Pseudomonas aeruginosa and Candida albicans interaction in the respiratory tract: from pathophysiology to a therapeutic perspective

Several studies evidenced a pathogenic interaction between P. aeruginosa and C. albicans. P. aeruginosa is one of the most frequent microorganisms responsible for ventilator-associated pneumonia (VAP) and C. albicans usually colonize tracheo-bronchial tract of patients undergoing mechanical ventilation in the intensive care unit. In vitro, P. aeruginosa exploits filamentous fungi resulting in fungal killing and limitation of C. albicans growth in the host. Biofilm also play an important role as a persistent source of infectious material for recurrent episodes of VAP. Indeed, Candida spp and P. aeruginosa are the most common pathogens retrieved from endotracheal tube biofilm and tracheal secretions in patients with VAP. Finally, it has been demonstrated that previous tracheo-bronchial C. albicans colonization enhanced the incidence of P. aeruginosa pneumonia in a murine model. A recent study performed in patients requiring intubation and mechanical ventilation identified Candida spp tracheo-bronchial colonization as a risk factor for P. aeruginosa VAP. In addition, a retrospective study suggested that antifungal treatment might reduce P. aeruginosa VAP or tracheo-bronchial colonization in intubated patients with Candida spp tracheo-bronchial colonization. These interactions have major environmental and medical consequences. Experimental studies providing a better understanding of the mechanisms of interaction and clinical studies evaluating the necessity of a antifungal treatment might improve the management of these opportunistic infections.