Joost Wauters- Ziekenhuis University (Leuven, Belgium)
Invasive pulmonary aspergillosis (IPA) typically occurs in a severely immunocompromised host and isolation of Aspergillus species in the immunocompetent host is mostly considered colonization. Overall, the six-week mortality of IPA is around 20-30% but it is much higher in critically-ill patients. Influenza is a common viral respiratory tract infection. In a subset of patients with influenza, intensive care admission is needed. This may be due to bacterial superinfection, but also influenza in itself can cause severe acute respiratory distress syndrome (ARDS),which is associated with a mortality rate of 14% to 41%.
Influenza-associated aspergillosis (IAA) was occasionally described decades ago and several small case series were reported recently. 65% of the reported cases did not have classic host factors for IPA as defined by the EORTC/MSG. We recently conducted a large retrospective multicentre cohort study, finding that IPA was diagnosed in 19% (83/432) of 432 evaluable patients admitted to the ICU with severe influenza. The prevalence of IPA in the 117 immunocompromised influenza patients was as high as 32% (38/117), while 14% (45/315) non-immunocompromised influenza patients developed IPA. In contrast, only 5% (16/315) of the non-immunocompromised influenza-negative controls developed IPA (p<0·001). The 90-day mortality in influenza patients with and without IPA was 51% and 28%, respectively (p<0·001). In the retrospective cohort study, influenza was found to be independently associated with IPA (aOR 5·2, 95% CI 2·6 to 10·3, p<0·001), besides a higher APACHE II score, male sex and the use of corticosteroids.
Severe influenza was thus identified as a novel independent risk factor for IPA and was associated with a high mortality. Future studies should evaluate whether faster diagnosis and/or antifungal prophylaxis could improve outcome of influenza-associated aspergillosis. More research is also needed concerning the pathophysiology of this exciting co-infection.