The virulence regulator AbsR in avian pathogenic Escherichia coli has pleiotropic effects on bacterial physiology

Avian pathogenic Escherichia coli(APEC)belonging to extraintestinal pathogenic E.coli(ExPEC)can cause severe infections in extraintestinal tissues in birds and humans,such as the lungs and blood.MprA(microcin production regulation,locus A,herein renamed AbsR,a blood survival regulator),a member of the MarR(multiple antibiotic resistance regulator)transcriptional regulator family,governs the expression of capsule biosynthetic genes in human ExPEC and represents a promising druggable target for antimicrobials.However,a deep understanding of the AbsR regulatory mechanism as well as its regulon is lacking.In this study,we present a systems-level analysis of the APEC AbsR regulon using ChIP-Seq(chromatin immunoprecipitation sequencing)and RNA-Seq(RNA sequencing)methods.We found that AbsR directly regulates 99 genes and indirectly regulates 667 genes.Furthermore,we showed that:1)AbsR contributes to antiphagocytotic effects by macrophages and virulence in a mouse model for systemic infection by directly activating the capsular gene cluster;2)AbsR positively impacts biofilm formation via direct regulation of the T2SS(type II secretion system)but plays a marginal role in virulence;and 3)AbsR directly upregulates the acid tolerance signaling system EvgAS to withstand acid stress but is dispensable in ExPEC virulence.Finally,our data indicate that the role of AbsR in virulence gene regulation is relatively conserved in ExPEC strains.Altogether,this study provides a comprehensive analysis of the AbsR regulon and regulatory mechanism,and our data suggest that AbsR likely influences virulence primarily through the control of capsule production.Interestingly,we found that AbsR severely represses the expression of the type I-F CRISPR(clustered regularly interspaced short palindromic repeats)-Cas(CRISPR associated)systems,which could have implications in CRISPR biology and application.

Isolation and Identification of a Pathogenic E.coli Strain Causing Diarrhea in Foxes

[Objectives] The study aimed to identify the pathogenic E. coli strain that caused diarrhea in foxes and to analyze its drug sensitivity.[Methods] A pathogenic E. coli strain was isolated from dead foxes with diarrhea. By conventional bacterial isolation and culture, morphological observation, pathogenicity test and K-B disc method, the isolated strain was identified as pathogenic E. coli .[Results] The isolated pathogen was highly sensitive to ceftriaxone, cefotaxime, ciprofloxacin and lincomycin, moderately sensitive to enrofloxacin, neomycin, gentamycin, spectinomycin, florfenicol, amikacin and polymyxin, and resistant to ampicillin, amoxicillin and doxycycline.[Conclusions] This study provided reference for the prevention and control of diarrheal diseases in foxes in Qinhuangdao region.

Solar photocatalytic pathogenic disinfection:Fundamentals to state-of-the-art

It is necessary to treat pathogen-infected water before its utilisation.Of conventionally used treatment methods,solar photocatalysis has gained considerable momentum owing to its operational simplicity and capacity to use freely and abundantly available solar energy.This article systematically reviewed the disinfection of water with photocatalysis.It addressed the concerns of microbial infection of water and the fundamentals behind its treatment with photocatalysis.It presented an in-depth description of pathogenic deactivation with powerful reactive oxygen species.Special emphasis was given to process intensification as it is an attractive technique that provides multifunctionality and/or equipment miniaturisation.Solar reactor design regarding mobilised/immobilised photocatalysts and compound parabolic concentrators were elucidated.Finally,key parameters governing photoperformance,corresponding trade-offs,and the need for their optimisation were discussed.Overall,this article is a single point of reference for researchers,environmentalists,and industrialists who address the ever-severing challenge of providing clean water whilst also maintaining energy sustainability.

