重组体pET-28a-alkB/E.coli降解页岩油泥石油烃的功能研究

为了降解页岩油泥中的石油烃,构建基因工程菌,表达石油烃降解关键酶以提高油泥的降解效果。以Pseudomonas qingdaonensis基因组为模板扩增alkB基因,连接至载体pET-28a,转化至E.coli BL21(DE3)中,SDS-PAGE和Western-blot鉴定表达的外源蛋白。pET-28a-alkB/E.coli处理原油和页岩油泥,采用气相色谱法评估降解效果。发现alkB基因在大肠杆菌中能表达外源蛋白,且14 d原油及页岩油泥的降解率分别为47.5%和47.1%,表明重组体pET-28a-alkB/E.coli具备降解页岩油泥石油烃的功能。

Exploring the modulatory role of bovine lactoferrin on the microbiome and the immune response in healthy and Shiga toxin‑producing E.coli challenged weaned piglets

Background Post-weaned piglets suffer from F18+Escherichia coli(E.coli)infections resulting in post-weaning diar-rhoea or oedema disease.Frequently used management strategies,including colistin and zinc oxide,have contrib-uted to the emergence and spread of antimicrobial resistance.Novel antimicrobials capable of directly interacting with pathogens and modulating the host immune responses are being investigated.Lactoferrin has shown promising results against porcine enterotoxigenic E.coli strains,both in vitro and in vivo.Results We investigated the influence of bovine lactoferrin(bLF)on the microbiome of healthy and infected weaned piglets.Additionally,we assessed whether bLF influenced the immune responses upon Shiga toxin-producing E.coli(STEC)infection.Therefore,2 in vivo trials were conducted:a microbiome trial and a challenge infection trial,using an F18+STEC strain.BLF did not affect theα-andβ-diversity.However,bLF groups showed a higher relative abundance(RA)for the Actinobacteria phylum and the Bifidobacterium genus in the ileal mucosa.When analysing the immune response upon infection,the STEC group exhibited a significant increase in F18-specific IgG serum levels,whereas this response was absent in the bLF group.Conclusion Taken together,the oral administration of bLF did not have a notable impact on theα-andβ-diversity of the gut microbiome in weaned piglets.Nevertheless,it did increase the RA of the Actinobacteria phylum and Bifi-dobacterium genus,which have previously been shown to play an important role in maintaining gut homeostasis.Furthermore,bLF administration during STEC infection resulted in the absence of F18-specific serum IgG responses.

Impact of an oligosaccharide-based polymer on the metabolic profiles and microbial ecology of weanling pigs experimentally infected with a pathogenic E.coli

Background Our previous study has reported that supplementation of oligosaccharide-based polymer enhances gut health and disease resistance of pigs infected with enterotoxigenic E.coli(ETEC)F18 in a manner similar to carbadox.The objective of this study was to investigate the impacts of oligosaccharide-based polymer or antibiotic on the host metabolic profiles and colon microbiota of weaned pigs experimentally infected with ETEC F18.Results Multivariate analysis highlighted the differences in the metabolic profiles of serum and colon digesta which were predominantly found between pigs supplemented with oligosaccharide-based polymer and antibiotic.The relative abundance of metabolic markers of immune responses and nutrient metabolisms,such as amino acids and carbohydrates,were significantly differentiated between the oligosaccharide-based polymer and antibiotic groups(q<0.2 and fold change>2.0).In addition,pigs in antibiotic had a reduced(P<0.05)relative abundance of Lachnospiraceae and Lactobacillaceae,whereas had greater(P<0.05)Clostridiaceae and Streptococcaceae in the colon digesta on d 11 post-inoculation(PI)compared with d 5 PI.Conclusions The impact of oligosaccharide-based polymer on the metabolic and microbial profiles of pigs is not fully understood,and further exploration is needed.However,current research suggest that various mechanisms are involved in the enhanced disease resistance and performance in ETEC-challenged pigs by supplementing this polymer.

