Diagnostics as essential tools for containing antibacterial resistance

Fast determination of antibiotics in whole blood

There is a need for analytical methods capable of monitoring blood antibiotic levels in real time. Here we present a method for quantifying antibiotic levels in whole blood that does not require any sample pretreatment. The tests employ the enzyme penicillinase to assay for penicillin G, penicillin V and ampicillin using a flow-injected biosensor, the Enzyme Thermistor. Optimal flow rates, sample volumes and pH were determined to be 0.5 mL/min, 100 μL and 7.0, respectively. Analysis of the antibiotics diluted in buffer gave a linear range of 0.17-5.0 mM. Calibration curves prepared using blood spiked with the antibiotics gave a linear range of 0.17-2.0 mM. Linear regression values for all of the calibration curves were 0.998 or higher. Assay cycle time was 5 min. The relative standard deviation value for 100 determinations of a mock blood sample spiked with penicillin G was 6.71%. Despite the elimination of sample pretreatment, no detectable clogging or signal drift was observed. The assay provides a fast, simple, reliable analytical method for determining antibiotic concentrations in blood without the need for any sample pretreatment. This is an important first step towards developing a device capable of real-time monitoring of antibiotic levels in whole blood. The technology has the potential to significantly improve the outcomes of patients undergoing critical care.

Integrated rapid-diagnostic-test reader platform on a cellphone

We demonstrate a cellphone-based rapid-diagnostic-test (RDT) reader platform that can work with various lateral flow immuno-chromatographic assays and similar tests to sense the presence of a target analyte in a sample. This compact and cost-effective digital RDT reader, weighing only ~65 g, mechanically attaches to the existing camera unit of a cellphone, where various types of RDTs can be inserted to be imaged in reflection or transmission modes under light-emitting diode (LED)-based illumination. Captured raw images of these tests are then digitally processed (within less than 0.2 s per image) through a smart application running on the cellphone for validation of the RDT, as well as for automated reading of its diagnostic result. The same smart application then transmits the resulting data, together with the RDT images and other related information (e.g., demographic data), to a central server, which presents the diagnostic results on a world map through geo-tagging. This dynamic spatio-temporal map of various RDT results can then be viewed and shared using internet browsers or through the same cellphone application. We tested this platform using malaria, tuberculosis (TB) and HIV RDTs by installing it on both Android-based smartphones and an iPhone. Providing real-time spatio-temporal statistics for the prevalence of various infectious diseases, this smart RDT reader platform running on cellphones might assist healthcare professionals and policymakers to track emerging epidemics worldwide and help epidemic preparedness.

Bench-to-bedside review: Rapid molecular diagnostics for bloodstream infection--a new frontier?

Among critically ill patients, the diagnosis of bloodstream infection poses a major challenge. Current standard bacterial identification based on blood culture platforms is intrinsically time-consuming and slow. The continuous evolvement of molecular techniques has the potential of providing a faster, more sensitive and direct identification of causative pathogens without prior need for cultivation. This may ultimately impact clinical decision-making and antimicrobial treatment. This review summarises the currently available technologies, their strengths and limitations and the obstacles that have to be overcome in order to develop a satisfactory bedside point-of-care diagnostic tool for detection of bloodstream infection.

Ready for a world without antibiotics? The Pensières Antibiotic Resistance Call to Action

Resistance to antibiotics has increased dramatically over the past few years and has now reached a level that places future patients in real danger. Microorganisms such as Escherichia coli and Klebsiella pneumoniae, which are commensals and pathogens for humans and animals, have become increasingly resistant to third-generation cephalosporins. Moreover, in certain countries, they are also resistant to carbapenems and therefore susceptible only to tigecycline and colistin. Resistance is primarily attributed to the production of beta-lactamase genes located on mobile genetic elements, which facilitate their transfer between different species. In some rare cases, Gram-negative rods are resistant to virtually all known antibiotics. The causes are numerous, but the role of the overuse of antibiotics in both humans and animals is essential, as well as the transmission of these bacteria in both the hospital and the community, notably via the food chain, contaminated hands, and between animals and humans. In addition, there are very few new antibiotics in the pipeline, particularly for Gram-negative bacilli. The situation is slightly better for Gram-positive cocci as some potent and novel antibiotics have been made available in recent years. A strong and coordinated international programme is urgently needed. To meet this challenge, 70 internationally recognized experts met for a two-day meeting in June 2011 in Annecy (France) and endorsed a global call to action ("The Pensières Antibiotic Resistance Call to Action"). Bundles of measures that must be implemented simultaneously and worldwide are presented in this document. In particular, antibiotics, which represent a treasure for humanity, must be protected and considered as a special class of drugs.

