TUBEX® TF is a 10 minutes semi-quantitative in vitro diagnostic assay for detection of acute typhoid fever. It specifically detects the presence of IgM antibodies to the S. typhi O9 lipopolysaccharide antigen. This antigen is highly specific to S. typhi and other Salmonella serogroup D bacteria by its extremely rare sugar (a-D-tyvelose). IgM anti-O9 antibodies are normally not present in healthy individuals, and thus TUBEX® TF is highly specific. A positive TUBEX® TF result, together with typical clinical symptoms of typhoid fever, is highly suggestive of a typhoid infection.

TUBEX® TF is an inhibition binding assay. In short it detects the presence of anti-O9 IgM antibodies in patient serum by assessing the ability to inhibit a reaction between two colored and antigen/antibody-coated reagents. TUBEX® TF is a semi-quantitative assay, and thus the level of inhibition is proportional to the concentration of anti-O9 antibodies in the sample. The separation is performed in one step by magnetic force; where after the result is read visually and scored against a provided color scale.