小檗碱对小鼠感染犊牛源生物被膜阳性、多重耐药大肠杆菌的体内抑菌作用

为阐明小檗碱对小鼠感染犊牛源生物被膜阳性、多重耐药大肠杆菌的体内抑菌作用，试验采用微量肉汤稀释法确定41株分离株的MIC值|采用改良结晶紫染色法，确定其生物被膜形成能力|采用ELISA法检测小鼠血清中IL-1β、IL-6、TNF-α的含量|采用血常规检测小鼠血液中白细胞、淋巴细胞、中性粒细胞数目及血红蛋白含量。结果显示：分离菌株对四环素、氨苄西林、甲氧苄啶、磺胺嘧啶耐药率较高，对阿米卡星、米诺环素、头孢西丁较为敏感|生物被膜形成能力无、弱、中、强的菌株数分别为14、10、7、10株|生物被膜阳性大肠杆菌耐10种以上药物的菌株占比73.9%，且多重耐药菌株占比66.7%|生物被膜强阳菌株中的多重耐药菌株占比80%|小檗碱高、低剂量组及联合给药组可不同程度降低小鼠血清中促炎因子的含量，降低血液中白细胞、淋巴细胞、中性粒细胞数目，并升高血红蛋白浓度。犊牛源大肠杆菌形成生物被膜可增强自身多重耐药性，且小檗碱具有成为临床治疗由生物被膜阳性、多重耐药大肠杆菌引起的犊牛腹泻病药物的潜力。 [关键词] 犊牛|大肠杆菌|生物被膜|小檗碱|促炎因子     

文昌鸡源大肠杆菌生物被膜表型和耐药谱型相关性研究

本试验分别采用微量肉汤稀释法和改良结晶紫法对65株文昌鸡源大肠杆菌进行15种临床常用抗菌药物耐药性检测和生物被膜形成能力鉴定,以了解海南文昌鸡源大肠杆菌耐药谱型和生物被膜表型之间的相关性。结果显示,65株文昌鸡源大肠杆菌中89.23%具有多重耐药现象,64.62%具有交叉耐药现象;81.54%的菌株具有不同的生物被膜形成能力,只有18.46%的菌株无细菌生物被膜形成能力。本试验结果表明,具有生物被膜形成能力的菌株大都表现出多重耐药性,但交叉耐药性与无生物被膜形成能力菌株相差不明显。     

纳米银抗菌及抗生物被膜机制研究进展

细菌耐药性及生物被膜感染问题一直备受关注，抗生素的使用不当或滥用导致了细菌耐药性越来越严重，一些细菌出现了多重耐药甚至超级耐药的情况。为了抵抗宿主的免疫反应及抗菌药物的攻击，细菌聚集后会形成生物被膜。生物被膜的形成进一步加强细菌的耐药性，生物被膜感染是细菌性疾病迁延不愈的重要原因之一。寻找广谱、高效的抗菌和抗生物被膜的抗生素替代物是目前的研究热点。纳米银(silver nanoparticles, AgNPs)由于自身的物理、化学和生物学特性，在抗菌及抗生物被膜方面受到广泛的关注，其抗菌机制主要包括了破坏细胞壁和细胞膜、DNA损伤、氧化应激等，抗生物被膜机制主要包括抑制相关基因的表达、抑制聚集黏附、阻断群体感应等。论文综述了纳米银抗菌及抗生物被膜的研究进展，以期为开发新型抗菌药物提供参考。     

云南南涧地区致仔猪腹泻性大肠杆菌血清型鉴定与耐药性分析

对2018—2020年采集的南涧县不同养殖场中患腹泻病仔猪肛拭子、粪便、肝脏等共243份病料进行大肠杆菌分离鉴定,采用人工感染小白鼠试验、玻板凝集试验、结晶紫微孔板法和K-B药敏纸片法,对分离的致泻性大肠杆菌的致病性、血清型、生物被膜形成能力及耐药性进行检测。结果显示,从243份仔猪腹泻病料组织中分离得到了113株大肠杆菌,其中有87株为致病性大肠杆菌,87株致病性大肠杆菌属于14种不同的血清型,以038 (17.2%)、0101 (18.4%)和0142 (14.9%)为主要流行优势血清型,强形成被膜能力菌株有24株(27.6%)、中形成被膜能力菌株有34株(39.1%)、弱形成被膜能力菌株有17株(19.5%)、不形成被膜菌株有12株(13.8%)。分离的87株致病性大肠杆菌对阿莫西林、氨苄西林、链霉素等10种药物的耐药率较高,耐药率在49.4%以上,对其他药物的耐药率在9.2%～26.4%之间。     

