Candida Colonization of the Respiratory Tract and Subsequent Pseudomonas Ventilator-associated Pneumonia

Background: Recovery of Candida from the respiratory tract of a critically ill patient receiving mechanical ventilation (MV) usually indicates colonization rather than infection of the respiratory tract. However, interactions between Candida and bacteria, particularly Pseudomonas, have been reported. Thus, Candida colonization of the respiratory tract may predispose to bacterial ventilator-associated pneumonia (VAP).

Methods: In a multicenter study of immunocompetent critically ill patients receiving MV for > 2 days, we compared the incidence of pneumonia in patients with and without (exposed/unexposed) respiratory-tract Candida colonization, matched on study center, admission year, and MV duration.

Results: Over the 4-year study period, of the 803 patients meeting study inclusion criteria in the six study centers, 214 patients (26.6%) had respiratory tract Candida colonization. Candida albicans was the most common species (68.7%), followed by Candida glabrata (20.1%) and Candida tropicalis (13.1%). Extrapulmonary Candida colonization was more common in exposed patients (39.7% vs 8.3%, p = 0.01). Exposed patients had longer ICU and hospital stays but similar mortality to unexposed patients. The matched exposed/unexposed nested cohort study identified bronchial Candida colonization as an independent risk factor for pneumonia (24.1% vs 17.6%; adjusted odds ratio [OR], 1.58; 95% confidence interval [CI], 0.94 to 2.68; p = 0.0860); the risk increase was greatest for Pseudomonas pneumonia (9% vs 4.8%; adjusted OR, 2.22; 95% CI, 1.00 to 4.92; p = 0.049).

Conclusions: Candida colonization of the respiratory tract is common in patients receiving MV for > 2 days and is associated with prolonged ICU and hospital stays, and with an increased risk of Pseudomonas VAP.