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Objective@#To retrospectively analyze the diagnosis time, pathogen distribution, and drug resistance of fungal bloodstream infection in severe burn patients.@*Methods@#Blood samples were collected from 55 severe burn patients with fungal bloodstream infection (including 46 males and 9 females, aged 42 (1, 78) years) admitted to the intensive care unit of the Institute of Burn Research of the First Affiliated Hospital of Army Medical University (the Third Military Medical University) from July 2011 to May 2019 for retrospective analysis. Microbial monitoring system was used to cultivate pathogens, API yeast identification kit and Candida chromogenic medium were used to identify pathogens, and Kirby-Bauer paper disk diffusion method was used to detect drug resistance of fungi to fluconazole, amphotericin B, itraconazole, ketoconazole, and voriconazole. The positive rate of blood fungal culture, mortality rate, distribution of local fungal proliferation sites, the diagnosis time distribution of fungal bloodstream infection, the distribution of fungal species, resistance to commonly-used antifungal drugs, and the use of antibiotics were assessed. The WHONET 5.6 software was applied to analyze the distribution and drug resistance of fungi.@*Results@#(1) Totally 4 839 blood samples were collected during the 9 years, and 122 strains of fungi were isolated, with positive rate of 2.52%. The mortality rate was 14.55% (8 patients) in 55 patients. Catheter fungal proliferation ranked the first among 30 cases of local fungal proliferation. (2) The diagnosis time of fungal bloodstream infection mainly distributed in ≤1 week of hospitalization [32.73% (18/55)]. (3) Among the 55 strains of fungi detected, the detection rate of Candida parapsilosis ranked the first (21.82%, 12 strains), Candida glabrata was the second (18.18%, 10 strains), and Candida tropicalis was tied with Candida albicans in the third place (14.55%, 8 strains). All the detected fungi were sensitive to amphotericin B, and the resistance rates to voriconazole, fluconazole, itraconazole, and ketoconazole were between 4.5% and 9.1%. (4) Droad-spectrum antibiotics were used in all the 55 patients, ≥3 kinds of antibiotics were used in 44 patients, and 37 patients used antibacterial drugs ≥7 days.@*Conclusions@#The diagnosis time of fungal bloodstream infection in the 55 severe burn patients was mainly within 1 week of hospitalization. Candida parapsilosis is the most commonly detected fungal species. Catheter fungal proliferation occurs most commonly among the 30 patients with local fungal proliferation. All the detected fungi were sensitive to amphotericin B, with low drug resistance to voriconazole, fluconazole, itraconazole, and ketoconazole. Broad-spectrum antibiotics were overused in the severe burn patients with fungal bloodstream infection.
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Objective@#To analyze the distribution and drug resistance of pathogens isolated from patients with catheter-related bloodstream infection (CRBSI) in burn intensive care unit (BICU).@*Methods@#From January 2011 to December 2018, among 2 264 patients who were peripherally inserted central venous catheter at the BICU of the First Affiliated Hospital of Army Medical University (the third Military Medical University), hereinafter referred to as the author′s unit, 159 patients were diagnosed CRBSI, including 131 males and 28 females, aged 43 (1, 79) years. The pathogens primarily isolated from peripheral venous blood and central venous catheter blood/anterior central venous catheter specimen of patients with CRBSI were retrospectively analyzed. API bacteria identification kits and automatic microorganism identification instrument were used to identify pathogens. Broth micro-dilution method or Kirby-Bauer paper disk diffusion method was used to detect the drug resistance of the pathogens to 5 antifungal drugs including fluconazole and itraconazole, etc., and 37 antibacterial drugs including tigecycline and imipenem, etc. Modified Hodge test was used to further identify imipenem- and meropenem-resistant Klebsiella pneumonia. D test was used to detect erythromycin-induced clindamycin resistant Staphylococcus aureus. The WHONET 5.6 software was applied to analyze the annual incidence of CRBSI, mortality of patients with CRBSI, incidence of CRBSI cases, distribution of infection site, and duration of catheterization, detection of Gram-negative and Gram-positive bacteria, fungi, methicillin-resistant Staphylococcus aureus (MRSA), and methicillin-sensitive Staphylococcus aureus (MSSA), and drug resistance of fungi and major Gram-negative and Gram-positive bacteria to the commonly used antibiotics in clinic.