[Effects of cerium oxide nanoenzyme-gelatin methacrylate anhydride hydrogel in the repair of infected full-thickness skin defect wounds in mice].

Objective: To investigate the effects of cerium oxide nanoenzyme-gelatin methacrylate anhydride (GelMA) hydrogel (hereinafter referred to as composite hydrogel) in the repair of infected full-thickness skin defect wounds in mice. Methods: This study was an experimental study. Cerium oxide nanoenzyme with a particle size of (116±9) nm was prepared by hydrothermal method, and GelMA hydrogel with porous network structure and good gelling performance was also prepared. The 25 µg/mL cerium oxide nanoenzyme which could significantly promote the proliferation of human skin fibroblasts and had high superoxide dismutase activity was screened out. It was added to GelMA hydrogel to prepare composite hydrogel. The percentage of cerium oxide nanoenzyme released from the composite hydrogel was calculated after immersing it in phosphate buffer solution (PBS) for 3 and 7 d. The red blood cell suspension of mice was divided into PBS group, Triton X-100 group, cerium oxide nanoenzyme group, GelMA hydrogel group, and composite hydrogel group, which were treated with corresponding solution. The hemolysis of red blood cells was detected by microplate reader after 1 h of treatment. The bacterial concentrations of methicillin-resistant Staphylococcus aureus (MRSA) and Escherichia coli were determined after being cultured with PBS, cerium oxide nanoenzyme, GelMA hydrogel, and composite hydrogel for 2 h. The sample size in all above experiments was 3. Twenty-four 8-week-old male BALB/c mice were taken, and a full-thickness skin defect wound was prepared in the symmetrical position on the back and infected with MRSA. The mice were divided into control group without any drug intervention, and cerium oxide nanoenzyme group, GelMA hydrogel group, and composite hydrogel group applied with corresponding solution, with 6 mice in each group. The wound healing was observed on 3, 7, and 14 d after injury, and the remaining wound areas on 3 and 7 d after injury were measured (the sample size was 5). The concentration of MRSA in the wound exudation of mice on 3 d after injury was measured (the sample size was 3), and the blood flow perfusion in the wound of mice on 5 d after injury was observed using a laser speckle flow imaging system (the sample size was 6). On 14 d after injury, the wound tissue of mice was collected for hematoxylin-eosin staining to observe the newly formed epithelium and for Masson staining to observe the collagen situation (the sample size was both 3). Results: After immersion for 3 and 7 d, the release percentages of cerium oxide nanoenzyme in the composite hydrogel were about 39% and 75%, respectively. After 1 h of treatment, compared with that in Triton X-100 group, the hemolysis of red blood cells in PBS group, GelMA hydrogel group, cerium oxide nanoenzyme group, and composite hydrogel group was significantly decreased (P<0.05). Compared with that cultured with PBS, the concentrations of MRSA and Escherichia coli cultured with cerium oxide nanoenzyme, GelMA hydrogel, and composite hydrogel for 2 h were significantly decreased (P<0.05). The wounds of mice in the four groups were gradually healed from 3 to 14 d after injury, and the wounds of mice in composite hydrogel group were all healed on 14 d after injury. On 3 and 7 d after injury, the remaining wound areas of mice in composite hydrogel group were (29±3) and (13±5) mm2, respectively, which were significantly smaller than (56±12) and (46±10) mm2 in control group and (51±7) and (38±8) mm2 in cerium oxide nanoenzyme group (with P values all <0.05), but was similar to (41±5) and (24±9) mm2 in GelMA hydrogel group (with P values both >0.05). On 3 d after injury, the concentration of MRSA on the wound of mice in composite hydrogel group was significantly lower than that in control group, cerium oxide nanoenzyme group, and GelMA hydrogel group, respectively (with P values all <0.05). On 5 d after injury, the volume of blood perfusion in the wound of mice in composite hydrogel group was significantly higher than that in control group, cerium oxide nanoenzyme group, and GelMA hydrogel group, respectively (P<0.05). On 14 d after injury, the wound of mice in composite hydrogel group basically completed epithelization, and the epithelization was significantly better than that in the other three groups. Compared with that in the other three groups, the content of collagen in the wound of mice in composite hydrogel group was significantly increased, and the arrangement was also more orderly. Conclusions: The composite hydrogel has good biocompatibility and antibacterial effect in vivo and in vitro. It can continuously sustained release cerium oxide nanoenzyme, improve wound blood perfusion in the early stage, and promote wound re-epithelialization and collagen synthesis, therefore promoting the healing of infected full-thickness skin defect wounds in mice.

