Temperature-Induced Unfolding Pathway of Staphylococcal Enterotoxin B:Insights from Circular Dichroism and Molecular Dynamics Simulation

In this study,circular dichroism(CD)and molecular dynamics(MD)simulation were used to investigate the thermal unfolding pathway of staphylococcal enterotoxin B(SEB)at temperatures of 298–371 and 298–500 K,and the relationship between the experimental and simulation results were explored.Our computational findings on the secondary structure of SEB showed that at room temperature,the CD spectroscopic results were highly consistent with the MD results.Moreover,under heating conditions,the changing trends of helix,sheet and random coil obtained by CD spectral fitting were highly consistent with those obtained by MD.In order to gain a deeper understanding of the thermal stability mechanism of SEB,the MD trajectories were analyzed in terms of root mean square deviation(RMSD),secondary structure assignment(SSA),radius of gyration(R_(g)),free energy surfaces(FES),solvent-accessible surface area(SASA),hydrogen bonds and salt bridges.The results showed that at low heating temperature,domain Ⅰ without loops(omitting the mobile loop region)mainly relied on hydrophobic interaction to maintain its thermal stability,whereas the thermal stability of domain Ⅱ was mainly controlled by salt bridges and hydrogen bonds.Under high heating temperature conditions,the hydrophobic interactions in domain Ⅰ without loops were destroyed and the secondary structure was almost completely lost,while domain Ⅱ could still rely on salt bridges as molecular staples to barely maintain the stability of the secondary structure.These results help us to understand the thermodynamic and kinetic mechanisms that maintain the thermal stability of SEB at the molecular level,and provide a direction for establishing safer and more effective food sterilization processes.

基于荧光生物传感技术检测牛奶中金黄色葡萄球菌肠毒素B

目的利用纳米金粒子(gold nanoparticles,AuNPs)荧光猝灭性能和核酸适配体的高亲和力,构建一种简便、灵敏的纳米金“Turn-on”型荧光生物传感方法检测牛奶中金黄色葡萄球菌肠毒素B(staphylococcal enterotoxins B,SEB)的方法。方法以AuNPs作为荧光体的能量受体(猝灭剂),荧光素-单链DNA(fluorescein-ssDNA,FAM-ssDNA)作为荧光能量供体,冷冻法制备AuNPs-SEB适配体复合物,基于AuNPsSEB适配体复合物/SEB/FAM-ssDNA的竞争性结合,构建纳米金“Turn-on”型荧光生物传感检测方法。对缓冲体系pH和反应时间等条件进行优化,以牛奶为代表对方法检测性能进行验证。结果在优化好的实验条件(pH 7.5、反应时间15 min和反应温度25℃)下,在10^(-1)~10^(4)ng/mL范围内,荧光强度与SEB质量浓度之间呈现良好的线性关系,其相关系数为0.995,检出限为0.062 ng/mL。应用于牛奶样品中SEB的测定,方法回收率为91.2%~108.0%,相对标准偏差在2.6%~5.2%范围之间。结论该纳米金“Turn-on”型荧光生物传感检测技术具有简便、灵敏和准确等优点,可为食品中污染物的检测提供一种可行的新方法。

