Performance Parameters:Demobilization Antibiotic Resistant Bacteria(ARB)and Carrying Genes(ARG)in Wastewater Disinfection

The UV irradiation is used for removing Antibiotic Resistant Bacteria(ARB)and Antibiotic Resistance Genes(ARG)from wastewater treatment.Bacteriophages are viruses that infect within bacteria,are recognized for bacterial control.The influence of some parameters in quantification and performance influencing of pathogen demobilization could be considered in disinfection of wastewater.The comparison of Polyvalent phage(NE1)versus Coliphage(NE4)in suppressing a bacterium Escherichia coli(NDM-1:b-lactam-resistant)with UV irradiation was observed the efficacy in reduction of cells in the disinfection and parameter process.The results with the effect of UV-C irradiation on NDM-1 infected with 1%of NE4 showed a decrease of cells from 8×10^(6)to 2×10^(5)in 60 min with UV-C dose.The NDM1(E.coli)was infected with 1%of NE4(Polyvalent Phage)under magnetic stirring for 1 h,the cells count was 8×10^(6).After 1 h in UV-C e×posure,the cells number reached 3×10^(5).The NDM1 that was e×posed in 1 h of UV-C irradiation and then was infected with 1%of NE4.Cells counting were done 24 h after this procedure.These cells were e×posed in UV-C and showed a reduction in the number of cells from 1×10^(8)to 4×10^(5)after 60 min.The results indicate that bacteriophages can mitigate bacteria species,and combined the conventional water disinfection technologies that can support the microbial safety control strategies.

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.

Detection of new antibiotic resistance gene profile in Escherichia coliassociated with avian leukosis virus infection from broiler chickens

The Escherichia coli(E.coli)is prevailing worldwide,but the epidemiology of E.coli infections feature regional distribution characteristics to some extent.E.coli,as a zoonotic pathogen,can be transferred from animals to humans through food chain or via contact with wounds,causing a public health risk.We reported the swelling of proventriculus and tracheal bleeding following the death in two broiler chickens(Gallus gallus domesticus)from Beijing,China.To investigate whether a virus was involved in the infection,Madin Darby Bovine Kidney(MDCK)cells were co-cultured with supernatants of proventriculus,trachea and spleen homogenates.The avian leucosis virus was detected in the samples of proventriculus and trachea,but the avian influenza virus,the Newcastle disease virus and the avian infectious laryngotracheitis virus were not detected.E.coli isolates were resistant to almost all the antimicrobial as tested except for the combinations of amoxicillin/clavulanic acid and sulfamethoxazole/trimethoprim.PCR tests demonstrated the presence of antibiotic resistance genes in these E.coli isolates and further research revealed a novel gene profile with the presence of CTX-M-1,gyrA,gyrB,oqxA,oqxB,parC and Sul2 antibiotic resistance genes in a strain isolated from a proventriculus sample.These results demonstrated that the presence of antibiotic resistant E.coli would not necessarily cause outbreak of large-scale disease.However,when the bacteria carrying new antibiotic resistance genes enter the environment,it may result in the development of more virulent strains which will potentially impact human and animal health.

<i>Escherichia coli</i>Harbouring Resistance Genes, Virulence Genes and Integron 1 Isolated from Athi River in Kenya

Rivers can act as reservoirs of highly resistant strains and facilitate the dissemination of resistance, virulence and integron 1 genes. A cross-sectional study was carried out where 318 water samples were collected (53 from each site) and from the samples, 318 E. coli isolates were analysed for resistance genes, virulence genes and integron 1 using Polymerase Chain Reaction. 22% of the isolates had blaTEM, 33% had blaCTX-M and 28% had blaCMY. Prevalence of typical Enteropathogenic E. coli strains (carrying both eae and bfp genes) was 5% while the prevalence of atypical Enteropathogenic E. coli (carying only eae) was 1.8%. The prevalence of Enteroaggregative E. coli carrying the aggr genes was 11%. The prevalence of Enterotoxigenic E. coli encoding only lt toxin was 16 (5%) and while those carrying only st toxin was 6.9%. The prevalence of Enteroinvasive E. coli strains encoding as IpaH was 5% while that of strains, adherent invasive E. coli, carrying adherent invasive gene inv was 8.7%. 36% isolates were positive for class 1 integrons which were mostly isolated near the sewage effluent from waste treatment plant. Anthropogenic activities and close proximity to sewage treatment plant were found to play a key role in pollution of water body and accumulation of resistance and virulence genes. These results suggest that waste treatment plant may act as reservoir of resistance, virulence and integron 1 genes and is a potential risk to human and animal health in the region.