一株致多发性浆膜炎猪源肠外E.coli的分离与鉴定

无菌采集多发性浆膜炎病猪的心血、肝脏,进行细菌分离培养,并对分离菌株进行染色镜检、生化试验、PCR鉴定、小鼠致病性试验和药敏试验。结果显示,分离菌株为肠外致病性大肠杆菌;分离菌株对庆大霉素、恩诺沙星、强力霉素、氨苄西林、磺胺类药物、头孢噻肟等均耐药,对阿米卡星、多粘菌素、美罗培南、亚胺培南敏感。本研究为致多发性浆膜炎的猪大肠杆菌病的诊断与防治提供了参考依据。

UV-TiO_2 photocatalytic disinfection and photoreactivation of pathogenic bacterium in municipal wastewater

The disinfected bacteria will be a photoreactivation under the irradiation of the sunlight,and the light intensity plays an important role in the bacteria resurrection.The effect of light intensity on photoreactivation of Escherichia coli(E.coli) and Enterococcus faecalis(E.faecalis) in secondary effluents which were disinfected respectively by pure UV and UV-TiO_2 was investigated.The results show that the disinfection efficiency of UV-TiO_2 is much higher than that of the pure UV disinfection.The photoreactivation rate of E.coli is much higher in pure UV disinfection than in UV-TiO_2 photocatalytic disinfection.Under high light intensity in UV-TiO_2 disinfection,high resurrection rate can be induced.However,a higher resurrection rate can be introduced even under low light intensity in pure UV disinfection alone.Meanwhile,UV-TiO_2 disinfection has a strong inhibition effect on E.faecalis photoreactivation.When the light intensity is lower than 21 μW/cm^2,nearly no resurrection of E.faecalis occurs after 72 h resurrection irradiation,and a little resurrection rate is observed only under a strong photoreactivating light intensity.

Detection of High Pathogenicity Island(HPI) in Pathogenic Escherichia coli of Mink by PCR

[Objective] The paper was to analyze the carrying status of high pathogenicity island （HPI） in pathogenic Escherichia coli of mink. [Method] Eight strains of E. coli were isolated from dead mink, and conducted pathogenicity test of artificial infection. The carrying status of HPI （irp2, fyuA） was detected by PCR. [Result] Eight strains of E. coli were pathogenic E. coli, and the carrying rate of HPI （irp2, fyuA） was 100%, positively correlated with the pathogenicity. [Conclusion] The results lay a foundation for further exploring the pathogenic mechanism of E. coli..

Pathogenicity of Escherichia coli O_(123) from Rex Rabbit on White Mice

[Objective]The paper was to analyze the pathogenesis of Escherichia coli O123 from rex rabbit. [Method]E. coli O123 isolated from rabbit liver with diarrhea symptom in scale rex rabbit farm was intraperitoneally injected into 18- 22 g Kunming mice,and its pathogenicity was determined by clinical symptoms and pathological examination. [Result]When the inoculation concentration was about 8. 5 × 107 CFU /mL,Kunming mice appeared the clinical symptoms of drooping spirit,diarrhea and gathering,and the mortality reached 50%. Anatomical examination found that intestinal wall was thinning and intestinal mucosa was bleeding. [Conclusion]E. coli from rex rabbit has strong pathogenicity,and establishing animal model with Kunming mice to study its pathogenesis is of great reference significance for diagnosis and prevention of E. coli disease of rex rabbit.

A Comparative Investigation on Growth of Three Food Born Pathogenic Bacteria Inoculated with Withania somnifera:an Invitro Experimental Study

Background:Withania somnifera(WS)is proposed as one of the alternatives instead of the antibiotic.This study is aimed to evaluate the inhibitory potency of enzymatic extract of the fruits of the WS.Methods:As an invitro experimental study,the growth rate of Shigella dysenteriae,Salmonella typhimurium,and Escherichia coli inoculated in different concentrations(25%,12.5%,6.25%and 3.125%)of the extract were assessed.A microtitre plate method was conducted.ANOVA was applied to identify statistical differences with p-value<0.05.Results:Different concentrations of extract,in comparison with control,declined the growth rate of all tested bacteria.All concentrations inhibited the growth of S.typhimurium(p<0.05).Compared to the microorganism control,effective concentration of the extract inhibiting the growth of E.coli was 12.5%,and 6.25%,while it was 12.5%,and 6.25%for Sh.dysenteriae(p<0.05).A dose-dependent response of E.coli was observed.The antibacterial activity of the extract tested was found mainly against E.coli and Sh.dysenteriae.The most resistant microorganism compared to E.coli and Sh.dysenteriae was S.typhimurium(p<0.05).25%of the concentration of the extract showed the different inhibitory effect among three tested bacteria(p<0.05).Conclusions:The extract was labeled as an antibacterial agent against the representative of three foodborne bacteria,Invitro.The common effective concentrations of the extract(12.5,and 6.25%)is recommended for further research,as food additive,to remedy digestive ailments related to E.coli,S.typhimurium and Sh.dysenteriae.

