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 Original Articles |
| Rapid Molecular Detection of Escherichia coli O157:H7 |
| Hyoung Shik Shin, M.D.*, Tae Geun Oh, M.D.*, Jong Sung Shin, M.D.*
Jung Hoon Ji, M.D.*, Bo Ra Son, M.D.† and Kyeong Seob Shin, M.D.† |
| Department of Internal Medicine* and Clinical Pathology†, College of Medicine,
Chungbuk National University, Cheongju, Korea |
Vol.33 Num.2 (p97~103)
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Background:Sorbitol fermenting Escherichia coli O157 were reported. And E. coli O157:H7 produce various Shiga toxin (Stx) such as Stx1, Stx2, or variants of Stx2. In this study, we tried to establish laboratory methods that detect E. coli O157:H7 quickly and precisely by analyzing sensitivity of colony hybridization test and PCR technique.
Methods:Stx1-producing E. coli ATCC 43890, Stx2-producing E. coli ATCC 43889, and Stx2vha- producing E. coli ATCC 51435 were tested. Three strains of E. coli were diluted with 0.1 g of diarrheal stools from 107 CFU to 101 CFU respectively. The stool samples were incubated overnight in MacConkey agar plates. A mean of 63 colonies were hybridized by stx1- and stx2-specific oligonucleotide probes. PCR for stx1 gene and stx2 gene was done after overnight- incubation of stool samples in the LB broth with vancomycin (6 ug/mL). Positive colonies by colony hybridization were confirmed by PCR for stx1 gene and stx2 gene.
Results:Colony hybridization test could detect Stx1-producing E. coli at 103 CFU per 0.1 g of stool, Stx2-producing E. coli at 105 CFU per 0.1 g of stool, and Stx2vha-producing E. coli at 104 CFU per 0.1 g of stool. PCR technique after enrichment in LB broth with vancomycin (6 ug/mL) could detect stx1-, stx2-, and stx2vha-containing E. coli at 10 CFU per 0.1 g of stool respectively.
Conclusion:A combination of colony hybridization and PCR after enrichment in broth with vancomycin (6 ug/mL) is useful for the rapid and precise diagnosis of infections of Shiga toxin-producing E. coli O157:H7. |
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Keywords : Escherichia coli O157:H7, Colony Hybridization, Polymerase Chain Reaction |
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