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.

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.

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。

猪致病性大肠杆菌的分离鉴定及耐药性分析

从湖北省襄樊地区7家猪场采集病料进行大肠杆菌分离培养,获得36株菌株。通过菌落和细菌形态学观察、生化试验和动物试验确定分离细菌为致病性大肠杆菌。应用纸片扩散法对分离的大肠杆菌进行药物敏感试验,结果表明,对丁胺卡那霉素敏感的菌株有81%,氟苯尼考42%,庆大霉素39%,痢菌净33%,新霉素31%。对阿莫西林耐药的菌株为86%,氯霉素72%,土霉素56%,卡那霉素47%、庆大霉素47%。通过本次试验可知丁胺卡那霉素可作为襄樊地区防治致病性大肠杆菌的首选药物,氟苯尼考作为备选药物。

马麝呼吸系统疾病病原学研究

采用病毒、真菌、细菌学及血清学等检验方法,对甘肃兴隆山马麝以出血性肺炎或纤维素性-化脓坏死性肺炎为主要特征的呼吸系统疾病的病原进行了系统研究。结果表明,马麝的呼吸系统疾病是由巴氏杆菌(P.multocida)单独感染或与大肠杆菌(E.coli)、绿脓杆菌(P.aeruginosa)混合感染的一种普通传染性疾病。药敏试验表明,这3种细菌均对苄星青霉素、硫酸链霉素、复方磺胺甲噁唑片、酒石酸泰乐菌素敏感,而对麦迪霉素不敏感。

耐药大肠杆菌的致病性与免疫原性

目的了解大肠杆菌耐药株的致病性与免疫原性。方法临床分离耐药大肠杆菌,经适宜条件培养后接种小鼠,观察耐药菌株对小鼠的致病性;并选择已知血清型的不同耐药谱和不同耐药水平的菌,分别培养至对数生长期,经甲醛灭活后免疫小鼠,2周后分别用致死剂量的原菌株和同期分离菌株进行攻毒,考察耐药菌株免疫原性。结果24株耐药菌普通肉汤培养物分别感染小鼠,在接种后18h,存活率仅为4%。只有2株菌在1周内仍不能将小鼠全部致死,经小鼠体内传3代后,可在18h内致死小鼠。耐药谱广的菌株感染的小鼠,心肌发生颗粒变性、局灶性出血、坏死;肝脏糖元溶解,脂肪变性;脾脏轻度淤血,淋巴细胞减少;肾脏出血,肾小球肾炎,上皮细胞颗粒变性,水泡变性。而耐药种类少的菌株与对照敏感菌株感染的小鼠主要特征为脾脏出血、淤血,坏死,脾小体消失;肠上皮细胞坏死、脱落、卡他性肠炎。免疫小鼠以免疫用菌株攻毒,均可得较高的保护率,最低为75%,最高为100%。免疫小鼠用非免疫菌株攻毒,小鼠感染后症状出现较缓慢,在18h后出现死亡高峰。耐药种类少的菌株免疫小鼠,对同期分离的非免疫用的致病性大肠杆菌攻击的保护率偏低,而对受试的11种抗生素耐受7种以上的菌株免疫小鼠后,对致病大肠杆菌攻击的保护率显著提高,多数达到75%以上,经统计学分析差异显著。结论耐药大肠杆菌具有较强致病性,且耐药特性与其免疫保护效果相关,多重耐药株对当前流行菌株具有更好的免疫保护作用。

产毒性大肠杆菌(ETEC)中毒力岛分布的研究

目的 了解小肠结肠炎耶尔森菌强毒力岛在产毒性大肠杆菌中的分布，以便于进一步深入研究毒力岛在大肠杆菌中的结构的完整性和功能。方法ＰＣＲ扩增和原位杂交及基因序列分析。结果 在检测的９３株产毒性大肠杆菌（ＥＴＥＣ）的毒力岛的检出率为 ３２．２５％（３２／９３），而且这些阳性菌株中的毒力岛大部分连接到 ａｓｎｔＲＮＡ（天门冬氨酸ｔＲＮＡ）位点。结论 产毒性大肠杆菌是致病性较强的病原菌之一，而小肠结肠炎耶尔森菌强毒力岛在产毒性大肠杆菌中阳性率较高的分布．

甘肃部分地区致羔羊腹泻大肠埃希菌的分离鉴定及耐药性分析

为调查甘肃地区大肠埃希菌对新生羔羊腹泻的致病性及其耐药性,从甘肃省8个养殖场采集新生腹泻羔羊粪便92份。采用16S rDNA扩增结合微生物鉴别培养技术对病料中的致病性大肠埃希菌进行鉴定,随机选取分离的6株菌株进行致病性试验,并采用Kirby-Bauer纸片琼脂扩散法对分离得到的菌株进行耐药性分析。结果表明,从92份病料中分离得到21株致病性大肠埃希菌,选取的6株菌均有一定的致病性,耐药性分析结果显示该地的大肠埃希菌对羊场常用的多种抗生素耐药。表明大肠埃希菌仍是引起甘肃地区新生羔羊腹泻的主要病原菌,而且耐药性严重。

吉林省动物病原性大肠杆菌的耐药性监测试验

从吉林省 5个地区分离出动物病原性大肠杆菌 132株 ,采用药敏纸片法对 2 2种抗生素进行了耐药性监测试验。结果表明 :受检菌株全部对 1种或多种抗生素耐药 ,无一全部敏感株。对 13～ 15种抗生素耐药的菌株数较多。其中对氧氟沙星、诺氟沙星、环丙沙星、氯霉素、庆大霉素、卡那霉素、呋喃妥因同时耐药的菌株已达半数。采用平皿二倍稀释法测定随机挑选的 4 0株大肠杆菌对 6种抗生素最低抑菌浓度的结果为耐药水平很高。因而 ,采取有效的方法抑制大肠杆菌对多种抗生素的耐药已是当务之急。