Performance evaluation and clinical validation of optimized nucleotide MALDI-TOF-MS for mycobacterial identification.

Objective: To evaluate the performance and validate the diagnostic value of a nucleotide matrix-assisted laser desorption time-of-flight mass spectrometry (MALDI-TOF-MS) with the analysis process optimized in identification of mycobacterium species. Methods: The optimized analysis process was used for mycobacterial identification in the nucleic MALDI-TOF-MS. 108 samples were used for assessing the performance of nucleic MALDI-TOF-MS, including 25 reference standards, 37 clinical isolates, 37 BALF, and 9 plasmids. The BALF of 38 patients suspected of pulmonary mycobacterial infection was collected for validation. Clinical etiological diagnosis was used as the gold standard to evaluate the diagnostic value of nucleotide MALDI-TOF-MS. Results: The sensitivity, specificity, and accuracy of the nucleotide MALDI-TOF-MS in mycobacterial identification were 96.91%, 100% and 97.22%, respectively, and the limit of detection for mycobacterium tuberculosis (MTB) was 50 bacteria/mL. Among 38 patients suspected of pulmonary mycobacterial infection, 33 were diagnosed with pulmonary tuberculosis infection, and 5 with non-mycobacterial infection. In clinical validation, the positive rates of MALDI-TOF-MS, Xpert MTB/RIF, culture and AFS in BALF of patients diagnosed with tuberculosis infection were 72.7%, 63.6%, 54.5% and 27.3%, respectively. The sensitivity/specificity of MALDI-TOF-MS, Xpert, culture and AFS in diagnosing MTB were 72.7%/100%, 63.6%/100%, 54.5%/100%, 27.3%/100%, with the areas under the curve of 0.864, 0.818, 0.773, and 0.636, respectively. Conclusion: Optimized nucleotide MALDI-TOF-MS has satisfactory sensitivity, specificity and low LOD in the identification of mycobacteria, which may serve as a potential assay for mycobacterial identification.

RecurIndex assay as an aid for adjuvant chemotherapy decisions in HR-positive HER2-negative breast cancer patients.

Background: Adjuvant chemotherapy is a major adjuvant treatment modality for hormonal receptor (HR)-positive and HER2-negative early breast cancer, but only 2%-20% of patients derive practical benefits. How to balance its potential benefits and risks becomes a challenging clinical problem. The purpose of this study was to assess whether RecurIndex assay could serve as an aid for adjuvant chemotherapy decisions in Chinese patients with HR-positive HER2-negative early breast cancer. Methods: The tissue samples of pT1-2N0 HR-positive HER2-negative breast cancer from multiple centers were detected using RecurIndex assay, based on which the patients were assigned into low- and high-risk groups. The survival outcomes of low- and high-risk patients including those with and without adjuvant chemotherapy were compared, and the risk factors for recurrence and metastasis were identified. Results: Totally 445 patients were eligible for analysis. By contrast to high-risk patients, low-risk patients represented better 7-year recurrence-free survival (RFS), distant recurrence-free survival (DRFS) and local recurrence-free survival (LRFS) rates. For low-risk patients, no significant differences were shown between those with and without adjuvant chemotherapy in 7-year RFS, DRFS and LRFS rates. These differences were also inapparent between high-risk patients with and without adjuvant chemotherapy. The multivariate model revealed high-risk patients had a significantly elevated risk of recurrence and metastasis than those at low risk. Conclusion: HR-positive HER2-negative early breast cancer patients at low risk stratified by RecurIndex assay might be exempt from adjuvant chemotherapy. Whether adjuvant chemotherapy may derive survival benefits for high-risk patients still needs larger cohorts to verify.

Very high gravity ethanol and fatty acid production of Zymomonas mobilis without amino acid and vitamin.

Very high gravity (VHG) fermentation is the mainstream technology in ethanol industry, which requires the strains be resistant to multiple stresses such as high glucose concentration, high ethanol concentration, high temperature and harsh acidic conditions. To our knowledge, it was not reported previously that any ethanol-producing microbe showed a high performance in VHG fermentations without amino acid and vitamin. Here we demonstrate the engineering of a xylose utilizing recombinant Zymomonas mobilis for VHG ethanol fermentations. The recombinant strain can produce ethanol up to 136 g/L without amino acid and vitamin with a theoretical yield of 90 %, which is significantly superior to that produced by all the reported ethanol-producing strains. The intracellular fatty acids of the bacterial were about 16 % of the bacterial dry biomass, with the ratio of ethanol:fatty acids was about 273:1 (g/g). The recombinant strain was achieved by a multivariate-modular strategy tackles with the multiple stresses which are closely linked to the ethanol productivity of Z. mobilis. The over-expression of metB/yfdZ operon enabled the growth of the recombinant Z. mobilis in a chemically defined medium without amino acid and vitamin; and the fatty acids overproduction significantly increased ethanol tolerance and ethanol production. The coupled production of ethanol with fatty acids of the Z. mobilis without amino acid and vitamin under VHG fermentation conditions may permit a significant reduction of the production cost of ethanol and microbial fatty acids.