| This study described the 94 samples of nucleic acid molecules characteristic of Vibrio cholerae, which had been collected from Chongqing 1992-2006 epidemic and environmental testing. This study adopted the clustering analysis method of Polymerase chain reaction (PCR) technology, restriction endonuclease, pulsed-field gel electrophoresi(sPFGE) technology and BioNumerics V4.0 software UPGMA to analyze the specific target gene sequences of cholera enterotoxin A subunit gene (ctxA),toxin coregulated pilus A (tcpA), and total DNA.This study explored deeply the phylogenic relationship among the strains isolated during cholera outbreaks, the strains isolated from sea food samples and strains from outbreaks, to trace the source of cholera infection and changes of V. cholerae infection, and to investigate the characteristic of V. cholerae in local area, so as to support the policy- making on cholera control.Polymerase Chain Reaction(PCR)assay was employed to detect the 2 different kinds of pathogenicity-related genes. The results show that: In all the 94 strains under analysis,92 appeared to be ctxA toxigenic while 2 from sea fcod surveillance derived isolates were ctxA toxingene negative;91 appeared to be tcpA toxigenic while 2 from sea fcod surveillance derived isolates and 1 0139 strains isolated from patient were tcpA toxingene negative. PFGE was used for the molecular subtyping of V. cholerae, and its PFGE patterns were analyzed by BioNumerics version 4.0 software. 94 strains were clustered into 44 PFGE patterns when digested with Not I. Most PFGE patterns were divided into cluster A or cluster B or cluster C. The patterns of the Phange-Bio type Inada 1d strains isolated from patient in Chongqing in 2002 have same types. The patterns of the Inada Serotype strains obtained from Chongqing are 75% similar to the Ogawa Inada Serotype. The patterns of toxigeinc O139 strains isolated from turtles in the markets were identical with the patterns of strains appeared in the outbreaks respectively.We can get the conclusion that the closely related pandemic clone dusters of V. cholerae strains did exist in Chongqing, there are the phylogenic relationship among the strains isolated during cholera outbreaks in Chongqing in 2002, the characteristics of molecular typing of cholera O1 El Tor biotype strains isolates in Chongqing changed through the prevalence of Vibrio cholerae O1 El Tor biotype,strains from turtle are highly homology with epidemic strains, which points out turtle might be one of the major sources of outbreaks, sea food surveillance is one of important parts of cholera control strategy. PFGE of V.cholerae could be used for active surveillance and tracking for cholerae. |
