Search

Objective To analyze the serum polypeptide fingerprints of Enterococcus faecium (E. faecium) bloodstream infection in mice at different time points using matrix assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-FOF MS), screen differential polypeptide peaks, and create a corresponding diagnostic model and look for new markers. Methods Ninety ICR mice were used to establish E. faecium bloodstream infection model (including 10 mice as normal control group with PBS injection, and 80 mice as the infection group with 1/2 LD50 E. faecium injection in a volume of 0.1 ml/10 g by the intravenous tail). Blood samples were collected at 8 time points (1, 3, 6, 12, 24, 48, 96 and 128 h), and tested for IL-1α, IL-1β and IL-6 detection. Serum samples were then purified with weak cation magnetic beads, the serum polypeptide profiling was recognized by MALDI-TOF MS and BioExplorer software between infection group and normal control group. Amino acid sequences of the candidate polypeptides were identified by nano-liquid chromatography electrospray ionization-tandem mass spectrometry (nano- LC/ESI–MS/MS). Results After infected with E. faecium, the mice showed abnormal behaviors compared with the normal control group, including listless and reduced activity; IL-1α was down-regulated, while IL-1β and IL-6 were up-regulated. A total of 102 polypeptide peaks were detected by fingerprints analysis. Screening on the basis of 5 times difference in content in both infection group and control group, 8 polypeptides were higher in infection group than those in control group (P

Objective To analyze the fingerprints of serum polypeptides of mice infected with one of the five gram-negative bacteria through bloodstream by matrix assisted laser desorption-time of flight mass spectrometry (MALDI-TOF MS), identify the common polypeptide peaks, and establish the corresponding diagnostic model. Methods ICR mice were infected with Escherichia coli, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, and Proteus bloodstream, and then serum samples were collected. To profile serum polypeptides in the infected mice, MALDI-TOF MS was employed. The results were analyzed with BioExplorer software to compare the difference between infection group and control group. Results After infecting the Escherichia coli, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, and Proteus, there were 95, 104, 127, 115, and 103 polypeptide peaks found respectively. Comparing to the control group, the different polypeptide peaks were 73, 50, 99, 62, and 77 (P

Objective To establish a clinical method for early detection of the bloodstream infection bacteria based on matrix-assisted laser ionization time of flight mass spectrometry (MALDI-TOF MS). Methods After consulting the Laboratory Information System statistics and domestic related literature, We chose 10 kinds of bacteria (Escherichia coli., Pseudomonas aeruginosa, Acinetobacter baumannii, Klebsiella pneumoniae, Enterococcus faecium, Enterococcus faecalis, Staphylococcus aureus and Staphylococcus epidermidis, Proteus mirabilis, Streptococcus pneumoniae) as target. The MALDI-TOF MS was established using simulated bacterial infection blood samples. From March to May 2017, 33 blood samples of suspected sepsis patients from Emergency Department, General Hospital of PLA, were tested. Results The MALDI-TOF MS whose detecting sensitivity was 100CFU/ml had the same negative detection rate with the blood culture (27cases/27cases, 100%). Besides the 2 samples of Morganella morganii infection and Staphylococcus hominis infection were out of the range, the results of the remaining 4 positive samples were consistent (100%). Conclusion Compared to the blood culture and biochemical identification, MALDI-TOF MS can rapidly detect 10 kinds of bloodstream infection bacteria with high sensitivity and high accuracy. DOI: 10.11855/j.issn.0577-7402.2018.01.04

Objective To analyze the fingerprints of serum peptides in bloodstream infection induced by Candida albicans (C. albicans), with matrix assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS), and establish the corresponding diagnostic model. Methods To establish ICR mice model of C. albicans bloodstream infection, and collect the serum samples which were purified by weak cation exchange beads. The serum peptide finger printing was recognized by MALDI¬TOF MS, and BioExplorer software was used for analysis between infection group and normal control group. Furthermore, the peptide fingerprints were analyzed between C. albicans infection group, Escherichia coli (E. coli) infection group and Staphylococcus aureus (S. aureus) infection group. Results Comparison between C. albicans infection group and normal control group, there were 135 polypeptide peaks, of which 5 polypeptides up-regulated, 6 down-regulated and 7 up-regulated first and down-regulated afterwards. The diagnostic model was established by combination of 6 peaks (i.e. m/z 1610.9, 1742.3, 2666.4, 2778.0, 3345.1 and 4528.8), which possessed an accurate rate of 80.0% in diagnosis of C. albicans infection. It was found by comprehensive comparison between C. albicans, E. coli and S. aureus infection groups that there were 5 polypeptides expressed collectively, i.e. m/z1513.8, 2910.8, 3538.1, 3884.9 and 5007.3. Conclusions MALDI-TOF MS can be used to distinguish the C. albicans infection and normal polypeptide peaks. The collective polypeptides expressed in the infection groups can be further used to diagnose the infection. Establishment of corresponding diagnostic models may be helpful for early diagnosis of fungal bloodstream infection and provide a basis for reasonable clinical medication. DOI: 10.11855/j.issn.0577-7402.2018.01.05

Objective To study the serum peptide fingerprint using matrix-assisted laser desorption ionization time of flight mass spectrometry (MALDI-TOF MS) technology, and find the different peaks with potential significance and establish the diagnosis model of Staphylococcus aureus and Escherichia coli bloodstream infection. Methods To establish ICR mice model of S. aureus and E. coli bloodstream infections, and collect serum samples. The serum samples were purified by weak cation exchange beads, the serum peptide fingerprint was recognized by using MALDI-TOF MS and BioExplorer software between infections group and normal control group. Results Compared with the normal control group, 6 peptides were up-regulated, 7 peptides down- regulated and 8 peptides up-regulated first and then down-regulated in S. aureus infection group; And 5 peptides down-regulated, 4 peptides down-regulated first and then up-regulated, and 8 peptides up-regulated first and then down-regulated in E. coli infection group. Conclusion MALDI-TOF MS combined with BioExplorer software may be used as a tool to study the serum peptides of S. aureus and E. coli bloodstream infection, effectively find significant peptides for establishing a diagnosis model of these two bacterial infections, and has a certain value for the diagnosis of bacterial bloodstream infection. DOI: 10.11855/j.issn.0577-7402.2017.05.08