葡萄球菌核酸酶样结构蛋白1/SLC7A11抑制铁死亡对骨肉瘤发生发展的影响

目的探讨葡萄球菌核酸酶样结构蛋白1(SND1)对骨肉瘤细胞生物学功能的影响,及其通过SLC7A11调控骨肉瘤细胞铁死亡的作用机制。方法检测人成骨细胞hFOB1.19以及骨肉瘤细胞系Saos-2、U2OS、HOS和143B中SND1的表达水平。采用小干扰RNA敲减骨肉瘤细胞HOS和143B中SND1的表达(si-SND1),采用CCK8法、细胞克隆形成实验、细胞迁移和侵袭实验探究SND1的表达对骨肉瘤细胞生物学功能的影响;调控骨肉瘤细胞中SND1以及SLC7A11基因的表达,探究SND1通过SLC7A1基因对骨肉瘤铁死亡介导的肿瘤细胞凋亡的影响。结果骨肉瘤细胞Saos-2、U2OS、HOS和143B中SND1 mRNA和蛋白的表达水平显著高于人成骨细胞hFOB1.19(P均<0.01)。与对照组比较,si-SND1转染显著降低HOS和143B细胞中SND1的表达水平(P均<0.01),且细胞活性显著降低,克隆形成数量显著减少,细胞迁移和侵袭能力显著降低(P均<0.001)。铁死亡诱导剂Erastin促进骨肉瘤HOS和143B细胞凋亡,而抑制剂Ferrostatin-1刺激上调细胞活性(P均<0.001)。敲减SND-1后使用Erastin可进一步降低骨肉瘤HOS和143B细胞活性,而使用Ferrostatin-1刺激后可显著恢复细胞活性(P均<0.001);Erastin处理后,si-SND1组细胞中铁离子和丙二醛表达增高,谷胱甘肽表达降低(P均<0.001)。体内实验结果显示,敲减SND1可以明显抑制143B裸鼠移植瘤的瘤体质量(P<0.001)。敲减SND1后骨肉瘤HOS和143B细胞中SLC7A11的表达水平显著减少(P均<0.001),且铁死亡水平升高(P<0.001,P=0.020)。结论骨肉瘤细胞中SND1表达显著增高,其可能通过上调SLC7A11的表达抑制铁死亡,进而促进骨肉瘤细胞活性。

葡萄球菌相关PS患者临床特征及预后分析

目的基于临床特征及预后探讨葡萄球菌相关化脓性脊柱炎(PS)患者的病理改变,为临床诊断治疗提供参考。方法回顾性选取2012年1月至2022年10月济南市第八人民医院收治的80例葡萄球菌相关PS患者,统计PS患者基本资料、病变节段分布、实验室指标、CT与MRI影像学特征、预后。结果80例葡萄球菌相关PS患者中,男36例,女44例,≥50岁63例,均存在一定程度腰背疼痛症状,视觉模拟量表(VAS)评分(7.38±0.23)分;病变节段主要分布在T8~T9(15例,18.75%)、L3~L4(12例,15.00%)、L2~L3(10例,12.50%);血小板、红细胞沉降率、白细胞计数、中性粒细胞、铁蛋白、C反应蛋白升高,血清血红蛋白、白蛋白下降。CT检查显示PS病变椎体骨质受损,周围软组织出现肿胀;CT增强扫描显示中心液化坏死区无强化,椎旁软组织边缘强化。MRI检查显示病变椎体异常信号灶,椎旁软组织肿胀,椎间盘破坏区异常信号灶,呈T1WI低信号、T2WI压脂高信号;MRI增强扫描可见明显强化,T2WI压脂高信号。经系统治疗后,所有PS患者VAS评分明显下降[(2.41±0.17)分],预后良好。结论葡萄球菌所引起PS均伴有不同程度腰背疼痛症状,病变节段以T8、T9及L3、L4为主,CT、MRI及C反应蛋白、红细胞沉降率升高可作为诊断PS的有效辅助检查,及时给予相关治疗可有效减轻疼痛,达到治愈效果。

葡萄球菌性烫伤样皮肤综合征的研究进展

葡萄球菌性烫伤样皮肤综合征(Staphylococcal scaled skin syndrome,SSSS)是一种潜在的、危及生命的急性表皮剥脱综合征。本病主要是由凝固酶阳性第Ⅱ组噬菌体金黄色葡萄球菌感染引起的皮肤病。SSSS的诊断主要根据临床表现,包括全身泛发性红斑、松弛性大疱、烫伤样表皮剥脱、口周放射性皲裂、尼氏征阳性以及黏膜不受累及。目前SSSS的治疗主要以抗金黄色葡萄球菌的抗生素为主,包括耐青霉素酶青霉素类、头孢菌素类、万古霉素、克林霉素等。近年来SSSS发病率以及发生并发症和死亡的风险在不断增加,本文对近年来有关SSSS的研究进展进行综述,以期为提高医务工作者对SSSS的认知和诊疗能力提供参考。