[Periconceptional maternal homocysteine and birth weight outcomes in offspring: a prospective cohort study].

Objective: To quantify the associations between periconceptional maternal homocysteine (HCY) and offspring's birth weight and risk of small for gestational age (SGA) infant. Methods: The 19 984 mother-child pairs in this prospective cohort study were recruited from the Shanghai preconception cohort; the infants were delivered from 1st September 2016 to 11th November 2022. A standardized questionnaire was used to collect the mothers' demographic information, medical history, dietary supplement use, and maternal complications during pregnancy, and their serum samples were collected. Serum HCY, folate, and vitamin B12 were measured using chemiluminescent microparticle immunoassay based on serum sample drawn at enrollment. Birth weight data were obtained from medical records. Multiple imputation methods were applied to handle missing data in key variables. Multivariable linear regression and Poisson regression models were used to analyze the relationship between maternal HCY concentration during the periconceptional period and the birth weight and SGA risk of the offspring. Results: A total of 9 452 pairs were enrolled preconceptionally and the remaining 10 532 pairs were enrolled in early pregnancy. The proportion of mothers whose pregnancy age was greater than 35 years was 9.2% (1 832/19 984), the proportion of primiparous women was 76.5% (15 283/19 984), the proportion of pre-pregnancy overweight and obesity was 14.0% (2 804/19 984), the proportion of using folic acid supplements before pregnancy was 21.4% (4 272/19 984), and the proportion of those who supplemented with folic acid during early pregnancy was 85.2% (8 976/10 532); gestational diabetes mellitus was in 6.2% (1 245/19 984), gestational hypertensive syndrome in 3.6% (711/19 984). The birth weight of the offspring was (3 297±468) g, and there were 1 962 SGA children (9.8%). The HCY concentration in the overall population in appropriate for gestational age during the periconceptional period was (7.9±3.2) µmol/L, with (8.3±3.7) µmol/L in the preconception subgroup and (7.3±2.4) µmol/L in the early pregnancy subgroup. After adjustment for the covariates of perinatal demographic information, adverse pregnancy outcomes, serum folate and vitamin B12, increased maternal periconceptional HCY was significantly associated with lower offspring birth weight (ß=-2.30, 95%CI -4.43--0.16, P=0.035). Only the early pregnancy subgroup was significantly associated with lower offspring birth weight (ß=-7.39, 95%CI-11.50--3.21, P<0.001). No association was found between peripregnancy HCY and offspring SGA risk. However, elevated HCY in early pregnancy was associated with an increased risk of SGA in the offspring (RR=1.05, 95%CI 1.01-1.08, P=0.002). Periconceptional vitamin B12 was a mediator of the association between HCY and offspring birth weight, accounting for 16.5%, 41.2% and 5.4% of its total effect in the overall periconceptional population, the pre-pregnancy subgroup and the early pregnancy subgroup, respectively. Conclusions: Maternal periconceptional HCY level is associated with lower birth weight in offspring, but not with the risk of SGA. Elevated maternal HCY in early pregnancy subgroup may be associated with increased risk of SGA in offspring.

[Research advances of sepsis biomarkers].

Sepsis is a life-threatening condition for patients. Biomarkers can be used for the diagnosis, treatment, and prognostic assessment of sepsis. In recent years, new biomarkers for sepsis have been discovered, and more than 250 biomarkers have been identified so far. The complexity of the sepsis process and the increased sensitivity of various detection techniques will lead to the emergence of new biomarkers. However, there is still a lack of specific diagnostic biomarkers and effective therapeutic approaches for sepsis in clinical practice. Therefore, the search for reliable biomarkers and the evaluation of the role of biomarkers in sepsis will undoubtedly aid in clinical decision-making. This article reviews the advances on research of sepsis biomarkers in order to improve understanding of current biomarkers of sepsis, and provide reference for the application of biomarkers in clinical diagnosis, treatment, and prognosis of sepsis.

[Discussion on classification and diagnostic nomenclature of burn infection].

Infection is the most common complication after burn injury and one of the leading causes of death in burn patients. Thus, how to effectively prevent the occurrence and development of infection is an important task in treating burns. Till now, there are still many controversies in the clinical definition, diagnosis, and treatment of infection, especially burn infection. The authors of this article put forward their opinions and views on this subject, hoping to deepen the readers' understanding of burn infection.

[Association between extracellular water/body cell mass ratio and cognitive impairment in patients on maintenance hemodialysis].

