Significance of the isolation of Candida species from airway samples in critically ill patients: a prospective, autopsy study

Abstract

Recovery of Candida from the respiratory tract is common. Large series on the incidence of histologically proven Candida pneumonia in intensive care unit (ICU) patients are lacking. A two-year prospective study of all autopsies performed on patients who died in the ICU was conducted. For autopsy-proven cases of Candida pneumonia, we required microscopic demonstration of yeast invasion in lung autopsy specimens that showed inflammation. We looked for differences in incidence in patients with and without respiratory samples positive for Candida species pre-mortem. Of 1,587 patients admitted to the ICU, 301 (19%) died of whom 232 (77%) were autopsied. Of those, 135 patients (58%) had histopathological evidence of pneumonia. A total of 77 cases (57%) with pneumonia at autopsy had positive tracheal aspirate and/or BAL cultures for Candida spp. performed during the preceding two weeks. No cases of Candida pneumonia were identified amongst those 77 cases. In the other 58 patients with autopsy-proven pneumonia and no Candida isolation pre-mortem, no Candida pneumonia was observed either. Despite frequent isolation of Candida spp. from the airways, over a two-year period no single case of Candida pneumonia was found among the patients with evidence of pneumonia on autopsy. This study indicates that Candida pneumonia is an extremely rare occurrence in ICU patients and provides further evidence against the common use of antifungal therapy triggered by a microbiology report of Candida isolation from the respiratory tract.