Hydrogen sulfide improves endothelial barrier function by modulating the ubiquitination degradation of KLF4 through TRAF7 S-sulfhydration in diabetic aorta.

Anomalous vascular endothelium significantly contributes to various cardiovascular diseases. VE-cadherin plays a vital role in governing the endothelial barrier. Krüppel-like factor 4(KLF4), as a transcription factor, which binds the VE-cadherin promoter and enhances its transcription. Tumor necrosis factor receptor-associated factor 7 (TRAF7) is an E3 ubiquitin ligase that has been shown to modulate the degradation of KLF4. H2S can covalently modify cysteine residues on proteins through S-sulfhydration, thereby influencing the structure and functionality of the target protein. However, the role of S-sulfhydration on endothelial barrier integrity remains to be comprehensively elucidated. This study aims to investigate whether protein S-sulfhydration in the endothelium regulates endothelial integrity and its underlying mechanism. In this study, we observed that protein S-sulfhydration was reduced in the endothelium during diabetes and TRAF7 was the main target. Overexpression of TRAF7-Cys327 mutant could mitigate the endothelial barrier damage by weakening TRAF7 interaction with KLF4 and reducing ubiquitination degradation of KLF4. In conclusion, our research demonstrates that H2S plays a pivotal role in regulating S-sulfhydration of TRAF7 at Cys327. This regulation effectively inhibits the ubiquitin-mediated degradation of KLF4, resulting in an upregulation of VE-cadherin levels. This molecular mechanism contributes to the prevention of endothelial barrier damage.

Identification and characterization of a novel 6'-N-aminoglycoside acetyltransferase AAC(6')-Va from a clinical isolate of Aeromonas hydrophila.

Background: Aeromonas species have been identified as agents responsible for various diseases in both humans and animals. Multidrug-resistant Aeromonas strains pose a significant public health threat due to their emergence and spread in clinical settings and the environment. The aim of this study was to determine a novel resistance mechanism against aminoglycoside antimicrobials in a clinical isolate. Methods: The function of aac(6')-Va was verified by gene cloning and antibiotic susceptibility tests. To explore the in vivo activity of the enzyme, recombinant proteins were expressed, and enzyme kinetics were tested. To determine the molecular background and mechanism of aac(6')-Va, whole-genome sequencing and bioinformatic analysis were performed. Results: The novel aminoglycoside N-acetyltransferase gene aac(6')-Va confers resistance to several aminoglycosides. Among the antimicrobials tested, ribostamycin showed the highest increase (128-fold) in the minimum inhibitory concentration (MIC) compared with the control strains. According to the MIC results of the cloned aac(6')-Va, AAC(6')-Va also showed the highest catalytic efficiency for ribostamycin [kcat/Km ratio = (3.35 ± 0.17) × 104 M-1 s-1]. Sharing the highest amino acid identity of 54.68% with AAC(6')-VaIc, the novel aminoglycoside N-acetyltransferase constituted a new branch of the AAC(6') family due to its different resistance profiles. The gene context of aac(6')-Va and its close relatives was conserved in the genomes of species of the genus Aeromonas. Conclusion: The novel resistance gene aac(6')-Va confers resistance to several aminoglycosides, especially ribostamycin. Our finding of a novel resistance gene in clinical A. hydrophila will help us develop more effective treatments for this pathogen's infections.

Identification and characterization of a novel ß-lactamase gene, blaAMZ-1, from Achromobacter mucicolens.

