Significance of biopterin induction in rats with postburn Staphylococcus aureus sepsis

It has been demonstrated that biopterin, an essential cofactor of nitric oxide synthase (NOS), plays an important role in the pathogenesis of endotoxin-induced shock, yet its biological significance in gram-positive sepsis remains unclear. In this study, we adopted a rat model of postburn Staphylococcus aureus sepsis to investigate the potential role of biopterin in the pathogenesis of gram-positive sepsis. Wistar rats were inflicted with a 20% total body surface area (TBSA) full-thickness scald injury followed by S. aureus challenge, and then guanosine triphosphate-cyclohydrolase I (GTP-CHI) mRNA expression and biopterin levels in liver, kidneys, lungs, and heart were determined. We found that after S. aureus challenge, GTP-CHI gene expressions and biopterin levels were markedly upregulated in various tissues. Meanwhile, multiple organ dysfunction was induced by S. aureus challenge. It was shown that cardiac GTP-CHI mRNA expression and renal BH(4) levels were positively correlated with MB isoenzyme of creatine kinase (CK-MB) and creatinine (r = 0.892, P = 0.0012 and r = 0.9423, P = 0.0015, respectively). These results suggested that thermal injury combined with S. aureus challenge could induce de novo biosynthesis of biopterin, which might play a role in the development of multiple organ dysfunction syndrome secondary to postburn sepsis.     

雷帕霉素对烫伤后金黄色葡萄球菌脓毒症大鼠白细胞介素10表达的影响

目的探讨脓毒症时应用雷帕霉素(RPM)干预对肝脏内源性白介素10(IL10)表达和急性肝损伤的影响。方法采用烫伤后金黄色葡萄球菌感染致严重脓毒症大鼠模型,50只大鼠随机分为正常对照组(n=5)、烫伤对照组(n=5)、烫伤脓毒症组(n=30)和RPM处理组(n=10)。采用逆转录多聚酶链式反应测肝组织IL10mRNA表达,并应用ELISA方法分别检测肝组织、血中IL10蛋白水平,同时观察肝功能指标的改变。结果与烫伤脓毒症组比较,RPM干预后0.5h肝组织中IL10mRNA表达和血中IL10蛋白水平明显升高(P<0.05),干预后2h则有不同程度的下降,但仍显著高于伤前水平(P<0.05或P<0.01)。同时,RPM干预组肝功能酶学指标明显改善。结论烫伤脓毒症早期应用RPM有助于保护IL10的内源性抗炎效应,从而减轻失控性炎症反应和急性肝损伤。     

The potential role of Staphylococcal enterotoxin B in rats with postburn Staphylococcus aureus sepsis

Staphylococcal enterotoxin B (SEB) is an important member of the superantigen family, which exerts a number of pathological effects in the human, as well as susceptible animals. The present study was conducted to observe the time course and tissue distribution of SEB in postburn Staphylococcus aureus infection; meanwhile, the relationship between SEB and multiple organ dysfunction was also studied. Eighty-six male Wistar rats were randomly divided into four groups as follows: normal control group (n = 10); scald control group (n = 10); postburn sepsis group (n = 50) in which rats inflicted with 20% total body surface area (TBSA) III degrees scald followed by SEB-producing S. aureus challenge were further divided into 0.5-, 2-, 6-, 12-, and 24-h subgroups, with 10 rats in each subgroup; and SEB monoclonal antibody (MAb) treatment group (n = 16) in which a dose of 4 mg/kg SEB MAb was given intravenously just before S. aureus challenge, and the rats were further divided into 2- and 6-h subgroups. It was found that after thermal injury combined with S. aureus infection, SEB was widely distributed to the liver, kidneys, lungs, and heart, exacerbating the pathophysiology of multiple organ dysfunction induced by postburn sepsis. At the same time, the gene and protein expressions of tumor necrosis factor-alpha (TNF-alpha) and interferon-gamma (IFN-gamma) were also markedly upregulated in various tissues. Early treatment with SEB-specific MAb-MAb2D(1)-could markedly decrease SEB levels in plasma as well as in various tissues, and could significantly reduce the 6-h mortality rate (17.64% [3/17] vs. 55.6% [20/36], P = 0.02). These data suggested that neutralization of SEB is effective in ameliorating S. aureus sepsis and subsequent multiple organ damage, which might be attributed to its inhibitory effect on inflammatory mediator formation.     

