Role of Molecular Diagnostics in the Management of Infectious Disease Emergencies

Abstract

In the setting of infectious disease emergencies, rapid and accurate identification of the causative agent is critical to optimizing antimicrobial therapy in a timely manner. It is clearly evident that the age of molecular diagnostics is now upon us, with real-time PCR becoming the standard of diagnosis for many infectious disease emergencies in either monoplex or multiplex format. Other molecular techniques such as whole or partial genome sequencing, microarrays, broad-range PCR, restriction fragment length polymorphisms, and molecular typing are also being used. However, for most small clinical laboratories, implementation of these advanced molecular techniques is not feasible owing to the high cost of instrumentation and reagents. If these tests are not available in-house, samples can be sent to national reference laboratories (eg, Mayo Medical Laboratories and Quest Diagnostics) for real-time PCR assays that can be completed in 1 day. It is anticipated that over time commercial real-time PCR tests and instrumentation will become more standardized and affordable, allowing individual laboratories to conduct tests locally, thus further reducing turnaround time. Although real-time PCR has been proved to expand our diagnostic capability, it must be stressed that such molecular methodology constitutes only an additional tool in the diagnosis of infectious diseases in emergency situations. Phenotypic methodologies (staining, cultures, biochemical tests, and serology) still play a critical role in identifying, confirming, and providing antibiotic susceptibility testing for many microbial pathogens. As multiplex assays become increasingly available, there will be even greater temptation for taking a “shotgun” approach to diagnostic testing. These new technologies will not substitute for a proper history and physical examination leading to a thoughtful differential diagnosis. None the less, these new molecular tests increase the capability of the diagnostician to rapidly identify the microbiological etiology of an infection. An added advantage of rapid diagnostic tests often not emphasized is the capability to rule out certain diagnoses for which unnecessary antimicrobial therapy may otherwise be instituted and/or continued.

The combined-disk boronic acid test as an accurate strategy for the detection of KPC carbapenemase in Central America

“…The diagnostic accuracy of these tests varies and these tests are sometimes used as confirmatory tests. However, molecular tests have remained the gold standard for the identification and characterization of the resistance mechanism [6,13].…”

Future of diagnostic microbiology

“…The FDA has now approved NAATs for multiple viruses and bacteria; some are listed in Table 6. [23] The presence of these organisms usually indicates diseases because they are not normally found on human body surfaces or tissues. Many bacteria encountered commonly in clinical practice such as Staphylococci and Escherichia coli are frequently a part of the commensal flora.…”

Diagnostic Microbiology: Present Status and Future Prospect

“…The technology is now being used with blood culture and for blood directly for multiple organism groups. Multiplex screenings for bloodborne viral, bacterial and protozoan parasites using an open array platform have been currently described 22 . The open array platform customized with real-time PCR assays demonstrates a high level of multiplicity with sensitivity and specificity for detection of four viral, two bacterial and three protozoan blood-borne pathogens.…”