Autoimmune thyroid diseases and Helicobacter pylori: the correlation is present only in Graves's disease.

AIM: To investigate the correlation between autoimmune thyroid diseases (ATDs) and the prevalence of Cag-A positive strains of Helicobacter pylori (H. pylori) in stool samples. METHODS: Authors investigated 112 consecutive Caucasian patients (48 females and 4 males with Graves' disease and 54 females and 6 males with Hashimoto's thyroiditis HT), at their first diagnosis of ATDs. Authors tested for H. pylori in stool samples using an amplified enzyme immunoassay and Cag-A in serum samples using an enzyme-linked immunoassay method (ELISA). The results were analyzed using the two-sided Fisher's exact test and the respective odds ratio (OR) was calculated. RESULTS: A marked correlation was found between the presence of H. pylori (P ≤ 0.0001, OR 6.3) and, in particular, Cag-A positive strains (P ≤ 0.005, OR 5.3) in Graves' disease, but not in Hashimoto's thyroiditis, where authors found only a correlation with Cag-A strains (P ≤ 0.005, OR 8.73) but not when H. pylori was present. CONCLUSION: The marked correlation between H. pylori and Cag-A, found in ATDs, could be dependent on the different expression of adhesion molecules in the gastric mucosa.

Identification of a correlation between Helicobacter pylori infection and Graves' disease.

BACKGROUND: Viral and bacterial antigens have been suspected to be able to mimic the antigenic profile of the thyroid cell membrane and to play an important role in the onset of the autoimmune diseases, such as Graves' disease and Hashimoto thyroiditis. The Helicobacter pylori infection is worldwide diffused and is present in the developed countries up to 50% of the population. The presence of the cytotoxin-associated gene A antigens identifies the most virulent strains of the bacterium. Previous studies have demonstrated the possible correlation between the Helicobacter pylori and Hashimoto's thyroiditis but these results are controversial. AIMS: We studied the prevalence rate of this bacterium in the Graves' disease and two selected subgroups such as the hyperthyroid patients, at the first time of diagnosis, and the euthyroid methimazole-treated patients. MATERIALS AND METHODS: We analyzed Helicobacter pylori in fresh stool samples with an enzyme immunoassay method and the presence of cytotoxin-associated gene A antigens with a serological test. RESULTS: Our results show that a significative increased rate of prevalence is present in Graves' patients, when the disease is ongoing, with an overall prevalence of the strains expressing the cytotoxin-associated gene A antigens compared to the control group. CONCLUSIONS: The association between the Helicobacter pylori and Graves' disease suggests a possible role of this bacterium in the onset and/or the maintenance of the disease.