The human body contains 10 times more microbes than human cells; in fact, microbes make up one to three per cent of our body weight. These microbes — referred to as our microbiome — are vital to ensure proper functioning of our body.
Some microbes, called pathogens, can also cause infections. Bacteria and viruses are two very different types of pathogens that cause infections. Only about one per cent of all bacteria are pathogenic while almost all viruses can cause infections. They can cause a variety of illnesses, ranging from common cold to serious infections in vital organs. Diagnostics play an important role in treatment decisions for such infections.
Bacterial infections are treated with antibiotics while most viral infections get resolved on their own. In most cases, the symptoms and clinical signs of bacterial and viral infections can overlap, making it very difficult to decide on the course of treatment. So, a patient with viral infection may be prescribed antibiotics which are ineffective against viruses. In fact, a large study conducted by the School of Medicine at UCSF (USA) showed that out of 40 million people given antibiotics for respiratory conditions, 27 million did not require it. This is because most infections are treated without information about the identity of the infectious agent and antibiotic resistance in the pathogen.
This problem occurs in patients admitted to the ICU with severe infections. Here, patients are empirically treated with multiple broad-spectrum antibiotics, anti fungals, and anti virals. According to our study, almost all patients admitted in ICUs with Central Nervous System (CNS) infections were being treated with high level antibiotics, while only 28% of them had bacterial infections. Such indiscriminate use results in resistance to pathogens, rendering these life-saving drugs useless. Unnecessary antibiotic treatment could have other detrimental health effects that affect immunity and metabolism.
Many severe infections are a result of mixed infections, with bacteria and viruses. Here, it is important to treat using both antibiotics and antivirals. Hence, diagnosis is crucial in making rational treatment choices.
Conventional testing methods rely on culturing the pathogens from the clinical specimen, identifying them and then checking what antibiotics they are susceptible to. This is time consuming, taking up to 72 hours for bacteria and longer for fungi. Differences in the genetic material are exploited to identify pathogens where certain signature sequences specific to a particular organism are used to amplify its DNA. This method is called Polymerase Chain Reaction or PCR. PCR enables detection of pathogens and antibiotic resistance in a matter of hours as compared to days with traditional methods.
Highly sensitive multiplexed PCR assays are developed to detect over a 100 pathogens, including a variety of bacteria, fungi, viruses and parasites, as well as Antibiotic Resistance, within 8 hours. This allows evidence-based use of antimicrobials, which improve patient outcomes, including reduced morbidity and mortality, decreasing cost by lowering consumption of expensive third line drugs, and reducing hospital stay.