I. Ofek

Bio: I. Ofek is an academic researcher. The author has contributed to research in topics: Pilus & Mannose. The author has an hindex of 1, co-authored 2 publications receiving 667 citations.

Adherence of Escherichia coli to human mucosal cells mediated by mannose receptors

Abstract: THE colonisation of bacteria on human mucosal tissues is now recognised as an important step in the infectious process1,2. To colonise mucosal surfaces, the organisms must first bind to the epithelial cells of these tissues, or they are discarded by the host's physico-anatomical defence mechanism (sneezing, coughing, urine flush and so on). The attachment of bacteria to epithelial cells can be demonstrated in vitro3,4 and is probably mediated by surface components of both types of cell5. It was found4,5 that lipoteichoic acid on the surface of group A streptococci is responsible for the attachment of these organisms to oral mucosal cells. For Gram negative organisms, pili mediate their binding to epithelial cells6–9. In a study with Proteus mirabilis it was found10 that the presence of pili is important for the organisms to adhere to both oral and bladder mucosal cells as well as to initiate retrograde infection in experimental animals, probably by enabling the bacteria to adhere and to colonise pelvic epithelial cells11. Nothing is known, however, about the putative receptor sites required for bacterial attachment on the mucosal cell membrane. We present here data indicating that attachment of Escherichia coli to epithelial cells is mediated by mannose (or mannose-like) receptors present on the surface of the latter.

Bacterial Adherence: Adhesin-Receptor Interactions Mediating the Attachment of Bacteria to Mucosal Surfaces

Abstract: Recent studies have indicated that the attachment of bacteria to mucosal surfaces is the initial event in the pathogenesis of most infectious diseases due to bacteria in animals and humans. An understanding of the mechanisms of attachment and a definition of the adhesive molecules on the surfaces of bacteria (adhesins) as well as those on host cell membranes (receptors) have suggested new approaches to the prevention of serious bacterial infections: (1) application of purified adhesion or receptor materials or their analogues as competitive inhibitors of bacterial adherence; (2) administration of sublethal concentrations of antibiotics that suppress the formation and expression of bacterial adhesins; and (3) development of vaccines against bacterial surface components involved in adhesion to mucosal surfaces. Progress has already been made in the development of antiadhesive vaccines directed against the fimbrial adhesins of several human bacterial pathogens.

Virulence factors in Escherichia coli urinary tract infection.

Abstract: Uropathogenic strains of Escherichia coli are characterized by the expression of distinctive bacterial properties, products, or structures referred to as virulence factors because they help the organism overcome host defenses and colonize or invade the urinary tract. Virulence factors of recognized importance in the pathogenesis of urinary tract infection (UTI) include adhesins (P fimbriae, certain other mannose-resistant adhesins, and type 1 fimbriae), the aerobactin system, hemolysin, K capsule, and resistance to serum killing. This review summarizes the virtual explosion of information regarding the epidemiology, biochemistry, mechanisms of action, and genetic basis of these urovirulence factors that has occurred in the past decade and identifies areas in need of further study. Virulence factor expression is more common among certain genetically related groups of E. coli which constitute virulent clones within the larger E. coli population. In general, the more virulence factors a strain expresses, the more severe an infection it is able to cause. Certain virulence factors specifically favor the development of pyelonephritis, others favor cystitis, and others favor asymptomatic bacteriuria. The currently defined virulence factors clearly contribute to the virulence of wild-type strains but are usually insufficient in themselves to transform an avirulent organism into a pathogen, demonstrating that other as-yet-undefined virulence properties await discovery. Virulence factor testing is a useful epidemiological and research tool but as yet has no defined clinical role. Immunological and biochemical anti-virulence factor interventions are effective in animal models of UTI and hold promise for the prevention of UTI in humans. Images

An adhesive factor found in strains of Escherichia coli belonging to the traditional infantile enteropathogenic serotypes

Abstract: Escherichia coli strains isolated from outbreaks of diarrheal disease were tested for the presence of adhesive factors. Fifty-one of these strains belonged to traditional infantile entero-pathogenic serotypes (EPEC) and 17 belonged to other serotypes. None of these strains were enterotoxigenic and none possessed colonization factors CFA/I or CFA/II, which have been described among strains of enterotoxigenicE. coli (ETEC). EnterotoxigenicE. coli strains from patients with diarrhea and strains which were neither EPEC nor ETEC from subjects without diarrhea were also examined. By means of a tissue culture technique using HEp-2 cells, a new adhesive factor was found to occur with greater frequency in EPEC strains. The adhesive factor was found less frequently in the other groups ofE. coli studied. It was distinct from type 1 pili and was not inhibited by the presence ofD-mannose.

An update on alternatives to antimicrobial growth promoters for broilers

Abstract: Livestock performance and feed efficiency are closely interrelated with the qualitative and quantitative microbial load of the animal gut, the morphological structure of the intestinal wall and the activity of the immune system. Antimicrobial growth promoters have made a tremendous contribution to profitability in intensive husbandry, but as a consequence of the increasing concern about the potential for antibiotic resistant strains of bacteria, the European Commission decided to ban all commonly used feed antibiotics. There are a number of non-therapeutic alternatives, including enzymes, (in)organic acids, probiotics, prebiotics, etheric oils and immunostimulants. Their efficacy and mode of action are briefly described in this review.