ULTRASTRUCTURE OF HELICOBACTER-TROGONTUM IN CULTURE AND IN THE GASTROINTESTINAL-TRACT OF GNOTOBIOTIC MICE

Helicobacter trogontum is a micro-aerophilic urease-positive bacterium that has recently been isolated from the intestinal mucosa of rats. T he purpose of this investigation was to study the ultrastructural deta ils of this micro-organism in both pure culture and in the gastrointes tinal tract of germ-free mice infected with H. trogontum. The micro-or ganism was a fusiform to slightly spiral gram-negative cell, 4-6 mu m long and 0.6-0.7 mu m wide, im with four to seven bipolar sheathed fla gella. The cytoplasm presented several irregular and also globular gra nules. On each side of the polar regions of the cells, there was a hig hly electron-dense band, the `polar membrane'. Coccoidal forms were se en in old cultures. H. trogontum showed several ultrastructural charac teristics of the Helicobacter genus and much resemblance to H. rappini and H. bilis. H. trogontum mainly colonised the large bowel of the gn otobiotic mice where it could be seen in the lumen and also inside the enterocytes. Vacuolation of the ileal epithelial cells, loss of micro villi and pronounced desquamation of the enterocytes of the caecum wer e observed in the bowel colonised by the bacterium. These observations raise the possibility that H. trogontum could cause some harm to the host at least in particular circumstances such as when it colonises th e gastrointestinal tract of a germ-free host.