Characteristics of β-Lactamase Synthesis in E. coli and K. pneumanie Strains in Nosocomial Infections

Background: Recently micro-organisms that synthesize extended-spectrum β-lactamase (ESBLs) were increased. The peculiarities of ESBL synthesis of Escherichia coli and Klebsiella pneumoniae strains that cause nosocomial urinary tract infections, surgical site infections and pneumonia in surgical clinic were studied. ESBL synthesis were observed 38.9% of E. coli strains obtained from urine, 92.3% of strains obtained from surgical site infections, and 50% of strains obtained from sputum. ESBL synthesis were observed 37.5% of K. pneumoniae strains obtained from urine, 85.7% of strains obtained from surgical site infections, and 60% of strains obtained from sputum. Different levels of ESBL synthesize of E. coli and K. pneumoniae strains isolated from different pattern is discussed. Conclusion. ESBL synthesis is common in E. coli and K. pneumoniae strains, which cause nosocomial infections. The frequency of occurrence of ESBL s synthesis among of these strains depends on clinical forms of nosocomial infections.

The Transport and Persistence of Escherichia coli in Leachate from Poultry Litter Amended Soils

Fecal coliform bacteria such as Escherichia coli (E. coli) are one of the main sources of groundwater pollution. An assessment of the transport and Persistence of E. coli in poultry litter amended Decatur silty Clay soil and Hartsells Sandy soil was conducted using soil columns and simulated groundwater leaching. Enumeration of initial E. coli was determined to range from 2.851 × 103 to 3.044 × 103 CFU per gram of soil. These results have been used in a batch study to determine the persistence rate of E. coli in Decatur silty Clay soil and Hartsells Sandy soil. Results prove that E. coli survival growth rate increases for clay soil later than and at a higher rate than sandy soil. The column study has determined that E. coli was transported at a rate of 3.7 × 106 CFU for Decatur silty loam and 6.3 × 106 CFU for Hartsells sandy per gram of soil. Further, linear regression analysis predictions show higher porosity and soil moisture content affect transport, and Hartsells sandy soil has higher transport of E. coli due to its higher porosity and lower volumetric water content.

Growth Inhibition of Escherichia coli and Staphylococcus epidermidis from Various Types of Honey

Honey has long been considered a wound treatment used to keep cuts and other epidermal injuries clean. This study tested that claim by comparing manuka honey used in medicine today, local unprocessed honey taken straight from a hive, and pasteurized honey found at a store, on strains of E. coli and S. epidermidis. The study evaluated the effects these honeys had on bacterial growth to determine which had the greatest inhibition of bacterial growth. To determine this, plates streaked with strains of E. coli or S. epidermidis bacteria and agar wells filled with one of the honeys were incubated and subsequently the diameter of the zone of inhibition was measured. After 20 trials using each honey and bacteria type, manuka and unprocessed were shown to have a statistically significant advantage over the pasteurized honey at inhibiting the growth of E. coli and S. epidermidis, though it was variable whether manuka had an advantage over the unprocessed honey.

Evidence and Potential Antibacterial Mechanism of Chinese Traditional Medicine Compounds for the Development of E. coli

Astragalus membranaceus (huangqi), Allium sativum (garlic), Cinnamomum cassia (cinnamon), and Dolichos lablab L. (white hyacinth bean) are the traditional Chinese herbs that were used in prescriptions in treating diarrhea caused by bacterial infection. These herbs are relatively safe for use and investigation. This study aimed to investigate the effects of Astragalus membranaceus, Allium sativum, Cinnamomum cassia, and Dolichos lablab L. on the metabolism of Escherichia coli (E. coli). The growth rate of E. coli was monitored under the influence of each herb, revealing that Astragalus membranaceus and Allium sativum exhibited significant antibacterial activity, whereas Cinnamomum cassia and Dolichos lablab L. demonstrated moderate inhibitory effects on E. coli growth. Further inhibition zone testing allowed for the evaluation of each herb’s potency and the number of generations required for E. coli to develop resistance. Additionally, the impact of the four herbs on the expression of outer membrane protein A (OmpA) in E. coli was examined by using qPCR. The findings revealed that Astragalus membranaceus acted as a sustainable bactericide by inhibiting the growth and metabolism of E. coli MG1655 through the suppression of OmpA expression. These results suggest that Astragalus membranaceus has potential as a natural antimicrobial agent for treating E. coli infections.