@*Results@#(1) The incidence of CRBSI was 7.0% (159/2 264) during the eight years, which was slightly higher in 2014 and 2017 with 13.6% (30/221) and 11.1% (24/217) respectively. The mortality rate of patients with CRBSI was 7.5% (12/159). (2) The incidence of CRBSI cases was 14.9% (338/2 264); the main infection site was femoral vein, totally 271 cases (80.2%), and the duration of catheterization of this site was 9 (2, 25) d. (3) During the eight years, totally 543 strains of pathogens were isolated, including 353 (65.0%) strains of Gram-negative bacteria, 140 (25.8%) strains of Gram-positive bacteria, and 50 (9.2%) strains of fungi. The top three isolated pathogens with isolation rate from high to low were Acinetobacter baumannii, Staphylococcus aureus, and Pseudomonas aeruginosa, accounting for 23.2% (126/543), 17.1% (93/543), and 15.7% (85/543), respectively. Fungi were mainly Candida parapsilosis. Among the Staphylococcus aureus, the detection rate of MRSA was 98.9% (92/93), and that of MSSA was 1.1% (1/93). (4) Except for the low drug resistance rates to polymyxin B, minocycline, and tigecycline, the drug resistance rates of Acinetobacter baumannii to the other antibiotics were considerably high (80.1%-100.0%). Pseudomonas aeruginosa was not resistant to polymyxin B but highly resistant to netilmicin (88.7%) and piperacillin (92.6%), with resistance rates to the other antibiotics from 34.5% to 62.7%. Klebsiella pneumoniae was not resistant to tigecycline and lowly resistant to imipenem and meropenem (28.9%, 9 imipenem- and meropenem-resistant strains were further confirmed by modified Hodge test), with resistance rates to the other antibiotics from 40.9% to 95.2%. The resistance rates of MRSA to most antibiotics were higher than those of MSSA. MRSA was not resistant to linezolid, vancomycin, teicoplanin, sulfamethoxazole, or tigecycline. The resistance rates of MRSA to clindamycin and erythromycin were 7.9% and 62.0%, respectively, and those to the other antibiotics were higher than 91.5%. Except for the complete resistance to penicillin G and tetracycline, MSSA was not resistant to the other antibiotics. Thirty-three strains of Staphylococcus aureus showed resistance to erythromycin-induced clindamycin. Fungi was not resistant to amphotericin B, with drug resistance rates to voriconazole, itraconazole, ketoconazole, and fluconazole from 4.2% to 6.2%.@*Conclusions@#The incidence of CRBSI and mortality of patients with CRBSI are high in BICU of the author′s unit, and the main infection site is femoral vein. There are various types of pathogens in patients with CRBSI, and most of them are Gram-negative. The top three isolated pathogens are Acinetobacter baumannii, Staphylococcus aureus, and Pseudomonas aeruginosa, accompanying with grim drug resistance phenomenon.
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Objective@#To explore the resistance mechanism and gene type of carbapenems-resistant Klebsiella pneumoniae (CRKP) in burn care unit.@*Methods@#A total of 27 CRKP strains were primarily isolated from 22 patients [20 males, 2 females, aged (42±16) years] admitted to burn care unit of Institute of Burn Research of the First Affiliated Hospital of Army Medical University (the Third Military Medical University, hereinafter referred to as our department) from January to December 2017. After identification of bacteria, the months of detection and distribution of sample source were analyzed. Drug resistance tests of 15 antibiotics were conducted. Polymerase chain reaction was used to detect the drug resistant genes. Pulsed-field gel electrophoresis (PFGE) and multi-locus sequence typing (MLST) were used to analyze the gene type of strains.@*Results@#(1) During the whole year of 2017, CRKP strains were mostly detected in August (8 strains), September (6 strains), and October (5 strains), with no CRKP in January, March, June, November, and December. Five strains from bed units were detected in August (2 strains), September (1 strain), and October (2 strains). (2) Twenty-seven CRKP strains were derived from blood samples (40.7%, 11/27), wound exudate samples (18.5%, 5/27), deep vein catheter samples (11.1%, 3/27), sputum samples (7.4%, 2/27), urine samples (3.7%, 1/27), and bed unit samples (18.5%, 5/27). (3) The 27 CRKP strains were detected with drug-resistance rates of 100.0% to 7 antibiotics including cefoperazone/sulbactam, piperacillin/tazobactam, cefazolin, ceftriaxone, cefepime, ertapenem, and compound sulfamethoxazole, no drug-resistance to tigecycline, with drug-resistance rates higher than 81.0% to the rest 7 antibiotics. (4) Detection rates for resistance gene blaCTX-M-10, blaSHV, blaTEM, blaCTX-M-14, blaACT, and blaKPC were all above 92.5%. (5) According to PFGE, the 27 CRKP strains had 6 types (A, A1, A2, B, C, and D). Strains of type A were mainly detected in February, May, and September, with detection rate of 37.0% (10/27). Strains of type C were mainly detected in July, August, and October, with detection rate of 48.1% (13/27). Strains of types A1, A2, B, and D were scatteredly detected, with detection rate of 3.7% (1/27) respectively. According to MLST, the 27 CRKP strains had 6 STs. ST11 was the most frequent type, accounting for 74.1% (20/27), which was detected in August to October. The detection rate of ST395, ST2230, ST215, ST260, and STnew ranged from 3.7%(1/27) to 7.4%(2/27), and the strains were scatteredly detected.@*Conclusions@#The main source of CRKP from burn care unit of our department was bloodstream. All the CRKP strains showed high drug-resistance rate and complicated resistance mechanism. There were small scale outbreaks caused by CRKP of type A, type C, and ST11, which should be paid more attention to in clinical treatment and infection control.
