Different roles of host and bacterial factors in Escherichia coli extra-intestinal infections

Many host and bacterial factors contribute to the development of different Escherichia coli extra-intestinal infections. The aim of this study was to evaluate the roles of host and bacterial factors in different extra-intestinal E. coli infections. A total of 221 E. coli isolates collected from urine, bile and peritoneal fluid were included in this retrospective study. Four main phylogenetic groups of E. coli , 14 genetic determinants, static biofilm formation and antimicrobial resistance data were assessed, as well as the immunological status of the hosts. Group B2 was the most common phylogenetic group (30%), especially in cases of asymptomatic bacteriuria (ABU), urinary tract infection (UTI), acute appendicitis/gastrointestinal perforation, and spontaneous bacterial peritonitis (SBP), and was associated with elevated prevalence of papG  III , fimH , sfa , iha , hlyA , cnf1 , ompT and usp . Phylogenetic group A was most common in the isolates from asymptomatic bacteriocholia, biliary tract infection, and peritoneal dialysis (PD)-related peritonitis. There was similarity with respect to both phylogenetic groups and virulence factors in strains from faeces and ABU, and in strains from faeces and SBP/PD-related peritonitis. Host characteristics were important in patients with ABU, UTI, and SBP/PD-related peritonitis. Immunocompetence of hosts was associated with a relatively high prevalence of papG  II , afa and iha , and relatively low antimicrobial resistance to fluoroquinolones. This study demonstrates that, in most E. coli extra-intestinal infections, phylogenetic group B2 was predominant and was more virulent than the three other phylogenetic groups in the Taiwanese population studied. The diverse patterns of host and bacterial factors demonstrate that there were different host and bacterial factors dominating in different extra-intestinal E. coli infections.     

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??Objective    To compare the biofilm formation of P. gingivalis  W83 and its sialidase-deficient mutant strain??ΔPG0352?? under stressful conditions. Methods    P. gingivalis  W83 and ΔPG0352 were cultured in trypticase soy broth??TSB??and supplemented with 5 μg/mL hemin and 1 μg/mL menadione under stressful conditions??including temperature??oxidatie stress and pH values. Biofilms were formed on the 96-well plates for four days??and stained with crystal violet. Detect the biofilm formation with spectrophotometer. Results    Both P. gingivalis  W83 and ΔPG0352 strains could form biofilms in normal culture conditions. P. gingivalis  W83 formed more biofilm??compared to ?PG0352 ??P < 0.05??. The biofilm formations of P. gingivalis  W83 and ΔPG0352 decreased in 34?? and 41?? ??P < 0.05??. As the concentration of H2O2 increased??biofilm formations of both strains decreased more and more seriously. The biofilm formations of ΔPG0352 were less than those of P. gingivalis  W83??when the ultimate concentration of hydrogen peroxide was 0.1??0.25 and 0.5 mmol/L. Both P. gingivalis  W83 and ?PG0352 formed less biofilm in alkaline condition??pH = 9????ΔPG0352 even less??and were unable to form biofilm in acidic condition??pH = 5??. Conclusion    Sialidase gene deletion can affect P. gingivalis  biofilm formation. Biofilms formations of both P. gingivalis  W83 and ΔPG0352 will decrease under stressful conditions.      

Host structural carbohydrate induces vector transmission of a bacterial plant pathogen

Many insect-borne pathogens have complex life histories because they must colonize both hosts and vectors for successful dissemination. In addition, the transition from host to vector environments may require changes in gene expression before the pathogen''s departure from the host. Xylella fastidiosa is a xylem-limited plant-pathogenic bacterium transmitted by leafhopper vectors that causes diseases in a number of economically important plants. We hypothesized that factors of host origin, such as plant structural polysaccharides, are important in regulating X. fastidiosa gene expression and mediating vector transmission of this pathogen. The addition of pectin and glucan to a simple defined medium resulted in dramatic changes in X. fastidiosa''s phenotype and gene-expression profile. Cells grown in the presence of pectin became more adhesive than in other media tested. In addition, the presence of pectin and glucan in media resulted in significant changes in the expression of several genes previously identified as important for X. fastidiosa''s pathogenicity in plants. Furthermore, vector transmission of X. fastidiosa was induced in the presence of both polysaccharides. Our data show that host structural polysaccharides mediate gene regulation in X. fastidiosa, which results in phenotypic changes required for vector transmission. A better understanding of how vector-borne pathogens transition from host to vector, and vice versa, may lead to previously undiscovered disease-control strategies.     

