Thermo Scientific™ Wellcolex™ E. coli O157

Description

Rapidly identify Escherichia coli O157 isolates on laboratory media using Thermo Scientific™ Remel™ Wellcolex™ E. coli O157 latex agglutination test. The inability of most E. coli O157:H7 to ferment sorbitol has been used to differentiate them in the laboratory. MacConkey agar containing sorbitol instead of lactose (SMAC) is often used as a primary screening medium^1,2. Testing suspect colonies with Wellcolex* E. coli O157 determines whether the isolate belongs to the O157 serogroup.

Verocytotoxin-producing E. coli O157 are an important cause of diarrhoea, haemorrhagic colitis and haemolytic uraemic syndrome^3,4. The pathogenicity of this organism is due to the expression of verocytotoxin (VT1 and/or VT2)^5-7. Enteritis due to other serotypes is not unusual but in contrast to the majority of isolates, most E. coli O157:H7 do not ferment sorbitol and this has been used as a differential feature for laboratory identification. Testing suspect colonies with Wellcolex* E. coli O157 helps determine whether the isolate belongs to the O157 serogroup.

The Wellcolex* E. coli O157 Rapid Latex Test is categorised as highly complex under the Clinical Laboratory Improvement Act (CLIA88 : Test System Code 40262; Analyte Code 1604).

• Ready-to-use: Color coded latex and control reagents
• Rapid: Results within 30 seconds.
• Easy-to-interpret: Visible agglutination
• Less sample required

The Wellcolex* E. coli O157 Test Reagent consists of a buffered suspension of red polystyrene latex particles coated with rabbit IgG antibodies specific for E. coli O157 and 0.05% Bronidox^® as preservative. When a drop of the reagent is mixed on a card with a suspension of E. coli O157 organisms, rapid agglutination occurs through the interaction of specific IgG and O157 lipopolysaccharide antigen.

Some faecal coliforms can cause non-specific aggregation of latex particles, particularly when grown on sugar containing media such as MacConkey. Therefore a control latex is provided to assist with the identification of non-specific reactions. The control latex consists of a buffered suspension of red polystyrene latex particles coated with non-immune rabbit IgG and 0.05% Bronidox^® as preservative.

The kit is also supplied with Positive and Negative controls. The positive control contains a dilute suspension of heat killed E. coli O157 antigens and 0.05% Bronidox^® preservative. The negative control contains a dilute suspension of heat killed E. coli O106 antigens and 0.05% Bronidox^® preservative.

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Remel™ and Oxoid™ products are now part of the Thermo Scientific brand.