P2-48 Sensitive Detection of Escherichia coli O157:H7 Based on Cascade Signal Amplification in ELISA

Tuesday, August 2, 2016
America's Center - St. Louis
Shan Shan, Nanchang University, Nanchang, China
Daofeng Liu, Jiangxi Province Centers for Disease Control and Prevention, Nanchang, China
Qi Guo, Nanchang University, Nanchang, China
Songsong Wu, Nanchang University, Nanchang, China
Rui Chen, Nanchang University, Nanchang, China
Kai Luo, Nanchang University, Nanchang, China
Liming Hu, Nanchang University, Nanchang, China
Yonghua Xiong, Nanchang University, Nanchang, China
Weihua Lai, Nanchang University, Nanchang, China
Introduction: Foodborne pathogens are a major public health issue worldwide. Thus, a sensitive method for pathogen detection should be developed to achieve food quality and safety.

Purpose: In this study, cascade signal amplification in ELISA involving ds-ELISA and ic-ELISA was established to sensitively detect Escherichia coli O157:H7.

Methods: A complex was formed comprising anti-E. coli O157:H7 pAb, E. coli O157:H7, biotinylated anti-E. coli O157:H7 mAb, streptavidin, and biotinylated β-lactamase in ds-ELISA. Penicillin solution was then added into the ELISA well and hydrolyzed by β-lactamase. Afterward, the penicillin solution was transferred to ic-ELISA and sensitively detected.

Results: In the cascade signal amplification system, increasing the amount of added E. coli O157:H7 resulted in more β-lactamase and less penicillin. The detection sensitivity of E. coli O157:H7, which was 20 CFU/ml with the cascade signal amplification in ELISA, was 1,000 higher than that of traditional ELISA. Furthermore, the novel method can be used to detect E. coli O157:H7 in milk.

Significance: This new signaling strategy will facilitate analyses of highly sensitive foodborne pathogens.