Analysis of Streptococcus mutans biofilm proteins recognized by salivary immunoglobulin A

Introduction:  The purpose of this study was to examine the Streptococcus mutans biofilm cellular proteins recognized by immunoglobulin A (IgA) in saliva from various caries-defined populations.
Methods:  Biofilm and planktonic S. mutans UA159 cells were prepared. The proteins were extracted, separated by two-dimensional gel electrophoresis, transferred to blotting membranes, and probed for IgA using individual saliva samples from three groups of subjects; those who developed 0 caries (no active caries), 5–9 caries (medium), or more than 10 caries (severe) over a 12-month interval.
Results:  Several proteins were recognized by salivary IgA in all groups of saliva but spot distribution and intensity varied greatly between the groups, and some proteins were recognized more strongly in biofilm cells than in planktonic culture, and vice versa. Furthermore, 15 proteins were only recognized by saliva from the 'no active caries' group, and four proteins were recognized by saliva samples from subjects in all three groups. Specifically, antigen I/II was recognized less in biofilm cells by caries-free saliva compared with planktonic cells. However, salivary IgA antibody to antigen I/II was absent in blots using saliva from the 'medium caries' and 'severe caries' groups.
Conclusion:  The bacterial molecules recognized by caries-free saliva are significant factors for S. mutans caries formation, and their inhibition could be a therapeutic target. In addition, saliva of caries-free subjects includes significant IgA antibody against antigen I/II of S. mutans , indicating a protective mechanism. However, microorganisms may protect themselves from host immune attack by forming biofilms and decreasing expression of antigen I/II.     

Triclosan-loaded poloxamine micelles for enhanced topical antibacterial activity against biofilm

Our research group is interested in the study of different technological approaches to treat hospital biofilm as a means to constrain nosocomial-acquired infections. The present work investigated the effect of the incorporation of the antibacterial agent triclosan (TS) into polymeric micelles of poloxamine T1107 (MW=15 kDa, 70 wt% PEO). The aggregation phenomenon was primarily investigated by means of Critical Micellar Concentration in a broad range of pH. Then, the effect of the polymer concentration on the micellar size was evaluated by Dynamic Light Scattering. Solubility levels increased up to 4 orders of magnitude. The drug inclusion affected the micellization, resulting in size increase and micellar fusion. This phenomenon was only apparent in TS-saturated systems. TS-loaded aggregates proved to be active in vitro against a broad spectrum of bacteria but more importantly, also against two representative clinical pathogens: methicilin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant Enterococcus faecalis (VREF). While the former was sensitive to even very low TS levels attainable in poloxamine-free aqueous media, the later was inhibited only when exposed to higher drug levels affordable exclusively using an inclusion system. These findings indicated the release of the drug from the reservoir. Finally, the activity of a TS-containing 5% poloxamine combination of pH 7.4 was assessed on biofilms of Staphylococcus epidermidis. Results showed a significant decrease (p<0.001) in the number of Colony-Formation Units when the biofilm was exposed to the TS/poloxamine as compared to the limited activity of the polymer-free TS control.     