Objective: To explore the correlation between extracellular water/body cell mass (ECW/BCM) ratio and cognitive impairment (CI) in patients on maintenance hemodialysis (MHD). Methods: A multicenter, cross-sectional study was conducted in Guizhou Province. All adult MHD patients in hemodialysis centers of 18 hospitals in Guizhou Province between June and October 2020 were included. Cognitive function was assessed with the Mini-Mental State Examination (MMSE) score. The ECW and BCM was derived from bioelectrical impedance, and the ECW/BCM ratio was calculated. The patients were divided into four groups based on the quartile of ECW/BCM ratio. Multivariate logistic regression analysis and subgroup analysis were conducted. Results: A total of 3 160 patients were included in the final analysis, of which 761 (24.1%) developed CI. There were 1 868 males (59.1%) and 1 292 females (40.9%), and the mean age was (55±15) years. Multivariate logistic regression analysis showed that the risk of CI in ECW/BCM Q3 group was 1.55 times (95%CI: 1.03-2.34, P=0.035) of that in group Q1, while the risk of CI in Q4 group was 1.62 times of that in group Q1 (95%CI: 1.05-2.51, P=0.029). Subgroup analysis showed that there was an interaction between previous cerebrovascular event and ECW/BCM on CI (P for interaction=0.04). Patients with a previous history of cerebrovascular events had a higher risk of CI than those without. Among those with no previous cerebrovascular events, the risk of CI in group Q4 was 1.62 times of that in group Q1 (95%CI: 1.19-2.20), while the risk of CI in group Q4 was 7.17 times of that in group Q1 (95%CI: 1.59-32.35) in those with previous cerebrovascular events. Conclusion: Increased ECW/BCM ratio is associated with increased CI risk in patients with MHD, and the risk was more obvious in those with previous history of cerebrovascular events.

[Comparative analysis of clinical diagnosis application of two intrauterine adhesion scoring criteria].

Objective: To explore the similarities and differences of China Society of Gynecology Endoscopy (CSGE) and American Fertility Society (AFS) intrauterine adhesion (IUA) scoring criteria on IUA grading and their predictive value of reproductive prognosis. Methods: From January 2016 to January 2019, a total of 1 249 patients were diagnosed with IUA by hysteroscopy at Beijing Obstetrics and Gynecology Hospital. Totally, 378 patients with complete clinical data were enrolled, and the results diagnosed by CSGT and AFS scoring criteria were compared and analyzed.And follow-up for 2 years, the pregnancy rate and live birth rate were statistical analysis. Results: (1) The grade of IUA according to AFS and CSGE scoring criteria was less consistent (κ=0.295, P<0.001). Compared with AFS, the proportion of severe IUA cases diagnosed by CSGE was significantly lower [45.8% (173/378) vs 15.1% (57/378); RR=0.22, 95%CI: 0.15-0.30, P<0.01); the proportions of both mild and moderate IUA cases were significantly higher (RR=4.16, 95%CI: 2.38-7.14; RR=2.38, 95%CI: 1.75-3.23; both P<0.01). (2) The pregnancy rates of mild, moderate and severe IUA diagnosed according to CSGE were 11/13, 64.5% (147/228), 31.8% (7/22), live birth rates were 11/13, 54.8% (125/228) and 22.7% (5/22), respectively; there were statistically significant differences between the groups (all P<0.01). The pregnancy rates of mild, moderate and severe IUA diagnosed based on AFS were 3/3, 66.9% (97/145) and 56.5% (65/115), respectively, with no statistically significant difference between the groups (P>0.05). (3) IUA grades based on both CSGE and AFS criteria were significantly negatively correlated with pregnancy rates and live birth rates (CSGE: r=-0.210, r=-0.226; AFS: r=-0.130, r=-0.147; all P<0.05). Univariate logistic regression analysis showed that CSGE had higher OR for both pregnancy rates and live birth rates compared to AFS (3.889 vs 1.657, 3.983 vs 1.554, respectrvely). Conclusions: Compared with AFS, the IUA grade based on CSGE is better related with reproductive prognosis, suggesting that the CSGE standard might be more objective and comprehensive and has better predictive value for reproductive prognosis, thus avoiding overdiagnosis and overtreatment.

[Research advances on the interaction between Pseudomonas aeruginosa bacteriophages and the host].

