Invasive pulmonary aspergillosis and influenza co-infection in immunocompetent hosts: case reports and review of the literature

Invasive pulmonary aspergillosis (IPA) is classically considered an illness of severely immunocompromised patients with limited host defenses. However, IPA has been reported in immunocompetent but critically ill patients. This report describes two fatal cases of pathologically confirmed IPA in patients with influenza in the intensive care unit. One patient had influenza B infection, whereas the other had influenza A H1N1. Both patients died despite broad-spectrum antimicrobials, mechanical ventilation, and vasopressor support. Microscopic and histologic postmortem examination confirmed IPA. Review of the English language and foreign literature indicates that galactomannan antigen testing and classic radiologic findings for IPA may not be reliable in immunocompetent patients. Respiratory cultures which grow Aspergillus species in critically ill patients, particularly those with underlying influenza infection, should not necessarily be disregarded as contaminants or colonizers. Further research is needed to better understand the immunological relationship between influenza and IPA for improved prevention and treatment of influenza and Aspergillus co-infections.