A new DNA test will quickly identify secondary infections in COVID-19 patients

Researchers have developed a DNA test to quickly identify secondary infections in COVID-19 patients, who are twice as likely to develop bone marrow failure while ventilated in non-COVID patients. no COVID-19.

For patients with the most severe forms of COVID-19, mechanical ventilation is the only way to keep them alive, as doctors use anti-inflammatory medications to treat their inflamed lungs. However, these patients are susceptible to other infections from bacteria and fungi that they may get while in hospital – known as ‘shower-related pneumonia’.

Now, a team of scientists and doctors at the Cambridge and Cambridge University Hospitals NHS Foundation Trust, led by Professor Gordon Dougan, Dr Vilas Navapurkar, and Dr Andrew Conway Morris, have developed a simple DNA test to identify and target these diseases. antibiotic treatment as needed.

The trial, developed at Addenbrooke’s hospital in collaboration with Public Health England, gives doctors the information they need to start treatment within hours rather than days, tuning treatment as needed and reducing inappropriate use of antibiotics.

This approach, based on higher capacity DNA testing, is being introduced at Cambridge University Hospitals and offers a pathway to better treatments for disease in general. The results are reported in the journal Critical Care.

Patients who require mechanical ventilation are at high risk for developing secondary pneumonia while under intensive care. These infections are often caused by antibiotic-resistant bacteria, are difficult to diagnose, and require targeted treatment.

Early in the pandemic we noticed that COVID-19 patients appeared to be particularly at risk of developing secondary influenza seizures, and we began using a rapid diagnostic test that we had development for just such a situation. Using this test, we found that patients with COVID-19 were twice as likely to develop secondary pneumonia than other patients in the same intensive care unit. “

Dr Andrew Conway Morris, Co-Author of Research and and Intensive Care Adviser, Department of Medicine, University of Cambridge

COVID-19 patients are thought to be at increased risk for infection for a number of reasons. Because of the extent of lung damage, these COVID-19 severe cases tend to spend more time on airway than patients without COVID-19.

In addition, many of these patients also have an immune system, where the immune cells damage the organs, but also have antimicrobial actions, increasing the risk of infection.

Determining the diagnosis of pneumonia is usually challenging, as bacterial samples from patients need to be cultivated and grown in a laboratory, which takes time. The Cambridge test uses another method of detecting the DNA of various pathogens, which allows for faster and more accurate testing.

The test uses polymerase chain reaction (PCR) that detects the bacteria’s DNA and can be performed in about four hours, meaning there is no need to wait for the bacteria to grow. “Often, patients have already started receiving antobiotics before the bacteria had time to grow in the laboratory,” Morris said.

“This means that results from cultures are often negative, but PCR does not require viable bacteria to detect it – doing a more accurate test.”

The test – developed by Dr Martin Curran, an expert in PCR diagnostics from Cambridge Health Public England’s laboratory – runs several PCR reactions in parallel, and can detect 52 different pathogens at the same time, which often affects the lungs of patients undergoing intensive care. At the same time, it can also test for antibiotic resistance.

“We found that while patients with COVID-19 were more likely to develop secondary pneumonia, the bacteria that caused these infections were similar to those in ICU patients without COVID-19,” said lead author Malis Maes, also from the Department of Medicine. “This means that standard antibiotic protocols can be applied in COVID-19 patients.”

This is one of the first times this technology has been used in routine clinical practice and is now hospital-approved. The researchers anticipate that similar approaches would benefit patients if used more widely.