Determining of antibiotic resistance profile in Staphylococcus aureus isolates

Objective:To determine the pattern of antibiotic resistance among Staphylococcus aureus(S. aureus) isolates from clinical specimens and to identify community-acquired methicillin-resistant Staphylococcus aureus(CA-MRSA) in specimens that have been collected from patients referring to one of the hospitals of Ahvaz.Methods:S.aureus isolates from a hospital in Ahvaz were screened for resistance to various antibiotics including methicillin.The susceptibility of the isolates was determined by Kirby-Bauer disc diffusion method.The MRSA was also treated with ethidium bromide to find the origin of resistance.Results:Among the bacterial isolates,all of 11 S.aureus were resistant to methicillin and cefixime,2 were resistant to ciprofloxacin,6 were resistant to tetracycline and the reminder were sensitive or intermediate to other antibiotics.The treated isolates were reminded resistant to methicillin and this suggested that the plasmid was not the origin of resistance in these isolates.Conclusions:These results showed that infection due to MRSA is widespread in Ahvaz and with respect to the spread of vancomycin resistance among MRSA and appearance of overwhelming infections.It is necessary to identify continuously the profile of antibiotic resistance among S.aureus isolates in other regions and finding appropriate antibiotic for infection control and eradication.

Predictive Modeling for Growth and Enterotoxin Production of Staphylococcus aureus in Milk

Predictive microbiology was utilized to model Staphylococcus aureus （S. aureus） growth and staphylococcal enterotoxin A （SEA） production in milk in this study. The modifed logistic model, modifed Gompertz model and Baranyi model were applied to model growth data of S. aureus between 15℃ and 37℃. Model comparisons indicated that Baranyi model described the growth data more accurately than two others with a mean square error of 0.0129. Growth rates generated from Baranyi model matched the observed ones with a bias factor of 0.999 and an accuracy factor of 1.01, and ft a square root model with respect to temperature; other two modifed models both overestimated the observed ones. SEA amount began to be detected when the cell number reached106.4 cfu ？ mL-1, and showed the linear correlation with time. Besides, the rate of SEA production ftted an exponential relationship as a function of temperature. Predictions based on the study could be applied to indicate possible growth of S. aureus and prevent the occurrence of staphylococcal food poisoning.

Assessment of the inhibitory effects of sodium nitrite, nisin, potassium sorbate, and sodium lactate on Staphylococcus aureus growth and staphylococcal enterotoxin A production in cooked pork sausage using a predictive growth model

This study was conducted to analyze the effects of sodium nitrite,nisin,potassium sorbate,and sodium lactate against Staphylococcus aureus(S.aureus)growth and staphylococcal enterotoxins(SEs)production in cooked pork sausage by inoculating sausage samples containing preservative with an S.aureus strain producing staphylococcal enterotoxin A(SEA)and then storing them at 37℃ for 36 h.Samples were analyzed every 3 h to count the S.aureus colonies and to detect SEA.The modified Gompertz model was used to describe S.aureus growth in the samples under various conditions,and the preservatives with a significant antimicrobial effect were selected.In addition,the antimicrobial effects of the selected preservatives under various concentrations were tested.Results showed that sodium nitrite,nisin,and potassium sorbate had a weak effect against S.aureus growth and had no effect against SEA production,whereas sodium lactate could significantly inhibit S.aureus growth and SEA production.Moreover,the antimicrobial effect of sodium lactate was concentration-dependent,wherein sodium lactate concentration<12 g/kg showed no inhibitory effect,but when the concentration was increased to 24 g/kg,sodium lactate could effectively inhibit S.aureus growth and SEA production,and at 48 g/kg,sodium lactate had a significant inhibitory effect.