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Objective@#To explore the effects of vitamin D3 on intestinal mucosal barrier of mice with severe burns.@*Methods@#Forty-two C57BL/6C male mice aged eight to twelve weeks were divided into vitamin D3 vehicle+ sham injury group of seven mice, vitamin D3 vehicle+ burn injury group of fourteen mice, vitamin D3+ sham injury group of seven mice, and vitamin D3+ burn injury group of fourteen mice according to random number table. Mice in vitamin D3 vehicle+ sham injury group and vitamin D3 vehicle+ burn injury group were injected with vehicle of vitamin D3 at a dose of 0.1 mL intraperitoneally at 1, 24, and 48 h before burn experiment. Mice in vitamin D3+ sham injury group and vitamin D3+ burn injury group were injected with vitamin D3 at a dose of 100 ng/kg dissolved in 0.1 mL vehicle intraperitoneally at the same time points. Mice in vitamin D3 vehicle+ burn injury group and vitamin D3+ burn injury group were inflicted with 30% total body surface area full-thickness dermal scald (hereinafter referred to as burn) on the back by 98 ℃ hot water for 3 to 4 seconds. And mice in vitamin D3 vehicle+ sham injury group and vitamin D3+ sham injury were treated with 37 ℃ water on the back for 3 to 4 seconds to simulate injury. Seven mice in vitamin D3 vehicle+ sham injury group and seven mice in vitamin D3+ sham injury group at post injury hour (PIH) 24, and seven mice in vitamin D3 vehicle+ burn injury group and seven mice in vitamin D3+ burn injury group at PIH 6 and 24 were sacrificed respectively to collect mesentery lymph nodes, spleens, livers, and intestinal tissue. The mesentery lymph nodes, spleens, and livers of mice in each group were collected to observe growth of bacteria, and number of bacteria was counted. Intestinal tissue of mice in each group was collected to detect protein expressions of zonal occludin 1 (ZO-1) and occludin by immunohistochemistry staining method, distribution of ZO-1 by immunofluorescence staining method, and expression of occludin by Western blotting. Data were processed with Kruskal-Wallis H test, Nemenyi test, one-way analysis of variance, t test, and Bonferroni correction.@*Results@#(1) At PIH 6 and 24, bacterial counts of mesentery lymph nodes, livers, and spleens of mice in vitamin D3 vehicle+ burn injury group were significantly higher than those of mice in vitamin D3 vehicle+ sham injury group (P<0.05). At PIH 6, bacterial counts of livers and spleens of mice in vitamin D3+ burn injury group were significantly lower than those of mice in vitamin D3 vehicle+ burn injury group (P<0.05). At PIH 24, bacterial counts of mesentery lymph nodes and livers of mice in vitamin D3+ burn injury group were significantly lower than those of mice in vitamin D3 vehicle+ burn injury group (P<0.05). (2) At PIH 6 and 24, expressions of ZO-1 and occludin of intestinal tissue of mice in vitamin D3 vehicle+ burn injury group were significantly lower than those of mice in vitamin D3 vehicle+ sham injury group, and expressions of ZO-1 and occludin of intestinal tissue of mice in vitamin D3+ burn injury group were close to those of mice in vitamin D3+ sham injury group. At PIH 6 and 24, expressions of ZO-1 and occludin of intestinal tissue of mice in vitamin D3+ burn injury group were significantly higher than those of mice in vitamin D3 vehicle+ burn injury group. (3) At PIH 6 and 24, compared with that of mice in vitamin D3 vehicle+ sham injury group, distribution of ZO-1 of intestinal mucosal epithelium of mice in vitamin D3 vehicle+ burn injury group was discontinuous. Distribution of ZO-1 of intestinal mucosal epithelium of mice in vitamin D3+ sham injury group was normal, and the distribution of ZO-1 of intestinal mucosal epithelium of mice in vitamin D3+ burn injury group was with good continuity. (4) At PIH 6 and 24, expressions of occludin