Although COVID-19 is a respiratory disease caused by a virus, many patients with weakened immune systems find themselves at high risk of developing bacterial co-infections. What’s more, because doctors have caught on to this, the use of antibiotics as standard treatment for COVID-19 could cause a sharp rise in antimicrobial resistance, researchers at Queen’s University Belfast warn.

Professor José Bengoechea and Dr. Connor Bamford, both microbiologists at Queen’s Wellcome-Wolfson Institute for Experimental Medicine, recently published a new study in which they argue that COVID-19 patients face tremendous risks of developing severe bacterial infections.

According to the pair of microbiologists, clinical data and postmortem analyses of tissue from deceased COVID-19 patients indicate the presence of bacterial co-infections localized in the lungs.

They also argue that the immune system responds differently to SARS-CoV-2 (the coronavirus that causes COVID-19) when the body is simultaneously attacked by a bacterial infection, resulting in worse clinical outcomes and disease severity.

In light of such considerations, the researchers urge medical staff to exercise great caution and be mindful of the risks of bacterial co-infections, especially in a hospital setting where this can happen easily.

“The lack of therapies to treat severe COVID-19 patients led clinicians to use a number of treatments to modify the activity of their immune system,” Bengoechea said in a statement.

“However, it is important to note that these interventions may also increase the risk of potentially fatal secondary bacterial respiratory infections. Therefore, careful consideration should be given whether any potential new therapy may affect the patients’ defenses against bacterial infections. We believe that there is an urgent need to Ben develop new therapeutics to treat COVID-19 targeting the virus/bacteria co-infection scenario.”

The study also raises concerns regarding the impact of COVID-19 on antimicrobial resistance. In most hospitals, the most severe cases of COVID-19 are treated with broad-spectrum antibiotics. According to Bengoechea and Bamford, not only do such antibiotics do little to improve patient outcomes, they’re actually correlated with higher mortality.

“We are still in the early days of the COVID-19 pandemic and are learning more about this virus and disease every day. One of the most worrying aspects emerging is the association with bacterial and other microbial co-infections in the sickest patients,” Bamford said.

“Our research suggests that bacterial infection alongside the virus is likely to make the COVID-19 worse, although we don’t yet know the true extent. The rise of antimicrobial resistance in bacteria means this situation is harder to treat. It is clear that we will need new drugs that take into consideration both the virus and the bacteria.”

The findings appeared in the journal EMBO Molecular Medicine.