Ultrasensitive monoclonal antibody-based Salmonella detection through fluorescence single bacterial cell imaging selectively enhanced by tyramide signal amplification

Salmonella is one of the most common foodborne pathogens. In this work, we developed an ultrasensitive imaging method for the detection of Salmonella by using broad-spectrum anti-Salmonella monoclonal antibody and the tyramide signal amplification technique. The monoclonal antibody used was designed in such a way that it exhibited high affinity for a wide range of Salmonella serotypes, including Typhimurium, Enteritidis and others. Through subsequent tyramide signal amplification, we successfully visualized bright fluorescent images of single bacterial cells through fluorescence microscopy. The detection limit of the method is as low as 100 CFU/mL for S. Typhimurium in both pure culture and artificially contaminated chicken rinsates, and no cross-reactivity with control bacterial strains was observed. We demonstrated that this method provided sensitive and broad-spectrum detection of 13 serotypes of common Salmonella, both in purified bacterial samples and in real chicken meat samples. This method does not require time-consuming amplification or culture steps and can be completed within 4 h, making it sensitive enough to detect pathogenic bacteria directly. This technique can be applied for clinical testing, food safety assessment, and environmental monitoring of Salmonella contamination.