of intestinal tissue of mice in vitamin D3 vehicle+ burn injury group were 0.720±0.003, 0.638±0.052 respectively, significantly lower than 0.918±0.003 of mice in vitamin D3 vehicle+ sham injury group (t=57.33, 5.36, P<0.05). At PIH 6 and 24, expressions of occludin of intestinal tissue of mice in vitamin D3+ burn injury group were 0.994±0.058, 1.064±0.060, close to 0.938±0.023 of mice in vitamin D3+ sham injury group (t=0.91, 1.96, P>0.05). At PIH 6 and 24, expressions of occludin of intestinal tissue of mice in vitamin D3 vehicle+ burn injury group were significantly lower than those of mice in vitamin D3+ burn injury group (t=4.75, 5.35, P<0.05).@*Conclusions@#Intestinal bacterial translocation can occur in the early stage of severe burn. And vitamin D3 plays a protective role in the intestinal mucosal barrier post severe burn to reduce the bacterial translocation by protecting tight junction proteins of intestinal epithelium.
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Objective To investigate the trans‐regulative effect of hepatitis B virus (HBV) preS2 on the promoter of human acyl protein thioesterase 1 (APT1) gene .Methods The promoter sequence of human APT1 gene was identified applying the soft‐ware of bioinformatics .The APT1 promoter and HBV preS2 gene were amplified with PCR and cloned into pGL3 and pcDNA3 .1 (-) plasmids to construct the luciferase reporter gene plasmid of human APT1 gene promoter pGL3‐APT1 and the preS2 eukary‐otic expression plasmid pcDNA3 .1(-)‐preS2 ,respectively .The effect of the preS2 on the human APT1 gene promoter was exam‐ined by cotransfecting hepatocellular carcinoma cell HepG2 with pGL3‐APT1 and pcDNA3 .1(-)‐preS2 and measuring luciferase activities of the HepG2 cells .The statistical data were analyzed with independent‐samples t test .Results Both plasmids of pGL3‐APT1 and pcDNA3 .1(-)‐preS2 were confirmed by DNA sequencing to be accurately constructed as design .The luciferase activity of the pGL3‐APT1 was 1 .2 times (P<0 .01) that of the positive control plasmid pGL3‐Control .And the luciferase activity of the HepG2 cells cotransfected with pcDNA3 .1(-)‐preS2 and pGL3‐APT1 was 2 .6 times (P<0 .01) that of the HepG2 cells cotrans‐fected with the plasmid without preS2 gene pcDNA3 .1(-) and pGL3‐APT1 .Conclusion The human APT1 promoter cloned in the study has high promoter activity ;HBV preS2 activates human APT1 promoter .
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Objective To explore the effect of the gene silencing of phosphatidic acid-preferring phospholipase A1 (PA-PLA1) on insulin secretion in mouse insulin-secreting cell line MIN6. Methods The siRNA expression vector of mouse PA-PLA1 gene targeting was constructed using mouse PA-PLA1 mRNA sequence available in GenBank, and MIN6 cells were transfected with the vector. Fluorescence quantitative PCR and Western-blotwere applied to screen efficient RNAi-vector. After transfection with obtained efficient RNAi-vectors for 48 hours, glucose-stimulated insulin secretion experiments were conducted, and the changes of insulin secretion were examined. Results Four siRNA expression vectors of mouse PA-PLA1 gene targeting were confirmed to be successfully constructed by the analyses of enzyme cleavage and sequencing. The results of fluorescence quantitative PCR and Western blot analyses indicated that the siRNA expression vectorpGPU6-PA-PLA1-1885was the most effective RNAi-vector in the four vectors. The expression levels of the PA-PLA1 mRNA and protein of the MIN6 cells transfectedwith pGPU6-PA-PLA1-1885 decreased to 46.3% and 33.9% of that of the control, respectively, and meanwhile the insulin secretion levels of the cells decreased to 65.0% of that of the control (P < 0.05). Conclusion The gene silencing of phosphatidic acid-preferring phospholipase A1 might decrease insulin secretion in MIN6 cells.