Presence of Virulence-Associated Genes and Ability to Form Biofilm among Clinical Isolates of <i>Escherichia coli</i>Causing Urinary Infection in Domestic Animals

Background: Urinary tract infection caused by Escherichia coli is a frequently observed condition both in humans and animals. Uropathogenic E. coli (UPEC) has been shown to have a pathogenicity island that enables them to infect the urinary tract. Because there is little information about the presence of UPEC-associated virulent genes in animal isolates this work was carried out with the intent to enhance the understanding about the strains of E.coli that cause infections in animals. Results: We screened 21 E. coli strains isolated causing urinary tract infection in domestic animals. Primers were designed to amplify urinary infection-associated genes. Nine genes, papA, tcpC, fyuA, tpbA, Lma, hylA, picU, tonB, and flicC were then amplified and sequenced. Different from the human isolate CFT073, all the animals E. coli lack some of the pathogenesis-associated genes. Genes encoding for proteins used to scavenge iron appear not to be so necessary during animal infections as they are in human infection. In further investigation of phenotypic properties, it was observed that animal UPECs have significantly more impaired ability to form biofilms than human UPEC strain. Conclusions: This study identified significant differences between human and animal UPECs. This may have its roots in the fact that it is difficult to determine if an animal has symptoms. Future studies will focus on some of the observations.

Clonal Dissemination of Genetically Diverse Fluoroquinolone-Resistant Extended-Spectrum Beta-Lactamase (ESBL)-Producing Escherichia coli ST131 in a Veterans Hospital in Southern Taiwan

Uropathogenic Escherichia coli is the common pathogen to cause urinary tract infections (UTIs) and have become multidrug-resistant (MDR) extended-spectrum β-lactamase (ESBL) producers. The differences in the antimicrobial susceptibility, 5 bla genes, 12 virulence genes of 87 clinical ESBL-producing E. coli isolates and genomic variations and sequence types of 18 recurrent and repeated isolates from 9 patients were investigated. The 87 MDR-ESBL isolates collected mainly from indwelling urinary catheters (IUCs) and UTIs were highly resistant to fluoroquinolones, with over 50% of the isolates being resistant to cefepime and piperacillin/tazobactam and a few being resistant to carbapenem. These isolates carried at least two of the five bla genes examined, with the highest prevalence (87.4%) found for blaCTX-M (blaCTX-M3-like and blaCTX-M14-like), followed by blaCMY-2 (80.5%) and blaSHV (56.3%). The predominant virulence genes were the fimbriae gene fimH and the toxin genes cnf1 and hlyA in blood isolates and the capsule gene kpsMTII in UTI and blood isolates. Over 80% of the isolates carried yersiniabactin and aerobactin of siderophores. In 18 isolates, the fluoroquinolone-resistant ST131 isolate of pulsotypes I and II with blaCTX-M-15 was clonally disseminated in the hospital. The genomic plasticity of these ST131 occurred mainly through the conjugative plasmids with differences in replicon types A/C, I1, FIA, FIB and Y, size and number. In conclusion, MDR ESBL-producing E. coli isolates differed in virulence genes of UPEC and antibiotic resistance associated with the sources. Plasmid acquisition and chromosomal variations increase the spread of fluoroquinolone-resistant UPEC ST131 worldwide.

Antimicrobial Effects of Plant Compounds against Virulent <i>Escherichia coli</i>O157:H7 Strains Containing Shiga Toxin Genes in Laboratory Media and on Romaine Lettuce and Spinach

Escherichia coli strains produce Shiga-toxins Stx-1 and Stx-2 that contribute to their virulence. The objective was to evaluate antimicrobial activities of plant essential oils (oregano, cinnamon, lemongrass), their active components (carvacrol, cinnamaldehyde, citral) and plant-extracts (green tea polyphenols, apple skin, black tea, decaffeinated black tea, grapeseed and pomace extracts) against E. coli O157:H7 strains containing Stx-1 and Stx-2 genes, as determined by Multiplex Polymerase Chain Reaction, in vitro and on leafy greens. Antimicrobials at various concentrations in sterile PBS were added to bacterial cultures (~3 - 4 logs CFU/ml), mixed thoroughly, and incubated at 37°C. Surviving bacteria were enumerated at 0, 1, 3, 5 and 24 h. The most effective essential oil (oregano oil;0.5%) and plant extract (green tea;3%) were evaluated against E. coli O157:H7 on romaine lettuce and spinach stored at 4°C for 7 days. Microbial survival was a function of the concentration of antimicrobials and incubation times. All antimicrobials reduced bacterial population to below detection levels in vitro;however, essential oils and active components exhibited greater activity than plant extracts. Oregano oil and green tea reduced E. coli O157:H7 on lettuce and spinach to below detection. Plant-based antimicrobials have the potential to protect foods against E. coli O157:

The Truncated Gene cfaD′ Positively Regulates CFA/Ⅰ Expression of Enterotoxigenic Escherichia coli

The gene cluster cfaABCED’ of enterotoxigenic Escherichia coli, encoding the fimbriae which is called colonization factor antigen located on a plasmid. It is positively regulated by cfaR, a member of the AraC family, and the cfaD’ gene region, which is located downstream of cfaE and is homologous to cfaR, had been described as a truncated cryptic gene. In the present study we observed that the CFA/ fimbriae subunit, cfaB, was expressed in lower amount by the cfaABCED’ clone pNTP513 in host E. coli HB101. The expression of CFA/ diminished by deletion of cfaD’ gene region from pNTP513, and was restored by acquisition of cfaD’ in trans. Furthermore, CFA/ expression by cfaD’ deletion mutant, the cfaABCE clone, was remarkably increased by the presence of cfaD’ in trans in a topoisomerase A deficient strain of E. coli DM800. These data suggest that cfaD’ region is a functional region of gene, that regulates the CFA/ expression with cfaR by unknown mechanism.

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。

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。

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%。

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。

河南豫东地区产志贺样毒素Ecoli O157∶H7感染病例的流行病学调查研究

[目的 ]探讨河南省局部地区腹泻病人感染及携带大肠杆菌O15 7∶H7的情况 ,观察带菌时间及预后。[方法 ]采用流行病学监测方法发现病人 ,通过病人粪便mEC肉汤增菌 14h、胶体金免疫卡筛选、免疫磁珠法集菌、CHROMAGAR O15 7∶H7显色培养基分离、rfbO15 7、rfbO111、hlyA、stx1、stx2、eaeA引物PCR扩增方法进行毒力因子测定等方法 ,观察、研究感染病人的发病和预后。[结果 ]从 130 3份腹泻病人中共分离出的 38株O15 7∶H7菌株 ,检出率 2 9% ,PCRrfbO15 7扩增均为阳性。其中 2株具有stx2、hlyA和eaeA毒力基因 ,36株为O15 7∶H7不产毒株。[结论 ]我省首次从病人中分离出O15 7∶H7产毒株 ,病人发病后可于第 3～

E．coli分泌表达载体的构建和人表皮生长因子在E．coli中的分泌性表达

采用ＰＣＲ技术从Ｅ．ｃｏｌｉ基因组片段中克隆出碱性磷酸酯酶（ＰｈｏＡ）的启动子和信号肽序列．在ＰｈｏＡ启动予５＇端设计了ＥｃｏＲⅠ酶切位点，在信号肽编码序列３＇端设计了ＨｉｎｄⅢ酶切位点．将ＰＣＲ产物酶切后ＥｃｏＲⅠ－ＨｉｎｄⅢ片段克隆至ｐＢＲ３２２的ＥｃｏＲⅠ－ＨｉｎｄⅢ位点，组构出含有ＰｈｏＡ启动子和信号肽序列的分泌表达载体ｐＢＭ－Ｐｈｏ－１．之后将人表皮生长因子的成熟肽基因克隆至该载体，使之在Ｅ．ｃｏｌｉ中获得分泌表达，另采用ｐＩＮⅢ载体系统以分泌方式表达了人表皮生长因子。

利用噬菌体T＿7RNA聚合酶在大肠杆菌（E．coli）中引导人尿激酶原克隆基因的表达

我们将人尿激酶原基因（ｐｒｏ－ＵＫ）重组到含Ｔ＿７基因１０启动子的质粒（ｐＥＴ３ｃ）中，用异丙基硫代半乳糖苷（ＩＰＴＧ）诱导，在大肠杆菌（Ｅ．ｃｏｌｉ）的ＢＬ２１（ＤＥ３）菌株中进行表达。经纤维蛋白平板测活法测得表达产物存在于包含体中。经变性和复性处理后，表达量达每升培养液１６００ＩＵ．用ＷｅｓｔｅｒｎＢｌｏｔ法鉴定表达产物为单一条带。分子量在４３ｋＤａ左右，略低于天然５４ｋＤａｐｒｏ－ＵＫ。这可能与Ｅ．ｃｏｌｉ中缺乏糖基化酶有关。