Pseudomonas aeruginosa is the most common pathogen of burn wound infection. It can encode a variety of virulence factors and is highly pathogenic, which can lead to poor prognosis and high mortality. In order to research a new method to combat Pseudomonas aeruginosa infection, researchers have observed a wide range of interactions between the bacteriophages and the host. Bacteriophages influence and even dominate the structure, movement, and metabolism of host bacteria through a variety of mechanisms, catalyze the evolution of the host, and are also an important factor in host environmental adaptability and pathogenicity. In this paper, the interaction between Pseudomonas aeruginosa bacteriophages and the host is reviewed from the single cell level and the population level. Understanding these interactions could provide new idea for the treatment of Pseudomonas aeruginosa clinical infections, provides a basis for future development of antimicrobial agents and guides the treatment of burn infections.

[Clinical application of extracorporeal membrane oxygenation in the treatment of burn patients with acute respiratory distress syndrome: a retrospective analysis and systematic review].

Objective: To analyze the clinical effect of extracorporeal membrane oxygenation (ECMO) in the treatment of burn patients with acute respiratory distress syndrome (ARDS). Methods: The retrospective observational study and the systematic review were applied. From March 2014 to July 2020, five burn patients with ARDS received ECMO treatment in the First Affiliated Hospital of Army Medical University (the Third Military Medical University). All the five patients were male, aged from 40 to 62 years. The average total burn surface area was 58.8% total body surface area (TBSA) and four cases had severe inhalation injury. Patient's ECMO starting time, duration and mode, and whether successfully weaned or the cause of death, and others. were recorded. Furthermore, the changes of oxygenation and infection before, during, and after utilizing ECMO were analyzed. PubMed and Web of Science from the establishment of each database to August 2021 were searched using "Extracorporeal Membrane Oxygenation", "ECMO", "burn", "inhalation" as the search terms and "Title/Abstract" as the field to retrieve the clinical articles that meet the selection criteria . Basic information were extracted from the articles, including sample size, gender, age, total burn area, inhalation injury, the indication of ECMO, the start and lasting time of ECMO, ECMO mode, rate of successful weaning, complications of ECMO, mortality, the combined application of continuous renal replacement therapy (CRRT). Results: Five patients started venovenous ECMO on an average of 10.2 days after injury and lasted an average of 180.4 hours. Three out of 5 patients were weaned successfully with one patient survived. Four patients died of multiple organ dysfunction syndrome (MODS) and septic shock. Compared with those before ECMO treatment, the arterial oxygen partial pressure (PaO2) and oxygen saturation in arterial blood (SaO2) of three successfully weaned patients obviously increased during and after ECMO treatment. The fraction of inspired oxygen (FiO2) decreased below 50% and PaO2/FiO2 ratio increased above 200 mmHg (1 mmHg=0.133 kPa) during and after ECMO. Furthermore, lactic acid and respiratory rate decreased, basically. Compared with those before ECMO, PaO2 and SaO2 in the other two patients during ECMO, who failed to be weaned, continuously decreased while lactic acid increased. Before and during ECMO, the PaO2/FiO2 ratios of unsuccessfullg weaned cases were less than 200 mmHg, and partial pressure of carbon dioxide in arterial blood (PaCO2) were more than 40 mmHg. Compared with those before ECMO, there were no significant changes in body temperature during and after ECMO, which were less than 38 ℃. Compared with those before ECMO, the leucocyte number (the index without this in unsuccessfully weaned cases was omitted, the same as below) in four patients showed a significant decrease during ECMO, but rose after removal of ECMO. The proportion of neutrophils in three patients were slightly higher during ECMO than before ECMO, and did not change significantly after removal of ECMO. Compared with those before ECMO, platelet counts in three patients were significantly reduced during ECMO, and all five patients during ECMO were below normal levels. Compared with those before ECMO, the procalcitonin levels in four deaths were significantly increased during ECMO. Catheter culture of microorganism was performed in three successfully weaned patients, all of which were negative. A total of 13 literature were included, ranging from 1990 to 2019. The sample size in 6 studies was less than 10, and the sample size in 4 studies was between 10 and 20, and only 2 literatures had a sample size larger than 50. ECMO was applied in 295 burn patients with overall mortality of 48.8% (144/295), including 157 adults and 138 children. The most common indication of ECMO was severe ARDS. Among 157 adult burn patients (95 males and 65 females), 36 cases had inhalation injury. The average burn area was 27%-37%TBSA in 5 reported studies and was more than 50%TBSA in 2 reported studies. The most common mode was venovenous ECMO. ECMO treatment began 26.5 hours to 7.4 days after injury and lasted from 90 hours to 18 days, and the rate of successful weaning ranged from 50% to 100%. The most common complications were bleeding and infection. The mortality was 52.9% (83/157). MODS and sepsis were the leading causes of death. Among 138 pediatric burn patients (77 boys and 61 girls), 29 patients had inhalation injury. The average burn area was 17%-50.2%TBSA in 3 studies. ECMO treatment lasted from 165.2 hours to 324.4 hours. Bleeding was the most common complication. The mortality was 44.2% (61/138). Conclusions: ECMO is an effective strategy for the salvage treatment of burns complicated with ARDS. Furthermore, the prevention and treatment of bleeding, infection and organ dysfunction should be emphasized during the use of ECMO. More importantly, evidence-based guidelines for burns are urgently needed to further improve the clinical effect of ECMO.

