Division of Infectious Diseases, Federal University of São Paulo, São Paulo, Brazil.
Med Mycol. 2010 Aug;48(5):757-62. doi: 10.3109/13693780903501689.
Multilocus sequence typing (MLST) is a useful tool to explore the phylogenetics and epidemiology of Candida albicans isolates recovered from cases of invasive candidiasis. The goal of this study was to determine whether the same or different strains were responsible for persistent or recurrent fungemia through the use of MLST and ABC typing on sequential C. albicans isolates from the same patient. We applied both typing methods to 21 C. albicans strains recovered from 8 patients with persistent or recurrent candidemia. The isolates were collected during a multicenter surveillance study in four public tertiary care hospitals in Brazil. Persistent candidemia was defined as two or more blood cultures positive for C. albicans on 2 or more separate days. Recurrent candidemia was defined as an episode of candidemia occurring at least 1 month after the apparent complete resolution of an infectious episode caused by Candida species. We observed that, except for one patient, all strains from the first and second samples of the same patient showed the same MLST diploid sequence type (DST), ABC type and susceptibility profile to antifungals. Three distinct strains, well discriminated by MLST, were found in the seven samples collected sequentially over 10 days from one patient. The strains from the first four samples were indistinguishable, the fifth and sixth were also indistinguishable but different from the first four and seventh samples. Significantly, the seventh strain was the only C. albicans clade 2 isolate found in our total collection involving 61 patients, although clade 2 is commonly found worldwide. To the best of our knowledge, this is the first study describing the recovery of three distinct C. albicans strains in the same patient with a persistent blood stream infection within a short period of time.
多位点序列分型（MLST）是一种有用的工具，可用于探索从侵袭性念珠菌病病例中分离出的白色念珠菌的系统发生和流行病学。本研究的目的是通过对来自同一患者的连续白色念珠菌分离物进行 MLST 和 ABC 分型，确定是否是相同或不同的菌株导致持续性或复发性菌血症。我们将这两种分型方法应用于从巴西 4 家公立医院的 8 例持续性或复发性菌血症患者中分离出的 21 株白色念珠菌。分离株是在巴西四个公共三级保健医院的一项多中心监测研究中收集的。持续性菌血症定义为两次或更多次血培养阳性，且至少 2 天内至少 2 次阳性。复发性菌血症定义为念珠菌属引起的感染发作明显完全缓解后至少 1 个月发生的念珠菌血症发作。我们观察到，除了 1 例患者外，同一患者的第一和第二份样本的所有菌株均表现出相同的 MLST 二倍体序列型（DST）、ABC 型和抗真菌敏感性谱。从一名患者连续 10 天采集的 7 份样本中发现了 3 株不同的菌株，这些菌株通过 MLST 得到很好的区分。前 4 份样本的菌株无法区分，第 5 和第 6 份样本也无法区分，但与前 4 份和第 7 份样本不同。值得注意的是，第 7 株菌株是我们总共涉及 61 例患者的采集样本中唯一发现的白色念珠菌 2 型菌株，尽管白色念珠菌 2 型在全球范围内都很常见。据我们所知，这是第一项在短时间内描述同一患者持续性血流感染中分离出 3 株不同白色念珠菌菌株的研究。