犊牛源肠外致病性大肠杆菌分离鉴定、致病性及耐药性分析

【目的】确定新疆喀什地区某规模化牛场致犊牛死亡的细菌性病原体及其生物学特性,为该地区规模化牛场细菌病的防治和合理用药提供参考。【方法】对死亡犊牛进行病理解剖及病原分离,挑选肝脏(KS-1)与肛拭子(KS-2)来源的单菌落纯化培养,通过形态观察、生化试验、16S rRNA基因扩增及系统进化分群鉴定分离株,并通过毒力基因检测、致病性试验及药敏试验对分离株的致病性和耐药性进行研究。【结果】死亡犊牛肺脏、肝脏、心血、关节液和肠系膜淋巴结以及健康犊牛肛拭子样品接种后菌落生长形态一致,结合选择性培养基上菌落生长形态、革兰染色镜检形态特点、生化特性及大肠杆菌16S rRNA的验证,鉴定分离菌株为大肠杆菌。系统进化分群试验中,KS-1为A群,KS-2为B1群。毒力基因检测结果显示,KS-1携带crl、papC、hlyE、eaeA、ompA、ompC、iucD和iutA共8种毒力相关基因,KS-2携带crl、hlyE和ompF共3种毒力相关基因。致病性试验结果显示,腹腔注射1×108 CFU分离株感染小鼠,KS-1组小鼠在16 h内全部死亡,KS-2组小鼠无死亡现象出现。药敏试验结果显示,KS-1对哌拉西林/他唑巴坦、头孢唑林、头孢呋辛等17种药物敏感,对氨苄青霉素/舒巴坦和哌拉西林中度敏感,对氨苄西林和复方新诺明耐药;KS-2对哌拉西林/他唑巴坦、头孢替坦、亚胺培南、美罗培南、阿米卡星和呋喃妥英敏感,对妥布霉素中度敏感,对其余14种药物耐药。【结论】本研究分离出2株犊牛源大肠杆菌,其中KS-1毒力较强,且携带丰富的毒力基因,对大部分常用抗生素敏感,对氨苄西林和复方新诺明具有耐药性;KS-2携带毒力基因较少,呈现多重耐药。

黄芩苷对猪源肠外致病性大肠杆菌的体内保护作用

为探究黄芩苷对猪源肠外致病性大肠杆菌(Extraintestinal pathogenic Escherichia coli,ExPEC)感染小鼠后的保护作用,采用小鼠存活率试验和组织载菌量试验评估黄芩苷对小鼠的保护作用,比较感染组和黄芩苷治疗组小鼠临床表现、存活率、组织载菌量及病理变化。结果表明,猪源肠外致病性大肠杆菌感染后小鼠状态萎靡不振、食欲下降,黄芩苷治疗组小鼠状态较感染组状态好;黄芩苷治疗组小鼠存活率相对于感染组有一定提升;黄芩苷治疗组小鼠心脏、肝脏、脾脏和肾脏中组织载菌量及病理变化相对于感染组均极显著降低(P<0.01)。

猪源肠外致病性大肠杆菌的分离与鉴定

目的检测猪源肠外致病性大肠杆菌(ExPEC)的血清型与毒力基因。方法对2013-2014年间秦皇岛地区30份组织病料采用细菌形态观察、培养特性试验、生化试验鉴定出8株肠外致病性大肠杆菌。采用玻片凝集法测定这些大肠杆菌病的血清型,并用PCR扩增法检测9种毒力基因。结果定型菌株5株,分别属于O53、O93和O157 3个血清型,9种毒力基因PCR检测结果表明ler、iutA、irp2、fyuA、astA 5种基因检出率分别为100%、75.0%、50.0%、50.0%、25.0%。结论所检测的猪源肠外致病性大肠杆菌以O53、O93和O157为主要流行血清型,同时携带fyuA、ler和iutA基因的菌株致病性较强。