[Research advances on the development and application of clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR-associated protein system].

Clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR-associated (Cas) protein system, as an emerging gene editing system, can be divided into class 1 and class 2 systems according to the number of Cas protein. The CRISPR/Cas9 in class 2 system can cleave target nucleic acid only with the help of Cas9 protein and single-stranded guide RNA, which is currently the most widely used CRISPR/Cas system. In addition to gene editing in the treatment of genetic diseases, a variety of CRISPR/Cas system derived technologies have vast application prospect in the fields of disease-related gene screening, gene expression regulation, and rapid detection, prevention, and control of pathogens. This article summarizes the discovery process of CRISPR/Cas system and applications of several major CRISPR/Cas derived technologies, aiming to provide a reference for researchers in the field of life science.

[Multidrug resistant organisms in burn intensive care unit: strategies and opinions].

Infections caused by multidrug-resistant (MDR) organisms can significantly increase the mortality of patients with burn injury. Management and prevention of infections by MDR organisms in burn intensive care unit (ICU) become challenging problems in clinical treatment of severe burn patients. The prevention and control of nosocomial infections are important measures to minimize or avoid the spread of MDR organisms in burn ICU. It is recommended to optimize the therapeutic regimen for infections by MDR organisms and achieve the best therapeutic effect by monitoring the characteristics of organisms in local burn unit, evaluating and reducing the susceptibility of burn patients and using the antibiotics rationally. In addition, rapid and accurate diagnosis and non-antibiotic treatment are expected to be the directions for breakthrough in the future.

[Epidemiological investigation and analysis of etiological characteristics of infection on 3 067 hospitalized pediatric patients with burns].

Objective: To investigate the epidemiological characteristics and etiological distribution of infection on 3 067 hospitalized pediatric patients with burns, and explore the prevention and treatment strategy of pediatric burns. Methods: A cross-sectional survey was conducted. An analysis was performed on the data of 3 067 hospitalized pediatric patients with burns who met the inclusion criteria and were admitted to the First Affiliated Hospital of Army Medical University (the Third Military Medical University) from January 2012 to December 2020, including gender, age, causative factors, locations and severities of burns, seasons of accidents, and the type, source of tissue or body fluid, and drug resistance of pathogenic bacteria. API bacterial identification batten and automatic microbial identification system were applied for pathogen identification. Drug sensitivities of top 3 consistent ratio pathogen identifed were tested with minimum inhibitory concentration and disk diffusion method. WHONET 5.6 software was applied to analyze the data. Results: There were 3 067 hospitalized pediatric patients with burns, including 1 768 boys and 1 299 girls. The majority of pediatric burn patients were >1 and ≤4 years, accounting for 72.9% (2 236/3 067), and the minority of pediatric burn patients were >8 and ≤12 years, accounting for 4.9% (150/3 067). Moderate burns and severe burns of pediatric burn patients accounted for the majority parts, and the proportions of the two were close. The top cause of pediatric burns was scald, accounting for 81.6% (2504/3 067). Extremities were the most common burn sites in that of entire 3 254. The most pediatric burns occurred in winter, accounting for 29.4% (903/3 067). A total of 1 018 strains of pathogenic bacteria were collected from pediatric burn patients, all of which were non-repeated isolates. The pathogens with top five consistent ratio were Staphylococcus aureus, Pseudomonas aeruginosa, Acinetobacter baumannii, Enterobacter cloacae, and Escherichia coli, among which Staphylococcus aureus ranked the first every year. The pathogens were mainly isolated from the wound exudate, accounting for 81.34% (828/1 018). Staphylococcus aureus from 2012 to 2020 showed no resistance to vancomycin, linezolid or teicoplanin while Staphylococcus aureus isolated in 2019 was 100% resistant to macrolides, penicillin, aminoglycosides, and quinolones. Pseudomonas aeruginosa was not resistant to polymyxin B. Acinetobacter baumannii showed a high rate of drug resistance to most antibiotics. Conclusions: Among the pediatric burn patients admitted to the First Affiliated Hospital of Army Medical University (the Third Military Medical University) from 2012 to 2020, the majority are male children aged >1 and ≤4 years with moderate burns. Scalds are the leading cause; and extremities are the common burn sites; and the most pediatric burns occurre in winter. Staphylococcus aureus from wound exudate is the primary pathogen of burn wound infections in pediatric patients.

