In Vitro Activities of Eight Antifungal Drugs against 104 Environmental and Clinical Isolates of Aureobasidium pullulans

Abstract

f Aureobasidium pullulans is an unusual agent of phaeohyphomycosis. The in vitro activities of antifungals against 104 isolates of Aureobasidium pullulans var. pullulans and A. pullulans var. melanigenum revealed low MIC 90 s of amphotericin B, posaconazole, and itraconazole. However, they were resistant to fluconazole (>64 g/ml) and had high MICs of voriconazole, isavuconazole, caspofungin, and micafungin.A ureobasidium pullulans is a common ubiquitously distributed melanized yeast-like fungus that is an occasional agent of phaeohyphomycosis (1). The genus Aureobasidium phylogenetically belongs to Ascomycota, order Dothideales, family Dothideaceae (2, 3). The clinically significant species are A. pullulans (4) and A. proteae (5); a case of Aureobasidium mansoni associated with cerebral phaeohyphomycosis (6) probably concerned a misidentification. The fungus commonly occurs in the hospital environment, where it colonizes moist surfaces, such as glass and metal, and has recently been reported to cause a varied spectrum of infections, including peritonitis, meningitis, and fungemia (1).Although Aureobasidium pullulans has been reported to be the most common species in over 32 cases of human phaeohyphomycosis infections, so far there are no systematic data on its antifungal susceptibility profiles. Furthermore, the fungus has not been identified to the species level in the majority of cases reported so far. Herein we report antifungal susceptibility profiles of 104 molecularly characterized isolates of Aureobasidium pullulans. The isolates were obtained from the reference centers Centraalbureau voor Schimmelcultures, Fungal Biodiversity Centre, Utrecht, The Netherlands, and the University of Texas Health Science Center, San Antonio, TX, USA. The strains included currently recognized varieties with their type strains: Aureobasidium pullulans var. pullulans (n ϭ 51) and A. pullulans var. melanigenum (n ϭ 53). Most strains originated from clinical (n ϭ 51) and environmental (n ϭ 47) samples, while 4 strains were from unknown sources (see Table S1 in the supplemental material). Most A. pullulans var. melanigenum strains (43 of 51) were recovered from clinical specimens, whereas Aureobasidium pullulans var. pullulans strains (40 of 51) were mainly isolated from the environment. Of the clinical A. pullulans var. melanigenum, 38 isolates (74.5%) were reported from cases of systemic infections in the United States. Species and variety identities were confirmed by sequencing the internal transcribed spacer region and the D1/D2 region of the nuclear large subunit rRNA gene (7).Antifungal susceptibility testing was performed in duplicate as per CLSI document M38-A2, with some modifications (8). Briefly, isolates were cultured on potato dextrose agar in the dark (25°C) for up to 7 days to induce sporulation. Inocula were prepared by scraping the surface of the fungal colonies with a cotton swab moistened with sterile physiological saline containing 0.05% Tween 40. Large particles were allowed to settle for 5 min, and then a su...

Candida tropicalis is the most prevalent yeast species causing candidemia in Algeria: the urgent need for antifungal stewardship and infection control measures

“…Interestingly, the isolate of C. orthopsilosis from the hands of a HCW may reinforce the hypothesis that, similar to C. parapsilosis, it may have been transferred from the hands of HCWs [40]. Moreover, isolation of A. melanogenum, N. albida, and N. liquefaciens from high touch areas, which are reported to have elevated MIC values to various antifungals [41][42][43] and finding Aureobasidium melanogenum in both blood and the environment are worrisome. Findings obtained from environmental screening and microsatellite typing may collectively imply the lack of proper hygiene (both hands and hospital environments) and necessitate the application of effective infection control strategies to eradicate/control fungemia caused by various yeast species.…”

Aureobasidium pullulans place among human pathogens opportunistic infections (literature review)

“…В исследовании M. Javad Najafzadeh и соавт. [19] изучена чувствительность 104 штаммов A. pullulans (51 штамм из клинического материала) после идентификации на молекулярно-генетическом уровне. Амфотерицин В, итраконазол и позаконазол были признаны препаратами с наилучшей активностью против A. pullulans.…”

Aureobasidium pullulans-Associated Invasive Mycosis in a Child with Acute Myeloblastic Leukemia: A Case Report

“…[3]. К настоящему времени описано немногим более 30 случаев феогифомикоза у человека, обусловленного A. pullulans [4].…”

“…В исследовании M.J. Najafzadeh и соавт. [4] изучена чувствительность 104 штаммов A. pullulans (51 штамм из клинического материала) после идентификации на молекулярногенетическом уровне. Амфотерицин В, итраконазол и позаконазол были признаны препаратами с наилучшей активностью против A. pullulans.…”