureus;311 strains of fungi,accounting for 3.8%,and Candida albicans was predominant.1600 strains of bacteria were isolated from the lower respiratory tract sputum specimens in Nanjing Brain Hospital during 2013,including 1 134 strains of Gram negative bacteria, accounting for 70.9%,which were dominated by Klebsiella pneumoniae,Escherichia coli,Pseudomonas aeruginosa and Acinetobact-er Bauman;296 strains of Gram positive bacteria,accounting for 18.5%,Staphylococcus aureus was predominant;170 strains of fungi,accounting for 10.6%,Candida albicans was predominant.The sensitive drugs to Gram-negative bacilli were piperacillin /tazobactam and imipenem,while the sensitive drugs to Gram-positive bacilli were linezolid and vancomycin.Conclusion The Gram negative bacteria are the main pathogens of lower respiratory infection in children,and strengthening bacterial culture and drug re-sistance monitoring is necessary for rational use of antibacterial drugs.

Objective:To analyze the effects of two decomposition algorithms of dual-energy cone beam CT (DECBCT) (direct decomposition and iterative decomposition) on the image quality and material decomposition accuracy of different sizes of phantoms.Methods:Different sizes of imaging parts of patients were simulated using the combination of CatPhan604 phantoms and customized annuluses. CBCT with high energy of 140 kVp and low energy of 100 kVp were acquired using the Varian Edge CBCT system. Then the material decomposition of DECBCT images was performed using the two algorithms. The electron density (ED) and contrast-to-noise ratio (CNR) of each material in the CTP682 module were calculated. They were used to assess the decomposition accuracy and image quality of the two algorithms.Results:Based on the values in the Catphan604 manual, both algorithms have high ED accuracy. Only the ED accuracy of four materials of the smallest sized phantom showed statistical difference ( z = -4.21, 4.30, 2.87, 5.45, P < 0.05), but the average relative error was less than 1%. The CNR of the iterative decomposition algorithm was significantly higher than that of the direct decomposition, increasing by 51.8%-703.47%. The increase in the phantom size significantly reduced the accuracy of ED, and the increased amplitude of the relative error was up to a maximum of 2.52%. The large phantom size also reduced the image quality of iterative decomposition, and the decreased amplitude of CNR was up to a maximum of 39.71. Conclusions:Compared with the direct decomposition, the iterative decomposition algorithm can significantly reduce the image noise and improve the contrast without losing the accuracy of electron density in the DECBCT construction of different sizes of phantoms.