Objective To shorten the turn around time of positive blood culture results by optimizing the blood culture positive specimen processing flow.Methods In January 26,2015,the microbiology department started the blood culture positive specimen processing flow optimization project,and applied the Lean Six Sigma method in the microbiological process management.The TAT data of 124 positive blood cultures containing Enterobacteriaceae were collected before and after the start of the project in about two months.We analyzed the turnaround time median,mean and standard deviation and reference Z value,process performance index,millions of error opportunities.We decompose the turnaround time into six time periods to find the key points of the process improvement and the influencing factors,and then put forward the reform measures to optimize the blood culture inspection process.MiniTab17.0 statistical software was used to process capability analysis and double sample t test.Results After the implementation of the project,the average turnaround time of the blood culture was shortened from 77.10 h to 64.03 h,improved by 13.06 h(16.94％).Process performance greatly improved in Ppk value increased from 0.49 to 0.88,the benchmark Z value increased from 1.48 to 2.63.After the improvement,except the positive alarm time of blood culture,the mean of the other decomposition time was significantly shorter than before.Conclusions The application of Six Sigma in process management can greatly improve the work efficiency and process performance.This project can save a lot of manpower,material and financial resources,reduce the waiting,shorten turnaround time,that achieve the desired results.

Objective: To discuss the application of matrix assisted laser desorption ionization time of flight mass spectrometry (MALDI-TOF MS) in the identification of Aspergillus and evaluate its performance. Methods: the clinical isolates of Aspergillus collected from May 2017 to March 2018 in PLA General Hospital were identified by VITEK MS V3.0 and the results were analyzed. The ITS sequencing resultswere used as the gold standard. Results: It identified 9 Aspergillus species (including 12 Aspergillus species in total) through the V3.0 database, accounting for 86.24% of the total clinical isolates. The identification rate by VITEK MS was 91.49% with 16.51% was not identified. The coincidence rate of genus was 93.62%, of which only two Aspergillus versicolor were identified to the level of the genus. According to the confidence level analysis, 88.30% of the strains obtained more than 99% of the identification rate. 13.83% of the strains did not have the identification results for the first time, with the error rate of 3.19%. After secondary extractions, the percentage of unidentified strain was reduced to 6.38%, and the identification error rate was reduced to 2.13%. Combined with traditional identification and VITEK MS identification, the correct rate of strains identification was 98.94% on genus level, and was 93.62% on species level. The influence of other fungi on Aspergillus identification was 0%. Conclusion As a powerful supplement to the traditional identification method, MALDI-TOF MS showed a lot of convenience when applied in the identification of Aspergillus, which improves the identification accuracy and the identification ability for fungi in laboratory.(Chin J Lab Med, 2018, 41: 577-582)

Objective:To evaluate the potential differential diagnostic value of QuantiFERON-TB Gold Plus(QFT-Plus) in patients with active tuberculosis (ATB) and latent tuberculosis infection (LTBI) people.Methods:Case-control study. A total of 108 healthcare workers and 30 ATB patients in Xi′an Chest Hospital were tested by QFT-Plus from April to November 2019, and the demographic characteristics were analyzed.Then, flow cytometry was used to analyze the relations between the QFT-Plus TB2-TB1 and the distribution of peripheral blood T lymphocyte subsets in ATB patients with positive culture results.Finally, with 34 QFT-Plus positive volunteers as LTBI group and 30 bacteriologically confirmed ATB patients as ATB group, the QFT-Plus new lyadded antigen and its potential differential diagnostic value between LTBI and ATB groups was evaluated by using the receiver operating curve (ROC).Results:In patients with ATB,QFT-plus TB2-TB1 was positively correlated with the proportion of CD8+T cells in peripheral blood T lymphocytes( r=0.586, P=0.004), negatively correlated with the proportion of CD4+ T cells( r=-0.511, P=0.015) and the ratio of CD4/CD8 ( r=-0.520, P=0.013).The peripheral blood TB2-TB1 in the ATB patients was significantly higher than that in the LTBI group[0.47(0.12,1.17) IU/ml versus 0.01(-0.08,0.22) IU/ml, U=233.5, P<0.001]. QFT-Plus TB2-TB1 can effectively distinguish ATB from LTBI, with an area under the ROC curve of 0.771 (95 %CI=0.653-0.889, P<0.001). Conclusion:QFT-Plus specific CD8 response (TB2-TB1) has the potential value to identify ATB from LTBI people.

Objective: To investigate the characteristics of hemolysis, resistance and homology of Staphylococcus cohnii urealyticum. Methods: A retrospective study was carried out on thirteen clinical strains of Staphylococcus cohnii urealyticum. They were re-identified by MALDI-TOF MS. Their colony and hemolytic characteristics on blood agar plates were observed. The co-hemolysis between Staphylococcus cohnii urealyticum and Staphylococcus aureus was demonstrated. The hemolysin genes and drug resistance genes were detected by PCR. Pulsed field gel electrophoresis and mass spectrometry were used to analyze the homology of strains. The susceptibility of strains to antimicrobial agents was detected by agar dilution. Results: The confirmed 13 strains of Staphylococcus cohnii urealyticum showed various levels of hemolysis and had enhanced synergistic hemolysis with Staphylococcus aureus. All strains were susceptible to vancomycin and tigecycline. There were 12 strains which carried mecA gene, 7 strains carried cfr gene, 7 strains carried ermC gene. The 13 strains were divided into 3 groups by MALDI-TOF MS, and 6 types by pulsed field gel electrophoresis. Conclusions Clinical strains of Staphylococcus cohnii urealyticum demonstrated various levels of hemolysis which could be enhanced by Staphylococcus aureus. Although they carried different drug resistance genes, they were all susceptible to vancomycin and tigecycline.