Background: Achromobacter is a genus of gram-negative bacteria that can act as opportunistic pathogens. Recent studies have revealed that some species of Achromobacter show inherent resistance to ß-lactams, but the resistance mechanisms of Achromobacter mucicolens have rarely been reported. Method: The bacterium was isolated using standard laboratory procedures. The agar dilution method was used to determine the minimum inhibitory concentrations (MICs). Genome sequencing was performed using the PacBio RS II and Illumina HiSeq 2500 platforms, and the Comprehensive Antibiotic Resistance Database (CARD) was used to annotate the drug resistance genes. The localization of the novel ß-lactamase AMZ-1 was determined, and its characteristics were determined via molecular cloning and enzyme kinetic analysis. The phylogenetic relationship and comparative genomic analysis of the resistance gene-related sequences were also analyzed. Result: Achromobacter mucicolens Y3, isolated from a goose on a farm in Wenzhou, showed resistance to multiple antibiotics, including penicillins and cephalosporins. BlaAMZ-1 showed resistance to amoxicillin, penicillin G, ampicillin, cephalothin and cefoxitin, and the resistance activity could be inhibited by ß-lactamase inhibitors. Enzyme kinetic analysis results showed that AMZ-1 has hydrolytic activity against a wide range of substrates, including cephalothin, amoxicillin, penicillin G, and cefoxitin but not ampicillin. The hydrolytic activity of AMZ-1 was greatly inhibited by avibactam but much more weakly inhibited by tazobactam. Mobile genetic elements could not be found around the blaAMZ-1-like genes, which are conserved on the chromosomes of bacteria of the genus Achromobacter. Conclusion: In this study, a novel AmpC gene, blaAMZ-1, from the animal-origin bacterium A. mucicolens Y3 was identified and characterized. It conferred resistance to some penicillins and first- and second-generation cephalosporins. The identification of this novel resistance gene will be beneficial for the selection of effective antimicrobials to treat associated infections.

Identification and characterization of a novel chromosomal aminoglycoside 3'-O-phosphotransferase, APH(3')-Id, from Kluyvera intermedia DW18 isolated from the sewage of an animal farm.

Background: Aminoglycosides, as important clinical antimicrobials, are used as second-line drugs for treating multidrug-resistant tuberculosis or combined with ß-lactam drugs for treating severe infections such as sepsis. Aminoglycoside-modifying enzyme (AME) is the most important mechanism of aminoglycoside resistance and deserves more attention. Methods: The bacterium Kluyvera intermedia DW18 was isolated from the sewage of an animal farm using the conventional method. The agar dilution method was used to determine the minimum inhibitory concentrations (MICs) of antimicrobials. A novel resistance gene was cloned, and the enzyme was expressed. The kinetic parameters were measured by a SpectraMax M5 multifunctional microplate reader. Bioinformatic analysis was performed to reveal the genetic context of the aph(3')-Id gene and its phylogenetic relationship with other AMEs. Results: A novel aminoglycoside 3'-O-phosphotransferase gene designated aph(3')-Id was identified in K. intermedia DW18 and shared the highest amino acid identity of 77.49% with the functionally characterized aminoglycoside 3'-O-phosphotransferase APH(3')-Ia. The recombinant plasmid carrying the novel resistance gene (pMD19-aph(3')-Id/E. coli DH5α) showed 1,024-, 512-, 128- and 16-fold increased MIC levels for kanamycin, ribostamycin, paromomycin and neomycin, respectively, compared with the reference strain DH5α. APH(3')-Id showed the highest catalytic efficiency for ribostamycin [kcat/Km of (4.96 ± 1.63) × 105 M-1/s-1], followed by paromomycin [kcat/Km of (2.18 ± 0.21) × 105 M-1/s-1], neomycin [kcat/Km of (1.73 ± 0.20) × 105 M-1/s-1], and kanamycin [kcat/Km of (1.10 ± 0.18) × 105 M-1/s-1]. Three conserved functional domains of the aminoglycoside phosphotransferase family and ten amino acid residues responsible for the phosphorylation of kanamycin were found in the amino acid sequence of APH(3')-Id. No mobile genetic element (MGE) was discovered surrounding the aph(3')-Id gene. Conclusion: In this work, a novel aminoglycoside 3'-O-phosphotransferase gene designated aph(3')-Id encoded in the chromosome of the environmental isolate Kluyvera intermedia DW18 was identified and characterized. These findings will help clinicians select effective antimicrobials to treat infections caused by pathogens with this kind of resistance gene.

BlaPSZ-1, a novel AmpC gene identified from a Pantoea isolate.

