Use of reagent to detect fecal microbiota in preparation of detection kit for assistance in predicting risk of gastric cancer

Abstract

This invention relates to the use of a reagent for detecting fecal microbiota in the preparation of a test kit for assisting in the prediction of gastric cancer risk. It utilizes a primer pair with a specific sequence of the reagent to detect and compare the types and abundance of indicator bacteria in the microbiota, which can help determine whether subjects before and after Helicobacter pylori eradication are classified into a low-risk or high-risk group for gastric cancer, and is thus used in the preparation of a test kit for assisting in the prediction of gastric cancer risk.

Claims

1. Use of a reagent for detecting fecal microbiota in the preparation of a test kit for assisting in the prediction of gastric cancer risk, wherein the test kit is used to detect a first ex vivo fecal sample of a subject before Helicobacter pylori eradication, and the first ex vivo fecal sample has not been diagnosed or identified as belonging to a low-risk group or a high-risk group for gastric cancer; a detection step is performed on the first ex vivo fecal sample to obtain a first detection result, wherein the detection step utilizes a first primer of the reagent as shown in SEQ ID NO: 1 and a second primer of the reagent as shown in SEQ ID NO: 2 for polymerase chain reaction, and the first detection result contains a plurality of 16S rRNA gene sequences, and the 16S rRNA gene sequences correspond to the abundance of a species of a first microbiota; and the abundance of the species of the first microbiota in the subject is compared with a cutoff value for the species, and it is determined whether the abundance of the species of the first microbiota meets the definition of a scoring system, wherein the definition of the scoring system includes: Megamonas monomorpha The first relative abundance of *Lactobacillus funiformis* YIT 11815 is greater than or equal to a first cutoff value; the second relative abundance of *Lacrimispora amygdalina* is greater than or equal to a second cutoff value; the third relative abundance of *Ruminococcus callidus* is greater than or equal to a third cutoff value; the fourth relative abundance of *Holdemanella porci* is greater than or equal to a fourth cutoff value; the fifth relative abundance of *Gluceribacter canis* is greater than or equal to a fifth cutoff value; the sixth relative abundance of *Blautia luti* is greater than or equal to a sixth cutoff value; the seventh relative abundance of *Acidaminococcus intestini* is less than a seventh cutoff value; and the eighth relative abundance of *Negativibacillus massiliensis* is less than an eighth cutoff value. The relative abundance of Amedibacillus dolichus was less than the 9th cutoff value;The tenth relative abundance of *Fumia xinanensis* is less than the tenth cutoff value, wherein the subject corresponding to the first ex vivo fecal sample is classified into the high-risk group for gastric cancer if at least five of the first bacterial phases meet the definition of the scoring system, and the first, second, third, fourth, fifth, sixth, seventh, eighth, ninth, and tenth cutoff values ​​are obtained by determining the species and abundance of the second bacterial phase in a normal individual, the species and abundance of the third bacterial phase in a high-risk individual for gastric cancer, and the species and abundance of the fourth bacterial phase in a low-risk individual for gastric cancer according to the maximum Youden index determined by the receiver operating characteristic curve, the normal individual does not have *Helicobacter pylori*, the high-risk individual for gastric cancer has *Helicobacter pylori* and meets the OLGA and OLGIM criteria for combined advanced stage, and the low-risk individual for gastric cancer has *Helicobacter pylori* and meets the OLGA criteria. Merging earlier standards with OLGIM.

2. The use of the reagent for detecting fecal microbiota as described in claim 1 in the preparation of a test kit for assisting in the prediction of the risk of gastric cancer, wherein the first cutoff value is 0.0006615945, the second cutoff value is 0.0016900495, the third cutoff value is 0.0000863035, the fourth cutoff value is 0.0002719795, the fifth cutoff value is 0.0005336830, the sixth cutoff value is 0.0000551330, the seventh cutoff value is 0.0003289255, the eighth cutoff value is 0.0002715880, the ninth cutoff value is 0.0001236705, and the tenth cutoff value is 0.0000875810.

3. The use of the reagent for detecting fecal microbiota as described in claim 1 or claim 2 in the preparation of a test kit for assisting in the prediction of the risk of gastric cancer, wherein when fewer than 5 of the first microbiota meet the definition of the scoring system, the subject corresponding to the first ex vivo fecal sample is classified as the low-risk group for gastric cancer.

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