Rapid and robust analytical protocol for E. coli STEC bacteria subspecies differentiation using whole cell MALDI mass spectrometry

Talanta. 2018 May 15:182:164-170. doi: 10.1016/j.talanta.2018.01.055. Epub 2018 Feb 20.

Abstract

Whole cell MALDI is regularly used for the identification of bacteria to species level in clinical Microbiology laboratories. However, there remains a need to rapidly characterize and differentiate isolates below the species level to support outbreak management. We describe the implementation of a modified preparative approach for MALDI-MS combined with a custom analytical computational pipeline as a rapid procedure for subtyping Shigatoxigenic E. coli (STEC) and accurately identifying strain-specifying biomarkers. The technique was able to differentiate E. coli O157:H7 from other STEC. Within O157 serotype O157:H7 isolates were readily distinguishable from Sorbitol Fermenting O157 isolates. Overall, nine homogeneous groups of isolates were distinguished, each exhibiting distinct profiles of defining mass spectra features. This offers a robust analytical tool useable in reference/diagnostic public health scenarios.

Keywords: Escherichia coli; MALDI-MS; Mass spectrometry; STEC; Shigatoxigenic E. coli; Spectral processing.

MeSH terms

  • Bacterial Typing Techniques / methods
  • Bacterial Typing Techniques / statistics & numerical data*
  • Escherichia coli O157 / isolation & purification*
  • Principal Component Analysis
  • Serogroup
  • Shiga-Toxigenic Escherichia coli / isolation & purification*
  • Species Specificity
  • Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization / methods*
  • Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization / statistics & numerical data
  • Time Factors