Background: Pantoea species of the family Erwiniaceae are well-known plant pathogens and animal and human conditional pathogens. Due to the widespread and continuous use of antimicrobials, multidrug-resistant strains continue to emerge, making clinical treatment difficult; therefore, there is an increasing need to clarify the mechanisms of drug resistance. Methods: A rabbit anal fecal sample was collected by a swab and the streak plate method was used to isolate single colonies. The standard agar dilution method was used to determine the minimum inhibitory concentrations (MICs) against antimicrobials. The complete genome sequence of the bacterium was obtained using Next-Generation Sequencing platforms. The potential resistance gene was annotated based on the Comprehensive Antibiotic Resistance Database (CARD) and verified by molecular cloning. The ß-lactamase PSZ-1 was expressed via the pCold I expression vector and its enzyme kinetic parameters were analyzed. The genetic environment and evolutionary process of the novel resistance gene-related sequences were analyzed by bioinformatic methods. Results: The isolate Pantoea endophytica X85 showed some degree of resistance to penicillins as well as cephalosporins. A novel AmpC resistance gene, designated blaPSZ-1 in this research, was identified to be encoded in the plasmid (pPEX85) of P. endophytica X85. BlaPSZ-1 showed resistance to penicillins and several first-, second-and third-generation cephalosporins as well as aztreonam, but it did not show resistance to the fourth-generation cephalosporins or carbapenems tested. Enzyme kinetic assays revealed that it could hydrolyze amoxicillin, penicillin G, cephalothin, and cefazolin, and its hydrolytic activity could be strongly inhibited by the inhibitor avibactam, which was generally consistent with antimicrobial susceptibility testing results. No hydrolytic activity was observed for third-generation cephalosporins or aztreonam. Conclusion: In this study, a novel AmpC ß-lactamase gene, designated blaPSZ-1, was characterized and it was encoded in the plasmid of the bacterium P. endophytica X85. It shows resistance to penicillins and several cephalosporins. The discovery of novel drug resistance mechanisms can help guide the scientific use of drugs in animal husbandry and clinical practice, effectively avoiding the abuse of antimicrobials and thus preventing the further development and spread of bacterial resistance.

Factors associated with poorer childbirth outcomes in pregnant women diagnosed with placenta previa.

OBJECTIVE: Placenta previa is a health issue during pregnancy when the placenta wholly or partially covers the opening of the uterus. It can result in bleeding during pregnancy or after delivery, and preterm delivery. This study aimed to investigate the risk factors correlated with poorer childbirth outcomes of placenta previa. MATERIALS AND METHODS: Between May 2019 and January 2021, pregnant women diagnosed with placenta previa in our hospital were enrolled. Outcomes were postpartum hemorrhage after childbirth, and lower Apgar score and preterm delivery of the neonate. Laboratory blood examination data preoperatively were collected from medical records. RESULTS: A total of 131 subjects were included, with a median age 31 years. Multivariate analysis showed that fibrinogen reduced risk for postpartum hemorrhage (adjusted odds ratio (aOR): 0.45, 95% confidence interval (CI): 0.26-0.79, p = 0.005). Homocysteine (aOR: 0.73, 95% CI: 0.54-0.99, p = 0.04) reduced the risk while D-dimer (aOR: 1.19, 95% CI: 1.02-1.37, p = 0.02) increased the risk for low Apgar score. Age (aOR: 0.86, 95% CI: 0.77-0.96, p = 0.005) decreased the risk but history of full-term pregnancy more than twice (aOR: 8.58, 95% CI: 2.32-31.71, p = 0.001) increased the risk for preterm delivery. CONCLUSION: The findings suggest that poorer childbirth outcomes in pregnant women with placenta previa are associated with young age, history of full-term pregnancy, and preoperative concentrations of low fibrinogen, low homocysteine and high D-dimer. This provides obstetricians adjunctive information for early screening of high-risk population and relevant treatment arrangement in advance.

[Expression of SIL-2R in Patients with Multiple Myeloma and Its Clinical Significance].

