One-hit wonder: Late after burn injury,granulocytes can clear one bacterial infection but cannot control a subsequent infection

ObjectiveBurn injury induces an acute hyperactive immune response followed by a chronic immune dysregulation that leaves those afflicted susceptible to multiple secondary infections. Many murine models are able to recapitulate the acute immune response to burn injury, yet few models are able to recapitulate long-term immune suppression and thus chronic susceptibility to bacterial infections seen in burn patients. This has hindered the field, making evaluation of the mechanisms responsible for these susceptibilities difficult to study. Herein we describe a novel mouse model of burn injury that promotes chronic immune suppression allowing for susceptibility to primary and secondary infections and thus allows for the evaluation of associated mechanisms.MethodsC57Bl/6 mice receiving a full-thickness contact burn were infected with Pseudomonas aeruginosa 14 days (primary infection) and/or 17 days (secondary infection) after burn or sham injury. The survival, pulmonary and systemic bacterial load as well as frequency and function of innate immune cells (neutrophils and macrophages) were evaluated.ResultsFollowing secondary infection, burn mice were less effective in clearance of bacteria compared to sham injured or burn mice following a primary infection. Following secondary infection both neutrophils and macrophages recruited to the airways exhibited reduced production of anti-bacterial reactive oxygen and nitrogen species and the pro-inflammatory cytokineIL-12 while macrophages demonstrated increased expression of the anti-inflammatory cytokine interleukin-10 compared to those from sham burned mice and/or burn mice receiving a primary infection. In addition the BALF from these mice contained significantly higher level so of the anti-inflammatory cytokine IL-4 compared to those from sham burned mice and/or burn mice receiving a primary infection.ConclusionsBurn-mediated protection from infection is transient, with a secondary infection inducing immune protection to collapse. Repeated infection leads to increased neutrophil and macrophage numbers in the lungs late after burn injury, with diminished innate immune cell function and an increased anti-inflammatory cytokine environment.     

铜绿假单胞菌注射液对肺癌A549细胞自噬及PI3K/Akt通路的影响

目的探究铜绿假单胞菌注射液(PA-MSHA)对肺癌A549细胞自噬及磷脂酰肌醇-3激酶(PI3K)/蛋白激酶B(Akt)通路的影响。方法体外培养人肺癌A549细胞,随机分为空白对照组、LY294002组(加入20μmol/L LY294002),PA-MSHA干预组(加入0.5×10^9/mL、1.0×10^9/mL、2.0×10^9/mL PA-MSHA)。干预培养48 h后,MTT法检测各组细胞活性,平板克隆形成实验检测各组细胞增殖能力,透射电子显微镜观察各组细胞自噬情况,Western blot检测各组细胞中自噬相关蛋白p62、LC3Ⅰ、LC3Ⅱ及PI3K/Akt通路相关蛋白PI3K、Akt、p-PI3K、p-Akt表达。结果与空白对照组相比,LY294002组、0.5×10^9/mL、1.0×10^9/mL、2.0×10^9/mL PA-MSHA组细胞增殖抑制率、LC3Ⅱ/LC3Ⅰ蛋白表达显著升高(P<0.05),自噬体个数增加,细胞克隆形成率、p62、p-PI3K/PI3K、p-Akt/Akt蛋白表达显著降低(P<0.05);与LY294002组相比,0.5×10^9/mL、1.0×10^9/mL PA-MSHA组细胞增殖抑制率、LC3Ⅱ/LC3Ⅰ蛋白表达显著降低(P<0.05),自噬体个数减少,细胞克隆形成率、p62、p-PI3K/PI3K、p-Akt/Akt蛋白表达显著升高(P<0.05);与0.5×10^9/mL、1.0×10^9/mL PA-MSHA组相比,2.0×10^9/mL PA-MSHA组细胞增殖抑制率、LC3Ⅱ/LC3Ⅰ蛋白表达显著升高(P<0.05),自噬体个数增加,细胞克隆形成率、p62、p-PI3K/PI3K、p-Akt/Akt蛋白表达显著降低(P<0.05)。结论PA-MSHA可能通过调控PI3K/Akt信号通路,促进肺癌A549细胞自噬,抑制细胞增殖。     

