Application of matrix-assisted laser desorption ionization time-of-flight mass spectrometry in the screening of vanA-positive Enterococcus faecium.

In order to evaluate a rapid matrix-assisted laser desorption ionization-time of flight mass spectrometry (MAIDI-TOF MS) assay in screening vancomycin-resistant Enterococcus faecium, a total of 150 E. faecium clinical strains were studied, including 60 vancomycin-resistant E. faecium (VREF) isolates and 90 vancomycin-susceptible (VSEF) strains. Vancomycin resistance genes were detected by sequencing. E. faecium were identified by MALDI-TOF MS. A genetic algorithm model with ClinProTools software was generated using spectra of 30 VREF isolates and 30 VSEF isolates. Using this model, 90 test isolates were discriminated between VREF and VSEF. The results showed that all sixty VREF isolates carried the vanA gene. The performance of VREF detection by the genetic algorithm model of MALDI-TOF MS compared to the sequencing method was sensitivity = 80%, specificity = 90%, false positive rate =10%, false negative rate =10%, positive predictive value = 80%, negative predictive value= 90%. MALDI-TOF MS can be used as a screening test for discrimination between vanA-positive E. faecium and vanA-negative E. faecium.

[Risk factors for acquired multidrug-resistant Acinetobacter baumannii colonization in respiratory intensive care unit].

OBJECTIVE: To determine the risk factors for respiratory intensive care unit (RICU)-acquired colonization of multidrug-resistant Acinetobacter baumannii (MDR-AB). METHODS: From January 2010 to June 2011, active screening was performed to define patients with RICU-acquired colonization of MDR-AB. And environment surveillance was carried out and patient data were collected. Logistic regression was applied to identify the risk factors of RICU-acquired colonization of MDR-AB. RESULTS: Active screening for MDR-AB was performed for 110 patients in RICU and 50 patients turned out to be positive. After eliminating 3 input positive patients, the RICU-acquired colonization rate of MDR-AB was 43.9% (47/107). The environmental contaminated rate of MDR-AB was 66.0% (31/47) for 47 positive patients and 33.9% (19/56) for 56 negative ones (χ(2) = 10.494, P < 0.01). Five risk factors were associated with the colonization of MDR-AB through univariate analysis: consciousness disturbance, use of carbapenems, nasal feeding tube, endotracheal intubation and mechanical ventilation (all P < 0.05). The Logistic regression equation contained 3 risk factors of conscious disturbance, use of carbapenems and mechanical ventilation (OR = 3.412, 3.211, 3.002; 95% CI: 1.165 - 9.992, 1.117 - 9.233, 1.101 - 8.182). CONCLUSION: Three risk factors are independently associated with the RICU-acquired colonization of MDR-AB: consciousness disturbance, use of carbapenems and mechanical ventilation.

[Correlation factor analysis of pan-drug resistant Acinetobacter baumannii strains in acquired infections].

OBJECTIVE: To explore the clinical factors, drug resistance and molecular epidemiology homologous characteristics of pan-drug resistant Acinetobacter baumannii (PDRAB) in acquired infections and analyze the correlation factor between epidemic characteristics and acquired infections. METHODS: A total of 60 PDRAB strains from nine acquired infections and related clinic data were collected from January 2009 to January 2011. The drug-resistant phenotype was tested by disk diffusion methods. The isolate identification and homology were studied by automation repetitive-element sequence-based (REP)-PCR typing platform from genes and matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF-TOF MS) from proteins. RESULTS: All strains were resistant to 12 antibiotics except 2 strains to imipenem and meropenem. The strains in this study were divided into 12 types (A-L) by REP-PCR. And 60 strains were also clustered to a-e types by MALDI-TOF-TOF MS. Compared with MALDI-TOF-TOF MS, REP-PCR tended to be more accurate. Breathing machine carriage and cross transmission were the main reasons for a major epidemic outbreak at department of pulmonary medicine from July 2009 to October 2009. Hand transmission of medical care personnel was a key factor for SICU 2010 January to February. The contamination and transmission to environment of PDRAB in nasal pharynx or respiratory tract by superspreader were the main reasons for the other 7 epidemic outbreaks. Department of emergency medicine was the source of acquired infections. CONCLUSION: The key control measures of acquired infections are early identification and isolation of spreader, environment and instrument disinfection, hand washing and rational uses of antibiotics. MALDI-TOF-TOF MS will become a preferred tool of identification and classification of microorganisms because of its simple operation, affordable price and handling rapidity.

Gene therapy of malignant solid tumors by targeting erbB2 receptors and by activating T cells.

One of the strategies to improve the outcome of anti-erbB2-mediated immunotherapy is to combine anti-erbB2 antibodies with T-cell-based adoptive immunotherapy, which can be achieved by expressing anti-erbB2 mAb on the surface of T cells. A single-chain variable fragment (scFv) from an anti-erbB2 mAb has been expressed on T cell surface to bind to erbB2-positive cells, and CD3ζ has been expressed as a fusion partner at C terminus of this scFv to transduce signals. T cells grafted with this chimeric scFv/CD3ζ were able to specifically attack target tumor cells with no MHC/Ag restriction. To test the effects of CD28 signal on cellular activation and antitumor effectiveness of chimeric scFv/CD3ζ-modified T cells, we constructed a recombinant anti-erbB2 scFv/Fc/CD28/CD3ζ gene in a retroviral vector. T cells expressing anti-erbB2 scFv/Fc/CD28/CD3ζ specifically lyzed erbB2-positive target tumor cells and secreted not only interferon-γ (IFN-γ) but also IL-2 after binding to their target cells. Our data indicate that CD3 and CD28 signaling can be delivered in one molecule, which is sufficient for complete T cell activation without exogenous B7/CD28 co-stimulation.

[SOCS1 knockdown sensitize anti-tumor activity of IFN-alpha2a-NGR].

AIM: Search for key molecules to influence the tumor-targeted IFN-alpha2a-NGR anti-tumor sensitivity through signaling pathway study. Try to enhance the antitumor efficacy of IFN-alpha2a-NGR. METHODS: MTT method was used to determine the growth inhibitory effects of IFN-alpha2a-NGR on A549 and MKN-45 cells. Flow cytometry and Western blot were employed to detect the expression of STAT1, p-STAT1, p53, OAS and SOCS1; SOCS1 gene knock down was carried out by synthesized siRNA. RESULTS: When stimulated with IFN-alpha2a-NGR, the increased expression of STAT1, p-STAT1, p53, OAS and SOCS1 were observed in A549 cells, but only SOCS1 was notably increased in MKN-45 cells. The proliferation inhibition ability of MKN-45 to IFN-alpha2a-NGR was promoted by SOCS1 knocking down. (the inhibition rate was enhanced from 14.69%+/-1.05% to 36.97%+/-2.05%). CONCLUSION: This study has further demonstrated that there were no differences on antitumor effects between IFN-alpha2a-NGR and IFN-alpha2a on cell or molecular level. Besides interferon-alpha receptor (IFNAR) which has been demonstrated before, p-STAT1, p53 and SOCS1 were important determinants of tumor resistance to IFNs therapy. The antitumor efficacy of IFN-alpha2a-NGR can be enhanced by RNA interference. These results might be helpful for the further development of IFN-alpha2a-NGR.