Correlation analysis of human papillomavirus E6/E7 mRNA detection with diagnosis,prognosis and recurrence risk in patients with cervical epithelioma

BACKGROUND Cervical intraepithelial neoplasia(CIN)is an important precursor of cervical cancer.Early detection and treatment can reduce the incidence of cervical cancer.AIM To investigate the detection rate of human papillomavirus(HPV)E6/E7 mRNA in cervical tissue of patients with different types of epithelial cell neoplasia(CIN)and its relationship with CIN progression and diagnosis.METHODS One hundred women with HPV infection detected by cervical exfoliation cytology between January 2022 and January 2023 were retrospectively selected.These patients were graded CIN based on colposcopy and cervical pathology.The positive expression rates of HPV E6/E7 mRNA and HPV[polymerase chain reaction(PCR)-reverse dot crossing]were compared among all groups.Patients with HPV E6/E7 mRNA expression in the grade 1 CIN group were followed up for 1 yr.The relationship between atypical squamous epithelium and high malignant epithelial neoplasia was investigated by univariate and multivariate analysis.RESULTS The diagnostic sensitivity,specificity,and sensitivity of PCR-reverse point hybrid ization technology for secondary CIN were 70.41%,70.66%,and 0.714,respectively.Sensitivity and specificity for secondary CIN were 752%and 7853%,respectively,the area under the curve value was 0.789.Logistic Multifactorial model analysis revealed that the HPV positive rates and the HPV E6/E7 mRNA positive rates were independent risk factors of CIN grade I(P<0.05).In CIN grade I patients with positive for HPV E6/E7 mRNA,in its orientation to grade CIN patients,in its orientation to grade CIN patients,at 69.2%,compared with patients negative for HPV E6/E7 mRNA(30.8%),significant difference(P<0.05).CONCLUSION HPV E6/E7 mRNA and HPV(PCR-reverse dot hybrid)positive expression have a close relationship with CINgrade disease progression and is an independent risk factor for high-grade CIN lesions.

Subclinical hepatitis E virus genotype 1 infection:The concept of“dynamic human reservoir”

Hepatitis E virus(HEV)is hyperendemic in South Asia and Africa accounting for half of total Global HEV burden.There are eight genotypes of HEV.Among them,the four common ones known to infect humans,genotypes 1 and 2 are prevalent in the developing world and genotypes 3 and 4 are causing challenge in the industrialized world.Asymptomatic HEV viremia in the general population,especially among blood donors,has been reported in the literature worldwide.The clinical implications related to this asymptomatic viremia are unclear and need further exploration.Detection of viremia due to HEV genotype 1 infection,apparently among healthy blood donors is also reported without much knowledge about its infection rate.Similarly,while HEV genotype 3 is known to be transmitted via blood transfusion in humans and has been subjected to screening in many European nations,instances of transmission have also been documented albeit without significant clinical consequences.Epidemiology of HEV genotype 1 in endemic areas often show waxing and waning pattern.Occasional sporadic occurrence of HEV infection interrupted by outbreaks have been frequently seen.In absence of known animal reservoir,where HEV exists in between outbreak is a mystery that needs further exploration.However,occurrence of asymptomatic HEV viremia due to HEV genotype 1 during epidemiologically quiescent period may explain that this phenomenon may act as a dynamic reservoir.Since HEV genotype 1 infection cannot cause chronicity,subclinical transient infection and transmission of virus might be the reason it sustains in interepidemic period.This might be the similar phenomenon with SARS COVID-19 corona virus infection which is circulating worldwide in distinct phases with peaks and plateaus despite vaccination against it.In view of existing evidence,we propose the concept of“Dynamic Human Reservoir.”Quiescent subclinical infection of HEV without any clinical consequences and subsequent transmission may contribute to the existence of the virus in a community.The potential for transmitting HEV infection by asymptomatic HEV infected individuals by fecal shedding of virus has not been reported in literature.This missing link may be a key to Pandora's box in understanding epidemiology of HEV infection in genotype 1 predominant region.

