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1.
目的 了解贵州省鸡源空肠弯曲菌的分子流行特征,阐明各地菌株间的亲缘关系和进化特征。方法 在贵州省随机抽取7个大型养鸡场,共采集210份鸡的新鲜粪便样本,分离培养出38株空肠弯曲菌,采用多位点序列分型对分离株的序列型及克隆复合体进行构成和聚类分析,与PubMLST数据库中来自国内的分离株分子特征进行比较。结果 贵州省38株鸡源空肠弯曲菌分为23种ST型和8个克隆复合体,其中9种是目前中国大陆地区已有的ST型,2个等位基因和8种序列型为新发现的。ST型构成比前四位分别是ST - 45、ST - 161、ST - 354、ST - 4 324,与数据库中已有的6株贵州来源菌株相比,不存在共同的ST型。优势克隆复合体(CC - 45、CC - 354、CC - 52)与数据库中鸡源分离株的前三位克隆复合体没有重叠。菌株遗传进化树显示,本研究中属于优势克隆复合体的18株菌与国内部分人源、猪源、野生鸟源、鹅源分离株有较近的遗传距离。结论 贵州省鸡源空肠弯曲菌具有高度遗传多样性,在一定程度上表现出地域流行特征。序列型与国内华东地区的分离株有较高的交叉性,部分分离株与国内人、野生鸟、鹅等来源分离株遗传距离近,应加强对不同地区、不同宿主来源空肠弯曲菌的动态监测。  相似文献   
2.
弯曲菌是全球范围导致人类肠道感染的主要病原体之一,通常引起腹泻、腹部绞痛、呕吐、发热等多种临床症状,某些菌型可导致反应性关节炎、吉兰-巴雷综合征(格林-巴利综合征)及米勒-费希尔综合征等并发症。弯曲菌广泛存在于各种动物、环境介质以及媒介生物中,引起外源性感染的传播来源和传播链尚未完全揭示。同时还有部分弯曲菌自然定殖在人类口腔中,可能引起内源性感染。本文就近年来人类弯曲菌感染所涉及的宿主以及归因分析方面的研究文献进行概述,为今后控制和消除人类弯曲菌感染风险提供指导。  相似文献   
3.
目的 了解温州市弯曲菌引起腹泻的流行病学特点,掌握弯曲菌的耐药状况、分子型别特征。方法 在2017至2019年间对2家温州市区哨点医院的腹泻病例进行流行病学调查,并采集粪便标本进行弯曲菌的分离培养和常规生化鉴定,采用聚合酶链反应(Polymerase Chain Reaction, PCR)进一步鉴定,同时进行药敏试验、多位点序列分型(Multilocus-sequence typing, MLST)研究。结果 909例腹泻病例弯曲菌检出率为10.2%(93/909),空肠弯曲菌和结肠弯曲菌阳性率分别为8.9%(81/909)和1.3%(12/909)。6个年龄组间及不同季节的弯曲菌阳性率差异无统计学意义(χ年龄2=2.09,P>0.05;χ季节2=0.468,P>0.05)。93株弯曲菌对11种抗菌药物共产生了22种耐药谱,耐萘啶酸(Nalidixic acid, NAL)-环丙沙星(Ciprofloxacin, CIP)-四环素(Tetracycline, TET)谱型最多,占38.7%(36/93)。空肠弯曲菌和结肠弯曲菌多重耐药率(耐3种以上抗生素)分别为42.0%(34/81)、50.0%(6/12)。MLST分型结果显示本地分离株中,空肠弯曲菌被分成54 种ST型,含15 个克隆群,最多的克隆群为ST45CC,占11.1%(9/81),结肠弯曲菌分为8 种ST型,主要的克隆群为ST828CC,占83.3%(10/12)。本研究共发现16个新的ST型。结论 温州市食源性腹泻病例中弯曲菌已成为主要病原,且呈现很高的多重耐药性,在遗传特征上表现为遗传多样性。  相似文献   
4.
目的以OMP18的B细胞抗原表位多肽为包被抗原,建立检测空肠弯曲菌感染的ELISA方法。方法以不同浓度梯度(0.1,1,10μg/mL)OMP18的B细胞抗原表位多肽进行包被,以空肠弯曲菌全菌兔抗IgG为一抗,HRP标记的羊抗兔抗体IgG为二抗,检测对原浓度1mg/mL的不同稀释度(1∶10,1∶100,1∶1 000)抗体IgG水平。分别以空肠弯曲菌感染兔血清、健康兔血清及沙门菌感染兔血清为一抗,1∶3 000稀释的HRP标记的羊抗兔IgG为二抗,比较各抗原表位多肽的免疫特异性。结果 OMP18的B细胞抗原3个表位多肽在稀释度在1∶1 000、1∶4 000、1∶16 000、1∶64 000时免疫反应性均有明显增高。其中稀释度在1∶1 000时增高最明显。OMP18的B细胞抗原表位多肽具有免疫特异性。结论用OMP18的B细胞抗原表位多肽作为包被抗原对空肠弯曲菌感染的血清进行ELISA检测,免疫反应性高,具有免疫特异性。  相似文献   
5.
To acquire essential Fe(III), bacteria produce and secrete siderophores with high affinity and selectivity for Fe(III) to mediate its uptake into the cell. Here, we show that the periplasmic binding protein CeuE of Campylobacter jejuni, which was previously thought to bind the Fe(III) complex of the hexadentate siderophore enterobactin (Kd ∼ 0.4 ± 0.1 µM), preferentially binds the Fe(III) complex of the tetradentate enterobactin hydrolysis product bis(2,3-dihydroxybenzoyl-l-Ser) (H5-bisDHBS) (Kd = 10.1 ± 3.8 nM). The protein selects Λ-configured [Fe(bisDHBS)]2− from a pool of diastereomeric Fe(III)-bisDHBS species that includes complexes with metal-to-ligand ratios of 1:1 and 2:3. Cocrystal structures show that, in addition to electrostatic interactions and hydrogen bonding, [Fe(bisDHBS)]2− binds through coordination of His227 and Tyr288 to the iron center. Similar binding is observed for the Fe(III) complex of the bidentate hydrolysis product 2,3-dihydroxybenzoyl-l-Ser, [Fe(monoDHBS)2]3−. The mutation of His227 and Tyr288 to noncoordinating residues (H227L/Y288F) resulted in a substantial loss of affinity for [Fe(bisDHBS)]2− (Kd ∼ 0.5 ± 0.2 µM). These results suggest a previously unidentified role for CeuE within the Fe(III) uptake system of C. jejuni, provide a molecular-level understanding of the underlying binding pocket adaptations, and rationalize reports on the use of enterobactin hydrolysis products by C. jejuni, Vibrio cholerae, and other bacteria with homologous periplasmic binding proteins.With the rapid rise in bacterial resistance to antibiotics, a better understanding of cooperative behavior in microbial communities is urgently needed for the development of novel approaches to controlling infections caused by resistant bacteria (1, 2). As an essential nutrient, iron is often a growth-limiting factor for beneficial, commensal, and pathogenic bacteria alike, not only due to its low solubility in water under aerobic conditions at and around neutral