Emergence of staphylococcal cassette chromosome mec type Ⅰ with high-level mupirocin resistance among methicillin-resistant Staphylococcus aureus

Objective: To investigate the molecular epidemiology and antimicrobial resistance patterns of methicillin-resistant Staphylococcus aureus(MRSA) among healthcare workers and patients.Methods: MRSA isolates were recovered from nasal swabs collected at a tertiary care hospital of Nepal and confirmed on the basis of Gram staining, conventional biochemical tests, and PCR amplification of mec A gene. PCRs were also used for detection of the different resistance genes and staphylococcal cassette chromosome(SCC) mec types.Antibiotic susceptibility patterns of isolates were assessed by disc diffusion method and minimum inhibitory concentrations were determined by E-test.Results: A total of 29 MRSA were isolated from 536 nasal swabs(5.4%) of health care workers and patients at a tertiary care hospital in Nepal. All isolates were susceptible to amikacin, gentamicin, vancomycin(minimal inhibitory concentrations < 2 mg/m L), tigecycline, tetracycline, nitrofurantoin, rifampicin, quinupristin-dalfopristin, and linezolid. Among the 29 MRSA isolates, resistance to erythromycin(72%), ciprofloxacin(75%), co-trimoxazole(62%), clindamycin(10%), and chloramphenicol(10%) was found, and fifteen isolates(51%)exhibited high-level mupirocin resistance(minimal inhibitory concentrations > 1 024 mg/m L).Fourteen isolates were found harboring the mup A gene and one isolate was found carrying the novel mup B gene. High prevalence(68%) of SCCmec I type was found, followed by SCCmec V(13%) and SCCmec III(3%) among all the MRSA isolates.Conclusions: We found the emergence of SCCmec type I with high-level mupirocin resistance among MRSA in Nepal. Data also suggest that MRSA SCCmec type V strain has spread from the community to the hospital.

合肥地区耐甲氧西林金黄色葡萄球菌SCCmec分型及耐药性分析

目的 研究合肥地区临床分离的耐甲氧西林金黄色葡萄球菌(MRSA)携带mec基因簇的葡萄球菌盒式染色体(SCCmec)分型及药物敏感性,了解合肥地区MRSA流行株的耐药表型和分型特征。方法 从5所教学医院随机选取2016年1月至2021年12月的264株非重复MRSA菌株,利用头孢西丁纸片扩散法筛选MRSA,采用PCR扩增mec A基因,采用多重PCR进行MRSA的SCCmec分型分析。采用WHONET 5.6软件分析不同SCCmec型别MRSA菌株对抗菌药物的敏感性。结果 264株MRSA菌株中,SCCmecⅡ型156株(59.1%),Ⅳa型92株(34.8%),Ⅲ型4株(1.5%),12株(4.5%)未分型。SCCmecⅡ型和Ⅳa型MRSA对达托霉素、替加环素、利奈唑胺和万古霉素的敏感率均为100.0%。SCCmecⅡ型MRSA对环丙沙星、左氧氟沙星、莫西沙星和庆大霉素的耐药率高于SCCmecⅣa型,差异均有统计学意义(P均<0.05)。不同分型的MRSA菌株对红霉素、克林霉素、四环素、复方磺胺甲唑和利福平的耐药率差异无统计学意义(P均>0.05)。结论 合肥地区MRSA菌株SCCmec分型以Ⅱ型和Ⅳa型为主,不同分型MRSA对某些抗菌药物的耐药性存在差异,动态监测这类细菌的分型和药物敏感性有一定临床意义。

Ultrafast solvation dynamics at internal sites of staphylococcal nuclease investigated by site-directed mutagenesis

Internal solvation of protein was studied by site-directed mutagenesis, with which an intrinsically fluorescent probe,tryptophan, is inserted into the desired position inside a protein molecule for ultrafast spectroscopic study. Here we review this unique method for protein dynamics research. We first introduce the frontiers of protein solvation, site-directed mutagenesis, protein stability and characteristics, and the spectroscopic methods. Then we present time-resolved spectroscopic dynamics of solvation dynamics inside cavities of active sites. The studies are carried out on a globular protein, staphylococcal nuclease. The solvation at sites inside the protein molecule＇s cavities clearly reveals characteristics of the local environment. These solvation behaviors are directly correlated to enzyme activity.