[Research advances on application of single-cell RNA sequencing in islet cell biology].

After the first single-cell RNA sequencing of human islet in 2016, a large number of analysis of RNA sequencing at single-cell level on mouse and human islets emerged, which has brought new progress to the research of islet cell biology. It has been proved that single-cell RNA sequencing can characterize rare types of endocrine cells, find the cellular heterogeneity of typical endocrine cells and new cell subtypes, analyze the differences of endocrine cells among species, and describe different states of various types of islet cells in developmental processes and metabolic diseases more accurately. Although the detection efficiency of single-cell RNA sequencing for low abundance transcripts is relatively low at present, with the improvement of technology and the progress of analytical methods, this technology will undoubtedly become a powerful tool to explore the cellular heterogeneity, development, and biological characteristics of metabolic diseases.

[Work flow of clinical microbiology laboratory in the epidemic of the coronavirus disease 2019].

The burn microbiology laboratory of the author's unit is a level Ⅱ biosafety laboratory, which is mainly responsible for handling clinical microbial samples from our department and other departments in the hospital. Since the outbreak of the coronavirus disease 2019, in order to ensure the normal operation of routine work and the safety of medical staff, the microbiology laboratory has actively adjusted the daily work flow. The detailed work flow is summarized as follows to provide references for the safety protection of peer in clinical microbiology laboratory.

[Clinical application effect of modified nasopharyngeal swab sampling for 2019 novel coronavirus nucleic acid detection].

Objective: To study the clinical application effect of modified nasopharyngeal swab sampling for 2019 novel coronavirus nucleic acid detection. Methods: This study covered the period from January 14 to March 1, 2020.The supine position method and the protective face screen were used to collect nasopharyngeal swabs from February 24 onwards, before which, the nasopharyngeal swabs were collected by sitting position method. All the patients who were diagnosed with suspected/confirmed 2019 novel coronavirus infection were admitted from February 19 with the nasopharyngeal swabs collected outside the hospital before admission. (1) Thirty-four swabbing operators meeting the inclusion criteria of the study were recruited in this retrospective cohort study. They were grouped according to the collection method of nasopharyngeal swabs. Sixteen operators of Wuhan Taikang Tongji Hospital who applied the supine position method and the protective face screen were included in supine position method+ protective face screen group (15 males and 1 female, aged 34-49 years); 18 operators (12 from the First Affiliated Hospital of Army Medical University (the Third Military Medical University), 1 from Wuhan Jiangxia Mobile Cabin Hospital, 5 from the East District of People's Hospital of Wuhan University) who applied the traditional sitting position method were included in sitting position method group (2 males and 16 females, aged 25-49 years). In supine position method+ protective face screen group, when collecting sample, the patient lay flat and wore a special protective face screen for nasopharyngeal swab sampling, with neck slightly extending and face turning to the opposite side of the operator about 10°. The self-designed questionnaire was used to investigate the cooperation, the incidence of nausea, coughing, sneezing, and struggling of patients evaluated by the operators, the operation time for a single swab sample, the fear of operation and the perceived exposure risk of operators in the two groups. (2) Sixty-five patients (22 males and 43 females, aged 25-91 years) admitted to Wuhan Taikang Tongji Hospital who successively received the sitting position method and supine position method+ protective face screen for nasopharyngeal swabs sampling and with complete nucleic acid detection results were included. The positive rates of nucleic acid detection by the two sampling methods of nasopharyngeal swabs of the patients were statistically analyzed. (3) Forty-one patients who could express their feelings accurately were selected out of those 65 patients (12 males and 29 females, aged 27-83 years). The comfort of patients in the process of sampling by the two methods was investigated. (4) Thirty-four patients (10 males and 24 females, aged 25-83 years) with two or more consecutive negative results of nucleic acid detection of nasopharyngeal swabs by sitting position method were selected from the above 65 patients. The positive rate of nucleic acid detection of nasopharyngeal swab of patients by supine position method+ protective face screen, i. e. negative to positive rate was statistically analyzed. Data were statistically analyzed with t test, Wilcoxon signed rank test, and chi-square test. Results: (1) Compared with those of sitting position method group, the cooperation score of patients evaluated by the operators in supine position method+ protective face screen group was significantly higher (Z=-4.928, P<0.01), the incidence of nausea, choking cough, sneezing, and struggling of patients evaluated by the operators, and the fear of operation score and the perceived exposure risk score of operators in supine position method+ protective face screen group were significantly lower (Z=-5.071, -5.046, -4.095, -4.397, -4.174, -5.049, P<0.01), and the operation time for a single swab sample in supine position method+ protective face screen group was significantly longer (t=223.17, P<0.01). (2) The positive rate of nucleic acid detection of nasopharyngeal swabs by supine position method+ protective face screen was 60.00% (39/65), which was obviously higher than 41.54% (27/65) by sitting position method (χ(2)=4.432, P<0.05). (3) The comfort score of the 41 patients during nasopharyngeal swabs sampling by supine position method+ protective face screen was significantly higher than that by sitting position method (Z=-5.319, P<0.01). (4) Of the 34 patients with two or more consecutive negative results of nucleic acid detection of nasopharyngeal swabs by sitting position method, the rate of negative to positive of nucleic acid detection was 26.47% (9/34) after sampling by supine position method+ protective face screen. Conclusions: Compared with the traditional sitting position method, detection of 2019 novel coronavirus nucleic acids of nasopharyngeal swabs collected by supine method combined with protective face screen is worth promoting, because of its better comfort of patients, low exposure risk for operators, in addition to reducing in the false negative result to some extent, which may help reduce false recurrence of discharged patients.

