E. Coli O157 Antigen Rapid Test

Description

Intended Use

E. coli O157 Antigen Rapid Test is an in vitro immunoassay for the direct and qualitative detection of antigens from shiga-toxigenic E. coli O157.

E. coli O157 Antigen Rapid Test is intended to aid in the rapid diagnosis of E. coli O157 infection. Human fecal specimens can be used directly by the test. Negative results do not preclude E. coli O157 infection and should be confirmed via culture or molecular method.

Introduction

Escherichia coli is a gram-negative, facultatively anaerobic bacterium of the genus Escherichia commonly found in the lower intestine of endotherms as normal gut flora1.While many different serotypes have been identified, certain strains of E. coli have acquired genes for toxins from other bacterial species via bacteriophage plasmids. Shiga-toxigenic groups of E. coli (STEC) are food-borne pathogens that cause gastrointestinal illness, hemorrhagic colitis, hemolytic uremic syndrome (HUS) and death, although infection can be asymptomatic. Morbidity and mortality rates in children, infants and the elderly are especially high2.

E. coli O157: H7 is one of the STEC serotypes most often implicated in outbreaks3.The pathogens can spread by fecal-oral route, and have also been traced to contaminated raw leaf green vegetables, water and undercooked meat. Transmission is via the fecal-oral route, and most illness has been through distribution of contaminated raw green vegetables and undercooked meat4. Most sorbitol-nonfermenting E. coli O157 are motile and possess the H7 antigen. However motility can be difficult to elicit, resulting in failure to detect the H7 antigen. Besides, a sorbitol-nonfermenting strain of E. coli O157 is occasionally either nonmotile or motile with a nontypable flagellar antigen (O157: H-). Therefore, H7 antigen determination is not necessary for clinical laboratory evaluation of a strain of E. coli O157: H75.

Diagnostic methods for E. coli O157 include culture on Sorbitol-MacConkey (SMAC) agar followed by confirmatory testing6. However, culture diagnosis is time-consuming. Swifter diagnosis is possible using quick E. coli DNA extraction plus PCR techniques which is often an expensive method and requires well-trained personnel and sophisticated equipment7. Latex agglutination test is also feasible, and antibody detection is also feasible under development. Meanwhile, owing to the simplicity and rapidity, enzyme immunoassay (EIA) and immnunochromatography for either O157 antigens or toxins could be valuable during outbreak investigations. The E. coli O157Antigen Rapid Test Device is a qualitative, lateral flow immunoassay for the detection of shiga-toxigenic E. coli O157 in human fecal specimens. The test is specific to shiga-toxigenic E. coli O157 antigens with no known cross-reactivity to normal flora or other intestinal pathogens.