Development and standardization of immunochromatographic test for Shiga toxin-producing Escherichia coli (STEC) and enterotoxigenic Escherichia coli (ETEC) diagnosis.

Author(s)

Letícia Barboza Rocha

• Document type: Doctoral Thesis
• Press: São Paulo.
• Institution: Universidade de São Paulo (USP). Instituto de Ciências Biomédicas (ICB/SDI)
• Defense date: 2012-09-14

Examining board members

Roxane Maria Fontes Piazza; Elizabeth Natal de Gaspari; Beatriz Ernestina Cabilio Guth; Maria Leonor Sarno de Oliveira; Tania Mara Ibelli Vaz

• Advisor: Roxane Maria Fontes Piazza

Abstract

Shiga toxin-producing Escherichia coli (STEC) and enterotoxigenic Escherichia coli (ETEC) are worldwide involved in diarrheal diseases and produce the heat-labile (LT) and the Shiga (Stx1 and Stx2) toxins, which, cause injuries to man. The diagnosis is an important tool for the correct treatment and control of outbreaks. Thus, immunochromatographic assays (ICs) for ETEC and STEC based on toxins detection were developed and standardized using polyclonal antibodies-gold conjugated (PAbs) and their corresponding monoclonal antibodies (MAbs): anti-LT (IgG2b, 4.9 x 10-11 M), anti-Stx1 (IgG1, 2.5 x 10-10 M) and anti-Stx2 (IgG1, 6.1 x 10-10 M). The three ICs detect up to 15.6 ng/mL of LT, 15.6 ng/mL of Stx1 and 62.5 ng/mL of Stx2 and showed no cross-reaction with non-producers isolates of the respective target toxin. These results demonstrate the feasibility and applicability of the test ICs as diagnostic tools for diarrheagenic E. coli. (AU)