Molecular diagnosis and source tracing of an infection of Aureobasidium pullulans

Aureobasidium pullulans (A. pullulans) is a dematiaceous, yeast-like fungus that is ubiquitous in nature, which can colonize the human hair and skin. A. pullulans has been clinically implicated to cause skin and soft tissue infections, meningitis, splenic abscesses, and peritonitis. Herein, molecular diagnostic of internal transcribed spacer (ITS) sequencing was used to investigate a suspected case of A. pullulans infection, and the infection source had been traced. A 27-year-old female case was suspected of kala-azar due to the recurrent fever. Bone marrow specimens were analyzed. The samples were negative for Leishmania, Penicillium marneffei and Histoplasma capsulatum. DNA was extracted from the bone marrow specimens, and the 583-bp sequence was amplified with the fungal ITS universal primers. The sequence was compared by Blast query to be identified as A. pullulans. A strain of A. pullulans was also isolated from the kitchen of the patient's living room. Culture characteristics were the same as the human pathogens of A. pullulans, and the ITS sequence was identical to the bone marrow ITS amplification. In conclusion, a deep infection caused by A. pullulans is rare, often occurring in the indwelling catheter, which may cause peritonitis and other symptoms. ITS sequencing of fungi can be used as a diagnostic reference. As A. pullulans is a common fungus in environment, amplification of ITS sequence of A. pullulans in the aseptic body fluid would be necessary to make a comprehensive diagnosis based on the clinical symptoms and signs.