Swine influenza (H1N1) pneumonia in hospitalized adults: Chest film findings

In patients with swine influenza (H1N1) pneumonia, the admission chest film is critical to rapidly detect simultaneous bacterial pneumonia due to Staphylococcus aureus or subsequent bacterial pneumonia due to Streptococcus pneumoniae or Haemophilus influenzae by the presence of focal infiltrates. Our objective was to characterize the chest film findings in 25 adults hospitalized with H1N1 pneumonia during the pandemic and detect focal infiltrates indicative of bacterial coinfection, that is, bacterial pneumonia. Chest films were obtained on admission, after 48 hours, and thereafter as indicated throughout hospitalization. Chest film findings were classified as no infiltrates, clear with accentuated bibasilar lung markings, or focal segmental/lobar infiltrates. The presence or absence of pleural effusion and cavitation was also noted. Admitted adults with H1N1 pneumonia had negative chest films or accentuated basilar lung markings. After 48 hours, 13% of patients developed patchy bilateral interstitial infiltrates. No patients had or subsequently developed focal segmental/lobar infiltrates indicative of bacterial community-acquired pneumonia during hospitalization. The most common chest film finding was no infiltrates or an accentuation of bibasilar lung markings in hospitalized adults with H1N1 pneumonia. No patients had focal segmental/lobar infiltrates indicative of superimposed bacterial community-acquired pneumonia.