Candida in the Human Lung

In people with reasonably functional immune systems, Candida can still cause a number of health problems including digestive problems, increased risk for allergy, and infections to the urinary and sex organs. Candida albicans is the most common species of Candida in humans. Candida albicans is present in 2 forms- a yeast like single cell form, and a hyphal or chain-like form which generally has more virulence and invasiveness than the yeast form.

The role of Candida colonization/ infection in the human lung is not well understood. Candida species colonize the lungs of about half of all humans, the majority of which are asymptomatic1.    A study of 803 intensive care unit (ICU) patients reported that Candida lung colonization was associated with significantly longer duration of mechanical ventilation, significantly longer hospital stay, and significantly higher rates of Pneumonia due to Pseudomonas aeruginosa bacteria2.  Another study reported that Candida colonization was associated with a 2.5 fold increased risk of death in patients with VAP= ventilator associated pneumonia 3.  Chronic Candida lung colonization has also been associated with poorer lung function in cystic fibrosis patients 4.

Various animal studies have reported that combined lung infections involving both pathogenic bacteria (such as Staphylococcus aureus) and Candida have significantly higher mortality than infection with either pathogen alone 5.  The authors concluded that much more research is needed to study lung infections involving both pathogenic bacteria and Candida. 1.

References / Sources

1. Pendleton KM, Huffnagle GB, Dickson RP. The significance of Candida in the human respiratory tract: our evolving understanding. Pathogens and disease. 2017;75(3).

2. Azoulay E, Timsit JF, Tafflet M, et al. Candida colonization of the respiratory tract and subsequent pseudomonas ventilator-associated pneumonia. Chest. 2006;129(1):110-117.

3. Delisle MS, Williamson DR, Albert M, et al. Impact of Candida species on clinical outcomes in patients with suspected ventilator-associated pneumonia. Can Respir J. 2011;18(3):131-136.

4. Gileles-Hillel A, Shoseyov D, Polacheck I, Korem M, Kerem E, Cohen-Cymberknoh M. Association of chronic Candida albicans respiratory infection with a more severe lung disease in patients with cystic fibrosis. Pediatr Pulmonol. 2015;50(11):1082-1089.

5. Carlson E. Synergistic effect of Candida albicans and Staphylococcus aureus on mouse mortality. Infect Immun. 1982;38(3):921-924.

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