Escherichia coli Pathotypes in Children with Acute Diarrhea in an Informal Settlement in Nairobi, Kenya

Diarrhea is among the leading causes of morbidity and mortality in children aged Escherichia coli (DEC) accounts for 30% - 40% of childhood diarrhea cases. To identify the pathotypes involved in diarrheal outbreaks in Kenya, we analyzed archived E. coli isolates from children E. coli confirmation and antimicrobial susceptibility testing were done using the VITEK®2 instrument. Pathotype identification was performed via conventional polymerase chain reaction. Of 175 E. coli isolates, 48 (27%) were DEC pathotypes, with enteroaggregative E. coli (EAEC) predominating (71%, 34/48). Enterohemorrhagic (EHEC) and enteropathogenic E. coli (EPEC) represented 19% and 10% of isolates, respectively. Enteroinvasive and enterotoxigenic pathotypes were not identified. All DEC isolates were susceptible to amikacin, ertapenem, imipenem, meropenem and tigecycline. Conversely, most (>80%) isolates were resistant to ampicillin, ampicillin-sulbactam and sulfamethoxazole-trimethoprim. Half of all EAEC and EPEC strains were resistant to cefazolin while half of EHEC isolates were resistant to ciprofloxacin and moxifloxacin. In total, 18 resistance phenotypes were identified with “ampicillin-cefazolin-ampicillin/ sulbactam-sulfamethoxazole/trimethoprim” predominating (33%, 16/48). The majority (81%) of DEC isolates were multidrug-resistant, with extended-spectrum beta-lactamase production identified in 8% of these isolates. This study highlights the predominance of Enteroaggregative E. coli and multidrug resistance of DEC pathotypes. Studying the epidemiology of diarrheal disease and antimicrobial resistance surveillance, will aid in identifying dominant etiological agents of diarrhea and newly emerging resistant strains in informal settlements.

Detection of aac(3)IIc, aac(6)Ib, armA Genes Coding for Escherichia coli Resistance to Aminoglycosides in Burkina Faso

Background and Prupose: Antibiotic resistance is a major global health concern. In addition to the existing data on the prevalence of bacterial resistance to antibiotics, there are patchy data on bacterial resistance to aminoglycosides in Burkina Faso. In this study, we determined the prevalence of aminoglycoside resistance genes in E. coli, including aac(3)-IIc, aac(6)-Ib and armA in Ouagadougou, and determined which antibiotics in this class are most affected by resistance. Material and Methods: This study was conducted on 216 E. coli strains collected from the biomedical analysis laboratories of Saint Camille and Schiphra hospitals. E. coli strains were isolated from pus and urine samples collected between September 2018 and January 2019. Antibiotic susceptibility testing was performed using aminoglycosides, β-lactams, fluoroquinolones, and sulfonamides. Aminoglycoside resistance genes were detected in strains with at least one aminoglycoside resistance gene using conventional/multiplex PCR. Results: Aminoglycoside resistance was observed in 46.8% (101/216) of strains. The resistance rates were respectively 45.37% for Tobramycin, 32.40% for Gentamicin, 14.81% for Kanamycin, 2.31% for Netilmicin, 1.84% for Neomycin, and 0.46% for Amikacin. PCR showed that 86 strains (85.15%) possessed the aac(3)-IIc gene, 71 strains or 70.30%) possessed the aac(6’)-Ib gene, and nine strains (8.91%) possessed the armA gene. Conclusion: Aminoglycoside resistance in pathogenic E. coli strains is mainly due to the presence of the aac(3’)-IIc and aac(6’)-Ib genes. The presence of armA was first reported in Burkina Faso. Netilmicin, Neomycin and Amikacin are good therapeutic options for treating urinary tract and pus-forming infections.

