Background/aims: We measured the levels of IgG antibody in patients treated for H. pylori infection using four commercially available ELISA (enzyme linked immunosorbent assay) kits.
Methodology: A total of 37 patients with peptic ulcers (21 patients had gastric ulcers and 16 patients had duodenal ulcers) were treated and monitored. These patients were treated for 14 days with either a dual therapy regime consisting of amoxicillin at 1,500 mg per day and omeprazole at 20 mg per day or a triple therapy regime consisting of the same medications as above plus metronidazole at 1,000 mg per day. Of these 37 patients, 24 patients (64.9%) had successful eradication of the H. pylori infection. The other 13 patients (35.5%) remained infected. Infection by H. pylori was confirmed prior to treatment using conventional microbiological (rapid urease test) and histological tests on biopsy specimens obtained by endoscopy. Four commercially available ELIZA kits (GAP-IgG, Hel-P, Helico-G and HM-CAP) were used to measure the serum levels of IgG antibody against H. pylori before treatment and at 3, 6 and 9 months after treatment. A significant decrease in the IgG titer was observed with the successful eradication of the H. pylori infection.
Results: In patients whom the H. pylori infection was not eradicated, the IgG titer remained the same throughout the testing period. All the kits showed a significant decrease in the IgG levels (approximately 50% at 3 months) with patients that were successfully treated. The HM-CAP kit had the lowest sensitivity at detection the decrease in antibody levels (approximately 42% decrease at 3 months). The GAP-IgG kit was able to detect whether or not H. pylori was eradicated in shortest time period (100% uniformity ratio at 3 months).
Conclusions: The results of this study suggest that monitoring serum IgG levels after treatment may provide an early indicator of the efficacy of therapy in eradicating H. pylori infection. Additionally, the serum IgG level can provide evidence of infection in chronic gastritis patients even when the biopsy specimens are negative by microbiological and/or histological tests.