Bacterial Pathogens and Death during the 1918 Influenza Pandemic

Abstract

A review of recut lung-tissue specimens and published autopsy series from the 1918 influenza pandemic suggests that secondary bacterial pneumonia was an important cause of death, consistent with our preliminary analysis of antemortem blood cultures and the time to death of the patients. We review here studies that reported more than 10 sterile-site antemortem cultures from adults with pneumonia and those without pneumonia in an extensive archive of articles about the 1918 pandemic in any language. Bacteria were recovered in only a few blood cultures for patients who had influenza but not pneumonia (mean among all the reports, <1%) but were more commonly isolated from cultures of samples from patients with influenza-associated pneumonia (mean, 16%; range, 2 to 50), particularly those who died (40%). Moreover, 80% of pleural-fluid and lung cultures from patients with pneumonia yielded bacteria (range, 57 to 100). The studies with lower reported rates of positive culture may have obtained cultures early, overdiagnosed pneumonia, or had problems culturing fastidious organisms. Streptococcus pneumoniae and hemolytic streptococci (probably S. pyogenes) comprised 71% and 28% of positive cultures (whether blood or pleural and lung), respectively; Staphylococcus aureus was less common among the cultures (1%).