TRENDS IN MOLECULAR DIAGNOSTICS OF INFECTIOUS DISEASES

Infectious diseases are caused by the pathogenic microorganisms such as bacteria, viruses, parasites, and fungi are the major cause of deaths especially in developing and underdeveloped countries. The major infectious disease caused by bacteria includes pneumonia, and tuberculosis which are among the top 10 causes of death, various infectious diseases caused by the virus include HIV, hepatitis, influenza, Zika, Ebola etc.

The recent outbreaks of viral diseases like the Ebola, Zika and Corona virus have increased the demand for rapid detection kits which can help in identifying infected individuals and help in curtailing spread of disease and improve treatment outcomes. For these diseases, the previous techniques used for the detection was based on cultural studies which took up-to 5-6 days resulting in many disadvantages like contamination in the culture and increase in the incidence and mortality rate due to the delay in the detection and start of treatment. Alternatively, molecular diagnostic techniques (MDx) have reduced the detection and diagnosis period of the pathogen by sequencing the blood sample of the infected person. For example, the DNA based methods like PCR, NGS, micro-array and FISH even though cannot be performed in short time-interval; they can provide reliable and sensitive results. Likewise, these tests not only identify the species but also can identify the drug target site for the treatment. There are major development in research and development of molecular diagnostic kits such as AccuPower ZIKVMultiplex Real-Time PCR Kit designed for the detection of the ZIKA virus.

Simultaneously, the current trend is the development of point-of-care tests (POC), which can detect the presence of the pathogens instantly by non-invasive methods where a few drops of the body fluids such as blood and urine sample are required. Similarly, POC has another advantage like; these tests can be easily carried and performed in isolated places like severely under-developed regions where there is a lack of hospital care and sophisticated instruments for detection. Due to these factors, people are moving from traditional methods to molecular diagnostic technologies and in case of HIV a leading viral disease, can be now detected early as possible with the rapid detection tests that can identify the presence of the pathogen even before the symptoms can be seen, and targeted therapies can be given at an early stage. So many companies are investing and producing assay based tests to detect as early as possible. For example, Gen-Probe’s (APTIMA) HIV-1 RNA qualitative assay is the only molecular assay that is FDA approved for the diagnosis of acute infections and as a confirmatory test for diagnosing HIV-1 in samples. Similarly, in case of tuberculosis (TB) the introduction of MDx has helped in controlling resistance to the anti-biotic drugs and reduction in the number of deaths. For instance, Xpert MTB/RIF (Danaher Corporation, U.S) Amplified Mycobacterium Tuberculosis Direct (MTD) kits are used for the detection of the pathogen.

Over the past decade, molecular diagnostics has become a viable alternative due to its current trend like the development of the de-centralized laboratories instead of hospitals for infectious diseases testing and has emerged as a valuable weapon in the battle against antibiotic resistance and hospital acquired infections. For example, Methicillin resistant Staphylococcus aureus (MRSA), a type of

Staphylococcus aureus which is resistant to Methicillin and other antibiotics, can be detected using Xpert MRSA/SA BC test (Cepheid Inc, U.S.), a whole genome sequencing method by targeting the genomic material unique to each pathogen, molecular tests can deliver diagnostic results much quicker and, in many cases, more accurately than conventional culture-based techniques. The clinical value of rapid molecular diagnostics is underscored by the time-sensitive nature of many of the treatment decisions associated with infectious diseases. As the emergence and spread of antimicrobial resistance continue globally and the supply of available antibiotics continues to dwindle rapid molecular diagnostics have proven to be a vital tool in controlling spread of antibiotic resistant pathogens.

In the coming years, the adoption and development of molecular diagnostic tests will have major impact in controlling spread of infectious diseases.

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