Imaging Bacteria with Radiolabelled Probes: Is It Feasible?

Alberto Signore,Guillermina Ferro-Flores,Søren Hess,Vera Artiko,Sanjay K Jain,Martina Conserva,Mike Sathekge,Mick M Welling

doi:10.3390/jcm9082372

Abstract

Bacterial infections are the main cause of patient morbidity and mortality worldwide. Diagnosis can be difficult and delayed as well as the identification of the etiological pathogen, necessary for a tailored antibiotic therapy. Several non-invasive diagnostic procedures are available, all with pros and cons. Molecular nuclear medicine has highly contributed in this field by proposing several different radiopharmaceuticals (antimicrobial peptides, leukocytes, cytokines, antibiotics, sugars, etc.) but none proved to be highly specific for bacteria, although many agents in development look promising. Indeed, factors including the number and strain of bacteria, the infection site, and the host condition, may affect the specificity of the tested radiopharmaceuticals. At the Third European Congress on Infection/Inflammation Imaging, a round table discussion was dedicated to debate the pros and cons of different radiopharmaceuticals for imaging bacteria with the final goal to find a consensus on the most relevant research steps that should be fulfilled when testing a new probe, based on experience and cumulative published evidence.

Highlights

The diagnosis of bacterial infections remains a serious medical challenge, as they are among the main causes of mortality and morbidity worldwide
Since antimicrobial compounds act on processes that are unique to bacteria, it has been proposed that radiolabelled antibiotics should be able to distinguish microbial from non-microbial inflammation, because of their specific binding to the causative agents
The focus of its application is shifting from mere diagnosis of infection to prognostication, to predict the response to treatment, to identify resistant strains and to identify and target at-risk patients for prevention

Summary

Introduction

The diagnosis of bacterial infections remains a serious medical challenge, as they are among the main causes of mortality and morbidity worldwide. Since antimicrobial compounds act on processes that are unique to bacteria, it has been proposed that radiolabelled antibiotics should be able to distinguish microbial from non-microbial inflammation, because of their specific binding to the causative agents. Another important problem of antibiotics is the risk of a resistance mechanism in bacteria that are increasingly common and could prevent the specific binding of the antibiotic ligand, leading to poor uptake. Since antibiotics are designed to kill or disable the bacteria with high potency, many radiolabelled antibiotics do not accumulate in the bacteria, and may not provide a high enough contrast from the surrounding mammalian cells [2] For these reasons the gold standard for bacterial infection imaging has not yet been found. This remains an open goal, difficult to achieve, at the same time, crucial for the management, treatment and follow-up of patients with suspected bacterial infections

Imaging Bacteria in Humans

Conclusions