Background: A fundamental step in the race to design a rapid diagnostic test for antimicrobial resistance is the separation of bacteria from their matrix. Many recent studies have been focused on the development of systems capable of separating and capturing bacteria from liquid environments. Methods: Herein, we introduce a new approach to this issue by using the natural bacteria tendency to accumulate at naturally-occurring interfaces, such as liquid-gas and liquid-solid interfaces, where also organic molecules like lipids, proteins, and polysaccharides accumulate. This bacterial behavior leads to the formation of a superficial layer close to the interface rich in bacteria, from which it is possible to capture a consistent amount of bacteria by means of surfaces with high chemical affinity to the outer bacteria surface. Results: This paper demonstrates how to capture bacteria from contaminated urine samples, by means of commercial microscope slides coated with positively charged biomolecules, without the utilization of the bacterial culture step for multiplying the bacteria. Conclusions: This approach is an easy, quick and economical method to concentrate living bacteria in a well-defined position onto a microscope slide, thus making them easily available for further diagnostic investigations.