The Future of the Diagnosis of Disease

by Mia C

Recent medical advances in diagnostics have presented a faster and more accurate method of diagnosing pathogens within the blood through the process of melting DNA. It has been trialled with the aim of reducing the number of false positive and negative results that frequently present in blood cultures due to contaminations. With approximately 50% of all positive cultures found to contain contaminants. New methods of diagnostic testing are more important to prevent overprescription of antibiotics or incorrect treatment for disease.

A blood sample is taken and the DNA is isolated before it undergoes an universal digital

high-resolution melt. Here, the DNA undergoes a PCR process. The DNA is tagged with

fluorescent dye and is heated on top of a microfluidic chip to break hydrogen bonds holding

complementary strands together. The dye is released as the DNA unravels, producing a

melting curve which is recorded on a computer. A set of algorithms on the computer are able

to distinguish the difference between different melting curves of human and pathogenic DNA.

A PCR method can be used as an alternative to tracking the melting curve to specify the

pathogen. Here, the DNA can be put into reactant solutions on top of a micro fluidic chip

containing a variety of primers. Each primer is complementary to a specific base sequence

so attatches to the unwound DNA with complementary sequence order to identify pathogenic

DNA. The PCR method is arguably more accurate due to the specific base pairings being a

more accurate method of pathogen identification as opposed to graph analysis. However,

both provide diagnosis of disease at a faster rate than blood cultures.

This new method of analysing DNA to determine the presence of pathogens is especially

useful for the diagnosis of sepsis. Sepsis is an illness triggered by an infection during which

the body overreacts to the infection and starts harming its own tissues and organs. Sepsis

damages the body at a rapid rate causing traditional diagnosis methods of blood cultures to

be too slow for the speed of deterioration of the body. While blood cultures take around 15

hours to fully grown and analyse, methods of DNA melting are producing results of diagnosis

in under 6 hours. With higher accuracy due to not only a reduction in contamination but also

specifity of pathogen diagnosis from melting curves or PCR, these methods can produce

more reliable results at a faster rate to treat rapidly deteriorating infections, such as sepsis,

before they become fatal.

However, there are drawbacks to the new method of diagnosis of disease such as the

inability to diagnose new diseases. The computer algorithm diagnoses disease by matching

the pre-set melting curves with the melting curves from the DNA or primers to an already

known sequence of DNA in order to spot patterns to determine the pathogen. Therefore,

new diseases will be unable to be identified as information needs to be imputed prior to

analysis so it can be diagnosed.

Therefore, with current technologies and methods it is unlikely that DNA melting to produce

curves or for use in a PCR gene sequencing method will replace the current method of

diagnosis by blood cultures. However, as technology advances it is possible that methods of

diagnosis will transition towards

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