ATR-FTIR SPECTROSCOPIC INVESTIGATION OF IMIPENEM-SUSCEPTIBLE AND IMIPENEM-RESISTANT PSEUDOMONAS-AERUGINOSA ISOGENIC STRAINS

The primary mechanism of imipenem resistance in Pseudomonas aeruginosa has been ascribed to an outer membrane impermeability owing to a loss of expression of protein D2. Attenuated total reflection-Fourier tran sform infrared spectroscopy in conjunction with statistical methods ha s been used as a new approach to rapidly discriminate four isogenic st rains of P. aeruginosa-susceptible, less susceptible, and highly resis tant to imipenem-and to follow the structural modifications related to this low permeability. Decomposition of the broad protein and carbohy drate contours into underlying Gaussians and comparison of the suscept ible and highly resistant strain provided quantitative and ultrastruct ural information on these strains. This methodology allows for discrim ination not of the mutation itself but of its consequences observed in the protein and carbohydrate absorption regions. Its association with other existing biochemical methods may be envisaged since it may allo w for rapid orientation of investigations in the field of bacterial re sistance diagnosis. (C) 1997 Academic Press.