Evaluating the Potential of Nitrofurantoin and Fosfomycin for E.coli UTIs: A Susceptibility Study

This study was designed to find the susceptibility of Nitrofurantoin and Fosfomycin among urinary isolates of Escherichia.coli.Four hundred(400)urine samples were collected for susceptibility of nitrofurantoin and fosfomycin among urinary isolates of E.coli.All indoor and outdoor patients'urinary samples yielded growth of E.coli.Mid-stream urine specimens were inoculated on blood agar and CLED agar and incubated at 35±2°C.Growth was observed,and Escherichia coli was identified by Gram staining,Catalase,Motility test and API 20E(Bio murex)as per standard procedure.Antimicrobial susceptibility testing of isolates for nitrofurantoin and fosfomycin was carried out by the modified Kirby-Bauer disc diffusion method according to CLSI guidelines ATCC 25922.E.coli was used as a quality control strain.A total of 400 samples were tested susceptibility of nitrofurantoin and fosfomycin among urinary isolates of E.coli during this period.A total of 400 samples yielded the growth of E.coli,out of which 178(44.5%)were male and 222(55.5%)were female samples.Among males,18(10%)were tolerant to nitrofurantoin,and 2(1.1%)were tolerant to fosfomycin.Among females,9(4.09%)were susceptible to nitrofurantoin while 6(2.72%)were susceptible to fosfomycin.Among age groups below 45 years old,6(4.76%)were tolerant to nitrofurantoin,and 2(1.58%)were sensitive to fosfomycin.Between 46-66 years old,4(2.81%)were sensitive to nitrofurantoin,and 3(2.11%)were sensitive to fosfomycin.Between 67-90 years old,17(12.87%)were sensitive to nitrofurantoin,and 4(3.03%)were tolerant to fosfomycin.Fosfomycin and nitrofurantoin showed good susceptibility in urinary isolates of E.coli and can be used empirically in our setup.

Expression of the human era cDNA in E.coli

Objective: To amplify human era (Hera) gene, then express it in E.coli. Methods: Human era gene, after amplified by PCR and identified by sequencing, was inserted into the expression vector pGEX-4T3 in which exogenous gene was controlled by Ptac promoter. The recombinant plasmid pGEX-Hera was transformed into DH5 (and induced with IPTG chemically. Results: The human era gene was amplified and the sequence was correct. When the bacteria with pGEX-Hera was induced, an anticipated 65 000 protein band appeared on SDS-PAGE gel and amounted to 23% of total bacterial protein. Conclusion: The human era gene has been successfully amplified and efficiently expressed in E.coli.

Differential expression of bcl-2 and bax genes during the E.coli-induced apoptosis of human U937 cells

To explore the role of bcl-2 and bax genes in the apoptosis of human U937 cells induced by E.coli, flow cytometry assay with annexinⅤ-FITC/PI double staining was used to determine the condition of apoptosis, and the expressions of mRNA of bcl-2 and bax genes were assayed with RT-PCR. It was found that the apoptosis of human U937 cells could be induced by E.coli at various concentration ratios between cells and bacteria for 30 min in a dose-dependent manner. The apoptotic rates at cell/bacteria ratios of 0, 1∶5, 1∶10, 1∶20, 1∶50 and 1∶100 were 3.16%±0.90%, 9.46%±0.84%, 17.90%±1.41%, 35.59%±3.76%, 38.35%±7.12% and 55.07%±5.82% respectively. Also, there was a tendency of alterations in the expression levels of bcl-2 and bax genes with an increased expression level of bax gene and a reduced expression level of bcl-2 gene. It is concluded that E.coli can induce apoptosis in human U937 cells with a down-regulated expression of Bcl-2 and an up-regulated expression of Bax, and this might be related to the induction of apoptosis of the infected cell.

