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Category: Bacterial Pathogenesis
Other Gastric Helicobacters and Spiral Organisms, Page 1 of 2
< Previous page | Next page > /docserver/preview/fulltext/10.1128/9781555818005/9781555812133_Chap44-1.gif /docserver/preview/fulltext/10.1128/9781555818005/9781555812133_Chap44-2.gifAbstract:
The discovery of Helicobacter pylori changed forever our perception of the stomach as a habitat for specialized bacteria. It is now known that the stomachs of all animals are colonized by a wide range of highly adapted bacteria that belong to the genus Helicobacter. This chapter describes non-H. pylori gastric bacteria and considers the nature of these specialized adaptations that allow this very interesting group of organisms to inhabit the hostile gastric environment where no others can survive. It has been reported that the spiral organisms inhabited the gastric pits of the pyloric and fundic glands, with some of these bacteria closely associated with the acid-producing parietal cells and in some cases inside the canuliculi of these cells. Many of the in vivo culture techniques that were undertaken earlier are still widely used today, especially for the isolation and characterization of gastric helicobacters that have been unable to be cultivated in vitro, a classic example being ''H. heilmannii’’. New and more sophisticated techniques, especially in the field of molecular biology, have led to the discovery of many new organisms that inhabit the stomach, lower bowel, and liver. Like many of the other gastric helicobacters, H. heilmannii is free living and does not attach to the epithelial cell layer. In their natural host, most of the known gastric helicobacters do not induce a significant pathology. Just as the human has H. pylori inhabiting the stomach, most animal species have their own gastric helicobacters, many of which are described in this chapter.
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“Helicobacter heilmannii” in (A) the gastric mucosa of a mouse and (B and C) the canaliculi of a rat parietal cell. Arrows indicate the position of the bacterium.
“Helicobacter heilmannii” in (A) the gastric mucosa of a mouse and (B and C) the canaliculi of a rat parietal cell. Arrows indicate the position of the bacterium.
Electron micrographs of H. felis. (A) Freeze-fracture preparation; arrow indicates the periplasmic fibrils (photo courtesy of S. Kouprach). (B) Negatively stained preparation; arrow indicates the periplasmic fibrils. (C) H. felis colonizing the gastric mucosa of a germ-free mouse (photo courtesy of J. O'Rourke).
Electron micrographs of H. felis. (A) Freeze-fracture preparation; arrow indicates the periplasmic fibrils (photo courtesy of S. Kouprach). (B) Negatively stained preparation; arrow indicates the periplasmic fibrils. (C) H. felis colonizing the gastric mucosa of a germ-free mouse (photo courtesy of J. O'Rourke).
Electron micrographs of H. mustelae. (A) H. mustelae colonizing the gastric mucosa of the ferret. Arrow indicates organisms adhering to the epithelial cell layer and partial endocytosis. (B) Negatively stained preparation of H. mustelae. (Photos courtesy of J. O'Rourke.)
Electron micrographs of H. mustelae. (A) H. mustelae colonizing the gastric mucosa of the ferret. Arrow indicates organisms adhering to the epithelial cell layer and partial endocytosis. (B) Negatively stained preparation of H. mustelae. (Photos courtesy of J. O'Rourke.)
Negatively stained preparations of (A) H. bizzozeronii, magnification × 18,000, and (B) H. salomonis, magnification × 18,000 (photos courtesy of K. Jalava).
Negatively stained preparations of (A) H. bizzozeronii, magnification × 18,000, and (B) H. salomonis, magnification × 18,000 (photos courtesy of K. Jalava).