Escherichia coli (E.coli) O157:H7 Quantified Bacterial DNA Standards

Overview

E. coli O157:H7 is a rod-shaped, gram negative bacterium. It is an enterohemorrhagic strain of the common E. coli bacterium and infection by the O157:H7 strain is commonly associated with hemorrhagic colitis. E. coli O157:H7 is recognized by its somatic (cell wall) antigen (O157) and its flagella antigen (H7). In addition, E. coli O157:H7 is known to produce Shiga-like toxins, which cause severe symptoms. While most patients can recover from the infection, up to 15% of the patients may develop hemolytic uremic syndrome, a type of kidney failure that could be fatal. Infection of E. coli O157:H7 usually results from consumption of poorly prepared food including undercooked meat (particularly ground beef), untreated water or raw unpasteurized milk.

Norgen’s E. coli O157:H7 Quantified Bacterial DNA Standards are cloned fragments of the two Shiga-like toxin regions purified using Norgen’s sample preparation technology. They include partial sequences of STX-1 subunit A gene and STX-2 subunit A gene. Please refer to Appendix A for sequence information. The purified DNA is quantified vigorously using multiple methods including spectrophotometry, gel densitometry and real-time PCR. It is intended to be used as positive controls or PCR quantification standards for E. coli O157:H7. This product is compatible with Norgen Biotek's E. coli O157:H7 Taqman PCR Detection Kit (Cat. TM41350) and E. coli O157:H7 Taqman PCR Detection Probe/Primer and Control Set (Cat. TM41310).

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Supporting Data

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Figure 1. E coli O157:H7 DNA Standard. 2 μL& of Norgen's E coli O157:H7 Quantified Bacterial DNA Standard and serial dilutions (colored curves) were used in a 20 μL E coli O157:H7 -specific PCR reaction using Norgen's 2X PCR Master Mix (#28007). Utilizing Norgens' STX-1 and STX-2 specific TaqMan Primers/Probes a set of reactions was set up for detecting the STX1 (Shiga-like toxin) gene and another for detecting the STX2 gene. The real-time PCR reactions were 10 μL master mix, 2 μL Primer/Probe mix, 2 μL of Quantified Bacterial DNA Standard, and 6 μL of nuclease free water, and were performed on a Bio-Rad CFX Real-Time PCR System. No template controls with water were also performed (Black curves). Norgen's E coli O157:H7 Quantified Bacterial DNA showed consistent amplification down to 20 copies/μL.

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