Gómez-Molero Emilia, Willis Jesse R, Dudakova Anna, Carreté Laia, Weig Michael, Groß Uwe, Gácser Attila, Gabaldón Toni, Bader Oliver
Institute for Medical Microbiology, University Medical Center Göttingen, Göttingen, Germany.
Comparative Genomics Group, CRG-Centre for Genomic Regulation, Barcelona, Spain.
Front Microbiol. 2020 Aug 27;11:1994. doi: 10.3389/fmicb.2020.01994. eCollection 2020.
The human pathogenic yeast has gained significant importance over the past decades as one of the principal causes of fungal bloodstream infections. Isolates of are known to be able to switch between several different colony morphologies in vitro, which are correlated with different cell shapes, altered cell surface properties, and thus different capacities to form biofilms on indwelling medical devices. In a set of six clinical specimens from a single surgery patient yielding stable smooth- as well as crepe-morphology isolates, we investigated the differences between five of them on a phenotypic and genomic level. In contrast to the initial assumption that they were switched forms of a clonal strain, karyotyping and genome sequencing showed that the patient was colonized by at least three distinct linages. Statistical analysis placed these groups distantly across the population of . Interestingly the single blood culture isolate was of smooth morphology and matched with an isolate from the patient's nose of similar morphology. Strong variation between the isolates was seen in adhesin-encoding genes, where repeat regions showed significant variation in length and repeat-numbers, most strikingly in of the smooth isolates. Although no differences in drug susceptibility were evident, the high phylogenetic distance separating the individual strains highlights the need for testing of multiple colonies in routine practice. The absence of biofilm formation in the blood stream isolate indicates a lack of respective adhesins in the cell wall, in turn pointing toward lack of adhesion as a positively contributing factor for dissemination.
在过去几十年中，人类致病性酵母已成为真菌血流感染的主要原因之一，具有重要意义。已知该酵母的分离株能够在体外几种不同的菌落形态之间转换，这些形态与不同的细胞形状、改变的细胞表面特性相关，因此在植入式医疗器械上形成生物膜的能力也不同。在一组来自一名手术患者的六个临床标本中，获得了稳定的光滑形态和绉状形态的分离株，我们在表型和基因组水平上研究了其中五个分离株之间的差异。与最初认为它们是克隆菌株的转换形式的假设相反，核型分析和基因组测序表明，该患者至少被三种不同的谱系定殖。统计分析将这些群体在该酵母种群中分得很开。有趣的是，单一血培养分离株呈光滑形态，与患者鼻子中形态相似的分离株匹配。在编码黏附素的基因中，分离株之间存在很大差异，其中重复区域的长度和重复次数有显著变化，在光滑分离株的某一基因中最为明显。虽然药敏性没有明显差异，但各菌株之间的系统发育距离较远，这突出了在常规实践中对多个菌落进行检测的必要性。血流分离株中缺乏生物膜形成表明细胞壁中缺乏相应的黏附素，反过来表明缺乏黏附是传播的一个积极促成因素。
