What causes secondary bacterial pneumonia in influenza?

Updated: Aug 07, 2020
  • Author: Hien H Nguyen, MD, MS; Chief Editor: Michael Stuart Bronze, MD  more...
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Secondary bacterial pneumonia can occur from numerous pathogens (eg, Staphylococcus aureus, Streptococcus pneumoniae, and Haemophilus influenzae). The most dreaded complication is staphylococcal pneumonia, which develops 2-3 days after the initial presentation of viral pneumonia. Patients appear severely ill, with productive bloody cough, hypoxemia, an elevated white blood cell (WBC) count, and multiple cavitary infiltrates on chest radiography. [28]

A study from Israel found an increase in S pneumoniae bacteremia during regular influenza seasons; in addition, during the 2009-2010 H1N1 influenza pandemic, there were higher rates of Spneumoniae bacteremia among children (but not among adults) and higher rates of S aureus and Streptococcus pyogenes infections in all age groups. [29]

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