Martínez-Lamas Lucía, Pérez del Molino María Luisa, Pardo Fernanda, Varela Eduardo, Regueiro Benito José
Servicio de Microbiología y Parasitología, Complexo Hospitalario Universitario de Santiago de Compostela, Santiago de Compostela, España.
Enferm Infecc Microbiol Clin. 2011 Oct;29(8):568-72. doi: 10.1016/j.eimc.2011.03.014. Epub 2011 Jul 22.
Candida infection has become a major health problem worldwide. The epidemiology of Candidaemia has substantially changed by the emergence of the species Candida non-albicans. This variation is particularly important in the choice of prophylaxis and empirical treatment. The methods based on biochemical and molecular biology have limitations for the correct identification of Candida species. The aim of this study is to demonstrate the ability of the MALDI-TOF mass spectrometry for the identification of these species and compare it with the technology used today.
We included all isolates collected over 2 years (n=73) of Candida non-albicans from non-invasive samples. The identification was carried out by Vitek-2 systems YST and API CAUX. The MALDI-TOF identifications were made with Confidence Axima system (Shimadzu Corporation) using the Shimadzu Launchpad software and database SARAMIS (AnagnosTec GmbH). Discrepancies were resolved by SeptiFast LightCycler multiplex PCR, specific PCR C. glabrata and enzymatic digestion with BanI SADH fragment in isolates of C. parapsilosis.
Of the 73 isolates of Candida non-albicans, the biochemical methods conclusively identified 67 to species level and 6 at the genus level. The MALDI-TOF system obtained identifications at the species level in all cases. The correlation in the species of all isolates studied was 85.07%, reaching 94.52% when the correlation was made between the identification obtained by biochemical methods and the methods for the analysis of the discrepancies. In isolates of C. parapsilosis, MALDI-TOF system obtained an identification of C. orthopsilosis. In 3 of them it was confirmed by digestion with BanI SADH fragment.
This study has demonstrated the use of mass spectrometry (MALDI-TOF system) to provide the microbiology laboratory with greater efficiency and reliability to identify isolates of Candida non-albicans to species level. It also shows its potential usefulness in identifying related species, such as C. parapsilosis, metapsilosis and orthopsilosis.
念珠菌感染已成为全球主要的健康问题。非白色念珠菌的出现使念珠菌血症的流行病学发生了重大变化。这种变化在预防和经验性治疗的选择中尤为重要。基于生化和分子生物学的方法在正确鉴定念珠菌种类方面存在局限性。本研究的目的是证明基质辅助激光解吸电离飞行时间质谱（MALDI-TOF）用于鉴定这些种类的能力，并将其与当今使用的技术进行比较。
我们纳入了2年期间从非侵入性样本中收集的所有非白色念珠菌分离株（n = 73）。通过Vitek-2系统YST和API CAUX进行鉴定。使用岛津Launchpad软件和SARAMIS数据库（AnagnosTec GmbH），通过Confidence Axima系统（岛津公司）进行MALDI-TOF鉴定。通过SeptiFast LightCycler多重PCR、光滑念珠菌特异性PCR以及近平滑念珠菌分离株中BanI SADH片段的酶切消化来解决差异。
在73株非白色念珠菌分离株中，生化方法最终鉴定出67株到种水平，6株到属水平。MALDI-TOF系统在所有情况下均获得了种水平的鉴定结果。所有研究分离株在种水平的相关性为85.07%，当生化方法获得的鉴定结果与差异分析方法之间进行相关性分析时，相关性达到94.52%。在近平滑念珠菌分离株中，MALDI-TOF系统鉴定出了正平滑念珠菌。其中3株通过BanI SADH片段酶切消化得到了证实。
本研究证明了质谱（MALDI-TOF系统）的应用，可为微生物实验室提供更高的效率和可靠性，以将非白色念珠菌分离株鉴定到种水平。它还显示了其在鉴定相关种类方面的潜在用途，如近平滑念珠菌、间平滑念珠菌和正平滑念珠菌。
