Objective:To explore the feasibility of rapid detection of AAC(6′)-Ⅰb-cr enzyme-producing Enterobacteriales using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS). Methods:A total of 55 Enterobacteriales strains isolated from the Department of Clinical Laboratory of Wenzhou TCM Hospital from January to July 2022 were collected. Ciprofloxacin and norfloxacin solutions were used as reaction substrates, incubated with the test strains for 1 hour, followed by centrifugation, and the supernatant was detected by MALDI-TOF MS. In addition, 128 clinical strains isolated from the clinical laboratory of our hospital from March to May 2023 were prospectively collected for the validation study of the method. Results:After ciprofloxacin and norfloxacin were acetylated by the AAC(6′)-Ⅰb-cr enzyme, a mass shift of relative molecular mass 42 occurred, resulting in the appearance of three mass spectral peaks representing the acetylated drugs. No such peak was observed in enzyme-negative strains. Besides, compared with gene sequencing results, the MALDI-TOF MS results of 128 strains used in the validation test showed 100% both in specificity and sensitivity.Conclusion:MALDI-TOF MS can rapidly and accurately detect AAC(6′)-Ⅰb-cr enzyme-producing Enterobacteriaceae bacteria.

Objective:To explore the feasibility of rapid detection of AAC(6′)-Ⅰb-cr enzyme-producing Enterobacteriales using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS). Methods:A total of 55 Enterobacteriales strains isolated from the Department of Clinical Laboratory of Wenzhou TCM Hospital from January to July 2022 were collected. Ciprofloxacin and norfloxacin solutions were used as reaction substrates, incubated with the test strains for 1 hour, followed by centrifugation, and the supernatant was detected by MALDI-TOF MS. In addition, 128 clinical strains isolated from the clinical laboratory of our hospital from March to May 2023 were prospectively collected for the validation study of the method. Results:After ciprofloxacin and norfloxacin were acetylated by the AAC(6′)-Ⅰb-cr enzyme, a mass shift of relative molecular mass 42 occurred, resulting in the appearance of three mass spectral peaks representing the acetylated drugs. No such peak was observed in enzyme-negative strains. Besides, compared with gene sequencing results, the MALDI-TOF MS results of 128 strains used in the validation test showed 100% both in specificity and sensitivity.Conclusion:MALDI-TOF MS can rapidly and accurately detect AAC(6′)-Ⅰb-cr enzyme-producing Enterobacteriaceae bacteria.

Objective We propose a low-dose CT reconstruction method using partial differential equation (PDE) denoising under high-dimensional constraints. Methods The projection data were mapped into a high-dimensional space to construct a high-dimensional representation of the data, which were updated by moving the points in the high-dimensional space. The data were denoised using partial differential equations and the CT image was reconstructed using the FBP algorithm. Results Compared with those by FBP, PWLS-QM and TGV-WLS methods, the relative root mean square error of the Shepp-Logan image reconstructed by the proposed method were reduced by 68.87％, 50.15％ and 27.36％, the structural similarity values were increased by 23.50％, 8.83％ and 1.62％, and the feature similarity values were increased by 17.30％, 2.71％ and 2.82％, respectively. For clinical image reconstruction, the proposed method, as compared with FBP, PWLS-QM and TGV-WLS methods, resulted in reduction of the relative root mean square error by 42.09％, 31.04％and 21.93％, increased the structural similarity values by 18.33％, 13.45％ and 4.63％, and increased the feature similarity values by 3.13％, 1.46％ and 1.10％, respectively. Conclusion The new method can effectively reduce the streak artifacts and noises while maintaining the spatial resolution in reconstructed low-dose CT images.

Objective We propose a low-dose CT reconstruction method using partial differential equation (PDE) denoising under high-dimensional constraints. Methods The projection data were mapped into a high-dimensional space to construct a high-dimensional representation of the data, which were updated by moving the points in the high-dimensional space. The data were denoised using partial differential equations and the CT image was reconstructed using the FBP algorithm. Results Compared with those by FBP, PWLS-QM and TGV-WLS methods, the relative root mean square error of the Shepp-Logan image reconstructed by the proposed method were reduced by 68.87％, 50.15％ and 27.36％, the structural similarity values were increased by 23.50％, 8.83％ and 1.62％, and the feature similarity values were increased by 17.30％, 2.71％ and 2.82％, respectively. For clinical image reconstruction, the proposed method, as compared with FBP, PWLS-QM and TGV-WLS methods, resulted in reduction of the relative root mean square error by 42.09％, 31.04％and 21.93％, increased the structural similarity values by 18.33％, 13.45％ and 4.63％, and increased the feature similarity values by 3.13％, 1.46％ and 1.10％, respectively. Conclusion The new method can effectively reduce the streak artifacts and noises while maintaining the spatial resolution in reconstructed low-dose CT images.