[Recommendations for normalizing the medical practices of burn treatment during the outbreak of coronavirus disease 2019].

2019 novel coronavirus (2019-nCoV) is one of the beta coronaviruses and is identified as the pathogen of the severe " coronavirus disease 2019 (COVID-19)" in 2019. China manages COVID-19 according to the reguirement of the highest level infectious diseases in China. Currently, the prevention and control of COVID-19 in China is at a critical period. Burn Department as an emergency discipline is confronted with risk of 2019-nCoV infection. Based on the guidelines for the diagnosis and treatment of COVID-19 (6th trial edition), in combination with the latest literature at home and abroad, the features of the COVID-19, the recommendations for the COVID-19 prevention and control issued by the National Health Commission of China, and the management experience of COVID-19 diagnosis and treatment of other related disciplines, we put forward some recommendations for the medical practices of burn treatment during the outbreak of the COVID-19 in outpatient and emergency, inpatient treatment, and the management of operation theatres and wards, etc. We hope these recommendations could benefit the medical professionals in the field of burn treatment and relevant hospital management during the outbreak of COVID-19, improve burn treatment, and avoid or reduce the risk of infection of medical staff.

[Effects of phage therapy on sepsis].

Phages can fight against sepsis through directly lysing the bacteria and influence the patients' self-response to the pathogens through the immunomodulation effects in a coordinated way. Under the situation of the rising antimicrobial resistance, phage has attracted wide attention of researchers at home and abroad. Along with the development of researches and clinical related trials, we believe phage therapy in sepsis treatment can be expected soon in the future.

[Analysis of distribution and drug resistance of pathogens isolated from 159 patients with catheter-related bloodstream infection in burn intensive care unit].

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.

[Analysis of the pathogenic characteristics of fungal bloodstream infection in severe burn patients].

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.

[Epidemiology investigation of carbapenems-resistant Klebsiella pneumoniae in burn care unit].

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 bla(CTX-M-10), bla(SHV), bla(TEM), bla(CTX-M-14), bla(ACT), and bla(KPC) were all above 92.5%. (5) According to PFGE, the 27 CRKP strains had 6 types (A, A(1), A(2), 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 A(1), A(2), 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.

[Preliminary application of real-time fluorescence recombinase polymerase amplification in Candida albicans].