Ⅲ型分泌系统2转录因子YqeI对禽致病性大肠杆菌生物被膜调控机制的研究

生物被膜是导致细菌产生耐药性的主要原因之一,本文通过探究Ⅲ型分泌系统2(ETT2)转录调节因子YqeI对禽致病性大肠杆菌生物被膜形成的影响及其影响机制,为探究ETT2对禽致病性大肠杆菌致病机制的影响提供研究基础。利用Red同源重组的方法构建yqeI基因缺失株,并通过检测野生株与缺失株生物被膜形成能力、结合转录组学测序及荧光定量检测生物被膜基因表达量等,探究转录调节因子YqeI对禽致病性大肠杆菌生物被膜形成能力的影响。结果显示成功构建了yqeI基因缺失株,且yqeI的缺失并不影响生长曲线,但生物被膜形成能力显著下降,且相关生物被膜基因转录量显著下调。禽致病性大肠杆菌ETT2转录调节因子YqeI显著影响了禽致病性大肠杆菌生物被膜形成能力,为从ETT2及yqeI的角度发掘潜在的调控网络提供依据。     

金黄色葡萄球菌生物被膜研究进展

金黄色葡萄球菌生物被膜(BF)是由金葡菌黏附在载体上,大量聚集后形成团块状的菌团。目前通过实时荧光定量PCR、激光共聚焦显微技术或电镜扫描等技术手段可检测金葡菌生物被膜的相关基因及结构,进一步揭示其耐药机制,以便抗菌和抗生物被膜药物的研发,更有效防止金葡菌生物被膜的感染。     

Ⅲ型分泌系统2转录因子YqeI对禽致病性大肠杆菌生物被膜调控机制的研究

生物被膜是导致细菌产生耐药性的主要原因之一,本文通过探究Ⅲ型分泌系统2（ETT2）转录调节因子YqeI对禽致病性大肠杆菌生物被膜形成的影响及其影响机制,为探究ETT2对禽致病性大肠杆菌致病机制的影响提供研究基础。利用Red同源重组的方法构建yqeI基因缺失株,并通过检测野生株与缺失株生物被膜形成能力、结合转录组学测序及荧光定量检测生物被膜基因表达量等,探究转录调节因子YqeI对禽致病性大肠杆菌生物被膜形成能力的影响。结果显示成功构建了yqeI基因缺失株,且yqeI的缺失并不影响生长曲线,但生物被膜形成能力显著下降,且相关生物被膜基因转录量显著下调。禽致病性大肠杆菌ETT2转录调节因子YqeI显著影响了禽致病性大肠杆菌生物被膜形成能力,为从ETT2及yqeI的角度发掘潜在的调控网络提供依据。     

奶牛乳房炎大肠杆菌的青霉素耐药特征研究

为了研究奶牛乳房炎大肠杆菌的青霉素耐药特征,采用药敏纸片法检测了123株大肠杆菌对青霉素的耐药性,并利用β-内酰胺酶试剂盒测定耐青霉素株β-内酰胺酶活性,同时采用刚果红法和改良结晶紫半定量方法检测生物被膜的形成能力。结果表明:123株受试大肠杆菌中,对青霉素耐药的菌株有122株,耐药率99.19%。122株耐青霉素大肠杆菌中,生物被膜检测为阳性的菌株有92株(75.41%),β-内酰胺酶检测为阳性的有72株(59.02%);β-内酰胺酶阳性而生物被膜阴性的菌株有15株(12.30%),β-内酰胺酶和生物被膜同为阳性的有57株(46.72%);β-内酰胺酶为阴性但生物被膜为阳性的菌株有35株(28.69%)。92株生物被膜阳性菌株中,29株(31.52%)具有强成膜能力,61株(66.30%)具有中等成膜能力,2株(2.17%)成膜能力较弱。说明奶牛乳房炎大肠杆菌对青霉素的耐药率较高;大肠杆菌青霉素耐药性受β-内酰胺酶和生物被膜多种因子的共同调控。     

