Candida Colonization in the Respiratory Tract: What Is the Significance?

Candida spp. is one of the most important components of human microecology. Among hospitalized patients, the isolation rate of Candida spp. by active screening is about 15%, while in critically ill patients, the rate can be as high as 25% (1). Although microbial colonization plays an important role in secondary infections, Candida pneumonia is seldom documented even in the intensive care unit (ICU). Thus, the common consensus is that anti-Candida therapy is rarely necessary in most cases and it should be considered as colonization in which Candida spp. are isolated from the respiratory tract (RT) (2). The co-existence of bacteria and fungi has raised great concern in the last decade. It has been indicated by some studies that Candida colonization in the RT might be an independent risk factor that could promote ventilator-associated pneumonia (VAP) and even change the antibiotic resistance patterns of pathogenic bacteria by polymicrobial biofilm formation (3, 4). Therefore, the significance of Candida colonization in RT remains controversial, and many clinical problems need to be reinterpreted.