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J Microbiol Methods. 2008 Oct;75(2):329-34. doi: 10.1016/j.mimet.2008.07.010. Epub 2008 Jul 20.

Characterization of Escherichia coli O3 and O21 O antigen gene clusters and development of serogroup-specific PCR assays.

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TEDA School of Biological Sciences and Biotechnology, Nankai University, 23 Hongda Street, TEDA, Tianjin 300457, China.


Escherichia coli O3 and O21 are associated with enteroaggregative E. coli (EAEC). EAEC strains are often non-typable using the routine agglutination method due to their aggregative phenotype. Typing of E. coli O3 and O21 may also be impeded by cross-reactions with O152 or O83. In this study, the O antigen gene clusters of E. coli O3 and O21 were characterized, and PCR assays based on O antigen specific genes wzx (encoding O unit flippase) and wzy (encoding O unit polymerase) from each strain were developed. By screening against all 186 known E. coli O serotypes, the PCR assays were shown to be highly specific to O3 and O21 respectively. The sensitivity of the assays was determined to be 1 pg per microl of chromosomal DNA and 2 CFU per 10 g of water samples. The PCR assays were also applied to 658 clinical E. coli isolates, and 100% of detection accuracy was obtained. The PCR assays developed here are suitable for the detection and identification of E. coli O3 and O21 strains in environmental and clinical samples.

[Indexed for MEDLINE]

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