DNA test can diagnose COVID patients with pneumonia in hours—usual exam can take days

A team of scientists and doctors developed a DNA test that they say can more quickly diagnose hospitalized COVID-19 patients with other infections, such as pneumonia, while on a mechanical ventilator battling for their life.

The test can simultaneously detect up to 52 different respiratory pathogens within hours, as well as any signs of antibiotic resistance in the body, according to the researchers, reducing the misuse of antibiotics and the amount of waiting time before patients start accurate treatment.

It uses the same polymerase chain reaction (PCR) technology as the traditional nasal swab exams to diagnose people with COVID-19. Results are ready in about four hours after the tests spot bits of a bacteria’s DNA.

The exam is rolling out in Cambridge University Hospitals in England. A study on the test was published Monday in the journal Critical Care.

“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,” study co-author Dr. Andrew Conway Morris, an intensive care consultant at Cambridge’s Department of Medicine, said in a news release.

Traditionally, a pneumonia diagnosis comes only after patient lung fluid samples are placed in a lab dish that scientists analyze several days later to check for growth, a “time-consuming” process, the researchers noted.

As experts wait for the results, patients are sometimes given antibiotics before doctors know exactly what they are trying to treat. Morris said this makes the DNA test, which also uses fluid lung samples, a more accurate exam because it “doesn’t need viable bacteria” to diagnose the patient’s illness.

The team studied 81 COVID-19 patients and 144 non-COVID-19 patients receiving ventilation in one England hospital between March 15 and Aug. 30.

While using the test, the team learned that COVID-19 patients on a ventilator were twice as likely to develop secondary pneumonia as other patients without the disease within the same intensive care unit. This is “partly, but not entirely due to” longer time spent on a ventilator because of extensive lung damage from the disease, the researchers said.

The machine itself can also introduce more opportunities for infection with pathogens, such as “ventilator-associated pneumonia,” which happens when germs enter the breathing tube placed down a patient’s throat and get into their lungs.

What’s more, these germs are often resistant to antibiotics, making them harder to diagnose and target for treatment.

Coronavirus patients are also more at risk of infection is because their immune systems are too busy battling COVID-19, meaning their defenses against other pathogens are weaker than usual.

With up to 80% of coronavirus patients admitted to the ICU requiring mechanical ventilation, the researchers say faster, more accurate testing can prevent further secondary infections during their bout with the disease.