De Novo Synthesis of Biopaint Using Transformed Bacteria: Analysis of Spectral Intensity Trends and Comparison to Commercial Paint

Background: Commercial paint pigments contain toxic heavy metals that harm humans and pollute the environment. To mitigate these harms, ecologically safe pigments are necessary. Objective: This experiment aims to create a biopaint de-novo using transformed Escherichia coli bacteria and compare it to commercial paint. Methods: Genetically engineered E. coli bacteria producing magenta pigment were grown in petri dishes. The pigment protein was extracted, filtered, and dehydrated into a crystalline powder. This was mixed with acrylic medium to make biopaint. The biopaint and commercial paint were applied on acrylic paper;red, green, blue, and total spectral intensities were measured daily under different testing conditions. Spectral intensity variability was measured and compared using the Coefficient of Variation (CV). Trends in spectral intensity were analyzed using regression analysis. Results: The differences in the CV of biopaint to commercial paint were less than 20% under all testing conditions. Spectral intensities for both biopaint and commercial paint did not show any significant change during the testing period under the conditions of room temperature, heat, and humidity. However, under the cold testing condition, biopaint showed a slight but statistically significant (p-value Conclusion: This experiment proves that E. coli-derived pigments can be used to make biopaint which has a similar durability to commercial paint as measured by the spectral intensities.

免疫磁分离技术在E.coli O157∶H7检测中的应用

免疫磁分离(i mmunomagnetic separation)技术因其具有选择性好、特异性强、能起到浓缩的作用,已与其他快速检测方法如电化学、光学等方法连用,应用于食品、环境卫生检测等领域。免疫磁分离技术是目前最有推广价值的技术之一。文章通过比较不同的E.coli O157∶H7-免疫磁珠(immunomagnetic beads,I MB)浓度配比、E.coli O157∶H7与Bacillus subtilis不同的体积比下的免疫磁分离的捕获率,得出当E.coli O157∶H7-I MB浓度配比为1∶30时,捕获率近100%,即所有的目标菌均可被捕获到;在总体积不变、IMB的加入量一定的情况下,随着Bacillus subtilis比例的增加,捕获率出现先下降后上升的情况。同时,将IMS与ATP生物发光法结合起来,对不同浓度的E.coliO157∶H7进行了检测,得出该方法与传统的平板培养法具有很好的线性相关性,则R2=0.9882,检测限可低达102CFU.mL-1。

嗜鞣管囊酵母(Pachysolen tannophilus 1622)和重组大肠杆菌(E．coli(pGM-PA))乙醇发酵特性研究

通过对嗜鞣管囊酵母和重组大肠杆菌代谢木糖及混合糖产乙醇研究,阐明两种菌的不同发酵能力。结果表明:重组大肠杆菌在5%木糖培养基中乙醇产率为理论值的100%,在10%木糖的培养基中乙醇产率达到理论值的96%。重组大肠杆菌木糖转化乙醇的能力明显高于嗜鞣管囊酵母,但嗜鞣管囊酵母与重组大肠杆菌相比乙醇耐受度更高(可达8%).且代谢过程中pH降低幅度不大。固定化技术对于提高P.tannophilus 1622乙醇发酵表现作用显著,而对重组大肠杆菌乙醇发酵的产率提高没有明显作用。