OBJECTIVE: To investigate the expression and clinical significance of soluble interleukin-2 receptor(sIL-2R) in patients with multiple myeloma(MM). METHODS: 54 newly diagnosed MM patients in the Second Affiliated Hospital of Fujian Medical University from February 2020 to December 2021 were selected as the observation group, and 60 healthy people in our hospital in the same period were selected as the control group. The expression levels of sIL-2R in the serum of the two groups were detected by enzyme-linked immunosorbent assay. The differences of sIL-2R expression level among different clinical parameter groups in MM patients were compared. The clinical parameters include:gender, age, ISS stage, hemoglobin, albumin, serum creatinine, lactate dehydrogenase and ß2-microglobulin, blood calcium, bone marrow plasma cell ratio and treatment response. The relationship between sIL-2R expression level and progression-free survival(PFS) and overall survival(OS) in MM patients were analyzed. RESULTS: The expression of serum SIL-2R in MM patients was significantly higher than that in healthy control group (P<0.05). The expression of sIL-2R in MM patients who did not achieve complete remission(CR) was significantly higher than those of CR patients (P=0.037). There was no significant difference in the expression of serum sIL-2R between the groups of different sex, age, ISS stage, hemoglobin concentration, albumin content, serum creatinine level, lactate dehydrogenase level, the content of ß2-microglobulin, the concentration of blood calcium, and the proportion of bone marrow plasma cells(P>0.05). The PFS of sIL-2R high expression group(15 months) was shorter than that of sIL-2R low expression group (22 months), which was significant difference (P=0.041). But there was no significant difference in OS between sIL-2R high expression group and sIL-2R low expression group (P=0.124). Univariate analysis results showed that the high expression of serum sIL-2R was associated with poor PFS in MM patients. Multivariate analysis results showed that the high expression of serum sIL-2R was still an independent adverse prognostic factor for PFS in MM patients, However, the expression of serum sIL-2R was not statistically significant in evaluating OS in MM patients by univariate and multivariate analysis. CONCLUSION: The expression of serum sIL-2R in MM patients was significantly higher than that in healthy people. Serum sIL-2R is an independent prognostic factor of PFS in MM patients.

Characterization and Identification of a novel chromosome-encoded metallo-ß-lactamase WUS-1 in Myroides albus P34.

In this study, we identified and characterized a novel chromosomally-encoded class B metallo-ß-lactamase (MBL) gene designated bla WUS-1 in a carbapenem-resistant isolate Myroides albus P34 isolated from sewage discharged from an animal farm. Comparative analysis of the deduced amino acid sequence revealed that WUS-1 shares the highest amino acid similarities with the function-characterized MBLs MUS-1 (AAN63647.1; 70.73%) and TUS-1 (AAN63648.1; 70.32%). The recombinant carrying bla WUS-1 exhibited increased MICs levels against a number of ß-lactam antimicrobials such as carbenicillin, ampicillin and imipenem, and ß-lactamase inhibitors (clavulanic acid and tazobactam). The metallo-ß-lactamase WUS-1 could also hydrolyze these antimicrobials and the hydrolytic activities could be inhibited by EDTA. Genetic context analysis of bla WUS-1 revealed that no mobile genetic element was found in its surrounding region. The plasmid pMA84474 of Myroides albus P34 harbored 6 resistance genes (bla OXA-347, aadS, bla MYO-1, ereD, sul2 and ermF) within an approximately 17 kb multidrug resistance (MDR) region. These genes, however, were all related to mobile genetic elements.

AadA36, a novel chromosomal aminoglycoside nucleotidyltransferase from a clinical isolate of Providencia stuartii.

In this study, we characterized a novel chromosome-encoded aminoglycoside nucleotidyltransferase (ANT), AadA36, from the Providencia stuartii strain P14 isolated from the sputum specimen of a burn patient at a hospital in Wenzhou, China. Among the functionally characterized ANTs, AadA36 shared the highest amino acid sequence identity of 51.91% with AadA14. The whole genome of P. stuartii P14 consisted of one chromosome and two plasmids (designated pP14-166 and pP14-114). A total of 19 genes with ≥80% similarity with functionally characterized antimicrobial resistance genes (ARGs) were identified in the whole genome, including aminoglycosides [aac(2')-Ia, aph(6)-Id, aph(3″)-Ib, aac(6')-Ib, ant(3″)-IIa, aph(3')-Ia], ß-lactams (bla CMY-2 and bla OXA-10) and so on. Antimicrobial susceptibility testing showed that the aadA36 gene conferred specific resistance to spectinomycin and streptomycin, and the minimum inhibitory concentration (MIC) of these antimicrobials increased 128- and 64-fold compared with the control strain. The kinetic parameters of AadA36 were consistent with the MIC data of spectinomycin and streptomycin, with kcat /Km ratios of (1.07 ± 2.23) × 104 M-1 s-1 and (8.96 ± 1.01) × 103 M-1 s-1, respectively. The identification of a novel aminoglycoside resistance gene will help us further understand the complexity of the resistance mechanisms and provide deep insights into the dissemination of resistance genes in the microbial population.