Two-dimensional gel electrophoresis (2D-GE) image analysis based on CellProfiler: Pseudomonas aeruginosa AG1 as model

Two-dimensional gel electrophoresis (2D-GE) is an indispensable technique for the study of proteomes of biological systems, providing an assessment of changes in protein abundance under various experimental conditions. However, due to the complexity of 2D-GE gels, there is no systematic, automatic, and reproducible protocol for image analysis and specific implementations are required for each context. In addition, practically all available solutions are commercial, which implies high cost and little flexibility to modulate the parameters of the algorithms. Using the bacterial strain, Pseudomonas aeruginosaAG1 as a model, we obtained images from 2D-GE of periplasmic protein profiles when the strain was exposed to multiple conditions, including antibiotics. Then, we proceeded to implement and evaluate an image analysis protocol with open-source software, CellProfiler. First, a preprocessing step included a bUnwarpJ-Image pipeline for aligning 2D-GE images. Then, using CellProfiler, we standardized two pipelines for spots identification. Total spots recognition was achieved using segmentation by intensity, whose performance was evaluated when compared with a reference protocol. In a second pipeline with the same program, differential identification of spots was addressed when comparing pairs of protein profiles. Due to the characteristics of the programs used, our workflow can automatically analyze a large number of images and it is parallelizable, which is an advantage with respect to other implementations. Finally, we compared six experimental conditions of bacterial strain in the presence or absence of antibiotics, determining protein profiles relationships by applying clustering algorithms PCA (Principal Components Analysis) and HC (Hierarchical Clustering).     

泛耐药铜绿假单胞菌感染的抗感染思路分析

目的 探讨泛耐药铜绿假单胞菌肺炎的药物治疗方案。方法 以临床药师参与一例大面积烧伤患者的泛耐药铜绿假单胞菌肺炎的抗感染方案为例，结合最新临床研究进展，探讨抗菌药物雾化吸入在治疗泛耐药细菌导致的肺部感染中的应用。 结果 泛耐药铜绿假单胞菌导致的肺部感染通常选择联合治疗，抗菌药物雾化吸入作为一种联合或补充治疗，可以提高肺部药物浓度，减少全身不良反应，但使用时仍需慎重选择临床适应症。 结论 临床药师应积极参与抗感染方案的制定，针对患者制定个体化的给药方案。     

应用噬菌体控制假单胞菌的研究进展

假单胞菌属细菌中的部分菌株是动植物和人类的致病菌，也是食品的腐败菌，会导致动植物和人类的高死亡率和严重的食品安全事故。噬菌体作为一种细菌性病毒，特异性高、自我增殖快且无副作用。这些特性使其成为了解决细菌性问题的新思路和新方法。本文就利用噬菌体防控假单胞菌属致病菌和腐败菌在食品、水产、植物、医疗等方面的研究和应用进行综述，以便为后期的深入研究提供一定的参考。     

204株耐碳青霉烯铜绿假单胞菌的临床特点和耐药性分析

摘要： 目的 分析204株耐碳青霉烯铜绿假单胞菌的临床分布、 患者因素和耐药性, 为临床合理有效使用抗菌药物提供科学依据。方法 采取VITEK-2 Compact全自动微生物分析系统对2017年1月—12月我院分离的204株耐碳青霉烯铜绿假单胞菌进行鉴定及药敏试验, 分析临床分布、 标本来源。比较患者不同因素对耐碳青霉烯铜绿假单胞菌检出率的影响。比较呼吸道与非呼吸道分离株、 ICU与普通病房分离株的耐药性差异。结果 204株耐碳青霉烯铜绿假单胞菌分布于ICU 97株、 普通病房107株。标本来源以呼吸道为主, 共169株, 占82.84%; 非呼吸道35株,占17.16%。有基础疾病、 近90 d使用抗菌药物、 进行侵入性操作以及菌株检出时间距入院时间＞48 h的患者耐碳青霉烯铜绿假单胞菌的检出率均分别高于无基础疾病、 近90 d未使用抗菌药物、 未进行侵入性操作以及菌株检出时间距入院时间≤48 h的患者 （P＜0.01）。呼吸道标本组对头孢他啶、 环丙沙星的耐药率显著低于非呼吸道标本组 （P＜ 0.05）, 余12种抗菌药物耐药率差异无统计学意义 （P＞0.05）。普通病房分离株对替卡西林/克拉维酸、 头孢哌酮/舒巴坦、 阿米卡星、 头孢吡肟、 庆大霉素耐药率显著低于ICU病房 （P＜0.05）, 余9种抗菌药物耐药率差异无统计学意义（P＞0.05）。204株耐碳青霉烯铜绿假单胞菌对亚胺培南、 美罗培南耐药率差异无统计学意义 （P＞0.05）。结论 耐碳青霉烯铜绿假单胞菌感染多发生于院内, 在ICU、 普通病房, 呼吸道、 非呼吸道的耐药形势已同样严峻, 应引起临床高度重视。     