STAPHYLOCOCCAL SCALDED SKIN SYNDROME: RETROSPECTIVE ANALYSIS OF 82 CASES

Objective To explore distinctive clinical manifestations and appropriate treatment, and assess prognosis of staphylococcal scalded skin syndrome （SSSS）. Methods A retrospective analysis was conducted of the data of 82 cases of SSSS hospitalized at Xinhua Hospital during the period from May 1993 to September 2003. Results The disease in all the 82 patients occurred in their first decade （mean 2.5 years）. Possible predisposing factors were found in 48 （58. 5% ）. Fever was present in 78 （95. 1% ）. Radial spokes of crusting around mouth were present in 80 （ 97. 6% ）. Erythema began on the face, especially around the mouth and eye in 63 （ 76. 8% ）. The course was acute in all cases and the eruptions quickly spread to the whole body within one day to two days. Of the 82 cases of SSSS, 47 were complete form of SSSS, 27 were abortive form of SSSS, and 8 were between the two forms. Staphylococcus aureus with positive staphylocoagulase was isolated from the possible primary infection sites including pharynx, eyelid, conjunctiva, nose, ear, and skin in 18 of 31 patients. Microbiological cultures of bullae and little pustulae developed after the onset were negative in 16 cases. All the 82 patients completely recovered after receiving antibiotic therapy （ ceftriaxone, oxacillin） alone or in combination with human immunoglobulin （IVIG） therapy. Additional IVIG therapy was used in those patients who had systemic involvements such as pneumonia, fever higher than 38. 5℃ or leukocytosis. Conclusion SSSS is a spectrum disease. Besides abortive and complete forms, presenting between the two forms a new form might be appeared in 8 cases who developed both scarlatiniform rash and flaccid bullae. The abortive form and complete form are usually misdiagnosed clinically. Radial spokes of crusting around mouth seem to be characteristic manifestation of SSSS. All the patients in this study had favorable prognosis after receiving prompt diagnosis and appropriate treatment.

THE EFFECT OF SUPERANTIGEN STAPHYLOCOCCALENTEROTOXIN B AND D-GALACTOSAMINE ON BALB/CMOUSE HEPATOCYTES

Objective To observe the role of superantigen staphylococcal enterotoxin B(SEB) andD - galactosamine (D - GalN) on Balb/c mouse hepatocytes and its mechanism. Methods After Balb/c mice wereinjected intraperitoneally with SEB, D- GalN or both, blood samples were collected and livers were removed at 2,6, 12, 24h. Patterns of hepatocellular death were studied morphologically and biochemically, circulating cytokines(TNF, IFN-γ) were determined, and mice mortality within 24h was assessed. Results SEB could induce thetypical apoptotic changes of hepatocytes morphologically and biochemically. The mechanism is probably associatedwith the production and release of Cytokines (such as TNF, IFN- γ, etc).D - GalN could induce hepatocytesapoptosis and degeneration at the same time. Besides this, we confirmed hepatocytes of the mice which wereadministered SEB and D - GalN developing apoptosis at 2, 6h, but after 12h hepatocytes were characterized bysevere injury, the mice mortality within 24h is 50%. Conclusion SEB or D - GalN alone could induce the typicalapoptotic changes of hepatocytes. SEB+D-GalN developed hepatocytes apoptosis in the early stage and necrosisin the later. It suggests that there is some relationship between hepatic cell apoptosis and necrosis, and massivehepatocyte apoptosis is the probably initiating step of acute hepatic necrosis in mice.

Effect and Mechanism of Superantigen Staphylococcal Enterotoxin Therapy for Mouse Gastric Tumor

The anti-tumor effect and mechanism of the staphylococcal enterotoxin A (SEA) were studied. The mouse gastric tumor model was produced by subcutaneously inoculating gastric tumor ceils (MGC80-3). The experimental group was treated with SEA, and the control group was treated with normal saline. The percentage of tumor generation and tumor mass was measured. The results showed that the percentage of the tumor generation in the SEA-treated mice was lower than in the control group, but there was no significant difference (P>0. 05). However, the tumor mass in the experimental group was significantly lighter than in the control group, with the difference being very significant (P<0. 001). There were more CD4+ T cells and CD8+ T cells in the tumor of the mice treated with SEA than those of the control group. SEA has an obvious anti-tumor effect on mice gastric tumor. The mechanism might be that SEA induces the effect of superantigen-dependent cell mediated cytotoxicity to the tumor cells.

