Apr 3, 2020

Does antibiotic resistance matter in a viral pandemic?

Scanning electron micrograph of Staphylococcus aureus

At first sight, a viral disease such as covid-19 has little to do with antibiotic resistance. Those who remember their biology classes will know that antibiotics work only to treat bacterial infections. Against viruses we need different kinds of drugs called antivirals (and of course vaccines), and when these are not available we can only try to limit the spread by other means such as social distancing.

However, there can be a connection between the occurrence of resistant bacteria and how bad a viral pandemic becomes. This is because of secondary infections: when a patient is already sick with one infection, it can be easier for another pathogen to infect them as well. A well-known example is how a common cold, caused by a virus, can lead to secondary bacterial pneumonia.

Norwegian researchers Eiliv Lund and Tonje Braaten recently published an opinion piece in Dagens Naeringsliv, arguing that the variation in mortality for covid-19 patients between different European countries could be linked not only to population density and demographics, but also to how common antibiotic resistance is. Italy has a lot of resistant bacterial infections on hospitals, which means a patient that is hospitalized for covid-19 in Italy is at risk of catching a resistant secondary infection. In Norway, on the other hand, that risk would be very small. This difference could lead to a significant difference in survival rates of hospitalized patients.

While it is too early to know the importance of resistant bacteria in the ongoing pandemic, there are previous studies that indicate that secondary infections increase morbidity (severity) and mortality in influenza pandemics. An article in The Journal of Infectious Diseases from 2008 concludes that the majority of deaths in the Spanish flu, which occurred before antibiotics were introduced, likely resulted directly from secondary bacterial pneumonia. Another paper in BMC Infectious Diseases from 2018 on the 2009 influenza pandemic found that in  studies that reported on bacterial complications, secondary bacterial infection was identified in almost one in four patients and were associated with serious outcomes such as death and admission to intensive care.

Covid-19 may be different; we should not jump to conclusions. The role of bacterial infections and antibiotic resistance in this pandemic will, however, be an important subject to investigate in the coming years. Viral infections are more likely than bacteria to cause global pandemics, but addressing antibiotic resistance could still turn out be extremely important for limiting their severity and preventing deaths.

Viral infections are more likely than bacteria to cause global pandemics, but addressing antibiotic resistance could still turn out be extremely important for limiting their severity and preventing deaths.

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