[Objective] In Japan, mortality due to gastric cancer has not changed much over the past 35 years and is around 50,000 annually. The relationships between Helicobacter pylori (HP) and gastric cancer has become known since the discovery of HP in 1983. It has been reported that eradication of HP reduces the incidence of gastric cancer by approximately 33%. For early detection of HP, our hospital plans to introduce a latex immunoturbidimetric assay. Therefore, we investigated the usefulness of new reagents for the latex immunoturbidimetric assay.
 [Subjects and Methods] The subjects were volunteers who underwent endoscopy as part of complete medical examination at our hospital in August and September 2016. An automatic analyzer (LABOSPECT 008, Hitachi) was used to analyze the collected serum samples and three newly developed reagents for latex immunoturbidimetric assay were compared. Measurement was outsourced and performed by the conventional ELISA method if there were discrepancies between the endoscopy findings and the results of serum anti-HP antibody measurement.
 [Results and Discussion] Endoscopy was performed in 148 volunteers. The result was HP-negative in 95 volunteers and HP-positive (current infection) in six volunteers, while 47 volunteers were determined to have previous HP infection (including those who had received HP eradication therapy). Of the 95 HP-negative volunteers, anti-HP antibodies were negative in 85 (91.6%) using Reagent A, in 91 (95.8%) using Reagent B, and in 86 (90.5%) using Reagent C. Among the six HP-positive volunteers, anti-HP antibodies were positive in all six (100%) using Reagent A, in four (66.7%) using Reagent B, and in six (100%) using Reagent C. Among the 47 volunteers with previous HP infection, anti-HP antibodies were positive in 29 (61.7%) using Reagent A, in seven (14.9%) using Reagent B, and in 22 (46.8%) using Reagent C. In the volunteers with positive endoscopy results or past infection, the anti-HP antibody-positive rate differed among the three reagents. However, the results obtained with Reagent A or Reagent C were highly consistent with the endoscopy findings. This suggests that measurement of anti-HP antibody using a latex immunoturbidimetric assay is useful for early detection of HP.