Identification of a novel aminoglycoside O-nucleotidyltransferase AadA33 in Providencia vermicola.

A novel chromosome-encoded aminoglycoside O-nucleotidyltransferase AadA33 was identified in Providencia vermicola strain P13. The AadA33 shares the highest amino acid identity of 51.28% with the function characterized AadA31. Antibiotic susceptibility testing and enzyme kinetics analysis revealed that the function of AadA33 is to mediate spectinomycin and streptomycin resistance. The recombinant strain harboring aadA33 (pUCP20-aadA33/Escherichia coli DH5α) displayed >256- and 128-fold increases in the minimum inhibitory concentration levels to spectinomycin and streptomycin, respectively, compared with the control strains pUCP20/DH5α. Enzyme kinetic parameters manifested the substrate of AadA33 including spectinomycin and streptomycin, with k cat/K m of 3.28 × 104 (M-1 s-1) and 3.37 × 104 (M-1 s-1), respectively. Bioinformatics analysis revealed its structural mechanism of antimicrobial resistance, genetic context, and phylogenetic relationship with other aminoglycoside O-nucleotidyltransferases. This study of AadA33 contributed to understanding the function and resistance mechanism of aminoglycoside O-nucleotidyltransferase.

A Corrective Method for Different Hematocrit Values of Whole Blood Samples on the Detection of Procalcitonin.

BACKGROUND: We have explored that quantitative PCT detection can be conducted in different sample types (whole blood and/or plasma samples) with good correlation and consistency in clinical use. These findings reduce the sample volume and turnover time of PCT detection in clinical labs. However, different hematocrit (HCT) percentages of whole blood samples may affect the final results, especially abnormal hematocrit (HCT) percentages. To overcome this problem, we established a mathematical model to modify the whole blood test results and evaluated the effects of HCT correction. METHODS: First, we prepared a preliminary experiment - various hematocrit (HCT) percentages (15% - 65%) of whole blood samples with different PCT concentrations and established a mathematic model to correct the effects of PCT detection. Then, in this paper, we evaluated the consistency with Pearson's correlation and Kappa analysis between whole bloods detected by the i-Reader S system and plasma detected by the Biomerieux system. Besides, we prepared different HCT values about 15%, 40%, 60% of 9 samples with different PCT concentrations to evaluate the effects of HCT correction Results and Conclusions: Pearson's correlative studies and Kappa analysis indicated that PCT levels measured by i-Reader S (plasma & whole blood samples) were comparable to results from the VIDAS system, and HCT correction could improve consistency of PCT detection between whole blood and plasma. Analysis of samples with abnormal HCT values showed that the mathematical correction model could offset the influences of various HCT values.

[Serum Lipid Levels and Their Prognostic Significance in Patients with Multiple Myeloma].