The Akt Pathway Inhibitor Degeulin Prevents Staphylococcal Enterotoxin B Induced Splenocyte Proliferation and Inflammation

Staphylococcal Enterotoxin B (SEB) is considered a potential biological weapon. It is toxic by both inhalation and ingestion. Effects of ingestion include fever, vomiting and diarrhoea, while inhalation may additionally result in chest pain, dyspnoea, pulmonary oedema and respiratory failure. Severe exposure may be fatal and treatment relies on symptomatic support. At a cellular level, SEB up-regulates T-cell proliferation leading to a pathological inflammatory response. Deguelin, a rotenoid isolated from the African plant Mundulea sericea (Leguminosae), has been shown to reduce cellular proliferation by inhibiting the phosphoinositide 3-kinase/Akt (PI3K/Akt) signalling pathway. Using isolated murine splenocytes, we have demonstrated that treatment with deguelin reduces SEB inducing T cell proliferation by 60%. Deguelin treatment also decreased IL-2 and CCL2 secretion by splenocytes exposed to SEB. We demonstrate that targeting cellular proliferation can significantly reduce inflammation after SEB exposure and suggest that anti-proliferatives may have a role as potential generic medical counter measures if superantigens are used as biological weapons.

Spectroscopic Characterization of Staphylococcal Nuclease Mutants with Tryptophan at Internal Sites

Tryptophan （Trp） is an intrinsic fluorescent probe for detecting the site-specified dynamics inside/outside protein. It is found that the Trp can easily be inserted in desired sites of protein, which affects the integrity of the overall structure. To evaluate this effect, we design thirteen double point mutants of staphylococcal nuclease, each of which has a single Trp residue planted at an internal site. The studies on Trp fluorescence, ANS-binding fluorescence, far- and near-UV CD spectra, and enzymatic activity are carried out. It is found that the mutation at the hydrophobic core of protein generates molten globular state conformation, which is a loose structure compared to their original compactness in wild type （WT）. Its enzyme activity and surface hydrophobicity are also affected. The studies show that by proper site designing and external binding, Trp mutagenesis is a suitable method for carrying out the study on site specified dynamics of proteins.

Diversity and Distribution of Staphylococcal Chromosomal Cassettes Mec (SCCmec) Types I, II and III in Coagulase-Negative Staphylococcal Strains Isolated from Surfaces and Medico-Technical Materials of the University Hospital of Abomey-Calavi/Sô-Ava

The coagulase-negative staphylococci (CoNS) have long been considered to be low pathogenicity. The possibility of a horizontal transfer of resistance and virulence genes from S. aureus to CoNS could increase the pathogenicity of these bacteria. The objective of this work is to contribute to a better knowledge of the pathogenicity of (CoNS) strains isolated from surfaces and medico-technical materials of the University Hospital of Abomey-Calavi/Sô-Ava. Seventy strains of CoNS isolated from surfaces and medico-technical materials of the University Hospital of Abomey-Calavi were tested for methicillin resistance. The resistance to methicillin was evaluated phenotypically by the resistance of the strains to cefoxitin and then confirmed by the search for the mecA gene using PCR. The genes encoding staphylococcal chromosomal cassette (SCCmec) types I, II and III originally found in S. aureus were tested in CoNS by multiplex PCR using specific primers. All the strains studied showed resistance to methicillin. However, only 28.5% (20/70) carried the mecA gene. SCCmec was identified in only 17.14% (12/70) of these strains. Four strains carried mecA gene as well as one of the three types of SCCmec searched. SCCmec types I, II and III were identified in CoNS strains studied. SCCmec type I was the most frequent chromosomal cassette in mecA+ strains, only or in association with another SCCmec. The study also revealed methicillin-resistant strains carrying SCCmec lacking the mecA gene. Finally, 60% (12/20) of the strains were found to be non-typeable. Our results show that CoNS strains present a high resistance to methicillin and the source of this resistance in the CoNS of our study is not only the mecA gene. There is also a high diversity of SCCmec, justified by a large number of non-typeable CoNS strains. The mecA− SCCmec+ methicillin-resistant strains deserve to be sequenced for further studies.