Objective: To explore the preliminary application effect of real-time fluorescence recombinase polymerase amplification (RPA) in the detection of Candida albicans. Methods: (1) Candida albicans standard strain and negative control bacteria of Pseudomonas aeruginosa, Staphylococcus aureus, Acinetobacter baumannii, Escherichia coli, Candida glabrata standard strains of respectively 1 mL were collected and their DNA were extracted by yeast/bacterial genomic kit. The specificity of polymerase chain reaction (PCR), real-time fluorescent quantitative PCR, and real-time fluorescence RPA in detecting Candida albicans were analyzed. (2) One Candida albicans standard strain and one negative control bacteria of Candida glabrata standard strain were collected, resuscitated, and counted. Candida albicans was diluted 10 times to 1×10(7) to 1×10(1) colony-forming unit (CFU)/mL. The DNA of the two bacteria were extracted as experiment (1). The sensitivity of PCR, real-time fluorescent quantitative PCR, and real-time fluorescence RPA in detecting Candida albicans were analyzed. The number of cycles for amplification curve to reach the threshold in real-time fluorescent quantitative PCR, and time of appearance of specific amplification curve in real-time fluorescence RPA were recorded and compared with the results in PCR. The detection limit and rate of the above-mentioned 3 methods in detecting Candida albicans were analyzed, and the correlation between concentration of Candida albicans in real-time fluorescence RPA and detection time was analyzed. (3) One standard strain of Candida albicans was collected, and the DNA was extracted as experiment (1) and detected by PCR, real-time fluorescent quantitative PCR, and real-time fluorescence RPA. The total detection time of the above-mentioned 3 methods was recorded, respectively. (4) The DNA of 31 clinical samples of suspected Candida albicans infection and 1 clinical sample of Candida albicans collected from cotton swab were extracted, PCR and real-time fluorescence RPA were carried out, and the positive detection rates of the above-mentioned methods were calculated. The DNA of the clinical samples with positive results in both PCR and real-time fluorescence RPA were extracted by yeast/bacterial genomic kit, chelex-100 boiling method, and repeatedly freeze-thawing with liquid nitrogen method, and real-time fluorescence RPA and PCR were carried out. The negative control bacteria was Candida glabrata in real-time fluorescence RPA, while negative control bacteria in PCR were the same as experiment (1). The positive results in PCR and real-time fluorescence RPA were observed and time for amplification curve to reach the fluorescence threshold in real-time fluorescence RPA was recorded, respectively. Data were processed with linear correlation analysis and t test. Results: (1) Three methods showed positive results in detecting standard strain of Candida albicans, and none of the 5 negative control bacteria showed positive results. (2) As the concentration of bacterial solution of Candida albicans decreased, the number of cycles for the amplification curve to reach the threshold increased in real-time fluorescent quantitative PCR, the time for appearance of specific amplification curve prolonged in real-time fluorescence RPA, and brightness of the gel strip weakened in PCR. None of the negative control bacteria in the above-mentioned 3 detection methods showed corresponding positive results. The detection limit of Candida albicans in real-time fluorescence RPA, PCR, and real-time fluorescent quantitative PCR was 1×10(1) CFU/mL. There was a significant negative correlation between the concentration of Candida albicans and the detection time in real-time fluorescence RPA (r=-0.95, P<0.01). The positive detection rates of PCR and real-time fluorescent quantitative PCR for Candida albicans of 1×10(1) to 1×10(7) CFU/mL were 100%. The positive detection rate of real-time fluorescence RPA for Candida albicans of 1×10(1) CFU/mL was 78%, and the positive detection rate of real-time fluorescence RPA for Candida albicans of 1×10(2) to 1×10(7) CFU/mL was 100%. (3) The total time of PCR, real-time fluorescent quantitative PCR, and real-time fluorescence RPA detection for Candida albicans was 133, 93, and 35 min, respectively. (4) The positive detection rate of real-time fluorescence RPA for 31 clinical samples of suspected Candida albicans infection was 32.26% (10/31), which was slightly lower than 35.48% (11/31) of PCR. Eleven clinical samples showed positive results both in real-time fluorescence RPA and PCR detection. No positive result was observed in the negative control bacteria detected both by real-time fluorescence RPA and PCR. The DNA was extracted by yeast/bacterial genomic extraction kit and chelex-100 boiling method for real-time fluorescence RPA detection. The time for the amplification curve to reach the threshold was (438±13) and (462±12) s, respectively, which was close (t=1.32, P>0.05). The DNA was extracted by repeatedly freeze-thawing with liquid nitrogen method for real-time fluorescence RPA, and the time for the amplification curve to reach the threshold in real-time fluorescence RPA was (584±15) s, which was significantly longer than that in the other 2 methods (t=7.55, 6.39, P<0.01). Conclusions: Real-time fluorescence RPA has advantages of rapid detection, simple operation, high sensitivity, and good specificity in detecting Candida albicans, which is worthy of clinical application.