This paper serves as a gateway review of several field and epidemiological investigations conducted across the United States (US) which have been compiled as a special supplement in a January 2011 number of the Clinical Infectious Diseases journal.

Respiratory specimens (i.e. lung, trachea, and large-airway specimens) collected at autopsy from people who died with pandemic influenza (H1N1) 2009 infection were submitted to CDC by medical examiners, hospitals, and local and state health departments for additional evaluation. A variety of microscopic and molecular methods were used to identify bacteria which found Streptococcus pneumonia (S. pneumoniae), Streptococcus pyogenes (S. pyogenes), Staphylococcus aureus (S. aureus), Streptococcus mitis (S. mitis), and Haemophilus influenzae (H. influenzae); four cases involved multiple pathogens.