pH, but also because the host organism and competing microbes actively limit its availability (3, 4). Microorganisms evolved efficient Fe(III) uptake mechanisms to overcome this challenge, a common strategy being the production of siderophores, small Fe(III)-chelating molecules with high affinity and selectivity for Fe(III), with over 500 examples known to date (5). The sharing of siderophores is a recognized example for positive cooperativity that has been linked to bacterial virulence (6). The best-characterized siderophores are hexadentate ligands that form coordinatively saturated, octahedral 1:1 complexes with Fe(III) (3, 5, 7), the most studied being the triscatecholate enterobactin (H6-ENT) produced by many enteric bacteria (8).In Escherichia coli, enterobactin is synthesized within the cell and secreted through the cell membranes to capture Fe(III) from the environment. The resulting Fe(III)-enterobactin complex [Fe(ENT)]3− is recognized by the outer membrane receptor FepA and actively transported into the periplasm. In the periplasm, [Fe(ENT)]3− is sequestered by the periplasmic binding protein (PBP) FepB, which transfers it to an inner membrane transporter for further transport into the cytoplasm (9). Once there, [Fe(ENT)]3− is hydrolyzed by an intracellular esterase to release Fe(III) for use in the cell (8).Along with the development of structurally diverse siderophores, microorganisms adapted their associated receptor and transport proteins for the uptake of the appropriate Fe(III) complexes (9). To gain a competitive advantage, many bacteria have evolved to poach siderophores produced by other bacteria. Campylobacter jejuni, for example, does not itself produce siderophores yet possesses an uptake system that is able to use siderophores from competing species (10). Initially, it was proposed that in C. jejuni [Fe(ENT)]3− is transported across the outer membrane by the receptors CfrA and CfrB (11). Once in the periplasm, [Fe(ENT)]3− was proposed to bind to the PBP CeuE, the resulting complex enabling the transport of the ferric siderophore into the cytoplasm (12, 13).In addition, increasing numbers of lower-denticity siderophores are being isolated from bacterial cultures and found to coordinate Fe(III) and mediate its uptake (1418). For example, the trilactone backbone of enterobactin makes it prone to hydrolysis, and although this lability is necessary to allow the intracellular release of Fe(III) from the siderophore, it in addition leads to its slow degradation in aqueous media (7, 1921). Three hydrolysis products are formed: tris(2,3-dihydroxybenzoyl-l-Ser) (H7-trisDHBS), bis(2,3-dihydroxybenzoyl-l-Ser) (H5-bisDHBS), and 2,3-dihydroxybenzoyl-l-Ser (H3-monoDHBS), with all three found in the growth medium of E. coli (Fig. 1). Although enterobactin, once secreted, is also available to other cells (producers or nonproducers), it can only be used once because Fe(III) release requires its hydrolysis. The enterobactin hydrolysis products, however, could be used again as secondary, lower-denticity siderophores.Open in a separate windowFig. 1.Molecular structure of enterobactin, its hydrolysis products, the siderophore mimic H6-MECAM, and a selection of tetradentate siderophores.It has been demonstrated that the human pathogens C. jejuni (10, 22, 23) and Vibrio cholerae (24), the causes of food poisoning and cholera, respectively, can use enterobactin hydrolysis products for the uptake of Fe(III) from their environment. Both are known not to produce enterobactin.An alternative Campylobacter Fe(III) acquisition model that relies on these linear hydrolysis products was recently proposed based on the finding that Cee, the sole trilactone esterase of C. jejuni and Campylobacter coli, is located in the periplasm, i.e., these bacteria are unable to degrade enterobactin within the cytoplasm (25). The model suggests that, once the Fe(III) complex of enterobactin enters the periplasm, its ester