Efficacy of an amine fluoride-triclosan mouthrinse as compared to the individual active ingredients

BACKGROUND: The purpose of the clinical study was to examine the antibacterial and plaque-reducing properties of mouthrinses containing triclosan (TRI), amine fluoride (AmF), and the combination of both (AFT) on 4-day plaque regrowth. A placebo solution (PLA) and a 0.2% chlorhexidine solution (CHX) served as negative and positive controls, respectively. MATERIALS AND METHODS: After a professional tooth cleaning (day 0), 15 volunteers refrained from all mechanical oral hygiene measures for the next 96 h and rinsed instead twice daily for 1 min with 10 ml of one of the five randomly assigned solutions. Plaque index (PlI), which was assessed after 24 and 96 h (PlI1, PlI2), and plaque area of the front teeth (PA), which was planimetrically recorded from disclosed teeth after 96 h, served as clinical parameters. After 24 and 96 h a plaque sample was taken and analyzed microbiologically to evaluate biofilm vitality (VF1, VF2). The subsequent test cycles were conducted after a washout period of 10 days each. RESULTS: No severe adverse events or allergy were seen during the study. CHX influenced all parameters at all time points in comparison to PLA. AFT and AmF showed very similar values (in all parameters), but AmF did not reach the level of significance regarding VF1, nor did AFT with VF2 and PlI1. The TRI solution only reduced PlI2 and PA significantly, but had no influence on biofilm vitality when compared to PLA. CONCLUSION: A synergism between AmF and TRI was not observed. The results suggest that the plaque-reducing and antibacterial effects of the AFT solution are mainly based on the effects of the amine fluoride moiety.     

颗粒型生物膜反应器在污水处理中的应用

介绍了颗粒型生物膜反应器在污水处理中的应用情况,对比了不同反应器结构和技术特点.与传统的活性污泥法和静态生物膜反应器相比,颗粒型生物膜反应器具有沉降速度快、污泥浓度高、比表面积大等特点,可以达到很高的负荷,节省占地面积.另外,颗粒型生物膜反应器的污泥产率也非常低、不存在污泥膨胀的问题,日常维护也非常简单.并指出随着对该领域进一步的深入研究和新型反应器的开发,颗粒型生物膜反应器将得到更为广泛的应用.     

阿奇霉素对铜绿假单胞菌生物被膜的抑制作用

目的研究阿奇霉素对铜绿假单胞茵生物被膜的抑制作用。方法将阿奇霉素标准品用生理盐水配成不同的浓度，与培养的铜绿假单胞茵生物被膜作用，6d后用扫描电镜观察生物被膜的情况。结果未用阿奇霉素的硅胶片上可见较厚的生物被膜形成，而应用阿奇霉素后可见生物被膜较对照组薄且有碎裂，其变化与阿奇霉素的浓度相关。结论阿奇霉素可能抑制铜绿假单胞茵生物被膜的形成。     

氨溴索对铜绿假单胞菌生物膜结构的影响

目的 建立铜绿假单胞菌生物膜(biofilm,BF)模型,探讨氨溴索对粘液型铜绿假单胞菌成熟BF的结构影响.方法 平板培养法培养铜绿假单胞菌7 d,得到成熟BF,用扫描电镜(scannmg electron microscope,SEM)观察氨溴索对BF形态结构的影响;激光共聚焦显微镜(confocal laser scanning microscopy,CLSM)结合BF图像结构分析软件(image structure analyer,ISA)对BF结构参数分析;荧光显微镜定性观察氨溴索对BF内活菌的作用,并测定氨溴索单独作用以及与环丙沙星联用后BF内活菌的荧光强度.结果 氨溴索作用后电镜观察可见BF被破坏,基质样物变稀疏,仅见少量散在细菌.ISA软件定量分析显示:2 mg/ml氨溴索作用后,BF厚度、平均扩散距离(average diffusion distance,ADD)和结构熵(textual entropy,TE)均减少(P＜0.05);区域孔率(areal porosity,AP)增加(P＜0.05).0.75 mg/ml氨溴索干预后,有同样趋势,但效应不如高浓度明显.用荧光显微镜定性观察,当氨溴索浓度大于0.49 mg/ml时,BF内活菌数减少.同时,氨溴索与环丙沙星存在协同作用(F=15.1,P＜0.05),且随着氨溴索浓度升高,协同作用增强.结论 氨溴索可影响铜绿假单胞菌成熟BF形态结构,从而增强抗生素的杀菌活性.