抑制JAK/STAT通路对烫伤后金黄色葡萄球菌脓毒症大鼠肝损害的影响

目的：研究JAK激酶／信号转导和转录激活子（JAK／STAT）通路对烫伤后金黄色葡萄球菌（金葡菌）感染致严重脓毒症大鼠肝损害的影响。方法：采用烫伤后金葡菌感染致严重脓毒症的大鼠模型,60只动物随机分为正常对照组,烫伤对照组,烫伤后金葡菌感染组,JAK2激酶抑制剂AG490和STAT3抑制剂雷帕霉素（RPM）处理组,采用逆转录多聚酶链式反应和酶联免疫吸附法,分别检测肝组织中肿瘤坏死因子－α（TNF－α）基因和蛋白表达,肝功能指标的改变。结果：AG490和RPM早期干预均能显著降低烫伤脓毒症大鼠肝组织TNF－αmRNA表达峰值（P均＜0．01）,AG490处理后2小时肝组织TNF－α的蛋白水平也有所下降,同时,血清丙氨酸转氨酶,天冬氨酸转氨酶亦显著降低（P＜0．01或P＜0．05）,结论：脓毒症早期抑制JAK／STAT通路的活化有助于减轻肝组织炎症反应及急性肝损害。     

JAK/STAT通路对烫伤脓毒症大鼠Toll样受体基因表达的调节作用

目的：探讨Janus激酶／信号转导和转录激活子（JAK／STAT）通路在烫伤脓毒症大鼠Toll样受体2（TLR2）基因表达调控中的意义。方法：Wistar大鼠38只随机分为正常对照组（n=6)、烫伤后金黄色葡萄球菌（金葡菌）感染组（n=12)、AG490拮抗组（n=20)和雷帕霉素（Rapamycin,RPM)拮抗组（n=10), 检测动物肝、肾、肺组织中TLR2和肿瘤坏死因子－α（TNF－α）基因表达的改变。结果：烫伤合并金葡菌攻击后0．5h和2h，动物肝、肾、肺组织中TLR2 mRNA表达显著增高（P＜0．05或P＜0．01）。RPM干预可有效抑制动脉肝、肾组织TLR2 mRNA表达，但对肺脏TLR2 mRNA表达无明显影响；而AG490拮抗组动物各组织中TLR2 mRNA表达与未干预组相比均无明显差异。烫伤合并金葡菌感染后2h大鼠肝、肺、肾组织TNF－α基因表达均显著升高（P均＜0．01）。给予RPM可明显抑制各组织中TNF－α mRNA表达（P＜0．05或P＜0．01），AG490拮抗组大鼠肝、肾组织中TNF－α表达亦均显著低于未拮抗组（P均＜0．01）。结论：烫伤后金葡菌感染可促进体内TLR2基因表达，STAT可能直接或通过其诱生的炎症介质参与了对TLR2 mRNA表达的调控。     

烫伤后金黄色葡萄球菌感染致严重脓毒症大鼠模型的建立

目的初步建立烫伤后金黄色葡萄球菌(金葡菌)感染所致严重脓毒症的动物模型。方法雄性Wistar大鼠行20%总体表面积Ⅲ度烫伤,于伤后24小时经腹腔注射对数生长期的金葡菌菌液4ml/kg(浓度为8×10     

生物喋呤对烫伤脓毒症大鼠一氧化氮合成的影响

目的：探讨生物喋呤BH4在金黄色葡萄球菌（简称金葡菌）脓毒症中的生物学效应，阐明BH4对一氧化氮（NO）诱生的调控作用。方法：76只Wistar大鼠随机分为正常对照组（n=10)、烫伤对照组（n=10)、烫伤后金葡菌感染组（n=40)和羟基嘧啶（DAHP）拮抗组（n=16)。无菌留取动物肝、肺组织采用RT－PCR方法检测三磷酸鸟苷环水解酶I（GTP－CHI）、诱生型一氧化氮合酶（iNOS)基因表达，同时测定组织中BH4和NO的水平。结果：烫伤后金葡菌感染组动物肝、肺组织中GTP－CHI基因表达明显上调，BH4产生显著增加，iNOS mRNA表达和NO的水平亦明显升高，DAHP组GTP－CHI基因表达上调和BH4合成NO的产生亦明显下降。结论：烫伤后金葡菌感染可诱导体内BH4的合成，BH4在基因和蛋白水平调控着iNOS所介导的NO大量生成，从而对金葡菌脓毒症的病理过程起促进作用。     