猪卵透明带-3β融合蛋白在E.coli中的表达和鉴定

对全长猪卵透明带－３β（ｐＺＰ３β）ｃＤＮＡ的５端重新测序分析，发现文献报道的该克隆基因５端非编码序列中漏读了两个碱基，继而选择符合ｐＺＰ３βｃＤＮＡ阅读框的ｐＷＲ４５０－２载体质粒，通过双酶切构建了β－半乳糖苷酶／ｐＺＰ３β融合蛋白基因的细菌表达质粒。转化宿主菌后用ＩＰＴＧ诱导，ＳＤＳ－ＰＡＧＥ分析表明ｐＺＰ３β融合蛋白在Ｅ．ｃｏｌｉ中获得表达，并在蛋白印迹鉴定中能同兔抗猪ＺＰＩｇＧ呈特异性免疫反应。

单味中药水提物对鸡源耐药性E.coli地方株的体外抑菌活性研究

为了研究单味中药水提物对河北地区鸡源耐药性大肠埃希氏菌(Escherichia coli,E.coli)地方流行株QH15(O_2)、QH16(O_(38))、QH17(O_(89))的体外抑菌活性。利用平板琼脂打孔法和改良微量二倍稀释法分别测定抑菌圈直径和最小抑菌浓度(MIC)。结果表明:诃子、五味子、五倍子、黄连、黄芩、苦参6种中药均对3株鸡耐药性E.coli地方株高度敏感,抑菌圈直径在15~24 mm之间,MIC在7.825 mg/mL^31.25 mg/mL之间,其他的药物存在不同程度的敏感性。

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。

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。

正交试验优化培养基因工程菌(E.coli pGEX)产降血压肽培养基的组成

通过正交试验进行摇瓶发酵,确定该菌株融合蛋白表达的最佳培养基配方,其各成分质量分数为:胰蛋白胨2.6%,酵母提取物1.9%,氯化钠0.5%,葡萄糖0.5%,另外KC l 4 mmol.L-1,MgC l210 mmol.L-1。在适宜的发酵条件下,使用优化培养基可使GST融合蛋白的表达量达到1.8 g.L-1,占总蛋白的25%。

过量表达苹果酸酶对E.coli脂肪酸合成能力的影响

为了考察苹果酸酶对原核生物脂肪酸合成能力的影响,本研究从E.coliK-12中克隆了苹果酸酶基因(NADPME,EC1.1.1.40)MaeB,并插入质粒pET30a-T,构建了重组质粒pMX20,经IPTG诱导在E.coli BL2(IDE3)获得了大量表达。摇瓶发酵结果表明,过量表达苹果酸酶基因会改变大肠杆菌脂肪酸合成能力,并在添加适宜底物苹果酸(15mmol/L)时,胞内总酯含量比受体菌提高了4倍,约197.74mg/g,产率为1.89%。本研究为脂肪酸生产提供了优良菌株,具有一定的应用开发前景。

中国白兔白介素-15基因的克隆、序列分析及其在E.coli中的表达

以RT-PCR技术对用ConA刺激的中国白兔外周血淋巴细胞（PMBCr）进行扩增,将纯化后的PCR产物克隆入pMD18-T中进行核苷酸序列测定,并与不同物种的IL-15基因进行序列比较。结果IL-15基因全长489 bp,编码162个氨基酸,其中前29个氨基酸残基构成信号肽序列。与不同物种IL-15基因相比,核苷酸和推导的氨基酸序列有一定的差异。在推导的中国白兔IL-15氨基酸序列中,在108～110、119～121、127～129和143～146位存在4个潜在的N-联糖基化位点,同时存在6个Cys残基。将pTIL-15双酶切,回收目的基因片段克隆到大肠杆菌表达载体pET28a中构建了重组质粒pETIL-15,转化大肠杆菌BL21（DE3）,并用IPTG进行了诱导。结果重组菌菌体裂解物经SDS-PAGE电泳可检测到相对分子质量为20 500的重组目的蛋白。经凝胶薄层扫描,目的蛋白表达量可占菌体蛋白的13.6%。

