In recent years, fungi or molds have emerged as the underlying pathogens of life-threatening infections in immunocompromised patients. Timely management of these infections requires rapid and accurate diagnosis of fungi in the clinical setting.
Unfortunately, traditional methods are time consuming given the long incubation period required to culture and test the mold. Advanced molecular techniques, on the other hand, are more sensitive and efficient. One technique that can detect filamentous fungal isolates with high sensitivity and reproducibility is “matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS).” Samples can be distinguished based on changes in mass and charge. However, it is not widely used due to limited database availability and lack of standardized procedures.
Recently, a team of researchers from Chung-Ang University in South Korea, led by Professor Mi-Kyung Lee, evaluated three different MALDI-TOF MS approaches used in domestic clinical settings for the identification of fungi.
their Research published in Journal of Clinical Microbiology On October 26, 2022, they compared the performance and diagnostic accuracy of Bruker Biotyper, ASTA MicroIDSys and Vitek MS. They also evaluated the sensitivity of his three pretreatment methods: ‘direct’, ‘on plate’ and ‘in tube’ using 84 filamentous fungal isolates.
Explaining the rationale behind their research, Professor Lee said: “Choosing an appropriate sample preparation method can improve the efficiency and accuracy of mold identification. Furthermore, the development of systematic processes at the diagnostic level will ultimately lead to effective patient We can contribute to the treatment.”
The study found that ASTA MicroIDSys and Vitek MS showed accuracies of 70.24% and 55.95%, respectively, while Bruker Biotyper correctly identified 71.43% of isolates down to the species or genus level. Moreover, the direct method of sample preparation was superior to his two other methods due to its simplicity and ease of application. Notably, discrimination sensitivity did not differ significantly between different sample preparation methods.
False positive rates are an important consideration in clinical laboratories as they can lead to inappropriate therapeutic interventions for patients. In this study, only one isolate was misidentified using the on-plate method of Vitek-MS.In addition, species-level identification Aspergillus (very common and clinically significant microbes) is highest for Vitek-MS, demonstrating the applicability of this technique in the clinical setting.
The number of incorrectly identified species was 17, 15 and 23 by Bruker Biotyper, ASTA MicroIDSys and Vitek MS, respectively. The team suggested the need for additional evaluation if the misidentification occurred due to the absence of a particular species in the library rather than an error. Additionally, the team determined that differences in sensitivity could be attributed to differences in system databases.
In summary, MALDI-TOF MS is a valuable technique for the timely and accurate identification of clinically relevant microbes. Process standardization and guidelines applicable to a wide range of species can help reduce process biases caused by these techniques. In addition, limitations related to acquisition parameters, matrix quality, and hardware require further evaluation.
When asked about the application of his research, Professor Lee said: “Our study is the first to compare the sensitivity and accuracy of three MALDI-TOF MS instruments and the effectiveness of three pretreatment methods for identifying filamentous fungi. Simple using MALDI-TOF MS. Accurate results obtained through a streamlined fungal identification process in , have the potential to improve user laboratory efficiency and patient care efficiency.”
Author: Choi Yoo Junga, Kim DaewonbChoi KewonaLee Hyuk MincKim Jae SukdJohn Yell AnnbMi Kyung Leea
aDepartment of Laboratory Medicine Chuo University School of MedicineSeoul, South Korea
bDepartment of Laboratory Medicine, Gil Medical Center, Gachon University, Incheon, Republic of Korea
cDepartment of Laboratory Medicine, Yonsei University School of Medicine and Research Institute for Bacterial Resistance, Seoul, Republic of Korea
dDepartment of Laboratory Medicine, Kangdong Sacred Heart Hospital, Hallym University School of Medicine, Seoul, Republic of Korea
About Chuo University
Chung-Ang University is a private comprehensive research university in Seoul, South Korea. It opened as a kindergarten in 1916 and received university status in 1953. Fully accredited by the Korean Ministry of Education. Chuo University conducts research activities under the slogan of “justice and truth.” The new vision to conclude 100 years is “The Global Creative Leader”. Chuo University offers undergraduate, graduate, and doctoral programs, including law schools, management programs, and medical schools. It has 16 faculties and graduate schools each. The culture and arts programs at Chung-Ang University are considered the best in South Korea.
About Chuo University Professor Mikyung Lee
Dr. Mi-Kyung Lee He is a professor at the Department of Laboratory Medicine, Chuan University School of Medicine. She holds a PhD in Laboratory Medicine and is the author of over 230 publications. With over 20 years of her research experience in the fields of clinical microbiology and molecular genetics, her research is currently focused on fungal infections and antifungal drug susceptibility. In 2002, with the support of the Korea Science and Engineering Foundation, she completed a one-year training fellowship at the Department of Fungal Diseases, Centers for Disease Control and Prevention, Atlanta, Georgia, USA.clinical microbiology research (especially Candida species) in Korea.
Journal of Clinical Microbiology
Data and statistical analysis
Performance Evaluation of Bruker Biotyper, ASTA MicroIDSys, and VITEK-MS and Three Extraction Methods for Filamentous Fungal Identification in the Clinical Laboratory
Article publication date
October 26, 2022