Attenuated total reflection: Fourier transform infrared spectroscopy for detection of heterogeneous vancomycin—intermediate Staphylococcus aureus

Sujintana Wongthong, Patcharaporn Tippayawat, Molin Wongwattanakul, Pirom Poung-ngern, Lumyai Wonglakorn, Aroonwadee Chanawong, Philip Heraud, Aroonlug Lulitanond

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Staphylococcus aureus strains resistant to the last line antibiotic, vancomycin, have been of clinical concern. These include heterogeneous vancomycin-intermediate S. aureus (hVISA) and VISA. The hVISA phenotype cannot be detected by routine laboratory methods. Characterization of hVISA/VISA by new technologies is necessary to differentiate them rapidly from the vancomycin-susceptible isolates (VSSA). In this study, we developed a model for discrimination of hVISA from VSSA by using attenuated total reflection-Fourier transform infrared (ATR-FTIR) spectroscopy combined with multivariate data analysis, displaying a phenotypic signature of the bacteria. ATR-FTIR spectra were acquired from a total of 59 clinical methicillin-resistant S. aureus (MRSA) isolates comprising 28 hVISA and 31 VSSA strains. Principal component analysis (PCA) and partial least square discriminant analysis (PLS-DA) were used to analyze 351 spectra of 39 isolates and develop a discrimination model for identifying hVISA and VSSA. The classification model, which was used for blind testing of 90 spectra from each of 10 hVISA, and 10 VSSA isolates, provided 100% sensitivity and specificity. The modeling revealed that the major discrimination between hVISA and VSSA phenotypes involved bands related to cell wall content (1087 and 1057 cm−1). This study showed that ATR-FTIR technique may be an alternative method for rapid detection of low-level vancomycin-resistant S. aureus.

Original languageEnglish
Article number22
Number of pages12
JournalWorld Journal of Microbiology & Biotechnology
Issue number2
Publication statusPublished - 18 Jan 2020


  • Fourier transform infrared spectroscopy
  • Heteroresistance
  • Methicillin-resistant staphylococcus aureus
  • Partial least square discriminant analysis
  • Vancomycin resistance

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