Gastrospirillum hominis and Helicobacter pylori infection in Thai individuals: comparison of histopathological changes of gastric mucosa.

The presence of Helicobacter pylori (H. pylori) in the stomach is closely associated with histological signs of chronic active gastritis and peptic ulcer. Another spiral organism named Gastrospirillum hominis (G. hominis) has led to further interest in the bacterial pathogenesis of gastritis. Due to the low prevalence of G. hominis, it is difficult to evaluate its biological behavior. Recently 16 cases of G. hominis-associated gastritis were found in 257 Thai individuals, which made it possible to study the biological characteristics of G. hominis and its relationship with gastric mucosal inflammation. The results showed that H. pylori and G. hominis could be easily observed in the lower third of the mucous layer and in the mucosa of the gastric pits by means of toluidine blue staining. Both bacteria immunostained positive. Helicobacter pylori were usually in the shape of curved bacillary while G. hominis often appeared in spiral configuration. In 257 cases of Thai subjects, 169 cases were found to be H. pylori positive, the detection rate was 65.7%, and 16 cases were G. hominis positive, with a 6.2% detection rate. In G. hominis infection, 43.6% of cases had normal gastric mucosa. Superficial, erosive and atrophic gastritis cases were 13.2, 10.9 and 12.5%, respectively. Mucosal inflammation was usually severe in H. pylori, but neutrophil polymorph infiltration was often mild and focal in G. hominis infection. Although no G. hominis infection with carcinoma was shown in our cases, the occurrence of mucosal atrophy, metaplasia and dysplasia was higher in both bacterial infections compared with H. pylori- and G. hominis-negative cases. It is suggested that G. hominis may be partly responsible for the mucosal inflammation and some malignant-associated lesions.