Genotyping Characteristics of Human Fecal Escherichia coli and Their Association with Multidrug Resistance in Miyun District, Beijing

Objective To explore the genotyping characteristics of human fecal Escherichia coli(E. coli) and the relationships between antibiotic resistance genes(ARGs) and multidrug resistance(MDR) of E. coli in Miyun District, Beijing, an area with high incidence of infectious diarrheal cases but no related data.Methods Over a period of 3 years, 94 E. coli strains were isolated from fecal samples collected from Miyun District Hospital, a surveillance hospital of the National Pathogen Identification Network. The antibiotic susceptibility of the isolates was determined by the broth microdilution method. ARGs,multilocus sequence typing(MLST), and polymorphism trees were analyzed using whole-genome sequencing data(WGS).Results This study revealed that 68.09% of the isolates had MDR, prevalent and distributed in different clades, with a relatively high rate and low pathogenicity. There was no difference in MDR between the diarrheal(49/70) and healthy groups(15/24).Conclusion We developed a random forest(RF) prediction model of TEM.1 + baeR + mphA + mphB +QnrS1 + AAC.3-IId to identify MDR status, highlighting its potential for early resistance identification. The causes of MDR are likely mobile units transmitting the ARGs. In the future, we will continue to strengthen the monitoring of ARGs and MDR, and increase the number of strains to further verify the accuracy of the MDR markers.

2种氟喹诺酮类抗生素与群体感应抑制剂对E.coli的联合毒性效应

抗生素滥用带来严重的细菌耐药性,威胁生态环境和人体健康。群体感应抑制剂(quorum sensing inhibitors,QSIs)作为一种理论上难以引发细菌耐药性的新型潜在抗生素替代品,被建议单独使用或与传统抗生素联合使用。因此,考察抗生素与QSIs联合作用效应及其作用机理对其在环境中可能产生的联合暴露风险评估具有重要的参考意义。以应用较广泛的2种氟喹诺酮类药物氧氟沙星(ofloxacin,OFL)、左氧氟沙星(levofloxacin,LEV)和1种新型抗菌剂群体感应抑制剂4-羟基-2,5-二甲基-3(2H)呋喃酮(4-hydroxy-2,5-dimethyl-3(2H)-furanone,HDMF)为研究对象,运用直接均分法和均匀设计射线法分别设计3个二元和1个三元混合物体系,每个体系包含5条具有不同组分浓度比的射线。应用时间毒性微板分析法测定3种药物及其混合物体系对大肠杆菌(Escherichia coli,E.coli)的毒性,应用拟合归零法分析混合物的毒性相互作用及相互作用强度,采用分子间对接技术来探讨可能存在的作用机理。结果表明,HDMF、OFL、LEV对E.coli均具有浓度、时间依赖毒性,以半数效应浓度负对数为毒性指标,3种药物在同一暴露时间毒性顺序:LEV>OFL>HDMF。3种药物的二元混合物体系相互作用类型有拮抗/协同作用,而三元混合物体系的作用类型为协同作用,且作用类型和强度受混合物组分、暴露时间和浓度影响。氟喹诺酮类药物混合物体系中,因药物竞争结合蛋白点位而呈现出拮抗作用。在氟喹诺酮类药物和QSIs混合体系中,QSIs会破坏细菌的生物膜,使氟喹诺酮类药物更容易接触细菌造成损伤,从而呈现协同作用。但随着暴露时间的延长,氟喹诺酮类药物会对DNA造成损伤进而减少QSIs作用蛋白的产生,呈现出拮抗作用。

Prevalence and Seroprevalence of Non-SARS Human Coronaviruses 229E and OC43 in East Tyrol/Austria

