Nourrisson Céline, Moniot Maxime, Lavergne Rose-Anne, Robert Estelle, Bonnin Virginie, Hagen Ferry, Grenouillet Frédéric, Cafarchia Claudia, Butler Geraldine, Cassaing Sophie, Sabou Marcela, Le Pape Patrice, Poirier Philippe, Morio Florent
Université Clermont Auvergne, Inserm, 3IHP, Centre Hospitalier Universitaire Clermont-Ferrand, Service de Parasitologie-Mycologie, Clermont-Ferrand, France; Université Clermont Auvergne/Inserm U1071, USC-INRAe 2018, Microbes, Intestin, Inflammation et Susceptibilité de l'Hôte, Clermont-Ferrand, France.
Université Clermont Auvergne, Inserm, 3IHP, Centre Hospitalier Universitaire Clermont-Ferrand, Service de Parasitologie-Mycologie, Clermont-Ferrand, France.
Clin Microbiol Infect. 2023 Feb;29(2):257.e7-257.e11. doi: 10.1016/j.cmi.2022.09.021. Epub 2022 Oct 7.
Diutina (Candida) catenulata is an ascomycetous yeast isolated from environmental sources and animals, occasionally infecting humans. The aim of this study is to shed light on the in vitro antifungal susceptibility and genetic diversity of this opportunistic yeast.
Forty-five D. catenulata strains isolated from various sources (including human and environmental sources) and originating from nine countries were included. Species identification was performed using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry and confirmed via internal transcribed spacer ribosomal DNA barcoding. In vitro antifungal susceptibility was determined for seven systemic antifungals via the gradient strip method after 48 hours of incubation at 35°C using Etest® (Biomérieux) or Liofilchem® strips. Isolates exhibiting fluconazole minimal inhibitory concentrations (MICs) of ≥8 μg/mL were investigated for mutations in the ERG11 gene. A novel microsatellite genotyping scheme consisting of four markers was developed to assess genetic diversity.
MIC ranges for amphotericin B, caspofungin, micafungin, isavuconazole, and posaconazole were 0.19-1 μg/mL, 0.094-0.5 μg/mL, 0.012-0.064 μg/mL, 0.003-0.047 μg/mL, and 0.006-0.032 μg/mL, respectively. By comparison, a broad range of MICs was noted for fluconazole (0.75 to >256 μg/mL) and voriconazole (0.012-0.38 mg/L), the higher values being observed among clinical strains. The Y132F amino acid substitution, associated with azole resistance in various Candida species (C. albicans, C. tropicalis, C. parapsilosis, and C. orthopsilosis), was the main substitution identified. Although microsatellite typing showed extensive genetic diversity, most strains with high fluconazole MICs clustered together, suggesting human-to-human transmission or a common source of contamination.
The high rate of acquired fluconazole resistance among clinical isolates of D. catenulata is of concern. In this study, we highlight a link between the genetic diversity of D. catenulata and its antifungal resistance patterns, suggesting possible clonal transmission of resistant isolates.
链状念珠菌是一种从环境源和动物中分离出的子囊菌酵母，偶尔会感染人类。本研究的目的是阐明这种机会性酵母的体外抗真菌药敏性和遗传多样性。
纳入了从九个国家的各种来源（包括人类和环境来源）分离出的45株链状念珠菌菌株。使用基质辅助激光解吸/电离飞行时间质谱进行菌种鉴定，并通过内转录间隔区核糖体DNA条形码进行确认。在35°C孵育48小时后，使用Etest®（生物梅里埃公司）或Liofilchem®试纸条通过梯度条法测定七种全身用抗真菌药的体外抗真菌药敏性。对氟康唑最低抑菌浓度（MIC）≥8μg/mL的分离株进行ERG11基因突变研究。开发了一种由四个标记组成的新型微卫星基因分型方案来评估遗传多样性。
两性霉素B、卡泊芬净、米卡芬净、艾沙康唑和泊沙康唑的MIC范围分别为0.19 - 1μg/mL、0.094 - 0.5μg/mL、0.012 - 0.064μg/mL、0.003 - 0.047μg/mL和0.006 - 0.032μg/mL。相比之下，氟康唑（0.75至>256μg/mL）和伏立康唑（0.012 - 0.38mg/L）的MIC范围较宽，在临床菌株中观察到较高的值。与各种念珠菌属（白色念珠菌、热带念珠菌、近平滑念珠菌和正平滑念珠菌）中的唑类耐药相关的Y132F氨基酸替代是鉴定出的主要替代。尽管微卫星分型显示出广泛的遗传多样性，但大多数氟康唑MIC高的菌株聚集在一起，表明存在人传人传播或共同的污染源。
链状念珠菌临床分离株中获得性氟康唑耐药率较高令人担忧。在本研究中，我们强调了链状念珠菌的遗传多样性与其抗真菌耐药模式之间的联系，提示耐药分离株可能存在克隆传播。
