Researchers have developed a DNA test to quickly identify secondary infections in COVID-19 patients who have double the risk of catching pneumonia while on ventilation.
For patients with the most severe forms of COVID-19, mechanical ventilation is often the only way to keep them alive as doctors use anti-inflammatory therapies to treat their inflamed lungs. However, these patients are susceptible to further infections from bacteria and fungi that they may acquire while in hospital.
A team of scientists and doctors at the University of Cambridge and Cambridge University Hospitals NHS Foundation Trust, led by professor Gordon Dougan, Dr Vilas Navapurkar and Dr Andrew Conway Morris, have developed a DNA test to quickly identify these infections and target antibiotic treatment as needed.
The test, 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, fine-tuning treatment as required and reducing the inappropriate use of antibiotics.
This approach, based on higher throughput DNA testing, is being rolled out at Cambridge University Hospitals. The results are reported in the journal Critical Care.
Conway Morris said: “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.
“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.”
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.
Morris added: “Often, patients have already started to receive antibiotics before the bacteria have had time to grow in the lab. This means that results from cultures are often negative, whereas PCR doesn’t need viable bacteria to detect – making this a more accurate test.”
The test – which was developed with Dr Martin Curran, a specialist in PCR diagnostics from Public Health England’s Cambridge laboratory – 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.
Lead author Mailis Maes said: “We found that although 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.
“This means that standard antibiotic protocols can be applied to COVID-19 patients.”
This study was funded by the National Institute for Health Research Cambridge Biomedical Research Centre.