The recent SARS-CoV-2 pandemic renewed interest in other previously discovered human coronaviruses—the non-severe acute respiratory syndrome human coronavirus (non-SARS hCoVs) and this study is a starting point for a closer investigation of those. With the pandemic behind us we believe it to be important to also examine the current and past respiratory pathogen landscape in the patient population in our care. Therefore, 954 nasopharyngeal swabs of patients with respiratory diseases collected between October 2018 and March 2020 were tested against the pathogens Mycoplasma pneumoniae, Bordetella pertussis, Influenza A and virus, Human metapneumovirus, respiratory syncytial virus, Parainfluenza virus, human Adenovirus and Polyoma virus BK/JC. Swabs negative against these pathogens were further tested for OC43 and 229E by RT-qPCR. Human coronaviruses 229E and OC43 were proven as the causative agents in a considerable number of cases, confirmed by PCR. Overall, our results show that those two non-SARS hCoVs were responsible for 13.9% (11 of 79) of infections with flu-like symptoms of unknown etiology in the study area. In the subsequent seroprevalence study, it was shown that the seroprevalence rate of IgG antibodies against 229E and OC43 was over 50%, indicating that a big part of the population in our study area has been in contact with these non-SARS-CoVs and has built the specific humoral immune response accordingly.

跨境电商改革与出口企业数字技术创新——基于跨境电子商务综合试验区的准自然实验

跨境电子商务综合试验区建设是我国积极推进制度型开放的重要举措,税费优惠和管理服务完善等跨境电商改革不仅能够激励外贸增长,还会对出口企业产生成本降低效应、人力资本提升效应和内部治理优化效应等积极影响,从而促进出口企业的数字技术创新。将跨境电子商务综合试验区建设作为一项准自然实验,采用沪深A股出口企业2007—2020年的数据,运用多期双重差分模型分析发现:跨境电子商务综合试验区建设(跨境电商改革)显著促进了试验区出口企业的数字技术发明专利增长,跨境电商改革可以通过降低融资成本和经营成本、提高技术人员占比和高学历人才占比、提升公司治理水平和内部控制质量等路径促进出口企业的数字技术创新,跨境电商改革对融资约束程度较高、地区人力资源丰富、ESG表现较差、环境不确定性较强的出口企业具有更为显著的数字技术创新促进作用。应持续推进和不断深化跨境电商改革,并充分发挥制度型开放对企业创新发展的激励作用。

血清人软骨糖蛋白-39、可溶性E-选择素与儿童湿疹及严重程度的相关性

目的探究血清人软骨糖蛋白-39(YKL-40)、可溶性E-选择素(E-selectin)与儿童湿疹的相关性及与湿疹严重程度的关系。方法选取2019年3月至2020年3月延安大学附属医院收治的湿疹病儿120例为观察组,根据湿疹面积及严重程度指数(EASI)评分将病儿分为轻度组(42例)、中度组(40例)和重度组(38例)。选取同期进行体检者50例作为对照组。检测血清YKL-40、E-selectin水平;比较临床资料;采用Pearson法分析观察组YKL-40、E-selectin水平的相关性;Spearman法分析血清YKL-40、E-selectin水平与病情严重程度的相关性;logistic分析发生重度湿疹的影响因素。结果观察组年龄和性别与对照组比较均差异无统计学意义(P>0.05),而观察组病儿在过敏性鼻炎[18.33%(32/120)]、过敏史[65.00%(78/120)]、糖尿病家族史[57.50%(69/120)]、YKL-40[(38.05±4.80)g/L]和E-selectin水平[(64.12±6.83)μg/L]上与对照组[10.00%(6/50)、28.00%(14/50)、38.00%(19/50)、(24.69±3.44)g/L、(56.38±6.18)μg/L]差异有统计学意义(t/χ^(2)=4.37、19.46、5.38、17.85、6.92,P<0.05);轻度组、中度组和重度组的YKL-40[(30.95±3.51)g/L、(38.28±4.69)g/L、(45.66±6.34)g/L]和E-selectin水平[(58.82±6.05)μg/L、(63.96±6.85)μg/L、(70.15±7.68)μg/L]均依次显著升高,差异有统计学意义(F=88.67、26.71,P<0.05);观察组血清YKL-40、E-selectin呈正相关(r=0.68,P=0.001);血清YKL-40、E-selectin与病情严重程度呈正相关(r=0.68、0.58,均P<0.001);过敏史、糖尿病家族史、YKL-40和E-selectin为患湿疹严重程度的独立危险因素(P<0.05)。结论血清YKL-40和E-selectin水平升高,湿疹病儿病情可能会加重,二者均为湿疹严重程度的独立危险因素。

