FT-IR spectroscopy study of perturbations induced by antibiotic on bacteria (Escherichia coli).

Fourier transform infrared spectroscopy (FT-IR) is an analysis method which over the spectral absorption, gives information about the molecular structures of systems. Recently, this method is widely used to the investigation of complex systems like cells and bacteria. Characteristic of FT-IR spectrum of bacteria depend closely to physiological and culture parameters. In this study, the infrared bands of intact bacteria are first tentatively attributed to the contribution of the cellular components. Secondly are compared the FT-IR spectra of Escherichia coli bacteria before and after treatment at sub-inhibitrice concentrations (< or = MIC) at penicillin A, penicillin G and nalidixic acid. The observed spectral perturbations are closely depending on the antibiotic treatment and are observed even if bacterial cell mass is far away from cell death. On the other hand, this spectral changes are related to the known mode of action of the used antibiotic.