OBJECTIVE: To investigate the serum lipid levels and their prognostic significance in patients with multiple myeloma (MM). METHODS: A total of 87 newly diagnosed MM patients and 87 healthy controls in our hospital from January 2012 to April 2021 were selected. Serum lipid levels were compared between MM patients and healthy controls. The differences of serum lipid levels in patients among two groups of sex, age, hemoglobin (Hb), albumin (ALB), platelet (PLT), ß2-microglobulin (ß2-MG) and bone marrow plasma cell ratio (BMPC), different immune types, different ISS stages, before and after chemotherapy were analyzed. Univariate and COX multivariate regression analysis were used to analyze the influence of clinical parameters such as serum lipid indexes on prognosis of MM. RESULTS: The serum levels of total cholesterol (TC), low density lipoprotein cholesterol (LDL-C), high density lipoprotein cholesterol (HDL-C), apolipoprotein A1 (Apo A1) and apolipoprotein B (Apo B) in MM patients were significantly lower than those in healthy controls (P<0.05). Anemia, low protein and low PLT in patients were related to low cholesterol. The levels of TC, LDL-C, HDL-C, Apo A1 and Apo B in patients with low Hb and ALB were significantly lower than those in patients with high Hb and ALB (P<0.05). The Apo B level of low PLT patients was significantly lower than that of high PLT patients (P<0.05). The levels of TC, LDL-C, HDL-C, Apo A1 and Apo B in patients with different immune types were significantly different, the above indexes of IgA type were significantly lower than IgG type(P<0.05), IgG type were significantly lower than light chain type(P<0.05), double clone type were significantly lower than light chain type (P<0.05). The levels of TC, LDL-C, and Apo B in patients with different ISS stages were significantly different, stage Ⅱ were lower than those of stage Ⅰ (P>0.05), stage Ⅲ were significantly lower than those of stage Ⅱ and stageⅠ(P<0.05). The levels of TC, TG, LDL-C, HDL-C, Apo A1 and Apo B in patients after chemotherapy were significantly higher than those before chemotherapy (P<0.05). Univariate analysis showed that Hb, PLT, ß2-MG, BMPC, LDL-C and Apo B affected the prognosis of MM. Multivariate analysis showed that BMPC and Apo B were independent factors affecting the prognosis of MM. CONCLUSION: The serum cholesterol level is decreased in MM patients, and hypocholesterolemia is related to the classification and staging of the disease. With the improvement of the disease, the serum cholesterol level is increased, and low serum Apo B level predicts a poor prognosis.

Mode of action of nanochitin whisker against Fusarium pseudograminearum.

Nanochitin whisker (NC) is an advanced nanobiomaterial with novel physicochemical and biological properties. Fusarium pseudograminearum (Fpg) is an important pathogenic fungus causing wheat crown rot disease. This study explored the mode of action of NC against Fpg as a target microorganism. The effects of different treatments and concentrations of NC on the fungal growth and conidial germination were investigated by in vitro bioassay. The impacts of NC on cell structure integrity, membrane permeability, pathogenesis related key enzymes activity, and the mycotoxin production were examined by electron microscopy, fluorescence spectroscopy, IR spectroscopy, conductometry, and spectrophotometry, respectively. The results showed that NC significantly reduced hyphal growth, and the spore germination rate of Fpg declined by 33.0 % and 23.2 % when Fpg was treated with 30 and 300 µg/mL of NC, respectively. NC vigorously influenced structural stability of cell wall by destroying dextran structure, and strongly stimulated ergosterol production altering membrane integrity of the fungus. It reduced the activities of enzymes related to energy-supply like nicotinamide adenine dinucleotide oxidase and succinate dehydrogenase remarkably. The production of fungal mycotoxin deoxynivalenol was also decreased by NC. These findings provide an important basis for fully understanding the mechanism of nanobiomaterial in plant fungal disease control.

Early predictors of lung necrosis severity in children with community-acquired necrotizing pneumonia.

OBJECTIVE: To analyze baseline clinical and laboratory characteristics and explore the possible predictors of lung necrosis severity in children with community-acquired necrotizing pneumonia (NP). METHODOLOGY: This retrospective observational study was performed in a tertiary referral center. A total of 104 patients aged <15 years with community-acquired pneumonia and radiologically confirmed NP by computed tomography (CT) were included. Patients were classified into the mild, moderate, or massive necrosis groups. RESULTS: Among them, 29, 41, and 34 patients had mild, moderate, and massive necrosis, respectively. Moreover, 34.6% of the patients were admitted to pediatric intensive care unit. Massive necrosis was more likely to occur during winter (p < 0.05) and was associated with more severe clinical outcomes, such as longer duration of fever, longer hospitalization, increased mortality, and a higher risk of subsequent surgical intervention (p < 0.05). Multivariate analysis demonstrated that the following were independent risk factors for massive necrosis in this study: C-reactive protein (CRP) (p = 0.036), serum albumin (p = 0.009), and immunoglobulin M (IgM) (p = 0.022). Receiver operating characteristic analysis showed that when the cut-off value for CRP, serum albumin, and IgM were set at 122 mg/L, 30.8 g/L, and 95.7 mg/dl, respectively, they showed good diagnostic performance for differentiating patients with massive necrosis from all patients with NP. CONCLUSION: NP is a potentially severe complication of pediatric community-acquired pneumonia. Different severities of lung necrosis can lead to different clinical outcomes. CRP, serum albumin, and IgM levels are independent predictors of the degree of lung necrosis.