肠外致病性大肠埃希菌多重耐药性及氨基糖苷类耐药基因分析

目的检测临床分离猪、鸡源肠外致病性大肠埃希菌的耐药性,分析其携带的氨基糖苷类耐药基因,以指导临床用药,探究细菌对氨基糖苷类抗生素的抗性机制。方法应用K-B法测定分离株对19种常用抗生素的耐药情况。用双纸片法检测产ESBLs菌株并进行基因分型。用PCR和测序方法检测氨基糖苷类抗性基因aadA1,aadA2,strA-strB,aadB,aacC2,aac(3)-IV,aph(3′)-Ia,aph(3′)-IIa。结果临床分离株表现多重耐药性,对头孢菌素类药物和阿米卡星的敏感性最高(63%～97%),93%的菌株耐药谱值≥10。共检测到两株产超广谱β-内酰胺酶(ESBLs)菌株,基因型属TEM-1+CTX-M-14。耐药菌株与相应的氨基糖苷类耐药基因符合率高(≥74%)且序列保守。结论猪、鸡源肠外致病性大肠埃希菌呈多重耐药性,其对氨基糖苷类抗生素的抗性机制以产生针对该类抗生素的修饰酶为主。

规模化养鸭场鸭源大肠杆菌分离株的致病性及系统发育分析

为研究鸭源大肠杆菌(E.coli)的致病性,明确鸭病原性E.coli与人和其他动物E.coli的亲缘关系及O血清型与菌种间遗传关系的相关性,本研究从我国西南地区规模化养鸭场患典型E.coli败血症的雏鸭体内分离37个血清型共82个E.coli分离株(其中优势血清型32株,其他血清型50株),以每株0.2 mL(l09 cfu/mL)腿部肌肉接种7日龄健康鸭进行致病性试验;并对其中14个鸭源E.coli代表株进行16S rRNA基因克隆、测序及系统发育分析。结果表明:所有分离株全部为致病性E.coli,其中高致病株、中等致病株和低致病株分别占受试菌株的80.5%(66/82)、17.1%(14/82)和2.4%(2/82),4个优势血清型全部为高致病株和中等致病株,分别占受试菌株的84.4%(27/32)和15.6%(5/32);14个代表株鸭源E.coli的16S rRNA形成2个主要分支,3株新发现的血清型单独形成一个较远的分支,11株常见血清型与人及其他动物源E.coli形成另一个大的分支,其中有6株与人的O157亲缘关系较近,2株与出血性E.coli O157∶H7 sakai聚为一个小分支;从遗传进化的关系分析,这些菌株有可能是人类的潜在病原菌;同时还发现不同血清型的分离株可以聚为一支,而同一血清型的分离株可以处于不同的分支,常规的O血清学分型不能体现菌种间遗传关系的远近。

规模化猪场致病性大肠杆菌、沙门氏菌药敏区系调查

从四川省 1 6个和广西 1个规模化猪场临诊发生典型仔猪黄、白痢猪只的肛试粪样及死亡猪只的心血和肝中分离出致病性大肠杆菌 2 45株 ,从四川省 1 2个规模化猪场临诊发生典型仔猪副伤寒猪只中分离出致病性沙门氏菌 2 7株。用 1 6种常用抗菌药物对分离菌株进行了药敏测定 ,结果表明 ,大肠杆菌、沙门氏菌存在广泛的耐药性 ,以多重耐药性为主。大肠杆菌菌株最为敏感的药物是头孢唑啉、新霉素 ,而对林可霉素、青霉素钾的敏感率极低。对沙门氏菌菌株最为敏感的药物是新霉素、磺胺、庆大霉素、妥布霉素等 ,而对红霉素、林可霉素几乎全部耐药。

规模化猪场致病性大肠杆菌血清型鉴定

从四川省 1 6个规模化猪场临诊发生典型仔猪黄、白痢猪只的肛试粪样及死亡猪只的心血和肝中分离出致病性大肠杆菌 2 45株 ,用 35种大肠杆菌单价O抗原进行血清型鉴定。 2 45株分离菌有 1 72株能定型 ,分属 30种血清型 ,其中以O6 0、O89、O1 1 9、O1 41、O9、O2 0、O1 37和O1 0 1等 8种血清型为优势血清型 ,占定型菌株的 6 6 86 %。尚有 73株未能定型 ,占分离菌株的 2 9 80 % (73/2 45 )。

