Key challenges and coping strategies for the detection of bacteria at ultralow concentrations

Bacterial contamination is often characterized by high infectivity, even at very low doses. Developing rapid, cheap, and simple methods to detect bacteria at ultralow-concentrations is essential for improving public health. Most of the published reviews are about particular detection principles, such as optical and electrochemical biosensors. To date, there are no reviews that discuss how to design materials for detecting bacteria at ultralow concentrations. First, the importance of detecting bacteria with ultralow concentrations is explained in the review. Additionally, research advances in PCR, electrochemistry, immunohistochemistry-based methods (ELISA and LFIA), colorimetric detection and surface-enhanced Raman scattering are discussed for ultralow-concentration bacterial detection. Finally, the challenges and future possibilities for detecting ultralow concentrations of bacteria are also presented.