backbone is cleaved by Cee, which is highly efficient in hydrolyzing both the Fe(III) complex and apo-enterobactin. The resulting hydrolysis products, mainly the tetradentate ligand bisDHBS5− and the bidentate ligand monoDHBS3−, are then used to mediate the subsequent transport of Fe(III) into the cytoplasm.The identification of the esterase Cee and in particular the observation that bisDHBS5− can be used independently of enterobactin (25) raise important questions about the siderophore preference of the PBP CeuE and its role in the iron uptake in C. jejuni. By using siderophore mimics, we previously demonstrated that CeuE can bind the Fe(III) complexes of both hexadentate and tetradentate catecholate ligands (26, 27). Our cocrystal structures revealed that CeuE interacts with the coordinatively saturated Fe(III) complex of the hexadentate mimic MECAM6− through electrostatic interactions and hydrogen bonding, whereas it binds the coordinatively unsaturated complex of the tetradentate mimic 4-LICAM4− by recruiting the side chains of two amino acid residues (His227 and Tyr288) to complete the coordination sphere of the Fe(III) center. We established that His227 and Tyr288 are conserved among a subset of related PBPs, including VctP from V. cholerae, and suggested that this subset of PBPs undergo similar structural changes to adapt to the binding of lower-denticity sidero-phores (27). The recent report that V. cholerae most efficiently uses trisDHBS7− and bisDHBS5− for the acquisition of Fe(III) provided a partial confirmation of this prediction (24).Here, we report that CeuE binds [Fe(bisDHBS)]2− with much higher affinity than the Fe(III) complex of enterobactin, reveal the structural basis for this difference in binding strength, and examine key aspects of the relevant Fe(III) coordination chemistry in solution.  相似文献   
6.
目的对2013年北京部分市售整鸡样品中沙门菌和弯曲菌的定量污染水平、沙门菌血清型和弯曲菌种水平分布进行研究。方法 2013年5—7月采集北京市售整鸡样品33份,进行样品中沙门菌和弯曲菌的定量检测,并分别对沙门菌和弯曲菌进行血清分型和种水平鉴定。结果 19个样品检出沙门菌,检出率为57.6%;5个样品检出弯曲菌,检出率为15.2%;阳性样品中沙门菌和弯曲菌平均污染水平分别为119.4 MPN/100g和58.6 CFU/g。分离出的166株沙门菌被鉴定为14种血清型,最常见的为肠炎沙门菌,其次为印第安纳沙门菌。从同一样品中分离到共11种2个以上不同血清型组合的沙门菌,最常见的血清型组合为肠炎-印第安纳沙门菌。结论 2013年5—7月北京部分市售整鸡中沙门菌污染率较高、污染水平严重、血清型复杂。  相似文献   
7.
目的拟研制一种可降低空肠弯曲菌在鸡肠道内定植的全菌灭活疫苗。方法利用一种新的灭活剂H;O;与CuCl;混合物灭活空肠弯曲菌制备油佐剂灭活疫苗,免疫SPF鸡后测定灭活疫苗诱导产生的特异性抗体水平,通过口服攻毒评价疫苗免疫对空肠弯曲菌在鸡盲肠内定植的影响,同时测定盲肠细胞因子在转录水平的变化,以及对盲肠绒毛长度和隐窝深度的影响。结果制备的全菌灭活疫苗免疫SPF鸡后可诱导产生特异性血清IgG和胆汁IgA,但口服攻毒后不能抑制或降低空肠弯曲菌在盲肠内的定植水平,且对免疫鸡的盲肠绒毛长度和隐窝深度无明显影响。测定的鸡盲肠中多数细胞因子在空肠弯曲菌攻毒前与攻毒后1 d的转录水平差异不明显,而在攻毒后10 d明显上升;同日龄样品比较结果显示,部分细胞因子的表达量在佐剂对照组和全菌免疫组较空白对照组明显上调。结论本试验研制的全菌灭活疫苗虽可诱导产生高水平特异性抗体,但不能降低空肠弯曲菌在鸡盲肠内的定植水平,提示空肠弯曲菌在鸡盲肠内的定植机制需深入探究。  相似文献   
8.
Campylobacteriosis is one of the most frequently reported zoonoses worldwide. The well-documented increase in the ciprofloxacin resistance has increased the importance of rapid detection of the resistance. The incidence of ciprofloxacin resistance was investigated using real-time PCR. Identification of one hundred and fifty-eight strains was performed by PCR. Minimum inhibitory concentration (MIC) of ciprofloxacin was determined by Epsilometer test. Following the confirmation of the efficiencies of singleplex real-time PCR methods using two different probes, a cytosine to thymine point mutation at codon 86 was detected by allelic discrimination. Of the 158 strains, 114 (72.2%) were determined to be resistant to ciprofloxacin. The MIC50 and the MIC90 of ciprofloxacin were found to be 8 and ≥32 mg/L, respectively. By real-time PCR, the presence of the mutation was confirmed in all, but one, resistant strains and the absence of the mutation was demonstrated in all, but one, susceptible strains. The rate of resistance is high among C. jejuni strains and ciprofloxacin should not be used in the treatment of such infections in Turkey. A cytosine to thymine mutation is the most frequently detected mechanism for the resistance. Real-time PCR can be used for the quick screening of the resistance.  相似文献   
9.

