Salmonella interactions with polarized human intestinal Caco-2 epithelial cells

Article Abstract:

The adherence to and penetration of barriers of host epithelial cells is a property of many human pathogens, such as species of the Brucella, Chlamydia, Listeria, Neisseria, Shigella, Yersinia and Salmonella bacteria, as well as many viruses and parasites. The study of the invasive properties of these organisms has been hindered by the, hitherto, lack of available cellular models that approximate the formation of a brush border, and other properties and organized features of tissue. Recent cell technology has facilitated the growth of epithelial cell lines as impermeable polarized monolayers. The cell surface adherent to the collagen-treated permeable filter forms the basolateral surface. The nonadherent surface is described as the apical surface. One of three human adenocarcinoma cell lines, Caco-2, has been shown to develop well defined brush borders, and form polarized monolayers; both properties resemble human intestinal epithelium. Salmonella species express pathogenicity, among other properties, by invading cells of the gastric mucosa. This report, accompanied by extensive and detailed electron microphotographs, describes and follows, in detail, the sequential events of cellular invasion by Salmonella species. These morphologic observations correlate well with results obtained in studies using animal models. This in-vitro system, which utilizes polarized human intestinal Caco-2 cells (PHICaco2), will be useful in the study of pathogens that interact with intestinal epithelial tissue and cause disease manifestations. (Consumer Summary produced by Reliance Medical Information, Inc.)

Physiological aspects, Salmonella, Epithelial cells, Histology, Pathological, Pathological histology

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Detection of Shigella in feces using DNA amplification

Article Abstract:

Asubstantial number of bacillary dysentery cases are due to infection with the Shigella species, and result in endemic situations and frequent epidemics in the developing countries. The organisms produce diarrhea by invasion of the colon. This action is mediated by a plasmid (a subcellular component outside the nucleus that has a genetic function) that carries the determinants that code invasion by each of the Shigella species and the related enteroinvasive Escherichia coli strain (EIEC). Identification of isolates of Shigella in the feces is usually accomplished by culture and biochemical test responses. A new procedure, polymerase chain reaction (PCR), when applied to Shigella identification eliminates the need for biochemical testing. Following growth on solid media, colonies were analyzed by DNA hybridization. DNA sequences were identified that were specific for Shigella species and all tested EIEC isolates. Analyses of these sequences resulted in the development of a test process using PCR for identification of the organisms without a requirement for in vitro cultivation. This process can provide results on the same day the specimens are received. The advantage of a quick test turnaround is obvious in the cases of institutional outbreaks and disasters. There are disadvantages, which have yet to be reconciled, including the fact that the procedure does not distinguish between species of the Shigella nor EIEC from Shigella. (Consumer Summary produced by Reliance Medical Information, Inc.)

Medical examination, Identification and classification, Polymerase chain reaction, Feces, Shigella

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The microbe's view of infection

Article Abstract:

In may be inappropriate to think that humans can conquer all infectious diseases. Many so-called new infectious diseases are really caused by old organisms that have found a new niche. Sometimes changes in technology can cause this, as aerosolizing water led to outbreaks of Legionella. Humans are colonized by hundreds of bacterial species, many of which play important functions. However, a benign bacterium can become deadly if it acquires a gene for drug-resistance from another bacterial species.

Editorial, Analysis, Bacterial infections

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