In Young Yoo1, Hyang Jin Shim2, Sun Ae Yun2, On Kyun Kang3, Yoo Na Chung3, Tae Yeul Kim3, Hyeyoung Lee4, Jayoung Kim4, Yeon-Joon Park1, Hee Jae Huh5, Nam Yong Lee6. 1. Department of Laboratory Medicine, Seoul St. Mary's Hospital, College of Medicine, The Catholic University of Korea, Seoul, Republic of Korea. 2. Center for Clinical Medicine, Samsung Biomedical Research Institute, Samsung Medical Center, Seoul, Republic of Korea. 3. Department of Laboratory Medicine and Genetics, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Republic of Korea. 4. Department of Laboratory Medicine, International St. Mary's Hospital, College of Medicine, The Catholic Kwandong University, Incheon, Republic of Korea. 5. Department of Laboratory Medicine and Genetics, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Republic of Korea. Electronic address: pmhhj77@gmail.com. 6. Department of Laboratory Medicine and Genetics, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Republic of Korea. Electronic address: micro.lee@samsung.com.
Abstract
OBJECTIVES: We evaluated the performance of the MicroIDSys Elite system, a newly developed matrix-assisted laser desorption ionization time-of-flight (MALDI-TOF) mass spectrometry system for identification of mycobacteria directly from positive MGIT liquid cultures. METHODS: Analytical specificity was evaluated with 63 reference strains grown in mycobacteria growth indicator tube media. Prospective performance evaluation was conducted with primary liquid cultures of sputum samples for identification of mycobacteria, and results were compared to multigenerational sequencing as the reference method. Liquid media subcultures were also analyzed. RESULTS: The accuracy for the 63 reference strains was 98.4% (62/63). A total of 167 paired mycobacterial primary cultures and subcultures in liquid media, comprised of seven Mycobacterium tuberculosis isolates, 109 slowly growing nontuberculous mycobacterial isolates, and 51 rapidly growing nontuberculous mycobacterial isolates, was identified by the MicroIDSys Elite system. Using primary liquid cultures, the MicroIDSys Elite system correctly identified 143 (85.6%) isolates; 21 (12.6%) resulted in "no identification"; and three (1.8%) isolates were misidentified. Using liquid media subcultures with this system, 159 (95.2%) isolates were correctly identified; seven (4.2%) resulted in "no identification"; and one (0.6%) isolate was misidentified. CONCLUSION: The MicroIDSys Elite system is a useful routine diagnostic tool for identification of mycobacterial species from liquid culture.
OBJECTIVES: We evaluated the performance of the MicroIDSys Elite system, a newly developed matrix-assisted laser desorption ionization time-of-flight (MALDI-TOF) mass spectrometry system for identification of mycobacteria directly from positive MGIT liquid cultures. METHODS: Analytical specificity was evaluated with 63 reference strains grown in mycobacteria growth indicator tube media. Prospective performance evaluation was conducted with primary liquid cultures of sputum samples for identification of mycobacteria, and results were compared to multigenerational sequencing as the reference method. Liquid media subcultures were also analyzed. RESULTS: The accuracy for the 63 reference strains was 98.4% (62/63). A total of 167 paired mycobacterial primary cultures and subcultures in liquid media, comprised of seven Mycobacterium tuberculosis isolates, 109 slowly growing nontuberculous mycobacterial isolates, and 51 rapidly growing nontuberculous mycobacterial isolates, was identified by the MicroIDSys Elite system. Using primary liquid cultures, the MicroIDSys Elite system correctly identified 143 (85.6%) isolates; 21 (12.6%) resulted in "no identification"; and three (1.8%) isolates were misidentified. Using liquid media subcultures with this system, 159 (95.2%) isolates were correctly identified; seven (4.2%) resulted in "no identification"; and one (0.6%) isolate was misidentified. CONCLUSION: The MicroIDSys Elite system is a useful routine diagnostic tool for identification of mycobacterial species from liquid culture.