[Distribution and molecular characteristics of Vibrio cholerae serogroups O1 and O139 isolates in estuary of Pearl River].
OBJECTIVE
Through systematic monitoring of the number and strain types of O1 and O139 Vibrio cholerae in the Pearl River estuary waters to analyze it's relevance with the temperature of environment, and the relevance between strains in water and isolates during outbreaks and epidemics as well as to estimate the methods used for environmental water detection and the potential role in cholera surveillance program.


METHODS
Twenty-four stations along the Pearl River were selected and the water samples were collected monthly from March 2006 to February 2007. V. cholerae O1 and O139 strains were isolated from the samples. Real-time PCR established in our laboratory was used to detect V. cholerae O1 and O139. Air temperature and water temperature were collected during sampling. Pulsed field gel electrophoresis (PFGE) was applied in molecular typing of the isolates.


RESULTS
862 water samples were collected during the study period. A total number of 77 O1 and O139 V. cholerae were isolated in 67 water samples and the positive rates were 7.77% for isolation and 26.33% for real-time PCR. Seasonal trend of positive rates by month were approximately coincident with the change of water temperature. The positive rates in the stations in urban area were higher than those in other areas. Toxigenic O139 strains were found in one station located in downstream of a marine market. Most of the O1 and O139 isolates were non-toxigenic. No trend of seasonal variation of the strains was noticed. Within these 75 isolates, 49 PFGE patterns were identified and the patterns differed widely with the similarity of 57.4% - 100%.


CONCLUSIONS
V. cholerae existed as the natural habitat in estuary water of the Pearl River and showed obvious genetic diversity. Data from monitoring waters might show the separation of strains with certain seasonal association. But the crowd did not show the relationship between the infections. Results from water surveillance program might provide indicators on the appearance of cholera pathogen which might be used in assessing the environmental risk of cholera epidemics as well as the alert of cholera.
Wang
Duo-Chun
DC
State Key Laboratory for Infectious Disease Prevention and Control, National Institute of Communicable Disease Control and Prevention, Chinese Center of Disease Control and Prevention, Beijing 102206, China.
Wang
Xiao-Mei
XM
Zhong
Hao-Jie
HJ
Zhang
Jing
J
Tan
Hai-Ling
HL
Chen
Jing-Diao
JD
Li
Bai-Sheng
BS
Zheng
Hui-Zhen
HZ
Cui
Zhi-Gang
ZG
Ke
Chang-Wen
CW
Deng
Xiao-Ling
XL
Gao
Yong-Jun
YJ
Wang
Zi-Jun
ZJ
Kan
Biao
B
D016521:Electrophoresis, Gel, Pulsed-Field; D004784:Environmental Monitoring; D010802:Phylogeny; D016133:Polymerase Chain Reaction; D012621:Seasons; D013696:Temperature; D041241:Vibrio cholerae O1 / Q000145:classification / Q000235:genetics* / Q000302:isolation & purification*; D041242:Vibrio cholerae O139 / Q000145:classification / Q000235:genetics* / Q000302:isolation & purification*