Occurrence of diarrheagenic Escherichia coli genes in raw water of water treatment plants.
OBJECTIVE
The high incidences of waterborne diseases are frequently associated with diarrheagenic Escherichia coli (DEC). DEC may pose a health risk to people who contact surface water for recreation or domestic use. However, there is no published report on the monitoring of DEC in drinking water sources in Taiwan. In this study, the occurrence of DEC genes in raw water for water treatment plants in Taiwan was investigated.


METHODS
Raw water samples were taken from water treatment plants adjacent to the Kaoping River in southern Taiwan. Each water sample was treated with membrane filtration followed by DNA extraction from the concentrate and concentrate enrichment, respectively. The target genes for various DEC strains of genes were identified, including enteroaggregative E. coli (EAEC), enterohemorrhagic E. coli (EHEC), enteroinvasive E. coli (EIEC), enteropathogenic E. coli (EPEC), and enterotoxigenic E. coli (ETEC).


RESULTS
Among 55 water samples analyzed, DEC genes were detected in 16 (29.1%) samples. Strain-specific genes for EAEC, EHEC, EIEC, and EPEC were found in the percentages of 3.6%, 10.9%, 9.1%, and 9.1%, respectively. The specific gene for ETEC is not detected in the study. By looking at the presence/absence of specific genes and water sample characteristics, water temperature was found to differ significantly between samples with and without EHEC gene. In addition, pH levels differed significantly for EHEC and EPEC presence/absence genes, and turbidity was significantly different for water with and without EPEC genes.


CONCLUSIONS
DEC genes were detected in 29.1% of the raw water samples in the study location. The potential health threat may be increased if the treatment efficiencies are not properly maintained. Routine monitoring of DEC in drinking water sources should be considered.
Center for General Education, Cheng-Shiu University, Kaohsiung, Taiwan, Republic of China.
Shih-Wei
SW
Huang
Bing-Mu
BM
Hsu
Yen-Jui
YJ
Su
Dar-Der
DD
Ji
Wei-Chen
WC
Lin
Jyh-Larng
JL
Chen
Feng-Cheng
FC
Shih
Po-Min
PM
Kao
Yi-Chou
YC
Chiu
D002681:China; D004269:DNA, Bacterial / Q000235:genetics / Q000302:isolation & purification; D003967:Diarrhea / Q000382:microbiology*; D004586:Electrophoresis; D054308:Enteropathogenic Escherichia coli / Q000235:genetics* / Q000302:isolation & purification* / Q000378:metabolism; D004784:Environmental Monitoring / Q000379:methods; D015964:Gene Expression Regulation, Bacterial / Q000502:physiology*; D016133:Polymerase Chain Reaction; D045483:Rivers / Q000382:microbiology; D014865:Waste Disposal, Fluid / Q000379:methods*; D014871:Water Microbiology; D018508:Water Purification
D004269:DNA, Bacterial