人机协同装配多目标检测的改进YOLOv7算法

针对人机协同装配环境复杂多变且装配零件尺度差异大、部分零件相似度高的特征,为保证人机协作装配过程中机器人准确抓取装配零件,提出了一种改进的YOLOv7模型来提高装配场景中多零件目标检测效果。首先,采用ODConv(Omni-dimensional dynamic convolution)替换YOLOv7主干网络中的卷积层,使其能够自适应调整卷积核的权值,提取不同形状、大小的装配零件的特征。其次,在YOLOv7主干网络中引入SimAM(Selective image attention mechanism)模块来减轻复杂多变的装配环境背景对零件检测准确率的影响。最后,使用Efficient-IOU替换原始的CompleteIOU来加速收敛,同时降低部分装配零件相似度高对检测准确率的影响。实验结果表明,该模型的平均准确率为93.4%,改进后的网络优于原始网络和其他目标检测算法。所提出的改进YOLOv7算法在保持高精度的同时具有较高的FPS,模型参数和计算量也相对较低,适合动态人机协同装配场景下实时目标检测要求。

重组E.coli工程菌高密度培养生产人源型胶原蛋白

Several technical parameters were studied during the fermentation of recombinant E.coli for the production of collagen-like biopolymer.The effects of dissolved oxygen as well as glucose concentration on fermentation were observed.The OD 600 value could reach 98 when dissolved oxygen was controlled at 50% and glucose around 1%.The production of human-like collagen with a yield of 29.4% was obtained.

rhEGF联合利多卡因与维生素E治疗儿童复发性口腔溃疡的效果

目的探讨重组人表皮生长因子(rhEGF)联合利多卡因与维生素E治疗儿童复发性口腔溃疡(ROU)的临床效果.方法选取2022年7月—2023年6月期间南阳医学高等专科学校第一附属医院口腔科收治的94例ROU患儿为研究对象,采用随机数字表法分为对照组及观察组,每组47例.对照组采用维生素E联合利多卡因治疗,观察组在此基础上采用rhEGF治疗.比较两组患儿的症状改善情况、疼痛评分、溃疡面积、炎症指标及总有效率.结果观察组的疼痛缓解时间、溃疡愈合时间、进食改善时间分别为(3.16±1.06)d,(4.37±0.92)d,(3.49±1.04)d,均短于对照组,组间差异有统计学意义(P﹤0.05).治疗3d后,观察组的疼痛评分、白细胞介素-8、肿瘤坏死因子-α水平均低于对照组,溃疡面积小于对照组,组间差异有统计学意义(P﹤0.05).观察组的治疗总有效率为97.87%,高于对照组的82.98%,差异有统计学意义(P﹤0.05).两组的用药相关不良反应总发生率比较,差异无统计学意义(P﹥0.05).结论采用rhEGF联合利多卡因与维生素E治疗儿童ROU的效果理想,能促进临床症状消退,降低患儿炎症指标水平,且在加速溃疡愈合及改善其口腔状况方面也有积极作用.