泛素-蛋白酶体途径对烫伤脓毒症大鼠肠道炎症反应与屏障功能的作用研究

目的研究泛素-蛋白酶体途径对烫伤脓毒症大鼠肠组织核转录因子-κB（NF-κB）活化、肿瘤坏死因子-α（TNF-α）表达以及血浆二胺氧化酶（DAO）活性的作用。方法采用30％总体表面积（TBSA）Ⅲ度烫伤合并内毒素攻击大鼠为模型模拟临床烫伤哝毒症。60只Wistar大鼠随机分为正常对照组、烫伤哝毒症模型组、泛素-蛋白酶体抑制剂N-乙酰亮氨酰亮氨酰正亮氨酸（ALLN）组、NF-κB抑制剂吡咯烷二硫基甲酸酯（PDTC）组。采用凝胶电泳迁移率改变分析法（EMSA）分析肠组织NF—κB活性；采用酶联免疫吸附法（ELISA）检测肠组织TNF-α含量；采用分光光度法检测血浆DAO活性。结果各组肠组织NF—κB活性于伤后1h均明显增强，并达到高峰（P均〈0．01）．之后呈现下降趋势；两种抑制剂均可显著降低伤后1h和2hNF-κB的活性。ALLN可明显降低伤后1h肠组织中TNF—α含量（P〈0.01）。两种抑制剂对伤后1h和2h血浆I）AO活性均无明显影响。结论早期使用泛素-蛋白酶体抑制剂可降低烫伤脓毒症大鼠肠组织NF—κB活性．降低肠组织中炎症反应．但对肠组织屏障功能无保护作用。     

Methicillin-resistant Staphylococcus aureus sepsis presenting with septic pulmonary emboli

Background: Septic pulmonary emboli are the result of infections that typically originate from an extrapulmonary source. Septic pulmonary embolus is a rare disorder that classically presents with fever, respiratory symptoms, and lung infiltrates. Objectives: Our objective is to share our experience of a rare diagnosis that was the result of a very common bacterium seen in the Emergency Department (ED). Case Report: We present a case of methicillin-resistant Staphylococcus aureus (MRSA) sepsis presenting as bilateral septic pulmonary emboli in a patient with undiagnosed acquired immunodeficiency syndrome. A 29-year-old Hispanic man presented to our ED with a history of abdominal pain and vomiting for 3 days and new onset of shortness of breath. The patient was seen 2 weeks prior for a simple abscess incision and drainage and was treated with trimethoprim/sulfamethoxazole. On the day of admission, a helical computed tomography scan of the chest was obtained, which revealed bilateral septic pulmonary emboli. The patient was admitted for intravenous antibiotic therapy and was subsequently found to have MRSA sepsis. Conclusion: Septic pulmonary embolus is a rare finding that is most commonly seen in patients who are immunocompromised. The patient fully recovered after aggressive antibiotic therapy.     

烫伤脓毒症大鼠肾脏核转录因子-kB活化与肾损伤关系的研究

目的 研究烫伤脓毒症大鼠肾脏核转录因子-kB（NF-kB）活化与肾损伤的关系。方法采用30％总体表面积Ⅲ度烫伤加内毒素攻击制备烫伤脓毒症大鼠模型。54只Wistar大鼠随机分为正常对照组、烫伤脓毒症1、2、6、12和24h组，烫伤脓毒症1、2和6h＋NF-kB抑制剂吡咯烷二硫基甲酸酯（PDTC）组。采用凝胶电泳迁移率改变分析法（EMSA）检测肾组织NF-kB活性；采用酶联免疫吸附法检测血浆及肾组织中肿瘤坏死因子-α（TNF-α）含量的变化；采用自动生化分析仪检测血肌酐（SCr）和尿素氮（BUN）含量。结果肾组织NF-kB活性于烫伤脓毒症后1h明显增强并达到高峰（P〈0．01），PDTC可显著降低烫伤脓毒症后1h NF-kB的活性。烫伤脓毒症后1h和2h血浆及肾组织中TNF-α水平均明显增高（P均〈0．01），PDTC可显著降低伤后血浆TNF-α水平（P均〈0．01），对肾组织中TNF-α水平影响不明显。烫伤脓毒症后BUN及SCr含量均明显增高（P均〈0．01），PDTC对BUN和SCr含量均无显著影响。结论NF-kB抑制剂可降低烫伤脓毒症大鼠肾组织NF-kB活性，但对肾脏功能无明显保护作用。     

Staphylococcus aureus endocarditis presenting as meningitis and mimicking meningococcal sepsis

A case of Staphylococcus aureus meningitis (SAM) secondary to endocarditis is presented. The presence of a petechial rash affecting the lower limbs led to an initial presumptive diagnosis of meningococcal meningitis. There were no stigmata of endocarditis at presentation, though these subsequently developed. Underlying endocarditis should be diligently sought in any patient presenting with spontaneous SAM, even if typical stigmata are initially absent. In view of the association with skin lesions and neurological complications, S. aureus endocarditis may mimic the classical presentation of meningococcal sepsis.     

