The Immunocard STAT! E. coli 0157 Plus is a rapid test for the detection of antigens from Shiga toxin-producing E. coli 0157 as an aid in the diagnosis of E. coli 0157:H7 infection. The test can be used to directly test stool specimens, or confirmatory stool cultures grown in MacConkey broth or on SMAC plates. The test is now currently performed routinely on all stool specimens submitted for culture, which yield growth on the SMAC plate.

Eschericia coli is a common microorganism found in normal human flora. While many different serotypes have been identified, certain strains have acquired genes for toxins from other bacterial species via bacteriophage plasmids. Shiga toxin producing E. coli 0157 usually carries one or more genes for Shiga toxin, placing it in a category of pathogens known as Shiga toxin-producing enterohemorrhagic E. coli (STEC). STEC strains of E. coli cause a wide spectrum of human diseases, including bloody and non-bloody diarrhea, hemorrhagic colitis, kidney failure, hemolytic uremic syndrome (HUS) and death. Morbidity and mortality rates in children, infants and the elderly are especially high. In addition, many states and institutions require a negative test prior to readmitting infected children to schools or day-care facilities. Outbreaks attributed to E. coli 0157 infection have most commonly been associated with undercooked beef and dairy products, but have also been traced to leaf lettuce, radish sprouts, alfalfa sprouts, unpasteurized cider and contaminated water.

To date, E. coli 0157:H7 has been the most commonly described STEC serotype. The CDC recommends that all patients with bloody stools submitted for routine stool culture be examined for the presence of E. coli 0157:H7. Some investigators recommend that all stools submitted for routine stool culture be examined for E. coli 0157:H7. Most sorbitol nonfermenting E. coli 0157 are motile and possess the H7 antigen. Occasionally, a sorbitol-nonfermenting strain of E. coli 0157 is either nonmotile, or motile with a nontypable flagellar antigen. Clinical laboratory evaluation of a strain need not include H7 antigen determination. Sorbitol-non-fermenting E. coli 0157 should be considered pathogenic, whether or not the H7 antigen is detected. Determination of H7 may be helpful epidemiologically, or for state and federal reporting purposes.

Immunocard STAT! E. coli 0157 Plus was designed for the rapid and accurate detection of Shiga toxin-producing E. coli O157. Accurate and rapid detection of Shiga toxin-producing E. coli O157 is necessary to prevent further spread of the organism, avoid unnecessary procedures such as surgery and to guide treatment decisions.

Test results should be used in conjunction with information available from the patient clinical evaluation and other diagnostic procedures.

A negative test result indicates the absence of Shiga toxin-producing E. coli 0157 antigens or that the levels of antigens are below that which can be detected by this test. Further testing should be performed with negative specimens to determine the cause of diarrhea. Optimal sensitivity is obtained by culture confirmatory methods.

Many states require a negative STEC or E. coli 0157 test result before a child can return to day care. For this purpose, to reduce the risk of sending infectious children back into these environments, a culture confirmatory method should be utilized.

Laboratories should comply with all local state and federal regulations for reporting STEC or E. coli 0157 disease.

Shiga-toxin producing E. coli 0157 causes both sporadic and epidemic outbreaks of disease. While the incidence of disease peaks in the summer months, cases occur year round. Due to the focal nature of the disease, incidence values range widely with geographic location, from zero to 3-4% in severe outbreaks. For this reason, predictive values for the ImmunoCard STAT! E. coli 0157 Plus test are subject to variation. The table below gives the expected predictive values based upon incidence.

The ImmunoCard STAT! E. coli 0157 Plus was evaluated at six locations. ImmunoCard STAT! E. coli 0157 Plus was tested on direct stool, 24 hour broth cultures and on sorbitol negative colonies from SMAC plates. In the table below,ImmunoCard STAT! E. coli 0157 Plus results are compared to latex testing of sorbitol negative colonies from a SMAC plate.