Molecular diagnostics: the changing culture of medical microbiology

Diagnostic molecular biology is arguably the fastest growing area in current laboratory-based medicine. Growth of the so called 'omics' technologies has, over the last decade, led to a gradual migration away from the 'one test, one pathogen' paradigm, toward multiplex approaches to infectious disease diagnosis, which have led to significant improvements in clinical diagnostics and ultimately improved patient care.

The crisis of no new antibiotics--what is the way forward?

Antibiotic use not only underpins modern medicine, but has brought huge changes to the world, especially in expectations of survival of children into adulthood. The theme of World Health Day, 2011, was "antimicrobial resistance: no action today and no cure tomorrow". The demise of antibacterial drug discovery brings the spectre of untreatable infections. To prevent this crisis immediate action is needed and a new initiative, Antibiotic Action, has been launched. By bringing together communities who need these drugs with academia, health-care professionals, and pharmaceutical companies, this initiative aims to strengthen and enhance academic-industrial partnerships, bring about revision of costly and laborious processes of licensing and regulation of new antibiotics, and address the economics of antimicrobial drugs (cost of use vs profit). A global alliance for antibiotic drug discovery and development would provide a platform for these initiatives.

The global need for effective antibiotics-moving towards concerted action

Antibiotic resistance has emerged as one of the greatest global health challenges to be addressed in the 21st Century. The risk of widespread antibiotic resistance threatens to mitigate the positive changes made in modernizing healthcare systems; therefore, fresh approaches are essential, as well as new and effective antibacterial drugs. In a globalized world, a spectrum of different interventions and health technologies must be employed to contain antibiotic resistance. Finding ways of accelerating the development of new drugs and diagnostic tools is one strategy, as is better surveillance of antibiotic resistance and ways of improving use of existing antibiotics. Moreover, a framework to regulate use is called for to avoid that potential new antibiotics are squandered. Finally, the ongoing pandemic spread of resistant bacteria illustrates that the problem can only be addressed through international cooperation and thus that any new strategy to manage antibiotic resistance must take into consideration issues of global access and affordability.

Conserving antibiotics for the future: new ways to use old and new drugs from a pharmacokinetic and pharmacodynamic perspective

There is a growing need to optimize the use of old and new antibiotics to treat serious as well as less serious infections. The topic of how to use pharmacokinetic and pharmacodynamic (PK/PD) knowledge to conserve antibiotics for the future was elaborated on in a workshop of the conference (The conference "The Global Need for Effective Antibiotics - moving towards concerted action", ReAct, Uppsala, Sweden, 2010). The optimization of dosing regimens is accomplished by choosing the dose and schedule that results in the antimicrobial exposure that will achieve the microbiological and clinical outcome desired while simultaneously suppressing emergence of resistance. PK/PD of antimicrobial agents describe how the therapeutic drug effect is dependent on the potency of a drug against a microorganism and the exposure (the concentration of antimicrobial available for effect over time). The description and modeling of these relationships quantitatively then allow for a rational approach to dose optimization and several strategies to that purpose are described. These strategies include not only the dosing regimen itself but also the duration of therapy, preventing collateral damage through inappropriate use and the application of PK/PD in drug development. Furthermore, PK/PD relationships of older antibiotics need to be urgently established. The need for global harmonization of breakpoints is also suggested and would add efficacy to antibiotic therapy. For each of the strategies, a number of priority actions are provided.