Abstract:In order to investigate the pathogen causing an outbreak of diarrhea and test the reliability of 16S rDNA library in screening suspicious pathogen,the feces from 12 diarrheal patients in the period of outbreak were collected and all the bacterial genome in stool was extracted.Samples from three patients were randomly selected to analyze bacterial species based on 16S rDNA sequence analysis method established by State Key Laboratory for Infectious Disease Prevention and Control(China) and to screen for the pathogen causing diarrhea.Then,the specific gene of diarrheal pathogen screened by 16S rDNA library was further verified by PCR.This specific gene was also tested in samples from other 9 diarrheal patients.Eventually,the diarrheal pathogen which led to the outbreak of diarrhea this time was confirmed according to the detection rate of diarrheal pathogen in 12 stool samples.Results showed that Shigella or E.coli was tested to be positive in 2 out of 3 diarrheal patients by 16S rDNA sequence analysis.Shigella was proved to exist in stool of those two patients after the PCR test of Shigella specific virulence gene ipaH.Meanwhile,Shigella was also detected positively in 6 out of other 9 diarrheal patients with PCR.The total detection rate of Shigella was 66.7%(8/12).The result of 16S rDNA sequence analysis was consistent with that of PCR test because both results showed that the proportion of Shigella genome to bacteria genome in stool of patient Ⅲ was higher than that in stool of patient Ⅱ.Consequently,Shigella might be the primary pathogen causing the outbreak of diarrhea.In conclusion,the method of 16S rDNA library could find out the suspicious pathogen in a short time.Therefore,it is a novel method to conduct the screening for unknown disease pathogen in epidemics and outbreaks.