Molecular testing redefines sepsis diagnosis

October 5, 2020 0 By FM

Sepsis is a serious medical condition that arises when the body’s own response to infection can lead to tissue damage, organ failure and death, particularly if it is not identified early on and treated promptly. Sepsis is a race between the bugs that cause the disease and the immune system that often ends with the patient’s death. An estimated 47 mln to 50 mln sepsis cases and 11 million related deaths were reported worldwide in 2017. Unfortunately, 40% of the cases are among children under 5 years of age. The condition is a major cause of morbidity and mortality worldwide. Eighty-five percent of sepsis cases and 84.8% of sepsis-related deaths occur in countries with low, low-middle, or middle sociodemographic indices, particularly in sub-Saharan Africa and South-East Asia.

Sepsis and septic shock (severe sepsis causing organ failure and dangerously low blood pressure) can result from an infection anywhere in the body, including pneumonia, diarrheal disease, urinary tract infection, post-surgical infections etc. The infection could be acquired in a community setting or at healthcare facilities. Healthcare-associated infections are among the most common and are often resistant to antibiotics, which can worsen the clinical conditions.

Bacterial infections are the primary cause of sepsis. However, viruses and fungi are also known to cause it, especially in immunocompromised patients and those with other comorbidities. The prevention of sepsis in both community and healthcare facilities requires appropriate antibiotic treatment of the infection, the prompt availability of medical care, and an early detection of the bug or microbe causing it. The culture test (regarded as the gold standard currently) is widely used to grow bacteria and fungi. However, it takes a long time to produce actionable results. The inability of the culture technique to accurately identify the causative organism is another shortfall.

Speedy detection

To increase the speed of diagnosis, molecular detection techniques have been developed for bacterial, viral and fungal DNA, but they are not in widespread clinical use. Techniques like PCR (Polymerase Chain Reaction), microarray and Next Generation Sequencing (NGS) make use of the microbe’s genomic data. These techniques, apart from helping in detection, can also help identify if the pathogen is resistant to antibiotics. Multiplex and RT- PCR tests therefore hold great promise as far as overcoming the shortfalls of conventional tests like culture is concerned and provide higher speed and accuracy to detect and differentiate between multiple microbes in a single test. They also show high sensitivity which enables them to detect microbes in a sample even if it is present in very low quantities or loads. Speed is of pivotal importance for the diagnosis of sepsis, and hence, molecular techniques will be extremely useful for reducing hospitalisation and ICU stays, as well as for lowering mortality rates. 

The 2020 World Sepsis Day comes at a time when we are in the thick of the COVID-19 pandemic. The SARS-CoV2 virus can also cause sepsis, and therefore, raising awareness about sepsis is critical to saving lives. With COVID-19, there has come a general awareness about infectious diseases and molecular tests like RT-PCR, which is the gold standard for diagnosis of COVID-19. With the widespread development of infrastructure for molecular methods, it will be possible to extend the available technology and laboratory infrastructure to other critical infections, such as sepsis, which is both reversible and preventable.  

The author is Principal Scientist- Infectious Diseases at MedGenome Labs Ltd, Bangalore.