Bacterial pneumonia occurring with an influenza infection is very serious, according to Dr. Koenraad F van der Sluijs and colleagues at the Academic Medical Center, Amsterdam, The Netherlands.
The most prominent bacteria that causes pneumonia is Streptococcus pneumoniae. Other important pneumonia-causing bacteria are Staphylococcus aureus, Haemophilus influenzae, and Streptococcus pyogenes. “Individuals infected with influenza virus are most susceptible to secondary bacterial pneumonia between 4 and 14 days after the onset of influenza symptoms,” van der Sluijs reported.
Van der Sluijs explained that influenza infection damages the airways and leaves them more vulnerable to bacterial infection. “The severity of post-influenza pneumonia is due to virus-induced changes to the host that affect the course of bacterial infection.”
Historically, secondary bacterial pneumonia was believed to be responsible for most of the deaths from the 1918 “Spanish” influenza pandemic. During the later influenza pandemic of 1957, more than two-thirds of deaths were associated with bacterial pneumonia.