Examination of Conditions for External Quality Control in Identification of Microorganisms using Matrix-Assisted Laser Desorption/Ionization Time-of-Flight Mass Spectrometry

Abstract

Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) was approved for medical use in 2011 and is currently used as a rapid, accurate and lowcost technique for bacterial identification. External quality control for medical analysis is monitored using tests of the Japanese Association of Medical Technologists and Prefectural Association of Clinical Laboratory Technologists and through user surveys of reagent and equipment manufacturers. However, external quality control of bacterial typing using MS is not performed. Therefore, we examined procedures for evaluating quality control of bacterial typing using an identification reliability index at 38 facilities.

External quality control survey on identification of microorganisms using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry

“…An external accuracy survey was conducted by the Japanese Association of Medical Technologists (JAMT) and prefectural associations of clinical laboratory technologists, and through user surveys of reagent equipment manufacturers. However, since external accuracy control of bacterial typing using MS is performed on a small scale, we also developed procedures for this process using MALDI-TOF MS (Sogawa et al, 2022) . In this report, we describe the results of these procedures for evaluation of external accuracy control of bacterial typing with MS at 228 sites, using the identification consistency rate (Score Value) .…”

“…The Japan Hospital Association conducted a survey of internal accuracy control in 2017 and found that more than 90% of sites performed internal accuracy control of biochemical and hematology tests, but that only 54.8% controlled the internal accuracy of microbiology tests. In addition, more than 98.0% of sites performed external accuracy control of biochemical and hematology tests, whereas only 90.4% performed external accuracy control of microbiology tests (Sogawa et al, 2022) .…”

“…External accuracy control of bacterial typing using MS remains to be standardized by assessment method. Therefore, we developed procedures for this process based on an identification consistency rate (Score Value) (Sogawa et al, 2022) . The following strains were chosen as standards: Gram-negative bacillus S. maltophilia (Yamashita, 2017) , which has thin peptidoglycan layers that suggests that its ribosome-derived proteins are likely to be ionized; and Gram-positive cocci E. faecium (Yamashita, 2017) , which has thick cell walls and a firm structure, making it unlikely that its ribosome-derived proteins will be ionized.…”