Colistin Resistance and Molecular Characterization of the Genomes of mcr-1-Positive Escherichia coli Clinical Isolates.

Research on resistance against polymyxins induced by the mcr-1 gene is gaining interest. In this study, using agar dilution method, polymerase chain reaction, and comparative genomic analysis, we investigated the colistin resistance mechanism of clinical E. coli isolates. The minimum inhibitory concentration (MIC) analysis results revealed that of the 515 isolates tested, bacteria with significantly increased MIC levels against colistin were isolated in 2019. Approximately one-fifth (17.14% to 19.65%) of the isolates showed MIC values ≥1 mg/L against colistin in 2015, 2016, and 2017. However, in 2019, up to three-quarters (74.11%, 146/197) of the isolates showed MIC values ≥1 mg/L against colistin indicating an increase in colistin resistance. Six isolates (EC7518, EC4968, EC3769, EC16, EC117, EC195, 1.13%, 6/515) were found to carry the mcr-1 gene and a novel mcr-1 variant with Met2Ile mutation was identified in EC3769. All six strains showed higher MIC levels (MIC=4 mg/L) than any mcr-1-negative strains (MIC ≤ 2 mg/L). Whole-genome sequencing of the six mcr-1-positive isolates revealed that EC195 carried the highest number of resistance genes (n = 28), nearly a half more than those of the following EC117 (n = 19). Thus, EC195 showed a wider resistance spectrum and higher MIC levels against the antimicrobials tested than the other five isolates. Multi-locus sequence typing demonstrated that these mcr-1-positive strains belonged to six different sequence types. The six mcr-1 genes were located in three different incompatibility group plasmids (IncI2, IncHI2 and IncX4). The genetic context of mcr-1 was related to a sequence derived from Tn6330 (ISApl1-mcr-1-pap2-ISApl1). Investigations into the colistin resistance mechanism and characterization of the molecular background of the mcr genes may help trace the development and spread of colistin resistance in clinical settings.

Molecular Mechanism of the ß-Lactamase Mediated ß-Lactam Antibiotic Resistance of Pseudomonas aeruginosa Isolated From a Chinese Teaching Hospital.

Pseudomonas aeruginosa can cause infections in the blood, lungs (pneumonia), or other parts of the body after surgery. To investigate the molecular characteristics of ß-lactam antibiotic resistance of P. aeruginosa isolated from a hospital population between 2015 and 2017, in this study, the antimicrobial susceptibility and the resistance gene profile of the bacteria were determined. The Pulsed-field gel electrophoresis (PFGE) was used to characterize the clonal relatedness and sequencing and comparative genomic analysis were performed to analyze the structure of the resistance gene-related sequences. As a result, of the 260 P. aeruginosa strains analyzed, the resistance rates for 6 ß-lactam antibiotics ranged from 4.6 to 9.6%. A total of 7 genotypes of 44 ß-lactamase genes were identified in 23 isolates (8.9%, 23/260). Four transconjugants from different donors carrying bla CARB-3 exhibited a phenotype of reduced susceptibility to piperacillin-tazobactam, ceftazidime, and cefepime, and 2 transconjugants harboring bla IMP-45 exhibited a phenotype of reduced susceptibility to carbapenems. bla CARB positive isolates (n = 12) presented six PFGE patterns, designated groups A to F. Two bla genes (bla IMP-45 and bla OXA-1) in PA1609 related to a class 1 integron (intI1-bla IMP-45- bla OXA-1-aac(6')-Ib7-catB3-qacE∆1-sul1) were encoded on a plasmid (pPA1609-475), while the bla CARB-3 gene of PA1616 also related to a class 1 integron was located on the chromosome. The results suggest that ß-lactam antibiotic resistance and clonal dissemination exist in this hospital population. It indicates the necessity for molecular surveillance in tracking ß-lactamase-producing strains and emphasizes the need for epidemiological monitoring.

