Summary auto-generated
Researchers examined the ultrastructure of a previously undescribed spiral bacterium found in pig gastric mucosa using electron microscopy. The organism, located in mucus on the antral pit surface, measured approximately 4.0 micrometers long and 0.6 micrometers wide with 3-8 spiral turns and truncated ends. Transmission electron microscopy revealed up to six flagella arising from each pole, a gram-negative cell wall, cytoplasmic ribosomes, and distinctive membrane-bound granules. A highly electron-dense "polar membrane" was observed at the flagella insertion sites. Unlike spiral bacteria found in cats, dogs, and monkeys that colonize fundic glands without causing pathological changes, this pig bacterium colonized the antral mucosa and induced antral gastritis, similar to Helicobacter pylori infection in humans. The organism shared morphological properties with H. pylori including spiral shape, high urease activity, and shallow glandular penetration. The authors propose the name "Gastrospirillum suis" for this bacterium. Given that morphologically similar spirals have been observed in human gastric biopsies from gastritis patients, this pig model may provide insights into human gastric spiral bacterial infections and their pathogenic mechanisms.
Key findings
- A novel spiral bacterium from pig stomach, designated "Gastrospirillum suis," measures 4.0 micrometers long with 3-8 spiral turns and possesses up to six flagella per pole, distinguished by a characteristic polar membrane structure.
- Unlike spiral bacteria in other animals, the pig organism colonizes antral mucosa and causes antral gastritis similar to Helicobacter pylori infection in humans.
- The bacterium shares key properties with H. pylori including gram-negative morphology, high urease activity, and shallow penetration into gastric glands without deeply invading tissues.
- Morphologically similar spiral bacteria have been observed in human gastric biopsies from gastritis patients, suggesting pigs may be a potential zoonotic source.
- The pig bacterium differs ultrastructurally from gastric spirals in cats, dogs, and monkeys, lacking periplasmic fibrils and possessing unique membrane-bound granules with electron-dense cores.
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Abstract
The ultrastructural features of a helical-shaped bacterium occurring in the stomach of pigs, within the mucus on the mucosal surface of antral pits, were examined. The bacterial cell had three to eight spiral turns, flattened and truncated ends and was approximately 4.0 microns long and 0.6 microns wide. In some sections, up to six flagella, about 22 nm in diameter, were seen arising from each pole. The cytoplasm contained sparse, irregular granules, numerous ribosomes and large single-layered membrane-bound granules. In the flagella insertion area, there was a highly electron-dense component, the "polar membrane". This micro-organism differed from similar bacteria described in cats, dogs and monkeys, and may cause inflammation in the antral mucosa of pigs similar to Helicobacter pylori infection in man. Furthermore, it was morphologically similar to the spiral micro-organism distinct from H. pylori which has been described recently in human antral mucosa from patients with gastritis and may be of potential significance as a pathogen in man. The name "Gastrospirillum suis" is proposed for this bacterium.