广州、成都宠物源性大肠杆菌生物被膜形成能力及耐药性调查

为了解广州、成都两地宠物源性大肠杆菌生物被膜形成能力和耐药情况,为指导宠物临床用药和耐药性监测提供依据,研究采用改良结晶紫半定量方法对300株宠物源性大肠杆菌进行生物被膜形成能力测定,同时采用NCCLS微量肉汤稀释法对之进行头孢噻呋、庆大霉素等14种兽医临床常用抗菌药物MIC值测定。结果表明:广州、成都两地宠物源性大肠杆菌形成生物被膜的能力均以中等和弱成膜能力表型为主,分别占两地分离菌株总数的93.3%和87.2%;广州、成都两地的分离菌株对14种兽医临床常用的抗菌药物表现出不同程度的耐药性,其中多西环素、利福平、氨苄西林、庆大霉素、氟苯尼考和阿莫西林/克拉维酸的耐药率均超过50.0%。     

广州、成都宠物源性大肠杆菌生物被膜形成能力及耐药性调查

为了解广州、成都两地宠物源性大肠杆菌生物被膜形成能力和耐药情况,为指导宠物临床用药和耐药性监测提供依据,研究采用改良结晶紫半定量方法对300株宠物源性大肠杆菌进行生物被膜形成能力测定,同时采用NCCLS微量肉汤稀释法对之进行头孢噻呋、庆大霉素等14种兽医临床常用抗菌药物MIC值测定.结果表明:广州、成都两地宠物源性大肠...     

大肠埃希菌生物被膜研究进展

细菌生物被膜指多个细菌黏附于机体或物体表面,分泌胞外多聚物将其自身包裹其中而形成的结构。研究表明人类许多细菌感染与生物被膜有关,生物被膜具有极高的抗药性和免疫逃逸能力,这也是许多细菌感染难以根除的重要原因之一,近年来已成为医学界关注的热点。大肠埃希菌是最重要的条件致病菌之一,论文从大肠埃希菌生物被膜的形态结构、检测方法、耐药机制、应对策略4个方面综述了大肠埃希菌生物被膜研究的进展。     

大肠埃希菌生物被膜体外模型的建立及其应用

以ATCC25922为研究对象,采用改良结晶紫染色、快速银染法和扫描电镜技术对其生物被膜进行定量和定性研究,建立大肠埃希菌生物被膜体外模型,利用优化的模型条件对249株临床分离株进行验证.采用琼脂平板计数法绘制大肠埃希菌浮游菌和被膜菌生长曲线,比较其生长特性的异同.对不同成膜能力的大肠埃希菌临床分离株进行色氨酸定量试验...     

The innate immune response of the bovine mammary gland to bacterial infection

Intra-mammary (IM) bacterial infection in cattle can result in clinical outcomes that range from being acute and life-threatening to those that are chronic and sub-clinical. The typical bacteria involved in IM bacterial infections activate the mammary immune system in different ways which can influence the severity of the outcome. A clear understanding of the mechanisms that activate and regulate this response is central to the development of effective preventative and treatment regimes. This review focuses on the different immune responses of the bovine mammary gland to common mastitis-causing pathogens. There is special emphasis on comparing the responses to Escherichia coli and Staphylococcus aureus infections, as these are typically associated, respectively, with acute/severe and chronic/sub-clinical forms of the disease.     

大肠埃希菌多重耐药性的形成机制

细菌耐药(尤其多重耐药)现象的出现,给我国养殖业带来巨大的经济损失,大肠埃希菌耐药性可分为原发性和获得性.大肠埃希菌外排泵功能增强、膜通透性下降均可以导致多重耐药的产生,而质粒、整合子/基因盒系统等可移动的遗传因子在多重耐药性的传播上有着重要作用.此外,细菌生物被膜的形成使细菌对多种抗菌药物产生强大的抵抗力.文章从上述几个方面阐述大肠埃希菌产生多重耐药的形成机制,并提出相应的防控对策.     

Host-response patterns of intramammary infections in dairy cows

Many different bacterial species have the ability to cause an infection of the bovine mammary gland and the host response to these infections is what we recognize as mastitis. In this review we evaluate the pathogen specific response to the three main bacterial species causing bovine mastitis: Escherichia coli, Streptococcus uberis and Staphylococcus aureus. In this paper we will review the bacterial growth patterns, host immune response and clinical response that results from the intramammary infections. Clear differences in bacterial growth pattern are shown between bacterial species. The dominant pattern in E. coli infections is a short duration high bacteria count infection, in S. aureus this is more commonly a persistent infection with relative low bacteria counts and in S. uberis a long duration high bacteria count infection is often observed. The host immune response differs significantly depending on the invading bacterial species. The underlying reasons for the differences and the resulting host response are described. Finally we discuss the clinical response pattern for each of the three bacterial species. The largest contrast is between E. coli and S. aureus where a larger proportion of E. coli infections cause potentially severe clinical symptoms, whereas the majority of S. aureus infections go clinically unnoticed. The relevance of fully understanding the bovine host response to intramammary infection is discussed, some major gaps in our knowledge are highlighted and directions for future research are indicated.     