Objective To analyze the genotype and plasmid transfer of Enterobacteriaceae carring blaNDM‐1 with blaIMP‐4 or blaKPC‐2 .Methods From April 2012 to October 2014 ,a total of 33 non‐repeatitive carbapenem‐resistant Enterobacteriaceae ( including Imipenem‐resistant , meropenem‐resistant or Ertapenem‐resistant) were isolated from 5 hospitals in Wenzhou and Hangzhou . Identification and antimicrobial susceptibility test were performed using Vitek 2 Compact automatic microbiology analyzer . Phenotypes of carbapenemase were screened using modified Hodge test and ethylenediamine tetraacetic acid‐disk synergy test .Extended spectrum βlactamase test was determined by the double disk combination test which was recommended by Clinical and Laboratory Standards Institute .AmpC activity was tested by a three‐dimensional Cefoxitin method .Drug resistant genes including blaNDM‐1 and linkage of ISAba125‐NDM were detected by polymerase chain reaction (PCR) .The purified PCR products were cloned and sequenced .Plasmid conjugation experiment and elimination method were carried out to test partial bacterial strain and K . pneumoniae carrying blaNDM‐1 with blaIMP‐4 or blaKPC‐2 .Results Of the 33 non‐repeatitive carbapenem‐resistant Enterobacteriaceae ,28 were strains of K .pneumoniae ,1 strain of K . oxytoca,2strainsof Escherichiacoli,1strainof K.planticolaand1strainof E.cloacae.Thirteenstrains were isolated from Hospital of Sir Run Run Shaw of Zhejiang University ,thirteen from Wenzhou Hospital of Traditional Chinese Medicine ,one from Wenzhou People′s Hospital ,three from the First Affiliated Hospital of Wenzhou Medical University and three from Wenzhou Hospital of Integrated Traditional Chinese and Western Medicine .Thirty‐one strains were confirmed as carbapenemase‐producing with 24 of blaKPC‐2 ,3 of blaNDM‐1 ,1 of blaNDM‐5 and 3 of blaIMP‐4 .Among them ,one strain carried blaNDM‐1 with blaIMP‐4 and one strain carried blaNDM‐1with blaKPC‐2 ,respectively .The plasmid transfer and conjugation experiment was performed between strains carrying blaNDM‐1 and Escherichia coli EC600 or K . pneumoniae ATCC13833 and genes of blaNDM‐1 and ISAba125‐NDM were obtained .Conclusions blaKPC‐2 gene is the popular carbapenemase genotype .blaNDM‐1 or blaNDM‐5 may be correlated with linkage gene of ISAba125‐N DM .Coexistence of blaNDM‐1 carrying blaIMP‐4 or blaKPC‐2 is detected in the same strain , respectively . Enough importance should be attached to the strains ,because most of them are multiple drug resistance with related genes located in the plasmid which is easily spread between strains .

Objective To investigate the influence of experimental scotoma on multifocal visual evoked potential (mf-VEP). Methods The mf-VEP of 10 healthy individuals (20 eyes) was measured with VERIS Science 4.0. Every eye was measured for 3 times. The right eye was measured with full field stimulation and upper hemi-field or lower hemi-field masked. The left eye was measured with full field stimulation and central three-rings area or lower nasal field masked. The first slice responses of the second order in different field were analyzed and compared by VERIS software. Results The mf-VEP in masked area was undetectable or obviously decreased in all subjects. In most unmasked field, the amplitudes of mf-VEP were not changed, except that in some place decreased slightly with statistically significant difference in comparison to the full field stimulation mode. Conclusion mf-VEP is influenced with experimental scotoma. The mf-VEP changes are consistent with the visual field masked.