New DNA Test Quickly Identifies Secondary Infections in COVID-19 Patients with Double Risk of Developing Pneumonia

The simple DNA test developed by scientists and doctors at the University of Cambridge (Cambridge, UK) can quickly identify infections from bacteria and fungi that COVID-19 patients may acquire while in hospital - so called ‘ventilator-associated pneumonia’ - and target antibiotic treatment as needed.

Patients who need mechanical ventilation are at significant risk of developing secondary pneumonia while they are in intensive care. These infections are often caused by antibiotic-resistant bacteria, and are hard to diagnose and need targeted treatment. COVID-19 patients are thought to be at increased risk of infection for several reasons. Due to the amount of lung damage, these severe COVID-19 cases tend to spend more time on a ventilator than patients without COVID-19. In addition, many of these patients also have a poorly-regulated immune system, where the immune cells damage the organs, but also have impaired anti-microbial functions, increasing the risk of infection.

Normally, confirming a pneumonia diagnosis is challenging, as bacterial samples from patients need to be cultured and grown in a lab, which is time-consuming. The new test gives doctors the information they need to start treatment within hours rather than days, fine-tuning treatment as required and reducing the inappropriate use of antibiotics. This test takes an alternative approach by detecting the DNA of different pathogens, which allows for faster and more accurate testing. The test uses multiple polymerase chain reaction (PCR) which detects the DNA of the bacteria and can be done in around four hours, meaning there is no need to wait for the bacteria to grow. The test runs multiple PCR reactions in parallel, and can simultaneously pick up 52 different pathogens, which often infect the lungs of patients in intensive care. At the same time, it can also test for antibiotic resistance.

“Early on in the pandemic we noticed that COVID-19 patients appeared to be particularly at risk of developing secondary pneumonia, and started using a rapid diagnostic test that we had developed for just such a situation,” said co-author Dr. Andrew Conway Morris from Cambridge’s Department of Medicine and an intensive care consultant. “Using this test, we found that patients with COVID-19 were twice as likely to develop secondary pneumonia as other patients in the same intensive care unit.”

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