[Microbiological evaluation of Helicobacter pylori stool antigen detection (HpSA) kit; its specificity and reactivity with coccoid form of H. pylori].

Helicobacter pylori stool antigen detection kit (HpSA) was microbiologically evaluated. All of the 10 strains of H. pylori showed positive result in HpSA test, but other bacteria of 16 species and 18 strains did not. In addition, the coccoid form of 10 H. pylori strains reacted positively with the HpSA kit as well as the helical form, although the OD450 value was slightly lower than that of helical form in 7 out of 10 strains examined. The minimum number of H. pylori showing positive reaction in HpSA test was 7.0 x 10(3) cfu. Feces of both conventional and germ free mice inhibited partially the reaction of H. pylori with HpSA kit, but this decrease in the reactivity was recovered by freeze-thawing of the feces. In contrast, freeze-thawing of the mice feces with H. pylori decreased the sensitivity in HpSA test, but it was also shown that coccoid form had a stronger reactivity than helical form. These results indicate that the HpSA kit is a rapid and useful diagnostic method for detection of H. pylori, particularly its coccoid form, in the fecal specimens.