E.coli Species Targeted

BLAST analysis of our STEC and general E.coli Primers

Scroll down to see the more general E.coli Primer hits. Some are categorized as STEC, EHEC, ETEC, EPEC, etc.. but not all NCBI names are guaranteed to include these generalized descriptors.

Of note- Petri Film technologies are known to fail to differentiate these species and novel selective culture is required as seen in Posse’ et al.

From Posse’

“Only a few food laboratories screen for these non-O157 STEC, mainly because of the absence of a specific International Organisation for Standardisation (ISO) method (ISO, 2001). Non-O157 STEC strains are a heterogeneous group that display a broad range of both genotypic and phenotypic differences (Schmidt et al., 1999; Bettelheim, 2000, 2003, 2007).

O157:H7 serotyped strains have a unique phenotypic feature, facilitating their isolation from food and faeces: they fail to ferment sorbitol within 24 h of incubation. Sorbitol MacConkey agar was developed to exploit this unique phenotypic feature (March & Ratnam, 1986). More recently, however, sorbitol-positive strains have been increasingly isolated from clinical cases (Gunzer et al., 1992; Bielaszewska et al., 1998; Karch & Bielaszewska, 2001), stressing the importance of screening food products for both sorbitol-positive and -negative O157.”

Labs using culture cannot tell you what species their plates are growing nor can they guarantee which of these thousands of strains their test will definitively pick up. For this reasons food outbreak testing is all done with DNA based testing in 2017.

For general E.coli primers, a validation should include at least one Strain from each of the “Big Six” non-O157 Shiga toxin producing E.coli strains as recommended by the CDC.

These are O26 (ATCC BAA-2196D-5), O45 (ATCC# BAA-2193D-5), O103 (ATCC# BAA-2215D-5) , O111 (ATCC# BAA2440D-5) , O121 (ATCC# BAA2219D-5) and O145 (ATCC# BAA2192D-5). All of these strains are detected with our general E.coli Primer sets.

We also confirmed ATCC 8739D-5, ATCC8739, and DH10B comp cells from NEB.

Sequence analysis from the PCR products hits these 500 other E.coli Strains. (BLAST search was limited to 500 hits).

BLAST analysis of the E.coli strains our general E.coli primers hit.