A better method for confirming Helicobacter pylori infection in Mongolian gerbils.
BACKGROUND
Our aim was to evaluate the accuracy of the stool antigen test and the optimal time point for detecting Helicobacter pylori infection in a Mongolian gerbil model.


METHODS
We inoculated 8-week-old Mongolian gerbils with H. pylori (Vac A (+)/CagA(+)). The gerbil-infected model was developed as follows: H. pylori was put into broth (about 10(9) CFU/ml), and 50 gerbils were then fed with 1 ml intragastrically twice within a 3-day interval. Another ten gerbils were fed broth only. Twenty-six weeks after the inoculation, the gerbils were killed. The gastric mucosa was sampled for a series of examinations including culture, histology, rapid urease test, and polymerase chain reaction. Stool samples for a stool antigen test, H. pylori-specific stool antigen assay (HpSA), were collected during weeks 4, 6, 8, 12, and 26 after inoculation. Of the 50 gerbils inoculated with H. pylori, the inoculation was successful in 88%. Severe active gastritis, ulceration, and intestinal metaplasia were obvious.


RESULTS
The HpSA test results were sensitivity, 88.6%; specificity, 100%; positive predictive value (PPV), 100%; negative predictive value (NPV), 54.5%, and accuracy, 90%. The HpSA test began to be more sensitive and accurate (P < 0.05) beginning during week 6 after inoculation. We also found that H. pylori could be detected earlier and more easily in the group with high H. pylori density.


CONCLUSIONS
HpSA seems to be suitable for confirming colonization of gerbils with H. pylori. The optimal testing time point is around 6 weeks after inoculation. This test is a good choice for long-term observation of H. pylori infection in Mongolian gerbils.
Kuo
Chao-Hung
CH
Division of Internal Medicine, Kaohsiung Municipal Hsiao-Kang Hospital, Kaohsiung, Taiwan.
Hu
Huang-Ming
HM
Tsai
Pei-Yun
PY
Yang
Sheau-Fang
SF
Chang
Lin-Li
LL
Wang
Jaw-Yuan
JY
Chen
Angela
A
Jan
Chang-Ming
CM
Wang
Wen-Ming
WM
Wu
Deng-Chyang
DC
D000818:Animals; D000942:Antigens, Bacterial / Q000032:analysis*; D001706:Biopsy; D004269:DNA, Bacterial / Q000235:genetics*; D003937:Diagnosis, Differential; D004195:Disease Models, Animal; D005243:Feces / Q000382:microbiology; D005753:Gastric Mucosa / Q000382:microbiology* / Q000473:pathology; D005756:Gastritis / Q000175:diagnosis / Q000382:microbiology*; D005849:Gerbillinae; D016481:Helicobacter Infections / Q000175:diagnosis* / Q000382:microbiology; D016480:Helicobacter pylori / Q000235:genetics / Q000276:immunology / Q000302:isolation & purification*; D016133:Polymerase Chain Reaction; D011237:Predictive Value of Tests; D051381:Rats; D012720:Severity of Illness Index
D000942:Antigens, Bacterial; D004269:DNA, Bacterial