养殖场空气中E.coli磺胺类抗生素的抗性

本文从养殖场空气中分离出360株E.coli(大肠杆菌,Escherichia coli),应用肉汤微量稀释法和PCR方法,分离磺胺甲唑敏感菌株,检测抗生素抗性和抗性基因.在分离的E.coli中,对磺胺甲唑敏感菌株为95株(26.4%),有48株含有青霉素、氯霉素、四环素、环丙沙星、庆大霉素和利福平的抗性,而47株未含有抗性.其中,7株菌株含有1种抗生素抗性、11株菌株含有2种抗生素抗性、17株菌株含有3种抗生素抗性、6株菌株含有4种抗生素抗性、4株菌株含有5种抗生素抗性、3株菌株含有6种抗生素抗性.对抗生素的耐受能力依次为:氯霉素、青霉素、四环素、环丙沙星、庆大霉素、利福平.磺胺甲唑敏感菌株共检出163个抗性基因,sul1、int1、sul2、Int2、sul3检出数量依次为49、44、29、20和19;含一种、二种、三种、四种、五种抗性基因菌株分别为45、22、10、7、2;但有6株未检测出抗性基因.结果表明养殖场建场时间、抗生素使用、养殖规模等与抗生素抗性菌的抗性呈正相关;养殖场空气中分离的E.coli抗生素抗性较高,且具有多重抗性;抗生素抗性的表现型与其基因型之间出现不完全吻合现象.

秦皇岛地区狐源致病性E.coli对四环素类药物耐药性和耐药基因的检测

为了确定秦皇岛地区狐源大肠杆菌(E.coli)对四环素类药物的耐药性和耐药基因分布,采用常规的鉴定方法,从不同养狐场送检的腹泻的狐狸体内分离鉴定出20株E.coli。致病性试验表明,该菌为致病性E.coli。药敏试验结果表明:分离菌株对四环素和强力霉素药率分别达到95%和90%。通过PCR方法检测分离菌株四环素类药物的耐药基因,结果显示,tet A和tet B基因的检出率分别为100%和95%。本研究为秦皇岛地区防治狐源致病性大肠杆菌病提供实验基础。

中药三黄汤、小檗碱对E.coli生长抑制作用与庆大霉素的比较

庆大霉素对E .coli的抑菌作用强 ,试管稀释法、琼脂稀释法和平板抑菌圈法抑菌试验得到一致的MIC(3～5 μg/mL) ;三黄汤、小檗碱抑菌作用弱而稳定 ,试管稀释法测得的MIC分别为 5 0 0mg/mL和 2 .5mg/mL ,而用平板抑菌圈法得不到明显的抑菌圈 .在亚MIC药物液体分批培养时 ,庆大霉素抑菌曲线起初 2h迅速下降 ,而后回升到初始浓度 ,而三黄汤抑菌曲线平缓稳定 ,说明中药和抗生素的抑菌机制明显不同 .庆大霉素与小檗碱混合使用时 ,与庆大霉素单独使用相近 ,而与三黄混合使用时 ,则主要表现三黄汤的抑菌作用 .因此中西药结合时需要慎用 .在接近MIC药物培养基中连续传代 2 0次后 ,庆大霉素MIC提高 8倍多 ,而三黄汤和小檗碱MIC无显著变化 ,无抗药性产生 ,也不产生对庆大霉素的交叉抗药性 .研究结果还表明 ,在 1/ 4MIC三黄汤中连续传代 2 0次 ,能消除E .coli已形成的庆大霉素抗性 ,这为解决抗生素抗药性提供了线索 .图 4参 2

来自腹泻合并急性肾衰病人疫区的99株E.coli O157∶H7的鉴定结果分析

目的调查研究河南省2000年3月17日-7月6日发生的腹泻合并急性肾衰病人的致病菌。方法采集病人、外环境、家畜和家禽标本620份,采用免疫磁珠集菌法、CHROMAGAR-O157∶H7显色培养基分离及营养肉汤增菌、rfbO157、rfbO111引物多重PCR扩增等方法进行病原菌的检测。结果分离出99份E.coli O157∶H7菌株,其中rfbO157、志贺氏样毒素2(stx2)、溶血素(hlyA)、肠上皮细胞纤毛消除素(eaeA)基因和vero细胞毒性试验均阳性的有56株,其它基因组合7株,36株无毒力基因。结论99株E.coli O157∶H7在CHROMAGAR-O157∶H7显色培养基生长形态、颜色,生化反应及毒力基因表现等方面出现多样化,对于今后在制定对该菌的诊断标准、传染源的控制及细菌毒力学等方面的研究提供了依据。