The best method of detecting prior Helicobacter pylori infection

Abstract

Aim: Prior Helicobacter pylori (H pylori) infection has often been underestimated. These underestimations have misled physicians attempting to determine the significance between H pylori and certain gastrointestinal lesions such as intestinal metaplasia, atrophic gastritis, and gastric cancer. Our study endeavored to detect past H pylori infections accurately, easily, and rapidly with the newly developed immunoblot kit, Helico Blot 2.1.

Methods: Thirty-three patients, including 25 H pylori infected and 8 uninfected cases, were enrolled in our study. All patients received consecutive gastroendoscopic examinations and (13)C-urea breath test (UBT) tests at 6- or 12-mo intervals for up to 4 years. Serum samples were obtained from each patient at the same time. Intragastric H pylori infection was confirmed in accordance with the gold standard. Twenty-five H pylori-infected patients received triple therapies after initial bacterial confirmation, and were successful in eradicating their infections. Serially obtained sera were tested by means of Helico Blot 2.1.

Results: Current infection marker detected by Helico Blot 2.1 was unreliable for representing ongoing H pylori infection. Only 35 and 37 ku antibodies of H pylori had significant seroconversion rates 1 year after having been cured. The seropositive rates of 116 ku (cytotoxin-associated antigen (CagA)) and Helico Blot 2.1 were nearly 100% during 4-year follow-up period. Both CagA antigen and Helico blot 2.1 could serve as indicators of long-term H pylori infection.

Conclusion: Helico Blot 2.1 can detect past H pylori infections for up to 4 years, and is the best method to date for detecting previous long-term H pylori infection.

Figure 1

The nitrocellulose strips of Helico Blot 2.1 representative of immunoblot results: lane 1, positive control; lane 2, negative control; lanes 3-7, serial serum samples of a patient showing positive results.

Figure 2

Fluctuating positive rates of various H pylori-specific antigens and Helico Blot 2.1 in 25 H pylori-infected patients were charted at half- year intervals during a 4-year follow- up period. The CIM was unreliable, because it maintained high positive rates for at least 3 years after H pylori eradication. Thirty-five and thirty-seven kilounits antibodies of H pylori showed significant seroconversion changes at 1 year after bacterial cure. The seropositive rates of 116 ku (CagA) and Helico Blot 2.1 were nearly 100% during the 4-year follow-up period.