E·coli木糖异构酶基因的克隆及表达条件的优化

采用PCR技术以大肠杆菌JM109基因组DNA为模板扩增得到木糖异构酶基因xylA,连接到载体pET-22b(+),得到重组质粒pET-22b(+)-xylA。将此重组质粒转化到大肠杆菌菌株BL21(DE3)中,重组菌株经IPTG诱导后,通过半胱氨酸-咔唑法测得木糖异构酶活力。每mL发酵液中重组菌株显示出酶活力约为0.84 U。SDS-PAGE电泳结果显示出明显的5×104(相对分子质量)特异性蛋白质条带。

E·coli L-天冬酰胺酶B细胞抗原表位氨基酸残基Lys^(196)对其抗原性的影响

目的:研究重组E.coli L-天冬酰胺酶B细胞抗原表位中关键氨基酸残基对其抗原性的影响。方法:以Ala为替代残基,对抗原表位192TPARKHTS199中Lys196进行PCR定点突变,双向免疫扩散法和间接ELISA法分析新型重组E.coli L-天冬酰胺酶的抗原性。结果:采用双向免疫扩散法和间接ELISA法检测,与重组E.coli L-天冬酰胺酶相比,新型重组E.coliL-天冬酰胺酶与重组E.coli L-天冬酰胺酶抗体结合率下降64%。结论:通过对重组E.coli L-天冬酰胺酶B细胞抗原表位关键残基的定点突变有效地降低了其抗原性。

内源性血管生成抑制因子A rresten在E.coli JM109中的表达及抗新生血管生成的药理学研究

目的构建内源性血管生成抑制因子Arresten基因的原核表达载体，并进行表达，抑制新生血管的药理学实验中发现，该表达产物具有抑制鸡胚绒毛尿囊膜血管生长的功能。方法从健康产妇的胎盘组织中提取总RNA，经逆转录-聚合酶链式反应（RT-PCR）扩增出Arresten基因，构建重组质粒pBV220-Art转化E．coli JM109进行原核表达，大量表达提取Arresten蛋白，用鸡胚绒毛尿囊膜实验进行活性测定。结果成功构建的重组质粒pBV220-Arr在E．coli JM109菌株中2～8h均可获得表达，其中诱导4h表达效率最高，Arresten蛋白可明显抑制鸡胚绒毛尿囊膜血管生长，活性功能明显强于血管抑素。结论成功构建Arresten基因重组质粒pBV220-Arr，并可在E．coli JM109菌株中获得表达，Arresten蛋白具有明显的抑制血管生成的作用。

动物源E.coli O157:H7 stx基因的检测与系统进化分析

为了解2009-2010年间在河南、甘肃地区分离鉴定的5株大肠埃希菌O157(E.coli O157)携带stx的情况及不同分离株间stx分子进化与变迁的情况,本研究利用PCR方法对分离株进行了stx基因检测,并完成了序列测定与系统演化分析。结果表明,5株不同动物源的分离株均含有stx1及stx2基因。序列分析结果显示5株分离株间stx1、stx2的核苷酸及氨基酸同源性均较高;stx1基因均与参考株中的山羊源和食品源E.coli O157菌株的同源性较高,进化树中遗传距离最近;分离株的stx2基因与多株牛源及少数人源参考株也具有较高的同源性,进化树中虽然5株分离菌均在一个大主干分支中,但分离株27与其他各分离株及参照株遗传距离最远,独自处于一次级分支中;分离株L37与W、12与50分别分布于牛源、人源E.coli O157小次级分支中;由此可推测,分离株所携带的stx1很有可能是经食品源或羊源E.coli O157传递而来;分离株L37与W、分离株12与50的stx2可能是由牛源、人源E.coli O157菌株传递而来,分离株27的stx2来源不清楚。研究结果表明,5株E.coli O157分离株均含有stx1、stx2基因,但两个基因的起源存在差异。