Matrix-assisted laser desorption ionization: time of flight mass spectrometry-identified models for detection of ESBL-producing bacterial strains.
BACKGROUND
The increase in the amount of extended spectrum beta-lactamases (ESBL)-producing gram-negative bacteria is seriously threatening human health in recent years. Therefore, it is necessary to develop a rapid and reliable method for identification of ESBLs. The purpose of this study was to establish a novel method to discriminate between ESBL-producing and non- ESBL-producing bacteria by using the matrix-assisted laser desorption/ionization time of flight mass spectrometry (MALDI-TOF-MS) technique.


METHODS
We detected hydrolyzed production of cefotaxime after incubation with 69 gram-negative bacteria by using MALDI-TOF-MS. Then we established genetic algorithm (GA), supervised neural networks (SNN), and quick classifier (QC) models using several peaks to identify ESBL-producing strains. To confirm the clinical applicability of the models established, a blinded validation test was performed in 34 clinical isolated strains.


RESULTS
Using ClinPro Tools software, we identified 4 peaks (456 Da, 396 Da, 370 Da, and 371 Da) in mass spectra of cefotaxime solution that have high enough specificity to discriminate ESBL-producing from non- ESBL-producing strains. Recognition capability of models established were 97.5% (GA), 92.5% (SNN), and 92.5% (QC), and cross validation rates were 90.15% (GA), 97.62 (SNN), and 97.62% (QC). The accuracy rates of the blinded validation test were 82.4% (GA), 88.2% (SNN), and 82.4% (QC).


CONCLUSIONS
Our results demonstrate that identification of ESBLs strains by MALDI-TOF-MS has potential clinical value and could be widely used in the future as a routine test in clinical microbiology laboratories.
Graduate Student Team, Chinese PLA Postgraduate Medical School, Beijing, China (mainland).
Bo
B
Li
Center for Clinical Laboratory, 302 Hospital of PLA, Beijing, China (mainland).
Tongsheng
T
Guo
Center for Clinical Laboratory, 302 Hospital of PLA, Beijing, China (mainland).
Fen
F
Qu
Center for Clinical Laboratory, 302 Hospital of PLA, Beijing, China (mainland).
Boan
B
Li
Center for Clinical Laboratory, 302 Hospital of PLA, Beijing, China (mainland).
Haibin
H
Wang
Center for Clinical Laboratory, 302 Hospital of PLA, Beijing, China (mainland).
Zhiqiang
Z
Sun
Center for Clinical Laboratory, 302 Hospital of PLA, Beijing, China (mainland).
Xiaohan
X
Li
Center for Clinical Laboratory, 302 Hospital of PLA, Beijing, China (mainland).
Zhiqiang
Z
Gao
Center for Clinical Laboratory, 302 Hospital of PLA, Beijing, China (mainland).
Chunmei
C
Bao
Center for Clinical Laboratory, 302 Hospital of PLA, Beijing, China (mainland).
Chenglong
C
Zhang
Center for Clinical Laboratory, 302 Hospital of PLA, Beijing, China (mainland).
Xiaoxi
X
Li
Center for Clinical Laboratory, 302 Hospital of PLA, Beijing, China (mainland).
Yuanli
Y
Mao
D000465:Algorithms; D001419:Bacteria / Q000201:enzymology* / Q000302:isolation & purification; D002439:Cefotaxime / Q000737:chemistry; D015180:Electrophoresis, Gel, Two-Dimensional; D006801:Humans; D008954:Models, Biological; D008970:Molecular Weight; D012372:ROC Curve; D015203:Reproducibility of Results; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization / Q000379:methods*; D001618:beta-Lactamases / Q000096:biosynthesis*
D001618:beta-Lactamases; D002439:Cefotaxime