益生菌对鸡葡萄球菌性关节炎的预防效果研究

试验旨在探究益生菌对鸡葡萄球菌性关节炎的预防效果。试验自病料中分离鉴定了1株金黄色葡萄球菌,构建鸡葡萄球菌性关节炎模型,筛选对分离株敏感的抗生素和益生菌并比较了其对鸡葡萄球菌性关节炎的预防效果。结果显示,自14株优质益生菌中筛选出了1株对分离的金黄色葡萄球菌具有体外抑制功能的益生菌BLCC2-0410,自18种常见抗生素中筛选出了对分离的金黄色葡萄球菌具有高敏感性的抗生素阿莫西林。攻菌后第7 d,攻菌对照组与抗生素组鸡血清免疫球蛋白G(IgG)抗体水平显著低于益生菌组和空白对照组(P<0.05),血清白细胞介素-6(IL-6)含量显著高于益生菌组和空白对照组(P<0.05);攻菌对照组、抗生素组和益生菌组鸡血清白细胞介素-10(IL-10)含量均显著高于空白对照组(P<0.05),益生菌组鸡血清IL-10含量显著高于其余3组(P<0.05)。攻菌后第14 d,攻菌对照组与抗生素组鸡血清IgG抗体水平显著低于益生菌组和空白对照组(P<0.05);攻菌对照组与抗生素组鸡血清IL-6按量显著高于空白对照组(P<0.05);益生菌组鸡血清IL-10含量显著高于其余3组(P<0.05)。抗生素组鸡的感染率达到为23.33%,益生菌组感染率为13.33%。研究表明,BLCC2-0410可明显提高机体IgG水平,下调促炎因子IL-6水平,上调抑炎因子IL-10水平,降低金黄色葡萄球菌感染率和炎症反应,鸡葡萄球菌性关节炎具有一定的预防作用。

Neonatal Staphylococcal Scalded Skin Syndrome:A Case Report

Objective:To summarize the clinical features,diagnosis,and treatment of neonatal staphylococcal scalded skin syndrome(SSSS).Methods:The clinical data with SSSS was analyzed,and the related literature was reviewed.Results:The acute onset of the disease was characterized by generalized erythema,epidermis exfoliation,skin non-touch,radial chapping around the mouth,and positive Nissl sign.The culture of binocular secretions and neck exudates showed Staphylococcus aureus and was diagnosed as SSSS.According to the results of drug sensitivity of secretions and exudates,vancomycin was selected for anti-infective treatment,and skincare and symptomatic support were given simultaneously.The child was cured and discharged after ten days of treatment.Conclusion:SSSS belongs to neonatal acute and critical illness.Improving etiological examination and timely targeted anti-infective treatment is the key to correct diagnosis and recovery.

基于裁剪适配体的纳米金比色法用于金黄色葡萄球菌肠毒素A的可视化检测

目的:筛选适配体作为分子识别原件,基于纳米金的盐效应构建生物传感器,实现金黄色葡萄球菌肠毒素A(staphylococcal enterotoxin A,SEA)的快速定量检测。方法:采用分子对接和分子动力学模拟对SEA适配体进行截短指导和结果预测,利用纳米金显色法验证模拟结果,对SEA适配体优化并将其作为分子识别原件,优化反应体系,探讨SEA质量浓度与吸光度比值间的关系,构建一种可视化的SEA快速检测分析方法,并对方法的准确度、精密度和特异性进行评价。结果:筛选出一条序列短、亲和力高、特异性强且稳定的SEA适配体,建立了一种基于纳米金比色的SEA可视化检测方法,检出限低,加标回收结果满意。结论:采用分子模拟能有效提高适配体筛选效率,本方法可用于SEA快速检测。