Yarrowia lipolytica as Normal Human Flora

Background Yarrowia lipolytica, previously named Candida lipolytica, is a yeast species that has been reported as a human colonizer and a weak human pathogen. Most clinical reports involve catheter-associated fungemia, which clears with removal of the catheter alone or with addition of intravenous amphotericin B. No fatalities or poor outcomes have been associated with infection by this organism. Methods We reviewed microbiological data from our laboratory for growth of Y lipolytica from any clinical specimen between 2000 and 2010. Results Seventeen of the 24 patients grew Y lipolytica from lung tissue after resection of a lung mass suspicious for malignancy. Only two of these specimens were positive for malignancy, and most of the samplesgrew additional bacterial isolates. Other specimens that grew Ylipolytica included a stool sample, duodenal mass, breast tissue, a mesenteric mass, and 2 cutaneous nodules. Only 1 bronchoalveolar lavage sample grew the organism, and it did not grow from sputum. None of our 24 patients were found to have associated fungemia. No patients had evidence that Y lipolytica was responsible for active disease. Antifungal therapy was not initiated for any of these positive cultures. Conclusions The findings suggest that Y lipolytica should be considered normal human flora, especially of the adult respiratory tract. Given its prevalence in distal lung tissue, rather than more proximal sputum specimens or bronchoalveolar lavage, the organism may be present as a distal airway saprophyte with little clinical significance. Physicians should recognize the benign nature of this organism and formulate their treatment strategies accordingly.