Watch for influenza-associated aspergillosis (IAA) in critically ill patients
October 31 2017
Influenza-associated aspergillosis (IAA) is a well-known condition among immunocompromised patients, but there is less awareness of its role as a complication in critically ill patients. It is likely to be underdiagnosed: only 68 cases were reported in the literature prior to 2017, with a mortality rate of 47%. However, in a recent letter to the editor of American Journal of Respiratory and Critical Care Medicine, the Dutch-Belgian Mycoses Study Group described a further 23 cases of IAA in the Netherlands alone over a four month period (Dec 2015 to April 2016) with a mortality rate of 61%. The authors suggest that delays in diagnosing and initiating antifungal therapy may have contributed to this rate.
In this study, each patient at eight academic ICUs who had been diagnosed (by rtPCR) with influenza was assessed retrospectively for clinical and microbiological evidence of invasive aspergillosis. Of 144 influenza patients studied, 23 (16%) also had aspergillosis, and 14 of those (61%) died during while admitted to the ICU. Previously-reported cases were generally associated with influenza A H1N1, but these cases were a mixture of H1N1, NT and influenza B. The clinical presentation was somewhat different from more typical cases of aspergillosis, and not all patients had obvious risk factors or underlying disease. Worryingly, 30% of IAA patients tested were infected with aspergillus strains showing resistance to azoles.
Another recent paper looked at rates of co-infection in ICUs in Spain between 2009 and 2015. Of 2901 patients included in the study, 482 (17%) suffered from a co-infection, of which 35 (1%) were co-infected with Aspergillus spp. Co-infection with Aspergillus did not show a clear change in incidence during this period, but it was associated with a significantly greater mortality rate (aOR 4.1, 95 % CI 1.9–9.6; P = 0.001).
Mortality could potentially be reduced through increased awareness among ICU staff of the signs of IAA:
- Radiological findings: cavitary lesions, nodules, air-crescent signs
- Diagnostic tests: galactomannan in serum or bronchoalveolar lavage
- Clinical signs: dyspnea, haemoptysis or pleural friction rub
- Worsening of respiratory insufficiency despite more >3 days of antibiotic therapy