Development Of Siderophore-Based Novel Diagnostic Systems For Bacterial Infections

Abstract

While the type of bacterial infection depends on many factors, such as the geographical region, personal hygiene and the efficiency of the personal immune system, such infections are very common throughout the world. Infections spread very rapidly mainly because bacteria have enough time to spread as the correct diagnosis takes a lot of time. Therefore, a point-of-care diagnostic system for bacterial infections would be very helpful in reducing the number of infected people as well as the cost to treat the infected patients. Bacteria possess chelating molecules called siderophores, in order to meet their iron needs. They secrete siderophores in large quantities and once those chelate iron, bacteria can absorb them again. The diagnostic systems introduced in this thesis target the secreted siderophores as well as their uptake. The method that focuses on siderophore secretion involves a novel technology that uses a lanthanide probe and an aptamer probe, which we call lanthanide-apta-switch. A proof-of-concept demonstration has been performed using a mercury-selective structure-switching aptamer which showed very promising results. We anticipate that this technology can be used to detect siderophores using a siderophore-selective structure-switching aptamer. The diagnostic method we developed, based on siderophore uptake, involves a probe that is an analogue of natural siderophores of bacteria which is then conjugated to a fluorescent dye. Preliminary results showed that our probe is taken-up by bacteria within 5 min. of incubation and the limit of detection is 105 CFU/mL. According to our results both diagnostic systems seem good candidates for point-of-care devices.