Background

Leukopenia and thrombocytopenia in a febrile patient are not uncommon and may be a diagnostic clue in patients without an alternative explanation for cytopenias. This has not been reported in Campylobacter jejuni infections.

Methods

A healthy patient with fever, rigors, and an acute diarrheal illness was noted to have a white blood cell count of 2.65 × 109/L and platelet level of 125 × 109/L. Retrospective chart review of all adult C. jejuni stool-positive cases admitted over 1 year revealed leukopenia in 6 of 20 (30%), thrombocytopenia in 5 of 20 (25%), and both in 1 of 20 (5%).

Results

Cytopenias were mild, transient, and not associated with prolonged hospital stay or complications.

Conclusions

Acute C. jejuni infections should be added to the differential diagnosis of acute febrile illnesses that may be associated with leukopenia or thrombocytopenia. Cytopenias can be an important diagnostic clue in febrile illnesses, and their differential is presented.  相似文献   
10.
Provision of safe drinking water in the United States is a great public health achievement. However, new waterborne disease challenges have emerged (e.g., aging infrastructure, chlorine-tolerant and biofilm-related pathogens, increased recreational water use). Comprehensive estimates of the health burden for all water exposure routes (ingestion, contact, inhalation) and sources (drinking, recreational, environmental) are needed. We estimated total illnesses, emergency department (ED) visits, hospitalizations, deaths, and direct healthcare costs for 17 waterborne infectious diseases. About 7.15 million waterborne illnesses occur annually (95% credible interval [CrI] 3.88 million–12.0 million), results in 601,000 ED visits (95% CrI 364,000–866,000), 118,000 hospitalizations (95% CrI 86,800–150,000), and 6,630 deaths (95% CrI 4,520–8,870) and incurring US $3.33 billion (95% CrI 1.37 billion–8.77 billion) in direct healthcare costs. Otitis externa and norovirus infection were the most common illnesses. Most hospitalizations and deaths were caused by biofilm-associated pathogens (nontuberculous mycobacteria, Pseudomonas, Legionella), costing US $2.39 billion annually.  相似文献   
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