title: Label-free identification of antibiotic resistant isolates of living Escherichia coli: Pilot study.
abstract: We introduce a label-free spectroscopic method to classify subtypes of quinolone-nonsusceptible Escherichia coli (E. coli) isolates obtained from human blood cultures. Raman spectroscopy with a 30-nm gold-deposited, surface-enhanced Raman scattering (SERS) substrate was used to evaluate three multilocus sequencing typing (MLST)-predefined groups including E. coli ATCC25922, E. coli ST131:O75, and E. coli ST1193:O25b. Although there was a coffee-ring effect, the ring zone was selected at the ideal position to screen E. coli isolates. Strong Raman peaks were present at 1001-1004 cm-1(CC aromatic ring breathing stretching vibrational mode of phenylalanine), 1447-1448 cm-1(CH2scissoring deformation vibrational mode), and 1667 cm-1(amide I α-helix). Although the three MLST-predefined E. coli isolates had similar Raman spectral patterns, a support vector machine (SVM) learning algorithm-assisted principal component analysis (PCA) analysis had superior performance in detecting the presence of quinolone-nonsusceptible E. coli isolates as well as classifying similar microbes, such as quinolone-nonsusceptible E. coli ST131:O75 and E. coli ST1193:O25b isolates. Therefore, this label-free and nondestructive technique is likely to be useful for clinically diagnosing quinolone-nonsusceptible E. coli isolates with the MLST method.
authors.affiliation: Department of Laboratory Medicine, School of Medicine, Kyung Hee University, Seoul, 02447, Korea.
authors.forename: Youjin
authors.initials: Y
authors.lastname: Cheong
authors.affiliation: Department of Laboratory Medicine, School of Medicine, Kyung Hee University, Seoul, 02447, Korea.
authors.forename: Young
authors.initials: Y
authors.lastname: Jin Kim
authors.affiliation: Department of Laboratory Medicine, School of Medicine, Kyung Hee University, Seoul, 02447, Korea.
authors.forename: Heeyoon
authors.initials: H
authors.lastname: Kang
authors.affiliation: Department of Biomedical Engineering, College of Medicine, Kyung Hee University, Seoul, 02447, Korea.
authors.forename: Samjin
authors.initials: S
authors.lastname: Choi
authors.affiliation: Department of Laboratory Medicine, School of Medicine, Kyung Hee University, Seoul, 02447, Korea.
authors.forename: Hee
authors.initials: H
authors.lastname: Joo Lee
mesh_terms: D000465:Algorithms; D024901:Drug Resistance, Multiple, Bacterial; D004926:Escherichia coli / Q000737:chemistry / Q000145:classification* / Q000187:drug effects / Q000302:isolation & purification*; D004927:Escherichia coli Infections / Q000097:blood / Q000175:diagnosis / Q000382:microbiology; D006801:Humans; D058885:Multilocus Sequence Typing; D010865:Pilot Projects; D025341:Principal Component Analysis; D015363:Quinolones / Q000494:pharmacology; D013059:Spectrum Analysis, Raman / Q000379:methods*; D060388:Support Vector Machine
chemical_list: D015363:Quinolones
keywords: Escherichia coli; Raman spectroscopy; multilocus sequence typing; quinolone-nonsusceptible