The toll-like receptor-4 (TLR-4) pathway and its possible role in the pathogenesis of Escherichia coli mastitis in dairy cattle

Mastitis is one of the most costly production diseases in the dairy industry that is caused by a wide array of microorganisms. In this review, we focus on the Gram-negative Escherichia coli infections that often occur at periods when the innate immune defence mechanisms are impaired (i.e., parturition through the first 60 days of lactation). There is substantial evidence demonstrating that at these periods, the expected influx of polymorphonuclear neutrophil leukocytes (PMN) into the mammary gland is delayed during inflammation after intramammary infection with E. coli. Here, we provide some hypotheses on the potential mechanisms of action on how the disease may develop under circumstances of immunosuppression, and describe the potential involvement of the toll-like receptor-4 signal transduction pathway in the pathogenesis of E. coli mastitis. In addition, some ideas are proposed to help prevent E. coli mastitis and potentially other diseases caused by Gram-negative infections in general.     

奶牛隐性乳房炎奶样中埃希氏大肠杆菌共同性抗原初探

用LMT的方法对新疆8个奶牛场采集的1020份奶样进行隐性乳房炎的检测,并对阳性样品进行了大肠杆菌的分离与鉴定。从不同牛场分离菌株中挑选8株用家兔制备免疫血清,用试管凝集对从乳房炎奶样分离出的其它21株大肠杆菌进行共同性抗原的筛选。结果显示,免疫血清效价达1∶2560～1∶5120,85.7%的待检菌株与其中3种血清凝集反应呈阳性。对制备血清的8株菌进行SDS-PAGE电泳分析,菌体蛋白图谱显示在20~84 ku处存在大量相同或相似的蛋白条带;用制备的免疫血清进行免疫印迹分析,与8株菌的菌体蛋白在70 ku处呈现明显的抗原抗体反应。说明这些菌株存在共同性抗原。     

In vitro evaluation of the impact of silver coating on Escherichia coli adherence to urinary catheters

A silver-coated urinary catheter was compared to a non-silver-coated urinary catheter for the ability to reduce adherence of 6 isolates of Escherichia coli. Catheters were incubated with E. coli strains for 0, 24, 48, and 72 h. Broth was sampled at all time points to determine CFU/mL. Catheters were subjected to sonication to determine adhered bacteria at all time points, and scanning electron microscopy (SEM) to semi-quantitatively assess biofilm formation. Silver-coated catheters had significantly less adhered bacteria than non-silver-coated catheters at times 24, 48, and 72 h. Subjectively, silver-coated urinary catheters had less biofilm formation than non-silver-coated urinary catheters as assessed by SEM. Silver coating of catheters was associated with reduced adherence of E. coli in an in vitro evaluation. Testing of catheters in dogs in vivo is required to determine if there is a reduction in catheter-associated urinary tract infections.     

Canine bacterial urinary tract infections: new developments in old pathogens

Uncomplicated bacterial urinary tract infections (UTIs) occur commonly in dogs. Persistent or recurrent infections are reported less frequently. They typically occur in dogs with an underlying disease and are sometimes asymptomatic, especially in dogs with predisposing chronic disease. Escherichia coli is the organism most frequently cultured in both simple and complicated UTIs. Organisms such as Enterococcus spp. and Pseudomonas spp. are less common in uncomplicated UTI, but become increasingly prominent in dogs with recurrent UTI. The ability of bacteria to acquire resistance to antimicrobials and/or to evade host immune defence mechanisms is vital for persistence in the urinary tract. Antimicrobial therapy limitations and bacterial strains with such abilities require novel control strategies. Sharing of resistant bacteria between humans and dogs has been recently documented and is of particular concern for E. coli O25b:H4-ST131 strains that are both virulent and multi-drug resistant. The epidemiology of complicated UTIs, pathogenic traits of uropathogens and new therapeutic concepts are outlined in this review.