Pulmonary vascular permeability changes in an ovine model of methicillin-resistant Staphylococcus aureus sepsis

Introduction

Endothelial dysfunction is a hallmark of sepsis, associated with lung transvascular fluid flux and pulmonary dysfunction in septic patients. We tested the hypothesis that methicillin-resistant Staphylococcus aureus (MRSA) sepsis following smoke inhalation increases pulmonary transvascular fluid flux via excessive nitric oxide (NO) production.

Methods

Ewes were chronically instrumented, and randomised into either a control or MRSA sepsis (MRSA and smoke inhalation) group.

Results

Pulmonary function remained stable in the control group, whereas the MRSA sepsis group developed impaired gas exchange and significantly increased lung lymph flow, permeability index and bloodless wet-to-dry weight-ratio (W/D ratio). The plasma nitrate/nitrite (NOx) levels, lung inducible nitric oxide synthases (iNOS) and endothelial nitric oxide synthases (eNOS), vascular endothelial growth factor (VEGF) protein expressions and poly-(ADP)-ribose (PAR) were significantly increased by MRSA challenge.

Conclusions

These results provide evidence that excessive NO production may mediate pulmonary vascular hyperpermeability in MRSA sepsis via up regulation of reactive radicals and VEGF.     

Effect of Rifampin on Nasal Carriage of Staphylococcus aureus

Initial studies indicate that rifampin may be useful for the treatment of Staphylococcus aureus infections. Because bacterial resistance to rifampin may develop rapidly, its widespread use could result in the emergence of a resistant flora. This study evaluates the effectiveness of rifampin in reducing the nasal carriage of S. aureus and the rate at which resistant mutants emerge in a tuberculosis hospital where the drug was widely used. Anterior nares cultures were performed four times over a 13-month period. Carriage rates of S. aureus were 1.7% in 227 patients receiving rifampin, 7.8% in 190 patients receiving other antituberculous therapy, and 14.2% in 98 hospital employees (rifampin-treated versus other patients, P < 0.003; rifampin-treated versus employees, P < 0.001; employees versus other patients, P = 0.157). All four strains of S. aureus isolated from patients on rifampin therapy were rifampin resistant. All 16 strains isolated from patients not on rifampin and 15 of 16 strains isolated from hospital personnel were susceptible. One instance of apparent spread of a rifampin-resistant organism occurred in a hospital attendant who had never received rifampin.     

烫伤脓毒症大鼠肾脏核转录因子-κB活化与肾损伤关系的研究

目的研究烫伤脓毒症大鼠肾脏核转录因子-κB (NF-κB)活化与肾损伤的关系.方法采用30%总体表面积Ⅲ度烫伤加内毒素攻击制备烫伤脓毒症大鼠模型.54只Wistar大鼠随机分为正常对照组、烫伤脓毒症1、2、6、12和24 h组,烫伤脓毒症1、2和6 h+NF-κB抑制剂吡咯烷二硫基甲酸酯(PDTC)组.采用凝胶电泳迁移率改变分析法(EMSA)检测肾组织NF-κB活性;采用酶联免疫吸附法检测血浆及肾组织中肿瘤坏死因子-α(TNF-α)含量的变化;采用自动生化分析仪检测血肌酐(SCr)和尿素氮(BUN)含量.结果肾组织NF-κB活性于烫伤脓毒症后1 h明显增强并达到高峰(P<0.01),PDTC可显著降低烫伤脓毒症后1 h NF-κB的活性.烫伤脓毒症后1 h和2 h血浆及肾组织中TNF-α水平均明显增高(P均<0.01),PDTC可显著降低伤后血浆TNF-α水平(P均<0.01),对肾组织中TNF-α水平影响不明显.烫伤脓毒症后BUN及SCr含量均明显增高(P均<0.01),PDTC对BUN和SCr含量均无显著影响.结论 NF-κB抑制剂可降低烫伤脓毒症大鼠肾组织NFκB活性,但对肾脏功能无明显保护作用.     

Effect of antibiotics on Staphylococcus aureus producing Panton-Valentine leukocidin

We examined the capacity of Staphylococcus aureus strains to release Panton-Valentine leukocidin (PVL) in the presence of antibiotics. No PVL was detected when S. aureus was incubated at inhibitory concentrations, while subinhibitory concentrations of oxacillin enhanced the PVL level; clindamycin, linezolid, and fusidic acid were inhibitory; and vancomycin had roughly no effect.