Evaluating biapenem dosage regimens in intensive care unit patients with Pseudomonas aeruginosa infections: a pharmacokinetic/pharmacodynamic analysis using Monte Carlo simulation

This study was conducted to identify optimal dosage regimens and estimate pharmacokinetic/pharmacodynamic (PK/PD) characteristics of short-infusion (SI) versus extended-infusion (EI) biapenem against Pseudomonas aeruginosa infections in Chinese intensive care unit (ICU) patients. A total of 85 strains of P. aeruginosa were collected, and the minimum inhibitory concentration (MIC) of biapenem was measured by the serial two-fold agar dilution method. We designed four frequently used clinical regimens: biapenem 300?mg I.V. q12h, q8h, and q6h, and 600?mg q12h. The Monte Carlo Simulation (MCS) was performed using previously published pharmacokinetic data to calculate the probability of target attainment (PTA) and the cumulative fraction of response (CFR) of these regimens as an SI (0.5?h) and an EI (1?h, 2?h, 3?h, and 4?h).For a target of 40%fT_>MIC (serum drug concentration remains above the MIC for a dosing period), none of the regimens achieved any CFRs>90% for P. aeruginosa, multidrug–resistant P. aeruginosa (MDR-PA) and even non–MDR-PA. The traditional biapenem SI regimens most commonly seen in clinical practice were insufficient in treating both MDR and non-MDR P. aeruginosa in ICU patients. However, biapenem 600?mg q12h over 2–4?h EI regimens could achieve CFR>90% with 20%fT_>MIC. Clinical trials should aim to validate the potentially greater PK/PD index with higher, more frequent doses and longer extended infusions.     

铜绿假单胞菌的群体感应系统及其抑制剂研究进展

群体感应系统(quorum sensing system, QS)是一种微生物细胞与细胞间的交流系统。铜绿假单胞菌是该系统的典型代表,可调控细菌产生对抗生素的耐药、形成生物膜、产生毒力因子,并且减弱宿主的免疫应答。群体感应系统抑制剂(quorum sensing inhibitors, QSIs)在不影响细菌生长的前提下可降低细菌的毒性,且增强细菌生物膜对抗生素治疗的敏感性,这些特点使QSIs成为目前抗感染领域的研发热点。本文就铜绿假单胞菌的群体感应系统及QSIs的研究进展进行了综述。     

铜绿假单胞菌院内呼吸道感染的耐药性分析

目的探讨由铜绿假单胞菌引起医院获得性肺炎的特点及对其抗生素的疗效。方法对2001年1月至2003年12月在我院确诊的19例铜绿假单胞菌所致医院获得性肺炎进行研究:包括其相关危险因素、药敏试验、抗生素使用情况和治疗效果。结果19例大多数存在严重基础疾患,抗生素的不合理应用和免疫功能低下等因素。铜绿假单胞菌对头孢比肟、亚胺培南/西司他丁、哌拉西林/他唑巴坦、阿米卡星敏感率较高,其他常用抗生素耐药。我院最常应用的是亚胺培南/西司他丁,治疗效果较好。结论铜绿假单胞菌医院获得性肺部感染者均存在明确易感因素,成功的治疗有赖于抗生素的正确选用。