A comparison of the costs, reliability and time of result periods of widely used methods, new molecular methods and MALDI Tof-Ms in the routine diagnosis of Candida strains [Candida Tür Tayininde Rutinde Yaygin Olarak Kullanilan Yöntemlerle Yeni Kullanilmaya Başlayan MALDI TOf-Ms ve Moleküler Yöntemlerin sonuç Verme süreleri, Maliyetleri ve Güvenilirliklerinin Karşilaştirilmasi]

Abstract

In recent years, the fast and accurate identification of the Candida species is of great importance as the response to antifungal treatment differs among species. Following the treatment of several immunosuppressive diseases, fungal infections can emerge. The aim of this study was to compare the accuracy, costs and time of result periods of the methods used in the identification of the most common human fungal infectious agent, Candida strains. From various clinical samples sent to the Microbiology Laboratory of Karabuk University Training and Research Hospital between July 2016-December 2017, a total of 91 yeast isolates cultivated in blood agar (Becton Dickinson, USA) and/or Sabouraud dextrose agar (SDA-Oxoid, UK), confirmed with colony morphology and microscopic appearance, identified as Candida species with a fully automated identification system (Phoenix™ Yeast ID Panel, Becton Dickinson Diagnostics, USA) were included in the study. All the samples were examined with sequence analysis using ITS1 forward 5'-TCC GTA GGT GAA CCT GCG G-3' and ITS4 reverse 5'-TCC TCC GCT TAT TGA TAT GC-3' primers (Iontek, Turkey) and the matrix-assisted laser desorption-ionisation time of flight mass spectrometry (MALDI TOF-MS) systems. Molecular sequence analysis was accepted as the gold standard method and the results were compared with those of the other methods MALDI TOF-MS and Phoenix" Yeast ID Panel in respect of the accuracy of the identification of Candida strains. According to the results of the DNA sequence analysis of the 91 Candida isolates included in the study, 24 were identified as Candida albicans, 20 Candida tropicalis, 16 Candida parapsilosis, 13 Candida glabrata, seven Candida kefyr, six Candida krusei, two of each Candida dubliniensis, Candida guilliermondi and one Candida lusitaniae. Compared to the results of the DNA sequence analysis, the accurate identification of the fully automated Phoenix" system and the MALDI TOF-MS system was found as 92.3% and 97.8%, respectively. In addition to accuracy, costs and time of result periods of the three methods were also compared. Disregarding the cost of the device in the 3 methods, when the comparison was made of the cost per test and the time to results after pure production in sDA agar, the MALDI Tof-Ms system was determined to have the lowest costs and provided results in the shortest time. As some of the Candida strains have antifungal resistance, identification of the strains must be a priority in respect of starting early treatment. The MALDI TOF-MS system has high performance in accurate identification, low costs and the system provides the results within minutes, thereby allowing immediate decision to be made for the antifungal treatment to be started. Thus, the morbidity, mortality and cost rates will be reduced. In conclusion, as the MALDI TOF-MS is a rapid, reliable and low cost per test system, it can be considered suitable for routine use in laboratories. © 2019 Ankara Microbiology Society. All rights reserved.