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From The Editor
Arguably, one of the biggest innovations in laboratory medicine over the last few decades has been the evolution of technologies away from batch-mode processing to random access formats. In pathology departments in the 1960s, immunoassays for detection for thyroid stimulating hormone (TSH) and other analytes were performed in batches, perhaps once per week, within specialized laboratories built for containment of the radioisotopes used to label antibodies. Rabbit antiserum, sometimes collected from local farm animals, was radioiodinated with Bolton-Hunter reagent to generate the key diagnostic ingredient. The test itself was most likely performed by a graying medical technologist, fortunately robed with protective gear, who was perpetually one year away from retirement. Many innovations in diagnostics over the past few decades have been fueled by the needs of specific patient populations and the need for rapid, medically actionable results. And fortunately, in clinical laboratories, as elsewhere in medicine, times have changed. Non-isotopic immunoassays were developed that could be automated, and more recently, random access immunoassay systems have been developed that eliminate batching requirements and improve turnaround time. In microbiology labs, blood culture systems now allow continuous monitoring for the presence of pathogen growth; these systems have largely replaced batch systems that require blind subculture. The fundamental impact of random-access, on-demand technologies is to provide results within a time frame that allows for maximum patient benefit. Earlier diagnoses often translate into earlier specific therapeutic interventions, which are more likely to result in favorable patient outcomes. Nucleic acid amplification techniques occupy an increasing important role in diagnosis and monitoring of infection, and I am fortunate to have been involved in this field since its inception. Though the pathogens themselves come from different phylogenetic domains, they all harbor genetic signatures encoded within their genomes that can be used to identify them, quantify infectious burden, determine virulence, and assess susceptibility or resistance to available drugs. The clumsy, contamination-prone techniques that I used in the 1980s have been largely replaced with real-time detection technology performed in closed systems, and DNA sequencing and microarray technologies developed under the auspices of the human genome project are making steady inroads into clinical laboratories. Diagnosticians have taken great leaps forward in their level of overall sophistication and familiarity with this technology. Phylogenetic analysis and identification of bacteria, fungi and viruses by direct DNA sequencing is quickly entering the mainstream, and will require us to add a few new words such as “bootstrapping” and “parsimonious” to our vocabulary. As promising and important as it is, however, molecular diagnostic testing in most labs is still akin to that of the radioimmunoassay laboratory of the 1960s. Despite the speed of the underlying detection technologies, the high technical skill requirements for reaction setup and for specimen processing impose practical limits on turnaround time. Specialized lab facilities are still required, and most testing is done in batches that are processed periodically, which limits turnaround time. But as molecular methods evolve, they will respond to the requirement for optimal clinical management. Cepheid’s GeneXpert® System does exactly that. Each cartridge is a self-contained, integrated PCR-facility in which all the steps of sample processing, target concentration and purification, reaction setup, amplification and detection are carried out. In-process controls are added to samples before target purification to monitor extraction and purification efficiency, and the precision and speed of fluid movements in the GeneXpert cartridge allow for a high degree of accuracy and reproducibility. As technologies like the GeneXpert become increasingly available, and as they evolve from batch-mode to on-demand formats, they will likely have an ever greater impact on patient treatment and management. As so-called real-time molecular diagnostics technology improves, so should the delivery of real-time patient results. In this first issue of the Cepheid ON-DEMAND, with the assistance of associate editor Ellen Jo Baron, we have highlighted one of the current uses of GeneXpert technology for MRSA surveillance. It is extremely gratifying to us at Cepheid that our technology could have such a dramatic impact, in such a short time, on patients’ lives and their well-being. That alone would be worth it, but witnessing the equally dramatic savings to hospitals make for a true win-win situation for hospitals and their patients.
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