Establishment Of Urea Breath Test Method For Detection H. Pylori In Mice And Analysis The Influence Factor

Objectives:To develop and evaluate the13C-urea breath test and14C-urea breath test（13C-UBT and14C-UBT）method for following the course of H. pylori infection inmice model, to explore the conditions and methods of the urea breath test in mice,analysis the influencing factor such as breath apparatus,conditions and biologicalfactor in the H. pylori-mice model.The research could offer a non-invasive andreal-time method for detection the H. pylori in mice. It can provide an objectiveevaluation of the immunoprotection effect of the H. pylori accine in mice.Also thisoffers a simple,quick,cheap and reliable diagnosis method to discuss pathogenicity ofH. pylori.Methods：BABL/c mice of six to eight weeks were gavaged with the different13C-Urea、14C-Urea dosage and detected within the different time to establish the13C-UBT、14C-UBT-mice model;the mice were challenged with the different levels of H.pyloricontent and detected within the same time to discuss the relationship between thecontent and time in13C-UBT; the mice were gavaged with the different levels ofH.pylori content and detection time to search the relevance between them in13C-UBTand14C-UBT.We explored the influencing factor of the H.pylori urea breath test in mice, anddetermined the tissue which the influencing bacterium located at; isolated culture andscreened the urease positive bacterium which influences the urea breath test in mice;determined the screened bacterium by ueing the mass spectrum and16srDNA-PCR sequencing,then qualitated and quantitated their urease enzymic activity.Results：The urea dosage and the same breath time had the direct correlation in both of13C-UBT and14C-UBT in mice; the number got higher following the detection timewhen mice were gavaged with the same dosage until it reachs the maximum,thendecreasing.We established13C-UBT and14C-UBT method for following the course of H.pylori infection in mice model successfully: using0.1mg-13C-Urea,300ml activityspace for mice, breathing10min after gavaged with urea, collect250ml gases fordetection; using0.556KBq-14C-Urea,200ml activity space for mice, breathing10minafter gavaged with urea, collect150ml gases for detection; the number got higherfollowing the mice gavaged the higher levels of H.pylori content in both13C-UBT and14C-UBT when breathing the same time after urea;13C-UBT and14C-UBT had thesimilar curve while the mice were gavaged the different levels of H.pylori content,and the low level had the strong influence.1×109CFU of H.pylori content had the bestcurve tendency.We successfully determined stomach and small intestine which the influencingbacterium located at, screened155urease positive bacterium; by using the massspectrum and16srDNA-PCR sequencing, lots of them were Escherichia coli.Pasteurella pneumotropica,Staphylococcus lentus,Haemophilus influenzae andStreptococcus thoraltensis had also been detected. The urease enzymic activity ofH.pylori was remarkably higher than others.Conclusions：(1)We successfully established13C-UBT and14C-UBT method for following thecourse of H. pylori infection in mice model;(2)The detected number was related to the gavaged urea dosage, H.pylori content andbreath time in13C-UBT and14C-UBT.The low level of H.pylori content had been thestrong influence and H.pylori content getting1×109CFU had been faintly influenced. (3)Although the urease enzymic activity of the screened bacterium was remarkablylower than H. pylori, we should pay more attention to their affection in the urea breathtest.