Evaluation of Immunochromatography-based Rapid Detection Kit for Fecal Escherichia coliO157

Abstract

"Quix" is an immunochromatography-based direct detection kit for the E. coli O157 LPS antigen in the patient's stool. The present study was conducted to evaluate the efficacy of the kit for rapid diagnosis of enterohemorrhagic Escherichia coli (EHEC) O157 infection. Sensitivity of the kit was determined using a pure culture of a clinical isolate of E. coli O157. Analytical sensitivity was found to be 5 x 10(5) CFU/ml. When compared with the culture method using fecal samples of 64 patients and with bloody diarrhea, sensitivity and specificity were 95.0% (19/20) and 86.4% (38/44), respectively, and overall agreement to culture method was 89.1% (57/64). One patient was found positive by culture method while negative in the present method, where the sample contained a low number of the cells less than the detection limit. Four of the six patients with a negative result by culture method and positive in the present method, were confirmed E. coli O157 infection by positive IgM antibody response against the E. coli O157 LPS. The discrepancy between the two methods seemed to be attributable to antibiotic administration. In one patient, Salmonella urbana (O30(1)30(2)) was detected. The O30(1) antigen of this bacterium is well known to be identical to the E. coli O157 antigen. When the present method was compared with an ELISA-based E. coli O157 LPS antigen detection kit, sensitivity and specificity were 100% (11/11) and 82.1% (23/28), and overall agreement to ELISA method was 87.2% (34/39). From these findings, Quix is useful as a rapid diagnostic kit in the primary clinics, outpatient or bedside use. E. coli O157 LPS antigen in patient's fecal samples can be detected in about five minutes with this simple procedure. Early diagnosis using such a simple kit will largely contribute for the early treatment and prevention of severe complications of the E. coli O157 infection.

EVALUATION OF COLONOSCOPIC FINDINGS IN PATIENTS WITH DIARRHEAGENIC ESCHERICHIA COLI‐INDUCED HEMORRHAGIC COLITIS

“…Although some commercial rapid laboratory tests 19 for detecting the lipopolysaccharide (LPS) antigen of O157 or Stx are widely available in most hospital laboratories, they can pose problems in that they do not always produce a 'rapid' result for physicians. That is, in tests detecting the LPS antigen of O157, low bacterial quantity in the stool specimen can result in a false negative, 20 or a cross-reaction to Salmonella or Citrobacter can lead to false positive results. 19,20 Tests for detecting Stx usually require that a bacterial colony forms on the culture medium, 21,22 thus taking more time to make a diagnosis of EHEC infection.…”

“…That is, in tests detecting the LPS antigen of O157, low bacterial quantity in the stool specimen can result in a false negative, 20 or a cross-reaction to Salmonella or Citrobacter can lead to false positive results. 19,20 Tests for detecting Stx usually require that a bacterial colony forms on the culture medium, 21,22 thus taking more time to make a diagnosis of EHEC infection. Some attempts have been made to apply these tests directly to the detection of Stx in a patient's stool infected by EHEC, but it has been pointed out that the tests' sensitivity for detecting Stx is usually low or ambiguous.…”

Novel Strategies To Enhance Lateral Flow Immunoassay Sensitivity for Detecting Foodborne Pathogens

“…Antibodies bind to the surfaces of these gold particles with enormous strength when correctly coupled, thus providing a high degree of long-term stability. , Hence, ligands exhibit good compatibility with biomolecules and can retain biochemical activities of tagged biomolecules. Colloidal gold-based LFI has been applied to detect foodborne pathogens. − Furthermore, a LFI device has been used to determine the analytical sensitivity of E. coli O157 of approximately 10 5 CFU/mL. , Preechakasedkit et al also used colloidal gold-based LFI strip to detect S. typhimurium , and the limit of detection was 1.14 × 10 5 CFU/mL. Ueda et al applied the colloidal gold LFI strip to detect L. monocytogenes , and the detection limit of this assay was 10 6 CFU/mL.…”

“…43−50 Furthermore, a LFI device has been used to determine the analytical sensitivity of E. coli O157 of approximately 10 5 CFU/mL. 51,52 Preechakasedkit et al 53 also used colloidal gold-based LFI strip to detect S. typhimurium, and the limit of detection was 1.14 × 10 5 CFU/mL. Ueda et al 54 applied the colloidal gold LFI strip to detect L. monocytogenes, and the detection limit of this assay was 10 6 CFU/mL.…”

Evaluation of an Immunochromatography Strip Assay for the Detection of Salmonella Sp. from Poultry

“…Similar test kits for detection of different bacterial and viral pathogens have been developed. 10,12 The objective of the study was to evaluate a commercial immunochromatography-based strip assay as a rapid detection tool for the preharvest control of Salmonella in poultry. The immunochromatographic assay a relies upon colloidal gold-labeled anti-Salmonella sp.…”