Surface-enhanced infrared absorption spectroscopy for microorganisms discrimination on silver nanoparticle substrates

•The performance of surface-enhanced infrared absorption spectroscopy (SEIRAS) for the discrimination of microorganisms is evaluated by emphasizing the source of the observed spectral pattern by comparing to surface-enhanced Raman spectroscopy (SERS).•The same sample preparation for both SEIRAS and SERS measurements is employed, where microbial sample and citrate-reduced colloidal silver nanoparticles (AgNPs) are simply mixed.•SEIRAS provides very rich molecular information about species adsorbed onto AgNPs similar to the case of SERS although its enhancement factor several orders of magnitude lower than that of SERS.•The discrimination power of SEIRAS using the bacterial strains is much superior compared to the case of FTIR demonstrated by PCA analysis.