辽宁地区奶牛乳房炎细菌性病原分离鉴定及大肠杆菌药敏试验

为了掌握辽宁地区奶牛乳房炎主要细菌性病原种类及致奶牛乳房炎大肠杆菌药物敏感性特征,本研究选取辽宁地区某大型奶牛场75头临床表现为乳房炎的奶样进行细菌培养与分离,通过生化方法对分离到的细菌进行鉴定,并对分离到的奶牛源大肠杆菌进行体外药物敏感性试验研究。结果发现,该场奶牛乳房炎细菌性病原主要为大肠杆菌、葡萄球菌和链球菌,其检出率分别为58.7%、64.0%和54.7%,存在二重感染和三重感染等混合感染的情况。大肠杆菌药物敏感性试验结果表明,该场分离株对磺胺类药物(耐药率>85%)及氯霉素类药物(耐药率>30%)耐药性较高,对氨苄西林(9.5%)、环丙沙星(9.5%)、头孢噻呋(7.1%)和氧氟沙星(4.8%)比较敏感。上述研究结果为该地区奶牛乳房炎的防制提供可靠的理论依据。

猪致病性大肠杆菌耐药质粒检测及其中药消除作用研究

为探讨中药对河南省规模化养猪场致病性大肠杆菌(E.coli)耐药质粒消除的效果,本研究在对87个猪致病性E.coli分离株进行耐药质粒检测的基础上,将各分离株分别于含有不同浓度的石榴皮、黄芩、黄连等中药提取液的培养液中培养,进行耐药质粒消除试验;并采用影印培养法和纸片扩散法进行耐药性消除菌落筛选及其对抗菌药物敏感性恢复的检测。结果表明:各分离株均含有2个～8个质粒,大小约为1.0 kb～87.0 kb;经石榴皮、黄芩、黄连作用后,各分离株均可以获得数量不等的耐药性消除菌落,消除率为0.34%～16.2%,以黄连的平均消除率最高,为9.33%;在耐药性消除的各分离株中,有25个分离株未发生质粒消除,其余均消除了1条～3条质粒,并且对7种抗菌药物的平均敏感率由消除前的5.39%分别提高至60.4%、75.2%和76.5%。表明石榴皮、黄芩、黄连对猪致病性E.coli具有质粒消除和耐药性逆转作用,其中黄连作用效果最好。

大肠杆菌外膜蛋白A研究进展

大肠杆菌病血清型众多、易继发、地域性强、耐药性突出、暴发率高。鸡大肠杆菌病已严重影响中国养禽业,在实践中主要以预防为主。文章综述了大肠杆菌及其致病因素外膜蛋白的基本概况和外膜蛋白A的研究现状。

山羊呼吸系统疾病病原分析

为了调查广西省某山羊场一起羊呼吸道疾病的病原,本试验采取流行病学调查、临床症状与病理变化观察、病原分离鉴定、生化试验、PCR及致病性试验等方法对病原进行分析,并根据流行病学特点和药敏试验结果进行防控。结果表明,从病死山羊的肺脏组织中分离出MS1和MS2两株革兰氏阴性的致病杆菌,分离培养或PCR检测发现支原体、流感病毒和寄生虫均为阴性。MS1菌株生化特性符合黏质沙雷氏菌,其16SrRNA基因测序结果与GenBank上登录的黏质沙雷氏菌核苷酸序列同源性达到99%以上;MS2菌株生化特性符合大肠杆菌,其16SrRNA基因测序结果与GenBank上登录的大肠杆菌核苷酸序列同源性达到99%以上,两株菌对小白鼠均具有致病性。大肠杆菌和黏质沙雷氏菌均对壮观霉素、阿米卡星、卡那霉素和新霉素高度敏感,用高敏药物卡那霉素联合地塞米松等相关措施进行治疗,收到良好效果。

奶牛子宫内膜炎大肠杆菌耐药性及其与整合子关系的研究

为阐明奶牛子宫内膜炎大肠杆菌的耐药性及其与细菌携带整合子之间的关系,采用微量稀释法测定药物对各菌株的最小抑菌浓度,以确定菌株的耐药性;运用PCR方法检测细菌携带I类整合子的情况。结果:所有菌株对头孢噻呋、呋喃唑酮以及喹诺酮类药物的耐药率较低,均小于35%,而对磺胺类和抗菌增效剂的耐药率较高,均在97%以上;57株大肠杆菌中有21株携带I类整合子,阳性率为36.8%,且I类整合子阳性菌株均为多重耐药菌株(耐8种以上抗菌药物);整合子阳性菌株对链霉素、阿莫西林、氨苄西林、头孢噻吩、四环素、土霉素的耐药率均显著高于整合子阴性菌株。结果表明奶牛子宫内膜炎致病性大肠杆菌的耐药性和多重耐药性与整合子携带有着密切关系。