Label-free identification of antibiotic resistant isolates of living Escherichia coli: Pilot study

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• 作者：Youjin Cheong ; Young Jin Kim ; Heeyoon Kang ; Samjin Choi and Hee Joo Lee
• 刊名：Microscopy Research and Technique
• 出版年：2017
• 出版时间：February 2017
• 年：2017
• 卷：80
• 期：2
• 页码：177-182
• 全文大小：499K
• ISSN：1097-0029

文摘

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 (CC aromatic ring breathing stretching vibrational mode of phenylalanine), 1447–1448 cm⁻¹ (CH₂ scissoring 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.