Submitted to: Journal of Microbiological Methods
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/21/2011
Publication Date: 7/30/2011
Citation: Lin, A., Nguyen, L., Lee, T., Clotilde, L.M., Kase, J.A., Son, I., Carter, J.M., Lauzon, C.R. 2011. Rapid O serogroup identification of the ten most clinically relevant STECs by Luminex microbead-based suspension array. Journal of Microbiological Methods. 87(1):105-110. doi:10.1016/j.mimet.2011.07.019. Interpretive Summary: E. coli O157:H7 bacteria have been linked to outbreaks of foodborne illness for over 20 years. Although E. coli disease is rare, it is sometimes very serious. The most serious cases are linked to production of a toxin by the bacteria: Shiga toxin. In addition to O157:H7 E. coli, other types of E. coli have been shown to produce Shiga toxin. In recent years some of these non-O157 Shiga toxin producing E. coli (non-O157 STEC) have also been linked to outbreaks of foodborne illness. There are many types of non-O157 STEC, and they are identified by differences in the molecules on their surface. In addition to O157, the most common dangerous STEC are O26, O45, O91, O103, O111, O113, O121, O128, and O145. These different O-type molecules are coded by differences in the bacteria’s genes. Unfortunately very few tools are available to food safety and health professionals for identification of non-O157 STEC. We have developed a test that detects the genes for the ten most common STEC O-types listed. Our test uses a high-tech system of magnetic fluorescent microbeads in which each O-type gene is detected by a different color fluorescent bead. There are ten different microbead colors – one for each O-type. The test uses thousands of beads of each color, which allows all ten tests to be performed simultaneously on a single small sample. In this paper we describe use of our new STEC test in other laboratories, where it correctly identified all ten STEC types, even in mixtures with non-E. coli bacteria.
Technical Abstract: Identification and serotyping of Shiga toxin-producing Escherichia coli during foodborne outbreaks can aid in matching clinical, food, and environmental isolates when trying to identify the sources of illness and ultimately food contamination. Herein we describe a Luminex microbead-based suspension array to identify the O serogroup of the ten most clinically relevant STECs: O26, O45, O91, O103, O111, O113, O121, O128, O145, and O157. The use of PCR followed by Luminex xMAP® technology enables the detection of multiple analytes in a single multiplex reaction with high throughput capabilities. One hundred and fourteen STEC isolates were correctly identified with no false positives among forty-six other organisms using this assay. Assay performance was tested in multiple laboratories using a panel of eleven different STEC serogroups on the Bio-Plex 200 and MAGPIX instruments. The STEC microbead-based suspension array can be performed in a 96-well plate format for high throughput screening in less than 4 hours. Furthermore, it is expandable, allowing for the addition of O serogroups should the need arise.