A novel, time-effective approach for capturing bacteria from contaminated urine samples.

Domenico Vercellotti,Giuseppe Vercellotti,Paolo Domenichini,Vincenzo Ierardi

doi:10.31083/j.fbl2701022

Abstract

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. 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. 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. 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.

Highlights

A recent increase in antibiotic-resistant bacteria strains has driven researchers to develop new methods and devices that can correctly guide a physician to the most efficient antibiotic for a specific infection [1,2,3]
3.1 Assessment of bacterial concentration in urine samples The most remarkable result emerging from the optical images analysis, collected under 5× magnification, is a clearly visible, bright band that runs across the slide and parallel to the free surface of the urine samples (Fig. 3)
The band is made of bacteria captured from the urine contaminated samples, identifiable in the zoomed round areas obtained under a 40× optical objective lens

Summary

Introduction

A recent increase in antibiotic-resistant bacteria strains has driven researchers to develop new methods and devices that can correctly guide a physician to the most efficient antibiotic for a specific infection [1,2,3]. Many recent studies focused on different methods able to capture or separate bacteria from various environments, such as biological fluids, water, or food matrices [5,6] Indicative examples of these new approaches are the search and engineering of specific ligand that bind their targets with high affinity and specificity [7], magnetic beads [8], magnetic nanoparticles [9], microfluidic devices [10], immune-capturing techniques, and immune-magnetic separation [11]. Methods: 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 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. Conclusions: This approach is an easy, quick and economical method to concentrate living bacteria in a well-defined position onto a microscope slide, making them available for further diagnostic investigations

Objectives

Methods

Results

Discussion

Conclusion