[Clinical Analysis of Acute Myeloid Leukemia Patients with Hemophagocytic Syndrome].

OBJECTIVE: To investigate the clinical features of acute myeloid leukemia patients with hemophagocytic syndrome. METHODS: The clinical data of 2 patients with acute myeloid leukemia complicated with hemophagocytic syndrome were collected, and the clinical characteristics and treatment outcomes were analyzed. RESULTS: There were two patients with acute myeloid leukemia, including 1 male and 1 female，aged for 67 and 40 years old，respectively. Hemophagocytic syndrome occurred in one patient after induction therapy for acute myeloid leukemia and one patient after consolidation therapy. Both of the patients with hemophagocytic syndrome showed fever, hemocytopenia, high ferritin, high titer sCD25 levels and hemophagocytes in bone marrow. After achieved anti-infection, glucocorticoid, human immunoglobulin and etoposide regimens treatment, hemophagocytic syndrome was controlled in both of the two patients. One patient failed to induce acute myeloid leukemia and one patient achieved complete remission. CONCLUSION: Acute myeloid leukemia complicated with hemophagocytic syndrome is rare. Early identification, early anti-infection combined with HLH94 regimen can control hemophagocytosis and improve prognosis.

The Effects of Different Blood Sample Types on Quantitative Detection of Procalcitonin.

BACKGROUND: Procalcitonin (PCT) has been recommended and widely used for the prognosis, diagnosis, and monitoring of sepsis. Currently, a majority of PCT detection products are limited to using serum samples, which requires the tedious pre-treatment process, as well as a large sample volume for analysis. Hence, there is an increasing need to replace serum with plasma or whole blood samples. In this work, we evaluated the effects of different blood sample types on PCT quantitative detection by measuring PCT levels in clinically homogenous whole blood, plasma, and serum samples, in hope of extending the application of PCT detection in more sample types. METHODS: Ninety patients from Tong Ren Hospital of Shanghai Jiao Tong University, School of Medicine with different PCT levels volunteered for this study. Clinically homogenous samples, including EDTA- K2 anticoagulant whole blood, centrifuged serum and procoagulant plasma, were collected and analyzed using i-Reader S automatic immunoanalyzer and its supporting reagent kits. Passing and Bablok regression analysis, Bland-Altman plotting, and Kappa test were used for consistency analysis and the determination of consistency intensity, respectively. RESULTS: Correlation analysis showed that PCT concentrations measured from EDTA-K2 anticoagulated plasma samples had a good linear regression relationship with PCT from serum samples, with a slope of 0.8741, r = 0.958, p < 0.05. A similar correlation was observed between whole blood and serum, with a slope of 0.9234, r = 0.965, p < 0.05. A good correlation was found from the quantitative results of different sample types obtained from the same patient. In detail, PCT levels in EDTA-K2 anticoagulant whole blood and plasma are well correlated with that in the serum (r = 0.831, p < 0.05; r = 0.814, p < 0.05). There was no significant difference among different sample types (p > 0.05). Variation in PCT quantification induced by different sample types has no statistical influence on positive/negative decision (p > 0.05). Bland-Altman analysis for assessing PCT concentration agreement showed there was no outlier ratio between whole blood and plasma within the range of the detection system, as well as no outlier between serum and plasma. Kappa coefficient of PCT concentration between serum and homologous EDTA-K2 anticoagulated plasma was 0.8942 (p < 0.001), and for serum and homologous whole blood it was 0.6954 (p < 0.001). CONCLUSIONS: We concluded that quantitative PCT detection can be conducted in different sample types with good correlation and consistency, which means that it is feasible to replace serum samples with whole blood and/or plasma samples for PCT detection in clinical use. These findings reduce the sample volume and turnover time of PCT detection in clinical labs, greatly improving the process of PCT detection and promoting the application of PCT as an important inflammatory biomarker for disease diagnosis.