Pulmonary Aspergillosis in Patients with Suspected Ventilator-associated Pneumonia in UK Intensive Care Units

RATIONALE: Aspergillus infection in patients with suspected ventilator-associated pneumonia remains uncharacterised due to absence of a disease definition and limited access to sensitive diagnostic tests.

OBJECTIVES: To estimate the prevalence and outcomes of Aspergillus infection in adults with suspected ventilator associated pneumonia.

METHODS: Two prospective UK studies recruited 360 critically ill adults with new or worsening alveolar shadowing on chest X-ray and clinical/haematological parameters supporting suspected ventilator-associated pneumonia. Stored serum and bronchoalveolar lavage fluid were available from 194 non-neutropenic patients and underwent mycological testing. Patients were categorized as having probable Aspergillus infection using a definition comprising clinical, radiological and mycological criteria. Mycological criteria included: positive histology or microscopy; positive bronchoalveolar lavage fluid culture; galactomannan optical index ≥1 in bronchoalveolar lavage fluid or ≥0·5 in serum.

MEASUREMENTS AND MAIN RESULTS: Of 194 patients evaluated, 24 met the definition of probable Aspergillus infection, giving an estimated prevalence of 12·4% (95% CI 8·1-17·8). All 24 patients had positive galactomannan in serum (n=4), bronchoalveolar lavage fluid (n=16), or both (n=4); three patients cultured Aspergillus sp. in bronchoalveolar lavage fluid. Patients with probable Aspergillus infection had significantly longer median duration of critical care stay (25·5vs15·5 days, p=0·02). ICU mortality was numerically higher in this group although was not statistically significant (33·3%vs22·8%, p=0·23).

CONCLUSIONS: The estimated prevalence for probable Aspergillus infection in this geographically dispersed multicentre UK cohort indicates that this condition should be considered when investigating patients with suspected ventilator-associated pneumonia, including patient groups not previously recognised to be at high risk of aspergillosis.