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Uropathogenic E. Coli (uropathogenic + e._coli)
Selected AbstractsEscherichia coli mediated urinary tract infections: Are there distinct uropathogenic E. coli (UPEC) pathotypes?FEMS MICROBIOLOGY LETTERS, Issue 2 2005Carl F. Marrs Abstract A variety of virulence genes are associated with Escherichia coli mediated urinary tract infections. Particular sets of virulence factors shared by bacterial strains directing them through a particular pathogenesis process are called a "pathotype." Comparison of co-occurrence of potential urinary tract infection (UTI) virulence genes among different E. coli isolates from fecal and UTI collections provides evidence for multiple pathotypes of uropathogenic E. coli, but current understanding of critical genetic differences defining the pathotypes is limited. Discovery of additional E. coli genes involved in uropathogenesis and determination of their distribution and co-occurrences will further define UPEC pathotypes and allow for a more detailed analysis of how these pathotypes might differ in how they cause disease. [source] The affinity of the FimH fimbrial adhesin is receptor-driven and quasi-independent of Escherichia coli pathotypesMOLECULAR MICROBIOLOGY, Issue 6 2006Julie Bouckaert Summary Type-1 fimbriae are important virulence factors for the establishment of Escherichia coli urinary tract infections. Bacterial adhesion to the high-mannosylated uroplakin Ia glycoprotein receptors of bladder epithelium is mediated by the FimH adhesin. Previous studies have attributed differences in mannose-sensitive adhesion phenotypes between faecal and uropathogenic E. coli to sequence variation in the FimH receptor-binding domain. We find that FimH variants from uropathogenic, faecal and enterohaemorrhagic isolates express the same specificities and affinities for high-mannose structures. The only exceptions are FimHs from O157 strains that carry a mutation (Asn135Lys) in the mannose-binding pocket that abolishes all binding. A high-mannose microarray shows that all substructures are bound by FimH and that the largest oligomannose is not necessarily the best binder. Affinity measurements demonstrate a strong preference towards oligomannosides exposing Man,1-3Man at their non-reducing end. Binding is further enhanced by the ,1-4-linkage to GlcNAc, where binding is 100-fold better than that of ,- d -mannose. Man,1-3Man,1-4GlcNAc, a major oligosaccharide present in the urine of ,-mannosidosis patients, thus constitutes a well-defined FimH epitope. Differences in affinities for high-mannose structures are at least 10-fold larger than differences in numbers of adherent bacteria between faecal and uropathogenic strains. Our results imply that the carbohydrate expression profile of targeted host tissues and of natural inhibitors in urine, such as Tamm-Horsfall protein, are stronger determinants of adhesion than FimH variation. [source] Physical Properties of Biopolymers Assessed by Optical Tweezers: Analysis of Folding and Refolding of Bacterial PiliCHEMPHYSCHEM, Issue 2 2008Magnus Andersson Abstract Bacterial adhesion to surfaces mediated by specific adhesion organelles that promote infections, as exemplified by the pili of uropathogenic E. coli, is studied mostly at the level of cell,cell interactions and thereby reflects the averaged behavior of multiple pili. The role of pilus rod structure has therefore only been estimated from the outcome of experiments involving large numbers of organelles at the same time. It has, however, lately become clear that the biomechanical behavior of the pilus shafts play an important, albeit hitherto rather unrecognized, role in the adhesion process. For example, it has been observed that shafts from two different strains, even though they are similar in structure, result in large differences in the ability of the bacteria to adhere to their host tissue. However, in order to identify all properties of pilus structures that are of importance in the adhesion process, the biomechanical properties of pili must be assessed at the single-molecule level. Due to the low range of forces of these structures, until recently it was not possible to obtain such information. However, with the development of force-measuring optical tweezers (FMOT) with force resolution in the low piconewton range, it has lately become possible to assess forces mediated by individual pili on single living bacteria in real time. FMOT allows for a more or less detailed mapping of the biomechanical properties of individual pilus shafts, in particular those that are associated with their elongation and contraction under stress. This Mi- nireview presents the FMOT technique, the biological model system, and results from assessment of the biomechanical properties of bacterial pili. The information retrieved is also compared with that obtained by atomic force microscopy. [source] Risk factors for extended-spectrum ,-lactamase positivity in uropathogenic Escherichia coli isolated from community-acquired urinary tract infectionsCLINICAL MICROBIOLOGY AND INFECTION, Issue 2 2010Ö. K. Azap Clin Microbiol Infect 2010; 16: 147,151 Abstract The aim of this prospective cohort study was to determine the risk factors for community-acquired urinary tract infections (UTIs) caused by extended-spectrum ,-lactamase (ESBL)-positive Escherichia coli and the distribution of the ESBL enzyme types. Structured forms were filled in for patients diagnosed with community-acquired UTI in four different geographical locations in Turkey. The forms and the isolates were sent to the central laboratory at Baskent University Hospital, Ankara. Antimicrobial susceptibility was determined according to the CLSI criteria. PCR and DNA sequencing were used to characterize the blaTEM, blaCTX-M and blaSHV genes. Multivariate analysis was performed using logistic regression. A total of 510 patients with UTI caused by Gram-negative bacteria were included in this study. ESBLs were detected in 17 of 269 (6.3%) uropathogenic E. coli isolates from uncomplicated UTIs and 34 of 195 (17.4%) E. coli isolates from complicated UTIs (p <0.001). According to multivariate analysis, more than three urinary tract infection episodes in the preceding year (OR 3.8, 95% CI 1.8,8.1, p <0.001), use of a ,-lactam antibiotic in the preceding 3 months (OR 4.6, 95% CI 2.0,0.7, p <0.001) and prostatic disease (OR 9.6, 95% CI 2.1,44.8, p 0.004) were found to be associated with ESBL positivity. The percentages of isolates with simultaneous resistance to trimethoprim,sulphamethoxazole, ciprofloxacin and gentamicin were found to be 4.6% in the ESBL-negative group and 39.2% in the ESBL-positive group (p <0.001). Forty-six of 51 ESBL-positive isolates (90.2%) were found to harbour CTX-M-15. Therapeutic alternatives for UTI, particularly in outpatients, are limited. Further clinical studies are needed to guide the clinicians in the management of community-acquired UTIs. [source] | ||||||||||