指状青霉提取物诱发E.coli ND-160及K12 infA基因突变

背景与目的:研究指状青霉(Penicillium digitatum)提取物对大肠杆菌菌株的致突变性。材料与方法:采用E.coli ND-160菌株回复突变试验、K12infA基因突变试验及其突变序列分析。结果:指状青霉提取物:①可明显地诱导ND-160菌株回复突变;②对K12茼株可诱发其infA基因DNA序列中5个碱基位点突变,且其中1个位点的突变还可导致编码相应氨基酸的改变(Lys→val)。结论:指状青霉对大肠杆菌基因有明显的致突变性。

用E.coli表达Canstatin-N及其表达条件优化

以重组质粒pET-CN为模板设计引物CASN1和CASN2,PCR方法扩增约267bp的人血管能抑素N端1～89氨基酸基因片段,用EcoR I和Sal I双酶切将其克隆进pET-22b(+)载体获得重组表达质粒pET-22b(+)-CN,转化E.coli BL21(DE3),用IPTG诱导表达Canstatin-N,产物以包涵体形式存在。本文在摇瓶发酵条件下研究了诱导剂浓度、诱导培养时间对目标蛋白表达的影响,结果表明IPTG的最佳诱导浓度为0.1mmol/L;37℃下诱导培养2h时产物表达量最高。纯化获得的融合his6的重组Canstatin-N具有免疫和抑制鸡胚绒毛尿囊膜(CAM)新生血管生成活性。

人胰岛素样生长因子Ⅰ型在E.coli和家蚕中的表达

将hIGF-I基因克隆进原核表达载体pET-28a(+),在E.coli中进行了融合表达,West-ern blotting显示在26 kD附近有一条特异条带。将hIGF-I基因克隆进pBacPAK-8,获得了杆状病毒转移载体pBacPAK-8-IGF-I,在脂质体的介导下,与线性化的家蚕杆状病毒共转染家蚕培养细胞Bm-N,经空斑筛选,PCR检测,获得了重组病毒Bm-Bac-hIGF-Ⅰ。SDS-PAGE检测表明,在感染重组病毒后,家蚕幼虫血淋巴中可以检测到一条分子量约为7.5 kD的特异性条带,ELISA检测表达量达4.51μg/mL蚕血淋巴。

Comparison of extended spectrum β-lactamasesproducing Escherichia coli with non-ESBLsproducing E.coli:drug-resistance and virulence

BACKGROUND:The virulent factors of Escherichia coli(E.coli) play an important role in the process of pathopoiesis.The study aimed to compare drug-resistant genes and virulence genes between extended spectrum β-lactamases(ESBLs)-producing E.coli and non-ESBLs-producing E.coli to provide a reference for physicians in management of hospital infection.METHODS:From October 2010 to August 2011,96 drug-resistant strains of E.coli isolated were collected from the specimens in Qingdao Municipal Hospital,Qingdao,China.These bacteria strains were divided into a ESBLs-producing group and a non-ESBLs-producing group.Drug sensitivity tests were performed using the Kirby-Bauer(K-B) method.Disinfectant gene,qacEA1-sull and 8 virulence genes(CNF2,hlyA,eaeA,VT1,est,bfpA,elt,and CNF1) were tested by polymerase chain reaction(PCR).RESULTS:Among the 96 E.coli isolates,the ESBLs-producing E.coli comprised 46(47.9%)strains and the non-ESBLs-producing E.coli consisted of 50(52.1%) strains.The detection rates of multiple drug-resistant strain,qacEA1-sull,CNF2,hlyA,eaeA,VT1,est,bfpA,elt,and CNF1 in 46ESBLs-producing E.coli isolates were 89.1%,76.1%,6.5%,69.6%,69.6%,89.1%,10.9%,26.1%,8.7%,and 19.6%,respectively.In the non-ESBLs-producing E.coli strains,the positive rates of multiple drug-resistant strain,qacEA1-sull,CNF2,hlyA,eaeA,VT1,est,bfpA,elt,and CNF1 were 62.0%,80.0%,16.0%,28.0%,64.0%,38.0%,6.0%,34.0%,10.0%,and 24.0%,respectively.The difference in the detection rates of multiple drug-resistant strain,hlyA and VT1 between the ESBLs-producing E.coli strains and the non-ESBLs-producing E.coli strains was statistically significant(P<0.05).CONCLUSION:The positive rate of multiple drug-resistant strains is higher in the ESBLsproducing strains than in the non-ESBLs-producing strains.The expression of some virulence genes hlyA and VT1 varies between the ESBLs-producing strains and the non-ESBLs-producing strains.Increased awareness of clinicians and enhanced testing by laboratories are required to reduce treatment failures and prevent the spread of multiple drug-resistant strains.